Home > Products > Valid Products > AFD

000
FXUS65 KPSR 212147 CCA
AFDPSR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PHOENIX AZ
247 PM MST THU AUG 21 2014

.SYNOPSIS...
THERE WILL BE AN INCREASED CHANCE OF SHOWERS AND THUNDERSTORMS
ACROSS THE REGION THIS AFTERNOON AND EVENING AS AN UPPER LEVEL LOW
PRESSURE SYSTEM MOVES THROUGH THE AREA. STORM CHANCES WILL DECREASE
FRIDAY AND THROUGH THE WEEKEND AS DRIER AIR OVERSPREADS THE AREA.
BELOW NORMAL TEMPERATURES ARE FORECAST THROUGH SATURDAY...GRADUALLY
RETURNING TO NORMAL EARLY NEXT WEEK.

&&

.DISCUSSION...
THUNDERSTORM ACTIVITY HAS RAPIDLY PICKED UP THIS AFTERNOON ACROSS
OUR SOUTHEAST CALIFORNIA ZONES...THE LOWER COLORADO RIVER VALLEY...
AND AS FAR EAST AS CENTRAL LA PAZ AND YUMA COUNTIES. SOME OF THESE
STORMS HAVE QUICKLY CLUSTERED AND EVOLVED TO SEVERE STATUS WITH
STRONG WINDS IN EXCESS 55KT...OTHER ISOLATED STORMS HAVE BEEN
EFFICIENT RAIN PRODUCERS WITH RADAR RAINFALL ESTIMATES OF 1-2 INCHES
PER HOUR.

CLOUD COVER AND COOLER TEMPERATURES ACROSS SOUTH-CENTRAL ARIZONA
CREATED A MORE STABLE ENVIRONMENT AND THUS TOOK A BITE OUT OF THE
CONVECTIVE POTENTIAL THIS AFTERNOON AND HAS KEPT STORM ACTIVITY TO A
MINIMUM SO FAR. THE HIGH AT PHOENIX PEAKED OUT AT 88 DEGREES AND
THAT WAS AT 10 AM THIS MORNING. HOWEVER...AS THE LOW GRADUALLY
SHIFTS EAST...THE COLD CORE 500MB TEMPS/-10 TO 12C/ WILL EVENTUALLY
MOVE OVER SOUTH-CENTRAL ARIZONA...IMPROVING LAPSE RATES/INSTABILITY.
EXPECT SHOWERS/THUNDERSTORMS TO FORM AND EVENTUALLY SPREAD EAST
ACROSS MARICOPA COUNTY/PHOENIX METROPOLITAN AREA BY EARLY
EVENING...CONTINUING INTO THE HIGHER TERRAIN OF SOUTHERN GILA
COUNTY...NORTHERN AND EASTERN ARIZONA BEFORE MIDNIGHT.

THE LOW WILL MOVE MOVE ACROSS THE STATE TONIGHT...THE TROUGH AXIS
EXPECTED TO BE DRAPED ACROSS THE CENTRAL ARIZONA BY LATE FRIDAY
MORNING. MID LEVEL FLOW BEHIND THE DEPARTING TROUGH TURNS SHARPLY
OUT OF THE WEST LATE TONIGHT INTO FRIDAY...SO MOISTURE GETS SCOURED
OUT AND THE FLOW BECOMES LESS FAVORABLE FOR STORMS FRIDAY AFTERNOON.
WOULD ANTICIPATE THAT THE ATMOSPHERE WILL BE PRETTY WORKED OVER AND
MORE STABLE ACROSS OUR ENTIRE FORECAST AREA FROM THIS EVENINGS
ACTIVITY THAT LITTLE IN THE WAY OF CONVECTIVE STORMS WILL
MATERIALIZE FRIDAY. STILL KEEPING SLIGHT CHANCE POPS GOING ACROSS
SOUTHERN GILA COUNTY FOR FRIDAY AFTERNOON...AND MUCH OF THE SAME IS
EXPECTED FOR SATURDAY AND SUNDAY AS LOW LEVEL MIXING RATIOS CONTINUE
TO FALL TO AROUND 5-6 G/KG THIS WEEKEND. DAYTIME TEMPERATURES WILL
CONTINUE TO BE BELOW NORMAL AS WE END THE WEEK...HOLDING IN THE MID
TO UPPER 90S OVER THE LOWER DESERTS FRIDAY AFTERNOON...BARLEY
BREAKING THE 100 DEGREE MARK SATURDAY AFTERNOON...AND A FEW MORE
DEGREES OF WARMING FOR SUNDAY.

THERE IS A GENERAL AGREEMENT AMONG THE OPERATIONAL MODELS AND
ENSEMBLES THAT MOISTURE WILL RETURN TO THE AREA MONDAY/TUESDAY...
ALTHOUGH AT THIS POINT THERE DOES NOT APPEAR TO BE ANY CLEAR SIGNALS
ON WHICH DAY WILL BE ACTIVE. GOING TO RETAIN A LOW-GRADE MONSOON POP
FORECAST EACH AFTERNOON MONDAY THROUGH THURSDAY ALONG WITH NEAR
NORMAL TEMPERATURES.

&&

.AVIATION...
SOUTH-CENTRAL ARIZONA INCLUDING KPHX...KIWA...AND KSDL...
PERSISTENT CLOUDINESS HAS KEPT TEMPERATURES WELL BELOW NORMAL ACROSS
THE AREA. CONSEQUENTLY...INSTABILITY IS DIMINISHED AND THE THREAT
FOR THUNDERSTORMS HAS DECREASED. HOWEVER...INSTABILITY WILL INCREASE
AGAIN LATE THIS AFTERNOON AND THIS EVENING AS AN AREA OF LOW
PRESSURE MOVES INTO SOUTHWESTERN AZ. ISOLATED TO SCATTERED STORMS
ARE POSSIBLE ACROSS THE PHOENIX AREA...PARTICULARLY IN THE 01Z-05Z
PERIOD. THE STRONGEST STORMS WILL BE CAPABLE OF PRODUCING HEAVY
RAIN...STRONG TO SEVERE WIND GUSTS AND PERHAPS EVEN LARGE HAIL. CIGS
MAY ALSO LOWER TO AROUND 7K FT WITH OCCASIONAL VSBY RESTRICTIONS
BELOW 6SM. CONDITIONS WILL IMPROVE AFTER 06Z WITH A BREAK IN THE
MONSOON ACTIVITY BEGINNING FRIDAY.

SOUTHEAST CALIFORNIA AND SOUTHWEST ARIZONA INCLUDING KIPL AND KBLH...
THUNDERSTORMS WILL CONTINUE TO INCREASE IN COVERAGE THIS AFTERNOON
AT BOTH KIPL AND KBLH. THE STRONGEST STORMS WILL BE CAPABLE OF
PRODUCING HEAVY RAIN...STRONG TO SEVERE WIND GUSTS AND LARGE HAIL.
CIGS MAY ALSO LOWER TO AROUND 6K FT WITH OCCASIONAL VSBY
RESTRICTIONS BELOW 6SM. CONDITIONS WILL IMPROVE AFTER 04Z WITH A
BREAK IN THE MONSOON ACTIVITY BEGINNING FRIDAY.

AVIATION DISCUSSION NOT UPDATED FOR AMENDED TAFS.

&&

.FIRE WEATHER...
SATURDAY THROUGH WEDNESDAY...
HUMIDITIES TREND DOWNWARD SOME MORE OVER THE WEEKEND BEFORE
REBOUNDING SOME NEXT WEEK. AIR WILL BE DRIEST OVER SOUTHEAST
CALIFORNIA AND HAINES INDEX VALUES CLIMB TO 5 BEFORE IMPROVING BY
TUESDAY. HAINES VALUES WILL BE SIGNIFICANTLY LOWER EAST OF THERE DUE
TO BETTER MOISTURE. OVERNIGHT RECOVERY WILL REMAIN GOOD...LESS SO
OVER SOUTHEAST CALIFORNIA. STORM CHANCES WILL BE SLIGHT AND LIMITED
TO THE HIGHER TERRAIN OF SOUTH-CENTRAL ARIZONA THROUGH
TUESDAY...EXPANDING WESTWARD WEDNESDAY.

&&

.PSR WATCHES/WARNINGS/ADVISORIES...

AZ...NONE.

CA...NONE.

&&

$$

VISIT US ON FACEBOOK...TWITTER...AND AT WEATHER.GOV/PHOENIX

DISCUSSION...MEYERS/LEINS
AVIATION...HIRSCH
FIRE WEATHER...AJ







000
FXUS65 KPSR 212147 CCA
AFDPSR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PHOENIX AZ
247 PM MST THU AUG 21 2014

.SYNOPSIS...
THERE WILL BE AN INCREASED CHANCE OF SHOWERS AND THUNDERSTORMS
ACROSS THE REGION THIS AFTERNOON AND EVENING AS AN UPPER LEVEL LOW
PRESSURE SYSTEM MOVES THROUGH THE AREA. STORM CHANCES WILL DECREASE
FRIDAY AND THROUGH THE WEEKEND AS DRIER AIR OVERSPREADS THE AREA.
BELOW NORMAL TEMPERATURES ARE FORECAST THROUGH SATURDAY...GRADUALLY
RETURNING TO NORMAL EARLY NEXT WEEK.

&&

.DISCUSSION...
THUNDERSTORM ACTIVITY HAS RAPIDLY PICKED UP THIS AFTERNOON ACROSS
OUR SOUTHEAST CALIFORNIA ZONES...THE LOWER COLORADO RIVER VALLEY...
AND AS FAR EAST AS CENTRAL LA PAZ AND YUMA COUNTIES. SOME OF THESE
STORMS HAVE QUICKLY CLUSTERED AND EVOLVED TO SEVERE STATUS WITH
STRONG WINDS IN EXCESS 55KT...OTHER ISOLATED STORMS HAVE BEEN
EFFICIENT RAIN PRODUCERS WITH RADAR RAINFALL ESTIMATES OF 1-2 INCHES
PER HOUR.

CLOUD COVER AND COOLER TEMPERATURES ACROSS SOUTH-CENTRAL ARIZONA
CREATED A MORE STABLE ENVIRONMENT AND THUS TOOK A BITE OUT OF THE
CONVECTIVE POTENTIAL THIS AFTERNOON AND HAS KEPT STORM ACTIVITY TO A
MINIMUM SO FAR. THE HIGH AT PHOENIX PEAKED OUT AT 88 DEGREES AND
THAT WAS AT 10 AM THIS MORNING. HOWEVER...AS THE LOW GRADUALLY
SHIFTS EAST...THE COLD CORE 500MB TEMPS/-10 TO 12C/ WILL EVENTUALLY
MOVE OVER SOUTH-CENTRAL ARIZONA...IMPROVING LAPSE RATES/INSTABILITY.
EXPECT SHOWERS/THUNDERSTORMS TO FORM AND EVENTUALLY SPREAD EAST
ACROSS MARICOPA COUNTY/PHOENIX METROPOLITAN AREA BY EARLY
EVENING...CONTINUING INTO THE HIGHER TERRAIN OF SOUTHERN GILA
COUNTY...NORTHERN AND EASTERN ARIZONA BEFORE MIDNIGHT.

THE LOW WILL MOVE MOVE ACROSS THE STATE TONIGHT...THE TROUGH AXIS
EXPECTED TO BE DRAPED ACROSS THE CENTRAL ARIZONA BY LATE FRIDAY
MORNING. MID LEVEL FLOW BEHIND THE DEPARTING TROUGH TURNS SHARPLY
OUT OF THE WEST LATE TONIGHT INTO FRIDAY...SO MOISTURE GETS SCOURED
OUT AND THE FLOW BECOMES LESS FAVORABLE FOR STORMS FRIDAY AFTERNOON.
WOULD ANTICIPATE THAT THE ATMOSPHERE WILL BE PRETTY WORKED OVER AND
MORE STABLE ACROSS OUR ENTIRE FORECAST AREA FROM THIS EVENINGS
ACTIVITY THAT LITTLE IN THE WAY OF CONVECTIVE STORMS WILL
MATERIALIZE FRIDAY. STILL KEEPING SLIGHT CHANCE POPS GOING ACROSS
SOUTHERN GILA COUNTY FOR FRIDAY AFTERNOON...AND MUCH OF THE SAME IS
EXPECTED FOR SATURDAY AND SUNDAY AS LOW LEVEL MIXING RATIOS CONTINUE
TO FALL TO AROUND 5-6 G/KG THIS WEEKEND. DAYTIME TEMPERATURES WILL
CONTINUE TO BE BELOW NORMAL AS WE END THE WEEK...HOLDING IN THE MID
TO UPPER 90S OVER THE LOWER DESERTS FRIDAY AFTERNOON...BARLEY
BREAKING THE 100 DEGREE MARK SATURDAY AFTERNOON...AND A FEW MORE
DEGREES OF WARMING FOR SUNDAY.

THERE IS A GENERAL AGREEMENT AMONG THE OPERATIONAL MODELS AND
ENSEMBLES THAT MOISTURE WILL RETURN TO THE AREA MONDAY/TUESDAY...
ALTHOUGH AT THIS POINT THERE DOES NOT APPEAR TO BE ANY CLEAR SIGNALS
ON WHICH DAY WILL BE ACTIVE. GOING TO RETAIN A LOW-GRADE MONSOON POP
FORECAST EACH AFTERNOON MONDAY THROUGH THURSDAY ALONG WITH NEAR
NORMAL TEMPERATURES.

&&

.AVIATION...
SOUTH-CENTRAL ARIZONA INCLUDING KPHX...KIWA...AND KSDL...
PERSISTENT CLOUDINESS HAS KEPT TEMPERATURES WELL BELOW NORMAL ACROSS
THE AREA. CONSEQUENTLY...INSTABILITY IS DIMINISHED AND THE THREAT
FOR THUNDERSTORMS HAS DECREASED. HOWEVER...INSTABILITY WILL INCREASE
AGAIN LATE THIS AFTERNOON AND THIS EVENING AS AN AREA OF LOW
PRESSURE MOVES INTO SOUTHWESTERN AZ. ISOLATED TO SCATTERED STORMS
ARE POSSIBLE ACROSS THE PHOENIX AREA...PARTICULARLY IN THE 01Z-05Z
PERIOD. THE STRONGEST STORMS WILL BE CAPABLE OF PRODUCING HEAVY
RAIN...STRONG TO SEVERE WIND GUSTS AND PERHAPS EVEN LARGE HAIL. CIGS
MAY ALSO LOWER TO AROUND 7K FT WITH OCCASIONAL VSBY RESTRICTIONS
BELOW 6SM. CONDITIONS WILL IMPROVE AFTER 06Z WITH A BREAK IN THE
MONSOON ACTIVITY BEGINNING FRIDAY.

SOUTHEAST CALIFORNIA AND SOUTHWEST ARIZONA INCLUDING KIPL AND KBLH...
THUNDERSTORMS WILL CONTINUE TO INCREASE IN COVERAGE THIS AFTERNOON
AT BOTH KIPL AND KBLH. THE STRONGEST STORMS WILL BE CAPABLE OF
PRODUCING HEAVY RAIN...STRONG TO SEVERE WIND GUSTS AND LARGE HAIL.
CIGS MAY ALSO LOWER TO AROUND 6K FT WITH OCCASIONAL VSBY
RESTRICTIONS BELOW 6SM. CONDITIONS WILL IMPROVE AFTER 04Z WITH A
BREAK IN THE MONSOON ACTIVITY BEGINNING FRIDAY.

AVIATION DISCUSSION NOT UPDATED FOR AMENDED TAFS.

&&

.FIRE WEATHER...
SATURDAY THROUGH WEDNESDAY...
HUMIDITIES TREND DOWNWARD SOME MORE OVER THE WEEKEND BEFORE
REBOUNDING SOME NEXT WEEK. AIR WILL BE DRIEST OVER SOUTHEAST
CALIFORNIA AND HAINES INDEX VALUES CLIMB TO 5 BEFORE IMPROVING BY
TUESDAY. HAINES VALUES WILL BE SIGNIFICANTLY LOWER EAST OF THERE DUE
TO BETTER MOISTURE. OVERNIGHT RECOVERY WILL REMAIN GOOD...LESS SO
OVER SOUTHEAST CALIFORNIA. STORM CHANCES WILL BE SLIGHT AND LIMITED
TO THE HIGHER TERRAIN OF SOUTH-CENTRAL ARIZONA THROUGH
TUESDAY...EXPANDING WESTWARD WEDNESDAY.

&&

.PSR WATCHES/WARNINGS/ADVISORIES...

AZ...NONE.

CA...NONE.

&&

$$

VISIT US ON FACEBOOK...TWITTER...AND AT WEATHER.GOV/PHOENIX

DISCUSSION...MEYERS/LEINS
AVIATION...HIRSCH
FIRE WEATHER...AJ








000
FXUS65 KPSR 212145
AFDPSR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PHOENIX AZ
245 PM MST THU AUG 21 2014

.SYNOPSIS...
THERE WILL BE AN INCREASED CHANCE OF SHOWERS AND THUNDERSTORMS
ACROSS THE REGION THIS AFTERNOON AND EVENING AS AN UPPER LEVEL LOW
PRESSURE SYSTEM MOVES THROUGH THE AREA. STORM CHANCES WILL DECREASE
FRIDAY AND THROUGH THE WEEKEND AS DRIER AIR OVERSPREADS THE AREA.
BELOW NORMAL TEMPERATURES ARE FORECAST THROUGH SATURDAY...GRADUALLY
RETURNING TO NORMAL EARLY NEXT WEEK.

&&

.DISCUSSION...
THUNDERSTORM ACTIVITY HAS RAPIDLY PICKED UP THIS AFTERNOON ACROSS
OUR SOUTHEAST CALIFORNIA ZONES...THE LOWER COLORADO RIVER VALLEY...
AND AS FAR EAST AS CENTRAL LA PAZ AND YUMA COUNTIES. SOME OF THESE
STORMS HAVE QUICKLY CLUSTERED AND EVOLVED TO SEVERE STATUS WITH
STRONG WINDS IN EXCESS 55KT...OTHER ISOLATED STORMS HAVE BEEN
EFFICIENT RAIN PRODUCERS WITH RADAR RAINFALL ESTIMATES OF 1-2 INCHES
PER HOUR.

CLOUD COVER AND COOLER TEMPERATURES ACROSS SOUTH-CENTRAL ARIZONA
CREATED A MORE STABLE ENVIRONMENT AND THUS TOOK A BITE OUT OF THE
CONVECTIVE POTENTIAL THIS AFTERNOON AND HAS KEPT STORM ACTIVITY TO A
MINIMUM SO FAR. THE HIGH AT PHOENIX PEAKED OUT AT 88 DEGREES AND
THAT WAS AT 10 AM THIS MORNING. HOWEVER...AS THE LOW GRADUALLY
SHIFTS EAST...THE COLD CORE 500MB TEMPS/-10 TO 12C/ WILL EVENTUALLY
MOVE OVER SOUTH-CENTRAL ARIZONA...IMPROVING LAPSE RATES/INSTABILITY.
EXPECT SHOWERS/THUNDERSTORMS TO FORM AND EVENTUALLY SPREAD EAST
ACROSS MARICOPA COUNTY/PHOENIX METROPOLITAN AREA BY EARLY
EVENING...CONTINUING INTO THE HIGHER TERRAIN OF SOUTHERN GILA
COUNTY...NORTHERN AND EASTERN ARIZONA BEFORE MIDNIGHT.

THE LOW WILL MOVE MOVE ACROSS THE STATE TONIGHT...THE TROUGH AXIS
EXPECTED TO BE DRAPED ACROSS THE CENTRAL ARIZONA BY LATE FRIDAY
MORNING. MID LEVEL FLOW BEHIND THE DEPARTING TROUGH TURNS SHARPLY
OUT OF THE WEST LATE TONIGHT INTO FRIDAY...SO MOISTURE GETS SCOURED
OUT AND THE FLOW BECOMES LESS FAVORABLE FOR STORMS FRIDAY AFTERNOON.
WOULD ANTICIPATE THAT THE ATMOSPHERE WILL BE PRETTY WORKED OVER AND
MORE STABLE ACROSS OUR ENTIRE FORECAST AREA FROM THIS EVENINGS
ACTIVITY THAT LITTLE IN THE WAY OF CONVECTIVE STORMS WILL
MATERIALIZE FRIDAY. STILL KEEPING SLIGHT CHANCE POPS GOING ACROSS
SOUTHERN GILA COUNTY FOR FRIDAY AFTERNOON...AND MUCH OF THE SAME IS
EXPECTED FOR SATURDAY AND SUNDAY AS LOW LEVEL MIXING RATIOS CONTINUE
TO FALL TO AROUND 5-6 G/KG THIS WEEKEND. DAYTIME TEMPERATURES WILL
CONTINUE TO BE BELOW NORMAL AS WE END THE WEEK...HOLDING IN THE MID
TO UPPER 90S OVER THE LOWER DESERTS FRIDAY AFTERNOON...BARLEY
BREAKING THE 100 DEGREE MARK SATURDAY AFTERNOON...AND A FEW MORE
DEGREES OF WARMING FOR SUNDAY.

THERE IS A GENERAL AGREEMENT AMONG THE OPERATIONAL MODELS AND
ENSEMBLES THAT MOISTURE WILL RETURN TO THE AREA MONDAY/TUESDAY...
ALTHOUGH AT THIS POINT THERE DOES NOT APPEAR TO BE ANY CLEAR SIGNALS
ON WHICH DAY WILL BE ACTIVE. GOING TO RETAIN A LOW-GRADE MONSOON POP
FORECAST EACH AFTERNOON MONDAY THROUGH THURSDAY ALONG WITH NEAR
NORMAL TEMPERATURES.

&&

.AVIATION...
SOUTH-CENTRAL AND SOUTHWEST ARIZONA AND FAR SOUTHEAST CALIFORNIA
INCLUDING KPHX...KIWA...KSDL...KBLH...KIPL...

BATCH OF THICK HIGH CLOUDS IN PLACE EAST OF LOWER COLORADO RIVER
VALLEY EARLY THIS MORNING. CLOUDS WILL THICKEN AS THE MORNING GOES
ON AND SCATTERED SHOWERS WILL BEGIN TO DEVELOP BY 15Z WITH EMBEDDED
THUNDERSTORMS DEVELOPING AFTER 18Z. HELD OFF FOR NOW ON PUTTING
SHRA/TSRA IN TEMPO OR PREVAILING GROUPS OF PHOENIX AREA TAFS AS
AREAL COVERAGE OF SHWRS/TSTMS LOOKS TO BE BEST OVER YUMA AND LA PAZ
COUNTIES. THIS IS CERTAINLY SUBJECT TO CHANGE. TSTMS THAT MANAGE TO
FORM WILL HAVE POTENTIAL TO PRODUCE STRONG WINDS AND SMALL HAIL
ALONG WITH DRAMATICALLY LOWERED VISIBILITY AND CEILING. SURFACE
WINDS WILL BECOME ERRATIC LATER IN THE DAY AS STORM ACTIVITY
DEVELOPS BUT OTHERWISE WILL FAVOR WESTERLY DIRECTIONS OVER PHOENIX
AREA AND SOUTHEASTERLY DIRECTIONS OVER LOWER COLORADO RIVER VALLEY
AND IMPERIAL VALLEY.

AVIATION DISCUSSION NOT UPDATED FOR AMENDED TAFS.

&&

.FIRE WEATHER...
SATURDAY THROUGH WEDNESDAY...
HUMIDITIES TREND DOWNWARD SOME MORE OVER THE WEEKEND BEFORE
REBOUNDING SOME NEXT WEEK. AIR WILL BE DRIEST OVER SOUTHEAST
CALIFORNIA AND HAINES INDEX VALUES CLIMB TO 5 BEFORE IMPROVING BY
TUESDAY. HAINES VALUES WILL BE SIGNIFICANTLY LOWER EAST OF THERE DUE
TO BETTER MOISTURE. OVERNIGHT RECOVERY WILL REMAIN GOOD...LESS SO
OVER SOUTHEAST CALIFORNIA. STORM CHANCES WILL BE SLIGHT AND LIMITED
TO THE HIGHER TERRAIN OF SOUTH-CENTRAL ARIZONA THROUGH
TUESDAY...EXPANDING WESTWARD WEDNESDAY.

&&

.PSR WATCHES/WARNINGS/ADVISORIES...

AZ...NONE.

CA...NONE.

&&

$$

VISIT US ON FACEBOOK...TWITTER...AND AT WEATHER.GOV/PHOENIX

DISCUSSION...MEYERS/LEINS
AVIATION...AJ
FIRE WEATHER...AJ







000
FXUS65 KPSR 212145
AFDPSR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PHOENIX AZ
245 PM MST THU AUG 21 2014

.SYNOPSIS...
THERE WILL BE AN INCREASED CHANCE OF SHOWERS AND THUNDERSTORMS
ACROSS THE REGION THIS AFTERNOON AND EVENING AS AN UPPER LEVEL LOW
PRESSURE SYSTEM MOVES THROUGH THE AREA. STORM CHANCES WILL DECREASE
FRIDAY AND THROUGH THE WEEKEND AS DRIER AIR OVERSPREADS THE AREA.
BELOW NORMAL TEMPERATURES ARE FORECAST THROUGH SATURDAY...GRADUALLY
RETURNING TO NORMAL EARLY NEXT WEEK.

&&

.DISCUSSION...
THUNDERSTORM ACTIVITY HAS RAPIDLY PICKED UP THIS AFTERNOON ACROSS
OUR SOUTHEAST CALIFORNIA ZONES...THE LOWER COLORADO RIVER VALLEY...
AND AS FAR EAST AS CENTRAL LA PAZ AND YUMA COUNTIES. SOME OF THESE
STORMS HAVE QUICKLY CLUSTERED AND EVOLVED TO SEVERE STATUS WITH
STRONG WINDS IN EXCESS 55KT...OTHER ISOLATED STORMS HAVE BEEN
EFFICIENT RAIN PRODUCERS WITH RADAR RAINFALL ESTIMATES OF 1-2 INCHES
PER HOUR.

CLOUD COVER AND COOLER TEMPERATURES ACROSS SOUTH-CENTRAL ARIZONA
CREATED A MORE STABLE ENVIRONMENT AND THUS TOOK A BITE OUT OF THE
CONVECTIVE POTENTIAL THIS AFTERNOON AND HAS KEPT STORM ACTIVITY TO A
MINIMUM SO FAR. THE HIGH AT PHOENIX PEAKED OUT AT 88 DEGREES AND
THAT WAS AT 10 AM THIS MORNING. HOWEVER...AS THE LOW GRADUALLY
SHIFTS EAST...THE COLD CORE 500MB TEMPS/-10 TO 12C/ WILL EVENTUALLY
MOVE OVER SOUTH-CENTRAL ARIZONA...IMPROVING LAPSE RATES/INSTABILITY.
EXPECT SHOWERS/THUNDERSTORMS TO FORM AND EVENTUALLY SPREAD EAST
ACROSS MARICOPA COUNTY/PHOENIX METROPOLITAN AREA BY EARLY
EVENING...CONTINUING INTO THE HIGHER TERRAIN OF SOUTHERN GILA
COUNTY...NORTHERN AND EASTERN ARIZONA BEFORE MIDNIGHT.

THE LOW WILL MOVE MOVE ACROSS THE STATE TONIGHT...THE TROUGH AXIS
EXPECTED TO BE DRAPED ACROSS THE CENTRAL ARIZONA BY LATE FRIDAY
MORNING. MID LEVEL FLOW BEHIND THE DEPARTING TROUGH TURNS SHARPLY
OUT OF THE WEST LATE TONIGHT INTO FRIDAY...SO MOISTURE GETS SCOURED
OUT AND THE FLOW BECOMES LESS FAVORABLE FOR STORMS FRIDAY AFTERNOON.
WOULD ANTICIPATE THAT THE ATMOSPHERE WILL BE PRETTY WORKED OVER AND
MORE STABLE ACROSS OUR ENTIRE FORECAST AREA FROM THIS EVENINGS
ACTIVITY THAT LITTLE IN THE WAY OF CONVECTIVE STORMS WILL
MATERIALIZE FRIDAY. STILL KEEPING SLIGHT CHANCE POPS GOING ACROSS
SOUTHERN GILA COUNTY FOR FRIDAY AFTERNOON...AND MUCH OF THE SAME IS
EXPECTED FOR SATURDAY AND SUNDAY AS LOW LEVEL MIXING RATIOS CONTINUE
TO FALL TO AROUND 5-6 G/KG THIS WEEKEND. DAYTIME TEMPERATURES WILL
CONTINUE TO BE BELOW NORMAL AS WE END THE WEEK...HOLDING IN THE MID
TO UPPER 90S OVER THE LOWER DESERTS FRIDAY AFTERNOON...BARLEY
BREAKING THE 100 DEGREE MARK SATURDAY AFTERNOON...AND A FEW MORE
DEGREES OF WARMING FOR SUNDAY.

THERE IS A GENERAL AGREEMENT AMONG THE OPERATIONAL MODELS AND
ENSEMBLES THAT MOISTURE WILL RETURN TO THE AREA MONDAY/TUESDAY...
ALTHOUGH AT THIS POINT THERE DOES NOT APPEAR TO BE ANY CLEAR SIGNALS
ON WHICH DAY WILL BE ACTIVE. GOING TO RETAIN A LOW-GRADE MONSOON POP
FORECAST EACH AFTERNOON MONDAY THROUGH THURSDAY ALONG WITH NEAR
NORMAL TEMPERATURES.

&&

.AVIATION...
SOUTH-CENTRAL AND SOUTHWEST ARIZONA AND FAR SOUTHEAST CALIFORNIA
INCLUDING KPHX...KIWA...KSDL...KBLH...KIPL...

BATCH OF THICK HIGH CLOUDS IN PLACE EAST OF LOWER COLORADO RIVER
VALLEY EARLY THIS MORNING. CLOUDS WILL THICKEN AS THE MORNING GOES
ON AND SCATTERED SHOWERS WILL BEGIN TO DEVELOP BY 15Z WITH EMBEDDED
THUNDERSTORMS DEVELOPING AFTER 18Z. HELD OFF FOR NOW ON PUTTING
SHRA/TSRA IN TEMPO OR PREVAILING GROUPS OF PHOENIX AREA TAFS AS
AREAL COVERAGE OF SHWRS/TSTMS LOOKS TO BE BEST OVER YUMA AND LA PAZ
COUNTIES. THIS IS CERTAINLY SUBJECT TO CHANGE. TSTMS THAT MANAGE TO
FORM WILL HAVE POTENTIAL TO PRODUCE STRONG WINDS AND SMALL HAIL
ALONG WITH DRAMATICALLY LOWERED VISIBILITY AND CEILING. SURFACE
WINDS WILL BECOME ERRATIC LATER IN THE DAY AS STORM ACTIVITY
DEVELOPS BUT OTHERWISE WILL FAVOR WESTERLY DIRECTIONS OVER PHOENIX
AREA AND SOUTHEASTERLY DIRECTIONS OVER LOWER COLORADO RIVER VALLEY
AND IMPERIAL VALLEY.

AVIATION DISCUSSION NOT UPDATED FOR AMENDED TAFS.

&&

.FIRE WEATHER...
SATURDAY THROUGH WEDNESDAY...
HUMIDITIES TREND DOWNWARD SOME MORE OVER THE WEEKEND BEFORE
REBOUNDING SOME NEXT WEEK. AIR WILL BE DRIEST OVER SOUTHEAST
CALIFORNIA AND HAINES INDEX VALUES CLIMB TO 5 BEFORE IMPROVING BY
TUESDAY. HAINES VALUES WILL BE SIGNIFICANTLY LOWER EAST OF THERE DUE
TO BETTER MOISTURE. OVERNIGHT RECOVERY WILL REMAIN GOOD...LESS SO
OVER SOUTHEAST CALIFORNIA. STORM CHANCES WILL BE SLIGHT AND LIMITED
TO THE HIGHER TERRAIN OF SOUTH-CENTRAL ARIZONA THROUGH
TUESDAY...EXPANDING WESTWARD WEDNESDAY.

&&

.PSR WATCHES/WARNINGS/ADVISORIES...

AZ...NONE.

CA...NONE.

&&

$$

VISIT US ON FACEBOOK...TWITTER...AND AT WEATHER.GOV/PHOENIX

DISCUSSION...MEYERS/LEINS
AVIATION...AJ
FIRE WEATHER...AJ






000
FXUS65 KPSR 212044
AFDPSR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PHOENIX AZ
145 PM MST THU AUG 21 2014

.UPDATE...UPDATED AVIATION DISCUSSION.

&&

.SYNOPSIS...
THERE WILL BE AN INCREASED CHANCE OF SHOWERS AND THUNDERSTORMS
ACROSS THE REGION TODAY AS AN UPPER LEVEL LOW PRESSURE SYSTEM MOVES
THROUGH THE AREA. STORM CHANCES WILL DECREASE FRIDAY AND THROUGH THE
WEEKEND AS DRIER AIR OVERSPREADS THE AREA. BELOW NORMAL TEMPERATURES
ARE FORECAST THROUGH SATURDAY...GRADUALLY RETURNING TO NORMAL EARLY
NEXT WEEK.

&&

.DISCUSSION...
SATELLITE IMAGERY SHOWS A SWATH OF MID-UPPER LEVEL CLOUDS STREAMING
NORTHWARD ACROSS THE STATE THIS MORNING...MOSAIC RADAR DISPLAYING AN
AREA OF SHOWERS AND THUNDERSTORMS THAT HAVE DEVELOPED OVER LA PAZ
AND WESTERN MARICOPA COUNTIES. THIS AREA IS GRADUALLY EXPANDING IN
COVERAGE/AND FILLING IN OVER THE WEST CENTRAL DESERTS AS THE CLOUD
TOPS CONTINUE TO COOL AND THE THICKER BAND OF CLOUD COVER SHIFTS
EAST. SIGNIFICANTLY COLDER TEMPS IN THE UPPER LEVELS OF THE
ATMOSPHERE ARE ALSO NOTED FROM THE 12Z REGIONAL UPPER AIR PLOTS AND
RAOBS...WITH A VERY STEEP LAPSE RATE IN PLACE...AND -10 TO -12C AT
500MB. WITH THE DYNAMICAL SUPPORT PROVIDED BY THE ADVANCING UPPER
LOW JUST OFF THE SAN DIEGO COAST...AND THE CONTINUED MOISTURE
INCREASE WITH PRECIPITABLE WATER NUDGING BACK ABOVE 1.5 INCHES...
STORMS THAT CONTINUE TO FORM IN THIS ENVIRONMENT AS THE DAY
PROGRESSES WILL TEND TO BE MORE ORGANIZED AND SHOW SEVERE
CHARACTERISTICS...NAMELY STRONG DAMAGING WINDS AND LARGE HAIL.
LOCALLY HEAVY RAIN WILL STILL BE POSSIBLE...BUT BASED ON A MORE
PROGRESSIVE STORM MOTION...20-30KT SSW STEERING FLOWS WILL KEEP
STORMS MOVING QUICKLY THROUGH THE AREA...SO THE FLASH FLOOD THREAT
WILL BE LESS AND NOT WIDESPREAD IN NATURE. THE INHERITED FORECAST
GRIDS IN THE NEAR TERM CAPTURE THE CURRENT OBSERVED TRENDS AND
ANALYSIS...NO CHANGES AT THIS TIME.

PREVIOUS DISCUSSION...
AN ACTIVE DAY IS IN STORE FOR THE REGION AS A COMPACT UPPER LOW OVER
SOUTHEAST CALIFORNIA WILL MOVE THROUGH ARIZONA THIS AFTERNOON. EARLY
MORNING WATER VAPOR IMAGERY REVEALS THE LOW CENTERED NEAR SAN DIEGO
THIS MORNING AS OF 08Z...WITH QUITE A BIT OF MOISTURE BEING PULLED
NORTHWARD FROM TROPICAL STORM LOWELL. THIS UPPER TROPOSPHERIC
MOISTURE IS CONFINED MAINLY TO 300MB AND ABOVE BUT PWATS ARE
BEGINNING TO RESPOND PER BLENDED TPW IMAGERY /VALUES IN THE NORTHERN
GULF OF CALIFORNIA HAVE INCREASED TO AROUND 1.5 INCHES SINCE LATE
WEDNESDAY NIGHT/. MEANWHILE...THE REGIONAL RADAR MOSAIC IS BEGINNING
TO SHOW SHOWERS DEVELOPING NEAR ROCKY POINT MOVING NORTHWARD TOWARD
THE AZ BORDER.

PRECIP CHANCES WILL BE ELEVATED EVERYWHERE TODAY AS STRONG DYNAMICAL
SUPPORT ASSOCIATED WITH THE LOW TAKES SHAPE LATER THIS MORNING.
CONFIDENCE IS HIGH THAT MOST LOCATIONS WILL SEE MEASURABLE PRECIP
TODAY...HOWEVER THERE IS STILL QUITE A BIT OF UNCERTAINTY WHERE THE
HEAVIEST RAINFALL BANDS WILL SET UP. STORM MOTIONS WILL BE SLOWEST
ACROSS SOUTHWEST ARIZONA WHERE CORFIDI VECTORS ARE GENERALLY
ADVERTISED AT 10 KNOTS OR LESS. HOWEVER...STORMS WILL LIKELY BE MORE
ORGANIZED FROM PHOENIX EASTWARD GIVEN STRONGER WINDS AND SLIGHTLY
HIGHER MLCAPES. OF COURSE...THE EXTENSIVE BAND OF CLOUD COVER MOVING
THROUGH THE AREA WILL NEED TO THIN OUT QUITE A BIT BEFORE THOSE
ELEVATED MLCAPES ARE REALIZED. BOTTOM LINE...I HAVE RAISED POPS
NEARLY EVERYWHERE FOR TODAY...WITH THE HIGHEST VALUES ACROSS
SOUTHWEST ARIZONA AND PORTIONS OF SOUTHEAST CALIFORNIA...WITH
SLIGHTLY LOWER VALUES AROUND PHOENIX /BUT STILL 3-4 TIMES HIGHER
THAN CLIMO/. I WILL HOLD OFF ISSUING A FLASH FLOOD WATCH THIS
MORNING UNTIL IT BECOMES MORE CLEAR WHERE THE GREATEST FLOOD THREAT
WILL RESIDE. WOULD ALSO FEEL MORE CONFIDENT IF THOSE AFOREMENTIONED
1.5 INCH PWATS MADE THEIR WAY INTO ARIZONA AS OPPOSED TO RIGHT ALONG
THE COAST.

MID LEVEL FLOW BEHIND THE TROUGH TURNS SHARPLY OUT OF THE WEST LATE
TONIGHT INTO FRIDAY...SCOURING OUT QUITE A BIT OF MOISTURE IN THE
PROCESS. GIVEN THE EXPECTED STORM ACTIVITY TODAY AND UNFAVORABLE
FLOW ALOFT ON FRIDAY...MY FEELING IS THAT THINGS SHOULD BE VERY
QUIET FRIDAY AFTERNOON...PERHAPS A FEW SHOWERS EAST OF PHOENIX BUT
NOTHING WIDESPREAD. MUCH OF THE SAME IS EXPECTED FOR SATURDAY AND
SUNDAY AS LOW LEVEL MIXING RATIOS CONTINUE TO FALL TO AROUND 5-6
G/KG THIS WEEKEND.

THERE IS A GENERAL AGREEMENT AMONG THE OPERATIONAL MODELS AND
ENSEMBLES THAT MOISTURE WILL RETURN TO THE AREA
MONDAY/TUESDAY...ALTHOUGH AT THIS POINT THERE DOESNT APPEAR TO BE
ANY CLEAR SIGNALS ON WHICH DAY(S) WILL BE ACTIVE. GOING TO RETAIN A
LOW-GRADE MONSOON POP FORECAST EACH AFTERNOON MONDAY THROUGH
THURSDAY ALONG WITH NEAR NORMAL TEMPERATURES.

&&

.AVIATION...
SOUTH-CENTRAL ARIZONA INCLUDING KPHX...KIWA...AND KSDL...
PERSISTENT CLOUDINESS HAS KEPT TEMPERATURES WELL BELOW NORMAL ACROSS
THE AREA. CONSEQUENTLY...INSTABILITY IS DIMINISHED AND THE THREAT
FOR THUNDERSTORMS HAS DECREASED. HOWEVER...INSTABILITY WILL INCREASE
AGAIN LATE THIS AFTERNOON AND THIS EVENING AS AN AREA OF LOW
PRESSURE MOVES INTO SOUTHWESTERN AZ. ISOLATED TO SCATTERED STORMS
ARE POSSIBLE ACROSS THE PHOENIX AREA...PARTICULARLY IN THE 01Z-05Z
PERIOD. THE STRONGEST STORMS WILL BE CAPABLE OF PRODUCING HEAVY
RAIN...STRONG TO SEVERE WIND GUSTS AND PERHAPS EVEN LARGE HAIL. CIGS
MAY ALSO LOWER TO AROUND 7K FT WITH OCCASIONAL VSBY RESTRICTIONS
BELOW 6SM. CONDITIONS WILL IMPROVE AFTER 06Z WITH A BREAK IN THE
MONSOON ACTIVITY BEGINNING FRIDAY.

SOUTHEAST CALIFORNIA AND SOUTHWEST ARIZONA INCLUDING KIPL AND KBLH...
THUNDERSTORMS WILL CONTINUE TO INCREASE IN COVERAGE THIS AFTERNOON
AT BOTH KIPL AND KBLH. THE STRONGEST STORMS WILL BE CAPABLE OF
PRODUCING HEAVY RAIN...STRONG TO SEVERE WIND GUSTS AND LARGE HAIL.
CIGS MAY ALSO LOWER TO AROUND 6K FT WITH OCCASIONAL VSBY
RESTRICTIONS BELOW 6SM. CONDITIONS WILL IMPROVE AFTER 04Z WITH A
BREAK IN THE MONSOON ACTIVITY BEGINNING FRIDAY.

AVIATION DISCUSSION NOT UPDATED FOR AMENDED TAFS.

&&

.FIRE WEATHER...
SATURDAY THROUGH WEDNESDAY...
HUMIDITIES TREND DOWNWARD SOME MORE OVER THE WEEKEND BEFORE
REBOUNDING SOME NEXT WEEK. AIR WILL BE DRIEST OVER SOUTHEAST
CALIFORNIA AND HAINES INDEX VALUES CLIMB TO 5 BEFORE IMPROVING BY
TUESDAY. HAINES VALUES WILL BE SIGNIFICANTLY LOWER EAST OF THERE DUE
TO BETTER MOISTURE. OVERNIGHT RECOVERY WILL REMAIN GOOD...LESS SO
OVER SOUTHEAST CALIFORNIA. STORM CHANCES WILL BE SLIGHT AND LIMITED
TO THE HIGHER TERRAIN OF SOUTH-CENTRAL ARIZONA THROUGH
TUESDAY...EXPANDING WESTWARD WEDNESDAY.

&&

.PSR WATCHES/WARNINGS/ADVISORIES...

AZ...NONE.

CA...NONE.

&&

$$

VISIT US ON FACEBOOK...TWITTER...AND AT WEATHER.GOV/PHOENIX

DISCUSSION...MEYERS/LEINS
AVIATION...HIRSCH
FIRE WEATHER...AJ






000
FXUS65 KPSR 212044
AFDPSR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PHOENIX AZ
145 PM MST THU AUG 21 2014

.UPDATE...UPDATED AVIATION DISCUSSION.

&&

.SYNOPSIS...
THERE WILL BE AN INCREASED CHANCE OF SHOWERS AND THUNDERSTORMS
ACROSS THE REGION TODAY AS AN UPPER LEVEL LOW PRESSURE SYSTEM MOVES
THROUGH THE AREA. STORM CHANCES WILL DECREASE FRIDAY AND THROUGH THE
WEEKEND AS DRIER AIR OVERSPREADS THE AREA. BELOW NORMAL TEMPERATURES
ARE FORECAST THROUGH SATURDAY...GRADUALLY RETURNING TO NORMAL EARLY
NEXT WEEK.

&&

.DISCUSSION...
SATELLITE IMAGERY SHOWS A SWATH OF MID-UPPER LEVEL CLOUDS STREAMING
NORTHWARD ACROSS THE STATE THIS MORNING...MOSAIC RADAR DISPLAYING AN
AREA OF SHOWERS AND THUNDERSTORMS THAT HAVE DEVELOPED OVER LA PAZ
AND WESTERN MARICOPA COUNTIES. THIS AREA IS GRADUALLY EXPANDING IN
COVERAGE/AND FILLING IN OVER THE WEST CENTRAL DESERTS AS THE CLOUD
TOPS CONTINUE TO COOL AND THE THICKER BAND OF CLOUD COVER SHIFTS
EAST. SIGNIFICANTLY COLDER TEMPS IN THE UPPER LEVELS OF THE
ATMOSPHERE ARE ALSO NOTED FROM THE 12Z REGIONAL UPPER AIR PLOTS AND
RAOBS...WITH A VERY STEEP LAPSE RATE IN PLACE...AND -10 TO -12C AT
500MB. WITH THE DYNAMICAL SUPPORT PROVIDED BY THE ADVANCING UPPER
LOW JUST OFF THE SAN DIEGO COAST...AND THE CONTINUED MOISTURE
INCREASE WITH PRECIPITABLE WATER NUDGING BACK ABOVE 1.5 INCHES...
STORMS THAT CONTINUE TO FORM IN THIS ENVIRONMENT AS THE DAY
PROGRESSES WILL TEND TO BE MORE ORGANIZED AND SHOW SEVERE
CHARACTERISTICS...NAMELY STRONG DAMAGING WINDS AND LARGE HAIL.
LOCALLY HEAVY RAIN WILL STILL BE POSSIBLE...BUT BASED ON A MORE
PROGRESSIVE STORM MOTION...20-30KT SSW STEERING FLOWS WILL KEEP
STORMS MOVING QUICKLY THROUGH THE AREA...SO THE FLASH FLOOD THREAT
WILL BE LESS AND NOT WIDESPREAD IN NATURE. THE INHERITED FORECAST
GRIDS IN THE NEAR TERM CAPTURE THE CURRENT OBSERVED TRENDS AND
ANALYSIS...NO CHANGES AT THIS TIME.

