[top]
000
FXUS65 KTFX 210457
AFDTFX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
1100 PM MDT SUN MAY 20 2012
.DISCUSSION...
TONIGHT THROUGH TUESDAY...AN UPPER LEVEL RIDGE OF HIGH PRESSURE
WILL REMAIN OVER THE TFX CWA TONIGHT...KEEPING OVERNIGHT LOWS
ABOUT 5 TO 10 DEGREES WARMER THAN NORMAL. HOWEVER...A WEAK
DISTURBANCE WILL MOVE OVER THE TOP OF THE RIDGE...POSSIBLY
BRINGING ISOLATED SHOWERS TO THE AREA...ESPECIALLY OVER THE
MOUNTAINS AND ALONG THE HI-LINE. AN UPPER LEVEL TROUGH OF LOW
PRESSURE WILL THEN MOVE INTO THE PACIFIC NORTHWEST MONDAY INTO
MONDAY NIGHT...BRINGING AN INCREASINGLY MOIST AND UNSTABLE
SOUTHWESTERLY FLOW ALOFT TO THE AREA. AS A RESULT THE CHANCE FOR
SHOWERS WILL INCREASE AS WELL ACROSS THE AREA. A COLD FRONT WILL
ALSO MOVE INTO THE AREA DURING THE DAY ON MONDAY TO COMBINE WITH
WEAK TO MODERATE INSTABILITY FOR A CHANCE OF THUNDERSTORMS.
TEMPERATURES AHEAD OF THIS COLD FRONT WILL REMAIN AROUND 10
DEGREES ABOVE NORMAL MONDAY THROUGH MONDAY NIGHT. THE COLD FRONT
WILL GRADUALLY MOVE ACROSS THE AREA MONDAY NIGHT THROUGH TUESDAY
AS A SHORTWAVE TROUGH EJECTS FROM THE MAIN UPPER LEVEL TROUGH.
HOWEVER...THE CHANCE FOR SHOWERS AND THUNDERSTORMS WILL DECREASE
DURING THE DAY ON TUESDAY AS BREEZY WESTERLY DOWNSLOPE WINDS
DEVELOP IN THE WAKE OF THE COLD FRONT...AS TEMPERATURES FALL BACK
CLOSER TO NORMAL. COULSTON
TUESDAY NIGHT THROUGH SUNDAY...AS HAS BEEN ADVERTISED IT STILL
LOOKS LIKE A COOL AND UNSETTLED PERIOD. THE FIRST PROBLEM TO DEAL
WITH IS WHERE AN UPPER LOW WILL BE ON WEDNESDAY. AS HAS BEEN THE
CASE AT LEAST SINCE YESTERDAY THE GFS MODEL HAS THE UPPER LOW
OVER NORTHEAST MONTANA WITH PRECIPITATION SPREADING SOUTH OVER
MUCH OF THE FORECAST AREA IN THE NORTHERLY FLOW ALOFT ON THE
BACKSIDE OF THE UPPER LOW. OTHER MODELS KEEP THE UPPER LOW IN
CANADA ALONG WITH MOST OF THE ASSOCIATED PRECIPITATION. OTHER
MODEL RUNS OF THE GFS SUGGEST THE LATEST GFS IS OFF THE MARK SO
WILL GO WITH A DRIER FORECAST. MEANWHILE A STRONG UPPER LOW OFF
THE B.C. COAST ON WEDNESDAY IS FORECAST TO DRIVE SOUTHEAST TO
NEAR THE NORTHERN CALIFORNIA COAST BY LATE THURSDAY NIGHT. IN
RESPONSE SOUTHERLY FLOW ALOFT AND MOISTURE INCREASE OVER THE
FORECAST AREA. THIS MOISTURE WILL INTERACT WITH A A COOLER
CANADIAN AIRMASS WHICH WILL SPREAD SOUTH THURSDAY. THIS WILL
RESULT IN AT LEAST AREAS OF RAIN IF NOT WIDESPREAD RAIN THURSDAY
NIGHT WHICH COULD LAST AT LEAST INTO THE EARLY PART OF THE
HOLIDAY WEEKEND. THE GFS IS SLOWER THAN THE GEM AND ECMWF MODELS
WITH TRENDS MENTIONED ABOVE..HOLDING OFF ON THE MORE WIDESPREAD
PRECIPITATION UNTIL FRIDAY. SINCE THE GEM AND ECMWF ARE MORE LIKE
ONE ANOTHER THAN EITHER IS WITH THE GFS WILL GO WITH A FASTER
DEVELOPMENT OF PRECIPITATION. THERE IS UNCERTAINTY WITH HOW LOW
SNOW LEVELS WILL GO BUT THINK THERE WILL BE SNOW IN THE
MOUNTAINS. IN FACT THE NORTHERN PLAINS COULD EVEN SEE A MIX OF
SNOW AND RAIN IF NOT ALL SNOW BY EARLY FRIDAY. BLANK
&&
.AVIATION...
UPDATED 0500Z.
VFR CONDITIONS EXPECTED TONIGHT. MOISTURE WILL INCREASE FROM THE
WEST TOMORROW AS A LOW PRESSURE SYSTEM BEGINS TO MOVE INTO
THE REGION. SOME CONVECTIVE ACTIVITY AHEAD OF THIS SYSTEM MAY ALLOW
FOR SOME THUNDERSTORMS TO DEVELOP ACROSS CENTRAL MONTANA MONDAY
AFTERNOON AND EVENING. GENERALLY WESTERLY WINDS WILL REMAIN LIGHT
OVERALL THROUGH THE PERIOD. IFR CONDITIONS ARE TO BE EXPECTED NEAR
ANY STORM CELLS THAT MAY DEVELOP. ERRATIC AND GUSTY WINDS MAY ALSO
BE SEEN NEAR COLLAPSING STORMS.
&&
.PRELIMINARY POINT TEMPS/POPS...
GTF 49 79 54 64 / 10 30 60 60
CTB 44 72 50 61 / 20 30 50 40
HLN 46 82 52 63 / 10 30 50 60
BZN 40 82 49 63 / 10 30 40 60
WEY 31 73 36 53 / 10 20 30 70
DLN 43 80 49 61 / 10 30 40 60
HVR 46 79 56 67 / 20 10 50 60
LWT 44 78 52 62 / 10 30 40 60
&&
.TFX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
WEATHER.GOV/GREATFALLS
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000
FXUS65 KBYZ 210318
AFDBYZ
AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE BILLINGS MT
918 PM MDT SUN MAY 20 2012
.SHORT TERM...VALID FOR MON AND TUE...
VERY WEAK SHOWERS OVER WESTERN AND CENTRAL ZONES HAVE DISSIPATED.
SPRINKLES WERE MENTIONED IN THE ZONES AND REMOVED THEM FOR THIS
UPDATE. BUILDING RIDGE FOR THE REST OF THE NIGHT SHOULD DEFLECT
FORCING NORTH OF THE AREA. ENOUGH CLOUDS SHOULD BE AROUND TO KEEP
TEMPERATURES UP AND KEPT LOWS CLOSE TO GUIDANCE AS HOURLIES IN
LINE. REST OF FORECAST PACKAGE LOOKS IN GOOD SHAPE. TWH
.LONG TERM...VALID FOR WED...THU...FRI...SAT...SUN...
THE THEME FOR THE EXTENDED FORECAST REMAINS COOLER AND UNSETTLED
WEATHER. OPERATIONAL COMPUTER MODELS AGREE ON THE OVERALL
EVOLUTION OF THE PATTERN BUT DISAGREE ON MANY OF THE IMPORTANT
DETAILS.
THE EXTENDED FORECAST BEGINS ON WEDNESDAY WITH A PACIFIC TROUGH
INFLUENCING THE SENSIBLE WEATHER ACROSS THE REGION. THE TROUGH
WILL HAVE ALREADY PUSHED A COLD FRONT ACROSS THE AREA ON TUESDAY
AND THE ASSOCIATED SHOWER AND THUNDERSTORM ACTIVITY WILL BE
DIMINISHING BY WEDNESDAY MORNING. BY WEDNESDAY THE BULK OF THE QG
FORCING WITH THE WAVE WILL HAVE SHIFTED NORTHWARD INTO CANADA.
THE GFS...CANADIAN GEM...AND SREF ARE IN THE BEST CONSENSUS AS TO
THE LOCATION OF THE 500 MB LOW ON WEDNESDAY. THESE MODELS POSITION
THE LOW OVER NORTHERN MONTANA AND SOUTHERN CANADA...WHILE THE
ECMWF IS FURTHER NORTH AND WEAKER WITH THE LOW. THUS HAVE DECIDED
TO TAKE MY LEAD FROM THE 12Z GFS AND CANADIAN MODELS. THIS PATTERN
ALSO SETS UP FAVORABLE CONDITIONS FOR A WINDY DAY ACROSS THE AREA
ON WEDNESDAY. THE NEARLY STACKED 500/700/850 MB LOW CENTERS JUST
TO OUR NORTH SET UP A DEEP LAYER OF WESTERLY WINDS IN THE 30 TO 45
KNOT RANGE. THIS ALONG WITH STRONG MIXING BEHIND THE COLD FRONT
WILL LEAD STRONG AND GUSTY WESTERLY WINDS ON WEDNESDAY. THESE
DOWNSLOPE WINDS ACROSS THE PLAINS SHOULD FURTHER HELP TO INHIBIT
WIDESPREAD SHOWERS ON WEDNESDAY. HOWEVER... DUE TO THE MOIST FLOW
IT IS HARDER TO RULE OUT SHOWERS IN THE MOUNTAINS.
MODEL CONSENSUS IS FOR THE UPPER LEVEL LOW TO SLIDE TOWARD THE EAST
ON THURSDAY BEFORE BECOMING PICKED UP BY THE NORTHERN STREAM OF
THE JET LATE ON THURSDAY. THIS WILL ALLOW FOR THE FLOW ACROSS THE
REGION TO TURN NORTHERLY DURING THE DAY ON THURSDAY. THIS APPEARS
TO HELP GENERATE SOME FRONTOGENSIS ACROSS THE AREA ALONG WITH
UPSLOPE FLOW ALONG NORTH FACING FOOTHILLS. THUS HAVE DECIDED TO
CONTINUE TO RAISE POPS ON THURSDAY. HAVE ALSO DECIDED TO LOWER THE
TEMPERATURES A BIT MORE FOR THURSDAY DUE TO COOL 850 MB
TEMPERATURES AND POTENTIAL FOR RAIN SHOWERS KEEPING US EVEN
COOLER.
BY FRIDAY AND INTO SATURDAY MODEL CONSENSUS HAS BEEN GOOD IN
AMPLIFYING THE PATTERN. THE MODELS ARE ALL PRETTY AGGRESSIVE IN
AMPLIFYING A RIDGE OVER THE PACIFIC OCEAN THAT LEADS TO THE
DOWNSTREAM DEVELOPMENT OF A TROUGH OVER CALIFORNIA AND A BUILDING
RIDGE OVER THE SOUTHEAST CONUS. THE ECMWF CANADIAN GEM AND EARLIER
RUNS OF THE GFS ARE IN GOOD AGREEMENT TO SHIFT THE JET STREAM
NORTH OF OUR AREA IN SOUTHWESTERLY FLOW. THIS SENDS A WARM FRONT
NORTH ACROSS OUR AREA ON SATURDAY AND GETS US INTO A POTENTIAL
THUNDERSTORM OR HEAVY RAIN SCENARIO DEPENDING ON THE TRACK OF THE
LOW. THE 12Z RUN OF THE GFS THROWS A WRENCH INTO THIS THINKING AS IT
DEVELOPS A WEAKER LOW AND KEEPS US ON THE COOL SIDE OF THE
JET STREAM. REGARDLESS...THE POTENTIAL EXISTS FOR A WET MEMORIAL
DAY WEEKEND AND MODEL TRENDS WILL NEED TO BE WATCHED TO PIN DOWN
THE DETAILS ON HOW THIS PACIFIC TROUGH WILL EVOLVE. CHURCH
&&
.AVIATION...
VFR CONDITIONS WILL PREVAIL THROUGHOUT THE TAF PERIOD. ISOLATED
THUNDERSTORMS WILL DEVELOP WEST OF KBIL BY LATE MONDAY AFTERNOON.
STRONG WIND GUSTS WILL BE THE PRIMARY THREAT FROM THESE STORMS.
BRS
&&
.PRELIMINARY POINT TEMP/POPS...
MON TUE WED THU FRI SAT SUN
-----------------------------------------------------------
BIL 052/088 058/073 044/061 040/057 042/062 045/069 048/070
00/B 16/T 43/T 24/W 33/W 43/T 43/T
LVM 045/085 050/063 036/055 035/055 034/058 039/067 039/068
12/T 26/T 43/T 35/W 44/W 44/T 43/T
HDN 048/090 056/076 044/063 040/059 042/066 045/073 048/073
00/U 16/T 43/T 24/W 33/W 43/T 33/T
MLS 053/089 060/079 047/065 044/060 043/065 048/071 050/074
00/B 15/T 32/T 24/W 33/W 43/T 33/T
4BQ 050/087 057/081 046/063 043/060 042/065 047/074 052/077
00/U 04/T 43/T 24/W 33/W 42/T 33/T
BHK 046/085 054/080 045/062 042/059 042/062 045/068 053/074
00/B 03/T 42/T 24/W 33/W 43/T 33/T
SHR 045/085 054/076 041/059 039/058 040/065 042/074 044/074
00/U 05/T 53/T 34/W 33/W 42/T 33/T
&&
.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...NONE.
WY...NONE.
&&
$$
WEATHER.GOV/BILLINGS
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000
FXUS65 KGGW 210308 AAA
AFDGGW
AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE GLASGOW MT
908 PM MDT SUN MAY 20 2012
.SHORT TERM...FOR NORTHEAST MONTANA...TONIGHT THROUGH TUESDAY...
A QUIET EVENING WILL PRECLUDE MUCH IN THE WAY OF AN UPDATE. THE
GREAT FALLS RADAR IS SHOWING AN AREA OF WEAK ECHOES MOVING INTO
HILL COUNTY. THESE SHOWERS SHOW UP ON THE GFS FOR 00Z-06Z THIS
EVENING. THE GFS AFTER MIDNIGHT MOVES THESE SHOWERS INTO SOUTHERN
SASKATCHEWAN JUST TO OUR NORTH. THE INHERITED POP AND WX GRIDS
ALREADY HANDLE THIS WELL. SO CHANGES TONIGHT WILL BE IN THE AREA
OF SMALL TWEAKS BASED ON CURRENT OBSERVATIONS. NO SIGNIFICANT
CHANGES ARE NEEDED. SCT
PREVIOUS DISCUSSION...
WATER VAPOR IMAGERY AND 500 MB HEIGHT FIELD SHOWS THE SLOW-MOVING
WEATHER PATTERN ACROSS THE CONUS. TROPICAL STORM ALBERTO HAS
WEAKENED SOMEWHAT OFF THE SOUTH CAROLINA COASTLINE...BUT HAS ALSO
SPUN OFF ANOTHER PIECE OF ENERGY AND CIRCULATION WHICH MAY FORM
INTO ANOTHER SEPARATE TROPICAL STORM. A FAIRLY STRONG UPPER LEVEL
RIDGE IS IN PLACE OVER THE REMAINDER OF THE EAST COAST AND NEW
ENGLAND STATES WHILE A MORE SUBTLE AND GENERAL WEAK RIDGE SLOWLY
SLIDES OVER THE SOUTHWEST...INTER-MOUNTAIN WEST...AND NORTHERN
HIGH PLAINS. THE UPPER LEVEL TROUGH PUSHING THROUGH THE MIDDLE
PORTION OF THE COUNTRY CONTINUES TO SPAWN THUNDERSTORMS FROM THE
NORTHERN GREAT LAKES THROUGH THE MID-MISSISSIPPI RIVER VALLEY.
CLOUDINESS AND SOUTHWEST FLOW ALOFT IS BEGINNING TO INCREASE OVER
THE PACIFIC NORTHWEST...PREVIEWING THE NEXT LARGE STORM SYSTEM.
A RELATIVELY QUIET HIGH PRESSURE AT THE SURFACE HAS ALLOWED QUITE
A BIT OF SUNSHINE TO REACH THE SURFACE WITH SOME PARTLY CLOUDY
SKIES OVER SOME OF OUR EASTERN ZONES. TEMPERATURES HAVE REACHED
INTO THE LOWER 70S FOR LOCATIONS NOT NEAR THE INTERNATIONAL BORDER.
ONE MORE DAY OF WARMER TEMPERATURES...CALMER WINDS...AND PARTLY
CLOUDY SKIES WITH A FEW SCATTERED PERIMETER SPRINKLES CAN BE
EXPECTED ON MONDAY. TEMPERATURES WILL CLIMB TO NEAR 10 DEGREES
WARMER THAN TODAY WAS.
MONDAY NIGHT...THE MAIN DYNAMICS BEGIN TO SPIN UP AND DRAMATICALLY
INCREASE CHANCES FOR ACCUMULATING PRECIPITATION AS THE NEXT STORM
SYSTEM TAKES AIM FOR THE NORTHERN ROCKIES AND THE NORTHERN HIGH
PLAINS.
TUESDAY WILL BE THE MAIN CHALLENGE IN THE THE FORECAST. SHORT
TERM MODELS ARE BEGINNING TO COALESCE AROUND A COMMON SOLUTION
SHOWING QUITE A BIT OF MEASURABLE PRECIPITATION MOVING THROUGH OUR
CWA EARLY TUESDAY MORNING THROUGH LATE TUESDAY NIGHT. ALTHOUGH
CONDITIONS WILL BE MUCH MORE FAVORABLE FOR SEVERE WEATHER FURTHER
TO OUR EAST...OVER THE DAKOTAS...SOME SEVERE WEATHER PARAMETERS ARE
SHOWING INDICATIONS OF INCREASED RISK FOR AT LEAST SOME LOW-END
SEVERE WEATHER CONNECTED TO THE MAIN COLD FRONT WHICH IS EXPECTED
TO PASS THROUGH SOMETIME TUESDAY AFTERNOON. CAPE VALUES WILL BE
BETWEEN 200 AND 500 J/KG. LCL AS LOW AS 1700 FT...LIFTED INDEX
VALUES BETWEEN -2 AND -4 WILL ACCOMPANY THE COLD FRONT AND MAY
PROVIDE ENOUGH INSTABILITY TO SET OFF SOME MARGINALLY SEVERE
THUNDERSTORMS. FOR NOW...DECIDED TO INCREASE POPS...QPF...AND
DAMAGING WIND WORDING IN THE GRIDS. ALSO INCREASED SURFACE WIND
SPEEDS AND GUSTS GENERALLY ACROSS THE CWA...AND MORE SPECIFICALLY
NEAR THE LITTLE ROCKIES WHERE STRONGER WINDS ALWAYS SEEM TO FUNNEL
DOWN THROUGH THE MALTA SOUTH US-HWY 191 DOT SITE. BMICKELSON
.LONG TERM...TUESDAY NIGHT THROUGH SUNDAY...