PREVIOUS DISCUSSION...
AN ACTIVE DAY IS IN STORE FOR THE REGION AS A COMPACT UPPER LOW OVER
SOUTHEAST CALIFORNIA WILL MOVE THROUGH ARIZONA THIS AFTERNOON. EARLY
MORNING WATER VAPOR IMAGERY REVEALS THE LOW CENTERED NEAR SAN DIEGO
THIS MORNING AS OF 08Z...WITH QUITE A BIT OF MOISTURE BEING PULLED
NORTHWARD FROM TROPICAL STORM LOWELL. THIS UPPER TROPOSPHERIC
MOISTURE IS CONFINED MAINLY TO 300MB AND ABOVE BUT PWATS ARE
BEGINNING TO RESPOND PER BLENDED TPW IMAGERY /VALUES IN THE NORTHERN
GULF OF CALIFORNIA HAVE INCREASED TO AROUND 1.5 INCHES SINCE LATE
WEDNESDAY NIGHT/. MEANWHILE...THE REGIONAL RADAR MOSAIC IS BEGINNING
TO SHOW SHOWERS DEVELOPING NEAR ROCKY POINT MOVING NORTHWARD TOWARD
THE AZ BORDER.

PRECIP CHANCES WILL BE ELEVATED EVERYWHERE TODAY AS STRONG DYNAMICAL
SUPPORT ASSOCIATED WITH THE LOW TAKES SHAPE LATER THIS MORNING.
CONFIDENCE IS HIGH THAT MOST LOCATIONS WILL SEE MEASURABLE PRECIP
TODAY...HOWEVER THERE IS STILL QUITE A BIT OF UNCERTAINTY WHERE THE
HEAVIEST RAINFALL BANDS WILL SET UP. STORM MOTIONS WILL BE SLOWEST
ACROSS SOUTHWEST ARIZONA WHERE CORFIDI VECTORS ARE GENERALLY
ADVERTISED AT 10 KNOTS OR LESS. HOWEVER...STORMS WILL LIKELY BE MORE
ORGANIZED FROM PHOENIX EASTWARD GIVEN STRONGER WINDS AND SLIGHTLY
HIGHER MLCAPES. OF COURSE...THE EXTENSIVE BAND OF CLOUD COVER MOVING
THROUGH THE AREA WILL NEED TO THIN OUT QUITE A BIT BEFORE THOSE
ELEVATED MLCAPES ARE REALIZED. BOTTOM LINE...I HAVE RAISED POPS
NEARLY EVERYWHERE FOR TODAY...WITH THE HIGHEST VALUES ACROSS
SOUTHWEST ARIZONA AND PORTIONS OF SOUTHEAST CALIFORNIA...WITH
SLIGHTLY LOWER VALUES AROUND PHOENIX /BUT STILL 3-4 TIMES HIGHER
THAN CLIMO/. I WILL HOLD OFF ISSUING A FLASH FLOOD WATCH THIS
MORNING UNTIL IT BECOMES MORE CLEAR WHERE THE GREATEST FLOOD THREAT
WILL RESIDE. WOULD ALSO FEEL MORE CONFIDENT IF THOSE AFOREMENTIONED
1.5 INCH PWATS MADE THEIR WAY INTO ARIZONA AS OPPOSED TO RIGHT ALONG
THE COAST.

MID LEVEL FLOW BEHIND THE TROUGH TURNS SHARPLY OUT OF THE WEST LATE
TONIGHT INTO FRIDAY...SCOURING OUT QUITE A BIT OF MOISTURE IN THE
PROCESS. GIVEN THE EXPECTED STORM ACTIVITY TODAY AND UNFAVORABLE
FLOW ALOFT ON FRIDAY...MY FEELING IS THAT THINGS SHOULD BE VERY
QUIET FRIDAY AFTERNOON...PERHAPS A FEW SHOWERS EAST OF PHOENIX BUT
NOTHING WIDESPREAD. MUCH OF THE SAME IS EXPECTED FOR SATURDAY AND
SUNDAY AS LOW LEVEL MIXING RATIOS CONTINUE TO FALL TO AROUND 5-6
G/KG THIS WEEKEND.

THERE IS A GENERAL AGREEMENT AMONG THE OPERATIONAL MODELS AND
ENSEMBLES THAT MOISTURE WILL RETURN TO THE AREA
MONDAY/TUESDAY...ALTHOUGH AT THIS POINT THERE DOESNT APPEAR TO BE
ANY CLEAR SIGNALS ON WHICH DAY(S) WILL BE ACTIVE. GOING TO RETAIN A
LOW-GRADE MONSOON POP FORECAST EACH AFTERNOON MONDAY THROUGH
THURSDAY ALONG WITH NEAR NORMAL TEMPERATURES.

&&

.AVIATION...
SOUTH-CENTRAL ARIZONA INCLUDING KPHX...KIWA...AND KSDL...
PERSISTENT CLOUDINESS HAS KEPT TEMPERATURES WELL BELOW NORMAL ACROSS
THE AREA. CONSEQUENTLY...INSTABILITY IS DIMINISHED AND THE THREAT
FOR THUNDERSTORMS HAS DECREASED. HOWEVER...INSTABILITY WILL INCREASE
AGAIN LATE THIS AFTERNOON AND THIS EVENING AS AN AREA OF LOW
PRESSURE MOVES INTO SOUTHWESTERN AZ. ISOLATED TO SCATTERED STORMS
ARE POSSIBLE ACROSS THE PHOENIX AREA...PARTICULARLY IN THE 01Z-05Z
PERIOD. THE STRONGEST STORMS WILL BE CAPABLE OF PRODUCING HEAVY
RAIN...STRONG TO SEVERE WIND GUSTS AND PERHAPS EVEN LARGE HAIL. CIGS
MAY ALSO LOWER TO AROUND 7K FT WITH OCCASIONAL VSBY RESTRICTIONS
BELOW 6SM. CONDITIONS WILL IMPROVE AFTER 06Z WITH A BREAK IN THE
MONSOON ACTIVITY BEGINNING FRIDAY.

SOUTHEAST CALIFORNIA AND SOUTHWEST ARIZONA INCLUDING KIPL AND KBLH...
THUNDERSTORMS WILL CONTINUE TO INCREASE IN COVERAGE THIS AFTERNOON
AT BOTH KIPL AND KBLH. THE STRONGEST STORMS WILL BE CAPABLE OF
PRODUCING HEAVY RAIN...STRONG TO SEVERE WIND GUSTS AND LARGE HAIL.
CIGS MAY ALSO LOWER TO AROUND 6K FT WITH OCCASIONAL VSBY
RESTRICTIONS BELOW 6SM. CONDITIONS WILL IMPROVE AFTER 04Z WITH A
BREAK IN THE MONSOON ACTIVITY BEGINNING FRIDAY.

AVIATION DISCUSSION NOT UPDATED FOR AMENDED TAFS.

&&

.FIRE WEATHER...
SATURDAY THROUGH WEDNESDAY...
HUMIDITIES TREND DOWNWARD SOME MORE OVER THE WEEKEND BEFORE
REBOUNDING SOME NEXT WEEK. AIR WILL BE DRIEST OVER SOUTHEAST
CALIFORNIA AND HAINES INDEX VALUES CLIMB TO 5 BEFORE IMPROVING BY
TUESDAY. HAINES VALUES WILL BE SIGNIFICANTLY LOWER EAST OF THERE DUE
TO BETTER MOISTURE. OVERNIGHT RECOVERY WILL REMAIN GOOD...LESS SO
OVER SOUTHEAST CALIFORNIA. STORM CHANCES WILL BE SLIGHT AND LIMITED
TO THE HIGHER TERRAIN OF SOUTH-CENTRAL ARIZONA THROUGH
TUESDAY...EXPANDING WESTWARD WEDNESDAY.

&&

.PSR WATCHES/WARNINGS/ADVISORIES...

AZ...NONE.

CA...NONE.

&&

$$

VISIT US ON FACEBOOK...TWITTER...AND AT WEATHER.GOV/PHOENIX

DISCUSSION...MEYERS/LEINS
AVIATION...HIRSCH
FIRE WEATHER...AJ







000
FXUS65 KPSR 211636
AFDPSR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PHOENIX AZ
935 AM MST THU AUG 21 2014

.SYNOPSIS...
THERE WILL BE AN INCREASED CHANCE OF SHOWERS AND THUNDERSTORMS
ACROSS THE REGION TODAY AS AN UPPER LEVEL LOW PRESSURE SYSTEM MOVES
THROUGH THE AREA. STORM CHANCES WILL DECREASE FRIDAY AND THROUGH THE
WEEKEND AS DRIER AIR OVERSPREADS THE AREA. BELOW NORMAL TEMPERATURES
ARE FORECAST THROUGH SATURDAY...GRADUALLY RETURNING TO NORMAL EARLY
NEXT WEEK.

&&

.DISCUSSION...
SATELLITE IMAGERY SHOWS A SWATH OF MID-UPPER LEVEL CLOUDS STREAMING
NORTHWARD ACROSS THE STATE THIS MORNING...MOSAIC RADAR DISPLAYING AN
AREA OF SHOWERS AND THUNDERSTORMS THAT HAVE DEVELOPED OVER LA PAZ
AND WESTERN MARICOPA COUNTIES. THIS AREA IS GRADUALLY EXPANDING IN
COVERAGE/AND FILLING IN OVER THE WEST CENTRAL DESERTS AS THE CLOUD
TOPS CONTINUE TO COOL AND THE THICKER BAND OF CLOUD COVER SHIFTS
EAST. SIGNIFICANTLY COLDER TEMPS IN THE UPPER LEVELS OF THE
ATMOSPHERE ARE ALSO NOTED FROM THE 12Z REGIONAL UPPER AIR PLOTS AND
RAOBS...WITH A VERY STEEP LAPSE RATE IN PLACE...AND -10 TO -12C AT
500MB. WITH THE DYNAMICAL SUPPORT PROVIDED BY THE ADVANCING UPPER
LOW JUST OFF THE SAN DIEGO COAST...AND THE CONTINUED MOISTURE
INCREASE WITH PRECIPITABLE WATER NUDGING BACK ABOVE 1.5 INCHES...
STORMS THAT CONTINUE TO FORM IN THIS ENVIRONMENT AS THE DAY
PROGRESSES WILL TEND TO BE MORE ORGANIZED AND SHOW SEVERE
CHARACTERISTICS...NAMELY STRONG DAMAGING WINDS AND LARGE HAIL.
LOCALLY HEAVY RAIN WILL STILL BE POSSIBLE...BUT BASED ON A MORE
PROGRESSIVE STORM MOTION...20-30KT SSW STEERING FLOWS WILL KEEP
STORMS MOVING QUICKLY THROUGH THE AREA...SO THE FLASH FLOOD THREAT
WILL BE LESS AND NOT WIDESPREAD IN NATURE. THE INHERITED FORECAST
GRIDS IN THE NEAR TERM CAPTURE THE CURRENT OBSERVED TRENDS AND
ANALYSIS...NO CHANGES AT THIS TIME.

PREVIOUS DISCUSSION...
AN ACTIVE DAY IS IN STORE FOR THE REGION AS A COMPACT UPPER LOW OVER
SOUTHEAST CALIFORNIA WILL MOVE THROUGH ARIZONA THIS AFTERNOON. EARLY
MORNING WATER VAPOR IMAGERY REVEALS THE LOW CENTERED NEAR SAN DIEGO
THIS MORNING AS OF 08Z...WITH QUITE A BIT OF MOISTURE BEING PULLED
NORTHWARD FROM TROPICAL STORM LOWELL. THIS UPPER TROPOSPHERIC
MOISTURE IS CONFINED MAINLY TO 300MB AND ABOVE BUT PWATS ARE
BEGINNING TO RESPOND PER BLENDED TPW IMAGERY /VALUES IN THE NORTHERN
GULF OF CALIFORNIA HAVE INCREASED TO AROUND 1.5 INCHES SINCE LATE
WEDNESDAY NIGHT/. MEANWHILE...THE REGIONAL RADAR MOSAIC IS BEGINNING
TO SHOW SHOWERS DEVELOPING NEAR ROCKY POINT MOVING NORTHWARD TOWARD
THE AZ BORDER.

PRECIP CHANCES WILL BE ELEVATED EVERYWHERE TODAY AS STRONG DYNAMICAL
SUPPORT ASSOCIATED WITH THE LOW TAKES SHAPE LATER THIS MORNING.
CONFIDENCE IS HIGH THAT MOST LOCATIONS WILL SEE MEASURABLE PRECIP
TODAY...HOWEVER THERE IS STILL QUITE A BIT OF UNCERTAINTY WHERE THE
HEAVIEST RAINFALL BANDS WILL SET UP. STORM MOTIONS WILL BE SLOWEST
ACROSS SOUTHWEST ARIZONA WHERE CORFIDI VECTORS ARE GENERALLY
ADVERTISED AT 10 KNOTS OR LESS. HOWEVER...STORMS WILL LIKELY BE MORE
ORGANIZED FROM PHOENIX EASTWARD GIVEN STRONGER WINDS AND SLIGHTLY
HIGHER MLCAPES. OF COURSE...THE EXTENSIVE BAND OF CLOUD COVER MOVING
THROUGH THE AREA WILL NEED TO THIN OUT QUITE A BIT BEFORE THOSE
ELEVATED MLCAPES ARE REALIZED. BOTTOM LINE...I HAVE RAISED POPS
NEARLY EVERYWHERE FOR TODAY...WITH THE HIGHEST VALUES ACROSS
SOUTHWEST ARIZONA AND PORTIONS OF SOUTHEAST CALIFORNIA...WITH
SLIGHTLY LOWER VALUES AROUND PHOENIX /BUT STILL 3-4 TIMES HIGHER
THAN CLIMO/. I WILL HOLD OFF ISSUING A FLASH FLOOD WATCH THIS
MORNING UNTIL IT BECOMES MORE CLEAR WHERE THE GREATEST FLOOD THREAT
WILL RESIDE. WOULD ALSO FEEL MORE CONFIDENT IF THOSE AFOREMENTIONED
1.5 INCH PWATS MADE THEIR WAY INTO ARIZONA AS OPPOSED TO RIGHT ALONG
THE COAST.

MID LEVEL FLOW BEHIND THE TROUGH TURNS SHARPLY OUT OF THE WEST LATE
TONIGHT INTO FRIDAY...SCOURING OUT QUITE A BIT OF MOISTURE IN THE
PROCESS. GIVEN THE EXPECTED STORM ACTIVITY TODAY AND UNFAVORABLE
FLOW ALOFT ON FRIDAY...MY FEELING IS THAT THINGS SHOULD BE VERY
QUIET FRIDAY AFTERNOON...PERHAPS A FEW SHOWERS EAST OF PHOENIX BUT
NOTHING WIDESPREAD. MUCH OF THE SAME IS EXPECTED FOR SATURDAY AND
SUNDAY AS LOW LEVEL MIXING RATIOS CONTINUE TO FALL TO AROUND 5-6
G/KG THIS WEEKEND.

THERE IS A GENERAL AGREEMENT AMONG THE OPERATIONAL MODELS AND
ENSEMBLES THAT MOISTURE WILL RETURN TO THE AREA
MONDAY/TUESDAY...ALTHOUGH AT THIS POINT THERE DOESNT APPEAR TO BE
ANY CLEAR SIGNALS ON WHICH DAY(S) WILL BE ACTIVE. GOING TO RETAIN A
LOW-GRADE MONSOON POP FORECAST EACH AFTERNOON MONDAY THROUGH
THURSDAY ALONG WITH NEAR NORMAL TEMPERATURES.

&&

.AVIATION...
SOUTH-CENTRAL AND SOUTHWEST ARIZONA AND FAR SOUTHEAST CALIFORNIA
INCLUDING KPHX...KIWA...KSDL...KBLH...KIPL...

BATCH OF THICK HIGH CLOUDS IN PLACE EAST OF LOWER COLORADO RIVER
VALLEY EARLY THIS MORNING. CLOUDS WILL THICKEN AS THE MORNING GOES
ON AND SCATTERED SHOWERS WILL BEGIN TO DEVELOP BY 15Z WITH EMBEDDED
THUNDERSTORMS DEVELOPING AFTER 18Z. HELD OFF FOR NOW ON PUTTING
SHRA/TSRA IN TEMPO OR PREVAILING GROUPS OF PHOENIX AREA TAFS AS
AREAL COVERAGE OF SHWRS/TSTMS LOOKS TO BE BEST OVER YUMA AND LA PAZ
COUNTIES. THIS IS CERTAINLY SUBJECT TO CHANGE. TSTMS THAT MANAGE TO
FORM WILL HAVE POTENTIAL TO PRODUCE STRONG WINDS AND SMALL HAIL
ALONG WITH DRAMATICALLY LOWERED VISIBILITY AND CEILING. SURFACE
WINDS WILL BECOME ERRATIC LATER IN THE DAY AS STORM ACTIVITY
DEVELOPS BUT OTHERWISE WILL FAVOR WESTERLY DIRECTIONS OVER PHOENIX
AREA AND SOUTHEASTERLY DIRECTIONS OVER LOWER COLORADO RIVER VALLEY
AND IMPERIAL VALLEY.

AVIATION DISCUSSION NOT UPDATED FOR AMENDED TAFS.

&&

.FIRE WEATHER...
SATURDAY THROUGH WEDNESDAY...
HUMIDITIES TREND DOWNWARD SOME MORE OVER THE WEEKEND BEFORE
REBOUNDING SOME NEXT WEEK. AIR WILL BE DRIEST OVER SOUTHEAST
CALIFORNIA AND HAINES INDEX VALUES CLIMB TO 5 BEFORE IMPROVING BY
TUESDAY. HAINES VALUES WILL BE SIGNIFICANTLY LOWER EAST OF THERE DUE
TO BETTER MOISTURE. OVERNIGHT RECOVERY WILL REMAIN GOOD...LESS SO
OVER SOUTHEAST CALIFORNIA. STORM CHANCES WILL BE SLIGHT AND LIMITED
TO THE HIGHER TERRAIN OF SOUTH-CENTRAL ARIZONA THROUGH
TUESDAY...EXPANDING WESTWARD WEDNESDAY.

&&

.PSR WATCHES/WARNINGS/ADVISORIES...

AZ...NONE.

CA...NONE.

&&

$$

VISIT US ON FACEBOOK...TWITTER...AND AT WEATHER.GOV/PHOENIX

DISCUSSION...MEYERS/LEINS
AVIATION...AJ
FIRE WEATHER...AJ






000
FXUS65 KPSR 211636
AFDPSR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PHOENIX AZ
935 AM MST THU AUG 21 2014

.SYNOPSIS...
THERE WILL BE AN INCREASED CHANCE OF SHOWERS AND THUNDERSTORMS
ACROSS THE REGION TODAY AS AN UPPER LEVEL LOW PRESSURE SYSTEM MOVES
THROUGH THE AREA. STORM CHANCES WILL DECREASE FRIDAY AND THROUGH THE
WEEKEND AS DRIER AIR OVERSPREADS THE AREA. BELOW NORMAL TEMPERATURES
ARE FORECAST THROUGH SATURDAY...GRADUALLY RETURNING TO NORMAL EARLY
NEXT WEEK.

&&

.DISCUSSION...
SATELLITE IMAGERY SHOWS A SWATH OF MID-UPPER LEVEL CLOUDS STREAMING
NORTHWARD ACROSS THE STATE THIS MORNING...MOSAIC RADAR DISPLAYING AN
AREA OF SHOWERS AND THUNDERSTORMS THAT HAVE DEVELOPED OVER LA PAZ
AND WESTERN MARICOPA COUNTIES. THIS AREA IS GRADUALLY EXPANDING IN
COVERAGE/AND FILLING IN OVER THE WEST CENTRAL DESERTS AS THE CLOUD
TOPS CONTINUE TO COOL AND THE THICKER BAND OF CLOUD COVER SHIFTS
EAST. SIGNIFICANTLY COLDER TEMPS IN THE UPPER LEVELS OF THE
ATMOSPHERE ARE ALSO NOTED FROM THE 12Z REGIONAL UPPER AIR PLOTS AND
RAOBS...WITH A VERY STEEP LAPSE RATE IN PLACE...AND -10 TO -12C AT
500MB. WITH THE DYNAMICAL SUPPORT PROVIDED BY THE ADVANCING UPPER
LOW JUST OFF THE SAN DIEGO COAST...AND THE CONTINUED MOISTURE
INCREASE WITH PRECIPITABLE WATER NUDGING BACK ABOVE 1.5 INCHES...
STORMS THAT CONTINUE TO FORM IN THIS ENVIRONMENT AS THE DAY
PROGRESSES WILL TEND TO BE MORE ORGANIZED AND SHOW SEVERE
CHARACTERISTICS...NAMELY STRONG DAMAGING WINDS AND LARGE HAIL.
LOCALLY HEAVY RAIN WILL STILL BE POSSIBLE...BUT BASED ON A MORE
PROGRESSIVE STORM MOTION...20-30KT SSW STEERING FLOWS WILL KEEP
STORMS MOVING QUICKLY THROUGH THE AREA...SO THE FLASH FLOOD THREAT
WILL BE LESS AND NOT WIDESPREAD IN NATURE. THE INHERITED FORECAST
GRIDS IN THE NEAR TERM CAPTURE THE CURRENT OBSERVED TRENDS AND
ANALYSIS...NO CHANGES AT THIS TIME.

PREVIOUS DISCUSSION...
AN ACTIVE DAY IS IN STORE FOR THE REGION AS A COMPACT UPPER LOW OVER
SOUTHEAST CALIFORNIA WILL MOVE THROUGH ARIZONA THIS AFTERNOON. EARLY
MORNING WATER VAPOR IMAGERY REVEALS THE LOW CENTERED NEAR SAN DIEGO
THIS MORNING AS OF 08Z...WITH QUITE A BIT OF MOISTURE BEING PULLED
NORTHWARD FROM TROPICAL STORM LOWELL. THIS UPPER TROPOSPHERIC
MOISTURE IS CONFINED MAINLY TO 300MB AND ABOVE BUT PWATS ARE
BEGINNING TO RESPOND PER BLENDED TPW IMAGERY /VALUES IN THE NORTHERN
GULF OF CALIFORNIA HAVE INCREASED TO AROUND 1.5 INCHES SINCE LATE
WEDNESDAY NIGHT/. MEANWHILE...THE REGIONAL RADAR MOSAIC IS BEGINNING
TO SHOW SHOWERS DEVELOPING NEAR ROCKY POINT MOVING NORTHWARD TOWARD
THE AZ BORDER.

PRECIP CHANCES WILL BE ELEVATED EVERYWHERE TODAY AS STRONG DYNAMICAL
SUPPORT ASSOCIATED WITH THE LOW TAKES SHAPE LATER THIS MORNING.
CONFIDENCE IS HIGH THAT MOST LOCATIONS WILL SEE MEASURABLE PRECIP
TODAY...HOWEVER THERE IS STILL QUITE A BIT OF UNCERTAINTY WHERE THE
HEAVIEST RAINFALL BANDS WILL SET UP. STORM MOTIONS WILL BE SLOWEST
ACROSS SOUTHWEST ARIZONA WHERE CORFIDI VECTORS ARE GENERALLY
ADVERTISED AT 10 KNOTS OR LESS. HOWEVER...STORMS WILL LIKELY BE MORE
ORGANIZED FROM PHOENIX EASTWARD GIVEN STRONGER WINDS AND SLIGHTLY
HIGHER MLCAPES. OF COURSE...THE EXTENSIVE BAND OF CLOUD COVER MOVING
THROUGH THE AREA WILL NEED TO THIN OUT QUITE A BIT BEFORE THOSE
ELEVATED MLCAPES ARE REALIZED. BOTTOM LINE...I HAVE RAISED POPS
NEARLY EVERYWHERE FOR TODAY...WITH THE HIGHEST VALUES ACROSS
SOUTHWEST ARIZONA AND PORTIONS OF SOUTHEAST CALIFORNIA...WITH
SLIGHTLY LOWER VALUES AROUND PHOENIX /BUT STILL 3-4 TIMES HIGHER
THAN CLIMO/. I WILL HOLD OFF ISSUING A FLASH FLOOD WATCH THIS
MORNING UNTIL IT BECOMES MORE CLEAR WHERE THE GREATEST FLOOD THREAT
WILL RESIDE. WOULD ALSO FEEL MORE CONFIDENT IF THOSE AFOREMENTIONED
1.5 INCH PWATS MADE THEIR WAY INTO ARIZONA AS OPPOSED TO RIGHT ALONG
THE COAST.

MID LEVEL FLOW BEHIND THE TROUGH TURNS SHARPLY OUT OF THE WEST LATE
TONIGHT INTO FRIDAY...SCOURING OUT QUITE A BIT OF MOISTURE IN THE
PROCESS. GIVEN THE EXPECTED STORM ACTIVITY TODAY AND UNFAVORABLE
FLOW ALOFT ON FRIDAY...MY FEELING IS THAT THINGS SHOULD BE VERY
QUIET FRIDAY AFTERNOON...PERHAPS A FEW SHOWERS EAST OF PHOENIX BUT
NOTHING WIDESPREAD. MUCH OF THE SAME IS EXPECTED FOR SATURDAY AND
SUNDAY AS LOW LEVEL MIXING RATIOS CONTINUE TO FALL TO AROUND 5-6
G/KG THIS WEEKEND.

THERE IS A GENERAL AGREEMENT AMONG THE OPERATIONAL MODELS AND
ENSEMBLES THAT MOISTURE WILL RETURN TO THE AREA
MONDAY/TUESDAY...ALTHOUGH AT THIS POINT THERE DOESNT APPEAR TO BE
ANY CLEAR SIGNALS ON WHICH DAY(S) WILL BE ACTIVE. GOING TO RETAIN A
LOW-GRADE MONSOON POP FORECAST EACH AFTERNOON MONDAY THROUGH
THURSDAY ALONG WITH NEAR NORMAL TEMPERATURES.

&&

.AVIATION...
SOUTH-CENTRAL AND SOUTHWEST ARIZONA AND FAR SOUTHEAST CALIFORNIA
INCLUDING KPHX...KIWA...KSDL...KBLH...KIPL...

BATCH OF THICK HIGH CLOUDS IN PLACE EAST OF LOWER COLORADO RIVER
VALLEY EARLY THIS MORNING. CLOUDS WILL THICKEN AS THE MORNING GOES
ON AND SCATTERED SHOWERS WILL BEGIN TO DEVELOP BY 15Z WITH EMBEDDED
THUNDERSTORMS DEVELOPING AFTER 18Z. HELD OFF FOR NOW ON PUTTING
SHRA/TSRA IN TEMPO OR PREVAILING GROUPS OF PHOENIX AREA TAFS AS
AREAL COVERAGE OF SHWRS/TSTMS LOOKS TO BE BEST OVER YUMA AND LA PAZ
COUNTIES. THIS IS CERTAINLY SUBJECT TO CHANGE. TSTMS THAT MANAGE TO
FORM WILL HAVE POTENTIAL TO PRODUCE STRONG WINDS AND SMALL HAIL
ALONG WITH DRAMATICALLY LOWERED VISIBILITY AND CEILING. SURFACE
WINDS WILL BECOME ERRATIC LATER IN THE DAY AS STORM ACTIVITY
DEVELOPS BUT OTHERWISE WILL FAVOR WESTERLY DIRECTIONS OVER PHOENIX
AREA AND SOUTHEASTERLY DIRECTIONS OVER LOWER COLORADO RIVER VALLEY
AND IMPERIAL VALLEY.

AVIATION DISCUSSION NOT UPDATED FOR AMENDED TAFS.

&&

.FIRE WEATHER...
SATURDAY THROUGH WEDNESDAY...
HUMIDITIES TREND DOWNWARD SOME MORE OVER THE WEEKEND BEFORE
REBOUNDING SOME NEXT WEEK. AIR WILL BE DRIEST OVER SOUTHEAST
CALIFORNIA AND HAINES INDEX VALUES CLIMB TO 5 BEFORE IMPROVING BY
TUESDAY. HAINES VALUES WILL BE SIGNIFICANTLY LOWER EAST OF THERE DUE
TO BETTER MOISTURE. OVERNIGHT RECOVERY WILL REMAIN GOOD...LESS SO
OVER SOUTHEAST CALIFORNIA. STORM CHANCES WILL BE SLIGHT AND LIMITED
TO THE HIGHER TERRAIN OF SOUTH-CENTRAL ARIZONA THROUGH
TUESDAY...EXPANDING WESTWARD WEDNESDAY.

&&

.PSR WATCHES/WARNINGS/ADVISORIES...

AZ...NONE.

CA...NONE.

&&

$$

VISIT US ON FACEBOOK...TWITTER...AND AT WEATHER.GOV/PHOENIX

DISCUSSION...MEYERS/LEINS
AVIATION...AJ
FIRE WEATHER...AJ







000
FXUS65 KPSR 211247 AAA
AFDPSR

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE PHOENIX AZ
545 AM MST THU AUG 21 2014

.UPDATE...
UPDATED AVIATION AND FIRE WEATHER SECTIONS.

&&

.SYNOPSIS...
THERE WILL BE AN INCREASED CHANCE OF SHOWERS AND THUNDERSTORMS
ACROSS THE REGION TODAY AS AN UPPER LEVEL LOW PRESSURE SYSTEM MOVES
THROUGH THE AREA. STORM CHANCES WILL DECREASE FRIDAY THROUGH THE
WEEKEND AS DRIER AIR MOVES IN FROM THE WEST. BELOW NORMAL
TEMPERATURES ARE FORECAST THROUGH SATURDAY...GRADUALLY RETURNING TO
NORMAL EARLY NEXT WEEK.

&&

.DISCUSSION...
AN ACTIVE DAY IS IN STORE FOR THE REGION AS A COMPACT UPPER LOW OVER
SOUTHEAST CALIFORNIA WILL MOVE THROUGH ARIZONA THIS AFTERNOON. EARLY
MORNING WATER VAPOR IMAGERY REVEALS THE LOW CENTERED NEAR SAN DIEGO
THIS MORNING AS OF 08Z...WITH QUITE A BIT OF MOISTURE BEING PULLED
NORTHWARD FROM TROPICAL STORM LOWELL. THIS UPPER TROPOSPHERIC
MOISTURE IS CONFINED MAINLY TO 300MB AND ABOVE BUT PWATS ARE
BEGINNING TO RESPOND PER BLENDED TPW IMAGERY /VALUES IN THE NORTHERN
GULF OF CALIFORNIA HAVE INCREASED TO AROUND 1.5 INCHES SINCE LATE
WEDNESDAY NIGHT/. MEANWHILE...THE REGIONAL RADAR MOSAIC IS BEGINNING
TO SHOW SHOWERS DEVELOPING NEAR ROCKY POINT MOVING NORTHWARD TOWARD
THE AZ BORDER.

PRECIP CHANCES WILL BE ELEVATED EVERYWHERE TODAY AS STRONG DYNAMICAL
SUPPORT ASSOCIATED WITH THE LOW TAKES SHAPE LATER THIS MORNING.
CONFIDENCE IS HIGH THAT MOST LOCATIONS WILL SEE MEASURABLE PRECIP
TODAY...HOWEVER THERE IS STILL QUITE A BIT OF UNCERTAINTY WHERE THE
HEAVIEST RAINFALL BANDS WILL SET UP. STORM MOTIONS WILL BE SLOWEST
ACROSS SOUTHWEST ARIZONA WHERE CORFIDI VECTORS ARE GENERALLY
ADVERTISED AT 10 KNOTS OR LESS. HOWEVER...STORMS WILL LIKELY BE MORE
ORGANIZED FROM PHOENIX EASTWARD GIVEN STRONGER WINDS AND SLIGHTLY
HIGHER MLCAPES. OF COURSE...THE EXTENSIVE BAND OF CLOUD COVER MOVING
THROUGH THE AREA WILL NEED TO THIN OUT QUITE A BIT BEFORE THOSE
ELEVATED MLCAPES ARE REALIZED. BOTTOM LINE...I HAVE RAISED POPS
NEARLY EVERYWHERE FOR TODAY...WITH THE HIGHEST VALUES ACROSS
SOUTHWEST ARIZONA AND PORTIONS OF SOUTHEAST CALIFORNIA...WITH
SLIGHTLY LOWER VALUES AROUND PHOENIX /BUT STILL 3-4 TIMES HIGHER
THAN CLIMO/. I WILL HOLD OFF ISSUING A FLASH FLOOD WATCH THIS
MORNING UNTIL IT BECOMES MORE CLEAR WHERE THE GREATEST FLOOD THREAT
WILL RESIDE. WOULD ALSO FEEL MORE CONFIDENT IF THOSE AFOREMENTIONED
1.5 INCH PWATS MADE THEIR WAY INTO ARIZONA AS OPPOSED TO RIGHT ALONG
THE COAST.

MID LEVEL FLOW BEHIND THE TROUGH TURNS SHARPLY OUT OF THE WEST LATE
TONIGHT INTO FRIDAY...SCOURING OUT QUITE A BIT OF MOISTURE IN THE
PROCESS. GIVEN THE EXPECTED STORM ACTIVITY TODAY AND UNFAVORABLE
FLOW ALOFT ON FRIDAY...MY FEELING IS THAT THINGS SHOULD BE VERY
QUIET FRIDAY AFTERNOON...PERHAPS A FEW SHOWERS EAST OF PHOENIX BUT
NOTHING WIDESPREAD. MUCH OF THE SAME IS EXPECTED FOR SATURDAY AND
SUNDAY AS LOW LEVEL MIXING RATIOS CONTINUE TO FALL TO AROUND 5-6
G/KG THIS WEEKEND.

THERE IS A GENERAL AGREEMENT AMONG THE OPERATIONAL MODELS AND
ENSEMBLES THAT MOISTURE WILL RETURN TO THE AREA
MONDAY/TUESDAY...ALTHOUGH AT THIS POINT THERE DOESNT APPEAR TO BE
ANY CLEAR SIGNALS ON WHICH DAY(S) WILL BE ACTIVE. GOING TO RETAIN A
LOW-GRADE MONSOON POP FORECAST EACH AFTERNOON MONDAY THROUGH
THURSDAY ALONG WITH NEAR NORMAL TEMPERATURES.

&&

.AVIATION...
SOUTH-CENTRAL AND SOUTHWEST ARIZONA AND FAR SOUTHEAST CALIFORNIA
INCLUDING KPHX...KIWA...KSDL...KBLH...KIPL...

BATCH OF THICK HIGH CLOUDS IN PLACE EAST OF LOWER COLORADO RIVER
VALLEY EARLY THIS MORNING. CLOUDS WILL THICKEN AS THE MORNING GOES
ON AND SCATTERED SHOWERS WILL BEGIN TO DEVELOP BY 15Z WITH EMBEDDED
THUNDERSTORMS DEVELOPING AFTER 18Z. HELD OFF FOR NOW ON PUTTING
SHRA/TSRA IN TEMPO OR PREVAILING GROUPS OF PHOENIX AREA TAFS AS
AREAL COVERAGE OF SHWRS/TSTMS LOOKS TO BE BEST OVER YUMA AND LA PAZ
COUNTIES. THIS IS CERTAINLY SUBJECT TO CHANGE. TSTMS THAT MANAGE TO
FORM WILL HAVE POTENTIAL TO PRODUCE STRONG WINDS AND SMALL HAIL
ALONG WITH DRAMATICALLY LOWERED VISIBILITY AND CEILING. SURFACE
WINDS WILL BECOME ERRATIC LATER IN THE DAY AS STORM ACTIVITY
DEVELOPS BUT OTHERWISE WILL FAVOR WESTERLY DIRECTIONS OVER PHOENIX
AREA AND SOUTHEASTERLY DIRECTIONS OVER LOWER COLORADO RIVER VALLEY
AND IMPERIAL VALLEY.

AVIATION DISCUSSION NOT UPDATED FOR AMENDED TAFS.

&&

.FIRE WEATHER...
SATURDAY THROUGH WEDNESDAY...
HUMIDITIES TREND DOWNWARD SOME MORE OVER THE WEEKEND BEFORE
REBOUNDING SOME NEXT WEEK. AIR WILL BE DRIEST OVER SOUTHEAST
CALIFORNIA AND HAINES INDEX VALUES CLIMB TO 5 BEFORE IMPROVING BY
TUESDAY. HAINES VALUES WILL BE SIGNIFICANTLY LOWER EAST OF THERE DUE
TO BETTER MOISTURE. OVERNIGHT RECOVERY WILL REMAIN GOOD...LESS SO
OVER SOUTHEAST CALIFORNIA. STORM CHANCES WILL BE SLIGHT AND LIMITED
TO THE HIGHER TERRAIN OF SOUTH-CENTRAL ARIZONA THROUGH
TUESDAY...EXPANDING WESTWARD WEDNESDAY.

&&

.PSR WATCHES/WARNINGS/ADVISORIES...

AZ...NONE.

CA...NONE.

&&

$$

VISIT US ON FACEBOOK...TWITTER...AND AT WEATHER.GOV/PHOENIX

DISCUSSION...LEINS
AVIATION...AJ
FIRE WEATHER...AJ







000
FXUS65 KPSR 211247 AAA
AFDPSR

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE PHOENIX AZ
545 AM MST THU AUG 21 2014

.UPDATE...
UPDATED AVIATION AND FIRE WEATHER SECTIONS.

&&

.SYNOPSIS...
THERE WILL BE AN INCREASED CHANCE OF SHOWERS AND THUNDERSTORMS
ACROSS THE REGION TODAY AS AN UPPER LEVEL LOW PRESSURE SYSTEM MOVES
THROUGH THE AREA. STORM CHANCES WILL DECREASE FRIDAY THROUGH THE
WEEKEND AS DRIER AIR MOVES IN FROM THE WEST. BELOW NORMAL
TEMPERATURES ARE FORECAST THROUGH SATURDAY...GRADUALLY RETURNING TO
NORMAL EARLY NEXT WEEK.

&&

.DISCUSSION...
AN ACTIVE DAY IS IN STORE FOR THE REGION AS A COMPACT UPPER LOW OVER
SOUTHEAST CALIFORNIA WILL MOVE THROUGH ARIZONA THIS AFTERNOON. EARLY
MORNING WATER VAPOR IMAGERY REVEALS THE LOW CENTERED NEAR SAN DIEGO
THIS MORNING AS OF 08Z...WITH QUITE A BIT OF MOISTURE BEING PULLED
NORTHWARD FROM TROPICAL STORM LOWELL. THIS UPPER TROPOSPHERIC
MOISTURE IS CONFINED MAINLY TO 300MB AND ABOVE BUT PWATS ARE
BEGINNING TO RESPOND PER BLENDED TPW IMAGERY /VALUES IN THE NORTHERN
GULF OF CALIFORNIA HAVE INCREASED TO AROUND 1.5 INCHES SINCE LATE
WEDNESDAY NIGHT/. MEANWHILE...THE REGIONAL RADAR MOSAIC IS BEGINNING
TO SHOW SHOWERS DEVELOPING NEAR ROCKY POINT MOVING NORTHWARD TOWARD
THE AZ BORDER.

PRECIP CHANCES WILL BE ELEVATED EVERYWHERE TODAY AS STRONG DYNAMICAL
SUPPORT ASSOCIATED WITH THE LOW TAKES SHAPE LATER THIS MORNING.
CONFIDENCE IS HIGH THAT MOST LOCATIONS WILL SEE MEASURABLE PRECIP
TODAY...HOWEVER THERE IS STILL QUITE A BIT OF UNCERTAINTY WHERE THE
HEAVIEST RAINFALL BANDS WILL SET UP. STORM MOTIONS WILL BE SLOWEST
ACROSS SOUTHWEST ARIZONA WHERE CORFIDI VECTORS ARE GENERALLY
ADVERTISED AT 10 KNOTS OR LESS. HOWEVER...STORMS WILL LIKELY BE MORE
ORGANIZED FROM PHOENIX EASTWARD GIVEN STRONGER WINDS AND SLIGHTLY
HIGHER MLCAPES. OF COURSE...THE EXTENSIVE BAND OF CLOUD COVER MOVING
THROUGH THE AREA WILL NEED TO THIN OUT QUITE A BIT BEFORE THOSE
ELEVATED MLCAPES ARE REALIZED. BOTTOM LINE...I HAVE RAISED POPS
NEARLY EVERYWHERE FOR TODAY...WITH THE HIGHEST VALUES ACROSS
SOUTHWEST ARIZONA AND PORTIONS OF SOUTHEAST CALIFORNIA...WITH
SLIGHTLY LOWER VALUES AROUND PHOENIX /BUT STILL 3-4 TIMES HIGHER
THAN CLIMO/. I WILL HOLD OFF ISSUING A FLASH FLOOD WATCH THIS
MORNING UNTIL IT BECOMES MORE CLEAR WHERE THE GREATEST FLOOD THREAT
WILL RESIDE. WOULD ALSO FEEL MORE CONFIDENT IF THOSE AFOREMENTIONED
1.5 INCH PWATS MADE THEIR WAY INTO ARIZONA AS OPPOSED TO RIGHT ALONG
THE COAST.

MID LEVEL FLOW BEHIND THE TROUGH TURNS SHARPLY OUT OF THE WEST LATE
TONIGHT INTO FRIDAY...SCOURING OUT QUITE A BIT OF MOISTURE IN THE
PROCESS. GIVEN THE EXPECTED STORM ACTIVITY TODAY AND UNFAVORABLE
FLOW ALOFT ON FRIDAY...MY FEELING IS THAT THINGS SHOULD BE VERY
QUIET FRIDAY AFTERNOON...PERHAPS A FEW SHOWERS EAST OF PHOENIX BUT
NOTHING WIDESPREAD. MUCH OF THE SAME IS EXPECTED FOR SATURDAY AND
SUNDAY AS LOW LEVEL MIXING RATIOS CONTINUE TO FALL TO AROUND 5-6
G/KG THIS WEEKEND.

THERE IS A GENERAL AGREEMENT AMONG THE OPERATIONAL MODELS AND
ENSEMBLES THAT MOISTURE WILL RETURN TO THE AREA
MONDAY/TUESDAY...ALTHOUGH AT THIS POINT THERE DOESNT APPEAR TO BE
ANY CLEAR SIGNALS ON WHICH DAY(S) WILL BE ACTIVE. GOING TO RETAIN A
LOW-GRADE MONSOON POP FORECAST EACH AFTERNOON MONDAY THROUGH
THURSDAY ALONG WITH NEAR NORMAL TEMPERATURES.

&&

.AVIATION...
SOUTH-CENTRAL AND SOUTHWEST ARIZONA AND FAR SOUTHEAST CALIFORNIA
INCLUDING KPHX...KIWA...KSDL...KBLH...KIPL...

BATCH OF THICK HIGH CLOUDS IN PLACE EAST OF LOWER COLORADO RIVER
VALLEY EARLY THIS MORNING. CLOUDS WILL THICKEN AS THE MORNING GOES
ON AND SCATTERED SHOWERS WILL BEGIN TO DEVELOP BY 15Z WITH EMBEDDED
THUNDERSTORMS DEVELOPING AFTER 18Z. HELD OFF FOR NOW ON PUTTING
SHRA/TSRA IN TEMPO OR PREVAILING GROUPS OF PHOENIX AREA TAFS AS
AREAL COVERAGE OF SHWRS/TSTMS LOOKS TO BE BEST OVER YUMA AND LA PAZ
COUNTIES. THIS IS CERTAINLY SUBJECT TO CHANGE. TSTMS THAT MANAGE TO
FORM WILL HAVE POTENTIAL TO PRODUCE STRONG WINDS AND SMALL HAIL
ALONG WITH DRAMATICALLY LOWERED VISIBILITY AND CEILING. SURFACE
WINDS WILL BECOME ERRATIC LATER IN THE DAY AS STORM ACTIVITY
DEVELOPS BUT OTHERWISE WILL FAVOR WESTERLY DIRECTIONS OVER PHOENIX
AREA AND SOUTHEASTERLY DIRECTIONS OVER LOWER COLORADO RIVER VALLEY
AND IMPERIAL VALLEY.

AVIATION DISCUSSION NOT UPDATED FOR AMENDED TAFS.

&&

.FIRE WEATHER...
SATURDAY THROUGH WEDNESDAY...
HUMIDITIES TREND DOWNWARD SOME MORE OVER THE WEEKEND BEFORE
REBOUNDING SOME NEXT WEEK. AIR WILL BE DRIEST OVER SOUTHEAST
CALIFORNIA AND HAINES INDEX VALUES CLIMB TO 5 BEFORE IMPROVING BY
TUESDAY. HAINES VALUES WILL BE SIGNIFICANTLY LOWER EAST OF THERE DUE
TO BETTER MOISTURE. OVERNIGHT RECOVERY WILL REMAIN GOOD...LESS SO
OVER SOUTHEAST CALIFORNIA. STORM CHANCES WILL BE SLIGHT AND LIMITED
TO THE HIGHER TERRAIN OF SOUTH-CENTRAL ARIZONA THROUGH
TUESDAY...EXPANDING WESTWARD WEDNESDAY.

&&

.PSR WATCHES/WARNINGS/ADVISORIES...

AZ...NONE.

CA...NONE.

&&

$$

VISIT US ON FACEBOOK...TWITTER...AND AT WEATHER.GOV/PHOENIX

DISCUSSION...LEINS
AVIATION...AJ
FIRE WEATHER...AJ








000
FXUS65 KPSR 210848
AFDPSR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PHOENIX AZ
148 AM MST THU AUG 21 2014

.SYNOPSIS...
THERE WILL BE AN INCREASED CHANCE OF SHOWERS AND THUNDERSTORMS
ACROSS THE REGION TODAY AS AN UPPER LEVEL LOW PRESSURE SYSTEM MOVES
THROUGH THE AREA. STORM CHANCES WILL DECREASE FRIDAY THROUGH THE
WEEKEND AS DRIER AIR MOVES IN FROM THE WEST. BELOW NORMAL
TEMPERATURES ARE FORECAST THROUGH SATURDAY...GRADUALLY RETURNING TO
NORMAL EARLY NEXT WEEK.

&&

.DISCUSSION...
AN ACTIVE DAY IS IN STORE FOR THE REGION AS A COMPACT UPPER LOW OVER
SOUTHEAST CALIFORNIA WILL MOVE THROUGH ARIZONA THIS AFTERNOON. EARLY
MORNING WATER VAPOR IMAGERY REVEALS THE LOW CENTERED NEAR SAN DIEGO
THIS MORNING AS OF 08Z...WITH QUITE A BIT OF MOISTURE BEING PULLED
NORTHWARD FROM TROPICAL STORM LOWELL. THIS UPPER TROPOSPHERIC
MOISTURE IS CONFINED MAINLY TO 300MB AND ABOVE BUT PWATS ARE
BEGINNING TO RESPOND PER BLENDED TPW IMAGERY /VALUES IN THE NORTHERN
GULF OF CALIFORNIA HAVE INCREASED TO AROUND 1.5 INCHES SINCE LATE
WEDNESDAY NIGHT/. MEANWHILE...THE REGIONAL RADAR MOSAIC IS BEGINNING
TO SHOW SHOWERS DEVELOPING NEAR ROCKY POINT MOVING NORTHWARD TOWARD
THE AZ BORDER.

PRECIP CHANCES WILL BE ELEVATED EVERYWHERE TODAY AS STRONG DYNAMICAL
SUPPORT ASSOCIATED WITH THE LOW TAKES SHAPE LATER THIS MORNING.
CONFIDENCE IS HIGH THAT MOST LOCATIONS WILL SEE MEASURABLE PRECIP
TODAY...HOWEVER THERE IS STILL QUITE A BIT OF UNCERTAINTY WHERE THE
HEAVIEST RAINFALL BANDS WILL SET UP. STORM MOTIONS WILL BE SLOWEST
ACROSS SOUTHWEST ARIZONA WHERE CORFIDI VECTORS ARE GENERALLY
ADVERTISED AT 10 KNOTS OR LESS. HOWEVER...STORMS WILL LIKELY BE MORE
ORGANIZED FROM PHOENIX EASTWARD GIVEN STRONGER WINDS AND SLIGHTLY
HIGHER MLCAPES. OF COURSE...THE EXTENSIVE BAND OF CLOUD COVER MOVING
THROUGH THE AREA WILL NEED TO THIN OUT QUITE A BIT BEFORE THOSE
ELEVATED MLCAPES ARE REALIZED. BOTTOM LINE...I HAVE RAISED POPS
NEARLY EVERYWHERE FOR TODAY...WITH THE HIGHEST VALUES ACROSS
SOUTHWEST ARIZONA AND PORTIONS OF SOUTHEAST CALIFORNIA...WITH
SLIGHTLY LOWER VALUES AROUND PHOENIX /BUT STILL 3-4 TIMES HIGHER
THAN CLIMO/. I WILL HOLD OFF ISSUING A FLASH FLOOD WATCH THIS
MORNING UNTIL IT BECOMES MORE CLEAR WHERE THE GREATEST FLOOD THREAT
WILL RESIDE. WOULD ALSO FEEL MORE CONFIDENT IF THOSE AFOREMENTIONED
1.5 INCH PWATS MADE THEIR WAY INTO ARIZONA AS OPPOSED TO RIGHT ALONG
THE COAST.

MID LEVEL FLOW BEHIND THE TROUGH TURNS SHARPLY OUT OF THE WEST LATE
TONIGHT INTO FRIDAY...SCOURING OUT QUITE A BIT OF MOISTURE IN THE
PROCESS. GIVEN THE EXPECTED STORM ACTIVITY TODAY AND UNFAVORABLE
FLOW ALOFT ON FRIDAY...MY FEELING IS THAT THINGS SHOULD BE VERY
QUIET FRIDAY AFTERNOON...PERHAPS A FEW SHOWERS EAST OF PHOENIX BUT
NOTHING WIDESPREAD. MUCH OF THE SAME IS EXPECTED FOR SATURDAY AND
SUNDAY AS LOW LEVEL MIXING RATIOS CONTINUE TO FALL TO AROUND 5-6
G/KG THIS WEEKEND.

THERE IS A GENERAL AGREEMENT AMONG THE OPERATIONAL MODELS AND
ENSEMBLES THAT MOISTURE WILL RETURN TO THE AREA
MONDAY/TUESDAY...ALTHOUGH AT THIS POINT THERE DOESNT APPEAR TO BE
ANY CLEAR SIGNALS ON WHICH DAY(S) WILL BE ACTIVE. GOING TO RETAIN A
LOW-GRADE MONSOON POP FORECAST EACH AFTERNOON MONDAY THROUGH
THURSDAY ALONG WITH NEAR NORMAL TEMPERATURES.

&&

.AVIATION...
SOUTH-CENTRAL ARIZONA INCLUDING KPHX...KIWA...AND KSDL...

LINGERING SHOWER AND THUNDERSTORM ACTIVITY TO THE WEST OF PHOENIX
WILL GRADUALLY PUSH NORTHWARD BY LATE EVENING...BUT SOME OUTFLOWS
WILL KEEP WESTERLY WINDS ACROSS THE PHOENIX AREA FOR A FEW MORE
HOURS BEFORE DOWNSLOPE EASTERLIES TAKE OVER. CIG LEVELS WILL
GRADUALLY LOWER THROUGH NOON THURSDAY TO AROUND 15K FEET. THERE IS
LOW TO MEDIUM CONFIDENCE OF SOME LIGHT SHOWERS OR VIRGA
AFFECTING AREA TERMINALS SOMETIME BETWEEN 12Z-18Z. AFTERNOON AND
EVENING STORM CHANCES ARE EXPECTED TO MAINLY BE FOCUSED ACROSS
SOUTHWEST ARIZONA...BUT CAN/T RULE OUT A FEW STORMS AFFECTING AREA
TERMINALS LATE THURSDAY AFTERNOON AND EARLY EVENING. EVEN THOUGH
CONFIDENCE IN THESE STORMS IS FAIRLY LOW AT THIS POINT...GUSTY
OUTFLOW WINDS AFFECTING TERMINALS WILL BE THE MORE LIKELY THREAT.

SOUTHWEST ARIZONA AND SOUTHEAST CALIFORNIA INCLUDING KIPL AND KBLH...

UPPER LEVEL LOW WILL PUSH THROUGH THE REGION TONIGHT INTO THURSDAY
WITH A PERIOD OF MORNING SHOWERS AND ISOLATED THUNDERSTORMS POSSIBLE
AROUND 12Z. ADDITIONAL STORM DEVELOPMENT IS EXPECTED DURING THE
AFTERNOON ON THURSDAY...MAINLY ACROSS THE LOWER COLORADO RIVER
VALLEY AND SOUTHWEST ARIZONA. FAIRLY CONFIDENT GUSTY OUTFLOW WINDS
WILL AFFECT KBLH SOMETIME MID TO LATE AFTERNOON THURSDAY...WITH A
LOWER POTENTIAL FOR THUNDERSTORM RAINS AFFECTING THE TERMINAL.

AVIATION DISCUSSION NOT UPDATED FOR AMENDED TAFS.

&&

.FIRE WEATHER...
FRIDAY THROUGH TUESDAY...
STORM CHANCES BEGIN TRENDING DOWNWARD FRIDAY THROUGH EARLY NEXT WEEK
AS WESTERLY FLOW ALOFT TAKES HOLD ACROSS THE AREA. SLIGHTLY DRIER
AIR WILL MOVE INTO THE REGION FROM THE WEST WHICH SHOULD RESULT IN
STORMS IN THE MORE CLIMATOLOGICALLY FAVORED AREAS EAST OF PHOENIX.
LOOKS TO BE A LOW-GRADE MONSOON THROUGH EARLY NEXT WEEK. HUMIDITIES
WILL REMAIN SOMEWHAT ELEVATED WITH FAIR TO GOOD OVERNIGHT RECOVERIES
EXPECTED. WINDS WILL FAVOR TYPICAL DIURNAL DIRECTIONS.

&&

.PSR WATCHES/WARNINGS/ADVISORIES...

AZ...NONE.

CA...NONE.

&&

$$

VISIT US ON FACEBOOK...TWITTER...AND AT WEATHER.GOV/PHOENIX

DISCUSSION...LEINS
AVIATION...KUHLMAN
FIRE WEATHER...LEINS







000
FXUS65 KPSR 210848
AFDPSR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PHOENIX AZ
148 AM MST THU AUG 21 2014

.SYNOPSIS...
THERE WILL BE AN INCREASED CHANCE OF SHOWERS AND THUNDERSTORMS
ACROSS THE REGION TODAY AS AN UPPER LEVEL LOW PRESSURE SYSTEM MOVES
THROUGH THE AREA. STORM CHANCES WILL DECREASE FRIDAY THROUGH THE
WEEKEND AS DRIER AIR MOVES IN FROM THE WEST. BELOW NORMAL
TEMPERATURES ARE FORECAST THROUGH SATURDAY...GRADUALLY RETURNING TO
NORMAL EARLY NEXT WEEK.

&&

.DISCUSSION...
AN ACTIVE DAY IS IN STORE FOR THE REGION AS A COMPACT UPPER LOW OVER
SOUTHEAST CALIFORNIA WILL MOVE THROUGH ARIZONA THIS AFTERNOON. EARLY
MORNING WATER VAPOR IMAGERY REVEALS THE LOW CENTERED NEAR SAN DIEGO
THIS MORNING AS OF 08Z...WITH QUITE A BIT OF MOISTURE BEING PULLED
NORTHWARD FROM TROPICAL STORM LOWELL. THIS UPPER TROPOSPHERIC
MOISTURE IS CONFINED MAINLY TO 300MB AND ABOVE BUT PWATS ARE
BEGINNING TO RESPOND PER BLENDED TPW IMAGERY /VALUES IN THE NORTHERN
GULF OF CALIFORNIA HAVE INCREASED TO AROUND 1.5 INCHES SINCE LATE
WEDNESDAY NIGHT/. MEANWHILE...THE REGIONAL RADAR MOSAIC IS BEGINNING
TO SHOW SHOWERS DEVELOPING NEAR ROCKY POINT MOVING NORTHWARD TOWARD
THE AZ BORDER.

PRECIP CHANCES WILL BE ELEVATED EVERYWHERE TODAY AS STRONG DYNAMICAL
SUPPORT ASSOCIATED WITH THE LOW TAKES SHAPE LATER THIS MORNING.
CONFIDENCE IS HIGH THAT MOST LOCATIONS WILL SEE MEASURABLE PRECIP
TODAY...HOWEVER THERE IS STILL QUITE A BIT OF UNCERTAINTY WHERE THE
HEAVIEST RAINFALL BANDS WILL SET UP. STORM MOTIONS WILL BE SLOWEST
ACROSS SOUTHWEST ARIZONA WHERE CORFIDI VECTORS ARE GENERALLY
ADVERTISED AT 10 KNOTS OR LESS. HOWEVER...STORMS WILL LIKELY BE MORE
ORGANIZED FROM PHOENIX EASTWARD GIVEN STRONGER WINDS AND SLIGHTLY
HIGHER MLCAPES. OF COURSE...THE EXTENSIVE BAND OF CLOUD COVER MOVING
THROUGH THE AREA WILL NEED TO THIN OUT QUITE A BIT BEFORE THOSE
ELEVATED MLCAPES ARE REALIZED. BOTTOM LINE...I HAVE RAISED POPS
NEARLY EVERYWHERE FOR TODAY...WITH THE HIGHEST VALUES ACROSS
SOUTHWEST ARIZONA AND PORTIONS OF SOUTHEAST CALIFORNIA...WITH
SLIGHTLY LOWER VALUES AROUND PHOENIX /BUT STILL 3-4 TIMES HIGHER
THAN CLIMO/. I WILL HOLD OFF ISSUING A FLASH FLOOD WATCH THIS
MORNING UNTIL IT BECOMES MORE CLEAR WHERE THE GREATEST FLOOD THREAT
WILL RESIDE. WOULD ALSO FEEL MORE CONFIDENT IF THOSE AFOREMENTIONED
1.5 INCH PWATS MADE THEIR WAY INTO ARIZONA AS OPPOSED TO RIGHT ALONG
THE COAST.

MID LEVEL FLOW BEHIND THE TROUGH TURNS SHARPLY OUT OF THE WEST LATE
TONIGHT INTO FRIDAY...SCOURING OUT QUITE A BIT OF MOISTURE IN THE
PROCESS. GIVEN THE EXPECTED STORM ACTIVITY TODAY AND UNFAVORABLE
FLOW ALOFT ON FRIDAY...MY FEELING IS THAT THINGS SHOULD BE VERY
QUIET FRIDAY AFTERNOON...PERHAPS A FEW SHOWERS EAST OF PHOENIX BUT
NOTHING WIDESPREAD. MUCH OF THE SAME IS EXPECTED FOR SATURDAY AND
SUNDAY AS LOW LEVEL MIXING RATIOS CONTINUE TO FALL TO AROUND 5-6
G/KG THIS WEEKEND.

THERE IS A GENERAL AGREEMENT AMONG THE OPERATIONAL MODELS AND
ENSEMBLES THAT MOISTURE WILL RETURN TO THE AREA
MONDAY/TUESDAY...ALTHOUGH AT THIS POINT THERE DOESNT APPEAR TO BE
ANY CLEAR SIGNALS ON WHICH DAY(S) WILL BE ACTIVE. GOING TO RETAIN A
LOW-GRADE MONSOON POP FORECAST EACH AFTERNOON MONDAY THROUGH
THURSDAY ALONG WITH NEAR NORMAL TEMPERATURES.

&&

.AVIATION...
SOUTH-CENTRAL ARIZONA INCLUDING KPHX...KIWA...AND KSDL...

LINGERING SHOWER AND THUNDERSTORM ACTIVITY TO THE WEST OF PHOENIX
WILL GRADUALLY PUSH NORTHWARD BY LATE EVENING...BUT SOME OUTFLOWS
WILL KEEP WESTERLY WINDS ACROSS THE PHOENIX AREA FOR A FEW MORE
HOURS BEFORE DOWNSLOPE EASTERLIES TAKE OVER. CIG LEVELS WILL
GRADUALLY LOWER THROUGH NOON THURSDAY TO AROUND 15K FEET. THERE IS
LOW TO MEDIUM CONFIDENCE OF SOME LIGHT SHOWERS OR VIRGA
AFFECTING AREA TERMINALS SOMETIME BETWEEN 12Z-18Z. AFTERNOON AND
EVENING STORM CHANCES ARE EXPECTED TO MAINLY BE FOCUSED ACROSS
SOUTHWEST ARIZONA...BUT CAN/T RULE OUT A FEW STORMS AFFECTING AREA
TERMINALS LATE THURSDAY AFTERNOON AND EARLY EVENING. EVEN THOUGH
CONFIDENCE IN THESE STORMS IS FAIRLY LOW AT THIS POINT...GUSTY
OUTFLOW WINDS AFFECTING TERMINALS WILL BE THE MORE LIKELY THREAT.

SOUTHWEST ARIZONA AND SOUTHEAST CALIFORNIA INCLUDING KIPL AND KBLH...

UPPER LEVEL LOW WILL PUSH THROUGH THE REGION TONIGHT INTO THURSDAY
WITH A PERIOD OF MORNING SHOWERS AND ISOLATED THUNDERSTORMS POSSIBLE
AROUND 12Z. ADDITIONAL STORM DEVELOPMENT IS EXPECTED DURING THE
AFTERNOON ON THURSDAY...MAINLY ACROSS THE LOWER COLORADO RIVER
VALLEY AND SOUTHWEST ARIZONA. FAIRLY CONFIDENT GUSTY OUTFLOW WINDS
WILL AFFECT KBLH SOMETIME MID TO LATE AFTERNOON THURSDAY...WITH A
LOWER POTENTIAL FOR THUNDERSTORM RAINS AFFECTING THE TERMINAL.

AVIATION DISCUSSION NOT UPDATED FOR AMENDED TAFS.

&&

.FIRE WEATHER...
FRIDAY THROUGH TUESDAY...
STORM CHANCES BEGIN TRENDING DOWNWARD FRIDAY THROUGH EARLY NEXT WEEK
AS WESTERLY FLOW ALOFT TAKES HOLD ACROSS THE AREA. SLIGHTLY DRIER
AIR WILL MOVE INTO THE REGION FROM THE WEST WHICH SHOULD RESULT IN
STORMS IN THE MORE CLIMATOLOGICALLY FAVORED AREAS EAST OF PHOENIX.
LOOKS TO BE A LOW-GRADE MONSOON THROUGH EARLY NEXT WEEK. HUMIDITIES
WILL REMAIN SOMEWHAT ELEVATED WITH FAIR TO GOOD OVERNIGHT RECOVERIES
EXPECTED. WINDS WILL FAVOR TYPICAL DIURNAL DIRECTIONS.

&&

.PSR WATCHES/WARNINGS/ADVISORIES...

AZ...NONE.

CA...NONE.

&&

$$

VISIT US ON FACEBOOK...TWITTER...AND AT WEATHER.GOV/PHOENIX

DISCUSSION...LEINS
AVIATION...KUHLMAN
FIRE WEATHER...LEINS






000
FXUS65 KPSR 210409
AFDPSR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PHOENIX AZ
909 PM MST WED AUG 20 2014

.SYNOPSIS...
CHANCES OF STORM ACTIVITY INCREASE ON THURSDAY AS AN UPPER LOW
PRESSURE SYSTEM ALONG THE CALIFORNIA COAST MOVES TOWARDS THE DESERT
SOUTHWEST. DRIER AIR SPREADING IN FROM THE WEST WILL REDUCE
THUNDERSTORM ACTIVITY FROM THIS WEEKEND INTO EARLY NEXT WEEK. BELOW
NORMAL TEMPERATURES ARE FORECAST FROM TODAY THROUGH FRIDAY...WARMING
THIS WEEKEND.

&&

.DISCUSSION...
STORM ACTIVITY TODAY HAS BEEN FOCUSED IN A SOMEWHAT FAVORABLE AREA
OF ACCENT TO THE EAST OF A CLOSED LOW CURRENTLY SITUATED NEAR SAN
DIEGO. INITIALLY...STORMS FIRED OVER THE HIGH TERRAIN AREAS OF
SOUTHERN MARICOPA...NORTHERN YUMA...AND LA PAZ COUNTIES WITH THE LA
PAZ STORM ACTIVITY PRODUCING THE MOST ORGANIZED STORMS. EVEN THOUGH
PWATS ARE MUCH LOWER THAN THE PREVIOUS FEW DAYS...SLOW MOVING AND
SOME BACK BUILDING STORMS ALLOWED FOR A FEW AREAS IN LA PAZ COUNTY
TO SEE SOME HEAVY RAINFALL AND MINOR FLASH FLOODING. SHOWERS AND
THUNDERSTORMS CONTINUE TO MOVE NORTHWARD THROUGH CENTRAL LA PAZ AND
NORTHWEST MARICOPA COUNTIES...ON THE NOSE OF STRONG UPPER LEVEL
MOISTURE ADVECTION. MODELS SHOW THIS MOISTURE SURGE QUITE
WELL...MAINLY FOCUSED ABOVE 15K FEET THROUGH 15Z THURSDAY. ONCE THIS
CURRENT ACTIVITY MOVES NORTHWARD OUT OF OUR CWA BY AROUND 06Z...WE
SHOULD HAVE A BREAK IN THE RAIN THROUGH MUCH OF THE OVERNIGHT. MAY
END UP SEEING SOME LIGHT HIGH BASED SHOWERS OR VIRGA DEVELOP
SOMETIME AFTER DAYBREAK THURSDAY ACROSS SOUTHWEST AND SOUTH-CENTRAL
ARIZONA IN RESPONSE TO THE MOISTURE SURGE AND MODERATE ACCENT AHEAD
OF THE UPPER LEVEL LOW. EXTENSIVE MID AND HIGH LEVEL CLOUD BAND WILL
GRADUALLY SHIFT EASTWARD THROUGH ARIZONA DURING THE DAY
THURSDAY...LEAVING QUITE A BIT OF SUNSHINE FOR THE LOWER COLORADO
RIVER VALLEY AND MUCH OF SOUTHWEST ARIZONA BEFORE STORMS REDEVELOP
BY EARLY TO MID AFTERNOON. HAVE MADE SOME MINOR FORECAST ADJUSTMENTS
FOR TONIGHT...LOWERING POPS TO ONLY 10 PERCENT WEST OF PHOENIX.

&&

.PREVIOUS DISCUSSION...
THE UPPER LOW WILL DRIFT TO A FAVORABLE POSITION THURSDAY
MORNING. VORTICITY FORCED ASCENT WILL INCREASE AHEAD OF THE LOW AND
SHOWERS ARE EXPECTED TO DEVELOP ACROSS SE AZ AND SW AZ THURSDAY
MORNING. LAPSE RATES WILL STEEPEN DURING THE AFTERNOON AS THE
MID-LEVEL COLD POOL (500 MB TEMPERATURES AS LOW AS -11C) TRANSLATES
EASTWARD. ADDITIONAL ASCENT ASSOCIATED WITH THE RIGHT REAR QUADRANT
OF AN ANOMALOUSLY STRONG JET STREAK WILL SUPPORT ADDITIONAL
CONVECTION ACROSS CENTRAL AZ...MAINLY DURING THE AFTERNOON AND EARLY
EVENING. SOME STORMS WILL AGAIN HAVE THE POTENTIAL TO PRODUCE HEAVY
RAIN...GUSTY WINDS...SMALL HAIL AND LOCALIZED FLOODING. BULK SHEAR
MAGNITUDES ALSO SUGGEST THE POTENTIAL FOR ORGANIZED STORMS CAPABLE
OF PRODUCING SEVERE STORMS...MAINLY FROM PHOENIX EASTWARD.

FRIDAY...
ON FRIDAY THE LOW TRACKS ACROSS ARIZONA AND WEAKENS IN THE PROCESS
WITH DRIER AIR MOVING IN BEHIND IT. THUS POPS TREND DOWNWARD FRIDAY.
TEMPERATURES WILL BE NEAR OR SOMEWHAT BELOW NORMAL THROUGH FRIDAY.

SATURDAY THROUGH TUESDAY...
MODELS SHOW AN INCREASE IN MOISTURE BEHIND THE DEPARTING LOW WITH
POSSIBLY SOME TANGENTIAL INFLUENCE FROM WHAT IS NOW T.S. LOWELL. GFS
SHOWS MORE BROAD TROUGHING OVER THE WESTERN STATES THAN DOES THE
ECWMF WHICH HAS THE RIDGE AXIS FURTHER A BIT FURTHER NORTH THROUGH
MONDAY. AS A RESULT...ECWMF HAS MORE MOISTURE AROUND. ON TUESDAY AND
WEDNESDAY...BOTH MODELS BRING A NORTHEAST PACIFIC RIDGE
INLAND...ECMWF IS MORE AMPLIFIED. MEANWHILE...BOTH MODELS CONTINUE
TO DEPICT YET ANOTHER TROPICAL STORM OFF SOUTHERN BAJA AND DEEPER
MOISTURE OVER OUR FORECAST AREA. IT REMAINS TO BE SEEN JUST HOW THE
MOISTURE PLAYS OUT. HELD ON TO LOW GRADE MONSOON SCENARIO...SLIGHT
CHANCE POPS LIMITED TO SOUTH-CENTRAL ARIZONA...WITH SUBTLE WESTWARD
EXPANSION OF POPS FOR WEDNESDAY.

&&

.AVIATION...
SOUTH-CENTRAL ARIZONA INCLUDING KPHX...KIWA...AND KSDL...

LINGERING SHOWER AND THUNDERSTORM ACTIVITY TO THE WEST OF PHOENIX
WILL GRADUALLY PUSH NORTHWARD BY LATE EVENING...BUT SOME OUTFLOWS
WILL KEEP WESTERLY WINDS ACROSS THE PHOENIX AREA FOR A FEW MORE
HOURS BEFORE DOWNSLOPE EASTERLIES TAKE OVER. CIG LEVELS WILL
GRADUALLY LOWER THROUGH NOON THURSDAY TO AROUND 15K FEET. THERE IS
LOW TO MEDIUM CONFIDENCE OF SOME LIGHT SHOWERS OR VIRGA
AFFECTING AREA TERMINALS SOMETIME BETWEEN 12Z-18Z. AFTERNOON AND
EVENING STORM CHANCES ARE EXPECTED TO MAINLY BE FOCUSED ACROSS
SOUTHWEST ARIZONA...BUT CAN/T RULE OUT A FEW STORMS AFFECTING AREA
TERMINALS LATE THURSDAY AFTERNOON AND EARLY EVENING. EVEN THOUGH
CONFIDENCE IN THESE STORMS IS FAIRLY LOW AT THIS POINT...GUSTY
OUTFLOW WINDS AFFECTING TERMINALS WILL BE THE MORE LIKELY THREAT.

SOUTHWEST ARIZONA AND SOUTHEAST CALIFORNIA INCLUDING KIPL AND KBLH...

UPPER LEVEL LOW WILL PUSH THROUGH THE REGION TONIGHT INTO THURSDAY
WITH A PERIOD OF MORNING SHOWERS AND ISOLATED THUNDERSTORMS POSSIBLE
AROUND 12Z. ADDITIONAL STORM DEVELOPMENT IS EXPECTED DURING THE
AFTERNOON ON THURSDAY...MAINLY ACROSS THE LOWER COLORADO RIVER
VALLEY AND SOUTHWEST ARIZONA. FAIRLY CONFIDENT GUSTY OUTFLOW WINDS
WILL AFFECT KBLH SOMETIME MID TO LATE AFTERNOON THURSDAY...WITH A
LOWER POTENTIAL FOR THUNDERSTORM RAINS AFFECTING THE TERMINAL.

AVIATION DISCUSSION NOT UPDATED FOR AMENDED TAFS.

&&

.FIRE WEATHER...
FRIDAY THROUGH TUESDAY...
STORM CHANCES BEGIN TRENDING DOWNWARD FRIDAY THROUGH EARLY NEXT WEEK
AS WESTERLY FLOW ALOFT TAKES HOLD ACROSS THE AREA. SLIGHTLY DRIER
AIR WILL MOVE INTO THE REGION FROM THE WEST WHICH SHOULD RESULT IN
STORMS IN THE MORE CLIMATOLOGICALLY FAVORED AREAS EAST OF PHOENIX.
LOOKS TO BE A LOW-GRADE MONSOON THROUGH EARLY NEXT WEEK. HUMIDITIES
WILL REMAIN SOMEWHAT ELEVATED WITH FAIR TO GOOD OVERNIGHT RECOVERIES
EXPECTED. WINDS WILL FAVOR TYPICAL DIURNAL DIRECTIONS.

&&

.PSR WATCHES/WARNINGS/ADVISORIES...

AZ...NONE.

CA...NONE.

&&

$$

VISIT US ON FACEBOOK...TWITTER...AND AT WEATHER.GOV/PHOENIX

DISCUSSION...KUHLMAN
PREVIOUS DISCUSSION...HIRSCH/AJ
AVIATION...KUHLMAN
FIRE WEATHER...LEINS










000
FXUS65 KPSR 210409
AFDPSR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PHOENIX AZ
909 PM MST WED AUG 20 2014

.SYNOPSIS...
CHANCES OF STORM ACTIVITY INCREASE ON THURSDAY AS AN UPPER LOW
PRESSURE SYSTEM ALONG THE CALIFORNIA COAST MOVES TOWARDS THE DESERT
SOUTHWEST. DRIER AIR SPREADING IN FROM THE WEST WILL REDUCE
THUNDERSTORM ACTIVITY FROM THIS WEEKEND INTO EARLY NEXT WEEK. BELOW
NORMAL TEMPERATURES ARE FORECAST FROM TODAY THROUGH FRIDAY...WARMING
THIS WEEKEND.

&&

.DISCUSSION...
STORM ACTIVITY TODAY HAS BEEN FOCUSED IN A SOMEWHAT FAVORABLE AREA
OF ACCENT TO THE EAST OF A CLOSED LOW CURRENTLY SITUATED NEAR SAN
DIEGO. INITIALLY...STORMS FIRED OVER THE HIGH TERRAIN AREAS OF
SOUTHERN MARICOPA...NORTHERN YUMA...AND LA PAZ COUNTIES WITH THE LA
PAZ STORM ACTIVITY PRODUCING THE MOST ORGANIZED STORMS. EVEN THOUGH
PWATS ARE MUCH LOWER THAN THE PREVIOUS FEW DAYS...SLOW MOVING AND
SOME BACK BUILDING STORMS ALLOWED FOR A FEW AREAS IN LA PAZ COUNTY
TO SEE SOME HEAVY RAINFALL AND MINOR FLASH FLOODING. SHOWERS AND
THUNDERSTORMS CONTINUE TO MOVE NORTHWARD THROUGH CENTRAL LA PAZ AND
NORTHWEST MARICOPA COUNTIES...ON THE NOSE OF STRONG UPPER LEVEL
MOISTURE ADVECTION. MODELS SHOW THIS MOISTURE SURGE QUITE
WELL...MAINLY FOCUSED ABOVE 15K FEET THROUGH 15Z THURSDAY. ONCE THIS
CURRENT ACTIVITY MOVES NORTHWARD OUT OF OUR CWA BY AROUND 06Z...WE
SHOULD HAVE A BREAK IN THE RAIN THROUGH MUCH OF THE OVERNIGHT. MAY
END UP SEEING SOME LIGHT HIGH BASED SHOWERS OR VIRGA DEVELOP
SOMETIME AFTER DAYBREAK THURSDAY ACROSS SOUTHWEST AND SOUTH-CENTRAL
ARIZONA IN RESPONSE TO THE MOISTURE SURGE AND MODERATE ACCENT AHEAD
OF THE UPPER LEVEL LOW. EXTENSIVE MID AND HIGH LEVEL CLOUD BAND WILL
GRADUALLY SHIFT EASTWARD THROUGH ARIZONA DURING THE DAY
THURSDAY...LEAVING QUITE A BIT OF SUNSHINE FOR THE LOWER COLORADO
RIVER VALLEY AND MUCH OF SOUTHWEST ARIZONA BEFORE STORMS REDEVELOP
BY EARLY TO MID AFTERNOON. HAVE MADE SOME MINOR FORECAST ADJUSTMENTS
FOR TONIGHT...LOWERING POPS TO ONLY 10 PERCENT WEST OF PHOENIX.

&&

.PREVIOUS DISCUSSION...
THE UPPER LOW WILL DRIFT TO A FAVORABLE POSITION THURSDAY
MORNING. VORTICITY FORCED ASCENT WILL INCREASE AHEAD OF THE LOW AND
SHOWERS ARE EXPECTED TO DEVELOP ACROSS SE AZ AND SW AZ THURSDAY
MORNING. LAPSE RATES WILL STEEPEN DURING THE AFTERNOON AS THE
MID-LEVEL COLD POOL (500 MB TEMPERATURES AS LOW AS -11C) TRANSLATES
EASTWARD. ADDITIONAL ASCENT ASSOCIATED WITH THE RIGHT REAR QUADRANT
OF AN ANOMALOUSLY STRONG JET STREAK WILL SUPPORT ADDITIONAL
CONVECTION ACROSS CENTRAL AZ...MAINLY DURING THE AFTERNOON AND EARLY
EVENING. SOME STORMS WILL AGAIN HAVE THE POTENTIAL TO PRODUCE HEAVY
RAIN...GUSTY WINDS...SMALL HAIL AND LOCALIZED FLOODING. BULK SHEAR
MAGNITUDES ALSO SUGGEST THE POTENTIAL FOR ORGANIZED STORMS CAPABLE
OF PRODUCING SEVERE STORMS...MAINLY FROM PHOENIX EASTWARD.

FRIDAY...
ON FRIDAY THE LOW TRACKS ACROSS ARIZONA AND WEAKENS IN THE PROCESS
WITH DRIER AIR MOVING IN BEHIND IT. THUS POPS TREND DOWNWARD FRIDAY.
TEMPERATURES WILL BE NEAR OR SOMEWHAT BELOW NORMAL THROUGH FRIDAY.

SATURDAY THROUGH TUESDAY...
MODELS SHOW AN INCREASE IN MOISTURE BEHIND THE DEPARTING LOW WITH
POSSIBLY SOME TANGENTIAL INFLUENCE FROM WHAT IS NOW T.S. LOWELL. GFS
SHOWS MORE BROAD TROUGHING OVER THE WESTERN STATES THAN DOES THE
ECWMF WHICH HAS THE RIDGE AXIS FURTHER A BIT FURTHER NORTH THROUGH
MONDAY. AS A RESULT...ECWMF HAS MORE MOISTURE AROUND. ON TUESDAY AND
WEDNESDAY...BOTH MODELS BRING A NORTHEAST PACIFIC RIDGE
INLAND...ECMWF IS MORE AMPLIFIED. MEANWHILE...BOTH MODELS CONTINUE
TO DEPICT YET ANOTHER TROPICAL STORM OFF SOUTHERN BAJA AND DEEPER
MOISTURE OVER OUR FORECAST AREA. IT REMAINS TO BE SEEN JUST HOW THE
MOISTURE PLAYS OUT. HELD ON TO LOW GRADE MONSOON SCENARIO...SLIGHT
CHANCE POPS LIMITED TO SOUTH-CENTRAL ARIZONA...WITH SUBTLE WESTWARD
EXPANSION OF POPS FOR WEDNESDAY.

&&

.AVIATION...
SOUTH-CENTRAL ARIZONA INCLUDING KPHX...KIWA...AND KSDL...

LINGERING SHOWER AND THUNDERSTORM ACTIVITY TO THE WEST OF PHOENIX
WILL GRADUALLY PUSH NORTHWARD BY LATE EVENING...BUT SOME OUTFLOWS
WILL KEEP WESTERLY WINDS ACROSS THE PHOENIX AREA FOR A FEW MORE
HOURS BEFORE DOWNSLOPE EASTERLIES TAKE OVER. CIG LEVELS WILL
GRADUALLY LOWER THROUGH NOON THURSDAY TO AROUND 15K FEET. THERE IS
LOW TO MEDIUM CONFIDENCE OF SOME LIGHT SHOWERS OR VIRGA
AFFECTING AREA TERMINALS SOMETIME BETWEEN 12Z-18Z. AFTERNOON AND
EVENING STORM CHANCES ARE EXPECTED TO MAINLY BE FOCUSED ACROSS
SOUTHWEST ARIZONA...BUT CAN/T RULE OUT A FEW STORMS AFFECTING AREA
TERMINALS LATE THURSDAY AFTERNOON AND EARLY EVENING. EVEN THOUGH
CONFIDENCE IN THESE STORMS IS FAIRLY LOW AT THIS POINT...GUSTY
OUTFLOW WINDS AFFECTING TERMINALS WILL BE THE MORE LIKELY THREAT.

SOUTHWEST ARIZONA AND SOUTHEAST CALIFORNIA INCLUDING KIPL AND KBLH...

UPPER LEVEL LOW WILL PUSH THROUGH THE REGION TONIGHT INTO THURSDAY
WITH A PERIOD OF MORNING SHOWERS AND ISOLATED THUNDERSTORMS POSSIBLE
AROUND 12Z. ADDITIONAL STORM DEVELOPMENT IS EXPECTED DURING THE
AFTERNOON ON THURSDAY...MAINLY ACROSS THE LOWER COLORADO RIVER
VALLEY AND SOUTHWEST ARIZONA. FAIRLY CONFIDENT GUSTY OUTFLOW WINDS
WILL AFFECT KBLH SOMETIME MID TO LATE AFTERNOON THURSDAY...WITH A
LOWER POTENTIAL FOR THUNDERSTORM RAINS AFFECTING THE TERMINAL.

AVIATION DISCUSSION NOT UPDATED FOR AMENDED TAFS.

&&

.FIRE WEATHER...
FRIDAY THROUGH TUESDAY...
STORM CHANCES BEGIN TRENDING DOWNWARD FRIDAY THROUGH EARLY NEXT WEEK
AS WESTERLY FLOW ALOFT TAKES HOLD ACROSS THE AREA. SLIGHTLY DRIER
AIR WILL MOVE INTO THE REGION FROM THE WEST WHICH SHOULD RESULT IN
STORMS IN THE MORE CLIMATOLOGICALLY FAVORED AREAS EAST OF PHOENIX.
LOOKS TO BE A LOW-GRADE MONSOON THROUGH EARLY NEXT WEEK. HUMIDITIES
WILL REMAIN SOMEWHAT ELEVATED WITH FAIR TO GOOD OVERNIGHT RECOVERIES
EXPECTED. WINDS WILL FAVOR TYPICAL DIURNAL DIRECTIONS.

&&

.PSR WATCHES/WARNINGS/ADVISORIES...

AZ...NONE.

CA...NONE.

&&

$$

VISIT US ON FACEBOOK...TWITTER...AND AT WEATHER.GOV/PHOENIX

DISCUSSION...KUHLMAN
PREVIOUS DISCUSSION...HIRSCH/AJ
AVIATION...KUHLMAN
FIRE WEATHER...LEINS









000
FXUS65 KPSR 210409
AFDPSR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PHOENIX AZ
909 PM MST WED AUG 20 2014

.SYNOPSIS...
CHANCES OF STORM ACTIVITY INCREASE ON THURSDAY AS AN UPPER LOW
PRESSURE SYSTEM ALONG THE CALIFORNIA COAST MOVES TOWARDS THE DESERT
SOUTHWEST. DRIER AIR SPREADING IN FROM THE WEST WILL REDUCE
THUNDERSTORM ACTIVITY FROM THIS WEEKEND INTO EARLY NEXT WEEK. BELOW
NORMAL TEMPERATURES ARE FORECAST FROM TODAY THROUGH FRIDAY...WARMING
THIS WEEKEND.

&&

.DISCUSSION...
STORM ACTIVITY TODAY HAS BEEN FOCUSED IN A SOMEWHAT FAVORABLE AREA
OF ACCENT TO THE EAST OF A CLOSED LOW CURRENTLY SITUATED NEAR SAN
DIEGO. INITIALLY...STORMS FIRED OVER THE HIGH TERRAIN AREAS OF
SOUTHERN MARICOPA...NORTHERN YUMA...AND LA PAZ COUNTIES WITH THE LA
PAZ STORM ACTIVITY PRODUCING THE MOST ORGANIZED STORMS. EVEN THOUGH
PWATS ARE MUCH LOWER THAN THE PREVIOUS FEW DAYS...SLOW MOVING AND
SOME BACK BUILDING STORMS ALLOWED FOR A FEW AREAS IN LA PAZ COUNTY
TO SEE SOME HEAVY RAINFALL AND MINOR FLASH FLOODING. SHOWERS AND
THUNDERSTORMS CONTINUE TO MOVE NORTHWARD THROUGH CENTRAL LA PAZ AND
NORTHWEST MARICOPA COUNTIES...ON THE NOSE OF STRONG UPPER LEVEL
MOISTURE ADVECTION. MODELS SHOW THIS MOISTURE SURGE QUITE
WELL...MAINLY FOCUSED ABOVE 15K FEET THROUGH 15Z THURSDAY. ONCE THIS
CURRENT ACTIVITY MOVES NORTHWARD OUT OF OUR CWA BY AROUND 06Z...WE
SHOULD HAVE A BREAK IN THE RAIN THROUGH MUCH OF THE OVERNIGHT. MAY
END UP SEEING SOME LIGHT HIGH BASED SHOWERS OR VIRGA DEVELOP
SOMETIME AFTER DAYBREAK THURSDAY ACROSS SOUTHWEST AND SOUTH-CENTRAL
ARIZONA IN RESPONSE TO THE MOISTURE SURGE AND MODERATE ACCENT AHEAD
OF THE UPPER LEVEL LOW. EXTENSIVE MID AND HIGH LEVEL CLOUD BAND WILL
GRADUALLY SHIFT EASTWARD THROUGH ARIZONA DURING THE DAY
THURSDAY...LEAVING QUITE A BIT OF SUNSHINE FOR THE LOWER COLORADO
RIVER VALLEY AND MUCH OF SOUTHWEST ARIZONA BEFORE STORMS REDEVELOP
BY EARLY TO MID AFTERNOON. HAVE MADE SOME MINOR FORECAST ADJUSTMENTS
FOR TONIGHT...LOWERING POPS TO ONLY 10 PERCENT WEST OF PHOENIX.

&&

.PREVIOUS DISCUSSION...
THE UPPER LOW WILL DRIFT TO A FAVORABLE POSITION THURSDAY
MORNING. VORTICITY FORCED ASCENT WILL INCREASE AHEAD OF THE LOW AND
SHOWERS ARE EXPECTED TO DEVELOP ACROSS SE AZ AND SW AZ THURSDAY
MORNING. LAPSE RATES WILL STEEPEN DURING THE AFTERNOON AS THE
MID-LEVEL COLD POOL (500 MB TEMPERATURES AS LOW AS -11C) TRANSLATES
EASTWARD. ADDITIONAL ASCENT ASSOCIATED WITH THE RIGHT REAR QUADRANT
OF AN ANOMALOUSLY STRONG JET STREAK WILL SUPPORT ADDITIONAL
CONVECTION ACROSS CENTRAL AZ...MAINLY DURING THE AFTERNOON AND EARLY
EVENING. SOME STORMS WILL AGAIN HAVE THE POTENTIAL TO PRODUCE HEAVY
RAIN...GUSTY WINDS...SMALL HAIL AND LOCALIZED FLOODING. BULK SHEAR
MAGNITUDES ALSO SUGGEST THE POTENTIAL FOR ORGANIZED STORMS CAPABLE
OF PRODUCING SEVERE STORMS...MAINLY FROM PHOENIX EASTWARD.

FRIDAY...
ON FRIDAY THE LOW TRACKS ACROSS ARIZONA AND WEAKENS IN THE PROCESS
WITH DRIER AIR MOVING IN BEHIND IT. THUS POPS TREND DOWNWARD FRIDAY.
TEMPERATURES WILL BE NEAR OR SOMEWHAT BELOW NORMAL THROUGH FRIDAY.

SATURDAY THROUGH TUESDAY...
MODELS SHOW AN INCREASE IN MOISTURE BEHIND THE DEPARTING LOW WITH
POSSIBLY SOME TANGENTIAL INFLUENCE FROM WHAT IS NOW T.S. LOWELL. GFS
SHOWS MORE BROAD TROUGHING OVER THE WESTERN STATES THAN DOES THE
ECWMF WHICH HAS THE RIDGE AXIS FURTHER A BIT FURTHER NORTH THROUGH
MONDAY. AS A RESULT...ECWMF HAS MORE MOISTURE AROUND. ON TUESDAY AND
WEDNESDAY...BOTH MODELS BRING A NORTHEAST PACIFIC RIDGE
INLAND...ECMWF IS MORE AMPLIFIED. MEANWHILE...BOTH MODELS CONTINUE
TO DEPICT YET ANOTHER TROPICAL STORM OFF SOUTHERN BAJA AND DEEPER
MOISTURE OVER OUR FORECAST AREA. IT REMAINS TO BE SEEN JUST HOW THE
MOISTURE PLAYS OUT. HELD ON TO LOW GRADE MONSOON SCENARIO...SLIGHT
CHANCE POPS LIMITED TO SOUTH-CENTRAL ARIZONA...WITH SUBTLE WESTWARD
EXPANSION OF POPS FOR WEDNESDAY.

&&

.AVIATION...
SOUTH-CENTRAL ARIZONA INCLUDING KPHX...KIWA...AND KSDL...

LINGERING SHOWER AND THUNDERSTORM ACTIVITY TO THE WEST OF PHOENIX
WILL GRADUALLY PUSH NORTHWARD BY LATE EVENING...BUT SOME OUTFLOWS
WILL KEEP WESTERLY WINDS ACROSS THE PHOENIX AREA FOR A FEW MORE
HOURS BEFORE DOWNSLOPE EASTERLIES TAKE OVER. CIG LEVELS WILL
GRADUALLY LOWER THROUGH NOON THURSDAY TO AROUND 15K FEET. THERE IS
LOW TO MEDIUM CONFIDENCE OF SOME LIGHT SHOWERS OR VIRGA
AFFECTING AREA TERMINALS SOMETIME BETWEEN 12Z-18Z. AFTERNOON AND
EVENING STORM CHANCES ARE EXPECTED TO MAINLY BE FOCUSED ACROSS
SOUTHWEST ARIZONA...BUT CAN/T RULE OUT A FEW STORMS AFFECTING AREA
TERMINALS LATE THURSDAY AFTERNOON AND EARLY EVENING. EVEN THOUGH
CONFIDENCE IN THESE STORMS IS FAIRLY LOW AT THIS POINT...GUSTY
OUTFLOW WINDS AFFECTING TERMINALS WILL BE THE MORE LIKELY THREAT.

SOUTHWEST ARIZONA AND SOUTHEAST CALIFORNIA INCLUDING KIPL AND KBLH...

UPPER LEVEL LOW WILL PUSH THROUGH THE REGION TONIGHT INTO THURSDAY
WITH A PERIOD OF MORNING SHOWERS AND ISOLATED THUNDERSTORMS POSSIBLE
AROUND 12Z. ADDITIONAL STORM DEVELOPMENT IS EXPECTED DURING THE
AFTERNOON ON THURSDAY...MAINLY ACROSS THE LOWER COLORADO RIVER
VALLEY AND SOUTHWEST ARIZONA. FAIRLY CONFIDENT GUSTY OUTFLOW WINDS
WILL AFFECT KBLH SOMETIME MID TO LATE AFTERNOON THURSDAY...WITH A
LOWER POTENTIAL FOR THUNDERSTORM RAINS AFFECTING THE TERMINAL.

AVIATION DISCUSSION NOT UPDATED FOR AMENDED TAFS.

&&

.FIRE WEATHER...
FRIDAY THROUGH TUESDAY...
STORM CHANCES BEGIN TRENDING DOWNWARD FRIDAY THROUGH EARLY NEXT WEEK
AS WESTERLY FLOW ALOFT TAKES HOLD ACROSS THE AREA. SLIGHTLY DRIER
AIR WILL MOVE INTO THE REGION FROM THE WEST WHICH SHOULD RESULT IN
STORMS IN THE MORE CLIMATOLOGICALLY FAVORED AREAS EAST OF PHOENIX.
LOOKS TO BE A LOW-GRADE MONSOON THROUGH EARLY NEXT WEEK. HUMIDITIES
WILL REMAIN SOMEWHAT ELEVATED WITH FAIR TO GOOD OVERNIGHT RECOVERIES
EXPECTED. WINDS WILL FAVOR TYPICAL DIURNAL DIRECTIONS.

&&

.PSR WATCHES/WARNINGS/ADVISORIES...

AZ...NONE.

CA...NONE.

&&

$$

VISIT US ON FACEBOOK...TWITTER...AND AT WEATHER.GOV/PHOENIX

DISCUSSION...KUHLMAN
PREVIOUS DISCUSSION...HIRSCH/AJ
AVIATION...KUHLMAN
FIRE WEATHER...LEINS










000
FXUS65 KPSR 210409
AFDPSR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PHOENIX AZ
909 PM MST WED AUG 20 2014

.SYNOPSIS...
CHANCES OF STORM ACTIVITY INCREASE ON THURSDAY AS AN UPPER LOW
PRESSURE SYSTEM ALONG THE CALIFORNIA COAST MOVES TOWARDS THE DESERT
SOUTHWEST. DRIER AIR SPREADING IN FROM THE WEST WILL REDUCE
THUNDERSTORM ACTIVITY FROM THIS WEEKEND INTO EARLY NEXT WEEK. BELOW
NORMAL TEMPERATURES ARE FORECAST FROM TODAY THROUGH FRIDAY...WARMING
THIS WEEKEND.