ONLY MINOR CHANGES TO ONGOING FORECAST. MODELS CONTINUE WITH
FAIRLY POOR CONSENSUS REGARDING UPPER LOW DIGGING INTO THE GREAT
BASIN THEN LIFTING TOWARD THE NORTHERN PLAINS SOMETIME OVER THE
WEEKEND. INDICATIONS ARE A REASONABLY GOOD CHANCE FOR RAIN
SOMETIME DURING THE PERIOD BUT NO CLEAR INDICATION OF WHEN EXACTLY
THAT WILL OCCUR. CONTINUED WITH THE LOWER CHANCE POPS THROUGH MOST
OF THE EXTENDED PERIOD WITH TEMPERATURES GENERALLY BELOW CLIMO.
EBERT
PREVIOUS LONG TERM DISCUSSION...MODELS CONTINUE TO PLACE THE
UPPER LOW DIFFERENTLY ON WEDNESDAY AND WEDNESDAY NIGHT WITH GFS
FAVORING MONTANA AND ECMWF AND ECMWF PUTTING THE LOW IN
SASKATCHEWAN. BOTH MODELS HAVE EASTERN MONTANA IN A DRY SLOT FOR
AT LEAST PART OF THE DAY WHICH WILL ALLOW FOR DAYTIME HEATING TO
DESTABILIZE THE ATMOSPHERE. MAY SEE SOME SHOWERS AND THUNDERSTORMS
DEVELOP AS A RESULT. WILL MENTION A SLIGHT CHANCE FOR NOW.
THE MODEL DIFFERENCES CONTINUE WEDNESDAY NIGHT AND THURSDAY WITH
THE ECMWF AND GEM KEEPING THE UPPER LOW IN SASKATCHEWAN AND DRY
SLOT OVER EASTERN MONTANA WHILE THE GFS TRACKS ITS UPPER LOW INTO
NORTH DAKOTA AND MANITOBA AND BRINGS WRAP AROUND PRECIP THROUGH
EASTERN MONTANA. WILL MAINTAIN A CHANCE OF SHOWERS GIVEN THE UNCERTAINTY.
FRIDAY AND SATURDAY...THE NEXT UPPER LOW DIGS SOUTH INTO NORTHERN
CALIFORNIA WITH RIDGE TO THE EAST. MONTANA WILL BE IN A SOUTHWEST
FLOW ALOFT. ALL THE MODELS DEPICT A PERIOD OF OVERRUNNING MOISTURE
AHEAD OF A WARM OR OCCLUDED FRONT AT SOME POINT FRIDAY AND
SATURDAY. WILL MAINTAIN A CHANCE OF SHOWERS FOR NOW.
THE ECMWF AND GEM WANT TO LIFT THIS LOW NORTH ACROSS WESTERN
MONTANA NEXT SUNDAY WHILE THE GFS KEEPS THE LOW IN CALIFORNIA.
WILL MAINTAIN A CHANCE OF SHOWERS FOR NOW GIVEN THE MODEL
DIFFERENCES. FORRESTER
&&
.AVIATION...
VFR. WILL SEE MID LEVEL CLOUDS AT TIMES OVERNIGHT. SOUTHEAST WINDS
WILL TURN NORTHWEST MONDAY MORNING FOLLOWING A WEAK FRONTAL
PASSAGE.
&&
.GLASGOW WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
WEATHER.GOV/GLASGOW
000
FXUS65 KTFX 210304
AFDTFX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
904 PM MDT SUN MAY 20 2012
.UPDATE...PACIFIC MOISTURE MOVING OVER THE TOP OF THE WEAK RIDGE
ALOFT HAS COMBINED WITH A WEAK DISTURBANCE TO TRIGGER AREAS OF
SPRINKLES AND A FEW LIGHT SHOWERS THIS EVENING. HAVE UPDATED TO
INCREASE POPS AND COVERAGE OF SPRINKLES IN THE FORECAST GRIDS AND
TEXT PRODUCTS. HAVE ALSO MADE TWEAKS TO INCREASE CLOUD COVER FOR
THIS EVENING. MODELS STILL SHOW THIS MOISTURE MOVING OUT OF THE
REGION OVERNIGHT WITH NOT MUCH IN THE WAY OF QPF ANTICIPATED.
MONDAY IS EXPECTED TO BE WARM WITH AN INCREASING CHANCE OF SHOWERS
AND THUNDERSTORMS DURING THE AFTERNOON AND EVENING AS ANOTHER
SYSTEM MOVES INTO THE REGION. MPJ
&&
.AVIATION...
UPDATED 0000Z.
VFR CONDITIONS EXPECTED OVER MOST OF MONTANA TONIGHT. MOISTURE
EMBEDDED IN WESTERLY FLOW ALOFT WILL BRING ISOLATED SHOWERS AND A
THUNDERSTORM OR TWO MAINLY TO SOUTHWEST MT INTO THE EVENING HOURS.
CONVECTIVE ACTIVITY WILL TAPER OFF AFTER SUNSET. GENERALLY WESTERLY
WINDS WILL REMAIN LIGHT THROUGH THE NIGHT.
&&
.PREV DISCUSSION...
/ISSUED 600 PM MDT SUN MAY 20 2012/
TONIGHT THROUGH TUESDAY...AN UPPER LEVEL RIDGE OF HIGH PRESSURE
WILL REMAIN OVER THE TFX CWA TONIGHT...KEEPING OVERNIGHT LOWS
ABOUT 5 TO 10 DEGREES WARMER THAN NORMAL. HOWEVER...A WEAK
DISTURBANCE WILL MOVE OVER THE TOP OF THE RIDGE...POSSIBLY
BRINGING ISOLATED SHOWERS TO THE AREA...ESPECIALLY OVER THE
MOUNTAINS AND ALONG THE HI-LINE. AN UPPER LEVEL TROUGH OF LOW
PRESSURE WILL THEN MOVE INTO THE PACIFIC NORTHWEST MONDAY INTO
MONDAY NIGHT...BRINGING AN INCREASINGLY MOIST AND UNSTABLE
SOUTHWESTERLY FLOW ALOFT TO THE AREA. AS A RESULT THE CHANCE FOR
SHOWERS WILL INCREASE AS WELL ACROSS THE AREA. A COLD FRONT WILL
ALSO MOVE INTO THE AREA DURING THE DAY ON MONDAY TO COMBINE WITH
WEAK TO MODERATE INSTABILITY FOR A CHANCE OF THUNDERSTORMS.
TEMPERATURES AHEAD OF THIS COLD FRONT WILL REMAIN AROUND 10
DEGREES ABOVE NORMAL MONDAY THROUGH MONDAY NIGHT. THE COLD FRONT
WILL GRADUALLY MOVE ACROSS THE AREA MONDAY NIGHT THROUGH TUESDAY
AS A SHORTWAVE TROUGH EJECTS FROM THE MAIN UPPER LEVEL TROUGH.
HOWEVER...THE CHANCE FOR SHOWERS AND THUNDERSTORMS WILL DECREASE
DURING THE DAY ON TUESDAY AS BREEZY WESTERLY DOWNSLOPE WINDS
DEVELOP IN THE WAKE OF THE COLD FRONT...AS TEMPERATURES FALL BACK
CLOSER TO NORMAL. COULSTON
TUESDAY NIGHT THROUGH SUNDAY...AS HAS BEEN ADVERTISED IT STILL
LOOKS LIKE A COOL AND UNSETTLED PERIOD. THE FIRST PROBLEM TO DEAL
WITH IS WHERE AN UPPER LOW WILL BE ON WEDNESDAY. AS HAS BEEN THE
CASE AT LEAST SINCE YESTERDAY THE GFS MODEL HAS THE UPPER LOW
OVER NORTHEAST MONTANA WITH PRECIPITATION SPREADING SOUTH OVER
MUCH OF THE FORECAST AREA IN THE NORTHERLY FLOW ALOFT ON THE
BACKSIDE OF THE UPPER LOW. OTHER MODELS KEEP THE UPPER LOW IN
CANADA ALONG WITH MOST OF THE ASSOCIATED PRECIPITATION. OTHER
MODEL RUNS OF THE GFS SUGGEST THE LATEST GFS IS OFF THE MARK SO
WILL GO WITH A DRIER FORECAST. MEANWHILE A STRONG UPPER LOW OFF
THE B.C. COAST ON WEDNESDAY IS FORECAST TO DRIVE SOUTHEAST TO
NEAR THE NORTHERN CALIFORNIA COAST BY LATE THURSDAY NIGHT. IN
RESPONSE SOUTHERLY FLOW ALOFT AND MOISTURE INCREASE OVER THE
FORECAST AREA. THIS MOISTURE WILL INTERACT WITH A A COOLER
CANADIAN AIRMASS WHICH WILL SPREAD SOUTH THURSDAY. THIS WILL
RESULT IN AT LEAST AREAS OF RAIN IF NOT WIDESPREAD RAIN THURSDAY
NIGHT WHICH COULD LAST AT LEAST INTO THE EARLY PART OF THE
HOLIDAY WEEKEND. THE GFS IS SLOWER THAN THE GEM AND ECMWF MODELS
WITH TRENDS MENTIONED ABOVE..HOLDING OFF ON THE MORE WIDESPREAD
PRECIPITATION UNTIL FRIDAY. SINCE THE GEM AND ECMWF ARE MORE LIKE
ONE ANOTHER THAN EITHER IS WITH THE GFS WILL GO WITH A FASTER
DEVELOPMENT OF PRECIPITATION. THERE IS UNCERTAINTY WITH HOW LOW
SNOW LEVELS WILL GO BUT THINK THERE WILL BE SNOW IN THE
MOUNTAINS. IN FACT THE NORTHERN PLAINS COULD EVEN SEE A MIX OF
SNOW AND RAIN IF NOT ALL SNOW BY EARLY FRIDAY. BLANK
&&
.PRELIMINARY POINT TEMPS/POPS...
GTF 49 79 54 64 / 20 30 60 60
CTB 44 72 50 61 / 20 30 50 40
HLN 46 82 52 63 / 10 30 50 60
BZN 40 82 49 63 / 10 30 40 60
WEY 31 73 36 53 / 10 20 30 70
DLN 43 80 49 61 / 10 30 40 60
HVR 46 79 56 67 / 20 10 50 60
LWT 44 78 52 62 / 10 30 40 60
&&
.TFX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
WEATHER.GOV/GREATFALLS
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000
FXUS65 KMSO 210213
AFDMSO
Area Forecast Discussion
National Weather Service Missoula MT
813 PM MDT Sun May 20 2012
.UPDATE...Increased the chance of precipitation for the northern
Clearwater mountains and northwest Montana.
&&
.DISCUSSION...a plume of moisture is causing widespread light
showers across eastern Oregon and Washington as well as the
northern panhandle of Idaho. These showers will move into
northwest Montana this evening. The convection is anticipated to
decrease slightly with the main focus of showers being across the
northern Clearwater and Bitterroot mountains after midnight.
&&
.AVIATION...
Clouds will increase and lower across the northern Rockies during
the next 24 hours...as a storm system bears down on the region.
Terrain obscurations will become more numerous after 21/0600Z due
to increase in rain shower activity. Winds near the ground are
anticipated to remain fairly weak during this time.
&&
.PREV DISCUSSION... /ISSUED 235 PM MDT Sun May 20 2012/
DISCUSSION...
Temperatures will remain fairly mild tonight, as cloud cover
increases ahead of a storm system to arrive on Monday.
A big pattern change will occur at the beginning of the week with
a strong pacific low pressure system tracking across the
northwest. An associated cold front will begin to affect
northwestern Montana Monday morning/early afternoon with light
precipitation and thick clouds...which will keep high
temperatures a few degrees below normal. The cold front will
slowly move to the southeast allowing valley locations from Missoula
south and east to warm into the mid 70s. The atmosphere is
expected to be very unstable ahead of the front so brief heavy
rain and the possibility for thunderstorms will not be out of the
question. Once the front pushes through much cooler air will move
in overnight Monday and early Tuesday morning. Some of the highest mountain
locations could see some snow showers...but no heavy accumulations
are expected. Valley locations throughout western Montana and
central Idaho will still have some off and on light rain showers with
high temperatures only reaching the mid 50s.
Confidence is high that an active pattern with below average
temperatures will dominate the western US through this week. There
will also be high chances for showers this week, though the placement
and amounts are still uncertain. If your plans take you into the
high terrain this week, be prepared for high mountain snowfall and
cool temperatures. Current indications point to the potential for
the cool and wet pattern to continue through Memorial Day weekend.
AVIATION...
Clouds will increase and lower across the northern Rockies during
the next 24 hours...as a storm system bears down on the region.
Terrain obscurations will become more numerous after 21/0600Z due
to increase in rain shower activity. Winds near the ground are
anticipated to remain fairly weak during this time.
&&
.MSO WATCHES/WARNINGS/ADVISORIES...
MT...None.
ID...None.
&&
$$
Update...ts
Prev Discussion...dz/lr/jk
Aviation...dz
000
FXUS65 KTFX 210001
AFDTFX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
600 PM MDT SUN MAY 20 2012
.DISCUSSION...
TONIGHT THROUGH TUESDAY...AN UPPER LEVEL RIDGE OF HIGH PRESSURE
WILL REMAIN OVER THE TFX CWA TONIGHT...KEEPING OVERNIGHT LOWS
ABOUT 5 TO 10 DEGREES WARMER THAN NORMAL. HOWEVER...A WEAK
DISTURBANCE WILL MOVE OVER THE TOP OF THE RIDGE...POSSIBLY
BRINGING ISOLATED SHOWERS TO THE AREA...ESPECIALLY OVER THE
MOUNTAINS AND ALONG THE HI-LINE. AN UPPER LEVEL TROUGH OF LOW
PRESSURE WILL THEN MOVE INTO THE PACIFIC NORTHWEST MONDAY INTO
MONDAY NIGHT...BRINGING AN INCREASINGLY MOIST AND UNSTABLE
SOUTHWESTERLY FLOW ALOFT TO THE AREA. AS A RESULT THE CHANCE FOR
SHOWERS WILL INCREASE AS WELL ACROSS THE AREA. A COLD FRONT WILL
ALSO MOVE INTO THE AREA DURING THE DAY ON MONDAY TO COMBINE WITH
WEAK TO MODERATE INSTABILITY FOR A CHANCE OF THUNDERSTORMS.
TEMPERATURES AHEAD OF THIS COLD FRONT WILL REMAIN AROUND 10
DEGREES ABOVE NORMAL MONDAY THROUGH MONDAY NIGHT. THE COLD FRONT
WILL GRADUALLY MOVE ACROSS THE AREA MONDAY NIGHT THROUGH TUESDAY
AS A SHORTWAVE TROUGH EJECTS FROM THE MAIN UPPER LEVEL TROUGH.
HOWEVER...THE CHANCE FOR SHOWERS AND THUNDERSTORMS WILL DECREASE
DURING THE DAY ON TUESDAY AS BREEZY WESTERLY DOWNSLOPE WINDS
DEVELOP IN THE WAKE OF THE COLD FRONT...AS TEMPERATURES FALL BACK
CLOSER TO NORMAL. COULSTON
TUESDAY NIGHT THROUGH SUNDAY...AS HAS BEEN ADVERTISED IT STILL
LOOKS LIKE A COOL AND UNSETTLED PERIOD. THE FIRST PROBLEM TO DEAL
WITH IS WHERE AN UPPER LOW WILL BE ON WEDNESDAY. AS HAS BEEN THE
CASE AT LEAST SINCE YESTERDAY THE GFS MODEL HAS THE UPPER LOW
OVER NORTHEAST MONTANA WITH PRECIPITATION SPREADING SOUTH OVER
MUCH OF THE FORECAST AREA IN THE NORTHERLY FLOW ALOFT ON THE
BACKSIDE OF THE UPPER LOW. OTHER MODELS KEEP THE UPPER LOW IN
CANADA ALONG WITH MOST OF THE ASSOCIATED PRECIPITATION. OTHER
MODEL RUNS OF THE GFS SUGGEST THE LATEST GFS IS OFF THE MARK SO
WILL GO WITH A DRIER FORECAST. MEANWHILE A STRONG UPPER LOW OFF
THE B.C. COAST ON WEDNESDAY IS FORECAST TO DRIVE SOUTHEAST TO
NEAR THE NORTHERN CALIFORNIA COAST BY LATE THURSDAY NIGHT. IN
RESPONSE SOUTHERLY FLOW ALOFT AND MOISTURE INCREASE OVER THE
FORECAST AREA. THIS MOISTURE WILL INTERACT WITH A A COOLER
CANADIAN AIRMASS WHICH WILL SPREAD SOUTH THURSDAY. THIS WILL
RESULT IN AT LEAST AREAS OF RAIN IF NOT WIDESPREAD RAIN THURSDAY
NIGHT WHICH COULD LAST AT LEAST INTO THE EARLY PART OF THE
HOLIDAY WEEKEND. THE GFS IS SLOWER THAN THE GEM AND ECMWF MODELS
WITH TRENDS MENTIONED ABOVE..HOLDING OFF ON THE MORE WIDESPREAD
PRECIPITATION UNTIL FRIDAY. SINCE THE GEM AND ECMWF ARE MORE LIKE
ONE ANOTHER THAN EITHER IS WITH THE GFS WILL GO WITH A FASTER
DEVELOPMENT OF PRECIPITATION. THERE IS UNCERTAINTY WITH HOW LOW
SNOW LEVELS WILL GO BUT THINK THERE WILL BE SNOW IN THE
MOUNTAINS. IN FACT THE NORTHERN PLAINS COULD EVEN SEE A MIX OF
SNOW AND RAIN IF NOT ALL SNOW BY EARLY FRIDAY. BLANK
&&
.AVIATION...
UPDATED 0000Z.
VFR CONDITIONS EXPECTED OVER MOST OF MONTANA TONIGHT. MOISTURE
EMBEDDED IN WESTERLY FLOW ALOFT WILL BRING ISOLATED SHOWERS AND A
THUNDERSTORM OR TWO MAINLY TO SOUTHWEST MT INTO THE EVENING HOURS.
CONVECTIVE ACTIVITY WILL TAPER OFF AFTER SUNSET. GENERALLY WESTERLY
WINDS WILL REMAIN LIGHT THROUGH THE NIGHT.