&&

.DISCUSSION...
STORM ACTIVITY TODAY HAS BEEN FOCUSED IN A SOMEWHAT FAVORABLE AREA
OF ACCENT TO THE EAST OF A CLOSED LOW CURRENTLY SITUATED NEAR SAN
DIEGO. INITIALLY...STORMS FIRED OVER THE HIGH TERRAIN AREAS OF
SOUTHERN MARICOPA...NORTHERN YUMA...AND LA PAZ COUNTIES WITH THE LA
PAZ STORM ACTIVITY PRODUCING THE MOST ORGANIZED STORMS. EVEN THOUGH
PWATS ARE MUCH LOWER THAN THE PREVIOUS FEW DAYS...SLOW MOVING AND
SOME BACK BUILDING STORMS ALLOWED FOR A FEW AREAS IN LA PAZ COUNTY
TO SEE SOME HEAVY RAINFALL AND MINOR FLASH FLOODING. SHOWERS AND
THUNDERSTORMS CONTINUE TO MOVE NORTHWARD THROUGH CENTRAL LA PAZ AND
NORTHWEST MARICOPA COUNTIES...ON THE NOSE OF STRONG UPPER LEVEL
MOISTURE ADVECTION. MODELS SHOW THIS MOISTURE SURGE QUITE
WELL...MAINLY FOCUSED ABOVE 15K FEET THROUGH 15Z THURSDAY. ONCE THIS
CURRENT ACTIVITY MOVES NORTHWARD OUT OF OUR CWA BY AROUND 06Z...WE
SHOULD HAVE A BREAK IN THE RAIN THROUGH MUCH OF THE OVERNIGHT. MAY
END UP SEEING SOME LIGHT HIGH BASED SHOWERS OR VIRGA DEVELOP
SOMETIME AFTER DAYBREAK THURSDAY ACROSS SOUTHWEST AND SOUTH-CENTRAL
ARIZONA IN RESPONSE TO THE MOISTURE SURGE AND MODERATE ACCENT AHEAD
OF THE UPPER LEVEL LOW. EXTENSIVE MID AND HIGH LEVEL CLOUD BAND WILL
GRADUALLY SHIFT EASTWARD THROUGH ARIZONA DURING THE DAY
THURSDAY...LEAVING QUITE A BIT OF SUNSHINE FOR THE LOWER COLORADO
RIVER VALLEY AND MUCH OF SOUTHWEST ARIZONA BEFORE STORMS REDEVELOP
BY EARLY TO MID AFTERNOON. HAVE MADE SOME MINOR FORECAST ADJUSTMENTS
FOR TONIGHT...LOWERING POPS TO ONLY 10 PERCENT WEST OF PHOENIX.

&&

.PREVIOUS DISCUSSION...
THE UPPER LOW WILL DRIFT TO A FAVORABLE POSITION THURSDAY
MORNING. VORTICITY FORCED ASCENT WILL INCREASE AHEAD OF THE LOW AND
SHOWERS ARE EXPECTED TO DEVELOP ACROSS SE AZ AND SW AZ THURSDAY
MORNING. LAPSE RATES WILL STEEPEN DURING THE AFTERNOON AS THE
MID-LEVEL COLD POOL (500 MB TEMPERATURES AS LOW AS -11C) TRANSLATES
EASTWARD. ADDITIONAL ASCENT ASSOCIATED WITH THE RIGHT REAR QUADRANT
OF AN ANOMALOUSLY STRONG JET STREAK WILL SUPPORT ADDITIONAL
CONVECTION ACROSS CENTRAL AZ...MAINLY DURING THE AFTERNOON AND EARLY
EVENING. SOME STORMS WILL AGAIN HAVE THE POTENTIAL TO PRODUCE HEAVY
RAIN...GUSTY WINDS...SMALL HAIL AND LOCALIZED FLOODING. BULK SHEAR
MAGNITUDES ALSO SUGGEST THE POTENTIAL FOR ORGANIZED STORMS CAPABLE
OF PRODUCING SEVERE STORMS...MAINLY FROM PHOENIX EASTWARD.

FRIDAY...
ON FRIDAY THE LOW TRACKS ACROSS ARIZONA AND WEAKENS IN THE PROCESS
WITH DRIER AIR MOVING IN BEHIND IT. THUS POPS TREND DOWNWARD FRIDAY.
TEMPERATURES WILL BE NEAR OR SOMEWHAT BELOW NORMAL THROUGH FRIDAY.

SATURDAY THROUGH TUESDAY...
MODELS SHOW AN INCREASE IN MOISTURE BEHIND THE DEPARTING LOW WITH
POSSIBLY SOME TANGENTIAL INFLUENCE FROM WHAT IS NOW T.S. LOWELL. GFS
SHOWS MORE BROAD TROUGHING OVER THE WESTERN STATES THAN DOES THE
ECWMF WHICH HAS THE RIDGE AXIS FURTHER A BIT FURTHER NORTH THROUGH
MONDAY. AS A RESULT...ECWMF HAS MORE MOISTURE AROUND. ON TUESDAY AND
WEDNESDAY...BOTH MODELS BRING A NORTHEAST PACIFIC RIDGE
INLAND...ECMWF IS MORE AMPLIFIED. MEANWHILE...BOTH MODELS CONTINUE
TO DEPICT YET ANOTHER TROPICAL STORM OFF SOUTHERN BAJA AND DEEPER
MOISTURE OVER OUR FORECAST AREA. IT REMAINS TO BE SEEN JUST HOW THE
MOISTURE PLAYS OUT. HELD ON TO LOW GRADE MONSOON SCENARIO...SLIGHT
CHANCE POPS LIMITED TO SOUTH-CENTRAL ARIZONA...WITH SUBTLE WESTWARD
EXPANSION OF POPS FOR WEDNESDAY.

&&

.AVIATION...
SOUTH-CENTRAL ARIZONA INCLUDING KPHX...KIWA...AND KSDL...

LINGERING SHOWER AND THUNDERSTORM ACTIVITY TO THE WEST OF PHOENIX
WILL GRADUALLY PUSH NORTHWARD BY LATE EVENING...BUT SOME OUTFLOWS
WILL KEEP WESTERLY WINDS ACROSS THE PHOENIX AREA FOR A FEW MORE
HOURS BEFORE DOWNSLOPE EASTERLIES TAKE OVER. CIG LEVELS WILL
GRADUALLY LOWER THROUGH NOON THURSDAY TO AROUND 15K FEET. THERE IS
LOW TO MEDIUM CONFIDENCE OF SOME LIGHT SHOWERS OR VIRGA
AFFECTING AREA TERMINALS SOMETIME BETWEEN 12Z-18Z. AFTERNOON AND
EVENING STORM CHANCES ARE EXPECTED TO MAINLY BE FOCUSED ACROSS
SOUTHWEST ARIZONA...BUT CAN/T RULE OUT A FEW STORMS AFFECTING AREA
TERMINALS LATE THURSDAY AFTERNOON AND EARLY EVENING. EVEN THOUGH
CONFIDENCE IN THESE STORMS IS FAIRLY LOW AT THIS POINT...GUSTY
OUTFLOW WINDS AFFECTING TERMINALS WILL BE THE MORE LIKELY THREAT.

SOUTHWEST ARIZONA AND SOUTHEAST CALIFORNIA INCLUDING KIPL AND KBLH...

UPPER LEVEL LOW WILL PUSH THROUGH THE REGION TONIGHT INTO THURSDAY
WITH A PERIOD OF MORNING SHOWERS AND ISOLATED THUNDERSTORMS POSSIBLE
AROUND 12Z. ADDITIONAL STORM DEVELOPMENT IS EXPECTED DURING THE
AFTERNOON ON THURSDAY...MAINLY ACROSS THE LOWER COLORADO RIVER
VALLEY AND SOUTHWEST ARIZONA. FAIRLY CONFIDENT GUSTY OUTFLOW WINDS
WILL AFFECT KBLH SOMETIME MID TO LATE AFTERNOON THURSDAY...WITH A
LOWER POTENTIAL FOR THUNDERSTORM RAINS AFFECTING THE TERMINAL.

AVIATION DISCUSSION NOT UPDATED FOR AMENDED TAFS.

&&

.FIRE WEATHER...
FRIDAY THROUGH TUESDAY...
STORM CHANCES BEGIN TRENDING DOWNWARD FRIDAY THROUGH EARLY NEXT WEEK
AS WESTERLY FLOW ALOFT TAKES HOLD ACROSS THE AREA. SLIGHTLY DRIER
AIR WILL MOVE INTO THE REGION FROM THE WEST WHICH SHOULD RESULT IN
STORMS IN THE MORE CLIMATOLOGICALLY FAVORED AREAS EAST OF PHOENIX.
LOOKS TO BE A LOW-GRADE MONSOON THROUGH EARLY NEXT WEEK. HUMIDITIES
WILL REMAIN SOMEWHAT ELEVATED WITH FAIR TO GOOD OVERNIGHT RECOVERIES
EXPECTED. WINDS WILL FAVOR TYPICAL DIURNAL DIRECTIONS.

&&

.PSR WATCHES/WARNINGS/ADVISORIES...

AZ...NONE.

CA...NONE.

&&

$$

VISIT US ON FACEBOOK...TWITTER...AND AT WEATHER.GOV/PHOENIX

DISCUSSION...KUHLMAN
PREVIOUS DISCUSSION...HIRSCH/AJ
AVIATION...KUHLMAN
FIRE WEATHER...LEINS









000
FXUS65 KPSR 202230 AAA
AFDPSR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PHOENIX AZ
329 PM MST WED AUG 20 2014

.UPDATE...UPDATED AVIATION DISCUSSION.

&&

.SYNOPSIS...
CHANCES OF STORM ACTIVITY INCREASE ON THURSDAY AS AN UPPER LOW
PRESSURE SYSTEM ALONG THE CALIFORNIA COAST MOVES TOWARDS THE DESERT
SOUTHWEST. DRIER AIR SPREADING IN FROM THE WEST WILL REDUCE
THUNDERSTORM ACTIVITY FROM THIS WEEKEND INTO EARLY NEXT WEEK. BELOW
NORMAL TEMPERATURES ARE FORECAST FROM TODAY THROUGH FRIDAY...WARMING
THIS WEEKEND.

&&

.DISCUSSION...
UPPER LOW CONTINUES TO DRIFT SOUTHEASTWARD DOWN THE SOUTHERN CA
COAST...RESULTING IN A PROMINENT SOUTHWESTERLY FLOW ACROSS THE
REGION. MEANWHILE...CONDITIONS ARE CONSIDERABLY DRIER THAN THEY WERE
24 HOURS AGO. DEWPOINTS ARE AS LOW AS THE MID 40S ACROSS SE CA AND
LATEST GPS-IPW AT TEMPE WAS MEASURED AT 1.3 INCHES. THIS IS YIELDING
VERY LITTLE CAPE ACROSS THE LOWER DESERTS...WHICH IS ALSO EVIDENT ON
SATELLITE WITH A DEARTH OF TOWERING CU. UPPER LEVEL CONVERGENCE
ASSOCIATED WITH THE RIGHT FRONT QUADRANT OF AN APPROACHING JET
STREAK IS ALSO INHIBITING CONVECTION. CONSEQUENTLY...POPS WERE
LOWERED TO AROUND 10 PERCENT FOR TONIGHT.

AFOREMENTIONED UPPER LOW WILL DRIFT TO A FAVORABLE POSITION THURSDAY
MORNING. VORTICITY FORCED ASCENT WILL INCREASE AHEAD OF THE LOW AND
SHOWERS ARE EXPECTED TO DEVELOP ACROSS SE AZ AND SW AZ THURSDAY
MORNING. LAPSE RATES WILL STEEPEN DURING THE AFTERNOON AS THE
MID-LEVEL COLD POOL (500 MB TEMPERATURES AS LOW AS -11C) TRANSLATES
EASTWARD. ADDITIONAL ASCENT ASSOCIATED WITH THE RIGHT REAR QUADRANT
OF AN ANOMALOUSLY STRONG JET STREAK WILL SUPPORT ADDITIONAL
CONVECTION ACROSS CENTRAL AZ...MAINLY DURING THE AFTERNOON AND EARLY
EVENING. SOME STORMS WILL AGAIN HAVE THE POTENTIAL TO PRODUCE HEAVY
RAIN...GUSTY WINDS...SMALL HAIL AND LOCALIZED FLOODING. BULK SHEAR
MAGNITUDES ALSO SUGGEST THE POTENTIAL FOR ORGANIZED STORMS CAPABLE
OF PRODUCING SEVERE STORMS...MAINLY FROM PHOENIX EASTWARD.

&&

.PREVIOUS DISCUSSION...
FRIDAY...
ON FRIDAY THE LOW TRACKS ACROSS ARIZONA AND WEAKENS IN THE PROCESS
WITH DRIER AIR MOVING IN BEHIND IT. THUS POPS TREND DOWNWARD FRIDAY.
TEMPERATURES WILL BE NEAR OR SOMEWHAT BELOW NORMAL THROUGH FRIDAY.

SATURDAY THROUGH TUESDAY...
MODELS SHOW AN INCREASE IN MOISTURE BEHIND THE DEPARTING LOW WITH
POSSIBLY SOME TANGENTIAL INFLUENCE FROM WHAT IS NOW T.S. LOWELL. GFS
SHOWS MORE BROAD TROUGHING OVER THE WESTERN STATES THAN DOES THE
ECWMF WHICH HAS THE RIDGE AXIS FURTHER A BIT FURTHER NORTH THROUGH
MONDAY. AS A RESULT...ECWMF HAS MORE MOISTURE AROUND. ON TUESDAY AND
WEDNESDAY...BOTH MODELS BRING A NORTHEAST PACIFIC RIDGE
INLAND...ECMWF IS MORE AMPLIFIED. MEANWHILE...BOTH MODELS CONTINUE
TO DEPICT YET ANOTHER TROPICAL STORM OFF SOUTHERN BAJA AND DEEPER
MOISTURE OVER OUR FORECAST AREA. IT REMAINS TO BE SEEN JUST HOW THE
MOISTURE PLAYS OUT. HELD ON TO LOW GRADE MONSOON SCENARIO...SLIGHT
CHANCE POPS LIMITED TO SOUTH-CENTRAL ARIZONA...WITH SUBTLE WESTWARD
EXPANSION OF POPS FOR WEDNESDAY.

&&

.AVIATION...
SOUTH-CENTRAL ARIZONA INCLUDING KPHX...KIWA...AND KSDL...AND
SOUTHWEST ARIZONA AND SOUTHEAST CALIFORNIA INCLUDING KIPL AND KBLH...

THUNDERSTORM ACTIVITY EXPECTED TO REMAIN ISOLATED ACROSS THE REGION
THIS AFTERNOON/EVENING...MAINLY HUGGING THE MOUNTAINS ACROSS EASTERN
AND NORTHERN AZ...BETTER ACTIVITY ACROSS JTNP IN SOUTHEAST CA. NOT
OUT OF THE QUESTION TO SEE A ROGUE STORM MAKE IT INTO THE LOWER AZ
DESERTS THIS EVENING...BUT CONFIDENCE TOO LOW TO INTRODUCE WIND
SHIFTS/OUTFLOW INTO THE TAFS AT THIS TIME. MID-HIGH CLOUDS INCREASE
OVERNIGHT ACROSS THE REGION AS AN UPPER LEVEL DISTURBANCE MOVES
ACROSS SOUTHWEST ARIZONA...WITH ISOLD-WIDELY SCATTERED SHOWERS AND
THUNDERSTORMS BEGINNING TO AFFECT TERMINALS AFTER 13Z THURSDAY.

AVIATION DISCUSSION NOT UPDATED FOR AMENDED TAFS.

&&

.FIRE WEATHER...
FRIDAY THROUGH TUESDAY...
STORM CHANCES BEGIN TRENDING DOWNWARD FRIDAY THROUGH EARLY NEXT WEEK
AS WESTERLY FLOW ALOFT TAKES HOLD ACROSS THE AREA. SLIGHTLY DRIER
AIR WILL MOVE INTO THE REGION FROM THE WEST WHICH SHOULD RESULT IN
STORMS IN THE MORE CLIMATOLOGICALLY FAVORED AREAS EAST OF PHOENIX.
LOOKS TO BE A LOW-GRADE MONSOON THROUGH EARLY NEXT WEEK. HUMIDITIES
WILL REMAIN SOMEWHAT ELEVATED WITH FAIR TO GOOD OVERNIGHT RECOVERIES
EXPECTED. WINDS WILL FAVOR TYPICAL DIURNAL DIRECTIONS.

&&

.PSR WATCHES/WARNINGS/ADVISORIES...

AZ...NONE.

CA...NONE.

&&

$$

VISIT US ON FACEBOOK...TWITTER...AND AT WEATHER.GOV/PHOENIX

DISCUSSION...HIRSCH
PREVIOUS DISCUSSION...AJ
AVIATION...MEYERS
FIRE WEATHER...LEINS






000
FXUS65 KPSR 202230 AAA
AFDPSR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PHOENIX AZ
329 PM MST WED AUG 20 2014

.UPDATE...UPDATED AVIATION DISCUSSION.

&&

.SYNOPSIS...
CHANCES OF STORM ACTIVITY INCREASE ON THURSDAY AS AN UPPER LOW
PRESSURE SYSTEM ALONG THE CALIFORNIA COAST MOVES TOWARDS THE DESERT
SOUTHWEST. DRIER AIR SPREADING IN FROM THE WEST WILL REDUCE
THUNDERSTORM ACTIVITY FROM THIS WEEKEND INTO EARLY NEXT WEEK. BELOW
NORMAL TEMPERATURES ARE FORECAST FROM TODAY THROUGH FRIDAY...WARMING
THIS WEEKEND.

&&

.DISCUSSION...
UPPER LOW CONTINUES TO DRIFT SOUTHEASTWARD DOWN THE SOUTHERN CA
COAST...RESULTING IN A PROMINENT SOUTHWESTERLY FLOW ACROSS THE
REGION. MEANWHILE...CONDITIONS ARE CONSIDERABLY DRIER THAN THEY WERE
24 HOURS AGO. DEWPOINTS ARE AS LOW AS THE MID 40S ACROSS SE CA AND
LATEST GPS-IPW AT TEMPE WAS MEASURED AT 1.3 INCHES. THIS IS YIELDING
VERY LITTLE CAPE ACROSS THE LOWER DESERTS...WHICH IS ALSO EVIDENT ON
SATELLITE WITH A DEARTH OF TOWERING CU. UPPER LEVEL CONVERGENCE
ASSOCIATED WITH THE RIGHT FRONT QUADRANT OF AN APPROACHING JET
STREAK IS ALSO INHIBITING CONVECTION. CONSEQUENTLY...POPS WERE
LOWERED TO AROUND 10 PERCENT FOR TONIGHT.

AFOREMENTIONED UPPER LOW WILL DRIFT TO A FAVORABLE POSITION THURSDAY
MORNING. VORTICITY FORCED ASCENT WILL INCREASE AHEAD OF THE LOW AND
SHOWERS ARE EXPECTED TO DEVELOP ACROSS SE AZ AND SW AZ THURSDAY
MORNING. LAPSE RATES WILL STEEPEN DURING THE AFTERNOON AS THE
MID-LEVEL COLD POOL (500 MB TEMPERATURES AS LOW AS -11C) TRANSLATES
EASTWARD. ADDITIONAL ASCENT ASSOCIATED WITH THE RIGHT REAR QUADRANT
OF AN ANOMALOUSLY STRONG JET STREAK WILL SUPPORT ADDITIONAL
CONVECTION ACROSS CENTRAL AZ...MAINLY DURING THE AFTERNOON AND EARLY
EVENING. SOME STORMS WILL AGAIN HAVE THE POTENTIAL TO PRODUCE HEAVY
RAIN...GUSTY WINDS...SMALL HAIL AND LOCALIZED FLOODING. BULK SHEAR
MAGNITUDES ALSO SUGGEST THE POTENTIAL FOR ORGANIZED STORMS CAPABLE
OF PRODUCING SEVERE STORMS...MAINLY FROM PHOENIX EASTWARD.

&&

.PREVIOUS DISCUSSION...
FRIDAY...
ON FRIDAY THE LOW TRACKS ACROSS ARIZONA AND WEAKENS IN THE PROCESS
WITH DRIER AIR MOVING IN BEHIND IT. THUS POPS TREND DOWNWARD FRIDAY.
TEMPERATURES WILL BE NEAR OR SOMEWHAT BELOW NORMAL THROUGH FRIDAY.

SATURDAY THROUGH TUESDAY...
MODELS SHOW AN INCREASE IN MOISTURE BEHIND THE DEPARTING LOW WITH
POSSIBLY SOME TANGENTIAL INFLUENCE FROM WHAT IS NOW T.S. LOWELL. GFS
SHOWS MORE BROAD TROUGHING OVER THE WESTERN STATES THAN DOES THE
ECWMF WHICH HAS THE RIDGE AXIS FURTHER A BIT FURTHER NORTH THROUGH
MONDAY. AS A RESULT...ECWMF HAS MORE MOISTURE AROUND. ON TUESDAY AND
WEDNESDAY...BOTH MODELS BRING A NORTHEAST PACIFIC RIDGE
INLAND...ECMWF IS MORE AMPLIFIED. MEANWHILE...BOTH MODELS CONTINUE
TO DEPICT YET ANOTHER TROPICAL STORM OFF SOUTHERN BAJA AND DEEPER
MOISTURE OVER OUR FORECAST AREA. IT REMAINS TO BE SEEN JUST HOW THE
MOISTURE PLAYS OUT. HELD ON TO LOW GRADE MONSOON SCENARIO...SLIGHT
CHANCE POPS LIMITED TO SOUTH-CENTRAL ARIZONA...WITH SUBTLE WESTWARD
EXPANSION OF POPS FOR WEDNESDAY.

&&

.AVIATION...
SOUTH-CENTRAL ARIZONA INCLUDING KPHX...KIWA...AND KSDL...AND
SOUTHWEST ARIZONA AND SOUTHEAST CALIFORNIA INCLUDING KIPL AND KBLH...

THUNDERSTORM ACTIVITY EXPECTED TO REMAIN ISOLATED ACROSS THE REGION
THIS AFTERNOON/EVENING...MAINLY HUGGING THE MOUNTAINS ACROSS EASTERN
AND NORTHERN AZ...BETTER ACTIVITY ACROSS JTNP IN SOUTHEAST CA. NOT
OUT OF THE QUESTION TO SEE A ROGUE STORM MAKE IT INTO THE LOWER AZ
DESERTS THIS EVENING...BUT CONFIDENCE TOO LOW TO INTRODUCE WIND
SHIFTS/OUTFLOW INTO THE TAFS AT THIS TIME. MID-HIGH CLOUDS INCREASE
OVERNIGHT ACROSS THE REGION AS AN UPPER LEVEL DISTURBANCE MOVES
ACROSS SOUTHWEST ARIZONA...WITH ISOLD-WIDELY SCATTERED SHOWERS AND
THUNDERSTORMS BEGINNING TO AFFECT TERMINALS AFTER 13Z THURSDAY.

AVIATION DISCUSSION NOT UPDATED FOR AMENDED TAFS.

&&

.FIRE WEATHER...
FRIDAY THROUGH TUESDAY...
STORM CHANCES BEGIN TRENDING DOWNWARD FRIDAY THROUGH EARLY NEXT WEEK
AS WESTERLY FLOW ALOFT TAKES HOLD ACROSS THE AREA. SLIGHTLY DRIER
AIR WILL MOVE INTO THE REGION FROM THE WEST WHICH SHOULD RESULT IN
STORMS IN THE MORE CLIMATOLOGICALLY FAVORED AREAS EAST OF PHOENIX.
LOOKS TO BE A LOW-GRADE MONSOON THROUGH EARLY NEXT WEEK. HUMIDITIES
WILL REMAIN SOMEWHAT ELEVATED WITH FAIR TO GOOD OVERNIGHT RECOVERIES
EXPECTED. WINDS WILL FAVOR TYPICAL DIURNAL DIRECTIONS.

&&

.PSR WATCHES/WARNINGS/ADVISORIES...

AZ...NONE.

CA...NONE.

&&

$$

VISIT US ON FACEBOOK...TWITTER...AND AT WEATHER.GOV/PHOENIX

DISCUSSION...HIRSCH
PREVIOUS DISCUSSION...AJ
AVIATION...MEYERS
FIRE WEATHER...LEINS







000
FXUS65 KPSR 202218
AFDPSR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PHOENIX AZ
320 PM MST WED AUG 20 2014

.SYNOPSIS...
CHANCES OF STORM ACTIVITY INCREASE ON THURSDAY AS AN UPPER LOW
PRESSURE SYSTEM ALONG THE CALIFORNIA COAST MOVES TOWARDS THE DESERT
SOUTHWEST. DRIER AIR SPREADING IN FROM THE WEST WILL REDUCE
THUNDERSTORM ACTIVITY FROM THIS WEEKEND INTO EARLY NEXT WEEK. BELOW
NORMAL TEMPERATURES ARE FORECAST FROM TODAY THROUGH FRIDAY...WARMING
THIS WEEKEND.

&&

.DISCUSSION...
UPPER LOW CONTINUES TO DRIFT SOUTHEASTWARD DOWN THE SOUTHERN CA
COAST...RESULTING IN A PROMINENT SOUTHWESTERLY FLOW ACROSS THE
REGION. MEANWHILE...CONDITIONS ARE CONSIDERABLY DRIER THAN THEY WERE
24 HOURS AGO. DEWPOINTS ARE AS LOW AS THE MID 40S ACROSS SE CA AND
LATEST GPS-IPW AT TEMPE WAS MEASURED AT 1.3 INCHES. THIS IS YIELDING
VERY LITTLE CAPE ACROSS THE LOWER DESERTS...WHICH IS ALSO EVIDENT ON
SATELLITE WITH A DEARTH OF TOWERING CU. UPPER LEVEL CONVERGENCE
ASSOCIATED WITH THE RIGHT FRONT QUADRANT OF AN APPROACHING JET
STREAK IS ALSO INHIBITING CONVECTION. CONSEQUENTLY...POPS WERE
LOWERED TO AROUND 10 PERCENT FOR TONIGHT.

AFOREMENTIONED UPPER LOW WILL DRIFT TO A FAVORABLE POSITION THURSDAY
MORNING. VORTICITY FORCED ASCENT WILL INCREASE AHEAD OF THE LOW AND
SHOWERS ARE EXPECTED TO DEVELOP ACROSS SE AZ AND SW AZ THURSDAY
MORNING. LAPSE RATES WILL STEEPEN DURING THE AFTERNOON AS THE
MID-LEVEL COLD POOL (500 MB TEMPERATURES AS LOW AS -11C) TRANSLATES
EASTWARD. ADDITIONAL ASCENT ASSOCIATED WITH THE RIGHT REAR QUADRANT
OF AN ANOMALOUSLY STRONG JET STREAK WILL SUPPORT ADDITIONAL
CONVECTION ACROSS CENTRAL AZ...MAINLY DURING THE AFTERNOON AND EARLY
EVENING. SOME STORMS WILL AGAIN HAVE THE POTENTIAL TO PRODUCE HEAVY
RAIN...GUSTY WINDS...SMALL HAIL AND LOCALIZED FLOODING. BULK SHEAR
MAGNITUDES ALSO SUGGEST THE POTENTIAL FOR ORGANIZED STORMS CAPABLE
OF PRODUCING SEVERE STORMS...MAINLY FROM PHOENIX EASTWARD.

&&

.PREVIOUS DISCUSSION...
FRIDAY...
ON FRIDAY THE LOW TRACKS ACROSS ARIZONA AND WEAKENS IN THE PROCESS
WITH DRIER AIR MOVING IN BEHIND IT. THUS POPS TREND DOWNWARD FRIDAY.
TEMPERATURES WILL BE NEAR OR SOMEWHAT BELOW NORMAL THROUGH FRIDAY.

SATURDAY THROUGH TUESDAY...
MODELS SHOW AN INCREASE IN MOISTURE BEHIND THE DEPARTING LOW WITH
POSSIBLY SOME TANGENTIAL INFLUENCE FROM WHAT IS NOW T.S. LOWELL. GFS
SHOWS MORE BROAD TROUGHING OVER THE WESTERN STATES THAN DOES THE
ECWMF WHICH HAS THE RIDGE AXIS FURTHER A BIT FURTHER NORTH THROUGH
MONDAY. AS A RESULT...ECWMF HAS MORE MOISTURE AROUND. ON TUESDAY AND
WEDNESDAY...BOTH MODELS BRING A NORTHEAST PACIFIC RIDGE
INLAND...ECMWF IS MORE AMPLIFIED. MEANWHILE...BOTH MODELS CONTINUE
TO DEPICT YET ANOTHER TROPICAL STORM OFF SOUTHERN BAJA AND DEEPER
MOISTURE OVER OUR FORECAST AREA. IT REMAINS TO BE SEEN JUST HOW THE
MOISTURE PLAYS OUT. HELD ON TO LOW GRADE MONSOON SCENARIO...SLIGHT
CHANCE POPS LIMITED TO SOUTH-CENTRAL ARIZONA...WITH SUBTLE WESTWARD
EXPANSION OF POPS FOR WEDNESDAY.

&&

.AVIATION...
SOUTH-CENTRAL ARIZONA INCLUDING KPHX...KIWA...AND KSDL...
COMPARED TO TUESDAY...IT SHOULD BE MUCH LESS ACTIVE ACROSS THE
REGION TODAY WITH ONLY SOME ISOLATED STORMS TO CONTEND WITH MAINLY
EAST OF THE TERMINALS. CONFIDENCE TOO LOW TO INTRODUCE INTO THE
TAFS...BUT SOME OF THE STORMS COULD PUT OUT OUTFLOWS WHICH WOULD
RESULT IN AN EARLIER THAN USUAL EASTERLY WIND SHIFT. OTHERWISE WINDS
WILL FOLLOW TYPICAL DIURNAL PATTERNS.

SOUTHWEST ARIZONA AND SOUTHEAST CALIFORNIA INCLUDING KIPL AND KBLH...
ISOLATED STORMS BEGINNING TO CREEP OVER THE COASTAL MOUNTAINS THIS
MORNING BUT THE HEAVIEST PRECIP SHOULD REMAIN WEST OF THE TERMINALS.
BLH STANDS THE BEST SHOT AT SEEING A SHOWER/STORM AND I INTRODUCED A
FEW HOURS OF VCSH THROUGH LATE MORNING. LOOKS TO BE TOO DRY AT IPL
FOR ANY STORMS TODAY. STORMS SHOULD DISSIPATE AND RE-POSITION
THEMSELVES OVER EASTERN ARIZONA BY THIS AFTERNOON AND BOTH TERMINALS
SHOULD SEE IMPROVING CONDITIONS THIS AFTERNOON/EVENING.

AVIATION DISCUSSION NOT UPDATED FOR AMENDED TAFS.

&&

.FIRE WEATHER...
FRIDAY THROUGH TUESDAY...
STORM CHANCES BEGIN TRENDING DOWNWARD FRIDAY THROUGH EARLY NEXT WEEK
AS WESTERLY FLOW ALOFT TAKES HOLD ACROSS THE AREA. SLIGHTLY DRIER
AIR WILL MOVE INTO THE REGION FROM THE WEST WHICH SHOULD RESULT IN
STORMS IN THE MORE CLIMATOLOGICALLY FAVORED AREAS EAST OF PHOENIX.
LOOKS TO BE A LOW-GRADE MONSOON THROUGH EARLY NEXT WEEK. HUMIDITIES
WILL REMAIN SOMEWHAT ELEVATED WITH FAIR TO GOOD OVERNIGHT RECOVERIES
EXPECTED. WINDS WILL FAVOR TYPICAL DIURNAL DIRECTIONS.

&&

.PSR WATCHES/WARNINGS/ADVISORIES...

AZ...NONE.

CA...NONE.

&&

$$

VISIT US ON FACEBOOK...TWITTER...AND AT WEATHER.GOV/PHOENIX

DISCUSSION...HIRSCH
PREVIOUS DISCUSSION...AJ
AVIATION...LEINS
FIRE WEATHER...LEINS






000
FXUS65 KPSR 202218
AFDPSR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PHOENIX AZ
320 PM MST WED AUG 20 2014

.SYNOPSIS...
CHANCES OF STORM ACTIVITY INCREASE ON THURSDAY AS AN UPPER LOW
PRESSURE SYSTEM ALONG THE CALIFORNIA COAST MOVES TOWARDS THE DESERT
SOUTHWEST. DRIER AIR SPREADING IN FROM THE WEST WILL REDUCE
THUNDERSTORM ACTIVITY FROM THIS WEEKEND INTO EARLY NEXT WEEK. BELOW
NORMAL TEMPERATURES ARE FORECAST FROM TODAY THROUGH FRIDAY...WARMING
THIS WEEKEND.

&&

.DISCUSSION...
UPPER LOW CONTINUES TO DRIFT SOUTHEASTWARD DOWN THE SOUTHERN CA
COAST...RESULTING IN A PROMINENT SOUTHWESTERLY FLOW ACROSS THE
REGION. MEANWHILE...CONDITIONS ARE CONSIDERABLY DRIER THAN THEY WERE
24 HOURS AGO. DEWPOINTS ARE AS LOW AS THE MID 40S ACROSS SE CA AND
LATEST GPS-IPW AT TEMPE WAS MEASURED AT 1.3 INCHES. THIS IS YIELDING
VERY LITTLE CAPE ACROSS THE LOWER DESERTS...WHICH IS ALSO EVIDENT ON
SATELLITE WITH A DEARTH OF TOWERING CU. UPPER LEVEL CONVERGENCE
ASSOCIATED WITH THE RIGHT FRONT QUADRANT OF AN APPROACHING JET
STREAK IS ALSO INHIBITING CONVECTION. CONSEQUENTLY...POPS WERE
LOWERED TO AROUND 10 PERCENT FOR TONIGHT.

AFOREMENTIONED UPPER LOW WILL DRIFT TO A FAVORABLE POSITION THURSDAY
MORNING. VORTICITY FORCED ASCENT WILL INCREASE AHEAD OF THE LOW AND
SHOWERS ARE EXPECTED TO DEVELOP ACROSS SE AZ AND SW AZ THURSDAY
MORNING. LAPSE RATES WILL STEEPEN DURING THE AFTERNOON AS THE
MID-LEVEL COLD POOL (500 MB TEMPERATURES AS LOW AS -11C) TRANSLATES
EASTWARD. ADDITIONAL ASCENT ASSOCIATED WITH THE RIGHT REAR QUADRANT
OF AN ANOMALOUSLY STRONG JET STREAK WILL SUPPORT ADDITIONAL
CONVECTION ACROSS CENTRAL AZ...MAINLY DURING THE AFTERNOON AND EARLY
EVENING. SOME STORMS WILL AGAIN HAVE THE POTENTIAL TO PRODUCE HEAVY
RAIN...GUSTY WINDS...SMALL HAIL AND LOCALIZED FLOODING. BULK SHEAR
MAGNITUDES ALSO SUGGEST THE POTENTIAL FOR ORGANIZED STORMS CAPABLE
OF PRODUCING SEVERE STORMS...MAINLY FROM PHOENIX EASTWARD.

&&

.PREVIOUS DISCUSSION...
FRIDAY...
ON FRIDAY THE LOW TRACKS ACROSS ARIZONA AND WEAKENS IN THE PROCESS
WITH DRIER AIR MOVING IN BEHIND IT. THUS POPS TREND DOWNWARD FRIDAY.
TEMPERATURES WILL BE NEAR OR SOMEWHAT BELOW NORMAL THROUGH FRIDAY.

SATURDAY THROUGH TUESDAY...
MODELS SHOW AN INCREASE IN MOISTURE BEHIND THE DEPARTING LOW WITH
POSSIBLY SOME TANGENTIAL INFLUENCE FROM WHAT IS NOW T.S. LOWELL. GFS
SHOWS MORE BROAD TROUGHING OVER THE WESTERN STATES THAN DOES THE
ECWMF WHICH HAS THE RIDGE AXIS FURTHER A BIT FURTHER NORTH THROUGH
MONDAY. AS A RESULT...ECWMF HAS MORE MOISTURE AROUND. ON TUESDAY AND
WEDNESDAY...BOTH MODELS BRING A NORTHEAST PACIFIC RIDGE
INLAND...ECMWF IS MORE AMPLIFIED. MEANWHILE...BOTH MODELS CONTINUE
TO DEPICT YET ANOTHER TROPICAL STORM OFF SOUTHERN BAJA AND DEEPER
MOISTURE OVER OUR FORECAST AREA. IT REMAINS TO BE SEEN JUST HOW THE
MOISTURE PLAYS OUT. HELD ON TO LOW GRADE MONSOON SCENARIO...SLIGHT
CHANCE POPS LIMITED TO SOUTH-CENTRAL ARIZONA...WITH SUBTLE WESTWARD
EXPANSION OF POPS FOR WEDNESDAY.

&&

.AVIATION...
SOUTH-CENTRAL ARIZONA INCLUDING KPHX...KIWA...AND KSDL...
COMPARED TO TUESDAY...IT SHOULD BE MUCH LESS ACTIVE ACROSS THE
REGION TODAY WITH ONLY SOME ISOLATED STORMS TO CONTEND WITH MAINLY
EAST OF THE TERMINALS. CONFIDENCE TOO LOW TO INTRODUCE INTO THE
TAFS...BUT SOME OF THE STORMS COULD PUT OUT OUTFLOWS WHICH WOULD
RESULT IN AN EARLIER THAN USUAL EASTERLY WIND SHIFT. OTHERWISE WINDS
WILL FOLLOW TYPICAL DIURNAL PATTERNS.

SOUTHWEST ARIZONA AND SOUTHEAST CALIFORNIA INCLUDING KIPL AND KBLH...
ISOLATED STORMS BEGINNING TO CREEP OVER THE COASTAL MOUNTAINS THIS
MORNING BUT THE HEAVIEST PRECIP SHOULD REMAIN WEST OF THE TERMINALS.
BLH STANDS THE BEST SHOT AT SEEING A SHOWER/STORM AND I INTRODUCED A
FEW HOURS OF VCSH THROUGH LATE MORNING. LOOKS TO BE TOO DRY AT IPL
FOR ANY STORMS TODAY. STORMS SHOULD DISSIPATE AND RE-POSITION
THEMSELVES OVER EASTERN ARIZONA BY THIS AFTERNOON AND BOTH TERMINALS
SHOULD SEE IMPROVING CONDITIONS THIS AFTERNOON/EVENING.

AVIATION DISCUSSION NOT UPDATED FOR AMENDED TAFS.

&&

.FIRE WEATHER...
FRIDAY THROUGH TUESDAY...
STORM CHANCES BEGIN TRENDING DOWNWARD FRIDAY THROUGH EARLY NEXT WEEK
AS WESTERLY FLOW ALOFT TAKES HOLD ACROSS THE AREA. SLIGHTLY DRIER
AIR WILL MOVE INTO THE REGION FROM THE WEST WHICH SHOULD RESULT IN
STORMS IN THE MORE CLIMATOLOGICALLY FAVORED AREAS EAST OF PHOENIX.
LOOKS TO BE A LOW-GRADE MONSOON THROUGH EARLY NEXT WEEK. HUMIDITIES
WILL REMAIN SOMEWHAT ELEVATED WITH FAIR TO GOOD OVERNIGHT RECOVERIES
EXPECTED. WINDS WILL FAVOR TYPICAL DIURNAL DIRECTIONS.

&&

.PSR WATCHES/WARNINGS/ADVISORIES...

AZ...NONE.

CA...NONE.

&&

$$

VISIT US ON FACEBOOK...TWITTER...AND AT WEATHER.GOV/PHOENIX

DISCUSSION...HIRSCH
PREVIOUS DISCUSSION...AJ
AVIATION...LEINS
FIRE WEATHER...LEINS







000
FXUS65 KPSR 201619
AFDPSR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PHOENIX AZ
920 AM MST WED AUG 20 2014

.SYNOPSIS...
THERE WILL BE A SLIGHT CHANCE OF SHOWERS AND THUNDERSTORMS TODAY.
CHANCES OF STORM ACTIVITY INCREASE ON THURSDAY AS AN UPPER LOW
PRESSURE SYSTEM ALONG THE CALIFORNIA COAST MOVES TOWARDS THE DESERT
SOUTHWEST. DRIER AIR SPREADING IN FROM THE WEST WILL REDUCE
THUNDERSTORM ACTIVITY FROM THIS WEEKEND INTO EARLY NEXT WEEK. BELOW
NORMAL TEMPERATURES ARE FORECAST FROM TODAY THROUGH FRIDAY...WARMING
THIS WEEKEND.

&&

.DISCUSSION...
UPPER LOW CONTINUES TO DRIFT SOUTHEASTWARD DOWN THE SOUTHERN CA
COAST WITH A LINE OF SHOWERS AND THUNDERSTORMS AHEAD OF THE VORT
MAX. ISOLATED SHOWERS HAVE MADE THEIR WAY INTO JTNP...THOUGH THE
STRONGEST ACTIVITY GENERALLY REMAINS FURTHER WEST ACROSS WESTERN
RIVERSIDE COUNTY. FURTHER EAST ACROSS AZ...CONDITIONS ARE
CONSIDERABLY DRIER THAN THEY WERE 24 HOURS AGO. LATEST GPS-IPW AT
TEMPE WAS MEASURED AT 1.3 INCHES.

UPPER LEVEL CONVERGENCE ASSOCIATED WITH THE FRONT RIGHT QUADRANT OF
AN APPROACHING JET STREAK WILL INHIBIT CONVECTION SOMEWHAT THIS
AFTERNOON. GLOBAL AND CONVECTIVE-ALLOWING MODELS ARE IN GOOD
AGREEMENT THAT SHOWERS AND THUNDERSTORMS WILL GENERALLY BE ISOLATED
IN COVERAGE. THIS IS DEPICTED WELL IN THE CURRENT FORECAST AND ONLY
MINOR SHORT-TERM ADJUSTMENTS ARE NEEDED THIS MORNING.

&&

.PREVIOUS DISCUSSION...
TODAY THROUGH FRIDAY...
AN UPPER LOW CENTERED NEAR CATALINA ISLAND HAS PRODUCED A BAND OF
SHOWERS AND ISOLATED THUNDERSTORMS OVER SOUTHWEST CALIFORNIA EARLY
THIS MORNING AHEAD OF AN APPROACHING VORT LOBE ROTATING AROUND THE
BOTTOM OF THE TROUGH AND WITH IT A STRENGTHENING JET STREAK. THERE
MAY ALSO BE A REMNANT FRONTAL BOUNDARY INVOLVED AS WELL...RAP
ANALYSIS DEPICTS A THERMAL GRADIENT EXTENDING SOUTHWESTWARD FROM THE
L.A.TO SAN DIEGO COAST. INTRODUCED SLIGHT CHANCE POPS FOR THIS
MORNING TO OUR SOUTHEAST CALIFORNIA ZONES IN ACKNOWLEDGMENT OF THIS
FEATURES AS THEY BRUSH OUR WESTERN AREAS. OVERALL THOUGH...MODELS
ARE NOT ENTHUSIASTIC ABOUT STORM ACTIVITY TODAY AS THE COASTAL LOW
SAGS SOUTHWARD AND THE AFOREMENTIONED VORT LOBE MOSTLY MISSES
US...PLUS THE PRECIPITABLE WATER VALUES ARE SIGNIFICANTLY LOWER THAN
YESTERDAY. STILL ENOUGH POTENTIAL TO KEEP SLIGHT CHANCES GOING FOR
TODAY. WITH LESS MOISTURE AVAILABLE AND SOUTHWESTERLY STEERING
FLOW...ANTICIPATE THAT THE STORMS WILL NOT BE NEARLY AS CAPABLE OF
PRODUCING FLOODING BUT BRIEF HEAVY RAIN POTENTIAL IS THERE PLUS
BETTER STRONG WIND POTENTIAL.

THURSDAY IS LOOKING MORE ACTIVE AS THE MODELS AGREE ON THE LOW
SHIFTING FAR ENOUGH EASTWARD TO BRING A VORT LOBE THROUGH OUR AREA.
THEY ALSO INDICATE A SEPARATE PERTURBATION MOVING IN FROM THE
SOUTHWEST AT THE SAME TIME. THIS HAS BEEN THE CASE FOR AT LEAST A
FEW RUNS. JET DYNAMICS COME INTO PLAY AS WELL. THUS...THE BEST
DYNAMICAL FORCING OF THE WEEK LOOKS TO BE THURSDAY. AS A
RESULT...RAISED POPS. WOULD HAVE GONE HIGHER IF PROGGED MOISTURE
AVAILABILITY WAS MORE IMPRESSIVE. VERTICAL WIND SHEAR WILL BE BETTER
ON THURSDAY AS WELL AND THAT WILL AID THE LONGEVITY AND POTENCY OF
ANY STORMS THAT MANAGE TO FORM. MODELS GENERALLY KEEPING THE CAPE
BELOW 1000 J/KG...BELOW 500 PER SREF. ON FRIDAY THE LOW TRACKS
ACROSS ARIZONA AND WEAKENS IN THE PROCESS WITH DRIER AIR MOVING IN
BEHIND IT. THUS POPS TREND DOWNWARD FRIDAY. TEMPERATURES WILL BE
NEAR OR SOMEWHAT BELOW NORMAL THROUGH FRIDAY.

SATURDAY THROUGH TUESDAY...
MODELS SHOW AN INCREASE IN MOISTURE BEHIND THE DEPARTING LOW WITH
POSSIBLY SOME TANGENTIAL INFLUENCE FROM WHAT IS NOW T.S. LOWELL. GFS
SHOWS MORE BROAD TROUGHING OVER THE WESTERN STATES THAN DOES THE
ECWMF WHICH HAS THE RIDGE AXIS FURTHER A BIT FURTHER NORTH THROUGH
MONDAY. AS A RESULT...ECWMF HAS MORE MOISTURE AROUND. ON TUESDAY AND
WEDNESDAY...BOTH MODELS BRING A NORTHEAST PACIFIC RIDGE
INLAND...ECMWF IS MORE AMPLIFIED. MEANWHILE...BOTH MODELS CONTINUE
TO DEPICT YET ANOTHER TROPICAL STORM OFF SOUTHERN BAJA AND DEEPER
MOISTURE OVER OUR FORECAST AREA. IT REMAINS TO BE SEEN JUST HOW THE
MOISTURE PLAYS OUT. HELD ON TO LOW GRADE MONSOON SCENARIO...SLIGHT
CHANCE POPS LIMITED TO SOUTH-CENTRAL ARIZONA...WITH SUBTLE WESTWARD
EXPANSION OF POPS FOR WEDNESDAY.

&&

.AVIATION...
SOUTH-CENTRAL ARIZONA INCLUDING KPHX...KIWA...AND KSDL...
COMPARED TO TUESDAY...IT SHOULD BE MUCH LESS ACTIVE ACROSS THE
REGION TODAY WITH ONLY SOME ISOLATED STORMS TO CONTEND WITH MAINLY
EAST OF THE TERMINALS. CONFIDENCE TOO LOW TO INTRODUCE INTO THE
TAFS...BUT SOME OF THE STORMS COULD PUT OUT OUTFLOWS WHICH WOULD
RESULT IN AN EARLIER THAN USUAL EASTERLY WIND SHIFT. OTHERWISE WINDS
WILL FOLLOW TYPICAL DIURNAL PATTERNS.

SOUTHWEST ARIZONA AND SOUTHEAST CALIFORNIA INCLUDING KIPL AND KBLH...
ISOLATED STORMS BEGINNING TO CREEP OVER THE COASTAL MOUNTAINS THIS
MORNING BUT THE HEAVIEST PRECIP SHOULD REMAIN WEST OF THE TERMINALS.
BLH STANDS THE BEST SHOT AT SEEING A SHOWER/STORM AND I INTRODUCED A
FEW HOURS OF VCSH THROUGH LATE MORNING. LOOKS TO BE TOO DRY AT IPL
FOR ANY STORMS TODAY. STORMS SHOULD DISSIPATE AND RE-POSITION
THEMSELVES OVER EASTERN ARIZONA BY THIS AFTERNOON AND BOTH TERMINALS
SHOULD SEE IMPROVING CONDITIONS THIS AFTERNOON/EVENING.

AVIATION DISCUSSION NOT UPDATED FOR AMENDED TAFS.

&&

.FIRE WEATHER...
FRIDAY THROUGH TUESDAY...
STORM CHANCES BEGIN TRENDING DOWNWARD FRIDAY THROUGH EARLY NEXT WEEK
AS WESTERLY FLOW ALOFT TAKES HOLD ACROSS THE AREA. SLIGHTLY DRIER
AIR WILL MOVE INTO THE REGION FROM THE WEST WHICH SHOULD RESULT IN
STORMS IN THE MORE CLIMATOLOGICALLY FAVORED AREAS EAST OF PHOENIX.
LOOKS TO BE A LOW-GRADE MONSOON THROUGH EARLY NEXT WEEK. HUMIDITIES
WILL REMAIN SOMEWHAT ELEVATED WITH FAIR TO GOOD OVERNIGHT RECOVERIES
EXPECTED. WINDS WILL FAVOR TYPICAL DIURNAL DIRECTIONS.

&&

.PSR WATCHES/WARNINGS/ADVISORIES...

AZ...NONE.

CA...NONE.

&&

$$

VISIT US ON FACEBOOK...TWITTER...AND AT WEATHER.GOV/PHOENIX

DISCUSSION...HIRSCH
PREVIOUS DISCUSSION...AJ
AVIATION...LEINS
FIRE WEATHER...LEINS







000
FXUS65 KPSR 201619
AFDPSR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PHOENIX AZ
920 AM MST WED AUG 20 2014

.SYNOPSIS...
THERE WILL BE A SLIGHT CHANCE OF SHOWERS AND THUNDERSTORMS TODAY.
CHANCES OF STORM ACTIVITY INCREASE ON THURSDAY AS AN UPPER LOW
PRESSURE SYSTEM ALONG THE CALIFORNIA COAST MOVES TOWARDS THE DESERT
SOUTHWEST. DRIER AIR SPREADING IN FROM THE WEST WILL REDUCE
THUNDERSTORM ACTIVITY FROM THIS WEEKEND INTO EARLY NEXT WEEK. BELOW
NORMAL TEMPERATURES ARE FORECAST FROM TODAY THROUGH FRIDAY...WARMING
THIS WEEKEND.

&&

.DISCUSSION...
UPPER LOW CONTINUES TO DRIFT SOUTHEASTWARD DOWN THE SOUTHERN CA
COAST WITH A LINE OF SHOWERS AND THUNDERSTORMS AHEAD OF THE VORT
MAX. ISOLATED SHOWERS HAVE MADE THEIR WAY INTO JTNP...THOUGH THE
STRONGEST ACTIVITY GENERALLY REMAINS FURTHER WEST ACROSS WESTERN
RIVERSIDE COUNTY. FURTHER EAST ACROSS AZ...CONDITIONS ARE
CONSIDERABLY DRIER THAN THEY WERE 24 HOURS AGO. LATEST GPS-IPW AT
TEMPE WAS MEASURED AT 1.3 INCHES.

UPPER LEVEL CONVERGENCE ASSOCIATED WITH THE FRONT RIGHT QUADRANT OF
AN APPROACHING JET STREAK WILL INHIBIT CONVECTION SOMEWHAT THIS
AFTERNOON. GLOBAL AND CONVECTIVE-ALLOWING MODELS ARE IN GOOD
AGREEMENT THAT SHOWERS AND THUNDERSTORMS WILL GENERALLY BE ISOLATED
IN COVERAGE. THIS IS DEPICTED WELL IN THE CURRENT FORECAST AND ONLY
MINOR SHORT-TERM ADJUSTMENTS ARE NEEDED THIS MORNING.

&&

.PREVIOUS DISCUSSION...
TODAY THROUGH FRIDAY...
AN UPPER LOW CENTERED NEAR CATALINA ISLAND HAS PRODUCED A BAND OF
SHOWERS AND ISOLATED THUNDERSTORMS OVER SOUTHWEST CALIFORNIA EARLY
THIS MORNING AHEAD OF AN APPROACHING VORT LOBE ROTATING AROUND THE
BOTTOM OF THE TROUGH AND WITH IT A STRENGTHENING JET STREAK. THERE
MAY ALSO BE A REMNANT FRONTAL BOUNDARY INVOLVED AS WELL...RAP
ANALYSIS DEPICTS A THERMAL GRADIENT EXTENDING SOUTHWESTWARD FROM THE
L.A.TO SAN DIEGO COAST. INTRODUCED SLIGHT CHANCE POPS FOR THIS
MORNING TO OUR SOUTHEAST CALIFORNIA ZONES IN ACKNOWLEDGMENT OF THIS
FEATURES AS THEY BRUSH OUR WESTERN AREAS. OVERALL THOUGH...MODELS
ARE NOT ENTHUSIASTIC ABOUT STORM ACTIVITY TODAY AS THE COASTAL LOW
SAGS SOUTHWARD AND THE AFOREMENTIONED VORT LOBE MOSTLY MISSES
US...PLUS THE PRECIPITABLE WATER VALUES ARE SIGNIFICANTLY LOWER THAN
YESTERDAY. STILL ENOUGH POTENTIAL TO KEEP SLIGHT CHANCES GOING FOR
TODAY. WITH LESS MOISTURE AVAILABLE AND SOUTHWESTERLY STEERING
FLOW...ANTICIPATE THAT THE STORMS WILL NOT BE NEARLY AS CAPABLE OF
PRODUCING FLOODING BUT BRIEF HEAVY RAIN POTENTIAL IS THERE PLUS
BETTER STRONG WIND POTENTIAL.

THURSDAY IS LOOKING MORE ACTIVE AS THE MODELS AGREE ON THE LOW
SHIFTING FAR ENOUGH EASTWARD TO BRING A VORT LOBE THROUGH OUR AREA.
THEY ALSO INDICATE A SEPARATE PERTURBATION MOVING IN FROM THE
SOUTHWEST AT THE SAME TIME. THIS HAS BEEN THE CASE FOR AT LEAST A
FEW RUNS. JET DYNAMICS COME INTO PLAY AS WELL. THUS...THE BEST
DYNAMICAL FORCING OF THE WEEK LOOKS TO BE THURSDAY. AS A
RESULT...RAISED POPS. WOULD HAVE GONE HIGHER IF PROGGED MOISTURE
AVAILABILITY WAS MORE IMPRESSIVE. VERTICAL WIND SHEAR WILL BE BETTER
ON THURSDAY AS WELL AND THAT WILL AID THE LONGEVITY AND POTENCY OF
ANY STORMS THAT MANAGE TO FORM. MODELS GENERALLY KEEPING THE CAPE
BELOW 1000 J/KG...BELOW 500 PER SREF. ON FRIDAY THE LOW TRACKS
ACROSS ARIZONA AND WEAKENS IN THE PROCESS WITH DRIER AIR MOVING IN
BEHIND IT. THUS POPS TREND DOWNWARD FRIDAY. TEMPERATURES WILL BE
NEAR OR SOMEWHAT BELOW NORMAL THROUGH FRIDAY.

SATURDAY THROUGH TUESDAY...
MODELS SHOW AN INCREASE IN MOISTURE BEHIND THE DEPARTING LOW WITH
POSSIBLY SOME TANGENTIAL INFLUENCE FROM WHAT IS NOW T.S. LOWELL. GFS
SHOWS MORE BROAD TROUGHING OVER THE WESTERN STATES THAN DOES THE
ECWMF WHICH HAS THE RIDGE AXIS FURTHER A BIT FURTHER NORTH THROUGH
MONDAY. AS A RESULT...ECWMF HAS MORE MOISTURE AROUND. ON TUESDAY AND
WEDNESDAY...BOTH MODELS BRING A NORTHEAST PACIFIC RIDGE
INLAND...ECMWF IS MORE AMPLIFIED. MEANWHILE...BOTH MODELS CONTINUE
TO DEPICT YET ANOTHER TROPICAL STORM OFF SOUTHERN BAJA AND DEEPER
MOISTURE OVER OUR FORECAST AREA. IT REMAINS TO BE SEEN JUST HOW THE
MOISTURE PLAYS OUT. HELD ON TO LOW GRADE MONSOON SCENARIO...SLIGHT
CHANCE POPS LIMITED TO SOUTH-CENTRAL ARIZONA...WITH SUBTLE WESTWARD
EXPANSION OF POPS FOR WEDNESDAY.

&&

.AVIATION...
SOUTH-CENTRAL ARIZONA INCLUDING KPHX...KIWA...AND KSDL...
COMPARED TO TUESDAY...IT SHOULD BE MUCH LESS ACTIVE ACROSS THE
REGION TODAY WITH ONLY SOME ISOLATED STORMS TO CONTEND WITH MAINLY
EAST OF THE TERMINALS. CONFIDENCE TOO LOW TO INTRODUCE INTO THE
TAFS...BUT SOME OF THE STORMS COULD PUT OUT OUTFLOWS WHICH WOULD
RESULT IN AN EARLIER THAN USUAL EASTERLY WIND SHIFT. OTHERWISE WINDS
WILL FOLLOW TYPICAL DIURNAL PATTERNS.

SOUTHWEST ARIZONA AND SOUTHEAST CALIFORNIA INCLUDING KIPL AND KBLH...
ISOLATED STORMS BEGINNING TO CREEP OVER THE COASTAL MOUNTAINS THIS
MORNING BUT THE HEAVIEST PRECIP SHOULD REMAIN WEST OF THE TERMINALS.
BLH STANDS THE BEST SHOT AT SEEING A SHOWER/STORM AND I INTRODUCED A
FEW HOURS OF VCSH THROUGH LATE MORNING. LOOKS TO BE TOO DRY AT IPL
FOR ANY STORMS TODAY. STORMS SHOULD DISSIPATE AND RE-POSITION
THEMSELVES OVER EASTERN ARIZONA BY THIS AFTERNOON AND BOTH TERMINALS
SHOULD SEE IMPROVING CONDITIONS THIS AFTERNOON/EVENING.

AVIATION DISCUSSION NOT UPDATED FOR AMENDED TAFS.

&&

.FIRE WEATHER...
FRIDAY THROUGH TUESDAY...
STORM CHANCES BEGIN TRENDING DOWNWARD FRIDAY THROUGH EARLY NEXT WEEK
AS WESTERLY FLOW ALOFT TAKES HOLD ACROSS THE AREA. SLIGHTLY DRIER
AIR WILL MOVE INTO THE REGION FROM THE WEST WHICH SHOULD RESULT IN
STORMS IN THE MORE CLIMATOLOGICALLY FAVORED AREAS EAST OF PHOENIX.
LOOKS TO BE A LOW-GRADE MONSOON THROUGH EARLY NEXT WEEK. HUMIDITIES
WILL REMAIN SOMEWHAT ELEVATED WITH FAIR TO GOOD OVERNIGHT RECOVERIES
EXPECTED. WINDS WILL FAVOR TYPICAL DIURNAL DIRECTIONS.

&&

.PSR WATCHES/WARNINGS/ADVISORIES...

AZ...NONE.

CA...NONE.

&&

$$

VISIT US ON FACEBOOK...TWITTER...AND AT WEATHER.GOV/PHOENIX

DISCUSSION...HIRSCH
PREVIOUS DISCUSSION...AJ
AVIATION...LEINS
FIRE WEATHER...LEINS






000
FXUS65 KPSR 201125 AAA
AFDPSR

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE PHOENIX AZ
425 AM MST WED AUG 20 2014

.UPDATE...UPDATED AVIATION AND FIRE WEATHER DISCUSSIONS...

&&

.SYNOPSIS...
THERE WILL BE A SLIGHT CHANCE OF SHOWERS AND THUNDERSTORMS TODAY.
CHANCES OF STORM ACTIVITY INCREASE ON THURSDAY AS AN UPPER LOW
PRESSURE SYSTEM ALONG THE CALIFORNIA COAST MOVES TOWARDS THE DESERT
SOUTHWEST. DRIER AIR SPREADING IN FROM THE WEST WILL REDUCE
THUNDERSTORM ACTIVITY FROM THIS WEEKEND INTO EARLY NEXT WEEK. BELOW
NORMAL TEMPERATURES ARE FORECAST FROM TODAY THROUGH FRIDAY...WARMING
THIS WEEKEND.

&&

.DISCUSSION...
TODAY THROUGH FRIDAY...
AN UPPER LOW CENTERED NEAR CATALINA ISLAND HAS PRODUCED A BAND OF
SHOWERS AND ISOLATED THUNDERSTORMS OVER SOUTHWEST CALIFORNIA EARLY
THIS MORNING AHEAD OF AN APPROACHING VORT LOBE ROTATING AROUND THE
BOTTOM OF THE TROUGH AND WITH IT A STRENGTHENING JET STREAK. THERE
MAY ALSO BE A REMNANT FRONTAL BOUNDARY INVOLVED AS WELL...RAP
ANALYSIS DEPICTS A THERMAL GRADIENT EXTENDING SOUTHWESTWARD FROM THE
L.A.TO SAN DIEGO COAST. INTRODUCED SLIGHT CHANCE POPS FOR THIS
MORNING TO OUR SOUTHEAST CALIFORNIA ZONES IN ACKNOWLEDGMENT OF THIS
FEATURES AS THEY BRUSH OUR WESTERN AREAS. OVERALL THOUGH...MODELS
ARE NOT ENTHUSIASTIC ABOUT STORM ACTIVITY TODAY AS THE COASTAL LOW
SAGS SOUTHWARD AND THE AFOREMENTIONED VORT LOBE MOSTLY MISSES
US...PLUS THE PRECIPITABLE WATER VALUES ARE SIGNIFICANTLY LOWER THAN
YESTERDAY. STILL ENOUGH POTENTIAL TO KEEP SLIGHT CHANCES GOING FOR
TODAY. WITH LESS MOISTURE AVAILABLE AND SOUTHWESTERLY STEERING
FLOW...ANTICIPATE THAT THE STORMS WILL NOT BE NEARLY AS CAPABLE OF
PRODUCING FLOODING BUT BRIEF HEAVY RAIN POTENTIAL IS THERE PLUS
BETTER STRONG WIND POTENTIAL. THURSDAY IS LOOKING MORE ACTIVE AS THE
MODELS AGREE ON THE LOW SHIFTING FAR ENOUGH EASTWARD TO BRING A VORT
LOBE THROUGH OUR AREA. THEY ALSO INDICATE A SEPARATE PERTURBATION
MOVING IN FROM THE SOUTHWEST AT THE SAME TIME. THIS HAS BEEN THE
CASE FOR AT LEAST A FEW RUNS. JET DYNAMICS COME INTO PLAY AS WELL.
THUS...THE BEST DYNAMICAL FORCING OF THE WEEK LOOKS TO BE THURSDAY.
AS A RESULT...RAISED POPS. WOULD HAVE GONE HIGHER IF PROGGED
MOISTURE AVAILABILITY WAS MORE IMPRESSIVE. VERTICAL WIND SHEAR WILL
BE BETTER ON THURSDAY AS WELL AND THAT WILL AID THE LONGEVITY AND
POTENCY OF ANY STORMS THAT MANAGE TO FORM. MODELS GENERALLY KEEPING
THE THE CAPE BELOW 1000 J/KG...BELOW 500 PER SREF. ON FRIDAY THE LOW
TRACKS ACROSS ARIZONA AND WEAKENS IN THE PROCESS WITH DRIER AIR
MOVING IN BEHIND IT. THUS POPS TREND DOWNWARD FRIDAY. TEMPERATURES
WILL BE NEAR OR SOMEWHAT BELOW NORMAL THROUGH FRIDAY.

SATURDAY THROUGH TUESDAY...
MODELS SHOW AN INCREASE IN MOISTURE BEHIND THE DEPARTING LOW WITH
POSSIBLY SOME TANGENTIAL INFLUENCE FROM WHAT IS NOW T.S. LOWELL. GFS
SHOWS MORE BROAD TROUGHING OVER THE WESTERN STATES THAN DOES THE
ECWMF WHICH HAS THE RIDGE AXIS FURTHER A BIT FURTHER NORTH THROUGH
MONDAY. AS A RESULT...ECWMF HAS MORE MOISTURE AROUND. ON TUESDAY AND
WEDNESDAY...BOTH MODELS BRING A NORTHEAST PACIFIC RIDGE
INLAND...ECMWF IS MORE AMPLIFIED. MEANWHILE...BOTH MODELS CONTINUE
TO DEPICT YET ANOTHER TROPICAL STORM OFF SOUTHERN BAJA AND DEEPER
MOISTURE OVER OUR FORECAST AREA. IT REMAINS TO BE SEEN JUST HOW THE
MOISTURE PLAYS OUT. HELD ON TO LOW GRADE MONSOON SCENARIO...SLIGHT
CHANCE POPS LIMITED TO SOUTH-CENTRAL ARIZONA...WITH SUBTLE WESTWARD
EXPANSION OF POPS FOR WEDNESDAY.

&&

.AVIATION...
SOUTH-CENTRAL ARIZONA INCLUDING KPHX...KIWA...AND KSDL...
COMPARED TO TUESDAY...IT SHOULD BE MUCH LESS ACTIVE ACROSS THE
REGION TODAY WITH ONLY SOME ISOLATED STORMS TO CONTEND WITH MAINLY
EAST OF THE TERMINALS. CONFIDENCE TOO LOW TO INTRODUCE INTO THE
TAFS...BUT SOME OF THE STORMS COULD PUT OUT OUTFLOWS WHICH WOULD
RESULT IN AN EARLIER THAN USUAL EASTERLY WIND SHIFT. OTHERWISE WINDS
WILL FOLLOW TYPICAL DIURNAL PATTERNS.

SOUTHWEST ARIZONA AND SOUTHEAST CALIFORNIA INCLUDING KIPL AND KBLH...
ISOLATED STORMS BEGINNING TO CREEP OVER THE COASTAL MOUNTAINS THIS
MORNING BUT THE HEAVIEST PRECIP SHOULD REMAIN WEST OF THE TERMINALS.
BLH STANDS THE BEST SHOT AT SEEING A SHOWER/STORM AND I INTRODUCED A
FEW HOURS OF VCSH THROUGH LATE MORNING. LOOKS TO BE TOO DRY AT IPL
FOR ANY STORMS TODAY. STORMS SHOULD DISSIPATE AND RE-POSITION
THEMSELVES OVER EASTERN ARIZONA BY THIS AFTERNOON AND BOTH TERMINALS
SHOULD SEE IMPROVING CONDITIONS THIS AFTERNOON/EVENING.

AVIATION DISCUSSION NOT UPDATED FOR AMENDED TAFS.

&&

.FIRE WEATHER...
FRIDAY THROUGH TUESDAY...
STORM CHANCES BEGIN TRENDING DOWNWARD FRIDAY THROUGH EARLY NEXT WEEK
AS WESTERLY FLOW ALOFT TAKES HOLD ACROSS THE AREA. SLIGHTLY DRIER
AIR WILL MOVE INTO THE REGION FROM THE WEST WHICH SHOULD RESULT IN
STORMS IN THE MORE CLIMATOLOGICALLY FAVORED AREAS EAST OF PHOENIX.
LOOKS TO BE A LOW-GRADE MONSOON THROUGH EARLY NEXT WEEK. HUMIDITIES
WILL REMAIN SOMEWHAT ELEVATED WITH FAIR TO GOOD OVERNIGHT RECOVERIES
EXPECTED. WINDS WILL FAVOR TYPICAL DIURNAL DIRECTIONS.

&&

.PSR WATCHES/WARNINGS/ADVISORIES...

AZ...NONE.

CA...NONE.

&&

$$

VISIT US ON FACEBOOK...TWITTER...AND AT WEATHER.GOV/PHOENIX

DISCUSSION...AJ
AVIATION...LEINS
FIRE WEATHER...LEINS






000
FXUS65 KPSR 201125 AAA
AFDPSR

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE PHOENIX AZ
425 AM MST WED AUG 20 2014

.UPDATE...UPDATED AVIATION AND FIRE WEATHER DISCUSSIONS...

&&

.SYNOPSIS...
THERE WILL BE A SLIGHT CHANCE OF SHOWERS AND THUNDERSTORMS TODAY.
CHANCES OF STORM ACTIVITY INCREASE ON THURSDAY AS AN UPPER LOW
PRESSURE SYSTEM ALONG THE CALIFORNIA COAST MOVES TOWARDS THE DESERT
SOUTHWEST. DRIER AIR SPREADING IN FROM THE WEST WILL REDUCE
THUNDERSTORM ACTIVITY FROM THIS WEEKEND INTO EARLY NEXT WEEK. BELOW
NORMAL TEMPERATURES ARE FORECAST FROM TODAY THROUGH FRIDAY...WARMING
THIS WEEKEND.

&&

.DISCUSSION...
TODAY THROUGH FRIDAY...
AN UPPER LOW CENTERED NEAR CATALINA ISLAND HAS PRODUCED A BAND OF
SHOWERS AND ISOLATED THUNDERSTORMS OVER SOUTHWEST CALIFORNIA EARLY
THIS MORNING AHEAD OF AN APPROACHING VORT LOBE ROTATING AROUND THE
BOTTOM OF THE TROUGH AND WITH IT A STRENGTHENING JET STREAK. THERE
MAY ALSO BE A REMNANT FRONTAL BOUNDARY INVOLVED AS WELL...RAP
ANALYSIS DEPICTS A THERMAL GRADIENT EXTENDING SOUTHWESTWARD FROM THE
L.A.TO SAN DIEGO COAST. INTRODUCED SLIGHT CHANCE POPS FOR THIS
MORNING TO OUR SOUTHEAST CALIFORNIA ZONES IN ACKNOWLEDGMENT OF THIS
FEATURES AS THEY BRUSH OUR WESTERN AREAS. OVERALL THOUGH...MODELS
ARE NOT ENTHUSIASTIC ABOUT STORM ACTIVITY TODAY AS THE COASTAL LOW
SAGS SOUTHWARD AND THE AFOREMENTIONED VORT LOBE MOSTLY MISSES
US...PLUS THE PRECIPITABLE WATER VALUES ARE SIGNIFICANTLY LOWER THAN
YESTERDAY. STILL ENOUGH POTENTIAL TO KEEP SLIGHT CHANCES GOING FOR
TODAY. WITH LESS MOISTURE AVAILABLE AND SOUTHWESTERLY STEERING
FLOW...ANTICIPATE THAT THE STORMS WILL NOT BE NEARLY AS CAPABLE OF
PRODUCING FLOODING BUT BRIEF HEAVY RAIN POTENTIAL IS THERE PLUS
BETTER STRONG WIND POTENTIAL. THURSDAY IS LOOKING MORE ACTIVE AS THE
MODELS AGREE ON THE LOW SHIFTING FAR ENOUGH EASTWARD TO BRING A VORT
LOBE THROUGH OUR AREA. THEY ALSO INDICATE A SEPARATE PERTURBATION
MOVING IN FROM THE SOUTHWEST AT THE SAME TIME. THIS HAS BEEN THE
CASE FOR AT LEAST A FEW RUNS. JET DYNAMICS COME INTO PLAY AS WELL.
THUS...THE BEST DYNAMICAL FORCING OF THE WEEK LOOKS TO BE THURSDAY.
AS A RESULT...RAISED POPS. WOULD HAVE GONE HIGHER IF PROGGED
MOISTURE AVAILABILITY WAS MORE IMPRESSIVE. VERTICAL WIND SHEAR WILL
BE BETTER ON THURSDAY AS WELL AND THAT WILL AID THE LONGEVITY AND
POTENCY OF ANY STORMS THAT MANAGE TO FORM. MODELS GENERALLY KEEPING
THE THE CAPE BELOW 1000 J/KG...BELOW 500 PER SREF. ON FRIDAY THE LOW
TRACKS ACROSS ARIZONA AND WEAKENS IN THE PROCESS WITH DRIER AIR
MOVING IN BEHIND IT. THUS POPS TREND DOWNWARD FRIDAY. TEMPERATURES
WILL BE NEAR OR SOMEWHAT BELOW NORMAL THROUGH FRIDAY.

SATURDAY THROUGH TUESDAY...
MODELS SHOW AN INCREASE IN MOISTURE BEHIND THE DEPARTING LOW WITH
POSSIBLY SOME TANGENTIAL INFLUENCE FROM WHAT IS NOW T.S. LOWELL. GFS
SHOWS MORE BROAD TROUGHING OVER THE WESTERN STATES THAN DOES THE
ECWMF WHICH HAS THE RIDGE AXIS FURTHER A BIT FURTHER NORTH THROUGH
MONDAY. AS A RESULT...ECWMF HAS MORE MOISTURE AROUND. ON TUESDAY AND
WEDNESDAY...BOTH MODELS BRING A NORTHEAST PACIFIC RIDGE
INLAND...ECMWF IS MORE AMPLIFIED. MEANWHILE...BOTH MODELS CONTINUE
TO DEPICT YET ANOTHER TROPICAL STORM OFF SOUTHERN BAJA AND DEEPER
MOISTURE OVER OUR FORECAST AREA. IT REMAINS TO BE SEEN JUST HOW THE
MOISTURE PLAYS OUT. HELD ON TO LOW GRADE MONSOON SCENARIO...SLIGHT
CHANCE POPS LIMITED TO SOUTH-CENTRAL ARIZONA...WITH SUBTLE WESTWARD
EXPANSION OF POPS FOR WEDNESDAY.

&&

.AVIATION...
SOUTH-CENTRAL ARIZONA INCLUDING KPHX...KIWA...AND KSDL...
COMPARED TO TUESDAY...IT SHOULD BE MUCH LESS ACTIVE ACROSS THE
REGION TODAY WITH ONLY SOME ISOLATED STORMS TO CONTEND WITH MAINLY
EAST OF THE TERMINALS. CONFIDENCE TOO LOW TO INTRODUCE INTO THE
TAFS...BUT SOME OF THE STORMS COULD PUT OUT OUTFLOWS WHICH WOULD
RESULT IN AN EARLIER THAN USUAL EASTERLY WIND SHIFT. OTHERWISE WINDS
WILL FOLLOW TYPICAL DIURNAL PATTERNS.

SOUTHWEST ARIZONA AND SOUTHEAST CALIFORNIA INCLUDING KIPL AND KBLH...
ISOLATED STORMS BEGINNING TO CREEP OVER THE COASTAL MOUNTAINS THIS
MORNING BUT THE HEAVIEST PRECIP SHOULD REMAIN WEST OF THE TERMINALS.
BLH STANDS THE BEST SHOT AT SEEING A SHOWER/STORM AND I INTRODUCED A
FEW HOURS OF VCSH THROUGH LATE MORNING. LOOKS TO BE TOO DRY AT IPL
FOR ANY STORMS TODAY. STORMS SHOULD DISSIPATE AND RE-POSITION
THEMSELVES OVER EASTERN ARIZONA BY THIS AFTERNOON AND BOTH TERMINALS
SHOULD SEE IMPROVING CONDITIONS THIS AFTERNOON/EVENING.

AVIATION DISCUSSION NOT UPDATED FOR AMENDED TAFS.

&&

.FIRE WEATHER...
FRIDAY THROUGH TUESDAY...
STORM CHANCES BEGIN TRENDING DOWNWARD FRIDAY THROUGH EARLY NEXT WEEK
AS WESTERLY FLOW ALOFT TAKES HOLD ACROSS THE AREA. SLIGHTLY DRIER
AIR WILL MOVE INTO THE REGION FROM THE WEST WHICH SHOULD RESULT IN
STORMS IN THE MORE CLIMATOLOGICALLY FAVORED AREAS EAST OF PHOENIX.
LOOKS TO BE A LOW-GRADE MONSOON THROUGH EARLY NEXT WEEK. HUMIDITIES
WILL REMAIN SOMEWHAT ELEVATED WITH FAIR TO GOOD OVERNIGHT RECOVERIES
EXPECTED. WINDS WILL FAVOR TYPICAL DIURNAL DIRECTIONS.

&&

.PSR WATCHES/WARNINGS/ADVISORIES...

AZ...NONE.

CA...NONE.

&&

$$

VISIT US ON FACEBOOK...TWITTER...AND AT WEATHER.GOV/PHOENIX

DISCUSSION...AJ
AVIATION...LEINS
FIRE WEATHER...LEINS







000
FXUS65 KPSR 201105
AFDPSR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PHOENIX AZ
405 AM MST WED AUG 20 2014


.SYNOPSIS...
THERE WILL BE A SLIGHT CHANCE OF SHOWERS AND THUNDERSTORMS TODAY.
CHANCES OF STORM ACTIVITY INCREASE ON THURSDAY AS AN UPPER LOW
PRESSURE SYSTEM ALONG THE CALIFORNIA COAST MOVES TOWARDS THE DESERT
SOUTHWEST. DRIER AIR SPREADING IN FROM THE WEST WILL REDUCE
THUNDERSTORM ACTIVITY FROM THIS WEEKEND INTO EARLY NEXT WEEK. BELOW
NORMAL TEMPERATURES ARE FORECAST FROM TODAY THROUGH FRIDAY...WARMING
THIS WEEKEND.

&&

.DISCUSSION...
TODAY THROUGH FRIDAY...
AN UPPER LOW CENTERED NEAR CATALINA ISLAND HAS PRODUCED A BAND OF
SHOWERS AND ISOLATED THUNDERSTORMS OVER SOUTHWEST CALIFORNIA EARLY
THIS MORNING AHEAD OF AN APPROACHING VORT LOBE ROTATING AROUND THE
BOTTOM OF THE TROUGH AND WITH IT A STRENGTHENING JET STREAK. THERE
MAY ALSO BE A REMNANT FRONTAL BOUNDARY INVOLVED AS WELL...RAP
ANALYSIS DEPICTS A THERMAL GRADIENT EXTENDING SOUTHWESTWARD FROM THE
L.A.TO SAN DIEGO COAST. INTRODUCED SLIGHT CHANCE POPS FOR THIS
MORNING TO OUR SOUTHEAST CALIFORNIA ZONES IN ACKNOWLEDGMENT OF THIS
FEATURES AS THEY BRUSH OUR WESTERN AREAS. OVERALL THOUGH...MODELS
ARE NOT ENTHUSIASTIC ABOUT STORM ACTIVITY TODAY AS THE COASTAL LOW
SAGS SOUTHWARD AND THE AFOREMENTIONED VORT LOBE MOSTLY MISSES
US...PLUS THE PRECIPITABLE WATER VALUES ARE SIGNIFICANTLY LOWER THAN
YESTERDAY. STILL ENOUGH POTENTIAL TO KEEP SLIGHT CHANCES GOING FOR
TODAY. WITH LESS MOISTURE AVAILABLE AND SOUTHWESTERLY STEERING
FLOW...ANTICIPATE THAT THE STORMS WILL NOT BE NEARLY AS CAPABLE OF
PRODUCING FLOODING BUT BRIEF HEAVY RAIN POTENTIAL IS THERE PLUS
BETTER STRONG WIND POTENTIAL. THURSDAY IS LOOKING MORE ACTIVE AS THE
MODELS AGREE ON THE LOW SHIFTING FAR ENOUGH EASTWARD TO BRING A VORT
LOBE THROUGH OUR AREA. THEY ALSO INDICATE A SEPARATE PERTURBATION
MOVING IN FROM THE SOUTHWEST AT THE SAME TIME. THIS HAS BEEN THE
CASE FOR AT LEAST A FEW RUNS. JET DYNAMICS COME INTO PLAY AS WELL.
THUS...THE BEST DYNAMICAL FORCING OF THE WEEK LOOKS TO BE THURSDAY.
AS A RESULT...RAISED POPS. WOULD HAVE GONE HIGHER IF PROGGED
MOISTURE AVAILABILITY WAS MORE IMPRESSIVE. VERTICAL WIND SHEAR WILL
BE BETTER ON THURSDAY AS WELL AND THAT WILL AID THE LONGEVITY AND
POTENCY OF ANY STORMS THAT MANAGE TO FORM. MODELS GENERALLY KEEPING
THE THE CAPE BELOW 1000 J/KG...BELOW 500 PER SREF. ON FRIDAY THE LOW
TRACKS ACROSS ARIZONA AND WEAKENS IN THE PROCESS WITH DRIER AIR
MOVING IN BEHIND IT. THUS POPS TREND DOWNWARD FRIDAY. TEMPERATURES
WILL BE NEAR OR SOMEWHAT BELOW NORMAL THROUGH FRIDAY.

SATURDAY THROUGH TUESDAY...
MODELS SHOW AN INCREASE IN MOISTURE BEHIND THE DEPARTING LOW WITH
POSSIBLY SOME TANGENTIAL INFLUENCE FROM WHAT IS NOW T.S. LOWELL. GFS
SHOWS MORE BROAD TROUGHING OVER THE WESTERN STATES THAN DOES THE
ECWMF WHICH HAS THE RIDGE AXIS FURTHER A BIT FURTHER NORTH THROUGH
MONDAY. AS A RESULT...ECWMF HAS MORE MOISTURE AROUND. ON TUESDAY AND
WEDNESDAY...BOTH MODELS BRING A NORTHEAST PACIFIC RIDGE
INLAND...ECMWF IS MORE AMPLIFIED. MEANWHILE...BOTH MODELS CONTINUE
TO DEPICT YET ANOTHER TROPICAL STORM OFF SOUTHERN BAJA AND DEEPER
MOISTURE OVER OUR FORECAST AREA. IT REMAINS TO BE SEEN JUST HOW THE
MOISTURE PLAYS OUT. HELD ON TO LOW GRADE MONSOON SCENARIO...SLIGHT
CHANCE POPS LIMITED TO SOUTH-CENTRAL ARIZONA...WITH SUBTLE WESTWARD
EXPANSION OF POPS FOR WEDNESDAY.

&&

.AVIATION...
SOUTH-CENTRAL ARIZONA INCLUDING KPHX...KIWA...AND KSDL...

ISOLATED SHOWERS AND THUNDERSTORMS WILL CONTINUE ACROSS THE PHOENIX
VALLEY THROUGH 06Z. SCT CLOUD DECKS BTWN 6 AND 10 THSD FT AGL...
WITH BKN CLOUDS ABOVE 14 THSD THROUGH 10Z. WEST WINDS WILL DIMINISH
FROM 15 KNOTS AT 04Z WED TO LGT AND VRBL BY 07Z WED. FROM 07Z WED TO
18Z MON...LGT VRBL WNDS. SCT CLDS AOA 10 THSD AGL.



SOUTHWEST ARIZONA AND SOUTHEAST CALIFORNIA INCLUDING KIPL AND KBLH...

THROUGH 18Z WED...MOSTLY CLEAR SKIES. LIGHT WEST TO SOUTHWEST WIND
UNDER 9 KNOTS.

AVIATION DISCUSSION NOT UPDATED FOR AMENDED TAFS.

&&

.FIRE WEATHER...
THURSDAY THROUGH MONDAY...
A SLIGHT CHANCE OF AFTERNOON AND EVENING THUNDERSTORMS WILL CONTINUE
MAINLY EAST OF THE LOWER COLORADO RIVER VALLEY ON THURSDAY WITH A
CHANCE ACROSS THE HIGHER TERRAIN EAST OF PHOENIX. LITTLE CHANGE IS
EXPECTED FRIDAY. HIGH TEMPERATURES BOTH DAYS WILL STAY BELOW
SEASONAL NORMALS...WITH COOLER DESERTS FALLING INTO THE 90S.
HUMIDITY LEVELS WILL STAY QUITE ELEVATED WITH MOST OF THE DESERTS
RECORDING MINIMUM RH VALUES BETWEEN 20 AND 30 PERCENT. A STEADY
SOUTHWEST FLOW ALOFT WILL LEAD TO GRADUAL DRYING AND WARMING
CONDITIONS OVER THE WEEKEND AND INTO EARLY NEXT WEEK. BY SUNDAY
THERE WILL BE JUST A SLIGHT CHANCE OF AFTERNOON AND EVENING
THUNDERSTORMS ACROSS THE HIGHER TERRAIN EAST OF PHOENIX WITH PARTLY
TO MOSTLY SUNNY SKIES EXPECTED ELSEWHERE. DESPITE THE DRYING
TREND...MINIMUM RH VALUES WILL STAY ON THE ELEVATED SIDE AND SHOULD
MOSTLY RANGE FROM 15 TO 25 PERCENT. NO STRONG WINDS ARE EXPECTED
THROUGH THE PERIOD...MAINLY NORMAL DIURNAL WINDS FAVORING THE SOUTH
TO SOUTHWEST LESS THAN 15 MPH.

&&

.PSR WATCHES/WARNINGS/ADVISORIES...

AZ...NONE.

CA...NONE.

&&

$$

VISIT US ON FACEBOOK...TWITTER...AND AT WEATHER.GOV/PHOENIX

DISCUSSION...AJ
AVIATION....VASQUEZ
FIRE WEATHER...CB








000
FXUS65 KPSR 201105
AFDPSR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PHOENIX AZ
405 AM MST WED AUG 20 2014


.SYNOPSIS...
THERE WILL BE A SLIGHT CHANCE OF SHOWERS AND THUNDERSTORMS TODAY.
CHANCES OF STORM ACTIVITY INCREASE ON THURSDAY AS AN UPPER LOW
PRESSURE SYSTEM ALONG THE CALIFORNIA COAST MOVES TOWARDS THE DESERT
SOUTHWEST. DRIER AIR SPREADING IN FROM THE WEST WILL REDUCE
THUNDERSTORM ACTIVITY FROM THIS WEEKEND INTO EARLY NEXT WEEK. BELOW
NORMAL TEMPERATURES ARE FORECAST FROM TODAY THROUGH FRIDAY...WARMING
THIS WEEKEND.

&&

.DISCUSSION...
TODAY THROUGH FRIDAY...
AN UPPER LOW CENTERED NEAR CATALINA ISLAND HAS PRODUCED A BAND OF
SHOWERS AND ISOLATED THUNDERSTORMS OVER SOUTHWEST CALIFORNIA EARLY
THIS MORNING AHEAD OF AN APPROACHING VORT LOBE ROTATING AROUND THE
BOTTOM OF THE TROUGH AND WITH IT A STRENGTHENING JET STREAK. THERE
MAY ALSO BE A REMNANT FRONTAL BOUNDARY INVOLVED AS WELL...RAP
ANALYSIS DEPICTS A THERMAL GRADIENT EXTENDING SOUTHWESTWARD FROM THE
L.A.TO SAN DIEGO COAST. INTRODUCED SLIGHT CHANCE POPS FOR THIS
MORNING TO OUR SOUTHEAST CALIFORNIA ZONES IN ACKNOWLEDGMENT OF THIS
FEATURES AS THEY BRUSH OUR WESTERN AREAS. OVERALL THOUGH...MODELS
ARE NOT ENTHUSIASTIC ABOUT STORM ACTIVITY TODAY AS THE COASTAL LOW
SAGS SOUTHWARD AND THE AFOREMENTIONED VORT LOBE MOSTLY MISSES
US...PLUS THE PRECIPITABLE WATER VALUES ARE SIGNIFICANTLY LOWER THAN
YESTERDAY. STILL ENOUGH POTENTIAL TO KEEP SLIGHT CHANCES GOING FOR
TODAY. WITH LESS MOISTURE AVAILABLE AND SOUTHWESTERLY STEERING
FLOW...ANTICIPATE THAT THE STORMS WILL NOT BE NEARLY AS CAPABLE OF
PRODUCING FLOODING BUT BRIEF HEAVY RAIN POTENTIAL IS THERE PLUS
BETTER STRONG WIND POTENTIAL. THURSDAY IS LOOKING MORE ACTIVE AS THE
MODELS AGREE ON THE LOW SHIFTING FAR ENOUGH EASTWARD TO BRING A VORT
LOBE THROUGH OUR AREA. THEY ALSO INDICATE A SEPARATE PERTURBATION
MOVING IN FROM THE SOUTHWEST AT THE SAME TIME. THIS HAS BEEN THE
CASE FOR AT LEAST A FEW RUNS. JET DYNAMICS COME INTO PLAY AS WELL.
THUS...THE BEST DYNAMICAL FORCING OF THE WEEK LOOKS TO BE THURSDAY.
AS A RESULT...RAISED POPS. WOULD HAVE GONE HIGHER IF PROGGED
MOISTURE AVAILABILITY WAS MORE IMPRESSIVE. VERTICAL WIND SHEAR WILL
BE BETTER ON THURSDAY AS WELL AND THAT WILL AID THE LONGEVITY AND
POTENCY OF ANY STORMS THAT MANAGE TO FORM. MODELS GENERALLY KEEPING
THE THE CAPE BELOW 1000 J/KG...BELOW 500 PER SREF. ON FRIDAY THE LOW
TRACKS ACROSS ARIZONA AND WEAKENS IN THE PROCESS WITH DRIER AIR
MOVING IN BEHIND IT. THUS POPS TREND DOWNWARD FRIDAY. TEMPERATURES
WILL BE NEAR OR SOMEWHAT BELOW NORMAL THROUGH FRIDAY.

SATURDAY THROUGH TUESDAY...
MODELS SHOW AN INCREASE IN MOISTURE BEHIND THE DEPARTING LOW WITH
POSSIBLY SOME TANGENTIAL INFLUENCE FROM WHAT IS NOW T.S. LOWELL. GFS
SHOWS MORE BROAD TROUGHING OVER THE WESTERN STATES THAN DOES THE
ECWMF WHICH HAS THE RIDGE AXIS FURTHER A BIT FURTHER NORTH THROUGH
MONDAY. AS A RESULT...ECWMF HAS MORE MOISTURE AROUND. ON TUESDAY AND
WEDNESDAY...BOTH MODELS BRING A NORTHEAST PACIFIC RIDGE
INLAND...ECMWF IS MORE AMPLIFIED. MEANWHILE...BOTH MODELS CONTINUE
TO DEPICT YET ANOTHER TROPICAL STORM OFF SOUTHERN BAJA AND DEEPER
MOISTURE OVER OUR FORECAST AREA. IT REMAINS TO BE SEEN JUST HOW THE
MOISTURE PLAYS OUT. HELD ON TO LOW GRADE MONSOON SCENARIO...SLIGHT
CHANCE POPS LIMITED TO SOUTH-CENTRAL ARIZONA...WITH SUBTLE WESTWARD
EXPANSION OF POPS FOR WEDNESDAY.

&&

.AVIATION...
SOUTH-CENTRAL ARIZONA INCLUDING KPHX...KIWA...AND KSDL...

ISOLATED SHOWERS AND THUNDERSTORMS WILL CONTINUE ACROSS THE PHOENIX
VALLEY THROUGH 06Z. SCT CLOUD DECKS BTWN 6 AND 10 THSD FT AGL...
WITH BKN CLOUDS ABOVE 14 THSD THROUGH 10Z. WEST WINDS WILL DIMINISH
FROM 15 KNOTS AT 04Z WED TO LGT AND VRBL BY 07Z WED. FROM 07Z WED TO
18Z MON...LGT VRBL WNDS. SCT CLDS AOA 10 THSD AGL.



SOUTHWEST ARIZONA AND SOUTHEAST CALIFORNIA INCLUDING KIPL AND KBLH...

THROUGH 18Z WED...MOSTLY CLEAR SKIES. LIGHT WEST TO SOUTHWEST WIND
UNDER 9 KNOTS.

AVIATION DISCUSSION NOT UPDATED FOR AMENDED TAFS.

&&

.FIRE WEATHER...
THURSDAY THROUGH MONDAY...
A SLIGHT CHANCE OF AFTERNOON AND EVENING THUNDERSTORMS WILL CONTINUE
MAINLY EAST OF THE LOWER COLORADO RIVER VALLEY ON THURSDAY WITH A
CHANCE ACROSS THE HIGHER TERRAIN EAST OF PHOENIX. LITTLE CHANGE IS
EXPECTED FRIDAY. HIGH TEMPERATURES BOTH DAYS WILL STAY BELOW
SEASONAL NORMALS...WITH COOLER DESERTS FALLING INTO THE 90S.
HUMIDITY LEVELS WILL STAY QUITE ELEVATED WITH MOST OF THE DESERTS
RECORDING MINIMUM RH VALUES BETWEEN 20 AND 30 PERCENT. A STEADY
SOUTHWEST FLOW ALOFT WILL LEAD TO GRADUAL DRYING AND WARMING
CONDITIONS OVER THE WEEKEND AND INTO EARLY NEXT WEEK. BY SUNDAY
THERE WILL BE JUST A SLIGHT CHANCE OF AFTERNOON AND EVENING
THUNDERSTORMS ACROSS THE HIGHER TERRAIN EAST OF PHOENIX WITH PARTLY
TO MOSTLY SUNNY SKIES EXPECTED ELSEWHERE. DESPITE THE DRYING
TREND...MINIMUM RH VALUES WILL STAY ON THE ELEVATED SIDE AND SHOULD
MOSTLY RANGE FROM 15 TO 25 PERCENT. NO STRONG WINDS ARE EXPECTED
THROUGH THE PERIOD...MAINLY NORMAL DIURNAL WINDS FAVORING THE SOUTH
TO SOUTHWEST LESS THAN 15 MPH.

&&

.PSR WATCHES/WARNINGS/ADVISORIES...

AZ...NONE.

CA...NONE.

&&

$$

VISIT US ON FACEBOOK...TWITTER...AND AT WEATHER.GOV/PHOENIX

DISCUSSION...AJ
AVIATION....VASQUEZ
FIRE WEATHER...CB









000
FXUS65 KPSR 200320 AAA
AFDPSR

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE PHOENIX AZ
820 PM MST TUE AUG 19 2014

.UPDATED...AVIATION DISCUSSION.