&&
.PRELIMINARY POINT TEMPS/POPS...
GTF 49 79 54 64 / 10 30 60 60
CTB 44 72 50 61 / 20 30 50 40
HLN 46 82 52 63 / 10 30 50 60
BZN 40 82 49 63 / 10 30 40 60
WEY 31 73 36 53 / 10 20 30 70
DLN 43 80 49 61 / 10 30 40 60
HVR 46 79 56 67 / 20 10 50 60
LWT 44 78 52 62 / 10 30 40 60
&&
.TFX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
WEATHER.GOV/GREATFALLS
000
FXUS65 KBYZ 202133
AFDBYZ
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BILLINGS MT
333 PM MDT SUN MAY 20 2012
.SHORT TERM...VALID FOR MON AND TUE...
WEAK SHORTWAVE ACTIVITY MOVING THROUGH WESTERN AND CENTRAL MONTANA
WILL CONTINUE TO BRING A SLIGHT CHANCE OF SHOWERS TO WESTERN AND
CENTRAL ZONES THROUGH EARLY THIS EVENING. WITH CAPE VALUES OF A
FEW HUNDRED J/KG...WEAK SHEAR PROFILES...AND THE SHORTWAVE
ACTIVITY BEING COUNTERACTED BY RIDGING ALOFT...NOT EXPECTING ANY
THUNDERSTORMS. HIGH CLOUDS WILL KEEP TEMPS MILD TONIGHT.
MONDAY...WITH 700 MB TEMPS IN THE SINGLE DIGITS ABOVE ZERO AND A
GOOD DEAL OF FILTERED SUNSHINE...MIXING WILL ENABLE SURFACE TEMPS
TO REACH THE MID TO UPPER 80S. DURING THE LATE AFTERNOON/EVENING
HOURS...STRONGER SHORTWAVE ENERGY AHEAD OF AN APPROACHING UPPER
LEVEL TROUGH WILL MOVE ACROSS THE WESTERN HALF OF THE REGION.
CAPE AND SHEAR VALUES WILL STILL NOT BE VERY FAVORABLE FOR
THUNDERSTORMS...AND DEWPOINTS WILL REMAIN IN THE 30S AND 40S...SO
SHOWERS WILL BE CONFINED TO THE WESTERN MOUNTAINS AND FOOTHILLS.
AS THE UPPER LEVEL TROUGH...WHICH WILL BE SUPPORTING A STRONG
SURFACE COLD FRONT...MOVES TOWARDS THE REGION MONDAY NIGHT INTO
EARLY TUESDAY MORNING...SCATTERED SHOWERS AND ISOLATED
THUNDERSTORMS WILL INCREASE ACROSS THE WEST...AND BEGIN TO MOVE
INTO CENTRAL ZONES.
THE UPPER LEVEL TROUGH AND SURFACE COLD FRONT WILL CONTINUE TO
PUSH EASTWARD THROUGH THE DAY ON TUESDAY. STRONG UPPER LEVEL
DYNAMICS...AND STRONG LOW TO MID LEVEL FRONTOGENESIS ALONG WITH
DECENT OMEGA WILL COMBINE TO INCREASE THE POTENTIAL FOR SHOWERS
ACROSS MUCH OF THE REGION. THERE WILL LIKELY BE A FEW
THUNDERSTORMS AS A RESULT OF THE FORCING...BUT CAPE VALUES DO NOT
LOOK TO BE HIGH...SO NOT EXPECTING ANYTHING SEVERE. STRONG
PRESSURE RISES AND COLD AIR ADVECTION WILL ENABLE NW WINDS TO
BECOME VERY GUSTY BEHIND THE COLD FRONT. THE THREAT OF SHOWERS
WILL CONTINUE INTO TUESDAY NIGHT...ESPECIALLY ACROSS SOUTHEASTERN
MONTANA TUESDAY NIGHT DUE TO UPSLOPE NW WINDS. STC
.LONG TERM...VALID FOR WED...THU...FRI...SAT...SUN...
THE THEME FOR THE EXTENDED FORECAST REMAINS COOLER AND UNSETTLED
WEATHER. OPERATIONAL COMPUTER MODELS AGREE ON THE OVERALL
EVOLUTION OF THE PATTERN BUT DISAGREE ON MANY OF THE IMPORTANT
DETAILS.
THE EXTENDED FORECAST BEGINS ON WEDNESDAY WITH A PACIFIC TROUGH
INFLUENCING THE SENSIBLE WEATHER ACROSS THE REGION. THE TROUGH
WILL HAVE ALREADY PUSHED A COLD FRONT ACROSS THE AREA ON TUESDAY
AND THE ASSOCIATED SHOWER AND THUNDERSTORM ACTIVITY WILL BE
DIMINISHING BY WEDNESDAY MORNING. BY WEDNESDAY THE BULK OF THE QG
FORCING WITH THE WAVE WILL HAVE SHIFTED NORTHWARD INTO CANADA.
THE GFS...CANADIAN GEM...AND SREF ARE IN THE BEST CONSENSUS AS TO
THE LOCATION OF THE 500 MB LOW ON WEDNESDAY. THESE MODELS POSITION
THE LOW OVER NORTHERN MONTANA AND SOUTHERN CANADA...WHILE THE
ECMWF IS FURTHER NORTH AND WEAKER WITH THE LOW. THUS HAVE DECIDED
TO TAKE MY LEAD FROM THE 12Z GFS AND CANADIAN MODELS. THIS PATTERN
ALSO SETS UP FAVORABLE CONDITIONS FOR A WINDY DAY ACROSS THE AREA
ON WEDNESDAY. THE NEARLY STACKED 500/700/850 MB LOW CENTERS JUST
TO OUR NORTH SET UP A DEEP LAYER OF WESTERLY WINDS IN THE 30 TO 45
KNOT RANGE. THIS ALONG WITH STRONG MIXING BEHIND THE COLD FRONT
WILL LEAD STRONG AND GUSTY WESTERLY WINDS ON WEDNESDAY. THESE
DOWNSLOPE WINDS ACROSS THE PLAINS SHOULD FURTHER HELP TO INHIBIT
WIDESPREAD SHOWERS ON WEDNESDAY. HOWEVER... DUE TO THE MOIST FLOW
IT IS HARDER TO RULE OUT SHOWERS IN THE MOUNTAINS.
MODEL CONSENSUS IS FOR THE UPPER LEVEL LOW TO SLIDE TOWARD THE EAST
ON THURSDAY BEFORE BECOMING PICKED UP BY THE NORTHERN STREAM OF
THE JET LATE ON THURSDAY. THIS WILL ALLOW FOR THE FLOW ACROSS THE
REGION TO TURN NORTHERLY DURING THE DAY ON THURSDAY. THIS APPEARS
TO HELP GENERATE SOME FRONTOGENSIS ACROSS THE AREA ALONG WITH
UPSLOPE FLOW ALONG NORTH-FACING FOOTHILLS. THUS HAVE DECIDED TO
CONTINUE TO RAISE POPS ON THURSDAY. HAVE ALSO DECIDED TO LOWER THE
TEMPERATURES A BIT MORE FOR THURSDAY DUE TO COOL 850 MB
TEMPERATURES AND POTENTIAL FOR RAIN SHOWERS KEEPING US EVEN
COOLER.
BY FRIDAY AND INTO SATURDAY MODEL CONSENSUS HAS BEEN GOOD IN
AMPLIFYING THE PATTERN. THE MODELS ARE ALL PRETTY AGGRESSIVE IN
AMPLIFYING A RIDGE OVER THE PACIFIC OCEAN THAT LEADS TO THE
DOWNSTREAM DEVELOPMENT OF A TROUGH OVER CALIFORNIA AND A BUILDING
RIDGE OVER THE SOUTHEAST CONUS. THE ECMWF CANADIAN GEM AND EARLIER
RUNS OF THE GFS ARE IN GOOD AGREEMENT TO SHIFT THE JET STREAM
NORTH OF OUR AREA IN SOUTHWESTERLY FLOW. THIS SENDS A WARM FRONT
NORTH ACROSS OUR AREA ON SATURDAY AND GETS US INTO A POTENTIAL
THUNDERSTORM OR HEAVY RAIN SCENARIO DEPENDING ON THE TRACK OF THE
LOW. THE 12Z RUN OF THE GFS THROWS A WRENCH INTO THIS THINKING AS IT
DEVELOPS A WEAKER LOW AND KEEPS US ON THE COOL SIDE OF THE
JET STREAM. REGARDLESS...THE POTENTIAL EXISTS FOR A WET MEMORIAL
DAY WEEKEND AND MODEL TRENDS WILL NEED TO BE WATCHED TO PIN DOWN
THE DETAILS ON HOW THIS PACIFIC TROUGH WILL EVOLVE. CHURCH
&&
.AVIATION...
VFR CONDITIONS ARE EXPECTED TODAY. CLOUD COVER WILL INCREASE OVER
THE MOUNTAINS LATE THIS AFTERNOON WITH ISOLATED SHOWERS. LOCAL MVFR
CONDITIONS CAN BE EXPECTED NEAR ANY PRECIPITATION ALONG WITH
PARTIAL MOUNTAIN OBSCURATION. SHOWER ACTIVITY WILL DISSIPATE
OVERNIGHT. BORSUM
&&
.PRELIMINARY POINT TEMP/POPS...
MON TUE WED THU FRI SAT SUN
-----------------------------------------------------------
BIL 052/088 058/073 044/061 040/057 042/062 045/069 048/070
10/B 16/T 43/T 24/W 33/W 43/T 43/T
LVM 045/085 050/063 036/055 035/055 034/058 039/067 039/068
12/T 26/T 43/T 35/W 44/W 44/T 43/T
HDN 048/090 056/076 044/063 040/059 042/066 045/073 048/073
10/U 16/T 43/T 24/W 33/W 43/T 33/T
MLS 053/089 060/079 047/065 044/060 043/065 048/071 050/074
00/B 15/T 32/T 24/W 33/W 43/T 33/T
4BQ 050/087 057/081 046/063 043/060 042/065 047/074 052/077
00/U 04/T 43/T 24/W 33/W 42/T 33/T
BHK 046/085 054/080 045/062 042/059 042/062 045/068 053/074
00/B 03/T 42/T 24/W 33/W 43/T 33/T
SHR 045/085 054/076 041/059 039/058 040/065 042/074 044/074
00/U 05/T 53/T 34/W 33/W 42/T 33/T
&&
.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...NONE.
WY...NONE.
&&
$$
WEATHER.GOV/BILLINGS
000
FXUS65 KGGW 202129
AFDGGW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GLASGOW MT
329 PM MDT SUN MAY 20 2012
.SHORT TERM...FOR NORTHEAST MONTANA...TONIGHT THROUGH TUESDAY...
WATER VAPOR IMAGERY AND 500 MB HEIGHT FIELD SHOWS THE SLOW-MOVING
WEATHER PATTERN ACROSS THE CONUS. TROPICAL STORM ALBERTO HAS
WEAKENED SOMEWHAT OFF THE SOUTH CAROLINA COASTLINE...BUT HAS ALSO
SPUN OFF ANOTHER PIECE OF ENERGY AND CIRCULATION WHICH MAY FORM
INTO ANOTHER SEPARATE TROPICAL STORM. A FAIRLY STRONG UPPER LEVEL
RIDGE IS IN PLACE OVER THE REMAINDER OF THE EAST COAST AND NEW
ENGLAND STATES WHILE A MORE SUBTLE AND GENERAL WEAK RIDGE SLOWLY
SLIDES OVER THE SOUTHWEST...INTER-MOUNTAIN WEST...AND NORTHERN
HIGH PLAINS. THE UPPER LEVEL TROUGH PUSHING THROUGH THE MIDDLE
PORTION OF THE COUNTRY CONTINUES TO SPAWN THUNDERSTORMS FROM THE
NORTHERN GREAT LAKES THROUGH THE MID-MISSISSIPPI RIVER VALLEY.
CLOUDINESS AND SOUTHWEST FLOW ALOFT IS BEGINNING TO INCREASE OVER
THE PACIFIC NORTHWEST...PREVIEWING THE NEXT LARGE STORM SYSTEM.
A RELATIVELY QUIET HIGH PRESSURE AT THE SURFACE HAS ALLOWED QUITE
A BIT OF SUNSHINE TO REACH THE SURFACE WITH SOME PARTLY CLOUDY
SKIES OVER SOME OF OUR EASTERN ZONES. TEMPERATURES HAVE REACHED
INTO THE LOWER 70S FOR LOCATIONS NOT NEAR THE INTERNATIONAL BORDER.
ONE MORE DAY OF WARMER TEMPERATURES...CALMER WINDS...AND PARTLY
CLOUDY SKIES WITH A FEW SCATTERED PERIMETER SPRINKLES CAN BE
EXPECTED ON MONDAY. TEMPERATURES WILL CLIMB TO NEAR 10 DEGREES
WARMER THAN TODAY WAS.
MONDAY NIGHT...THE MAIN DYNAMICS BEGIN TO SPIN UP AND DRAMATICALLY
INCREASE CHANCES FOR ACCUMULATING PRECIPITATION AS THE NEXT STORM
SYSTEM TAKES AIM FOR THE NORTHERN ROCKIES AND THE NORTHERN HIGH
PLAINS.
TUESDAY WILL BE THE MAIN CHALLENGE IN THE THE FORECAST. SHORT
TERM MODELS ARE BEGINNING TO COALESCE AROUND A COMMON SOLUTION
SHOWING QUITE A BIT OF MEASURABLE PRECIPITATION MOVING THROUGH OUR
CWA EARLY TUESDAY MORNING THROUGH LATE TUESDAY NIGHT. ALTHOUGH
CONDITIONS WILL BE MUCH MORE FAVORABLE FOR SEVERE WEATHER FURTHER
TO OUR EAST...OVER THE DAKOTAS...SOME SEVERE WEATHER PARAMETERS ARE
SHOWING INDICATIONS OF INCREASED RISK FOR AT LEAST SOME LOW-END
SEVERE WEATHER CONNECTED TO THE MAIN COLD FRONT WHICH IS EXPECTED
TO PASS THROUGH SOMETIME TUESDAY AFTERNOON. CAPE VALUES WILL BE
BETWEEN 200 AND 500 J/KG. LCL AS LOW AS 1700 FT...LIFTED INDEX
VALUES BETWEEN -2 AND -4 WILL ACCOMPANY THE COLD FRONT AND MAY
PROVIDE ENOUGH INSTABILITY TO SET OF SOME MARGINALLY SEVERE
THUNDERSTORMS. FOR NOW...DECIDED TO INCREASE POPS...QPF...AND
DAMAGING WIND WORDING IN THE GRIDS. ALSO INCREASED SURFACE WIND
SPEEDS AND GUSTS GENERALLY ACROSS THE CWA...AND MORE SPECIFICALLY
NEAR THE LITTLE ROCKIES WHERE STRONGER WINDS ALWAYS SEEM TO FUNNEL
DOWN THROUGH THE MALTA SOUTH US-HWY 191 DOT SITE. BMICKELSON
.LONG TERM...TUESDAY NIGHT THROUGH SUNDAY...
ONLY MINOR CHANGES TO ONGOING FORECAST. MODELS CONTINUE WITH
FAIRLY POOR CONSENSUS REGARDING UPPER LOW DIGGING INTO THE GREAT
BASIN THEN LIFTING TOWARD THE NORTHERN PLAINS SOMETIME OVER THE
WEEKEND. INDICATIONS ARE A REASONABLY GOOD CHANCE FOR RAIN
SOMETIME DURING THE PERIOD BUT NO CLEAR INDICATION OF WHEN EXACTLY
THAT WILL OCCUR. CONTINUED WITH THE LOWER CHANCE POPS THROUGH MOST
OF THE EXTENDED PERIOD WITH TEMPERATURES GENERALLY BELOW CLIMO.
EBERT
PREVIOUS LONG TERM DISCUSSION...MODELS CONTINUE TO PLACE THE
UPPER LOW DIFFERENTLY ON WEDNESDAY AND WEDNESDAY NIGHT WITH GFS
FAVORING MONTANA AND ECMWF AND ECMWF PUTTING THE LOW IN
SASKATCHEWAN. BOTH MODELS HAVE EASTERN MONTANA IN A DRY SLOT FOR
AT LEAST PART OF THE DAY WHICH WILL ALLOW FOR DAYTIME HEATING TO
DESTABILIZE THE ATMOSPHERE. MAY SEE SOME SHOWERS AND THUNDERSTORMS
DEVELOP AS A RESULT. WILL MENTION A SLIGHT CHANCE FOR NOW.
THE MODEL DIFFERENCES CONTINUE WEDNESDAY NIGHT AND THURSDAY WITH
THE ECMWF AND GEM KEEPING THE UPPER LOW IN SASKATCHEWAN AND DRY
SLOT OVER EASTERN MONTANA WHILE THE GFS TRACKS ITS UPPER LOW INTO
NORTH DAKOTA AND MANITOBA AND BRINGS WRAP AROUND PRECIP THROUGH
EASTERN MONTANA. WILL MAINTAIN A CHANCE OF SHOWERS GIVEN THE UNCERTAINTY.
FRIDAY AND SATURDAY...THE NEXT UPPER LOW DIGS SOUTH INTO NORTHERN
CALIFORNIA WITH RIDGE TO THE EAST. MONTANA WILL BE IN A SOUTHWEST
FLOW ALOFT. ALL THE MODELS DEPICT A PERIOD OF OVERRUNNING MOISTURE
AHEAD OF A WARM OR OCCLUDED FRONT AT SOME POINT FRIDAY AND
SATURDAY. WILL MAINTAIN A CHANCE OF SHOWERS FOR NOW.
THE ECMWF AND GEM WANT TO LIFT THIS LOW NORTH ACROSS WESTERN
MONTANA NEXT SUNDAY WHILE THE GFS KEEPS THE LOW IN CALIFORNIA.
WILL MAINTAIN A CHANCE OF SHOWERS FOR NOW GIVEN THE MODEL
DIFFERENCES. FORRESTER
&&
.AVIATION...
VFR. WILL SEE MID LEVEL CLOUDS AT TIMES OVERNIGHT. SOUTHEAST WINDS
WILL TURN NORTHWEST MONDAY MORNING FOLLOWING A WEAK FRONTAL
PASSAGE.
&&
.GLASGOW WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
WEATHER.GOV/GLASGOW
000
FXUS65 KTFX 202111
AFDTFX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
311 PM MDT SUN MAY 20 2012
.DISCUSSION...