&&

.SYNOPSIS...
SCATTERED SHOWERS AND THUNDERSTORMS WILL REMAIN A THREAT THROUGH
THURSDAY AS AN AREA OF LOW PRESSURE MOVES TOWARDS THE DESERT
SOUTHWEST. DRIER AIR SPREADING IN FROM THE WEST WILL REDUCE
THUNDERSTORM ACTIVITY FROM THIS WEEKEND INTO EARLY NEXT WEEK. BELOW
NORMAL TEMPERATURES ARE FORECAST FROM TODAY THROUGH FRIDAY...WARMING
THIS WEEKEND.

&&

.DISCUSSION...
ISOLATED SHOWERS AND THUNDERSTORMS CONTINUED TO LINGER THROUGH PARTS
OF THE PHOENIX AREA AT 730 PM MST IN THE WAKE OF A HEAVY RAIN EVENT
TUESDAY MORNING AND AFTERNOON. THE STRONGEST ACTIVITY AT 730 PM WAS
IN THE PHOENIX WEST VALLEY WHERE A CONVECTIVE WIND GUST TO 53 MPH
WAS MEASURED AT LUKE AFB. ISOLATED CONVECTION SHOULD CONTINUE TO
DEVELOP THE REMAINDER OF THE EVENING...ALONG THE OUTFLOWS WHICH ARE
MOVING EAST INTO A VERY HIGH THETA-E FIELD LAYED DOWN BY MORNING
RAINS. SHOWERS SHOULD END BY MIDNIGHT...BUT A SLIGHT CHANCE WILL
CONTINUE OVERNIGHT.

THE EARLY SEASON COOL PACIFIC LOW PRESSURE SYSTEM DEVELOPING OVER
THE CENTRAL AND SOUTHERN CA COAST...AND RESPONSIBLE FOR A VERY
DYNAMICAL PATTERN AND WIDESPREAD RAIN IN SOUTH CENTRAL AZ TUESDAY
MORNING...WILL BE MOVING INTO AZ BY THURSDAY AFTERNOON...ACCORDING
TO THE GFS MODEL. WE THINK THE GFS SOLUTION IS MORE BELIEVABLE THAN
THE SLOWER MOVING TROF IN THE EUROPEAN MODEL SOLUTION.

THE GFS MODEL CONTINUES TO KEEP AZ UNDER A STRONGER THAN NORMAL
SOUTHWESTERLY FLOW ALOFT AS THE SOUTHERN CA TROF APPROACHES.
SOUTHWESTERLY FLOW ALOFT IS AWAYS WORRISOME...IT CAN EASILY PRODUCE
BOUTS OF UPPER LEVEL SUPPORT/DYNAMICS ANYTIME. SINCE THERE WILL BE
INCREASED SUNSHINE WEDNESDAY...AND HUMIDITY LEVELS WILL CONTINUE IN
THE MONSOON RANGE...THE SLIGHT CHANCE OF SHWR/TSTM FORECAST ACROSS
OUR ENTIRE FORECAST AREA THROUGH WEDNESDAY NIGHT LOOKS OK.

HOWEVER...IF THE GFS MODEL IS CORRECT...THE SOUTHERN CA TROF MOVING
INTO AZ THURSDAY COULD PRODUCE ANOTHER BOUT OF WIDESPREAD SHOWERS
AND THUNDERSTORMS WITH HEAVY RAIN. THE COLD CORE CENTER WITH THE
TROF DROPS 500 MB TEMPERATURES INTO THE MINUS 10 TO 12 RANGE...
UNUSUAL ON THE DESERTS FOR MID AUGUST...ALONG WITH INCREASED UPPER
LEVEL DYNAMICS AND WEAK VERTICAL WIND SHEAR FOR A FEW ORGANIZED
THUNDERSTORMS. AGAIN...THIS IS AN ATYPICAL WEATHER PATTERN FOR
SOUTHWEST AND SOUTH CENTRAL AZ AND SHOULDNT BE DISCOUNTED.

WE WILL PASS THIS ANALYSIS TO THE MID SHIFT FOR FURTHER REVIEW SINCE
A NEW FORECAST PACKAGE WILL BE ISSUED. A NEW EUROPEAN MODEL FORECAST
INTO OUR COMPUTERS SHORTLY AFTER MIDNIGHT MAY CONFIRM THE ABOVE
THINKING.

OTHERWISE...FORECASTS LOOK OK. NO UPDATES PLANNED. PREVIOUS
DISCUSSION BELOW STILL APPLIES.



.PREVIOUS DISCUSSION...330 PM MST...
HISTORIC RAIN AND FLOODING OCCURRED ACROSS PORTIONS OF THE PHOENIX
AREA TODAY. THE BIGGEST IMPACT WAS FELT ACROSS NORTHERN MARICOPA
COUNTY WHERE WIDESPREAD RAIN TOTALS OF 2 TO 5 INCHES WERE MEASURED.
A SECOND LINE OF STORMS DEVELOPED EARLY THIS AFTERNOON WHICH
PRODUCED AN ADDITIONAL HALF INCH TO ONE INCH OF RAIN ACROSS CENTRAL
AND NORTH PHOENIX. ELEVATED STREAMFLOWS WERE ALSO OBSERVED ACROSS
THE AGUA FRIA RIVER...SKUNK CREEK AND CAVE CREEK. THE AGUA FRIA
BRIEFLY CRESTED INTO THE MAJOR FLOOD CATEGORY BUT CONTINUES TO
RECEDE. MEANWHILE...CAVE CREEK REACHED A STAGE OF 12.75
FT...ECLIPSING THE PREVIOUS RECORD OF 12.1 FT FROM THE RAIN EVENT
IN JANUARY 2010.

LATEST WV IMAGERY SHOWS DRIER AIR WORKING ITS WAY INTO SOUTHWESTERN
AZ ASSOCIATED WITH THE CYCLONIC FLOW AROUND THE CLOSED LOW ALONG THE
CENTRAL CA COAST. DEWPOINTS CONTINUE TO DROP MAINLY WEST OF MARICOPA
COUNTY...THOUGH EVEN THE GPS-IPW AT TEMPE HAS DROPPED TO 1.6 INCHES.
NEVERTHELESS....SHOWERS HAVE REDEVELOPED ACROSS THE FAVORED HIGHER
TERRAIN AREAS OF EASTERN LA PAZ AND NORTHERN MARICOPA COUNTY. LATEST
MESOANALYSIS SHOWS WIDESPREAD CAPES ABOVE 500 J/KG WITH MINIMAL
INHIBITION STRETCHING FROM EASTERN RIVERSIDE COUNTY TO EASTERN AZ.
LATEST GLOBAL AND CONVECTIVE ALLOWING GUIDANCE SUGGESTS THE MOST
FAVORED AREA FOR ADDITIONAL STORMS WILL BE ACROSS NORTHWESTERN
MARICOPA COUNTY WHERE THE EXISTING INSTABILITY IS JUXTAPOSED WITH
STRONGER THAN NORMAL DEEP LAYER SHEAR. SHOWERS AND THUNDERSTORMS
WILL DISSIPATE THIS EVENING AS CONDITIONS STABILIZE RAPIDLY.

&&

.PREVIOUS DISCUSSION...
WEDNESDAY AND WEDNESDAY NIGHT...
A SIGNIFICANT REDUCTION IN SHOWER/THUNDERSTORM ACTIVITY IS EXPECTED
ON WEDNESDAY AND WEDNESDAY NIGHT AS PWATS FALL INTO THE 1.25-150
INCH RANGE AS SOUTHWESTERLY FLOW ALOFT STRENGTHENS OVER THE REGION
AHEAD OF THE MAIN UPPER LOW CENTER. STILL...ISOLATED TO SCATTERED
STORMS CAN BE EXPECTED...WITH THE BEST CHANCES FOR STORMS BEING OVER
THE HIGHER TERRAIN NORTH AND EAST OF PHOENIX AS STRONGER WINDS ALOFT
INCREASES BULK SHEAR VALUES OVER THE REGION.

THURSDAY AND FRIDAY...
THE LIKELIHOOD OF A SECOND HEAVY RAIN EVENT ON THURSDAY/FRIDAY NOW
LOOKS TO BE SIGNIFICANTLY LESS...SINCE LATEST MODELS RUNS ARE NOW
SHOWING MUCH LESS TROPICAL MOISTURE...FROM TROPICAL STORM
LOWELL...BEING PULLED NORTHEASTWARD INTO THE REGION. THUS...HAVE
REDUCED POPS SOMEWHAT ON THU/FRI...BUT STILL KEEPING THINGS
BROADBRUSHED A BIT...SINCE THE EURO CONTINUES TO BE SLOWER WITH THE
MOVEMENT OF THE UPPER LOW CENTER...TAKING IT ACROSS AZ ON
FRIDAY...WHILE THE FASTER GFS CONTINUES TO MOVE IT THROUGH ON
THURSDAY.

SATURDAY THROUGH TUESDAY...
THE COMBINATION OF A DRIER WESTERLY FLOW ALONG WITH RIDGING ALOFT
WILL LIKELY KEEP CHANCES FOR THUNDERSTORM ACTIVITY AT CLIMO...OR
BELOW LEVELS DURING THIS PERIOD. HOWEVER...IT STILL APPEARS THAT
THERE WILL BE ENOUGH RESIDUAL MOISTURE AROUND TO KEEP US FROM
ELIMINATING CHANCES FOR POPS ENTIRELY AT THIS POINT...WITH
TEMPERATURES RETURNING TO NEAR...OR SLIGHTLY ABOVE NORMAL VALUES.

&&

.AVIATION...
SOUTH-CENTRAL ARIZONA INCLUDING KPHX...KIWA...AND KSDL...

ISOLATED SHOWERS AND THUNDERSTORMS WILL CONTINUE ACROSS THE PHOENIX
VALLEY THROUGH 06Z. SCT CLOUD DECKS BTWN 6 AND 10 THSD FT AGL...
WITH BKN CLOUDS ABOVE 14 THSD THROUGH 10Z. WEST WINDS WILL DIMINISH
FROM 15 KNOTS AT 04Z WED TO LGT AND VRBL BY 07Z WED. FROM 07Z WED TO
18Z MON...LGT VRBL WNDS. SCT CLDS AOA 10 THSD AGL.



SOUTHWEST ARIZONA AND SOUTHEAST CALIFORNIA INCLUDING KIPL AND KBLH...

THROUGH 18Z WED...MOSTLY CLEAR SKIES. LIGHT WEST TO SOUTHWEST WIND
UNDER 9 KNOTS.

AVIATION DISCUSSION NOT UPDATED FOR AMENDED TAFS.

&&

.FIRE WEATHER...
THURSDAY THROUGH MONDAY...
A SLIGHT CHANCE OF AFTERNOON AND EVENING THUNDERSTORMS WILL CONTINUE
MAINLY EAST OF THE LOWER COLORADO RIVER VALLEY ON THURSDAY WITH A
CHANCE ACROSS THE HIGHER TERRAIN EAST OF PHOENIX. LITTLE CHANGE IS
EXPECTED FRIDAY. HIGH TEMPERATURES BOTH DAYS WILL STAY BELOW
SEASONAL NORMALS...WITH COOLER DESERTS FALLING INTO THE 90S.
HUMIDITY LEVELS WILL STAY QUITE ELEVATED WITH MOST OF THE DESERTS
RECORDING MINIMUM RH VALUES BETWEEN 20 AND 30 PERCENT. A STEADY
SOUTHWEST FLOW ALOFT WILL LEAD TO GRADUAL DRYING AND WARMING
CONDITIONS OVER THE WEEKEND AND INTO EARLY NEXT WEEK. BY SUNDAY
THERE WILL BE JUST A SLIGHT CHANCE OF AFTERNOON AND EVENING
THUNDERSTORMS ACROSS THE HIGHER TERRAIN EAST OF PHOENIX WITH PARTLY
TO MOSTLY SUNNY SKIES EXPECTED ELSEWHERE. DESPITE THE DRYING
TREND...MINIMUM RH VALUES WILL STAY ON THE ELEVATED SIDE AND SHOULD
MOSTLY RANGE FROM 15 TO 25 PERCENT. NO STRONG WINDS ARE EXPECTED
THROUGH THE PERIOD...MAINLY NORMAL DIURNAL WINDS FAVORING THE SOUTH
TO SOUTHWEST LESS THAN 15 MPH.

&&

.PSR WATCHES/WARNINGS/ADVISORIES...

AZ...NONE.

CA...NONE.

&&

$$

VISIT US ON FACEBOOK...TWITTER...AND AT WEATHER.GOV/PHOENIX

DISCUSSION...VASQUEZ/PERCHA
AVIATION....VASQUEZ
FIRE WEATHER...CB










000
FXUS65 KPSR 200320 AAA
AFDPSR

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE PHOENIX AZ
820 PM MST TUE AUG 19 2014

.UPDATED...AVIATION DISCUSSION.

&&

.SYNOPSIS...
SCATTERED SHOWERS AND THUNDERSTORMS WILL REMAIN A THREAT THROUGH
THURSDAY AS AN AREA OF LOW PRESSURE MOVES TOWARDS THE DESERT
SOUTHWEST. DRIER AIR SPREADING IN FROM THE WEST WILL REDUCE
THUNDERSTORM ACTIVITY FROM THIS WEEKEND INTO EARLY NEXT WEEK. BELOW
NORMAL TEMPERATURES ARE FORECAST FROM TODAY THROUGH FRIDAY...WARMING
THIS WEEKEND.

&&

.DISCUSSION...
ISOLATED SHOWERS AND THUNDERSTORMS CONTINUED TO LINGER THROUGH PARTS
OF THE PHOENIX AREA AT 730 PM MST IN THE WAKE OF A HEAVY RAIN EVENT
TUESDAY MORNING AND AFTERNOON. THE STRONGEST ACTIVITY AT 730 PM WAS
IN THE PHOENIX WEST VALLEY WHERE A CONVECTIVE WIND GUST TO 53 MPH
WAS MEASURED AT LUKE AFB. ISOLATED CONVECTION SHOULD CONTINUE TO
DEVELOP THE REMAINDER OF THE EVENING...ALONG THE OUTFLOWS WHICH ARE
MOVING EAST INTO A VERY HIGH THETA-E FIELD LAYED DOWN BY MORNING
RAINS. SHOWERS SHOULD END BY MIDNIGHT...BUT A SLIGHT CHANCE WILL
CONTINUE OVERNIGHT.

THE EARLY SEASON COOL PACIFIC LOW PRESSURE SYSTEM DEVELOPING OVER
THE CENTRAL AND SOUTHERN CA COAST...AND RESPONSIBLE FOR A VERY
DYNAMICAL PATTERN AND WIDESPREAD RAIN IN SOUTH CENTRAL AZ TUESDAY
MORNING...WILL BE MOVING INTO AZ BY THURSDAY AFTERNOON...ACCORDING
TO THE GFS MODEL. WE THINK THE GFS SOLUTION IS MORE BELIEVABLE THAN
THE SLOWER MOVING TROF IN THE EUROPEAN MODEL SOLUTION.

THE GFS MODEL CONTINUES TO KEEP AZ UNDER A STRONGER THAN NORMAL
SOUTHWESTERLY FLOW ALOFT AS THE SOUTHERN CA TROF APPROACHES.
SOUTHWESTERLY FLOW ALOFT IS AWAYS WORRISOME...IT CAN EASILY PRODUCE
BOUTS OF UPPER LEVEL SUPPORT/DYNAMICS ANYTIME. SINCE THERE WILL BE
INCREASED SUNSHINE WEDNESDAY...AND HUMIDITY LEVELS WILL CONTINUE IN
THE MONSOON RANGE...THE SLIGHT CHANCE OF SHWR/TSTM FORECAST ACROSS
OUR ENTIRE FORECAST AREA THROUGH WEDNESDAY NIGHT LOOKS OK.

HOWEVER...IF THE GFS MODEL IS CORRECT...THE SOUTHERN CA TROF MOVING
INTO AZ THURSDAY COULD PRODUCE ANOTHER BOUT OF WIDESPREAD SHOWERS
AND THUNDERSTORMS WITH HEAVY RAIN. THE COLD CORE CENTER WITH THE
TROF DROPS 500 MB TEMPERATURES INTO THE MINUS 10 TO 12 RANGE...
UNUSUAL ON THE DESERTS FOR MID AUGUST...ALONG WITH INCREASED UPPER
LEVEL DYNAMICS AND WEAK VERTICAL WIND SHEAR FOR A FEW ORGANIZED
THUNDERSTORMS. AGAIN...THIS IS AN ATYPICAL WEATHER PATTERN FOR
SOUTHWEST AND SOUTH CENTRAL AZ AND SHOULDNT BE DISCOUNTED.

WE WILL PASS THIS ANALYSIS TO THE MID SHIFT FOR FURTHER REVIEW SINCE
A NEW FORECAST PACKAGE WILL BE ISSUED. A NEW EUROPEAN MODEL FORECAST
INTO OUR COMPUTERS SHORTLY AFTER MIDNIGHT MAY CONFIRM THE ABOVE
THINKING.

OTHERWISE...FORECASTS LOOK OK. NO UPDATES PLANNED. PREVIOUS
DISCUSSION BELOW STILL APPLIES.



.PREVIOUS DISCUSSION...330 PM MST...
HISTORIC RAIN AND FLOODING OCCURRED ACROSS PORTIONS OF THE PHOENIX
AREA TODAY. THE BIGGEST IMPACT WAS FELT ACROSS NORTHERN MARICOPA
COUNTY WHERE WIDESPREAD RAIN TOTALS OF 2 TO 5 INCHES WERE MEASURED.
A SECOND LINE OF STORMS DEVELOPED EARLY THIS AFTERNOON WHICH
PRODUCED AN ADDITIONAL HALF INCH TO ONE INCH OF RAIN ACROSS CENTRAL
AND NORTH PHOENIX. ELEVATED STREAMFLOWS WERE ALSO OBSERVED ACROSS
THE AGUA FRIA RIVER...SKUNK CREEK AND CAVE CREEK. THE AGUA FRIA
BRIEFLY CRESTED INTO THE MAJOR FLOOD CATEGORY BUT CONTINUES TO
RECEDE. MEANWHILE...CAVE CREEK REACHED A STAGE OF 12.75
FT...ECLIPSING THE PREVIOUS RECORD OF 12.1 FT FROM THE RAIN EVENT
IN JANUARY 2010.

LATEST WV IMAGERY SHOWS DRIER AIR WORKING ITS WAY INTO SOUTHWESTERN
AZ ASSOCIATED WITH THE CYCLONIC FLOW AROUND THE CLOSED LOW ALONG THE
CENTRAL CA COAST. DEWPOINTS CONTINUE TO DROP MAINLY WEST OF MARICOPA
COUNTY...THOUGH EVEN THE GPS-IPW AT TEMPE HAS DROPPED TO 1.6 INCHES.
NEVERTHELESS....SHOWERS HAVE REDEVELOPED ACROSS THE FAVORED HIGHER
TERRAIN AREAS OF EASTERN LA PAZ AND NORTHERN MARICOPA COUNTY. LATEST
MESOANALYSIS SHOWS WIDESPREAD CAPES ABOVE 500 J/KG WITH MINIMAL
INHIBITION STRETCHING FROM EASTERN RIVERSIDE COUNTY TO EASTERN AZ.
LATEST GLOBAL AND CONVECTIVE ALLOWING GUIDANCE SUGGESTS THE MOST
FAVORED AREA FOR ADDITIONAL STORMS WILL BE ACROSS NORTHWESTERN
MARICOPA COUNTY WHERE THE EXISTING INSTABILITY IS JUXTAPOSED WITH
STRONGER THAN NORMAL DEEP LAYER SHEAR. SHOWERS AND THUNDERSTORMS
WILL DISSIPATE THIS EVENING AS CONDITIONS STABILIZE RAPIDLY.

&&

.PREVIOUS DISCUSSION...
WEDNESDAY AND WEDNESDAY NIGHT...
A SIGNIFICANT REDUCTION IN SHOWER/THUNDERSTORM ACTIVITY IS EXPECTED
ON WEDNESDAY AND WEDNESDAY NIGHT AS PWATS FALL INTO THE 1.25-150
INCH RANGE AS SOUTHWESTERLY FLOW ALOFT STRENGTHENS OVER THE REGION
AHEAD OF THE MAIN UPPER LOW CENTER. STILL...ISOLATED TO SCATTERED
STORMS CAN BE EXPECTED...WITH THE BEST CHANCES FOR STORMS BEING OVER
THE HIGHER TERRAIN NORTH AND EAST OF PHOENIX AS STRONGER WINDS ALOFT
INCREASES BULK SHEAR VALUES OVER THE REGION.

THURSDAY AND FRIDAY...
THE LIKELIHOOD OF A SECOND HEAVY RAIN EVENT ON THURSDAY/FRIDAY NOW
LOOKS TO BE SIGNIFICANTLY LESS...SINCE LATEST MODELS RUNS ARE NOW
SHOWING MUCH LESS TROPICAL MOISTURE...FROM TROPICAL STORM
LOWELL...BEING PULLED NORTHEASTWARD INTO THE REGION. THUS...HAVE
REDUCED POPS SOMEWHAT ON THU/FRI...BUT STILL KEEPING THINGS
BROADBRUSHED A BIT...SINCE THE EURO CONTINUES TO BE SLOWER WITH THE
MOVEMENT OF THE UPPER LOW CENTER...TAKING IT ACROSS AZ ON
FRIDAY...WHILE THE FASTER GFS CONTINUES TO MOVE IT THROUGH ON
THURSDAY.

SATURDAY THROUGH TUESDAY...
THE COMBINATION OF A DRIER WESTERLY FLOW ALONG WITH RIDGING ALOFT
WILL LIKELY KEEP CHANCES FOR THUNDERSTORM ACTIVITY AT CLIMO...OR
BELOW LEVELS DURING THIS PERIOD. HOWEVER...IT STILL APPEARS THAT
THERE WILL BE ENOUGH RESIDUAL MOISTURE AROUND TO KEEP US FROM
ELIMINATING CHANCES FOR POPS ENTIRELY AT THIS POINT...WITH
TEMPERATURES RETURNING TO NEAR...OR SLIGHTLY ABOVE NORMAL VALUES.

&&

.AVIATION...
SOUTH-CENTRAL ARIZONA INCLUDING KPHX...KIWA...AND KSDL...

ISOLATED SHOWERS AND THUNDERSTORMS WILL CONTINUE ACROSS THE PHOENIX
VALLEY THROUGH 06Z. SCT CLOUD DECKS BTWN 6 AND 10 THSD FT AGL...
WITH BKN CLOUDS ABOVE 14 THSD THROUGH 10Z. WEST WINDS WILL DIMINISH
FROM 15 KNOTS AT 04Z WED TO LGT AND VRBL BY 07Z WED. FROM 07Z WED TO
18Z MON...LGT VRBL WNDS. SCT CLDS AOA 10 THSD AGL.



SOUTHWEST ARIZONA AND SOUTHEAST CALIFORNIA INCLUDING KIPL AND KBLH...

THROUGH 18Z WED...MOSTLY CLEAR SKIES. LIGHT WEST TO SOUTHWEST WIND
UNDER 9 KNOTS.

AVIATION DISCUSSION NOT UPDATED FOR AMENDED TAFS.

&&

.FIRE WEATHER...
THURSDAY THROUGH MONDAY...
A SLIGHT CHANCE OF AFTERNOON AND EVENING THUNDERSTORMS WILL CONTINUE
MAINLY EAST OF THE LOWER COLORADO RIVER VALLEY ON THURSDAY WITH A
CHANCE ACROSS THE HIGHER TERRAIN EAST OF PHOENIX. LITTLE CHANGE IS
EXPECTED FRIDAY. HIGH TEMPERATURES BOTH DAYS WILL STAY BELOW
SEASONAL NORMALS...WITH COOLER DESERTS FALLING INTO THE 90S.
HUMIDITY LEVELS WILL STAY QUITE ELEVATED WITH MOST OF THE DESERTS
RECORDING MINIMUM RH VALUES BETWEEN 20 AND 30 PERCENT. A STEADY
SOUTHWEST FLOW ALOFT WILL LEAD TO GRADUAL DRYING AND WARMING
CONDITIONS OVER THE WEEKEND AND INTO EARLY NEXT WEEK. BY SUNDAY
THERE WILL BE JUST A SLIGHT CHANCE OF AFTERNOON AND EVENING
THUNDERSTORMS ACROSS THE HIGHER TERRAIN EAST OF PHOENIX WITH PARTLY
TO MOSTLY SUNNY SKIES EXPECTED ELSEWHERE. DESPITE THE DRYING
TREND...MINIMUM RH VALUES WILL STAY ON THE ELEVATED SIDE AND SHOULD
MOSTLY RANGE FROM 15 TO 25 PERCENT. NO STRONG WINDS ARE EXPECTED
THROUGH THE PERIOD...MAINLY NORMAL DIURNAL WINDS FAVORING THE SOUTH
TO SOUTHWEST LESS THAN 15 MPH.

&&

.PSR WATCHES/WARNINGS/ADVISORIES...

AZ...NONE.

CA...NONE.

&&

$$

VISIT US ON FACEBOOK...TWITTER...AND AT WEATHER.GOV/PHOENIX

DISCUSSION...VASQUEZ/PERCHA
AVIATION....VASQUEZ
FIRE WEATHER...CB











000
FXUS65 KPSR 200315
AFDPSR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PHOENIX AZ
815 PM MST TUE AUG 19 2014

.SYNOPSIS...
SCATTERED SHOWERS AND THUNDERSTORMS WILL REMAIN A THREAT THROUGH
THURSDAY AS AN AREA OF LOW PRESSURE MOVES TOWARDS THE DESERT
SOUTHWEST. DRIER AIR SPREADING IN FROM THE WEST WILL REDUCE
THUNDERSTORM ACTIVITY FROM THIS WEEKEND INTO EARLY NEXT WEEK. BELOW
NORMAL TEMPERATURES ARE FORECAST FROM TODAY THROUGH FRIDAY...WARMING
THIS WEEKEND.

&&

.DISCUSSION...
ISOLATED SHOWERS AND THUNDERSTORMS CONTINUED TO LINGER THROUGH PARTS
OF THE PHOENIX AREA AT 730 PM MST IN THE WAKE OF A HEAVY RAIN EVENT
TUESDAY MORNING AND AFTERNOON. THE STRONGEST ACTIVITY AT 730 PM WAS
IN THE PHOENIX WEST VALLEY WHERE A CONVECTIVE WIND GUST TO 53 MPH
WAS MEASURED AT LUKE AFB. ISOLATED CONVECTION SHOULD CONTINUE TO
DEVELOP THE REMAINDER OF THE EVENING...ALONG THE OUTFLOWS WHICH ARE
MOVING EAST INTO A VERY HIGH THETA-E FIELD LAYED DOWN BY MORNING
RAINS. SHOWERS SHOULD END BY MIDNIGHT...BUT A SLIGHT CHANCE WILL
CONTINUE OVERNIGHT.

THE EARLY SEASON COOL PACIFIC LOW PRESSURE SYSTEM DEVELOPING OVER
THE CENTRAL AND SOUTHERN CA COAST...AND RESPONSIBLE FOR A VERY
DYNAMICAL PATTERN AND WIDESPREAD RAIN IN SOUTH CENTRAL AZ TUESDAY
MORNING...WILL BE MOVING INTO AZ BY THURSDAY AFTERNOON...ACCORDING
TO THE GFS MODEL. WE THINK THE GFS SOLUTION IS MORE BELIEVABLE THAN
THE SLOWER MOVING TROF IN THE EUROPEAN MODEL SOLUTION.

THE GFS MODEL CONTINUES TO KEEP AZ UNDER A STRONGER THAN NORMAL
SOUTHWESTERLY FLOW ALOFT AS THE SOUTHERN CA TROF APPROACHES.
SOUTHWESTERLY FLOW ALOFT IS AWAYS WORRISOME...IT CAN EASILY PRODUCE
BOUTS OF UPPER LEVEL SUPPORT/DYNAMICS ANYTIME. SINCE THERE WILL BE
INCREASED SUNSHINE WEDNESDAY...AND HUMIDITY LEVELS WILL CONTINUE IN
THE MONSOON RANGE...THE SLIGHT CHANCE OF SHWR/TSTM FORECAST ACROSS
OUR ENTIRE FORECAST AREA THROUGH WEDNESDAY NIGHT LOOKS OK.

HOWEVER...IF THE GFS MODEL IS CORRECT...THE SOUTHERN CA TROF MOVING
INTO AZ THURSDAY COULD PRODUCE ANOTHER BOUT OF WIDESPREAD SHOWERS
AND THUNDERSTORMS WITH HEAVY RAIN. THE COLD CORE CENTER WITH THE
TROF DROPS 500 MB TEMPERATURES INTO THE MINUS 10 TO 12 RANGE...
UNUSUAL ON THE DESERTS FOR MID AUGUST...ALONG WITH INCREASED UPPER
LEVEL DYNAMICS AND WEAK VERTICAL WIND SHEAR FOR A FEW ORGANIZED
THUNDERSTORMS. AGAIN...THIS IS AN ATYPICAL WEATHER PATTERN FOR
SOUTHWEST AND SOUTH CENTRAL AZ AND SHOULDNT BE DISCOUNTED.

WE WILL PASS THIS ANALYSIS TO THE MID SHIFT FOR FURTHER REVIEW SINCE
A NEW FORECAST PACKAGE WILL BE ISSUED. A NEW EUROPEAN MODEL FORECAST
INTO OUR COMPUTERS SHORTLY AFTER MIDNIGHT MAY CONFIRM THE ABOVE
THINKING.

OTHERWISE...FORECASTS LOOK OK. NO UPDATES PLANNED. PREVIOUS
DISCUSSION BELOW STILL APPLIES.



.PREVIOUS DISCUSSION...330 PM MST...
HISTORIC RAIN AND FLOODING OCCURRED ACROSS PORTIONS OF THE PHOENIX
AREA TODAY. THE BIGGEST IMPACT WAS FELT ACROSS NORTHERN MARICOPA
COUNTY WHERE WIDESPREAD RAIN TOTALS OF 2 TO 5 INCHES WERE MEASURED.
A SECOND LINE OF STORMS DEVELOPED EARLY THIS AFTERNOON WHICH
PRODUCED AN ADDITIONAL HALF INCH TO ONE INCH OF RAIN ACROSS CENTRAL
AND NORTH PHOENIX. ELEVATED STREAMFLOWS WERE ALSO OBSERVED ACROSS
THE AGUA FRIA RIVER...SKUNK CREEK AND CAVE CREEK. THE AGUA FRIA
BRIEFLY CRESTED INTO THE MAJOR FLOOD CATEGORY BUT CONTINUES TO
RECEDE. MEANWHILE...CAVE CREEK REACHED A STAGE OF 12.75
FT...ECLIPSING THE PREVIOUS RECORD OF 12.1 FT FROM THE RAIN EVENT
IN JANUARY 2010.

LATEST WV IMAGERY SHOWS DRIER AIR WORKING ITS WAY INTO SOUTHWESTERN
AZ ASSOCIATED WITH THE CYCLONIC FLOW AROUND THE CLOSED LOW ALONG THE
CENTRAL CA COAST. DEWPOINTS CONTINUE TO DROP MAINLY WEST OF MARICOPA
COUNTY...THOUGH EVEN THE GPS-IPW AT TEMPE HAS DROPPED TO 1.6 INCHES.
NEVERTHELESS....SHOWERS HAVE REDEVELOPED ACROSS THE FAVORED HIGHER
TERRAIN AREAS OF EASTERN LA PAZ AND NORTHERN MARICOPA COUNTY. LATEST
MESOANALYSIS SHOWS WIDESPREAD CAPES ABOVE 500 J/KG WITH MINIMAL
INHIBITION STRETCHING FROM EASTERN RIVERSIDE COUNTY TO EASTERN AZ.
LATEST GLOBAL AND CONVECTIVE ALLOWING GUIDANCE SUGGESTS THE MOST
FAVORED AREA FOR ADDITIONAL STORMS WILL BE ACROSS NORTHWESTERN
MARICOPA COUNTY WHERE THE EXISTING INSTABILITY IS JUXTAPOSED WITH
STRONGER THAN NORMAL DEEP LAYER SHEAR. SHOWERS AND THUNDERSTORMS
WILL DISSIPATE THIS EVENING AS CONDITIONS STABILIZE RAPIDLY.

&&

.PREVIOUS DISCUSSION...
WEDNESDAY AND WEDNESDAY NIGHT...
A SIGNIFICANT REDUCTION IN SHOWER/THUNDERSTORM ACTIVITY IS EXPECTED
ON WEDNESDAY AND WEDNESDAY NIGHT AS PWATS FALL INTO THE 1.25-150
INCH RANGE AS SOUTHWESTERLY FLOW ALOFT STRENGTHENS OVER THE REGION
AHEAD OF THE MAIN UPPER LOW CENTER. STILL...ISOLATED TO SCATTERED
STORMS CAN BE EXPECTED...WITH THE BEST CHANCES FOR STORMS BEING OVER
THE HIGHER TERRAIN NORTH AND EAST OF PHOENIX AS STRONGER WINDS ALOFT
INCREASES BULK SHEAR VALUES OVER THE REGION.

THURSDAY AND FRIDAY...
THE LIKELIHOOD OF A SECOND HEAVY RAIN EVENT ON THURSDAY/FRIDAY NOW
LOOKS TO BE SIGNIFICANTLY LESS...SINCE LATEST MODELS RUNS ARE NOW
SHOWING MUCH LESS TROPICAL MOISTURE...FROM TROPICAL STORM
LOWELL...BEING PULLED NORTHEASTWARD INTO THE REGION. THUS...HAVE
REDUCED POPS SOMEWHAT ON THU/FRI...BUT STILL KEEPING THINGS
BROADBRUSHED A BIT...SINCE THE EURO CONTINUES TO BE SLOWER WITH THE
MOVEMENT OF THE UPPER LOW CENTER...TAKING IT ACROSS AZ ON
FRIDAY...WHILE THE FASTER GFS CONTINUES TO MOVE IT THROUGH ON
THURSDAY.

SATURDAY THROUGH TUESDAY...
THE COMBINATION OF A DRIER WESTERLY FLOW ALONG WITH RIDGING ALOFT
WILL LIKELY KEEP CHANCES FOR THUNDERSTORM ACTIVITY AT CLIMO...OR
BELOW LEVELS DURING THIS PERIOD. HOWEVER...IT STILL APPEARS THAT
THERE WILL BE ENOUGH RESIDUAL MOISTURE AROUND TO KEEP US FROM
ELIMINATING CHANCES FOR POPS ENTIRELY AT THIS POINT...WITH
TEMPERATURES RETURNING TO NEAR...OR SLIGHTLY ABOVE NORMAL VALUES.

&&

.AVIATION...
SOUTH-CENTRAL ARIZONA INCLUDING KPHX...KIWA...AND KSDL...

CLEARING SKIES AND IMPROVING CIGS THIS AFTERNOON AND EVENING AS
DRIER AIR BEGINS TO OVERSPREAD THE AREA. SCT CLOUD DECKS GENERALLY
AOA 6000FT...OCCASIONALLY BKN AROUND 10-12KFT OVERNIGHT INTO
WEDNESDAY MORNING. WINDS SHOULD FAVOR NORTHWEST AT TERMINALS UNTIL
02Z...THEN BECOME EASTERLY OVERNIGHT.

SOUTHWEST ARIZONA AND SOUTHEAST CALIFORNIA INCLUDING KIPL AND KBLH...

MOSTLY CLEAR SKIES THIS EVENING AND OVERNIGHT...WINDS LIGHT 12KT OR
LESS AT TERMINALS...FAVORING SOUTHWEST-WEST OVERNIGHT INTO WEDNESDAY
MORNING.

AVIATION DISCUSSION NOT UPDATED FOR AMENDED TAFS.

&&

.FIRE WEATHER...
THURSDAY THROUGH MONDAY...
A SLIGHT CHANCE OF AFTERNOON AND EVENING THUNDERSTORMS WILL CONTINUE
MAINLY EAST OF THE LOWER COLORADO RIVER VALLEY ON THURSDAY WITH A
CHANCE ACROSS THE HIGHER TERRAIN EAST OF PHOENIX. LITTLE CHANGE IS
EXPECTED FRIDAY. HIGH TEMPERATURES BOTH DAYS WILL STAY BELOW
SEASONAL NORMALS...WITH COOLER DESERTS FALLING INTO THE 90S.
HUMIDITY LEVELS WILL STAY QUITE ELEVATED WITH MOST OF THE DESERTS
RECORDING MINIMUM RH VALUES BETWEEN 20 AND 30 PERCENT. A STEADY
SOUTHWEST FLOW ALOFT WILL LEAD TO GRADUAL DRYING AND WARMING
CONDITIONS OVER THE WEEKEND AND INTO EARLY NEXT WEEK. BY SUNDAY
THERE WILL BE JUST A SLIGHT CHANCE OF AFTERNOON AND EVENING
THUNDERSTORMS ACROSS THE HIGHER TERRAIN EAST OF PHOENIX WITH PARTLY
TO MOSTLY SUNNY SKIES EXPECTED ELSEWHERE. DESPITE THE DRYING
TREND...MINIMUM RH VALUES WILL STAY ON THE ELEVATED SIDE AND SHOULD
MOSTLY RANGE FROM 15 TO 25 PERCENT. NO STRONG WINDS ARE EXPECTED
THROUGH THE PERIOD...MAINLY NORMAL DIURNAL WINDS FAVORING THE SOUTH
TO SOUTHWEST LESS THAN 15 MPH.

&&

.PSR WATCHES/WARNINGS/ADVISORIES...

AZ...NONE.

CA...NONE.

&&

$$

VISIT US ON FACEBOOK...TWITTER...AND AT WEATHER.GOV/PHOENIX

DISCUSSION...VASQUEZ/PERCHA
AVIATION....VASQUEZ
FIRE WEATHER...CB









000
FXUS65 KPSR 200315
AFDPSR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PHOENIX AZ
815 PM MST TUE AUG 19 2014

.SYNOPSIS...
SCATTERED SHOWERS AND THUNDERSTORMS WILL REMAIN A THREAT THROUGH
THURSDAY AS AN AREA OF LOW PRESSURE MOVES TOWARDS THE DESERT
SOUTHWEST. DRIER AIR SPREADING IN FROM THE WEST WILL REDUCE
THUNDERSTORM ACTIVITY FROM THIS WEEKEND INTO EARLY NEXT WEEK. BELOW
NORMAL TEMPERATURES ARE FORECAST FROM TODAY THROUGH FRIDAY...WARMING
THIS WEEKEND.

&&

.DISCUSSION...
ISOLATED SHOWERS AND THUNDERSTORMS CONTINUED TO LINGER THROUGH PARTS
OF THE PHOENIX AREA AT 730 PM MST IN THE WAKE OF A HEAVY RAIN EVENT
TUESDAY MORNING AND AFTERNOON. THE STRONGEST ACTIVITY AT 730 PM WAS
IN THE PHOENIX WEST VALLEY WHERE A CONVECTIVE WIND GUST TO 53 MPH
WAS MEASURED AT LUKE AFB. ISOLATED CONVECTION SHOULD CONTINUE TO
DEVELOP THE REMAINDER OF THE EVENING...ALONG THE OUTFLOWS WHICH ARE
MOVING EAST INTO A VERY HIGH THETA-E FIELD LAYED DOWN BY MORNING
RAINS. SHOWERS SHOULD END BY MIDNIGHT...BUT A SLIGHT CHANCE WILL
CONTINUE OVERNIGHT.

THE EARLY SEASON COOL PACIFIC LOW PRESSURE SYSTEM DEVELOPING OVER
THE CENTRAL AND SOUTHERN CA COAST...AND RESPONSIBLE FOR A VERY
DYNAMICAL PATTERN AND WIDESPREAD RAIN IN SOUTH CENTRAL AZ TUESDAY
MORNING...WILL BE MOVING INTO AZ BY THURSDAY AFTERNOON...ACCORDING
TO THE GFS MODEL. WE THINK THE GFS SOLUTION IS MORE BELIEVABLE THAN
THE SLOWER MOVING TROF IN THE EUROPEAN MODEL SOLUTION.

THE GFS MODEL CONTINUES TO KEEP AZ UNDER A STRONGER THAN NORMAL
SOUTHWESTERLY FLOW ALOFT AS THE SOUTHERN CA TROF APPROACHES.
SOUTHWESTERLY FLOW ALOFT IS AWAYS WORRISOME...IT CAN EASILY PRODUCE
BOUTS OF UPPER LEVEL SUPPORT/DYNAMICS ANYTIME. SINCE THERE WILL BE
INCREASED SUNSHINE WEDNESDAY...AND HUMIDITY LEVELS WILL CONTINUE IN
THE MONSOON RANGE...THE SLIGHT CHANCE OF SHWR/TSTM FORECAST ACROSS
OUR ENTIRE FORECAST AREA THROUGH WEDNESDAY NIGHT LOOKS OK.

HOWEVER...IF THE GFS MODEL IS CORRECT...THE SOUTHERN CA TROF MOVING
INTO AZ THURSDAY COULD PRODUCE ANOTHER BOUT OF WIDESPREAD SHOWERS
AND THUNDERSTORMS WITH HEAVY RAIN. THE COLD CORE CENTER WITH THE
TROF DROPS 500 MB TEMPERATURES INTO THE MINUS 10 TO 12 RANGE...
UNUSUAL ON THE DESERTS FOR MID AUGUST...ALONG WITH INCREASED UPPER
LEVEL DYNAMICS AND WEAK VERTICAL WIND SHEAR FOR A FEW ORGANIZED
THUNDERSTORMS. AGAIN...THIS IS AN ATYPICAL WEATHER PATTERN FOR
SOUTHWEST AND SOUTH CENTRAL AZ AND SHOULDNT BE DISCOUNTED.

WE WILL PASS THIS ANALYSIS TO THE MID SHIFT FOR FURTHER REVIEW SINCE
A NEW FORECAST PACKAGE WILL BE ISSUED. A NEW EUROPEAN MODEL FORECAST
INTO OUR COMPUTERS SHORTLY AFTER MIDNIGHT MAY CONFIRM THE ABOVE
THINKING.

OTHERWISE...FORECASTS LOOK OK. NO UPDATES PLANNED. PREVIOUS
DISCUSSION BELOW STILL APPLIES.



.PREVIOUS DISCUSSION...330 PM MST...
HISTORIC RAIN AND FLOODING OCCURRED ACROSS PORTIONS OF THE PHOENIX
AREA TODAY. THE BIGGEST IMPACT WAS FELT ACROSS NORTHERN MARICOPA
COUNTY WHERE WIDESPREAD RAIN TOTALS OF 2 TO 5 INCHES WERE MEASURED.
A SECOND LINE OF STORMS DEVELOPED EARLY THIS AFTERNOON WHICH
PRODUCED AN ADDITIONAL HALF INCH TO ONE INCH OF RAIN ACROSS CENTRAL
AND NORTH PHOENIX. ELEVATED STREAMFLOWS WERE ALSO OBSERVED ACROSS
THE AGUA FRIA RIVER...SKUNK CREEK AND CAVE CREEK. THE AGUA FRIA
BRIEFLY CRESTED INTO THE MAJOR FLOOD CATEGORY BUT CONTINUES TO
RECEDE. MEANWHILE...CAVE CREEK REACHED A STAGE OF 12.75
FT...ECLIPSING THE PREVIOUS RECORD OF 12.1 FT FROM THE RAIN EVENT
IN JANUARY 2010.

LATEST WV IMAGERY SHOWS DRIER AIR WORKING ITS WAY INTO SOUTHWESTERN
AZ ASSOCIATED WITH THE CYCLONIC FLOW AROUND THE CLOSED LOW ALONG THE
CENTRAL CA COAST. DEWPOINTS CONTINUE TO DROP MAINLY WEST OF MARICOPA
COUNTY...THOUGH EVEN THE GPS-IPW AT TEMPE HAS DROPPED TO 1.6 INCHES.
NEVERTHELESS....SHOWERS HAVE REDEVELOPED ACROSS THE FAVORED HIGHER
TERRAIN AREAS OF EASTERN LA PAZ AND NORTHERN MARICOPA COUNTY. LATEST
MESOANALYSIS SHOWS WIDESPREAD CAPES ABOVE 500 J/KG WITH MINIMAL
INHIBITION STRETCHING FROM EASTERN RIVERSIDE COUNTY TO EASTERN AZ.
LATEST GLOBAL AND CONVECTIVE ALLOWING GUIDANCE SUGGESTS THE MOST
FAVORED AREA FOR ADDITIONAL STORMS WILL BE ACROSS NORTHWESTERN
MARICOPA COUNTY WHERE THE EXISTING INSTABILITY IS JUXTAPOSED WITH
STRONGER THAN NORMAL DEEP LAYER SHEAR. SHOWERS AND THUNDERSTORMS
WILL DISSIPATE THIS EVENING AS CONDITIONS STABILIZE RAPIDLY.

&&

.PREVIOUS DISCUSSION...
WEDNESDAY AND WEDNESDAY NIGHT...
A SIGNIFICANT REDUCTION IN SHOWER/THUNDERSTORM ACTIVITY IS EXPECTED
ON WEDNESDAY AND WEDNESDAY NIGHT AS PWATS FALL INTO THE 1.25-150
INCH RANGE AS SOUTHWESTERLY FLOW ALOFT STRENGTHENS OVER THE REGION
AHEAD OF THE MAIN UPPER LOW CENTER. STILL...ISOLATED TO SCATTERED
STORMS CAN BE EXPECTED...WITH THE BEST CHANCES FOR STORMS BEING OVER
THE HIGHER TERRAIN NORTH AND EAST OF PHOENIX AS STRONGER WINDS ALOFT
INCREASES BULK SHEAR VALUES OVER THE REGION.

THURSDAY AND FRIDAY...
THE LIKELIHOOD OF A SECOND HEAVY RAIN EVENT ON THURSDAY/FRIDAY NOW
LOOKS TO BE SIGNIFICANTLY LESS...SINCE LATEST MODELS RUNS ARE NOW
SHOWING MUCH LESS TROPICAL MOISTURE...FROM TROPICAL STORM
LOWELL...BEING PULLED NORTHEASTWARD INTO THE REGION. THUS...HAVE
REDUCED POPS SOMEWHAT ON THU/FRI...BUT STILL KEEPING THINGS
BROADBRUSHED A BIT...SINCE THE EURO CONTINUES TO BE SLOWER WITH THE
MOVEMENT OF THE UPPER LOW CENTER...TAKING IT ACROSS AZ ON
FRIDAY...WHILE THE FASTER GFS CONTINUES TO MOVE IT THROUGH ON
THURSDAY.