TONIGHT THROUGH TUESDAY...AN UPPER LEVEL RIDGE OF HIGH PRESSURE
WILL REMAIN OVER THE TFX CWA TONIGHT...KEEPING OVERNIGHT LOWS
ABOUT 5 TO 10 DEGREES WARMER THAN NORMAL. HOWEVER...A WEAK
DISTURBANCE WILL MOVE OVER THE TOP OF THE RIDGE...POSSIBLY
BRINGING ISOLATED SHOWERS TO THE AREA...ESPECIALLY OVER THE
MOUNTAINS AND ALONG THE HI-LINE. AN UPPER LEVEL TROUGH OF LOW
PRESSURE WILL THEN MOVE INTO THE PACIFIC NORTHWEST MONDAY INTO
MONDAY NIGHT...BRINGING AN INCREASINGLY MOIST AND UNSTABLE
SOUTHWESTERLY FLOW ALOFT TO THE AREA. AS A RESULT THE CHANCE FOR
SHOWERS WILL INCREASE AS WELL ACROSS THE AREA. A COLD FRONT WILL
ALSO MOVE INTO THE AREA DURING THE DAY ON MONDAY TO COMBINE WITH
WEAK TO MODERATE INSTABILITY FOR A CHANCE OF THUNDERSTORMS.
TEMPERATURES AHEAD OF THIS COLD FRONT WILL REMAIN AROUND 10
DEGREES ABOVE NORMAL MONDAY THROUGH MONDAY NIGHT. THE COLD FRONT
WILL GRADUALLY MOVE ACROSS THE AREA MONDAY NIGHT THROUGH TUESDAY
AS A SHORTWAVE TROUGH EJECTS FROM THE MAIN UPPER LEVEL TROUGH.
HOWEVER...THE CHANCE FOR SHOWERS AND THUNDERSTORMS WILL DECREASE
DURING THE DAY ON TUESDAY AS BREEZY WESTERLY DOWNSLOPE WINDS
DEVELOP IN THE WAKE OF THE COLD FRONT...AS TEMPERATURES FALL BACK
CLOSER TO NORMAL. COULSTON
TUESDAY NIGHT THROUGH SUNDAY...AS HAS BEEN ADVERTISED IT STILL
LOOKS LIKE A COOL AND UNSETTLED PERIOD. THE FIRST PROBLEM TO DEAL
WITH IS WHERE AN UPPER LOW WILL BE ON WEDNESDAY. AS HAS BEEN THE
CASE AT LEAST SINCE YESTERDAY THE GFS MODEL HAS THE UPPER LOW
OVER NORTHEAST MONTANA WITH PRECIPITATION SPREADING SOUTH OVER
MUCH OF THE FORECAST AREA IN THE NORTHERLY FLOW ALOFT ON THE
BACKSIDE OF THE UPPER LOW. OTHER MODELS KEEP THE UPPER LOW IN
CANADA ALONG WITH MOST OF THE ASSOCIATED PRECIPITATION. OTHER
MODEL RUNS OF THE GFS SUGGEST THE LATEST GFS IS OFF THE MARK SO
WILL GO WITH A DRIER FORECAST. MEANWHILE A STRONG UPPER LOW OFF
THE B.C. COAST ON WEDNESDAY IS FORECAST TO DRIVE SOUTHEAST TO
NEAR THE NORTHERN CALIFORNIA COAST BY LATE THURSDAY NIGHT. IN
RESPONSE SOUTHERLY FLOW ALOFT AND MOISTURE INCREASE OVER THE
FORECAST AREA. THIS MOISTURE WILL INTERACT WITH A A COOLER
CANADIAN AIRMASS WHICH WILL SPREAD SOUTH THURSDAY. THIS WILL
RESULT IN AT LEAST AREAS OF RAIN IF NOT WIDESPREAD RAIN THURSDAY
NIGHT WHICH COULD LAST AT LEAST INTO THE EARLY PART OF THE
HOLIDAY WEEKEND. THE GFS IS SLOWER THAN THE GEM AND ECMWF MODELS
WITH TRENDS MENTIONED ABOVE..HOLDING OFF ON THE MORE WIDESPREAD
PRECIPITATION UNTIL FRIDAY. SINCE THE GEM AND ECMWF ARE MORE LIKE
ONE ANOTHER THAN EITHER IS WITH THE GFS WILL GO WITH A FASTER
DEVELOPMENT OF PRECIPITATION. THERE IS UNCERTAINTY WITH HOW LOW
SNOW LEVELS WILL GO BUT THINK THERE WILL BE SNOW IN THE
MOUNTAINS. IN FACT THE NORTHERN PLAINS COULD EVEN SEE A MIX OF
SNOW AND RAIN IF NOT ALL SNOW BY EARLY FRIDAY. BLANK
&&
.AVIATION...
UPDATED 1725Z.
VFR CONDITIONS EXPECTED AS HIGH PRESSURE RIDGE MOVES INTO MONTANA
THIS AFTN. SMALL AREA OF MOISTURE EMBEDDED IN WESTERLY FLOW ALOFT
WILL BRING SHORT-LIVED ISOLATED SHOWERS AND A THUNDERSTORM OR TWO
OVER SOUTHWEST MT LATER THIS AFTN...WITH CONVECTIVE ACTIVITY
DISSIPATING AROUND SUNSET. WINDS REMAINING LIGHT THROUGH THIS EVE.
WARANAUSKAS
&&
.PRELIMINARY POINT TEMPS/POPS...
GTF 49 79 54 64 / 10 30 60 60
CTB 44 72 50 61 / 20 30 50 40
HLN 46 82 52 63 / 10 30 50 60
BZN 40 82 49 63 / 10 30 40 60
WEY 31 73 36 53 / 10 20 30 70
DLN 43 80 49 61 / 10 30 40 60
HVR 46 79 56 67 / 20 10 50 60
LWT 44 78 52 62 / 10 30 40 60
&&
.TFX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...COULSTON
LONG TERM...BLANK
AVIATION...WARANAUSKAS
WEATHER.GOV/GREATFALLS
000
FXUS65 KMSO 202035
AFDMSO
Area Forecast Discussion
National Weather Service Missoula MT
235 PM MDT Sun May 20 2012
.DISCUSSION...
Temperatures will remain fairly mild tonight, as cloud cover
increases ahead of a storm system to arrive on Monday.
A big pattern change will occur at the beginning of the week with
a strong pacific low pressure system tracking across the
northwest. An associated cold front will begin to affect
northwestern Montana Monday morning/early afternoon with light
precipitation and thick clouds...which will keep high
temperatures a few degrees below normal. The cold front will
slowly move to the southeast allowing valley locations from Missoula
south and east to warm into the mid 70s. The atmosphere is
expected to be very unstable ahead of the front so brief heavy
rain and the possibility for thunderstorms will not be out of the
question. Once the front pushes through much cooler air will move
in overnight Monday and early Tuesday morning. Some of the highest mountain
locations could see some snow showers...but no heavy accumulations
are expected. Valley locations throughout western Montana and
central Idaho will still have some off and on light rain showers with
high temperatures only reaching the mid 50s.
Confidence is high that an active pattern with below average
temperatures will dominate the western US through this week. There
will also be high chances for showers this week, though the placement
and amounts are still uncertain. If your plans take you into the
high terrain this week, be prepared for high mountain snowfall and
cool temperatures. Current indications point to the potential for
the cool and wet pattern to continue through Memorial Day weekend.
&&
.AVIATION...
Clouds will increase and lower across the northern Rockies during
the next 24 hours...as a storm system bears down on the region.
Terrain obscurations will become more numerous after 21/0600Z due
to increase in rain shower activity. Winds near the ground are
anticipated to remain fairly weak during this time.
&&
.MSO WATCHES/WARNINGS/ADVISORIES...
MT...None.
ID...None.
&&
$$
dz/lr/jk
Aviation...dz
000
FXUS65 KTFX 201734
AFDTFX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
1125 AM MDT SUN MAY 20 2012
.UPDATE...
ONLY UPDATE FOR THIS MORNING IS TO ADD SLIGHT CHANCE OF THUNDER TO
SOUTHWEST MONTANA FOR THIS AFTERNOON AND THIS EVENING. FORECAST
MODELS INDICATE AT LEAST SOME SLIGHT INSTABILITY DEVELOPING
THEN...AND IF ANY ISOLATED CELLS DEVELOP...THERE IS CERTAINLY A
POSSIBILITY FOR A THUNDERSTORM AS WELL. REMAINDER OF TODAYS
FORECAST IS IN GOOD SHAPE WITH INCREASING CLOUDS AND HIGHS OF 5
TO 10 DEGREES WARMER THAN NORMAL. COULSTON
&&
.AVIATION...
UPDATED 1725Z.
VFR CONDITIONS EXPECTED AS HIGH PRESSURE RIDGE MOVES INTO MONTANA
THIS AFTN. SMALL AREA OF MOISTURE EMBEDDED IN WESTERLY FLOW ALOFT
WILL BRING SHORT-LIVED ISOLATED SHOWERS AND A THUNDERSTORM OR TWO
OVER SOUTHWEST MT LATER THIS AFTN...WITH CONVECTIVE ACTIVITY
DISSIPATING AROUND SUNSET. WINDS REMAINING LIGHT THROUGH THIS EVE.
WARANAUSKAS
&&
.PREV DISCUSSION...
/ISSUED 353 AM MDT SUN MAY 20 2012/
TODAY THROUGH TUESDAY...MAINLY CLEAR SKIES ARE EXPECTED THIS MORNING
AS A WEAK UPPER-LEVEL RIDGE MOVES OVER THE AREA. WEAK INSTABILITY
MAY ALLOW FOR ISOLATED SHOWERS OVER HIGHER TERRAIN THIS AFTERNOON SO
HAVE INCREASED POPS TO SLIGHT CHANCE ALONG THE ROCKY MOUNTAIN FRONT
AND SOUTHWEST MOUNTAINS. A WEAK BOUNDARY WILL PROPAGATE THROUGH THE
AREA LATE TONIGHT WITH BEST CHANCES FOR SHOWERS ALONG THE ROCKY
MOUNTAIN FRONT AND HI-LINE WHERE EMBEDDED SHORTWAVE ENERGY
ALOFT WILL HELP TO ENHANCE LIFT. MOISTURE AND INSTABILITY WILL
INCREASE DURING THE DAY ON MONDAY AS NEXT TROUGH OF LOW PRESSURE AND
SURFACE COLD FRONT MOVES INTO THE PACIFIC NORTHWEST. BEST CHANCES
FOR SHOWERS AND THUNDERSTORMS WILL BE OVER THE HIGHER
TERRAIN...HOWEVER HAVE ALSO INCREASED POPS OVER CENTRAL AND
SOUTHWEST MONTANA...MAINLY ALONG AND WEST OF INTERSTATE 15. SOME
THUNDERSTORMS MAY CONTAIN GUSTY WINDS ON MONDAY AFTERNOON AND
EVENING. HIGH TEMPERATURES ON MONDAY WILL BE AROUND 10 DEGREES ABOVE
SEASONAL AVERAGES. PRECIPITATION WILL BECOME MORE WIDESPREAD AFTER
MIDNIGHT MONDAY NIGHT AS A SURFACE COLD FRONT APPROACHES THE
FORECAST AREA. CURRENT TIMING OF THE FRONT IS EXPECTED FOR TUESDAY
MORNING ALONG THE CONTINENTAL DIVIDE AND THEN PUSH INTO EASTERN
MONTANA BY LATE AFTERNOON. WINDS WILL BECOME WESTERLY AND GUSTY
POST-FRONTAL PASSAGE ON TUESDAY WITH TEMPERATURES FALLING DURING THE
AFTERNOON. MLV
TUESDAY NIGHT THROUGH SUNDAY...AS HAS BEEN ADVERTISED IT STILL LOOKS
LIKE A COOL AND UNSETTLED PERIOD. THE FIRST PROBLEM TO DEAL WITH IS
WHERE AN UPPER LOW WILL BE ON WEDNESDAY. AS HAS BEEN THE CASE AT
LEAST SINCE YESTERDAY THE GFS MODEL HAS THE UPPER LOW OVER NORTHEAST
MONTANA WITH PRECIPITATION SPREADING SOUTH OVER MUCH OF THE FORECAST
AREA IN THE NORTHERLY FLOW ALOFT ON THE BACKSIDE OF THE UPPER LOW.
OTHER MODELS KEEP THE UPPER LOW IN CANADA ALONG WITH MOST OF THE
ASSOCIATED PRECIPITATION. OTHER MODEL RUNS OF THE GFS SUGGEST THE
LATEST GFS IS OFF THE MARK SO WILL GO WITH A DRIER FORECAST.
MEANWHILE A STRONG UPPER LOW OFF THE B.C. COAST ON WEDNESDAY IS
FORECAST TO DRIVE SOUTHEAST TO NEAR THE NORTHERN CALIFORNIA COAST BY
LATE THURSDAY NIGHT. IN RESPONSE SOUTHERLY FLOW ALOFT AND MOISTURE
INCREASE OVER THE FORECAST AREA. THIS MOISTURE WILL INTERACT WITH A
A COOLER CANADIAN AIRMASS WHICH WILL SPREAD SOUTH THURSDAY. THIS
WILL RESULT IN AT LEAST AREAS OF RAIN IF NOT WIDESPREAD RAIN
THURSDAY NIGHT WHICH COULD LAST AT LEAST INTO THE EARLY PART OF THE
HOLIDAY WEEKEND. THE GFS IS SLOWER THAN THE GEM AND ECMWF MODELS
WITH TRENDS MENTIONED ABOVE..HOLDING OFF ON THE MORE WIDESPREAD
PRECIPITATION UNTIL FRIDAY. SINCE THE GEM AND ECMWF ARE MORE LIKE
ONE ANOTHER THAN EITHER IS WITH THE GFS WILL GO WITH A FASTER
DEVELOPMENT OF PRECIPITATION. THERE IS UNCERTAINTY WITH HOW LOW SNOW
LEVELS WILL GO BUT THINK THERE WILL BE SNOW IN THE MOUNTAINS. IN
FACT THE NORTHERN PLAINS COULD EVEN SEE A MIX OF SNOW AND RAIN IF
NOT ALL SNOW BY EARLY FRIDAY. BLANK
&&
.PRELIMINARY POINT TEMPS/POPS...
GTF 74 50 79 51 / 10 10 20 40
CTB 71 45 72 47 / 10 10 20 40
HLN 74 47 81 50 / 10 10 20 40
BZN 73 43 82 47 / 10 10 20 40
WEY 63 37 72 44 / 10 10 20 40
DLN 71 44 80 50 / 10 10 20 40
HVR 74 47 79 51 / 0 10 10 30
LWT 69 44 77 49 / 10 10 20 30
&&
.TFX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...MLV/COULSTON
LONG TERM...BLANK
AVIATION...BLANK
WEATHER.GOV/GREATFALLS
000
FXUS65 KTFX 201600
AFDTFX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
1000 AM MDT SUN MAY 20 2012
.UPDATE...
ONLY UPDATE FOR THIS MORNING IS TO ADD SLIGHT CHANCE OF THUNDER TO
SOUTHWEST MONTANA FOR THIS AFTERNOON AND THIS EVENING. FORECAST
MODELS INDICATE AT LEAST SOME SLIGHT INSTABILITY DEVELOPING
THEN...AND IF ANY ISOLATED CELLS DEVELOP...THERE IS CERTAINLY A
POSSIBILITY FOR A THUNDERSTORM AS WELL. REMAINDER OF TODAYS
FORECAST IS IN GOOD SHAPE WITH INCREASING CLOUDS AND HIGHS OF 5
TO 10 DEGREES WARMER THAN NORMAL. COULSTON
&&
.AVIATION...
UPDATED 1115Z.
EXPECT VFR CONDITIONS. CEILINGS NEAR 10000FT AGL WILL SPREAD EAST
THIS MORNING AND EARLY AFTERNOON. ONCE AGAIN EXPECT WEAK INSTABILITY
THIS AFTERNOON WHICH SHOULD LEAD TO A FEW SHOWERS MAINLY OVER THE
SOUTHWEST AND CENTRAL MOUNTAINS. ALTHOUGH DO NOT EXPECT ANY THUNDER
WITH THE SHOWERS WOULD NOT BE TOTALLY SURPRISED TO SEE AN ISOLATED
THUNDERSTORM. SHOWERS SHOULD END AFTER DARK. WINDS ARE EXPECTED TO
BE GENERALLY LIGHT AND CONFIDENCE IN FORECAST DIRECTIONS IN THE TAFS
IS LOW TO MODERATE. BLANK
&&
.PREV DISCUSSION...
/ISSUED 353 AM MDT SUN MAY 20 2012/
TODAY THROUGH TUESDAY...MAINLY CLEAR SKIES ARE EXPECTED THIS MORNING
AS A WEAK UPPER-LEVEL RIDGE MOVES OVER THE AREA. WEAK INSTABILITY
MAY ALLOW FOR ISOLATED SHOWERS OVER HIGHER TERRAIN THIS AFTERNOON SO
HAVE INCREASED POPS TO SLIGHT CHANCE ALONG THE ROCKY MOUNTAIN FRONT
AND SOUTHWEST MOUNTAINS. A WEAK BOUNDARY WILL PROPAGATE THROUGH THE
AREA LATE TONIGHT WITH BEST CHANCES FOR SHOWERS ALONG THE ROCKY
MOUNTAIN FRONT AND HI-LINE WHERE EMBEDDED SHORTWAVE ENERGY
ALOFT WILL HELP TO ENHANCE LIFT. MOISTURE AND INSTABILITY WILL
INCREASE DURING THE DAY ON MONDAY AS NEXT TROUGH OF LOW PRESSURE AND
SURFACE COLD FRONT MOVES INTO THE PACIFIC NORTHWEST. BEST CHANCES
FOR SHOWERS AND THUNDERSTORMS WILL BE OVER THE HIGHER
TERRAIN...HOWEVER HAVE ALSO INCREASED POPS OVER CENTRAL AND
SOUTHWEST MONTANA...MAINLY ALONG AND WEST OF INTERSTATE 15. SOME
THUNDERSTORMS MAY CONTAIN GUSTY WINDS ON MONDAY AFTERNOON AND
EVENING. HIGH TEMPERATURES ON MONDAY WILL BE AROUND 10 DEGREES ABOVE
SEASONAL AVERAGES. PRECIPITATION WILL BECOME MORE WIDESPREAD AFTER
MIDNIGHT MONDAY NIGHT AS A SURFACE COLD FRONT APPROACHES THE
FORECAST AREA. CURRENT TIMING OF THE FRONT IS EXPECTED FOR TUESDAY
MORNING ALONG THE CONTINENTAL DIVIDE AND THEN PUSH INTO EASTERN
MONTANA BY LATE AFTERNOON. WINDS WILL BECOME WESTERLY AND GUSTY
POST-FRONTAL PASSAGE ON TUESDAY WITH TEMPERATURES FALLING DURING THE
AFTERNOON. MLV
TUESDAY NIGHT THROUGH SUNDAY...AS HAS BEEN ADVERTISED IT STILL LOOKS
LIKE A COOL AND UNSETTLED PERIOD. THE FIRST PROBLEM TO DEAL WITH IS
WHERE AN UPPER LOW WILL BE ON WEDNESDAY. AS HAS BEEN THE CASE AT
LEAST SINCE YESTERDAY THE GFS MODEL HAS THE UPPER LOW OVER NORTHEAST
MONTANA WITH PRECIPITATION SPREADING SOUTH OVER MUCH OF THE FORECAST
AREA IN THE NORTHERLY FLOW ALOFT ON THE BACKSIDE OF THE UPPER LOW.
OTHER MODELS KEEP THE UPPER LOW IN CANADA ALONG WITH MOST OF THE
ASSOCIATED PRECIPITATION. OTHER MODEL RUNS OF THE GFS SUGGEST THE
LATEST GFS IS OFF THE MARK SO WILL GO WITH A DRIER FORECAST.
MEANWHILE A STRONG UPPER LOW OFF THE B.C. COAST ON WEDNESDAY IS
FORECAST TO DRIVE SOUTHEAST TO NEAR THE NORTHERN CALIFORNIA COAST BY
LATE THURSDAY NIGHT. IN RESPONSE SOUTHERLY FLOW ALOFT AND MOISTURE
INCREASE OVER THE FORECAST AREA. THIS MOISTURE WILL INTERACT WITH A
A COOLER CANADIAN AIRMASS WHICH WILL SPREAD SOUTH THURSDAY. THIS
WILL RESULT IN AT LEAST AREAS OF RAIN IF NOT WIDESPREAD RAIN
THURSDAY NIGHT WHICH COULD LAST AT LEAST INTO THE EARLY PART OF THE
HOLIDAY WEEKEND. THE GFS IS SLOWER THAN THE GEM AND ECMWF MODELS
WITH TRENDS MENTIONED ABOVE..HOLDING OFF ON THE MORE WIDESPREAD
PRECIPITATION UNTIL FRIDAY. SINCE THE GEM AND ECMWF ARE MORE LIKE
ONE ANOTHER THAN EITHER IS WITH THE GFS WILL GO WITH A FASTER
DEVELOPMENT OF PRECIPITATION. THERE IS UNCERTAINTY WITH HOW LOW SNOW
LEVELS WILL GO BUT THINK THERE WILL BE SNOW IN THE MOUNTAINS. IN
FACT THE NORTHERN PLAINS COULD EVEN SEE A MIX OF SNOW AND RAIN IF
NOT ALL SNOW BY EARLY FRIDAY. BLANK
&&
.PRELIMINARY POINT TEMPS/POPS...
GTF 74 50 79 51 / 10 10 20 40
CTB 71 45 72 47 / 10 10 20 40
HLN 74 47 81 50 / 10 10 20 40
BZN 73 43 82 47 / 10 10 20 40
WEY 63 37 72 44 / 10 10 20 40
DLN 71 44 80 50 / 10 10 20 40
HVR 74 47 79 51 / 0 10 10 30
LWT 69 44 77 49 / 10 10 20 30
&&
.TFX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...MLV/COULSTON
LONG TERM...BLANK
AVIATION...BLANK
WEATHER.GOV/GREATFALLS
000
FXUS65 KBYZ 201533
AFDBYZ
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BILLINGS MT
933 AM MDT SUN MAY 20 2012
.SHORT TERM...VALID FOR TDY AND MON...
NO UPDATE THIS MORNING. AS EXPECTED...PATCHY FOG HAS ALREADY
DISSIPATED ACROSS THE REGION WITH TEMP/DEWPOINT SPREADS CONTINUING
TO INCREASE. WEAK SHORTWAVE ACTIVITY MOVING THROUGH WESTERN MONTANA
WILL INCREASE CLOUD COVER FROM WEST TO EAST THROUGH THE DAY AND
INCREASE THE POTENTIAL FOR PRECIPITATION ACROSS WESTERN AND
CENTRAL ZONES THIS AFTERNOON AND EVENING. FORECAST CAPE VALUES
ARE NOT TOO IMPRESSIVE WITH LIMITED LOW-LEVEL MOISTURE...AND
EFFECTIVE BULK SHEAR IS ALSO ON THE WEAK SIDE...SO ONLY EXPECTING
A FEW SHOWERS. TEMPS SHOULD BE 5 TO 10 DEGREES WARMER THAN
YESTERDAY WITH 850 MB AND 700 MB TEMPS A FEW DEGREES WARMER...AND
PLENTY OF MIXING EXPECTED. STC
.LONG TERM...VALID FOR TUE...WED...THU...FRI...SAT...
UNSETTLED WEATHER PATTERN FOR THE EXTENDED WITH ENSEMBLE FORECASTS
INDICATING CLIMO POPS OR BETTER FOR JUST ABOUT EVERY PERIOD.
OPERATIONAL MODELS SHOWING A GREAT DEAL OF SPREAD IN STRENGTH AND
TRACK OF THE SEVERAL SYSTEMS IMPACTING THE REGION TUESDAY INTO
EARLY NEXT WEEK...SO LEANING ON THE ENSEMBLE MEAN FOR THE SREF AND
GFS FOR THIS FORECAST PACKAGE.
UPPER TROF DIGS INTO THE AREA TUESDAY WITH A WEAK NEGATIVELY
TILTED STRUCTURE. TROF SETTLES OVER THE AREA WITH CUT OFF LOW
DEVELOPING SOMEWHERE FROM NORTHERN MONTANA TO JUST INSIDE THE
CANADIAN BORDER. PLENTY OF PACIFIC MOISTURE FLOWING THROUGH THIS
SYSTEM ALONG WITH JET SUPPORTED ENERGY SO INCREASED POPS TUESDAY
INTO EARLY WEDNESDAY FOR MOST AREAS...ESPECIALLY WEST OF ROSEBUD
COUNTY. MODELS HITTING THE FOOTHILLS FROM LIVINGSTON TO SHERIDAN
HARDEST WITH THIS SYSTEM. WITH TROF AND UNSETTLED CONDITIONS
COOLED TEMPERATURES FROM THE HIGH SIDE OF GUIDANCE CLOSER TO THE
MIDDLE RANGE.
JET SAGS SOUTH OF THE AREA WEDNESDAY AND THURSDAY KEEPING
TEMPERATURES BELOW SEASONAL LEVELS. MODELS SHOWING HIGH
UNCERTAINTY WITH ANY SPECIFIC UPPER LEVEL ENERGY BUT MEAN TROF
AXIS BECOMES STRETCHED WEST TO EAST ACROSS THE FORECAST AREA
SUPPORTING CLIMO TYPE POPS...WITH HIGHER POPS FOR THE
AFTERNOON/EVENING HOURS WITH BETTER INSTABILITY.
MODELS IN AGREEMENT WITH FLOW ALOFT BECOMING STRONGLY BACKED TO
THE SOUTH ON FRIDAY AS STRONG PACIFIC STORM MOVES INTO CALIFORNIA.
WARMER TEMPERATURES WILL SPREAD NORTHWARD FRIDAY INTO SATURDAY
WITH THIS FLOW. HOWEVER THESE WARMER TEMPERATURES WILL PRODUCE
INSTABILITY THAT WILL COMBINE WITH INCREASINGLY DIVERGENT FLOW
ALOFT TO INCREASE SHOWER AND THUNDERSTORM POTENTIAL. INCREASED
POPS FOR THIS TIME FRAME TO ACCOUNT FOR THIS.
TRACK OF THE UPPER STORM OUT OF CALIFORNIA WILL BE IMPORTANT FOR
WEEKEND WEATHER AS THE OPERATIONAL GFS BRING THIS POTENT SYSTEM
INTO THE SWEET SPOT FOR A WIDESPREAD HEAVY PRECIPITATION EVENT FOR
THE FORECAST AREA...ACROSS NORTHERN WYOMING AND SLOWING INTO THE
WESTERN DAKOTAS. QPF FOR THE 00Z GFS SHOWING WIDESPREAD 2 TO 4
INCH PRECIPITATION AMOUNTS SATURDAY INTO MONDAY. GFS ENSEMBLE MEAN
AND OPERATIONAL ECMWF PUSH THE SYSTEM NORTHWARD ACROSS WESTERN
MONTANA AND INTO CANADA FOR A MUCH DRIER SOLUTION. WILL HAVE TO
WATCH THIS PERIOD CAREFULLY...AND INCREASED POPS TO CLIMATOLOGY
FOR THIS TIME FRAME. CHAMBERS
&&
.AVIATION...
VFR CONDITIONS ARE EXPECTED TODAY. CLOUD COVER WILL INCREASE OVER
THE MOUNTAINS LATE THIS AFTERNOON WITH ISOLATED SHOWERS. LOCAL MVFR
CONDITIONS CAN BE EXPECTED NEAR ANY PRECIPITATION ALONG WITH
PARTIAL MOUNTAIN OBSCURATION. SHOWER ACTIVITY WILL DISSIPATE
OVERNIGHT. BORSUM
&&
.PRELIMINARY POINT TEMP/POPS...
TDY MON TUE WED THU FRI SAT
-------------------------------------------------------
BIL 076 052/088 059/073 043/061 040/060 042/062 045/069
0/B 10/B 15/T 43/T 23/W 33/W 33/T
LVM 074 045/085 050/063 035/055 035/057 034/058 039/067
1/B 12/T 26/T 43/T 34/W 44/W 34/T
HDN 077 048/090 056/076 043/063 040/062 042/066 045/073
0/B 10/U 14/T 43/T 23/W 33/W 32/T
MLS 076 053/089 061/079 047/065 044/063 043/065 048/071
0/B 00/U 13/T 42/T 23/W 33/W 43/T
4BQ 074 050/087 057/081 046/063 043/062 042/065 047/074
0/B 00/U 03/T 43/T 23/W 33/W 32/T
BHK 071 046/085 056/080 046/062 042/062 041/062 045/068
0/B 00/B 03/T 42/T 23/W 33/W 43/T
SHR 073 045/085 054/076 040/059 039/059 039/065 042/074
0/B 00/U 04/T 53/T 33/W 33/W 32/T
&&
.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...NONE.
WY...NONE.
&&
$$
WEATHER.GOV/BILLINGS
000
FXUS65 KGGW 201517 AAA
AFDGGW
AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE GLASGOW MT
917 AM MDT SUN MAY 20 2012
.SHORT TERM...FOR NORTHEAST MONTANA...TODAY THROUGH TUESDAY...
MADE SOME VERY MINOR ADJUSTMENTS FOR THE UPDATE THIS
MORNING....MAINLY FOR TEMPERATURES AND TO ADD A SMALL AREA OF
SPRINKLES FOLLOWING RADAR REFLECTIVITY TRENDS THIS MORNING.
ALTHOUGH...IT MAY BE ONLY LIGHT VIRGA RAIN SHOWERS. BMICKELSON
PREVIOUS SHORT TERM DISCUSSION...A WEAK UPPER LEVEL RIDGE AXIS
WORKS ITS WAY ACROSS MONTANA TODAY AND MONDAY...WHICH WILL
MAINTAIN A WEST TO NORTHWEST FLOW ALOFT OVER NORTHEAST MONTANA. A
SURFACE TROUGH FORMING IN THE LEE OF THE CANADIAN ROCKIES WILL
CREATE A WEAK SOUTHERLY SURFACE BREEZE TODAY. THIS WILL BEGIN TO
TAP INTO THE GREAT BASIN DESERT AIR THAT BEGINS TO CREEP NORTH
INTO SOUTHERN MONTANA. THIS RIDGING WILL INCREASE 1000MB-500MB
THICKNESS HEIGHTS FROM AROUND 550DM ON SATURDAY EVENING TO AROUND
560DM THIS EVENING. THEREFORE HIGHS TODAY SHOULD BECOME AROUND 10
DEGREES WARMER THAN SATURDAY...WHICH WAS SLIGHTLY COOLER THAN
NORMAL. EXPECT MOST HIGHS IN THE 70S TODAY.
TONIGHT...A PACIFIC STORM FEEDS MOISTURE OVER THE TOP OF THE
RIDGE. SOME OF THIS MOISTURE IN THE FORM OF SKY COVER SPREADS
OVER THE MONTANA PRAIRIE WITH THE EXPANDING SURFACE TROUGH. THE
MODELS SHOW A WEAK WARM FRONT MOVING IN FROM THE SW. THE GFS
CREATES A FEW AREAS OF LIMITED QPF AFTER MIDNIGHT. SO WILL
MAINTAIN THE INHERITED SPRINKLES.
MONDAY...WARM AIR FROM THE SW SURGES INTO EASTERN MONTANA PUSHING
MOST OF THE CLOUD COVER TO THE EAST. 1000MB-500MB THICKNESS
HEIGHTS CORRESPONDINGLY RAMP UP TO AROUND 570DM. EXPECT MOST
TEMPERATURES TO RISE INTO THE 80S...AND UPPER 70S ALONG THE
CANADIAN BORDER.
MONDAY NIGHT AND TUESDAY...THE RIDGE AXIS SHIFTS EAST OF NEMONT.
THIS WILL BRING IN A SOUTHWESTERLY FLOW ALOFT...CHANNELING
MOISTURE INTO THE REGION. A PACIFIC STORM THAT SLAMS INTO THE
NORTHWEST COAST ON MONDAY WILL CONTINUE SENDING MOISTURE INTO THE
NORTHERN ROCKIES AND OVER THE DIVIDE...REACHING NEMONT MONDAY
EVENING. AN ASSOCIATED DIFFUSE COLD FRONT SHOULD INITIATE RAIN
SHOWERS ALONG WITH THUNDERSTORMS. TIMING IS SUCH THAT THE
STRONGEST THUNDERSTORMS WILL FORM OVER CENTRAL MONTANA MONDAY
AFTERNOON. THE STORMS COULD MOSTLY LOSE MOST OF THEIR PUNCH BY
MONDAY EVENING WHEN THEY DRIFT INTO NEMONT. THEN ON TUESDAY A
STRONGER...MORE DISTINCT...COLD FRONT WILL INITIATE ANOTHER ROUND OF
THUNDERSTORMS. BUT THE BEST INSTABILITY WILL BE TO OUR EAST IN THE
AFTERNOON. IN ANY CASE THERE WILL BE ABUNDANT QPF ASSOCIATED WITH
THESE CONVECTIVE SHOWERS. THE UPPER TROUGH BECOME A LONG WAVE BY
THE END OF THE SHORT TERM. THE STORM GIVES APPEARANCES OF BECOMING
ORGANIZED INTO A STACKED BUT NOT NECESSARILY TIGHT CYCLONE WITH
SOME DRY SLOTTING POSSIBLE. WITH FALLING THICKNESS HEIGHTS AND
INCREASED CLOUD COVER TEMPERATURES ON TUESDAY WILL TREND BACK DOWN
TO AROUND NORMAL. SCT
.LONG TERM...TUESDAY NIGHT THROUGH SUNDAY...
MODELS CONTINUE TO PLACE THE UPPER LOW DIFFERENTLY ON WEDNESDAY
AND WEDNESDAY NIGHT WITH GFS FAVORING MONTANA AND ECMWF AND ECMWF PUTTING
THE LOW IN SASKATCHEWAN. BOTH MODELS HAVE EASTERN MONTANA IN A DRY
SLOT FOR AT LEAST PART OF THE DAY WHICH WILL ALLOW FOR DAYTIME
HEATING TO DESTABILIZE THE ATMOSPHERE. MAY SEE SOME SHOWERS AND
THUNDERSTORMS DEVELOP AS A RESULT. WILL MENTION A SLIGHT CHANCE FOR
NOW.
THE MODEL DIFFERENCES CONTINUE WEDNESDAY NIGHT AND THURSDAY WITH
THE ECMWF AND GEM KEEPING THE UPPER LOW IN SASKATCHEWAN AND DRY
SLOT OVER EASTERN MONTANA WHILE THE GFS TRACKS ITS UPPER LOW INTO
NORTH DAKOTA AND MANITOBA AND BRINGS WRAP AROUND PRECIP THROUGH
EASTERN MONTANA. WILL MAINTAIN A CHANCE OF SHOWERS GIVEN THE UNCERTAINTY.
FRIDAY AND SATURDAY...THE NEXT UPPER LOW DIGS SOUTH INTO NORTHERN
CALIFORNIA WITH RIDGE TO THE EAST. MONTANA WILL BE IN A SOUTHWEST
FLOW ALOFT. ALL THE MODELS DEPICT A PERIOD OF OVERRUNNING MOISTURE
AHEAD OF A WARM OR OCCLUDED FRONT AT SOME POINT FRIDAY AND
SATURDAY. WILL MAINTAIN A CHANCE OF SHOWERS FOR NOW.
THE ECMWF AND GEM WANT TO LIFT THIS LOW NORTH ACROSS WESTERN
MONTANA NEXT SUNDAY WHILE THE GFS KEEPS THE LOW IN CALIFORNIA.
WILL MAINTAIN A CHANCE OF SHOWERS FOR NOW GIVEN THE MODEL
DIFFERENCES. FORRESTER
&&
.AVIATION...
VFR. WILL SEE MID LEVEL CLOUDS AT TIMES TODAY AND TONIGHT.
SOUTHEAST WINDS 5 TO 10 KNOTS WILL DEVELOP BY 18Z AND TURN TO THE
EAST THIS EVENING.
&&
.GLASGOW WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
WEATHER.GOV/GLASGOW
000
FXUS65 KTFX 200953
AFDTFX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
353 AM MDT SUN MAY 20 2012
.DISCUSSION...