SATURDAY THROUGH TUESDAY...
THE COMBINATION OF A DRIER WESTERLY FLOW ALONG WITH RIDGING ALOFT
WILL LIKELY KEEP CHANCES FOR THUNDERSTORM ACTIVITY AT CLIMO...OR
BELOW LEVELS DURING THIS PERIOD. HOWEVER...IT STILL APPEARS THAT
THERE WILL BE ENOUGH RESIDUAL MOISTURE AROUND TO KEEP US FROM
ELIMINATING CHANCES FOR POPS ENTIRELY AT THIS POINT...WITH
TEMPERATURES RETURNING TO NEAR...OR SLIGHTLY ABOVE NORMAL VALUES.

&&

.AVIATION...
SOUTH-CENTRAL ARIZONA INCLUDING KPHX...KIWA...AND KSDL...

CLEARING SKIES AND IMPROVING CIGS THIS AFTERNOON AND EVENING AS
DRIER AIR BEGINS TO OVERSPREAD THE AREA. SCT CLOUD DECKS GENERALLY
AOA 6000FT...OCCASIONALLY BKN AROUND 10-12KFT OVERNIGHT INTO
WEDNESDAY MORNING. WINDS SHOULD FAVOR NORTHWEST AT TERMINALS UNTIL
02Z...THEN BECOME EASTERLY OVERNIGHT.

SOUTHWEST ARIZONA AND SOUTHEAST CALIFORNIA INCLUDING KIPL AND KBLH...

MOSTLY CLEAR SKIES THIS EVENING AND OVERNIGHT...WINDS LIGHT 12KT OR
LESS AT TERMINALS...FAVORING SOUTHWEST-WEST OVERNIGHT INTO WEDNESDAY
MORNING.

AVIATION DISCUSSION NOT UPDATED FOR AMENDED TAFS.

&&

.FIRE WEATHER...
THURSDAY THROUGH MONDAY...
A SLIGHT CHANCE OF AFTERNOON AND EVENING THUNDERSTORMS WILL CONTINUE
MAINLY EAST OF THE LOWER COLORADO RIVER VALLEY ON THURSDAY WITH A
CHANCE ACROSS THE HIGHER TERRAIN EAST OF PHOENIX. LITTLE CHANGE IS
EXPECTED FRIDAY. HIGH TEMPERATURES BOTH DAYS WILL STAY BELOW
SEASONAL NORMALS...WITH COOLER DESERTS FALLING INTO THE 90S.
HUMIDITY LEVELS WILL STAY QUITE ELEVATED WITH MOST OF THE DESERTS
RECORDING MINIMUM RH VALUES BETWEEN 20 AND 30 PERCENT. A STEADY
SOUTHWEST FLOW ALOFT WILL LEAD TO GRADUAL DRYING AND WARMING
CONDITIONS OVER THE WEEKEND AND INTO EARLY NEXT WEEK. BY SUNDAY
THERE WILL BE JUST A SLIGHT CHANCE OF AFTERNOON AND EVENING
THUNDERSTORMS ACROSS THE HIGHER TERRAIN EAST OF PHOENIX WITH PARTLY
TO MOSTLY SUNNY SKIES EXPECTED ELSEWHERE. DESPITE THE DRYING
TREND...MINIMUM RH VALUES WILL STAY ON THE ELEVATED SIDE AND SHOULD
MOSTLY RANGE FROM 15 TO 25 PERCENT. NO STRONG WINDS ARE EXPECTED
THROUGH THE PERIOD...MAINLY NORMAL DIURNAL WINDS FAVORING THE SOUTH
TO SOUTHWEST LESS THAN 15 MPH.

&&

.PSR WATCHES/WARNINGS/ADVISORIES...

AZ...NONE.

CA...NONE.

&&

$$

VISIT US ON FACEBOOK...TWITTER...AND AT WEATHER.GOV/PHOENIX

DISCUSSION...VASQUEZ/PERCHA
AVIATION....VASQUEZ
FIRE WEATHER...CB










000
FXUS65 KPSR 192235
AFDPSR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PHOENIX AZ
330 PM MST TUE AUG 19 2014

.SYNOPSIS...
SCATTERED SHOWERS AND THUNDERSTORMS WILL REMAIN A THREAT THROUGH
THURSDAY AS AN AREA OF LOW PRESSURE MOVES TOWARDS THE DESERT
SOUTHWEST. DRIER AIR SPREADING IN FROM THE WEST WILL REDUCE
THUNDERSTORM ACTIVITY FROM THIS WEEKEND INTO EARLY NEXT WEEK. BELOW
NORMAL TEMPERATURES ARE FORECAST FROM TODAY THROUGH FRIDAY...WARMING
THIS WEEKEND.

&&

.DISCUSSION...
HISTORIC RAIN AND FLOODING OCCURRED ACROSS PORTIONS OF THE PHOENIX
AREA TODAY. THE BIGGEST IMPACT WAS FELT ACROSS NORTHERN MARICOPA
COUNTY WHERE WIDESPREAD RAIN TOTALS OF 2 TO 5 INCHES WERE MEASURED.
A SECOND LINE OF STORMS DEVELOPED EARLY THIS AFTERNOON WHICH
PRODUCED AN ADDITIONAL HALF INCH TO ONE INCH OF RAIN ACROSS CENTRAL
AND NORTH PHOENIX. ELEVATED STREAMFLOWS WERE ALSO OBSERVED ACROSS
THE AGUA FRIA RIVER...SKUNK CREEK AND CAVE CREEK. THE AGUA FRIA
BRIEFLY CRESTED INTO THE MAJOR FLOOD CATEGORY BUT CONTINUES TO
RECEDE. MEANWHILE...CAVE CREEK REACHED A STAGE OF 12.75
FT...ECLIPSING THE PREVIOUS RECORD OF 12.1 FT FROM THE RAIN EVENT
IN JANUARY 2010.

LATEST WV IMAGERY SHOWS DRIER AIR WORKING ITS WAY INTO SOUTHWESTERN
AZ ASSOCIATED WITH THE CYCLONIC FLOW AROUND THE CLOSED LOW ALONG THE
CENTRAL CA COAST. DEWPOINTS CONTINUE TO DROP MAINLY WEST OF MARICOPA
COUNTY...THOUGH EVEN THE GPS-IPW AT TEMPE HAS DROPPED TO 1.6 INCHES.
NEVERTHELESS....SHOWERS HAVE REDEVELOPED ACROSS THE FAVORED HIGHER
TERRAIN AREAS OF EASTERN LA PAZ AND NORTHERN MARICOPA COUNTY. LATEST
MESOANALYSIS SHOWS WIDESPREAD CAPES ABOVE 500 J/KG WITH MINIMAL
INHIBITION STRETCHING FROM EASTERN RIVERSIDE COUNTY TO EASTERN AZ.
LATEST GLOBAL AND CONVECTIVE ALLOWING GUIDANCE SUGGESTS THE MOST
FAVORED AREA FOR ADDITIONAL STORMS WILL BE ACROSS NORTHWESTERN
MARICOPA COUNTY WHERE THE EXISTING INSTABILITY IS JUXTAPOSED WITH
STRONGER THAN NORMAL DEEP LAYER SHEAR. SHOWERS AND THUNDERSTORMS
WILL DISSIPATE THIS EVENING AS CONDITIONS STABILIZE RAPIDLY.

&&

.PREVIOUS DISCUSSION...
WEDNESDAY AND WEDNESDAY NIGHT...
A SIGNIFICANT REDUCTION IN SHOWER/THUNDERSTORM ACTIVITY IS EXPECTED
ON WEDNESDAY AND WEDNESDAY NIGHT AS PWATS FALL INTO THE 1.25-150
INCH RANGE AS SOUTHWESTERLY FLOW ALOFT STRENGTHENS OVER THE REGION
AHEAD OF THE MAIN UPPER LOW CENTER. STILL...ISOLATED TO SCATTERED
STORMS CAN BE EXPECTED...WITH THE BEST CHANCES FOR STORMS BEING OVER
THE HIGHER TERRAIN NORTH AND EAST OF PHOENIX AS STRONGER WINDS ALOFT
INCREASES BULK SHEAR VALUES OVER THE REGION.

THURSDAY AND FRIDAY...
THE LIKELIHOOD OF A SECOND HEAVY RAIN EVENT ON THURSDAY/FRIDAY NOW
LOOKS TO BE SIGNIFICANTLY LESS...SINCE LATEST MODELS RUNS ARE NOW
SHOWING MUCH LESS TROPICAL MOISTURE...FROM TROPICAL STORM
LOWELL...BEING PULLED NORTHEASTWARD INTO THE REGION. THUS...HAVE
REDUCED POPS SOMEWHAT ON THU/FRI...BUT STILL KEEPING THINGS
BROADBRUSHED A BIT...SINCE THE EURO CONTINUES TO BE SLOWER WITH THE
MOVEMENT OF THE UPPER LOW CENTER...TAKING IT ACROSS AZ ON
FRIDAY...WHILE THE FASTER GFS CONTINUES TO MOVE IT THROUGH ON
THURSDAY.

SATURDAY THROUGH TUESDAY...
THE COMBINATION OF A DRIER WESTERLY FLOW ALONG WITH RIDGING ALOFT
WILL LIKELY KEEP CHANCES FOR THUNDERSTORM ACTIVITY AT CLIMO...OR
BELOW LEVELS DURING THIS PERIOD. HOWEVER...IT STILL APPEARS THAT
THERE WILL BE ENOUGH RESIDUAL MOISTURE AROUND TO KEEP US FROM
ELIMINATING CHANCES FOR POPS ENTIRELY AT THIS POINT...WITH
TEMPERATURES RETURNING TO NEAR...OR SLIGHTLY ABOVE NORMAL VALUES.

&&

.AVIATION...
SOUTH-CENTRAL ARIZONA INCLUDING KPHX...KIWA...AND KSDL...

CLEARING SKIES AND IMPROVING CIGS THIS AFTERNOON AND EVENING AS
DRIER AIR BEGINS TO OVERSPREAD THE AREA. SCT CLOUD DECKS GENERALLY
AOA 6000FT...OCCASIONALLY BKN AROUND 10-12KFT OVERNIGHT INTO
WEDNESDAY MORNING. WINDS SHOULD FAVOR NORTHWEST AT TERMINALS UNTIL
02Z...THEN BECOME EASTERLY OVERNIGHT.

SOUTHWEST ARIZONA AND SOUTHEAST CALIFORNIA INCLUDING KIPL AND KBLH...

MOSTLY CLEAR SKIES THIS EVENING AND OVERNIGHT...WINDS LIGHT 12KT OR
LESS AT TERMINALS...FAVORING SOUTHWEST-WEST OVERNIGHT INTO WEDNESDAY
MORNING.

AVIATION DISCUSSION NOT UPDATED FOR AMENDED TAFS.

&&

.FIRE WEATHER...
THURSDAY THROUGH MONDAY...
A SLIGHT CHANCE OF AFTERNOON AND EVENING THUNDERSTORMS WILL CONTINUE
MAINLY EAST OF THE LOWER COLORADO RIVER VALLEY ON THURSDAY WITH A
CHANCE ACROSS THE HIGHER TERRAIN EAST OF PHOENIX. LITTLE CHANGE IS
EXPECTED FRIDAY. HIGH TEMPERATURES BOTH DAYS WILL STAY BELOW
SEASONAL NORMALS...WITH COOLER DESERTS FALLING INTO THE 90S.
HUMIDITY LEVELS WILL STAY QUITE ELEVATED WITH MOST OF THE DESERTS
RECORDING MINIMUM RH VALUES BETWEEN 20 AND 30 PERCENT. A STEADY
SOUTHWEST FLOW ALOFT WILL LEAD TO GRADUAL DRYING AND WARMING
CONDITIONS OVER THE WEEKEND AND INTO EARLY NEXT WEEK. BY SUNDAY
THERE WILL BE JUST A SLIGHT CHANCE OF AFTERNOON AND EVENING
THUNDERSTORMS ACROSS THE HIGHER TERRAIN EAST OF PHOENIX WITH PARTLY
TO MOSTLY SUNNY SKIES EXPECTED ELSEWHERE. DESPITE THE DRYING
TREND...MINIMUM RH VALUES WILL STAY ON THE ELEVATED SIDE AND SHOULD
MOSTLY RANGE FROM 15 TO 25 PERCENT. NO STRONG WINDS ARE EXPECTED
THROUGH THE PERIOD...MAINLY NORMAL DIURNAL WINDS FAVORING THE SOUTH
TO SOUTHWEST LESS THAN 15 MPH.

&&

.PSR WATCHES/WARNINGS/ADVISORIES...

AZ...FLASH FLOOD WATCH UNTIL 6 PM MST THIS EVENING AZZ022>024.

CA...NONE.

&&

$$

VISIT US ON FACEBOOK...TWITTER...AND AT WEATHER.GOV/PHOENIX

DISCUSSION...HIRSCH
PREVIOUS DISCUSSION...PERCHA
AVIATION....MEYERS
FIRE WEATHER...CB






000
FXUS65 KPSR 192235
AFDPSR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PHOENIX AZ
330 PM MST TUE AUG 19 2014

.SYNOPSIS...
SCATTERED SHOWERS AND THUNDERSTORMS WILL REMAIN A THREAT THROUGH
THURSDAY AS AN AREA OF LOW PRESSURE MOVES TOWARDS THE DESERT
SOUTHWEST. DRIER AIR SPREADING IN FROM THE WEST WILL REDUCE
THUNDERSTORM ACTIVITY FROM THIS WEEKEND INTO EARLY NEXT WEEK. BELOW
NORMAL TEMPERATURES ARE FORECAST FROM TODAY THROUGH FRIDAY...WARMING
THIS WEEKEND.

&&

.DISCUSSION...
HISTORIC RAIN AND FLOODING OCCURRED ACROSS PORTIONS OF THE PHOENIX
AREA TODAY. THE BIGGEST IMPACT WAS FELT ACROSS NORTHERN MARICOPA
COUNTY WHERE WIDESPREAD RAIN TOTALS OF 2 TO 5 INCHES WERE MEASURED.
A SECOND LINE OF STORMS DEVELOPED EARLY THIS AFTERNOON WHICH
PRODUCED AN ADDITIONAL HALF INCH TO ONE INCH OF RAIN ACROSS CENTRAL
AND NORTH PHOENIX. ELEVATED STREAMFLOWS WERE ALSO OBSERVED ACROSS
THE AGUA FRIA RIVER...SKUNK CREEK AND CAVE CREEK. THE AGUA FRIA
BRIEFLY CRESTED INTO THE MAJOR FLOOD CATEGORY BUT CONTINUES TO
RECEDE. MEANWHILE...CAVE CREEK REACHED A STAGE OF 12.75
FT...ECLIPSING THE PREVIOUS RECORD OF 12.1 FT FROM THE RAIN EVENT
IN JANUARY 2010.

LATEST WV IMAGERY SHOWS DRIER AIR WORKING ITS WAY INTO SOUTHWESTERN
AZ ASSOCIATED WITH THE CYCLONIC FLOW AROUND THE CLOSED LOW ALONG THE
CENTRAL CA COAST. DEWPOINTS CONTINUE TO DROP MAINLY WEST OF MARICOPA
COUNTY...THOUGH EVEN THE GPS-IPW AT TEMPE HAS DROPPED TO 1.6 INCHES.
NEVERTHELESS....SHOWERS HAVE REDEVELOPED ACROSS THE FAVORED HIGHER
TERRAIN AREAS OF EASTERN LA PAZ AND NORTHERN MARICOPA COUNTY. LATEST
MESOANALYSIS SHOWS WIDESPREAD CAPES ABOVE 500 J/KG WITH MINIMAL
INHIBITION STRETCHING FROM EASTERN RIVERSIDE COUNTY TO EASTERN AZ.
LATEST GLOBAL AND CONVECTIVE ALLOWING GUIDANCE SUGGESTS THE MOST
FAVORED AREA FOR ADDITIONAL STORMS WILL BE ACROSS NORTHWESTERN
MARICOPA COUNTY WHERE THE EXISTING INSTABILITY IS JUXTAPOSED WITH
STRONGER THAN NORMAL DEEP LAYER SHEAR. SHOWERS AND THUNDERSTORMS
WILL DISSIPATE THIS EVENING AS CONDITIONS STABILIZE RAPIDLY.

&&

.PREVIOUS DISCUSSION...
WEDNESDAY AND WEDNESDAY NIGHT...
A SIGNIFICANT REDUCTION IN SHOWER/THUNDERSTORM ACTIVITY IS EXPECTED
ON WEDNESDAY AND WEDNESDAY NIGHT AS PWATS FALL INTO THE 1.25-150
INCH RANGE AS SOUTHWESTERLY FLOW ALOFT STRENGTHENS OVER THE REGION
AHEAD OF THE MAIN UPPER LOW CENTER. STILL...ISOLATED TO SCATTERED
STORMS CAN BE EXPECTED...WITH THE BEST CHANCES FOR STORMS BEING OVER
THE HIGHER TERRAIN NORTH AND EAST OF PHOENIX AS STRONGER WINDS ALOFT
INCREASES BULK SHEAR VALUES OVER THE REGION.

THURSDAY AND FRIDAY...
THE LIKELIHOOD OF A SECOND HEAVY RAIN EVENT ON THURSDAY/FRIDAY NOW
LOOKS TO BE SIGNIFICANTLY LESS...SINCE LATEST MODELS RUNS ARE NOW
SHOWING MUCH LESS TROPICAL MOISTURE...FROM TROPICAL STORM
LOWELL...BEING PULLED NORTHEASTWARD INTO THE REGION. THUS...HAVE
REDUCED POPS SOMEWHAT ON THU/FRI...BUT STILL KEEPING THINGS
BROADBRUSHED A BIT...SINCE THE EURO CONTINUES TO BE SLOWER WITH THE
MOVEMENT OF THE UPPER LOW CENTER...TAKING IT ACROSS AZ ON
FRIDAY...WHILE THE FASTER GFS CONTINUES TO MOVE IT THROUGH ON
THURSDAY.

SATURDAY THROUGH TUESDAY...
THE COMBINATION OF A DRIER WESTERLY FLOW ALONG WITH RIDGING ALOFT
WILL LIKELY KEEP CHANCES FOR THUNDERSTORM ACTIVITY AT CLIMO...OR
BELOW LEVELS DURING THIS PERIOD. HOWEVER...IT STILL APPEARS THAT
THERE WILL BE ENOUGH RESIDUAL MOISTURE AROUND TO KEEP US FROM
ELIMINATING CHANCES FOR POPS ENTIRELY AT THIS POINT...WITH
TEMPERATURES RETURNING TO NEAR...OR SLIGHTLY ABOVE NORMAL VALUES.

&&

.AVIATION...
SOUTH-CENTRAL ARIZONA INCLUDING KPHX...KIWA...AND KSDL...

CLEARING SKIES AND IMPROVING CIGS THIS AFTERNOON AND EVENING AS
DRIER AIR BEGINS TO OVERSPREAD THE AREA. SCT CLOUD DECKS GENERALLY
AOA 6000FT...OCCASIONALLY BKN AROUND 10-12KFT OVERNIGHT INTO
WEDNESDAY MORNING. WINDS SHOULD FAVOR NORTHWEST AT TERMINALS UNTIL
02Z...THEN BECOME EASTERLY OVERNIGHT.

SOUTHWEST ARIZONA AND SOUTHEAST CALIFORNIA INCLUDING KIPL AND KBLH...

MOSTLY CLEAR SKIES THIS EVENING AND OVERNIGHT...WINDS LIGHT 12KT OR
LESS AT TERMINALS...FAVORING SOUTHWEST-WEST OVERNIGHT INTO WEDNESDAY
MORNING.

AVIATION DISCUSSION NOT UPDATED FOR AMENDED TAFS.

&&

.FIRE WEATHER...
THURSDAY THROUGH MONDAY...
A SLIGHT CHANCE OF AFTERNOON AND EVENING THUNDERSTORMS WILL CONTINUE
MAINLY EAST OF THE LOWER COLORADO RIVER VALLEY ON THURSDAY WITH A
CHANCE ACROSS THE HIGHER TERRAIN EAST OF PHOENIX. LITTLE CHANGE IS
EXPECTED FRIDAY. HIGH TEMPERATURES BOTH DAYS WILL STAY BELOW
SEASONAL NORMALS...WITH COOLER DESERTS FALLING INTO THE 90S.
HUMIDITY LEVELS WILL STAY QUITE ELEVATED WITH MOST OF THE DESERTS
RECORDING MINIMUM RH VALUES BETWEEN 20 AND 30 PERCENT. A STEADY
SOUTHWEST FLOW ALOFT WILL LEAD TO GRADUAL DRYING AND WARMING
CONDITIONS OVER THE WEEKEND AND INTO EARLY NEXT WEEK. BY SUNDAY
THERE WILL BE JUST A SLIGHT CHANCE OF AFTERNOON AND EVENING
THUNDERSTORMS ACROSS THE HIGHER TERRAIN EAST OF PHOENIX WITH PARTLY
TO MOSTLY SUNNY SKIES EXPECTED ELSEWHERE. DESPITE THE DRYING
TREND...MINIMUM RH VALUES WILL STAY ON THE ELEVATED SIDE AND SHOULD
MOSTLY RANGE FROM 15 TO 25 PERCENT. NO STRONG WINDS ARE EXPECTED
THROUGH THE PERIOD...MAINLY NORMAL DIURNAL WINDS FAVORING THE SOUTH
TO SOUTHWEST LESS THAN 15 MPH.

&&

.PSR WATCHES/WARNINGS/ADVISORIES...

AZ...FLASH FLOOD WATCH UNTIL 6 PM MST THIS EVENING AZZ022>024.

CA...NONE.

&&

$$

VISIT US ON FACEBOOK...TWITTER...AND AT WEATHER.GOV/PHOENIX

DISCUSSION...HIRSCH
PREVIOUS DISCUSSION...PERCHA
AVIATION....MEYERS
FIRE WEATHER...CB







000
FXUS65 KPSR 191559
AFDPSR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PHOENIX AZ
900 AM MST TUE AUG 19 2014

.SYNOPSIS...
AN EARLY SEASON PACIFIC LOW PRESSURE SYSTEM APPROACHING THE AREA
FROM THE WEST IS EXPECTED TO PRODUCE WIDESPREAD SHOWER AND
THUNDERSTORM ACTIVITY THROUGH THE DAY TODAY...WITH LESSER CHANCES
FOR CONVECTIVE ACTIVITY THROUGH FRIDAY AS THE LOW CENTER MOVES
SLOWLY EASTWARD ACROSS THE REGION. DRIER AIR SPREADING IN FROM THE
WEST WILL REDUCE THUNDERSTORM ACTIVITY FROM THIS WEEKEND INTO EARLY
NEXT WEEK. BELOW NORMAL TEMPERATURES ARE FORECAST FROM TODAY THROUGH
FRIDAY...WARMING THIS WEEKEND.

&&

.DISCUSSION...
MCS DEVELOPED THIS MORNING ACROSS NORTHERN AND EASTERN MARICOPA
COUNTY...DROPPING HEAVY RAIN ACROSS PORTIONS OF THE PHOENIX AREA.
LOCATIONS ACROSS THE NORTH VALLEY GENERALLY RECEIVED BETWEEN A
QUARTER AND THREE QUARTERS OF AN INCH OF RAIN. HOWEVER...FCDMC
GAGES HAVE RECORDED AS MUCH AS 1 TO 3 INCHES OF RAIN FURTHER NORTH
AND EAST. THIS HAS PRODUCED AREAS OF URBAN FLOODING ALONG WITH
ELEVATED FLOW IN WASHES AND CREEKS INCLUDING CAVE CREEK AND THE AGUA
FRIA RIVER. A FLASH FLOOD WATCH WAS ISSUED EARLIER THIS MORNING AND
CONTINUES UNTIL NOON. A FLASH FLOOD WARNING ALSO REMAINS IN EFFECT
FOR MUCH OF NORTHERN MARICOPA COUNTY.

LATEST NUMERICAL GUIDANCE SUGGESTS A GENERAL DRYING TREND WILL TAKE
PLACE TODAY. HOWEVER...THE LOWER LEVELS ARE EXCEPTIONALLY MOIST WITH
DEWPOINTS IN THE MID 70S AND CONDITIONS REMAIN UNSTABLE FROM PHOENIX
WESTWARD TOWARDS THE CO RIVER VALLEY WITH MLCAPE > 1000 J/KG.
BACKBUILDING SHOWERS HAVE DEVELOPED ACROSS NORTHWESTERN MARICOPA
COUNTY AND ADDITIONAL ISOLATED CELLS ARE EXPECTED INTO LA PAZ
COUNTY. UPSLOPE FLOW WILL THEN SUPPORT ADDITIONAL ISOLATED SHOWERS
FURTHER EAST ACROSS MARICOPA AND GILA COUNTIES THIS AFTERNOON.
FORECAST WILL BE UPDATED TO REFINE THE POPS FOR THE AFOREMENTIONED
AREAS.

&&

.PREVIOUS DISCUSSION...
WEDNESDAY AND WEDNESDAY NIGHT...
A SIGNIFICANT REDUCTION IN SHOWER/THUNDERSTORM ACTIVITY IS EXPECTED
ON WEDNESDAY AND WEDNESDAY NIGHT AS PWATS FALL INTO THE 1.25-150
INCH RANGE AS SOUTHWESTERLY FLOW ALOFT STRENGTHENS OVER THE REGION
AHEAD OF THE MAIN UPPER LOW CENTER. STILL...ISOLATED TO SCATTERED
STORMS CAN BE EXPECTED...WITH THE BEST CHANCES FOR STORMS BEING OVER
THE HIGHER TERRAIN NORTH AND EAST OF PHOENIX AS STRONGER WINDS ALOFT
INCREASES BULK SHEAR VALUES OVER THE REGION.

THURSDAY AND FRIDAY...
THE LIKELIHOOD OF A SECOND HEAVY RAIN EVENT ON THURSDAY/FRIDAY NOW
LOOKS TO BE SIGNIFICANTLY LESS...SINCE LATEST MODELS RUNS ARE NOW
SHOWING MUCH LESS TROPICAL MOISTURE...FROM TROPICAL STORM
LOWELL...BEING PULLED NORTHEASTWARD INTO THE REGION. THUS...HAVE
REDUCED POPS SOMEWHAT ON THU/FRI...BUT STILL KEEPING THINGS
BROADBRUSHED A BIT...SINCE THE EURO CONTINUES TO BE SLOWER WITH THE
MOVEMENT OF THE UPPER LOW CENTER...TAKING IT ACROSS AZ ON
FRIDAY...WHILE THE FASTER GFS CONTINUES TO MOVE IT THROUGH ON
THURSDAY.

SATURDAY THROUGH TUESDAY...
THE COMBINATION OF A DRIER WESTERLY FLOW ALONG WITH RIDGING ALOFT
WILL LIKELY KEEP CHANCES FOR THUNDERSTORM ACTIVITY AT CLIMO...OR
BELOW LEVELS DURING THIS PERIOD. HOWEVER...IT STILL APPEARS THAT
THERE WILL BE ENOUGH RESIDUAL MOISTURE AROUND TO KEEP US FROM
ELIMINATING CHANCES FOR POPS ENTIRELY AT THIS POINT...WITH
TEMPERATURES RETURNING TO NEAR...OR SLIGHTLY ABOVE NORMAL VALUES.

&&

.AVIATION...
SOUTH-CENTRAL ARIZONA INCLUDING KPHX...KIWA...KSDL...
AS UPPER TROF APPROACHES FROM THE WEST AND MONSOON MOISTURE
INCREASES...STILL EXPECT SHOWERS AND THUNDERSTORMS TO INCREASE THIS
MORNING...BECOMING NUMEROUS BY 14-15Z. WILL KEEP MENTION OF
THUNDER...AS VCTS...IN TAFS THRU ABOUT 16Z...THEN FIGURE RAIN WILL
HAVE COOLED AND STABILIZED BOUNDARY LAYER ENOUGH THAT WE SHOULD BE
IN A MORE SHOWERY REGIME THAT WILL CONTINUE INTO THE AFTERNOON.
DEPENDING UPON HOW MUCH SUNSHINE IS SEEN THIS AFTERNOON THERE MAY BE
ANOTHER ROUND OF THUNDERSTORMS TO DEAL WITH AT THE TERMINALS. WILL
WAIT FOR LATER TO SEE HOW THAT PLAYS OUT. OTHERWISE WINDS SHOULD
FAVOR THE SOUTH TO SOUTHEAST THIS MORNING...TRANSITIONING MORE
TOWARDS SOUTHWEST IN THE AFTERNOON WITH SPEEDS MOSTLY AOB 12KT.

NOTE...IF SHOWERS/STORMS CONTINUE TO TAKE THEIR TIME
DEVELOPING...THE TAFS WILL BE OVERPLAYING THE WEATHER AND WILL NEED
TO BE UPDATED TO PUSH BACK THE PRECIP ONSET.

SOUTHWEST ARIZONA AND SOUTHEAST CALIFORNIA INCLUDING KIPL AND KBLH...
EXPECT SHOWERS/STORMS TO MOSTLY STAY EAST OF KIPL TODAY...WITH
COVERAGE AT KBLH TO BE MORE ON THE ISOLATED SIDE. WITH UPPER JET
APPROACHING...THERE WILL BE A THREAT FOR AFTN/EARLY EVE THUNDER AT
THE TERMINAL AND THUS WILL KEEP VCTS IN THE KBLH TAF. WINDS TO FAVOR
THE SOUTH AT KBLH...BECOMING GUSTY THIS AFTERNOON WITH SPEEDS AOB
20KT. AT KIPL...EXPECT MID/UPPER CLOUD DECKS TO SCATTER OUT BY 18Z
WITH WINDS TO SHIFT TOWARDS THE SOUTHWEST...BECOMING LOCALLY BREEZY
FROM THE WEST EARLY THIS EVENING.

AVIATION DISCUSSION NOT UPDATED FOR AMENDED TAFS.

&&

.FIRE WEATHER...
THURSDAY THROUGH MONDAY...
A SLIGHT CHANCE OF AFTERNOON AND EVENING THUNDERSTORMS WILL CONTINUE
MAINLY EAST OF THE LOWER COLORADO RIVER VALLEY ON THURSDAY WITH A
CHANCE ACROSS THE HIGHER TERRAIN EAST OF PHOENIX. LITTLE CHANGE IS
EXPECTED FRIDAY. HIGH TEMPERATURES BOTH DAYS WILL STAY BELOW
SEASONAL NORMALS...WITH COOLER DESERTS FALLING INTO THE 90S.
HUMIDITY LEVELS WILL STAY QUITE ELEVATED WITH MOST OF THE DESERTS
RECORDING MINIMUM RH VALUES BETWEEN 20 AND 30 PERCENT. A STEADY
SOUTHWEST FLOW ALOFT WILL LEAD TO GRADUAL DRYING AND WARMING
CONDITIONS OVER THE WEEKEND AND INTO EARLY NEXT WEEK. BY SUNDAY
THERE WILL BE JUST A SLIGHT CHANCE OF AFTERNOON AND EVENING
THUNDERSTORMS ACROSS THE HIGHER TERRAIN EAST OF PHOENIX WITH PARTLY
TO MOSTLY SUNNY SKIES EXPECTED ELSEWHERE. DESPITE THE DRYING
TREND...MINIMUM RH VALUES WILL STAY ON THE ELEVATED SIDE AND SHOULD
MOSTLY RANGE FROM 15 TO 25 PERCENT. NO STRONG WINDS ARE EXPECTED
THROUGH THE PERIOD...MAINLY NORMAL DIURNAL WINDS FAVORING THE SOUTH
TO SOUTHWEST LESS THAN 15 MPH.

&&

.PSR WATCHES/WARNINGS/ADVISORIES...

AZ...NONE.

CA...NONE.

&&

$$

VISIT US ON FACEBOOK...TWITTER...AND AT WEATHER.GOV/PHOENIX

DISCUSSION...HIRSCH
PREVIOUS DISCUSSION...PERCHA
AVIATION....CB
FIRE WEATHER...CB







000
FXUS65 KPSR 191145 AAA
AFDPSR

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE PHOENIX AZ
445 AM MST TUE AUG 19 2014

.UPDATE...UPDATED AVIATION AND FIRE WEATHER DISCUSSIONS.

&&

.SYNOPSIS...
AN EARLY SEASON PACIFIC LOW PRESSURE SYSTEM APPROACHING THE AREA
FROM THE WEST IS EXPECTED TO PRODUCE WIDESPREAD SHOWER AND
THUNDERSTORM ACTIVITY THROUGH THE DAY TODAY...WITH LESSER CHANCES
FOR CONVECTIVE ACTIVITY THROUGH FRIDAY AS THE LOW CENTER MOVES
SLOWLY EASTWARD ACROSS THE REGION. DRIER AIR SPREADING IN FROM THE
WEST WILL REDUCE THUNDERSTORM ACTIVITY FROM THIS WEEKEND INTO EARLY
NEXT WEEK. BELOW NORMAL TEMPERATURES ARE FORECAST FROM TODAY THROUGH
FRIDAY...WARMING THIS WEEKEND.

&&

.DISCUSSION...
TODAY...
STORM COVERAGE SO FAR THIS EARLY MORNING CONTINUES TO BE BEEN VERY
LIMITED...WITH A FEW SHOWERS NOW BEGINNING TO DEVELOP ACROSS LA
PAZ...MARICOPA...AND SOUTHERN GILA COUNTY AT THIS HOUR. WE ARE STILL
EXPECTING WIDESPREAD SHOWER AND THUNDERSTORM ACTIVITY TO DEVELOP
THROUGH THE REST OF THIS MORNING AS THE UPPER LOW THAT IS NOW
LOCATED JUST OFF THE CENTRAL CA COAST CONTINUES TO APPROACH THE
REGION. THE LATEST NAM/GFS/EURO MODEL SUITES CONTINUE TO SHOW THAT
SHOWERS/THUNDERSTORMS WILL DEVELOP ACROSS SW AND SOUTH-CENTRAL AZ
THIS MORNING...MAINLY ACROSS LA PAZ AND MARICOPA/PINAL/GILA
COUNTIES. HOWEVER RAINFALL AMOUNTS SEEM TO BE A BIT LESS THAN WHAT
WAS DEPICTED ON EARLIER RUNS...LIKELY DUE TO PWATS PEAKING IN THE
1.80-1.90 INCH RANGE...DOWN A BIT FROM THE 2.00-2.10 INCH THAT WAS
BEING FORECASTED YESTERDAY...BUT MOISTURE/DYNAMICS STILL APPEAR TO
BE GOOD ENOUGH TO JUSTIFY TO CONTINUE THE FORECAST FOR LOCALLY HEAVY
RAINFALL AMOUNTS...WITH THE BEST CHANCE FOR HEAVY RAINS TO BE BEFORE
NOON ACROSS SOUTH-CENTRAL AZ...AS A WEAK SHORTWAVE MOVES
NORTHEASTWARD ACROSS THE REGION. RAINFALL CHANCES WILL LIKELY DROP
NOTICEABLY THIS AFTERNOON/EVENING AS DRIER AIR BEGINS TO FILTER IN
FROM THE WEST BEHIND THIS SHORTWAVE AND THE ATMOSPHERE
STABILIZES...BUT HEAVY RAINFALL WILL STILL BE A POSSIBILITY OVER THE
FAVORED UPSLOPE AREAS OF SOUTHERN GILA COUNTY INTO TONIGHT. ALL THIS
RAINFALL/CLOUDS IS EXPECTED TO KEEP OUR HIGHS TODAY WELL BELOW
NORMAL...WITH MOST SOUTH-CENTRAL AZ LOWER DESERT LOCATIONS REMAINING
IN THE 90S.

WEDNESDAY AND WEDNESDAY NIGHT...
A SIGNIFICANT REDUCTION IN SHOWER/THUNDERSTORM ACTIVITY IS EXPECTED
ON WEDNESDAY AND WEDNESDAY NIGHT AS PWATS FALL INTO THE 1.25-150
INCH RANGE AS SOUTHWESTERLY FLOW ALOFT STRENGTHENS OVER THE REGION
AHEAD OF THE MAIN UPPER LOW CENTER. STILL...ISOLATED TO SCATTERED
STORMS CAN BE EXPECTED...WITH THE BEST CHANCES FOR STORMS BEING OVER
THE HIGHER TERRAIN NORTH AND EAST OF PHOENIX AS STRONGER WINDS ALOFT
INCREASES BULK SHEAR VALUES OVER THE REGION.

THURSDAY AND FRIDAY...
THE LIKELIHOOD OF A SECOND HEAVY RAIN EVENT ON THURSDAY/FRIDAY NOW
LOOKS TO BE SIGNIFICANTLY LESS...SINCE LATEST MODELS RUNS ARE NOW
SHOWING MUCH LESS TROPICAL MOISTURE...FROM TROPICAL STORM
LOWELL...BEING PULLED NORTHEASTWARD INTO THE REGION. THUS...HAVE
REDUCED POPS SOMEWHAT ON THU/FRI...BUT STILL KEEPING THINGS
BROADBRUSHED A BIT...SINCE THE EURO CONTINUES TO BE SLOWER WITH THE
MOVEMENT OF THE UPPER LOW CENTER...TAKING IT ACROSS AZ ON
FRIDAY...WHILE THE FASTER GFS CONTINUES TO MOVE IT THROUGH ON
THURSDAY.

SATURDAY THROUGH TUESDAY...
THE COMBINATION OF A DRIER WESTERLY FLOW ALONG WITH RIDGING ALOFT
WILL LIKELY KEEP CHANCES FOR THUNDERSTORM ACTIVITY AT CLIMO...OR
BELOW LEVELS DURING THIS PERIOD. HOWEVER...IT STILL APPEARS THAT
THERE WILL BE ENOUGH RESIDUAL MOISTURE AROUND TO KEEP US FROM
ELIMINATING CHANCES FOR POPS ENTIRELY AT THIS POINT...WITH
TEMPERATURES RETURNING TO NEAR...OR SLIGHTLY ABOVE NORMAL VALUES.

&&

.AVIATION...
SOUTH-CENTRAL ARIZONA INCLUDING KPHX...KIWA...KSDL...
AS UPPER TROF APPROACHES FROM THE WEST AND MONSOON MOISTURE
INCREASES...STILL EXPECT SHOWERS AND THUNDERSTORMS TO INCREASE THIS
MORNING...BECOMING NUMEROUS BY 14-15Z. WILL KEEP MENTION OF
THUNDER...AS VCTS...IN TAFS THRU ABOUT 16Z...THEN FIGURE RAIN WILL
HAVE COOLED AND STABILIZED BOUNDARY LAYER ENOUGH THAT WE SHOULD BE
IN A MORE SHOWERY REGIME THAT WILL CONTINUE INTO THE AFTERNOON.
DEPENDING UPON HOW MUCH SUNSHINE IS SEEN THIS AFTERNOON THERE MAY BE
ANOTHER ROUND OF THUNDERSTORMS TO DEAL WITH AT THE TERMINALS. WILL
WAIT FOR LATER TO SEE HOW THAT PLAYS OUT. OTHERWISE WINDS SHOULD
FAVOR THE SOUTH TO SOUTHEAST THIS MORNING...TRANSITIONING MORE
TOWARDS SOUTHWEST IN THE AFTERNOON WITH SPEEDS MOSTLY AOB 12KT.

NOTE...IF SHOWERS/STORMS CONTINUE TO TAKE THEIR TIME
DEVELOPING...THE TAFS WILL BE OVERPLAYING THE WEATHER AND WILL NEED
TO BE UPDATED TO PUSH BACK THE PRECIP ONSET.

SOUTHWEST ARIZONA AND SOUTHEAST CALIFORNIA INCLUDING KIPL AND KBLH...
EXPECT SHOWERS/STORMS TO MOSTLY STAY EAST OF KIPL TODAY...WITH
COVERAGE AT KBLH TO BE MORE ON THE ISOLATED SIDE. WITH UPPER JET
APPROACHING...THERE WILL BE A THREAT FOR AFTN/EARLY EVE THUNDER AT
THE TERMINAL AND THUS WILL KEEP VCTS IN THE KBLH TAF. WINDS TO FAVOR
THE SOUTH AT KBLH...BECOMING GUSTY THIS AFTERNOON WITH SPEEDS AOB
20KT. AT KIPL...EXPECT MID/UPPER CLOUD DECKS TO SCATTER OUT BY 18Z
WITH WINDS TO SHIFT TOWARDS THE SOUTHWEST...BECOMING LOCALLY BREEZY
FROM THE WEST EARLY THIS EVENING.

AVIATION DISCUSSION NOT UPDATED FOR AMENDED TAFS.

&&

.FIRE WEATHER...
THURSDAY THROUGH MONDAY...
A SLIGHT CHANCE OF AFTERNOON AND EVENING THUNDERSTORMS WILL CONTINUE
MAINLY EAST OF THE LOWER COLORADO RIVER VALLEY ON THURSDAY WITH A
CHANCE ACROSS THE HIGHER TERRAIN EAST OF PHOENIX. LITTLE CHANGE IS
EXPECTED FRIDAY. HIGH TEMPERATURES BOTH DAYS WILL STAY BELOW
SEASONAL NORMALS...WITH COOLER DESERTS FALLING INTO THE 90S.
HUMIDITY LEVELS WILL STAY QUITE ELEVATED WITH MOST OF THE DESERTS
RECORDING MINIMUM RH VALUES BETWEEN 20 AND 30 PERCENT. A STEADY
SOUTHWEST FLOW ALOFT WILL LEAD TO GRADUAL DRYING AND WARMING
CONDITIONS OVER THE WEEKEND AND INTO EARLY NEXT WEEK. BY SUNDAY
THERE WILL BE JUST A SLIGHT CHANCE OF AFTERNOON AND EVENING
THUNDERSTORMS ACROSS THE HIGHER TERRAIN EAST OF PHOENIX WITH PARTLY
TO MOSTLY SUNNY SKIES EXPECTED ELSEWHERE. DESPITE THE DRYING
TREND...MINIMUM RH VALUES WILL STAY ON THE ELEVATED SIDE AND SHOULD
MOSTLY RANGE FROM 15 TO 25 PERCENT. NO STRONG WINDS ARE EXPECTED
THROUGH THE PERIOD...MAINLY NORMAL DIURNAL WINDS FAVORING THE SOUTH
TO SOUTHWEST LESS THAN 15 MPH.

&&

.PSR WATCHES/WARNINGS/ADVISORIES...

AZ...NONE.

CA...NONE.

&&

$$

VISIT US ON FACEBOOK...TWITTER...AND AT WEATHER.GOV/PHOENIX

DISCUSSION...PERCHA
AVIATION....CB
FIRE WEATHER...CB









000
FXUS65 KPSR 191145 AAA
AFDPSR

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE PHOENIX AZ
445 AM MST TUE AUG 19 2014

.UPDATE...UPDATED AVIATION AND FIRE WEATHER DISCUSSIONS.

&&

.SYNOPSIS...
AN EARLY SEASON PACIFIC LOW PRESSURE SYSTEM APPROACHING THE AREA
FROM THE WEST IS EXPECTED TO PRODUCE WIDESPREAD SHOWER AND
THUNDERSTORM ACTIVITY THROUGH THE DAY TODAY...WITH LESSER CHANCES
FOR CONVECTIVE ACTIVITY THROUGH FRIDAY AS THE LOW CENTER MOVES
SLOWLY EASTWARD ACROSS THE REGION. DRIER AIR SPREADING IN FROM THE
WEST WILL REDUCE THUNDERSTORM ACTIVITY FROM THIS WEEKEND INTO EARLY
NEXT WEEK. BELOW NORMAL TEMPERATURES ARE FORECAST FROM TODAY THROUGH
FRIDAY...WARMING THIS WEEKEND.

&&

.DISCUSSION...
TODAY...
STORM COVERAGE SO FAR THIS EARLY MORNING CONTINUES TO BE BEEN VERY
LIMITED...WITH A FEW SHOWERS NOW BEGINNING TO DEVELOP ACROSS LA
PAZ...MARICOPA...AND SOUTHERN GILA COUNTY AT THIS HOUR. WE ARE STILL
EXPECTING WIDESPREAD SHOWER AND THUNDERSTORM ACTIVITY TO DEVELOP
THROUGH THE REST OF THIS MORNING AS THE UPPER LOW THAT IS NOW
LOCATED JUST OFF THE CENTRAL CA COAST CONTINUES TO APPROACH THE
REGION. THE LATEST NAM/GFS/EURO MODEL SUITES CONTINUE TO SHOW THAT
SHOWERS/THUNDERSTORMS WILL DEVELOP ACROSS SW AND SOUTH-CENTRAL AZ
THIS MORNING...MAINLY ACROSS LA PAZ AND MARICOPA/PINAL/GILA
COUNTIES. HOWEVER RAINFALL AMOUNTS SEEM TO BE A BIT LESS THAN WHAT
WAS DEPICTED ON EARLIER RUNS...LIKELY DUE TO PWATS PEAKING IN THE
1.80-1.90 INCH RANGE...DOWN A BIT FROM THE 2.00-2.10 INCH THAT WAS
BEING FORECASTED YESTERDAY...BUT MOISTURE/DYNAMICS STILL APPEAR TO
BE GOOD ENOUGH TO JUSTIFY TO CONTINUE THE FORECAST FOR LOCALLY HEAVY
RAINFALL AMOUNTS...WITH THE BEST CHANCE FOR HEAVY RAINS TO BE BEFORE
NOON ACROSS SOUTH-CENTRAL AZ...AS A WEAK SHORTWAVE MOVES
NORTHEASTWARD ACROSS THE REGION. RAINFALL CHANCES WILL LIKELY DROP
NOTICEABLY THIS AFTERNOON/EVENING AS DRIER AIR BEGINS TO FILTER IN
FROM THE WEST BEHIND THIS SHORTWAVE AND THE ATMOSPHERE
STABILIZES...BUT HEAVY RAINFALL WILL STILL BE A POSSIBILITY OVER THE
FAVORED UPSLOPE AREAS OF SOUTHERN GILA COUNTY INTO TONIGHT. ALL THIS
RAINFALL/CLOUDS IS EXPECTED TO KEEP OUR HIGHS TODAY WELL BELOW
NORMAL...WITH MOST SOUTH-CENTRAL AZ LOWER DESERT LOCATIONS REMAINING
IN THE 90S.

WEDNESDAY AND WEDNESDAY NIGHT...
A SIGNIFICANT REDUCTION IN SHOWER/THUNDERSTORM ACTIVITY IS EXPECTED
ON WEDNESDAY AND WEDNESDAY NIGHT AS PWATS FALL INTO THE 1.25-150
INCH RANGE AS SOUTHWESTERLY FLOW ALOFT STRENGTHENS OVER THE REGION
AHEAD OF THE MAIN UPPER LOW CENTER. STILL...ISOLATED TO SCATTERED
STORMS CAN BE EXPECTED...WITH THE BEST CHANCES FOR STORMS BEING OVER
THE HIGHER TERRAIN NORTH AND EAST OF PHOENIX AS STRONGER WINDS ALOFT
INCREASES BULK SHEAR VALUES OVER THE REGION.

THURSDAY AND FRIDAY...
THE LIKELIHOOD OF A SECOND HEAVY RAIN EVENT ON THURSDAY/FRIDAY NOW
LOOKS TO BE SIGNIFICANTLY LESS...SINCE LATEST MODELS RUNS ARE NOW
SHOWING MUCH LESS TROPICAL MOISTURE...FROM TROPICAL STORM
LOWELL...BEING PULLED NORTHEASTWARD INTO THE REGION. THUS...HAVE
REDUCED POPS SOMEWHAT ON THU/FRI...BUT STILL KEEPING THINGS
BROADBRUSHED A BIT...SINCE THE EURO CONTINUES TO BE SLOWER WITH THE
MOVEMENT OF THE UPPER LOW CENTER...TAKING IT ACROSS AZ ON
FRIDAY...WHILE THE FASTER GFS CONTINUES TO MOVE IT THROUGH ON
THURSDAY.

SATURDAY THROUGH TUESDAY...
THE COMBINATION OF A DRIER WESTERLY FLOW ALONG WITH RIDGING ALOFT
WILL LIKELY KEEP CHANCES FOR THUNDERSTORM ACTIVITY AT CLIMO...OR
BELOW LEVELS DURING THIS PERIOD. HOWEVER...IT STILL APPEARS THAT
THERE WILL BE ENOUGH RESIDUAL MOISTURE AROUND TO KEEP US FROM
ELIMINATING CHANCES FOR POPS ENTIRELY AT THIS POINT...WITH
TEMPERATURES RETURNING TO NEAR...OR SLIGHTLY ABOVE NORMAL VALUES.

&&

.AVIATION...
SOUTH-CENTRAL ARIZONA INCLUDING KPHX...KIWA...KSDL...
AS UPPER TROF APPROACHES FROM THE WEST AND MONSOON MOISTURE
INCREASES...STILL EXPECT SHOWERS AND THUNDERSTORMS TO INCREASE THIS
MORNING...BECOMING NUMEROUS BY 14-15Z. WILL KEEP MENTION OF
THUNDER...AS VCTS...IN TAFS THRU ABOUT 16Z...THEN FIGURE RAIN WILL
HAVE COOLED AND STABILIZED BOUNDARY LAYER ENOUGH THAT WE SHOULD BE
IN A MORE SHOWERY REGIME THAT WILL CONTINUE INTO THE AFTERNOON.
DEPENDING UPON HOW MUCH SUNSHINE IS SEEN THIS AFTERNOON THERE MAY BE
ANOTHER ROUND OF THUNDERSTORMS TO DEAL WITH AT THE TERMINALS. WILL
WAIT FOR LATER TO SEE HOW THAT PLAYS OUT. OTHERWISE WINDS SHOULD
FAVOR THE SOUTH TO SOUTHEAST THIS MORNING...TRANSITIONING MORE
TOWARDS SOUTHWEST IN THE AFTERNOON WITH SPEEDS MOSTLY AOB 12KT.

NOTE...IF SHOWERS/STORMS CONTINUE TO TAKE THEIR TIME
DEVELOPING...THE TAFS WILL BE OVERPLAYING THE WEATHER AND WILL NEED
TO BE UPDATED TO PUSH BACK THE PRECIP ONSET.

SOUTHWEST ARIZONA AND SOUTHEAST CALIFORNIA INCLUDING KIPL AND KBLH...
EXPECT SHOWERS/STORMS TO MOSTLY STAY EAST OF KIPL TODAY...WITH
COVERAGE AT KBLH TO BE MORE ON THE ISOLATED SIDE. WITH UPPER JET
APPROACHING...THERE WILL BE A THREAT FOR AFTN/EARLY EVE THUNDER AT
THE TERMINAL AND THUS WILL KEEP VCTS IN THE KBLH TAF. WINDS TO FAVOR
THE SOUTH AT KBLH...BECOMING GUSTY THIS AFTERNOON WITH SPEEDS AOB
20KT. AT KIPL...EXPECT MID/UPPER CLOUD DECKS TO SCATTER OUT BY 18Z
WITH WINDS TO SHIFT TOWARDS THE SOUTHWEST...BECOMING LOCALLY BREEZY
FROM THE WEST EARLY THIS EVENING.

AVIATION DISCUSSION NOT UPDATED FOR AMENDED TAFS.

&&

.FIRE WEATHER...
THURSDAY THROUGH MONDAY...
A SLIGHT CHANCE OF AFTERNOON AND EVENING THUNDERSTORMS WILL CONTINUE
MAINLY EAST OF THE LOWER COLORADO RIVER VALLEY ON THURSDAY WITH A
CHANCE ACROSS THE HIGHER TERRAIN EAST OF PHOENIX. LITTLE CHANGE IS
EXPECTED FRIDAY. HIGH TEMPERATURES BOTH DAYS WILL STAY BELOW
SEASONAL NORMALS...WITH COOLER DESERTS FALLING INTO THE 90S.
HUMIDITY LEVELS WILL STAY QUITE ELEVATED WITH MOST OF THE DESERTS
RECORDING MINIMUM RH VALUES BETWEEN 20 AND 30 PERCENT. A STEADY
SOUTHWEST FLOW ALOFT WILL LEAD TO GRADUAL DRYING AND WARMING
CONDITIONS OVER THE WEEKEND AND INTO EARLY NEXT WEEK. BY SUNDAY
THERE WILL BE JUST A SLIGHT CHANCE OF AFTERNOON AND EVENING
THUNDERSTORMS ACROSS THE HIGHER TERRAIN EAST OF PHOENIX WITH PARTLY
TO MOSTLY SUNNY SKIES EXPECTED ELSEWHERE. DESPITE THE DRYING
TREND...MINIMUM RH VALUES WILL STAY ON THE ELEVATED SIDE AND SHOULD
MOSTLY RANGE FROM 15 TO 25 PERCENT. NO STRONG WINDS ARE EXPECTED
THROUGH THE PERIOD...MAINLY NORMAL DIURNAL WINDS FAVORING THE SOUTH
TO SOUTHWEST LESS THAN 15 MPH.

&&

.PSR WATCHES/WARNINGS/ADVISORIES...

AZ...NONE.

CA...NONE.

&&

$$

VISIT US ON FACEBOOK...TWITTER...AND AT WEATHER.GOV/PHOENIX

DISCUSSION...PERCHA
AVIATION....CB
FIRE WEATHER...CB










000
FXUS65 KPSR 190844
AFDPSR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PHOENIX AZ
145 AM MST TUE AUG 19 2014

.SYNOPSIS...
AN EARLY SEASON PACIFIC LOW PRESSURE SYSTEM APPROACHING THE AREA
FROM THE WEST IS EXPECTED TO PRODUCE WIDESPREAD SHOWER AND
THUNDERSTORM ACTIVITY THROUGH THE DAY TODAY...WITH LESSER CHANCES
FOR CONVECTIVE ACTIVITY THROUGH FRIDAY AS THE LOW CENTER MOVES
SLOWLY EASTWARD ACROSS THE REGION. DRIER AIR SPREADING IN FROM THE
WEST WILL REDUCE THUNDERSTORM ACTIVITY FROM THIS WEEKEND INTO EARLY
NEXT WEEK. BELOW NORMAL TEMPERATURES ARE FORECAST FROM TODAY THROUGH
FRIDAY...WARMING THIS WEEKEND.

&&

.DISCUSSION...
TODAY...
STORM COVERAGE SO FAR THIS EARLY MORNING CONTINUES TO BE BEEN VERY
LIMITED...WITH A FEW SHOWERS NOW BEGINNING TO DEVELOP ACROSS LA
PAZ...MARICOPA...AND SOUTHERN GILA COUNTY AT THIS HOUR. WE ARE STILL
EXPECTING WIDESPREAD SHOWER AND THUNDERSTORM ACTIVITY TO DEVELOP
THROUGH THE REST OF THIS MORNING AS THE UPPER LOW THAT IS NOW
LOCATED JUST OFF THE CENTRAL CA COAST CONTINUES TO APPROACH THE
REGION. THE LATEST NAM/GFS/EURO MODEL SUITES CONTINUE TO SHOW THAT
SHOWERS/THUNDERSTORMS WILL DEVELOP ACROSS SW AND SOUTH-CENTRAL AZ
THIS MORNING...MAINLY ACROSS LA PAZ AND MARICOPA/PINAL/GILA
COUNTIES. HOWEVER RAINFALL AMOUNTS SEEM TO BE A BIT LESS THAN WHAT
WAS DEPICTED ON EARLIER RUNS...LIKELY DUE TO PWATS PEAKING IN THE
1.80-1.90 INCH RANGE...DOWN A BIT FROM THE 2.00-2.10 INCH THAT WAS
BEING FORECASTED YESTERDAY...BUT MOISTURE/DYNAMICS STILL APPEAR TO
BE GOOD ENOUGH TO JUSTIFY TO CONTINUE THE FORECAST FOR LOCALLY HEAVY
RAINFALL AMOUNTS...WITH THE BEST CHANCE FOR HEAVY RAINS TO BE BEFORE
NOON ACROSS SOUTH-CENTRAL AZ...AS A WEAK SHORTWAVE MOVES
NORTHEASTWARD ACROSS THE REGION. RAINFALL CHANCES WILL LIKELY DROP
NOTICEABLY THIS AFTERNOON/EVENING AS DRIER AIR BEGINS TO FILTER IN
FROM THE WEST BEHIND THIS SHORTWAVE AND THE ATMOSPHERE
STABILIZES...BUT HEAVY RAINFALL WILL STILL BE A POSSIBILITY OVER THE
FAVORED UPSLOPE AREAS OF SOUTHERN GILA COUNTY INTO TONIGHT. ALL THIS
RAINFALL/CLOUDS IS EXPECTED TO KEEP OUR HIGHS TODAY WELL BELOW
NORMAL...WITH MOST SOUTH-CENTRAL AZ LOWER DESERT LOCATIONS REMAINING
IN THE 90S.

WEDNESDAY AND WEDNESDAY NIGHT...
A SIGNIFICANT REDUCTION IN SHOWER/THUNDERSTORM ACTIVITY IS EXPECTED
ON WEDNESDAY AND WEDNESDAY NIGHT AS PWATS FALL INTO THE 1.25-150
INCH RANGE AS SOUTHWESTERLY FLOW ALOFT STRENGTHENS OVER THE REGION
AHEAD OF THE MAIN UPPER LOW CENTER. STILL...ISOLATED TO SCATTERED
STORMS CAN BE EXPECTED...WITH THE BEST CHANCES FOR STORMS BEING OVER
THE HIGHER TERRAIN NORTH AND EAST OF PHOENIX AS STRONGER WINDS ALOFT
INCREASES BULK SHEAR VALUES OVER THE REGION.

THURSDAY AND FRIDAY...
THE LIKELIHOOD OF A SECOND HEAVY RAIN EVENT ON THURSDAY/FRIDAY NOW
LOOKS TO BE SIGNIFICANTLY LESS...SINCE LATEST MODELS RUNS ARE NOW
SHOWING MUCH LESS TROPICAL MOISTURE...FROM TROPICAL STORM
LOWELL...BEING PULLED NORTHEASTWARD INTO THE REGION. THUS...HAVE
REDUCED POPS SOMEWHAT ON THU/FRI...BUT STILL KEEPING THINGS
BROADBRUSHED A BIT...SINCE THE EURO CONTINUES TO BE SLOWER WITH THE
MOVEMENT OF THE UPPER LOW CENTER...TAKING IT ACROSS AZ ON
FRIDAY...WHILE THE FASTER GFS CONTINUES TO MOVE IT THROUGH ON
THURSDAY.

SATURDAY THROUGH TUESDAY...
THE COMBINATION OF A DRIER WESTERLY FLOW ALONG WITH RIDGING ALOFT
WILL LIKELY KEEP CHANCES FOR THUNDERSTORM ACTIVITY AT CLIMO...OR
BELOW LEVELS DURING THIS PERIOD. HOWEVER...IT STILL APPEARS THAT
THERE WILL BE ENOUGH RESIDUAL MOISTURE AROUND TO KEEP US FROM
ELIMINATING CHANCES FOR POPS ENTIRELY AT THIS POINT...WITH
TEMPERATURES RETURNING TO NEAR...OR SLIGHTLY ABOVE NORMAL VALUES.

&&

.AVIATION...
SOUTH-CENTRAL ARIZONA INCLUDING KPHX...KIWA...KSDL...
UPPER TROUGH SWEEPING ONSHORE OVER THE CA COAST WILL BE THE TRIGGER
FOR SHOWER AND THUNDERSTORM ACTIVITY OVERNIGHT BUT NOT UNTIL LATER
OVERNIGHT. COVERAGE INITIALLY WILL BE ISOLATED IN NATURE BEFORE
BECOMING MORE WIDESPREAD TOWARDS 19/12Z. AS SUCH...HAVE MARCHED BACK
VCTS OR -SHRA MENTIONING IN THE TAFS TO AFTER 19/05Z. MOSTLY WEST
EVENING WINDS WITH SPEEDS GNLY 12 KTS OR LESS WILL CONTINUE.
FORECAST TAF GUIDANCE SUGGESTS SOUTHERLY TO SOUTHEASTERLY WINDS WILL
BACK OVER THE TERMINALS AFTER MIDNIGHT LOCAL AND LAST THROUGH THE
AM. EXPECT WIDESPREAD SHOWER AND EMBEDDED THUNDER BY EARLY TUE
AM...WITH -SHRA MENTIONING HOLDING IN THE TAFS BEGINNING AT OR
AROUND 19/10-11Z. BKN TO OVC CIGS LIKELY WITH THE OVERNIGHT/EARLY AM
PRECIP ACTIVITY AROUND 6-8KFT. COULD SEE LOCALLY LOWER CIGS UNDER
THE HEAVIEST SHOWER CORES...BUT UNTIL THOSE DEVELOP WILL HOLD OFF
INTRODUCING LOW END VFR CIGS FOR THE TERMINALS.

SOUTHWEST ARIZONA AND SOUTHEAST CALIFORNIA INCLUDING KIPL AND KBLH...
VERY ISOLATED SHOWER AND THUNDERSTORM ACTIVITY WILL PULSE OVER THE
DESERT AREA WITH VERY SUBTLE STORM MOTION TO THE NORTH. THINK
COVERAGE TONIGHT WILL BE MORE VICINITY...ESPECIALLY NEAR KBLH. WILL
TO CONTINUE FAVORING SOUTH TO SOUTHEAST HEADINGS 10-15KTS. SCT TO
BKN MID LEVEL CLOUDS WITH BASES AOA 10KFT LIKELY TO CONTINUE
OVERNIGHT AS WELL.

AVIATION DISCUSSION NOT UPDATED FOR AMENDED TAFS.

&&

.FIRE WEATHER...
THURSDAY THROUGH MONDAY...
WARMER AFTERNOON TEMPERATURES COMBINED WITH HIGHER THAN NORMAL
HUMIDITY WILL LEAD TO A CHANCE OF AFTERNOON AND EVENING SHOWERS AND
THUNDERSTORMS MAINLY ACROSS SOUTHWEST AND SOUTH CENTRAL ARIZONA...
WITH HIGHEST PRECIP PROBABILITIES IN THE MOUNTAINS OF SOUTHERN GILA
COUNTY. MINIMUM RELATIVE HUMIDITIES WILL RANGE FROM 25 TO 30
PERCENT. OVERNIGHT RECOVERY WILL BE GOOD.

&&

.PSR WATCHES/WARNINGS/ADVISORIES...

AZ...NONE.

CA...NONE.

&&

$$

VISIT US ON FACEBOOK...TWITTER...AND AT WEATHER.GOV/PHOENIX

DISCUSSION...PERCHA
AVIATION....NOLTE
FIRE WEATHER...VASQUEZ







000
FXUS65 KPSR 190844
AFDPSR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PHOENIX AZ
145 AM MST TUE AUG 19 2014

.SYNOPSIS...
AN EARLY SEASON PACIFIC LOW PRESSURE SYSTEM APPROACHING THE AREA
FROM THE WEST IS EXPECTED TO PRODUCE WIDESPREAD SHOWER AND
THUNDERSTORM ACTIVITY THROUGH THE DAY TODAY...WITH LESSER CHANCES
FOR CONVECTIVE ACTIVITY THROUGH FRIDAY AS THE LOW CENTER MOVES
SLOWLY EASTWARD ACROSS THE REGION. DRIER AIR SPREADING IN FROM THE
WEST WILL REDUCE THUNDERSTORM ACTIVITY FROM THIS WEEKEND INTO EARLY
NEXT WEEK. BELOW NORMAL TEMPERATURES ARE FORECAST FROM TODAY THROUGH
FRIDAY...WARMING THIS WEEKEND.

&&

.DISCUSSION...
TODAY...
STORM COVERAGE SO FAR THIS EARLY MORNING CONTINUES TO BE BEEN VERY
LIMITED...WITH A FEW SHOWERS NOW BEGINNING TO DEVELOP ACROSS LA
PAZ...MARICOPA...AND SOUTHERN GILA COUNTY AT THIS HOUR. WE ARE STILL
EXPECTING WIDESPREAD SHOWER AND THUNDERSTORM ACTIVITY TO DEVELOP
THROUGH THE REST OF THIS MORNING AS THE UPPER LOW THAT IS NOW
LOCATED JUST OFF THE CENTRAL CA COAST CONTINUES TO APPROACH THE
REGION. THE LATEST NAM/GFS/EURO MODEL SUITES CONTINUE TO SHOW THAT
SHOWERS/THUNDERSTORMS WILL DEVELOP ACROSS SW AND SOUTH-CENTRAL AZ
THIS MORNING...MAINLY ACROSS LA PAZ AND MARICOPA/PINAL/GILA
COUNTIES. HOWEVER RAINFALL AMOUNTS SEEM TO BE A BIT LESS THAN WHAT
WAS DEPICTED ON EARLIER RUNS...LIKELY DUE TO PWATS PEAKING IN THE
1.80-1.90 INCH RANGE...DOWN A BIT FROM THE 2.00-2.10 INCH THAT WAS
BEING FORECASTED YESTERDAY...BUT MOISTURE/DYNAMICS STILL APPEAR TO
BE GOOD ENOUGH TO JUSTIFY TO CONTINUE THE FORECAST FOR LOCALLY HEAVY
RAINFALL AMOUNTS...WITH THE BEST CHANCE FOR HEAVY RAINS TO BE BEFORE
NOON ACROSS SOUTH-CENTRAL AZ...AS A WEAK SHORTWAVE MOVES
NORTHEASTWARD ACROSS THE REGION. RAINFALL CHANCES WILL LIKELY DROP
NOTICEABLY THIS AFTERNOON/EVENING AS DRIER AIR BEGINS TO FILTER IN
FROM THE WEST BEHIND THIS SHORTWAVE AND THE ATMOSPHERE
STABILIZES...BUT HEAVY RAINFALL WILL STILL BE A POSSIBILITY OVER THE
FAVORED UPSLOPE AREAS OF SOUTHERN GILA COUNTY INTO TONIGHT. ALL THIS
RAINFALL/CLOUDS IS EXPECTED TO KEEP OUR HIGHS TODAY WELL BELOW
NORMAL...WITH MOST SOUTH-CENTRAL AZ LOWER DESERT LOCATIONS REMAINING
IN THE 90S.

WEDNESDAY AND WEDNESDAY NIGHT...
A SIGNIFICANT REDUCTION IN SHOWER/THUNDERSTORM ACTIVITY IS EXPECTED
ON WEDNESDAY AND WEDNESDAY NIGHT AS PWATS FALL INTO THE 1.25-150
INCH RANGE AS SOUTHWESTERLY FLOW ALOFT STRENGTHENS OVER THE REGION
AHEAD OF THE MAIN UPPER LOW CENTER. STILL...ISOLATED TO SCATTERED
STORMS CAN BE EXPECTED...WITH THE BEST CHANCES FOR STORMS BEING OVER
THE HIGHER TERRAIN NORTH AND EAST OF PHOENIX AS STRONGER WINDS ALOFT
INCREASES BULK SHEAR VALUES OVER THE REGION.

THURSDAY AND FRIDAY...
THE LIKELIHOOD OF A SECOND HEAVY RAIN EVENT ON THURSDAY/FRIDAY NOW
LOOKS TO BE SIGNIFICANTLY LESS...SINCE LATEST MODELS RUNS ARE NOW
SHOWING MUCH LESS TROPICAL MOISTURE...FROM TROPICAL STORM
LOWELL...BEING PULLED NORTHEASTWARD INTO THE REGION. THUS...HAVE
REDUCED POPS SOMEWHAT ON THU/FRI...BUT STILL KEEPING THINGS
BROADBRUSHED A BIT...SINCE THE EURO CONTINUES TO BE SLOWER WITH THE
MOVEMENT OF THE UPPER LOW CENTER...TAKING IT ACROSS AZ ON
FRIDAY...WHILE THE FASTER GFS CONTINUES TO MOVE IT THROUGH ON
THURSDAY.

SATURDAY THROUGH TUESDAY...
THE COMBINATION OF A DRIER WESTERLY FLOW ALONG WITH RIDGING ALOFT
WILL LIKELY KEEP CHANCES FOR THUNDERSTORM ACTIVITY AT CLIMO...OR
BELOW LEVELS DURING THIS PERIOD. HOWEVER...IT STILL APPEARS THAT
THERE WILL BE ENOUGH RESIDUAL MOISTURE AROUND TO KEEP US FROM
ELIMINATING CHANCES FOR POPS ENTIRELY AT THIS POINT...WITH
TEMPERATURES RETURNING TO NEAR...OR SLIGHTLY ABOVE NORMAL VALUES.

&&

.AVIATION...
SOUTH-CENTRAL ARIZONA INCLUDING KPHX...KIWA...KSDL...
UPPER TROUGH SWEEPING ONSHORE OVER THE CA COAST WILL BE THE TRIGGER
FOR SHOWER AND THUNDERSTORM ACTIVITY OVERNIGHT BUT NOT UNTIL LATER
OVERNIGHT. COVERAGE INITIALLY WILL BE ISOLATED IN NATURE BEFORE
BECOMING MORE WIDESPREAD TOWARDS 19/12Z. AS SUCH...HAVE MARCHED BACK
VCTS OR -SHRA MENTIONING IN THE TAFS TO AFTER 19/05Z. MOSTLY WEST
EVENING WINDS WITH SPEEDS GNLY 12 KTS OR LESS WILL CONTINUE.
FORECAST TAF GUIDANCE SUGGESTS SOUTHERLY TO SOUTHEASTERLY WINDS WILL
BACK OVER THE TERMINALS AFTER MIDNIGHT LOCAL AND LAST THROUGH THE
AM. EXPECT WIDESPREAD SHOWER AND EMBEDDED THUNDER BY EARLY TUE
AM...WITH -SHRA MENTIONING HOLDING IN THE TAFS BEGINNING AT OR
AROUND 19/10-11Z. BKN TO OVC CIGS LIKELY WITH THE OVERNIGHT/EARLY AM
PRECIP ACTIVITY AROUND 6-8KFT. COULD SEE LOCALLY LOWER CIGS UNDER
THE HEAVIEST SHOWER CORES...BUT UNTIL THOSE DEVELOP WILL HOLD OFF
INTRODUCING LOW END VFR CIGS FOR THE TERMINALS.

SOUTHWEST ARIZONA AND SOUTHEAST CALIFORNIA INCLUDING KIPL AND KBLH...
VERY ISOLATED SHOWER AND THUNDERSTORM ACTIVITY WILL PULSE OVER THE
DESERT AREA WITH VERY SUBTLE STORM MOTION TO THE NORTH. THINK
COVERAGE TONIGHT WILL BE MORE VICINITY...ESPECIALLY NEAR KBLH. WILL
TO CONTINUE FAVORING SOUTH TO SOUTHEAST HEADINGS 10-15KTS. SCT TO
BKN MID LEVEL CLOUDS WITH BASES AOA 10KFT LIKELY TO CONTINUE
OVERNIGHT AS WELL.

AVIATION DISCUSSION NOT UPDATED FOR AMENDED TAFS.

&&

.FIRE WEATHER...
THURSDAY THROUGH MONDAY...
WARMER AFTERNOON TEMPERATURES COMBINED WITH HIGHER THAN NORMAL
HUMIDITY WILL LEAD TO A CHANCE OF AFTERNOON AND EVENING SHOWERS AND
THUNDERSTORMS MAINLY ACROSS SOUTHWEST AND SOUTH CENTRAL ARIZONA...
WITH HIGHEST PRECIP PROBABILITIES IN THE MOUNTAINS OF SOUTHERN GILA
COUNTY. MINIMUM RELATIVE HUMIDITIES WILL RANGE FROM 25 TO 30
PERCENT. OVERNIGHT RECOVERY WILL BE GOOD.

&&

.PSR WATCHES/WARNINGS/ADVISORIES...

AZ...NONE.

CA...NONE.

&&

$$

VISIT US ON FACEBOOK...TWITTER...AND AT WEATHER.GOV/PHOENIX

DISCUSSION...PERCHA
AVIATION....NOLTE
FIRE WEATHER...VASQUEZ






000
FXUS65 KPSR 190317
AFDPSR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PHOENIX AZ
817 PM MST MON AUG 18 2014

.SYNOPSIS...
AN EARLY SEASON PACIFIC LOW PRESSURE SYSTEM WILL APPROACH THE AREA
TONIGHT...AND WILL DRAW MORE MONSOON MOISTURE NORTH INTO ARIZONA. A
CHANCE OF WIDESPREAD SHOWER AND THUNDERSTORM ACTIVITY IS EXPECTED
ACROSS ARIZONA FROM LATE TONIGHT THROUGH MUCH OF THIS WEEK. WITH THE
INCREASED HUMIDITY AND VARIABLE CLOUDINESS...BELOW NORMAL
TEMPERATURES ARE FORECAST TUESDAY THROUGH FRIDAY...WARMING THIS
WEEKEND.

&&

.DISCUSSION...
STORM COVERAGE SO FAR THIS EVENING HAS BEEN VERY LIMITED...WITH THE
ONLY PERSISTENT ACTIVITY PULSING OVER NORTHERN LA PAZ COUNTY NEAR
ALAMO LAKE...WARRANTING AN SMALL STREAM FLOOD ADVISORY. CLOUD COVER
WAS SLOW TO DISSIPATE EARLIER IN THE DAY AND ALONG WITH WITH COOLER
DAYTIME TEMPERATURES...BOTH PHOENIX AND YUMA TOPPED OUT AT
98F...ATMOSPHERIC CONDITIONS WERE MOSTLY STABLE THROUGH THE EARLY
AFTERNOON AND EVENING. FOCUS OF STORM ACTIVITY LATE TODAY HAS BEEN TO
OUR NORTHWEST THROUGH NORTHEAST...WITH ACTIVITY NORTH OF I-40 FROM CA
INTO NV AND ACROSS NORTHERN AZ. THUNDERSTORM COVERAGE ACROSS
SOUTHEAST AZ HAS BEEN SLOW SO FAR THIS EVENING...WITH THE BEST STORMS
NOW FIRING TO THE NORTHEAST OF TUCSON AND BY ORO VALLEY.

FOR THE REST OF THIS EARLY EVENING...DREW BACK OUR POP FORECAST TO
HIGHLIGHT ISOLATED THUNDER MENTION FOR LOCATIONS EAST OF THE COLORADO
RIVER VALLEY...AND DROPPING MENTION FOR THE NEXT FEW HOURS ACROSS
THE PHOENIX METRO /AZZ023/. THE EARLY SEASON PACIFIC LOW WAS PLOTTED
NEAR THE BAY AREA THIS EVENING WITH SHORTWAVE HEIGHTS STRETCHING AS
FAR SOUTH AS BAJA. GFS/NAM 500MB STREAMLINE FORECASTS THIS EVENING
SHOW TWO DISTINCT WAVE FEATURES TO OUR WEST/SOUTHWEST WITH THE FIRST
ALREADY DRAPED OVER SOUTHEAST CA. OUTSIDE OF THE LONG-LIVED STORM
COVERAGE OVER NORTHERN LA PAZ WHICH HAVE SLOWLY BEEN BUILDING TO THE
SOUTH...BEGINNING TO SEE VERY ISOLATED PULSE STORMS NOW OVER WESTERN
PIMA COUNTY ALONG THE SHORTWAVE LOBE. COUPLE THAT WITH A UNSEASONABLY
STRONG UPPER JET...AT LEAST 2 STANDARD DEVIATIONS ABOVE NORMAL AT
200MB AND 60-70KT 300-250MB CORE...WILL LOOK FOR SHOWER ACTIVITY TO
QUICKLY EXPAND IN COVERAGE THROUGH THE EARLY MORNING HOURS WITH THAT
UPPER LEVEL LIFT SUPPORT. POP FORECAST REMAINS MUCH THE SAME FOR
19/06-12Z TIMEFRAME WITH WIDESPREAD...AND POTENTIALLY HEAVY AT
TIMES...SHOWER ACTIVITY POSSIBLE FOR THE TUESDAY AM COMMUTE ACROSS
THE SOUTH-CENTRAL AZ DESERTS AND POINTS EAST.

&&

.PREVIOUS DISCUSSION /ISSUED AT 255 PM MST/PDT...
TONIGHT THROUGH TUESDAY...
CONCERN FOR THIS EVENING THROUGH THE FIRST HALF OF TUESDAY IS AN
EVEN STRONGER DIFLUENT/DYNAMICAL PATTERN ALOFT DEVELOPING OVER OUR
FORECAST AREA...ASSOCIATED WITH A SOUTHWARD MOVING EARLY SEASON COOL
TROF ALONG THE WEST COAST. AS A RESULT...ADDITIONAL MONSOON MOISTURE
WILL FLOW NORTH FROM MEXICO INTO SOUTHWEST AZ THIS EVENING...AND
INTO SOUTH CENTRAL AZ LATE TONIGHT. AS A RESULT...A GOOD CHANCE OF
WIDESPREAD SHOWER AND THUNDERSTORM ACTIVITY IS FORECAST ACROSS THE
CWA. THE BEST TIMING FOR POTENTIAL RAIN IN SOUTH CENTRAL AZ...
INCLUDING PHOENIX...WILL BE FROM MIDNIGHT THROUGH 9 AM TUESDAY.

THE HEAVY PRECIPITATION BRANCH IS CONSISTENT WITH THEIR HEAVY RAIN
FORECASTS ACROSS MOST OF AZ FROM TONIGHT THROUGH TUESDAY NIGHT.

FOR LATER TUESDAY AND TUESDAY NIGHT...A MORE STABLE BUT VERY HUMID
ATMOSPHERE WILL DEVELOP. SHOWER POTENTIAL SHOULD BE REDUCED
CONSIDERABLY.

WEDNESDAY THROUGH THURSDAY...
THERE ARE MODEL DISCREPANCIES REGARDING THE FUTURE MOVEMENT OF THE
SOUTHERN CA TROF THAT STALLS TONIGHT AND TUESDAY. THE GFS HAS BEEN
VERY CONSISTENT WITH MOVING IT INLAND WEDNESDAY NIGHT AND ACCEPTED.
THIS TROF HAS THE POTENTIAL TO PRODUCING ANOTHER WIDESPREAD AND
HEAVY RAIN EVENT IN SOUTH CENTRAL AZ...INCLUDING PHOENIX
WEDNESDAY NIGHT. PRECIP PROBABILITIES FOR WEDNESDAY NIGHT ARE
ELEVATED AGAIN IN SOUTH CENTRAL AZ.

FRIDAY THROUGH SUNDAY...
LESS CONFIDENCE IS EXPECTED THIS PERIOD. WARMER AFTERNOONS COMBINED
WITH CONTINUED HIGH HUMIDITY...AND UNKNOWN WEAK PERTURBATIONS...
WARRANT THE FORECAST OF A LOW GRADE MONSOON SO TO SPEAK...MEANING A
BROAD BRUSH SLIGHT CHANCE OF AFTERNOON/EARLY EVENING SHOWERS AND
THUNDERSTORMS APPROACH.

&&

.AVIATION...
SOUTH-CENTRAL ARIZONA INCLUDING KPHX...KIWA...KSDL...
UPPER TROUGH SWEEPING ONSHORE OVER THE CA COAST WILL BE THE TRIGGER
FOR SHOWER AND THUNDERSTORM ACTIVITY OVERNIGHT BUT NOT UNTIL LATER
OVERNIGHT. COVERAGE INITIALLY WILL BE ISOLATED IN NATURE BEFORE
BECOMING MORE WIDESPREAD TOWARDS 19/12Z. AS SUCH...HAVE MARCHED BACK VCTS
OR -SHRA MENTIONING IN THE TAFS TO AFTER 19/05Z. MOSTLY WEST EVENING
WINDS WITH SPEEDS GNLY 12 KTS OR LESS WILL CONTINUE. FORECAST TAF
GUIDANCE SUGGESTS SOUTHERLY TO SOUTHEASTERLY WINDS WILL BACK OVER THE
TERMINALS AFTER MIDNIGHT LOCAL AND LAST THROUGH THE AM. EXPECT
WIDESPREAD SHOWER AND EMBEDDED THUNDER BY EARLY TUE AM...WITH -SHRA
MENTIONING HOLDING IN THE TAFS BEGINNING AT OR AROUND 19/10-11Z. BKN
TO OVC CIGS LIKELY WITH THE OVERNIGHT/EARLY AM PRECIP ACTIVITY AROUND
6-8KFT. COULD SEE LOCALLY LOWER CIGS UNDER THE HEAVIEST SHOWER
CORES...BUT UNTIL THOSE DEVELOP WILL HOLD OFF INTRODUCING LOW END VFR
CIGS FOR THE TERMINALS.

SOUTHWEST ARIZONA AND SOUTHEAST CALIFORNIA INCLUDING KIPL AND KBLH...
VERY ISOLATED SHOWER AND THUNDERSTORM ACTIVITY WILL PULSE OVER THE
DESERT AREA WITH VERY SUBTLE STORM MOTION TO THE NORTH. THINK
COVERAGE TONIGHT WILL BE MORE VICINITY...ESPECIALLY NEAR KBLH. WILL
TO CONTINUE FAVORING SOUTH TO SOUTHEAST HEADINGS 10-15KTS. SCT TO
BKN MID LEVEL CLOUDS WITH BASES AOA 10KFT LIKELY TO CONTINUE
OVERNIGHT AS WELL.

AVIATION DISCUSSION NOT UPDATED FOR AMENDED TAFS.

&&

.FIRE WEATHER...
THURSDAY THROUGH MONDAY...
WARMER AFTERNOON TEMPERATURES COMBINED WITH HIGHER THAN NORMAL
HUMIDITY WILL LEAD TO A CHANCE OF AFTERNOON AND EVENING SHOWERS AND
THUNDERSTORMS MAINLY ACROSS SOUTHWEST AND SOUTH CENTRAL ARIZONA...
WITH HIGHEST PRECIP PROBABILITIES IN THE MOUNTAINS OF SOUTHERN GILA
COUNTY. MINIMUM RELATIVE HUMIDITIES WILL RANGE FROM 25 TO 30
PERCENT. OVERNIGHT RECOVERY WILL BE GOOD.

&&

.PSR WATCHES/WARNINGS/ADVISORIES...

AZ...NONE.

CA...NONE.

&&

$$

VISIT US ON FACEBOOK...TWITTER...AND AT WEATHER.GOV/PHOENIX

DISCUSSION...NOLTE
PREVIOUS DISCUSSION...VASQUEZ/PERCHA
AVIATION....NOLTE
FIRE WEATHER...VASQUEZ







000
FXUS65 KPSR 190317
AFDPSR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PHOENIX AZ
817 PM MST MON AUG 18 2014

.SYNOPSIS...
AN EARLY SEASON PACIFIC LOW PRESSURE SYSTEM WILL APPROACH THE AREA
TONIGHT...AND WILL DRAW MORE MONSOON MOISTURE NORTH INTO ARIZONA. A
CHANCE OF WIDESPREAD SHOWER AND THUNDERSTORM ACTIVITY IS EXPECTED
ACROSS ARIZONA FROM LATE TONIGHT THROUGH MUCH OF THIS WEEK. WITH THE
INCREASED HUMIDITY AND VARIABLE CLOUDINESS...BELOW NORMAL
TEMPERATURES ARE FORECAST TUESDAY THROUGH FRIDAY...WARMING THIS
WEEKEND.

&&

.DISCUSSION...
STORM COVERAGE SO FAR THIS EVENING HAS BEEN VERY LIMITED...WITH THE
ONLY PERSISTENT ACTIVITY PULSING OVER NORTHERN LA PAZ COUNTY NEAR
ALAMO LAKE...WARRANTING AN SMALL STREAM FLOOD ADVISORY. CLOUD COVER
WAS SLOW TO DISSIPATE EARLIER IN THE DAY AND ALONG WITH WITH COOLER
DAYTIME TEMPERATURES...BOTH PHOENIX AND YUMA TOPPED OUT AT
98F...ATMOSPHERIC CONDITIONS WERE MOSTLY STABLE THROUGH THE EARLY
AFTERNOON AND EVENING. FOCUS OF STORM ACTIVITY LATE TODAY HAS BEEN TO
OUR NORTHWEST THROUGH NORTHEAST...WITH ACTIVITY NORTH OF I-40 FROM CA
INTO NV AND ACROSS NORTHERN AZ. THUNDERSTORM COVERAGE ACROSS
SOUTHEAST AZ HAS BEEN SLOW SO FAR THIS EVENING...WITH THE BEST STORMS
NOW FIRING TO THE NORTHEAST OF TUCSON AND BY ORO VALLEY.

FOR THE REST OF THIS EARLY EVENING...DREW BACK OUR POP FORECAST TO
HIGHLIGHT ISOLATED THUNDER MENTION FOR LOCATIONS EAST OF THE COLORADO
RIVER VALLEY...AND DROPPING MENTION FOR THE NEXT FEW HOURS ACROSS
THE PHOENIX METRO /AZZ023/. THE EARLY SEASON PACIFIC LOW WAS PLOTTED
NEAR THE BAY AREA THIS EVENING WITH SHORTWAVE HEIGHTS STRETCHING AS
FAR SOUTH AS BAJA. GFS/NAM 500MB STREAMLINE FORECASTS THIS EVENING
SHOW TWO DISTINCT WAVE FEATURES TO OUR WEST/SOUTHWEST WITH THE FIRST
ALREADY DRAPED OVER SOUTHEAST CA. OUTSIDE OF THE LONG-LIVED STORM
COVERAGE OVER NORTHERN LA PAZ WHICH HAVE SLOWLY BEEN BUILDING TO THE
SOUTH...BEGINNING TO SEE VERY ISOLATED PULSE STORMS NOW OVER WESTERN
PIMA COUNTY ALONG THE SHORTWAVE LOBE. COUPLE THAT WITH A UNSEASONABLY
STRONG UPPER JET...AT LEAST 2 STANDARD DEVIATIONS ABOVE NORMAL AT
200MB AND 60-70KT 300-250MB CORE...WILL LOOK FOR SHOWER ACTIVITY TO
QUICKLY EXPAND IN COVERAGE THROUGH THE EARLY MORNING HOURS WITH THAT
UPPER LEVEL LIFT SUPPORT. POP FORECAST REMAINS MUCH THE SAME FOR
19/06-12Z TIMEFRAME WITH WIDESPREAD...AND POTENTIALLY HEAVY AT
TIMES...SHOWER ACTIVITY POSSIBLE FOR THE TUESDAY AM COMMUTE ACROSS
THE SOUTH-CENTRAL AZ DESERTS AND POINTS EAST.

&&

.PREVIOUS DISCUSSION /ISSUED AT 255 PM MST/PDT...
TONIGHT THROUGH TUESDAY...
CONCERN FOR THIS EVENING THROUGH THE FIRST HALF OF TUESDAY IS AN
EVEN STRONGER DIFLUENT/DYNAMICAL PATTERN ALOFT DEVELOPING OVER OUR
FORECAST AREA...ASSOCIATED WITH A SOUTHWARD MOVING EARLY SEASON COOL
TROF ALONG THE WEST COAST. AS A RESULT...ADDITIONAL MONSOON MOISTURE
WILL FLOW NORTH FROM MEXICO INTO SOUTHWEST AZ THIS EVENING...AND
INTO SOUTH CENTRAL AZ LATE TONIGHT. AS A RESULT...A GOOD CHANCE OF
WIDESPREAD SHOWER AND THUNDERSTORM ACTIVITY IS FORECAST ACROSS THE
CWA. THE BEST TIMING FOR POTENTIAL RAIN IN SOUTH CENTRAL AZ...
INCLUDING PHOENIX...WILL BE FROM MIDNIGHT THROUGH 9 AM TUESDAY.

THE HEAVY PRECIPITATION BRANCH IS CONSISTENT WITH THEIR HEAVY RAIN
FORECASTS ACROSS MOST OF AZ FROM TONIGHT THROUGH TUESDAY NIGHT.

FOR LATER TUESDAY AND TUESDAY NIGHT...A MORE STABLE BUT VERY HUMID
ATMOSPHERE WILL DEVELOP. SHOWER POTENTIAL SHOULD BE REDUCED
CONSIDERABLY.

WEDNESDAY THROUGH THURSDAY...
THERE ARE MODEL DISCREPANCIES REGARDING THE FUTURE MOVEMENT OF THE
SOUTHERN CA TROF THAT STALLS TONIGHT AND TUESDAY. THE GFS HAS BEEN
VERY CONSISTENT WITH MOVING IT INLAND WEDNESDAY NIGHT AND ACCEPTED.
THIS TROF HAS THE POTENTIAL TO PRODUCING ANOTHER WIDESPREAD AND
HEAVY RAIN EVENT IN SOUTH CENTRAL AZ...INCLUDING PHOENIX
WEDNESDAY NIGHT. PRECIP PROBABILITIES FOR WEDNESDAY NIGHT ARE
ELEVATED AGAIN IN SOUTH CENTRAL AZ.

FRIDAY THROUGH SUNDAY...
LESS CONFIDENCE IS EXPECTED THIS PERIOD. WARMER AFTERNOONS COMBINED
WITH CONTINUED HIGH HUMIDITY...AND UNKNOWN WEAK PERTURBATIONS...
WARRANT THE FORECAST OF A LOW GRADE MONSOON SO TO SPEAK...MEANING A
BROAD BRUSH SLIGHT CHANCE OF AFTERNOON/EARLY EVENING SHOWERS AND
THUNDERSTORMS APPROACH.

&&

.AVIATION...
SOUTH-CENTRAL ARIZONA INCLUDING KPHX...KIWA...KSDL...
UPPER TROUGH SWEEPING ONSHORE OVER THE CA COAST WILL BE THE TRIGGER
FOR SHOWER AND THUNDERSTORM ACTIVITY OVERNIGHT BUT NOT UNTIL LATER
OVERNIGHT. COVERAGE INITIALLY WILL BE ISOLATED IN NATURE BEFORE
BECOMING MORE WIDESPREAD TOWARDS 19/12Z. AS SUCH...HAVE MARCHED BACK VCTS
OR -SHRA MENTIONING IN THE TAFS TO AFTER 19/05Z. MOSTLY WEST EVENING
WINDS WITH SPEEDS GNLY 12 KTS OR LESS WILL CONTINUE. FORECAST TAF
GUIDANCE SUGGESTS SOUTHERLY TO SOUTHEASTERLY WINDS WILL BACK OVER THE
TERMINALS AFTER MIDNIGHT LOCAL AND LAST THROUGH THE AM. EXPECT
WIDESPREAD SHOWER AND EMBEDDED THUNDER BY EARLY TUE AM...WITH -SHRA
MENTIONING HOLDING IN THE TAFS BEGINNING AT OR AROUND 19/10-11Z. BKN
TO OVC CIGS LIKELY WITH THE OVERNIGHT/EARLY AM PRECIP ACTIVITY AROUND
6-8KFT. COULD SEE LOCALLY LOWER CIGS UNDER THE HEAVIEST SHOWER
CORES...BUT UNTIL THOSE DEVELOP WILL HOLD OFF INTRODUCING LOW END VFR
CIGS FOR THE TERMINALS.

SOUTHWEST ARIZONA AND SOUTHEAST CALIFORNIA INCLUDING KIPL AND KBLH...
VERY ISOLATED SHOWER AND THUNDERSTORM ACTIVITY WILL PULSE OVER THE
DESERT AREA WITH VERY SUBTLE STORM MOTION TO THE NORTH. THINK
COVERAGE TONIGHT WILL BE MORE VICINITY...ESPECIALLY NEAR KBLH. WILL
TO CONTINUE FAVORING SOUTH TO SOUTHEAST HEADINGS 10-15KTS. SCT TO
BKN MID LEVEL CLOUDS WITH BASES AOA 10KFT LIKELY TO CONTINUE
OVERNIGHT AS WELL.

AVIATION DISCUSSION NOT UPDATED FOR AMENDED TAFS.

&&

.FIRE WEATHER...
THURSDAY THROUGH MONDAY...
WARMER AFTERNOON TEMPERATURES COMBINED WITH HIGHER THAN NORMAL
HUMIDITY WILL LEAD TO A CHANCE OF AFTERNOON AND EVENING SHOWERS AND
THUNDERSTORMS MAINLY ACROSS SOUTHWEST AND SOUTH CENTRAL ARIZONA...
WITH HIGHEST PRECIP PROBABILITIES IN THE MOUNTAINS OF SOUTHERN GILA
COUNTY. MINIMUM RELATIVE HUMIDITIES WILL RANGE FROM 25 TO 30
PERCENT. OVERNIGHT RECOVERY WILL BE GOOD.

&&

.PSR WATCHES/WARNINGS/ADVISORIES...

AZ...NONE.

CA...NONE.

&&

$$

VISIT US ON FACEBOOK...TWITTER...AND AT WEATHER.GOV/PHOENIX

DISCUSSION...NOLTE
PREVIOUS DISCUSSION...VASQUEZ/PERCHA
AVIATION....NOLTE
FIRE WEATHER...VASQUEZ








    US Dept of Commerce
    National Oceanic and Atmospheric Administration
    National Weather Service
    1325 East West Highway
    Silver Spring, MD 20910
    Page Author: NWS Internet Services Team
Disclaimer
Information Quality
Credits
Glossary
Privacy Policy
Freedom of Information Act (FOIA)
About Us
Career Opportunities