TODAY THROUGH TUESDAY...MAINLY CLEAR SKIES ARE EXPECTED THIS MORNING
AS A WEAK UPPER-LEVEL RIDGE MOVES OVER THE AREA. WEAK INSTABILITY
MAY ALLOW FOR ISOLATED SHOWERS OVER HIGHER TERRAIN THIS AFTERNOON SO
HAVE INCREASED POPS TO SLIGHT CHANCE ALONG THE ROCKY MOUNTAIN FRONT
AND SOUTHWEST MOUNTAINS. A WEAK BOUNDARY WILL PROPAGATE THROUGH THE
AREA LATE TONIGHT WITH BEST CHANCES FOR SHOWERS ALONG THE ROCKY
MOUNTAIN FRONT AND HI-LINE WHERE EMBEDDED SHORTWAVE ENERGY
ALOFT WILL HELP TO ENHANCE LIFT. MOISTURE AND INSTABILITY WILL
INCREASE DURING THE DAY ON MONDAY AS NEXT TROUGH OF LOW PRESSURE AND
SURFACE COLD FRONT MOVES INTO THE PACIFIC NORTHWEST. BEST CHANCES
FOR SHOWERS AND THUNDERSTORMS WILL BE OVER THE HIGHER
TERRAIN...HOWEVER HAVE ALSO INCREASED POPS OVER CENTRAL AND
SOUTHWEST MONTANA...MAINLY ALONG AND WEST OF INTERSTATE 15. SOME
THUNDERSTORMS MAY CONTAIN GUSTY WINDS ON MONDAY AFTERNOON AND
EVENING. HIGH TEMPERATURES ON MONDAY WILL BE AROUND 10 DEGREES ABOVE
SEASONAL AVERAGES. PRECIPITATION WILL BECOME MORE WIDESPREAD AFTER
MIDNIGHT MONDAY NIGHT AS A SURFACE COLD FRONT APPROACHES THE
FORECAST AREA. CURRENT TIMING OF THE FRONT IS EXPECTED FOR TUESDAY
MORNING ALONG THE CONTINENTAL DIVIDE AND THEN PUSH INTO EASTERN
MONTANA BY LATE AFTERNOON. WINDS WILL BECOME WESTERLY AND GUSTY
POST-FRONTAL PASSAGE ON TUESDAY WITH TEMPERATURES FALLING DURING THE
AFTERNOON. MLV
TUESDAY NIGHT THROUGH SUNDAY...AS HAS BEEN ADVERTISED IT STILL LOOKS
LIKE A COOL AND UNSETTLED PERIOD. THE FIRST PROBLEM TO DEAL WITH IS
WHERE AN UPPER LOW WILL BE ON WEDNESDAY. AS HAS BEEN THE CASE AT
LEAST SINCE YESTERDAY THE GFS MODEL HAS THE UPPER LOW OVER
NORTHEAST MONTANA WITH PRECIPITATION SPREADING SOUTH OVER MUCH OF THE
FORECAST AREA IN THE NORTHERLY FLOW ALOFT ON THE BACKSIDE OF THE
UPPER LOW. OTHER MODELS KEEP THE UPPER LOW IN CANADA ALONG WITH MOST
OF THE ASSOCIATED PRECIPITATION. OTHER MODEL RUNS OF THE GFS SUGGEST
THE LATEST GFS IS OFF THE MARK SO WILL GO WITH A DRIER FORECAST.
MEANWHILE A STRONG UPPER LOW OFF THE B.C. COAST ON WEDNESDAY IS
FORECAST TO DRIVE SOUTHEAST TO NEAR THE NORTHERN CALIFORNIA COAST BY
LATE THURSDAY NIGHT. IN RESPONSE SOUTHERLY FLOW ALOFT AND MOISTURE
INCREASE OVER THE FORECAST AREA. THIS MOISTURE WILL INTERACT WITH A
A COOLER CANADIAN AIRMASS WHICH WILL SPREAD SOUTH THURSDAY. THIS
WILL RESULT IN AT LEAST AREAS OF RAIN IF NOT WIDESPREAD RAIN
THURSDAY NIGHT WHICH COULD LAST AT LEAST INTO THE EARLY PART OF THE
HOLIDAY WEEKEND. THE GFS IS SLOWER THAN THE GEM AND ECMWF MODELS
WITH TRENDS MENTIONED ABOVE..HOLDING OFF ON THE MORE WIDESPREAD
PRECIPITATION UNTIL FRIDAY. SINCE THE GEM AND ECMWF ARE MORE LIKE
ONE ANOTHER THAN EITHER IS WITH THE GFS WILL GO WITH A FASTER
DEVELOPMENT OF PRECIPITATION. THERE IS UNCERTAINTY WITH HOW LOW SNOW
LEVELS WILL GO BUT THINK THERE WILL BE SNOW IN THE MOUNTAINS. IN
FACT THE NORTHERN PLAINS COULD EVEN SEE A MIX OF SNOW AND RAIN IF
NOT ALL SNOW BY EARLY FRIDAY. BLANK
&&
.AVIATION...
UPDATED 0500Z.
EXPECT VFR CONDITIONS AND LIGHT WINDS THROUGHOUT THE TAF PERIOD. FEW
TO SCATTERED OVERNIGHT CLOUDS WILL GIVE WAY TO INCREASING AFTERNOON
CLOUDS TOMORROW. BROKEN CEILINGS AND A FEW SHOWERS WILL ONCE AGAIN
BE POSSIBLE ACROSS CENTRAL MONTANA. CONDITIONS WILL IMPROVE TOMORROW
NIGHT AHEAD OF A LARGE SYSTEM THAT WILL IMPACT THE REGION LATE MON.
&&
.PRELIMINARY POINT TEMPS/POPS...
GTF 74 50 79 51 / 10 10 20 40
CTB 71 45 72 47 / 10 10 20 40
HLN 74 47 81 50 / 10 10 20 40
BZN 73 43 82 47 / 10 10 20 40
WEY 63 37 72 44 / 10 20 20 50
DLN 71 44 80 50 / 10 10 20 40
HVR 74 47 79 51 / 0 10 10 30
LWT 69 44 77 49 / 10 10 20 30
&&
.TFX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
WEATHER.GOV/GREATFALLS
000
FXUS65 KMSO 200945
AFDMSO
Area Forecast Discussion
National Weather Service Missoula MT
345 AM MDT Sun May 20 2012
.DISCUSSION...Westerly flow aloft will remain over the Northern
Rockies today. An approaching area of low pressure off the Pacific
Northwest coastline will begin to pump moisture into the region in
the form of mid and high level cloud cover. Enough lift may be
present through this moisture to produce sprinkles across the
region by this afternoon. Unfortunately, increasing cloud cover
will likely obscure the eclipse that will occur this evening.
Confidence remains high that a cold front will track through the
region Monday evening. Ahead of this feature, light precipitation
will begin across northwest Montana Monday morning and will increase in
intensity by afternoon. As the cold front tracks southeast Monday
evening, so will precipitation. The heaviest precipitation amounts
are expected in north central Idaho and northwest Montana.
However, most all locations will see measurable precipitation. In
addition, thunderstorms are likely along the front Monday evening.
Temperatures and snow levels will lower by Tuesday morning,
leading to a much cooler day with temperatures well below normal
and light snow possible in the higher terrain. Showery conditions
will persist as the upper level trough remains over the region. In
addition, breezy west winds can be expected all day Tuesday, which
could lead to choppy conditions on area lakes.
Wednesday through Saturday...Wednesday will be the coolest day of
May so far with temperatures for most locations staying in the
40s for the majority of the day. Lingering showers are expected to
last through Wednesday night behind the exiting trough. On the
heels of this trough will be another digging along the west coast
pumping more moisture into the Northern Rockies through the
weekend. The timing of the next lows departure is still in
question but current timing puts it over the top of western
Montana Sunday and finally exiting the region Monday afternoon.
&&
.AVIATION...Mid and high level cloud cover will increase over the
region this morning, leading to areas of obscured terrain. A few very
light showers are possible this afternoon and evening but will
cause minimal impacts to aviation. Winds will increase slightly
this afternoon from the west, particularly across western Montana.
&&
.MSO WATCHES/WARNINGS/ADVISORIES...
MT...None.
ID...None.
&&
$$
jp/ml/jp
000
FXUS65 KGGW 200930
AFDGGW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GLASGOW MT
330 AM MDT SUN MAY 20 2012
.SHORT TERM...FOR NORTHEAST MONTANA...TODAY THROUGH TUESDAY...
A WEAK UPPER LEVEL RIDGE AXIS WORKS ITS WAY ACROSS MONTANA TODAY
AND MONDAY...WHICH WILL MAINTAIN A WEST TO NORTHWEST FLOW ALOFT
OVER NORTHEAST MONTANA. A SURFACE TROUGH FORMING IN THE LEE OF
THE CANADIAN ROCKIES WILL CREATE A WEAK SOUTHERLY SURFACE BREEZE
TODAY. THIS WILL BEGIN TO TAP INTO THE GREAT BASIN DESERT AIR THAT
BEGINS TO CREEP NORTH INTO SOUTHERN MONTANA. THIS RIDGING WILL
INCREASE 1000MB-500MB THICKNESS HEIGHTS FROM AROUND 550DM ON
SATURDAY EVENING TO AROUND 560DM THIS EVENING. THEREFORE HIGHS
TODAY SHOULD BECOME AROUND 10 DEGREES WARMER THAN SATURDAY...WHICH
WAS SLIGHTLY COOLER THAN NORMAL. EXPECT MOST HIGHS IN THE 70S
TODAY.
TONIGHT...A PACIFIC STORM FEEDS MOISTURE OVER THE TOP OF THE
RIDGE. SOME OF THIS MOISTURE IN THE FORM OF SKY COVER SPREADS
OVER THE MONTANA PRAIRIE WITH THE EXPANDING SURFACE TROUGH. THE
MODELS SHOW A WEAK WARM FRONT MOVING IN FROM THE SW. THE GFS
CREATES A FEW AREAS OF LIMITED QPF AFTER MIDNIGHT. SO WILL
MAINTAIN THE INHERITED SPRINKLES.
MONDAY...WARM AIR FROM THE SW SURGES INTO EASTERN MONTANA PUSHING
MOST OF THE CLOUD COVER TO THE EAST. 1000MB-500MB THICKNESS
HEIGHTS CORRESPONDINGLY RAMP UP TO AROUND 570DM. EXPECT MOST
TEMPERATURES TO RISE INTO THE 80S...AND UPPER 70S ALONG THE
CANADIAN BORDER.
MONDAY NIGHT AND TUESDAY...THE RIDGE AXIS SHIFTS EAST OF NEMONT.
THIS WILL BRING IN A SOUTHWESTERLY FLOW ALOFT...CHANNELING
MOISTURE INTO THE REGION. A PACIFIC STORM THAT SLAMS INTO THE
NORTHWEST COAST ON MONDAY WILL CONTINUE SENDING MOISTURE INTO THE
NORTHERN ROCKIES AND OVER THE DIVIDE...REACHING NEMONT MONDAY
EVENING. AN ASSOCIATED DIFFUSE COLD FRONT SHOULD INITIATE RAIN
SHOWERS ALONG WITH THUNDERSTORMS. TIMING IS SUCH THAT THE
STRONGEST THUNDERSTORMS WILL FORM OVER CENTRAL MONTANA MONDAY
AFTERNOON. THE STORMS COULD MOSTLY LOSE MOST OF THEIR PUNCH BY
MONDAY EVENING WHEN THEY DRIFT INTO NEMONT. THEN ON TUESDAY A
STRONGER...MORE DISTINCT...COLD FRONT WILL INITIATE ANOTHER ROUND OF
THUNDERSTORMS. BUT THE BEST INSTABILITY WILL BE TO OUR EAST IN THE
AFTERNOON. IN ANY CASE THERE WILL BE ABUNDANT QPF ASSOCIATED WITH
THESE CONVECTIVE SHOWERS. THE UPPER TROUGH BECOME A LONG WAVE BY
THE END OF THE SHORT TERM. THE STORM GIVES APPEARANCES OF BECOMING
ORGANIZED INTO A STACKED BUT NOT NECESSARILY TIGHT CYCLONE WITH
SOME DRY SLOTTING POSSIBLE. WITH FALLING THICKNESS HEIGHTS AND
INCREASED CLOUD COVER TEMPERATURES ON TUESDAY WILL TREND BACK DOWN
TO AROUND NORMAL. SCT
.LONG TERM...TUESDAY NIGHT THROUGH SUNDAY...
MODELS CONTINUE TO PLACE THE UPPER LOW DIFFERENTLY ON WEDNESDAY
AND WEDNESDAY NIGHT WITH GFS FAVORING MONTANA AND ECMWF AND ECMWF
PUTTING THE LOW IN SASKATCHEWAN. BOTH MODELS HAVE EASTERN
MONTANA IN A DRY SLOT FOR AT LEAST PART OF THE DAY WHICH WILL
ALLOW FOR DAYTIME HEATING TO DESTABILIZE THE ATMOSPHERE. MAY SEE
SOME SHOWERS AND THUNDERSTORMS DEVELOP AS A RESULT. WILL MENTION A
SLIGHT CHANCE FOR NOW.
THE MODEL DIFFERENCES CONTINUE WEDNESDAY NIGHT AND THURSDAY WITH
THE ECMWF AND GEM KEEPING THE UPPER LOW IN SASKATCHEWAN AND DRY
SLOT OVER EASTERN MONTANA WHILE THE GFS TRACKS ITS UPPER LOW INTO
NORTH DAKOTA AND MANITOBA AND BRINGS WRAP AROUND PRECIP THROUGH
EASTERN MONTANA. WILL MAINTAIN A CHANCE OF SHOWERS GIVEN THE
UNCERTAINTY.
FRIDAY AND SATURDAY...THE NEXT UPPER LOW DIGS SOUTH INTO NORTHERN
CALIFORNIA WITH RIDGE TO THE EAST. MONTANA WILL BE IN A SOUTHWEST
FLOW ALOFT. ALL THE MODELS DEPICT A PERIOD OF OVERRUNNING MOISTURE
AHEAD OF A WARM OR OCCLUDED FRONT AT SOME POINT FRIDAY AND
SATURDAY. WILL MAINTAIN A CHANCE OF SHOWERS FOR NOW.
THE ECMWF AND GEM WANT TO LIFT THIS LOW NORTH ACROSS WESTERN
MONTANA NEXT SUNDAY WHILE THE GFS KEEPS THE LOW IN CALIFORNIA.
WILL MAINTAIN A CHANCE OF SHOWERS FOR NOW GIVEN THE MODEL
DIFFERENCES. FORRESTER
&&
.AVIATION...
VFR. WILL SEE MID LEVEL CLOUDS AT TIMES TODAY AND TONIGHT.
SOUTHEAST WINDS 5 TO 10 KNOTS WILL DEVELOP BY 18Z AND TURN TO THE
EAST THIS EVENING.
&&
.GLASGOW WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
WEATHER.GOV/GLASGOW
000
FXUS65 KBYZ 200925
AFDBYZ
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BILLINGS MT
325 AM MDT SUN MAY 20 2012
.SHORT TERM...VALID FOR TDY AND MON...
LIGHT SHOWER ACTIVITY FROM LAST EVENING HAS DISSIPATED AS
SHORTWAVE CONTINUES TO MOVE EAST. SKIES HAVE CLEARED IN ITS
WAKE...AND WITH LIGHT WINDS/CLEAR SKIES/LOW DEW PT DEPRESSIONS
WOULD NOT BE SURPRISED TO SEE LOCALIZED VALLEY FOG AGAIN EARLY
THIS MORNING. HAVE ADDED PATCHY FOG TO WEST AND CENTRAL PARTS FROM
09-15Z. QUIET START TO THE DAY WILL GIVE WAY TO INCREASING MID AND
HIGH CLOUD FROM THE WEST BY AFTERNOON. PRETTY GOOD MOISTURE
ADVECTION ASSOCIATED WITH THE PACIFIC FLOW...ENOUGH SUCH THAT WITH
LIFTED INDICES NEAR ZERO COULD SEE A FEW SHOWERS OVER OUR WESTERN
MOUNTAINS. CONVERGENCE ALONG WEAK SURFACE BOUNDARY...PRECEDED BY
EAST WINDS WHICH SHOULD HOLD LOW LEVEL MOISTURE IN PLACE...
SUGGESTS SOME LOWER ELEVATION SPRINKLES ARE ALSO POSSIBLE AND HAVE
ADDED THIS TO THE FORECAST AFTER 21Z. MAY ALSO SEE SOME SHOWERS
NEAR THE SOUTHEAST MT/NORTHEAST WY/SD BORDERS PER LINGERING PV IN
THIS AREA...BUT BETTER CHANCES SHOULD BE OUT OF OUR AREA AND
CLOSER TO THE BLACK HILLS. EXPECT A SOLID CLOUD COVER ACROSS MOST
OF OUR AREA DURING THE EVENING SOLAR ECLIPSE.
BUILDING UPPER LEVEL RIDGE WILL BRING WARMER CONDITIONS THE NEXT
COUPLE DAYS...WITH HIGHS IN THE 70S TODAY AND 80S TO NEAR 90 ON
MONDAY. ONSET OF HEIGHT FALLS IN OUR WEST AHEAD OF DEEPENING PAC
NW TROF WILL BRING THE THREAT OF TSTMS BY LATE AFTERNOON ON
MONDAY. WITH INTENSE SFC HEATING AND MEAGER BOUNDARY LAYER
MOISTURE THIS CONVECTION WILL BE HIGH-BASED AS IT INITIATES OFF
OUR WESTERN HIGH TERRAIN...FORECAST SOUNDINGS SUGGEST BASES NEAR
550-600MB...AND GREATEST THREAT FROM ROUGHLY 21-03Z WILL BE IN OUR
NW PARTS FROM LIVINGSTON TO HARLOWTON AND ROUNDUP. STRONG WIND
GUSTS A GOOD BET WITH THESE STORMS. WILL HIGHLIGHT THIS THREAT
ALONG WITH THE HOT TEMPS AND LOW HUMIDITY IN THE FIRE WEATHER
FORECAST.
MODELS CURRENTLY SUGGEST A PREFRONTAL TROF/WIND SHIFT WILL PUSH
THROUGH THE AREA MONDAY NIGHT...AIDED BY THE AFOREMENTIONED
CONVECTION. STRONG COLD ADVECTION ASSOCIATED WITH MAIN COLD FRONT
AND BREAK DOWN OF THE RIDGE SHOULD HOLD OFF UNTIL TUESDAY. THUS
EXPECT A MILD MONDAY NIGHT AFTER THE VERY WARM MONDAY...WITH THE
MUCH BETTER CHANCE OF PCPN ALSO HOLDING OFF UNTIL TUESDAY.
JKL
.LONG TERM...VALID FOR TUE...WED...THU...FRI...SAT...
UNSETTLED WEATHER PATTERN FOR THE EXTENDED WITH ENSEMBLE FORECASTS
INDICATING CLIMO POPS OR BETTER FOR JUST ABOUT EVERY PERIOD.
OPERATIONAL MODELS SHOWING A GREAT DEAL OF SPREAD IN STRENGTH AND
TRACK OF THE SEVERAL SYSTEMS IMPACTING THE REGION TUESDAY INTO
EARLY NEXT WEEK...SO LEANING ON THE ENSEMBLE MEAN FOR THE SREF AND
GFS FOR THIS FORECAST PACKAGE.
UPPER TROF DIGS INTO THE AREA TUESDAY WITH A WEAK NEGATIVELY
TILTED STRUCTURE. TROF SETTLES OVER THE AREA WITH CUT OFF LOW
DEVELOPING SOMEWHERE FROM NORTHERN MONTANA TO JUST INSIDE THE
CANADIAN BORDER. PLENTY OF PACIFIC MOISTURE FLOWING THROUGH THIS
SYSTEM ALONG WITH JET SUPPORTED ENERGY SO INCREASED POPS TUESDAY
INTO EARLY WEDNESDAY FOR MOST AREAS...ESPECIALLY WEST OF ROSEBUD
COUNTY. MODELS HITTING THE FOOTHILLS FROM LIVINGSTON TO SHERIDAN
HARDEST WITH THIS SYSTEM. WITH TROF AND UNSETTLED CONDITIONS
COOLED TEMPERATURES FROM THE HIGH SIDE OF GUIDANCE CLOSER TO THE
MIDDLE RANGE.
JET SAGS SOUTH OF THE AREA WEDNESDAY AND THURSDAY KEEPING
TEMPERATURES BELOW SEASONAL LEVELS. MODELS SHOWING HIGH
UNCERTAINTY WITH ANY SPECIFIC UPPER LEVEL ENERGY BUT MEAN TROF
AXIS BECOMES STRETCHED WEST TO EAST ACROSS THE FORECAST AREA
SUPPORTING CLIMO TYPE POPS...WITH HIGHER POPS FOR THE
AFTERNOON/EVENING HOURS WITH BETTER INSTABILITY.
MODELS IN AGREEMENT WITH FLOW ALOFT BECOMING STRONGLY BACKED TO
THE SOUTH ON FRIDAY AS STRONG PACIFIC STORM MOVES INTO CALIFORNIA.
WARMER TEMPERATURES WILL SPREAD NORTHWARD FRIDAY INTO SATURDAY
WITH THIS FLOW. HOWEVER THESE WARMER TEMPERATURES WILL PRODUCE
INSTABILITY THAT WILL COMBINE WITH INCREASINGLY DIVERGENT FLOW
ALOFT TO INCREASE SHOWER AND THUNDERSTORM POTENTIAL. INCREASED
POPS FOR THIS TIME FRAME TO ACCOUNT FOR THIS.
TRACK OF THE UPPER STORM OUT OF CALIFORNIA WILL BE IMPORTANT FOR
WEEKEND WEATHER AS THE OPERATIONAL GFS BRING THIS POTENT SYSTEM
INTO THE SWEET SPOT FOR A WIDESPREAD HEAVY PRECIPITATION EVENT FOR
THE FORECAST AREA...ACROSS NORTHERN WYOMING AND SLOWING INTO THE
WESTERN DAKOTAS. QPF FOR THE 00Z GFS SHOWING WIDESPREAD 2 TO 4
INCH PRECIPITATION AMOUNTS SATURDAY INTO MONDAY. GFS ENSEMBLE MEAN
AND OPERATIONAL ECMWF PUSH THE SYSTEM NORTHWARD ACROSS WESTERN
MONTANA AND INTO CANADA FOR A MUCH DRIER SOLUTION. WILL HAVE TO
WATCH THIS PERIOD CAREFULLY...AND INCREASED POPS TO CLIMATOLOGY
FOR THIS TIME FRAME. CHAMBERS
&&
.AVIATION...
PATCHY FOG WILL BE POSSIBLE WEST OF A ROUNDUP TO SHERIDAN LINE
THIS MORNING...INCLUDING THE KBIL KSHR AND KLVM TAF SITES. ANY FOG
SHOULD DISSIPATE BY 16Z. OTHERWISE VFR CONDITIONS ARE EXPECTED
TODAY. VFR CEILINGS WILL DEVELOP BY 00Z WITH ISOLATED SHOWERS
MAINLY IN THE MOUNTAINS AND FOOTHILLS INTO TONIGHT. LOCAL MVFR
CONDITIONS CAN BE EXPECTED NEAR ANY PRECIPITATION ALONG WITH
PARTIAL MOUNTAIN OBSCURATION. CHAMBERS
&&
.PRELIMINARY POINT TEMP/POPS...
TDY MON TUE WED THU FRI SAT
-------------------------------------------------------
BIL 076 052/088 059/073 043/061 040/060 042/062 045/069
0/B 10/B 15/T 43/T 23/W 33/W 33/T
LVM 074 045/085 050/063 035/055 035/057 034/058 039/067
1/B 12/T 26/T 43/T 34/W 44/W 34/T
HDN 077 048/090 056/076 043/063 040/062 042/066 045/073
0/B 10/U 14/T 43/T 23/W 33/W 32/T
MLS 076 053/089 061/079 047/065 044/063 043/065 048/071
0/U 00/U 13/T 42/T 23/W 33/W 43/T
4BQ 074 050/087 057/081 046/063 043/062 042/065 047/074
0/U 00/U 03/T 43/T 23/W 33/W 32/T
BHK 071 046/085 056/080 046/062 042/062 041/062 045/068
0/U 00/B 03/T 42/T 23/W 33/W 43/T
SHR 073 045/085 054/076 040/059 039/059 039/065 042/074
0/B 00/U 04/T 53/T 33/W 33/W 32/T
&&
.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...NONE.
WY...NONE.
&&
$$
WEATHER.GOV/BILLINGS
000
FXUS65 KTFX 200505
AFDTFX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
1100 PM MDT SAT MAY 19 2012
.UPDATE...SHORTWAVE ENERGY MOVED ACROSS THE FORECAST AREA DURING
THE AFTERNOON AND EARLY EVENING HOURS. FEATURED PRODUCED MAINLY
VARIABLE CLOUD COVER WITH ONLY A FEW SHOWERS OVER THE HIGHER
TERRAIN. RADAR AND SATELLITE IMAGERY INDICATE THIS ACTIVITY IS
COMING TO AN END WITH SKIES CLEARING FROM THE WEST OVERNIGHT. HAVE
UPDATED POP AND WEATHER TO ACCOUNT FOR CURRENT AND EXPECTED
CONDITIONS. HAVE MADE SOME MINOR TWEAKS TO WINDS...MAINLY IN THE
FAR SOUTHWEST VALLEYS THIS EVENING WHERE THEY HAVE GUSTED A BIT
HIGHER THAN EXPECTED. REMAINDER OF THE FORECAST IS IN GOOD SHAPE
WITH COOL CONDITIONS OVERNIGHT AND A WARMING TREND ON SUNDAY. MPJ
&&
.AVIATION...
UPDATED 0500Z.
EXPECT VFR CONDITIONS AND LIGHT WINDS THROUGHOUT THE TAF PERIOD. FEW
TO SCATTERED OVERNIGHT CLOUDS WILL GIVE WAY TO INCREASING AFTERNOON
CLOUDS TOMORROW. BROKEN CEILINGS AND A FEW SHOWERS WILL ONCE AGAIN
BE POSSIBLE ACROSS CENTRAL MONTANA. CONDITIONS WILL IMPROVE TOMORROW
NIGHT AHEAD OF A LARGE SYSTEM THAT WILL IMPACT THE REGION LATE MON.
&&
.PREV DISCUSSION...
/ISSUED 600 PM MDT SAT MAY 19 2012/
THIS AFTERNOON THROUGH MONDAY EVENING...AXIS OF WEAK UPPER LEVEL
TROF JUST CROSSING THE CONTINENTAL DIVIDE AS OF 2PM. SMALL AREA OF
ASSOCIATED MOISTURE AHEAD OF THE AXIS IS SPREADING SCATTERED MOSTLY
MID-LEVEL CLOUD COVER ACROSS OUR REGION. A FEW OF THE CLOUDS ARE
STARTING TO DEVELOP ENOUGH TO SHOW UP AS A LIGHT RAIN SHOWER ON
RADAR IMAGERY ALONG PORTIONS OF THE HILINE AND OVER FAR SOUTHWEST MT
AROUND DILLON/WEST YELLOWSTONE. AS THE AXIS MOVES OFF THE MTNS AND
INTO THE PLAINS THE COVERAGE OF THE SHOWERS WILL EXPAND SLIGHTLY
MAINLY OVER SOUTHWEST AND PARTS OF CENTRAL MT. ONLY LIGHT RAINFALL
AMOUNTS ARE EXPECTED FROM THIS ACTIVITY. MODELS REMAIN IN CLOSE
AGREEMENT THAT THE TROF AXIS WILL EXIT INTO ERN MT TONIGHT AND UPPER
LEVEL RIDGE CURRENTLY ALONG THE PACNW COAST WILL BUILD INTO THE NRN
ROCKIES TOMORROW...BRINGING MOSTLY FAIR SKIES AND TEMPERATURES
WARMING INTO THE UPPER 60S TO MID 70S. THE RIDGE PERSISTS UNTIL
AROUND MIDDAY MONDAY THEN SLIDES EASTWARD AS LEADING EDGE OF A DEEP
LOW PRESSURE SYSTEM IN THE ERN PACIFIC MOVES INTO WRN MT. MOISTURE
GRADUALLY BUILDS INTO THE REGION WITH SCATTERED SHOWERS AND
THUNDERSTORMS DEVELOPING ON MON AFTN/EVE MAINLY ALONG/WEST OF THE
INTERSTATE 15 CORRIDOR. WARM SOUTHWESTERLY FLOW ON THE WEST SIDE OF
THE DEPARTING RIDGE WILL PUSH TEMPS INTO THE UPPER 70S TO LOW 80S ON
MON BEFORE THE PRECIPITATION DEVELOPS.
WARANAUSKAS
MONDAY NIGHT THROUGH SATURDAY...A BROAD UPPER-LEVEL TROUGH OF LOW
PRESSURE AND ASSOCIATED SURFACE COLD FRONT WILL MOVE INTO THE
PACIFIC NORTHWEST MONDAY NIGHT. SOUTHWEST FLOW AND AMPLE PACIFIC
MOISTURE AHEAD OF THIS TROUGH WILL BRING INCREASING PRECIPITATION
CHANCES TO THE FORECAST AREA MONDAY NIGHT AND TUESDAY. THE COLD
FRONT IS EXPECTED TO MOVE THROUGH THE STATE ON TUESDAY WITH
WIDESPREAD PRECIPITATION AND COOLING TEMPERATURES EXPECTED. MODELS
ARE INDICATING THAT THIS BROAD TROUGH WILL REMAIN OVER THE WESTERN
U.S. THROUGH THE REMAINDER OF THE WEEK AND POSSIBLY INTO NEXT
WEEKEND YIELDING UNSETTLED AND COOL CONDITIONS OVER THE NORTHERN
ROCKIES. SEVERAL SHORTWAVES WILL PROPAGATE THROUGH THE
TROUGH...HOWEVER CONFIDENCE IS LOW REGARDING THE TIMING OF EACH OF
THESE WAVES AS WELL AS PRECIPITATION AMOUNTS. ON THURSDAY...THE GFS
BRINGS A CLOSED AREA OF LOW PRESSURE OVER MONTANA WHILE THE ECMWF
KEEPS A CLOSED LOW ALONG THE WEST COAST. BOTH SOLUTIONS SUGGEST
PRECIPITATION OVER THE FORECAST AREA...HOWEVER EACH SOLUTION DIFFERS
ON WHICH AREAS CAN EXPECT THE MOST PRECIPITATION. SO FOR NOW HAVE
KEPT CHANCE POPS IN THE PLAINS WITH LIKELY POPS IN THE MOUNTAINS FOR
THE MIDDLE PART OF NEXT WEEK AND THEN CHANCE POPS OVER THE ENTIRE
AREA FOR THE LATTER HALF OF THE FORECAST PERIOD GIVEN THE
UNCERTAINTY. IN ADDITION...TEMPERATURES COULD BE AROUND 10 DEGREES
BELOW SEASONAL AVERAGES WITH SNOW LEVELS LOWERING TO NEAR 6000 FEET
BY THURSDAY. OVERALL...EACH MODEL SOLUTION INDICATES THAT A WETTER
AND COOLER PATTERN IS EXPECTED FOR MOST OF NEXT WEEK AND POTENTIALLY
INTO THE MEMORIAL DAY HOLIDAY WEEKEND. MLV
&&
.PRELIMINARY POINT TEMPS/POPS...
GTF 40 74 51 80 / 10 0 0 20
CTB 37 72 48 74 / 10 0 10 20
HLN 40 74 49 81 / 10 0 0 20
BZN 37 73 44 82 / 10 0 0 10
WEY 30 64 35 72 / 10 0 10 10
DLN 38 72 44 79 / 10 0 0 20
HVR 41 74 50 79 / 10 0 10 10
LWT 38 70 47 78 / 10 0 0 10
&&
.TFX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
WEATHER.GOV/GREATFALLS
000
FXUS65 KGGW 200318 AAB
AFDGGW
AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE GLASGOW MT
918 PM MDT SAT MAY 19 2012
.SHORT TERM...FOR NORTHEAST MONTANA...TONIGHT THROUGH MONDAY...
SHALLOW UPPER TROUGH AND WEAK BOUNDARY ALONG THE INTERNATIONAL
BORDER HAS SPREAD LOW BROKEN CLOUDS ACROSS THE AREA WITH
ISOLATED SHOWERS. WENT AHEAD AND SPREAD ISOLATED SHOWERS WITH LOW
QPF FARTHER EAST ACROSS NEMONT TONIGHT BASED ON RAP GUIDANCE AND
RADAR. MADE ADDITIONAL MINOR TWEAKS TO TEMPERATURES AND WINDS. SCT
EARLY UPDATE BASED ON RADAR ECHOES...
A WEAK SHORTWAVE MOVING ACROSS NORTHEAST MONTANA THIS EVENING IS
PRODUCING LOW LEVEL CLOUDS AND RADAR ECHOES IN NORTHERN PHILLIPS
COUNTY AND NORTHERN VALLEY COUNTY. THE ONLY MODEL THAT IS PICKING
UP ON THIS NOW IS THE RAPID REFRESH MODEL (RAP). WITH A SURFACE
HIGH IN PLACE OVER NEMONT MOST OF THE ECHOES ARE LIKELY NOT
REACHING THE GROUND WITH ENOUGH RAIN TO AMOUNT TO MUCH. BUT WENT
AHEAD A BUMPED POPS A BIT TO ISOLATED FOR THE POSSIBILITY OF A FEW
AREAS OF SHOWERS REACHING THE GROUND...SINCE TEMPERATURES ARE ONLY
IN THE 50S ALONG THE INTERNATIONAL BORDER. THE RAP INDICATES THAT
THE SHOWERS WILL DIMINISH AS THEY MOVE EAST THIS EVENING. SO
CONFINED SHOWERS TO THE NW. SCT
PREVIOUS DISCUSSION...
WATER VAPOR IMAGERY AND 500 MB HEIGHT FIELD SHOWS A SIMILAR AND
SLIGHTLY LESS ACTIVE PATTERN THAN YESTERDAY. A LOW PRESSURE
CIRCULATION OFF THE SOUTH CAROLINA COAST HAS BECOME THE FIRST
TROPICAL OF THE ATLANTIC HURRICANE SEASON WHILE INTRODUCING SOME
SCATTERED THUNDERSTORMS INTO THE INTERIOR SOUTHEAST. HIGH PRESSURE
CONTINUES TO HOLD SWAY OVER THE LOWER MISSISSIPPI AND OHIO RIVER
VALLEYS. THE SLOW- MOVING UPPER TROUGH WHICH HAS FINALLY EMERGED
ONTO THE CENTRAL HIGH PLAINS CONTINUES TO SPAWN THUNDERSTORMS
THERE. THUNDERSTORMS ARE ALSO SETTING OFF OVER SOUTHERN FLORIDA.
REGIONALLY FOR US...AS THE NORTHERN ROCKIES AND NORTHERN HIGH
PLAINS COMES AWAY FROM THE LARGER UPPER LEVEL TROUGH...ZONAL FLOW
IS OSCILLATING WITH A WEAK TROUGH TO STILL ALLOW PARTLY CLOUDY
SKIES AND A FEW SPRINKLES...ESPECIALLY OVER NORTH CENTRAL MONTANA.
LOCALLY...SURFACE HIGH PRESSURE IS KEEPING SKIES MOSTLY SUNNY OVER
OUR CENTRAL AND EASTERN ZONES...WHILE A WEAK INVERTED SURFACE
TROUGH IS PROVIDING ENOUGH LIFT TO SPREAD SOME MID TO UPPER LEVEL
CLOUDS OVER CENTRAL MONTANA AND INTO OUR FAR WESTERN ZONES THIS
AFTERNOON. TODAY...WITH THE RELATIVELY DRY AIR IN PLACE...I DO NOT
EXPECT THIS INCREASE IN CLOUDINESS TO BRING MUCH MORE THAN SOME
ISOLATED LIGHT VIRGA RAIN SHOWERS OR SPRINKLES TO OUR WESTERN AND
NORTHWESTERN ZONES TODAY AND TONIGHT.
SUNDAY AND MONDAY...WEAK UPPER LEVEL RIDGING TAKES OVER ACROSS
MONTANA AS TEMPERATURES CLIMB INTO THE 70S AND 80S RESPECTFULLY.
THERE MAY BE JUST ENOUGH MID LEVEL MOISTURE TO SET OF SOME AREA
VIRGA SHOWERS OR SPRINKLES AROUND THE PERIMETER EDGES OF OUR
CWA...SIMILAR TO TODAY.
A LARGE AND STRONG UPPER LEVEL TROUGH THEN SPREADS INTO THE
PACIFIC NORTHWEST TOWARD THE END OF THIS SHORT TERM FORECAST
PERIOD...BRINGING A SOUTHWEST FLOW ALOFT AND INCREASED CLOUDINESS
TO OUR REGION. BMICKELSON
.LONG TERM...MONDAY NIGHT THROUGH SATURDAY...
LONG WAVE TROF DIGGING ACROSS THE WESTERN STATES DOMINATES THE
EXTENDED PERIOD. MODELS DIFFERING MAINLY ON WHERE THE MOISTURE
AND ENERGY WILL AT VARIOUS TIMES IN THE EVOLUTION OF THE SYSTEM.
OVERALL MAIN ADJUSTMENT WAS TO BACK OFF SLIGHTLY ON THE POPS WITH
THE SUGGESTED SPLITTING OF THE SYSTEM AND FOCUS OF THE MAIN LOW
OVER THE GREAT BASIN. EBERT
PREVIOUS LONG TERM DISCUSSION...UPPER RIDGE MOVES TO THE EAST
MONDAY NIGHT AND SOUTHWEST FLOW ALOFT WILL PREVAIL AHEAD OF AN
UPPER LOW THAT MOVES INTO THE AREA BY WEDNESDAY. THERE WILL BE A
COLD FRONT MOVING THROUGH EASTERN MONTANA DURING THE DAY ON
TUESDAY. AIRMASS ALONG AND AHEAD OF THE FRONT SHOULD BE UNSTABLE
ENOUGH TO SUPPORT SOME THUNDERSTORMS. MODELS HAVE VARIED ON WHERE
THE BEST INSTABILITY WILL BE. WILL MENTION A CHANCE OF
THUNDERSTORMS.
THE GFS AND ECMWF PLACE THE UPPER LOW DIFFERENTLY ON WEDNESDAY AND
WEDNESDAY NIGHT WITH GFS FAVORING MONTANA AND ECMWF PUTTING THE
LOW IN SASKATCHEWAN. BOTH MODELS HAVE EASTERN MONTANA IN A DRY
SLOT FOR AT LEAST PART OF THE DAY. HOWEVER...THAT WILL ALLOW FOR
DAYTIME HEATING TO DESTABILIZE THE ATMOSPHERE. MAY SEE SOME
SHOWERS AND THUNDERSTORMS DEVELOP AS A RESULT. WILL MENTION A
CHANCE FOR NOW.
THE MODEL DIFFERENCES CONTINUE THURSDAY WITH THE ECMWF KEEPING THE
UPPER LOW IN SASKATCHEWAN AND DRY SLOT OVER EASTERN MONTANA WHILE
THE GFS TRACKS ITS UPPER LOW INTO NORTH DAKOTA AND MANITOBA. WILL
MAINTAIN A CHANCE OF SHOWERS GIVEN THE UNCERTAINTY.
FRIDAY AND SATURDAY...THE NEXT UPPER LOW DIGS SOUTH INTO NORTHERN
CALIFORNIA WITH RIDGE TO THE EAST. MONTANA WILL BE IN A SOMEWHAT
MOIST SOUTHWEST FLOW ALOFT. WILL MAINTAIN A CHANCE OF SHOWERS FOR
NOW. FORRESTER
&&
.AVIATION...
VFR. A FEW EVENING SHOWERS WILL MOVE THROUGH THE REGION. THEN
AFTER 06Z LOOK FOR CLEARING SKIES AND LIGHT WIND WHICH WILL
DOMINATE THROUGH SUNDAY. PROTON
&&
.GLASGOW WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
WEATHER.GOV/GLASGOW
000
FXUS65 KTFX 200313
AFDTFX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
913 PM MDT SAT MAY 19 2012
.UPDATE...SHORTWAVE ENERGY MOVED ACROSS THE FORECAST AREA DURING
THE AFTERNOON AND EARLY EVENING HOURS. FEATURED PRODUCED MAINLY
VARIABLE CLOUD COVER WITH ONLY A FEW SHOWERS OVER THE HIGHER
TERRAIN. RADAR AND SATELLITE IMAGERY INDICATE THIS ACTIVITY IS
COMING TO AN END WITH SKIES CLEARING FROM THE WEST OVERNIGHT. HAVE
UPDATED POP AND WEATHER TO ACCOUNT FOR CURRENT AND EXPECTED
CONDITIONS. HAVE MADE SOME MINOR TWEAKS TO WINDS...MAINLY IN THE
FAR SOUTHWEST VALLEYS THIS EVENING WHERE THEY HAVE GUSTED A BIT
HIGHER THAN EXPECTED. REMAINDER OF THE FORECAST IS IN GOOD SHAPE
WITH COOL CONDITIONS OVERNIGHT AND A WARMING TREND ON SUNDAY. MPJ
&&
.AVIATION...
UPDATED 0000Z.
EXPECT VFR CONDITIONS AND LIGHT WINDS THROUGHOUT THE TAF PERIOD.
SCATTERED TO BROKEN CEILINGS AND A FEW SHOWERS ARE POSSIBLE THIS
EVENING AS WELL. CONDITIONS WILL IMPROVE SOME OVERNIGHT BEFORE
CEILINGS AND ISOLATED SHOWERS MOVE BACK INTO THE REGION TOMORROW.
&&
.PREV DISCUSSION...
/ISSUED 600 PM MDT SAT MAY 19 2012/
THIS AFTERNOON THROUGH MONDAY EVENING...AXIS OF WEAK UPPER LEVEL
TROF JUST CROSSING THE CONTINENTAL DIVIDE AS OF 2PM. SMALL AREA OF
ASSOCIATED MOISTURE AHEAD OF THE AXIS IS SPREADING SCATTERED MOSTLY
MID-LEVEL CLOUD COVER ACROSS OUR REGION. A FEW OF THE CLOUDS ARE
STARTING TO DEVELOP ENOUGH TO SHOW UP AS A LIGHT RAIN SHOWER ON
RADAR IMAGERY ALONG PORTIONS OF THE HILINE AND OVER FAR SOUTHWEST MT
AROUND DILLON/WEST YELLOWSTONE. AS THE AXIS MOVES OFF THE MTNS AND
INTO THE PLAINS THE COVERAGE OF THE SHOWERS WILL EXPAND SLIGHTLY
MAINLY OVER SOUTHWEST AND PARTS OF CENTRAL MT. ONLY LIGHT RAINFALL
AMOUNTS ARE EXPECTED FROM THIS ACTIVITY. MODELS REMAIN IN CLOSE
AGREEMENT THAT THE TROF AXIS WILL EXIT INTO ERN MT TONIGHT AND UPPER
LEVEL RIDGE CURRENTLY ALONG THE PACNW COAST WILL BUILD INTO THE NRN
ROCKIES TOMORROW...BRINGING MOSTLY FAIR SKIES AND TEMPERATURES
WARMING INTO THE UPPER 60S TO MID 70S. THE RIDGE PERSISTS UNTIL
AROUND MIDDAY MONDAY THEN SLIDES EASTWARD AS LEADING EDGE OF A DEEP
LOW PRESSURE SYSTEM IN THE ERN PACIFIC MOVES INTO WRN MT. MOISTURE
GRADUALLY BUILDS INTO THE REGION WITH SCATTERED SHOWERS AND
THUNDERSTORMS DEVELOPING ON MON AFTN/EVE MAINLY ALONG/WEST OF THE
INTERSTATE 15 CORRIDOR. WARM SOUTHWESTERLY FLOW ON THE WEST SIDE OF
THE DEPARTING RIDGE WILL PUSH TEMPS INTO THE UPPER 70S TO LOW 80S ON
MON BEFORE THE PRECIPITATION DEVELOPS.
WARANAUSKAS
MONDAY NIGHT THROUGH SATURDAY...A BROAD UPPER-LEVEL TROUGH OF LOW
PRESSURE AND ASSOCIATED SURFACE COLD FRONT WILL MOVE INTO THE
PACIFIC NORTHWEST MONDAY NIGHT. SOUTHWEST FLOW AND AMPLE PACIFIC
MOISTURE AHEAD OF THIS TROUGH WILL BRING INCREASING PRECIPITATION
CHANCES TO THE FORECAST AREA MONDAY NIGHT AND TUESDAY. THE COLD
FRONT IS EXPECTED TO MOVE THROUGH THE STATE ON TUESDAY WITH
WIDESPREAD PRECIPITATION AND COOLING TEMPERATURES EXPECTED. MODELS
ARE INDICATING THAT THIS BROAD TROUGH WILL REMAIN OVER THE WESTERN
U.S. THROUGH THE REMAINDER OF THE WEEK AND POSSIBLY INTO NEXT
WEEKEND YIELDING UNSETTLED AND COOL CONDITIONS OVER THE NORTHERN
ROCKIES. SEVERAL SHORTWAVES WILL PROPAGATE THROUGH THE
TROUGH...HOWEVER CONFIDENCE IS LOW REGARDING THE TIMING OF EACH OF
THESE WAVES AS WELL AS PRECIPITATION AMOUNTS. ON THURSDAY...THE GFS
BRINGS A CLOSED AREA OF LOW PRESSURE OVER MONTANA WHILE THE ECMWF
KEEPS A CLOSED LOW ALONG THE WEST COAST. BOTH SOLUTIONS SUGGEST
PRECIPITATION OVER THE FORECAST AREA...HOWEVER EACH SOLUTION DIFFERS
ON WHICH AREAS CAN EXPECT THE MOST PRECIPITATION. SO FOR NOW HAVE
KEPT CHANCE POPS IN THE PLAINS WITH LIKELY POPS IN THE MOUNTAINS FOR
THE MIDDLE PART OF NEXT WEEK AND THEN CHANCE POPS OVER THE ENTIRE
AREA FOR THE LATTER HALF OF THE FORECAST PERIOD GIVEN THE
UNCERTAINTY. IN ADDITION...TEMPERATURES COULD BE AROUND 10 DEGREES
BELOW SEASONAL AVERAGES WITH SNOW LEVELS LOWERING TO NEAR 6000 FEET
BY THURSDAY. OVERALL...EACH MODEL SOLUTION INDICATES THAT A WETTER
AND COOLER PATTERN IS EXPECTED FOR MOST OF NEXT WEEK AND POTENTIALLY
INTO THE MEMORIAL DAY HOLIDAY WEEKEND. MLV
&&
.PRELIMINARY POINT TEMPS/POPS...
GTF 40 74 51 80 / 10 0 0 20
CTB 37 72 48 74 / 10 0 10 20
HLN 40 74 49 81 / 10 0 0 20
BZN 37 73 44 82 / 10 0 0 10
WEY 30 64 35 72 / 10 0 10 10
DLN 38 72 44 79 / 10 0 0 20
HVR 41 74 50 79 / 10 0 10 10
LWT 38 70 47 78 / 10 0 0 10
&&
.TFX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
WEATHER.GOV/GREATFALLS
000
FXUS65 KBYZ 200301
AFDBYZ
AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE BILLINGS MT
901 PM MDT SAT MAY 19 2012
.SHORT TERM...VALID FOR SUN AND MON...
WEAK SHORTWAVE IN A ZONAL FLOW HAS TRIGGERED SOME WEAK SHOWERS
ACROSS WESTERN AND CENTRAL ZONES THIS EVENING. CONVECTION PRETTY
LIMITED AS EVIDENCED BY NO LIGHTNING STRIKES ACROSS OUR FORECAST
AREA...BUT ENOUGH THERE TO CARRY THE POPS PAST BILLINGS EVEN WITH
THE SETTING SUN. PUSHED LOW POPS FARTHER EAST FOR THE REMAINDER
OF THE EVENING AND REMOVED MENTION OF THUNDER. PUSHED CLOUD COVER
EAST TO TRACK THE SHORTWAVE. TEMPERATURES LOOKED IN GOOD SHAPE.
NO OTHER CHANGES. TWH
.LONG TERM...VALID FOR TUE...WED...THU...FRI...SAT...
MODEL AGREEMENT CONTINUES TO BE GOOD IN THE OVERALL EVOLUTION OF
THE SYNOPTIC PATTERN FOR THE EXTENDED FORECAST. TUESDAY IS STILL
ON TRACK TO BE THE TRANSITION DAY TO A COOLER AND MORE UNSETTLED
PATTERN. THIS PATTERN WILL PERSIST THROUGH THE END OF THE WEEK
BEFORE THE MODELS SUGGEST A TRANSITION TO SOUTHWESTERLY FLOW BY
FRIDAY AND SATURDAY.
THE INITIAL PACIFIC TROUGH IS STILL ON TARGET TO PUSH A COLD FRONT
ACROSS THE AREA DURING THE DAY ON TUESDAY. THIS WILL USER IN
COOLER TEMPERATURES FROM WEST TO EAST...ECLIPSING THE HIGH
TEMPERATURES IN WESTERN ZONES...BUT LEAVING EASTERN ZONES TO GET
QUITE WARM AHEAD OF THE FRONT. SHOWERS AND THUNDERSTORMS ARE
EXPECTED TO DEVELOP BEHIND THE COLD FRONT AS THE BETTER MOISTURE
AND QG FORCING REACH THE AREA. HAVE INCREASED POPS ON TUESDAY A
BIT TO SHOWCASE THE POTENTIAL PRECIPITATION THREAT AS THE COLD
FRONT MOVES TROUGH.
SCATTERED SHOWERS AND POSSIBLY A FEW THUNDERSTORMS WILL CONTINUE
INTO WEDNESDAY AS DISORGANIZED VORTICITY MAXIMA ROTATE THROUGH THE
MEAN TROUGH AND ACROSS OUR CWA. TEMPERATURES WILL BE MUCH COOLER
AND BELOW AVERAGE ON WEDNESDAY AS THE TROUGH AS 850 TEMPERATURES
WILL BE AROUND +10C ACROSS THE AREA. THE TROUGH CONTINUES TO
LINGER OVER THE AREA ON THURSDAY BEFORE STARTING PULL OUT TOWARD
THE EAST. THE GFS SOLUTION ADVECTS 850 MB TEMPERATURES OF +2 TO
+8 C OVER THE AREA BY THURSDAY AFTERNOON. THE 12Z RUN OF THE ECMWF
IS NOT AS COOL ON THURSDAY AS IT QUICKLY EJECTS THE INITIAL TROUGH
TOWARD THE EAST AND STARTS BUILDING IN THE SOUTHWESTERLY FLOW MORE
QUICKLY. THUS HAVE NOT TOUCHED TEMPERATURES MUCH ON THURSDAY...BUT
DID COOL TEMPERATURES A COUPLE DEGREES ON WEDNESDAY.
THE MODEL AGREEMENT CONTINUES TO BE GOOD FOR DEVELOPING A CUTOFF
LOW OVER THE WESTERN CONUS BY FRIDAY. THIS DEVELOPS SOUTHWESTERLY
FLOW ACROSS OUR AREA ON FRIDAY AND SATURDAY. THE ECMWF IS FASTER
AT DEVELOPING THIS SOLUTION...AND KICKS A WARM FRONT ACROSS THE
AREA ON FRIDAY WHILE THE GFS IS A BIT SLOWER IN THE EVOLUTION AND
KICKS THE WARM FRONT ACROSS THE AREA ON SATURDAY. GIVEN THE
INCREASING CONFIDENCE IN THIS OVERALL SOLUTION HAVE STARTED
INCREASING TEMPERATURES FOR SATURDAY...BUT WILL HAVE TO KEEP AN
EYE ON FRIDAY IF MODELS TREND TOWARD THE FASTER ECMWF SOLUTION.
THIS PATTERN WOULD ALLOW US TO TAP INTO SOME GOLF OF MEXICO
MOISTURE AND COULD SET UP A WET MEMORIAL DAY WEEKEND FOR THE AREA.
THE INCREASED POPS BY THE MID-SHIFT FOR FRIDAY AND SATURDAY
CONTINUE TO LOOK GOOD FOR NOW...BUT WILL HAVE TO BE INCREASED IF
MODEL CONFIDENCE CONTINUES TO INCREASE. CHURCH
&&
.AVIATION...
ISOLATED SHOWERS WILL BE POSSIBLE THROUGH TONIGHT. CONDITIONS
SHOULD REMAIN VFR. DRY AND VFR CONDITIONS WILL PREVAIL OVERNIGHT
THROUGH SUNDAY. ISOLATED SHOWERS/THUNDERSTORMS WILL DEVELOP OVER
THE MOUNTAINS SUNDAY AFTERNOON/EVENING. BRS
&&
.PRELIMINARY POINT TEMP/POPS...
SUN MON TUE WED THU FRI SAT
-----------------------------------------------------------
BIL 045/076 052/088 060/076 047/060 044/058 044/061 043/071
20/B 00/U 14/T 44/T 34/W 33/W 33/T
LVM 035/074 045/085 050/066 039/056 037/053 038/056 036/067
20/B 00/U 25/T 54/T 34/W 44/W 34/T
HDN 042/077 049/089 057/079 044/061 043/060 040/062 045/072
20/B 00/B 13/T 43/T 34/W 33/W 33/T
MLS 042/076 053/089 063/083 048/065 046/062 042/064 046/071
20/U 00/B 12/T 43/T 24/W 33/W 33/T
4BQ 042/074 050/087 059/084 045/063 043/061 041/063 047/074
10/B 00/U 02/T 43/T 24/W 33/W 43/T
BHK 037/071 046/085 055/084 050/063 044/061 041/061 047/070
00/U 00/B 12/T 43/T 24/W 33/W 43/T
SHR 038/073 045/085 054/079 041/059 039/057 037/060 043/072
20/B 00/U 03/T 53/T 34/W 33/W 43/T
&&
.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...NONE.
WY...NONE.
&&
$$
WEATHER.GOV/BILLINGS
000
FXUS65 KGGW 200107 AAA
AFDGGW
AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE GLASGOW MT
707 PM MDT SAT MAY 19 2012
.SHORT TERM...FOR NORTHEAST MONTANA...TONIGHT THROUGH MONDAY...
EARLY UPDATE BASED ON RADAR ECHOES...A WEAK SHORTWAVE MOVING
ACROSS NORTHEAST MONTANA THIS EVENING IS PRODUCING LOW LEVEL
CLOUDS AND RADAR ECHOES IN NORTHERN PHILLIPS COUNTY AND NORTHERN
VALLEY COUNTY. THE ONLY MODEL THAT IS PICKING UP ON THIS NOW IS
THE RAPID REFRESH MODEL (RAP). WITH A SURFACE HIGH IN PLACE OVER
NEMONT MOST OF THE ECHOES ARE LIKELY NOT REACHING THE GROUND WITH
ENOUGH RAIN TO AMOUNT TO MUCH. BUT WENT AHEAD A BUMPED POPS A BIT
TO ISOLATED FOR THE POSSIBILITY OF A FEW AREAS OF SHOWERS REACHING
THE GROUND...SINCE TEMPERATURES ARE ONLY IN THE 50S ALONG THE
INTERNATIONAL BORDER. THE RAP INDICATES THAT THE SHOWERS WILL
DIMINISH AS THEY MOVE EAST THIS EVENING. SO CONFINED SHOWERS TO
THE NW. SCT
PREVIOUS DISCUSSION...
WATER VAPOR IMAGERY AND 500 MB HEIGHT FIELD SHOWS A SIMILAR AND
SLIGHTLY LESS ACTIVE PATTERN THAN YESTERDAY. A LOW PRESSURE
CIRCULATION OFF THE SOUTH CAROLINA COAST HAS BECOME THE FIRST
TROPICAL OF THE ATLANTIC HURRICANE SEASON WHILE INTRODUCING SOME
SCATTERED THUNDERSTORMS INTO THE INTERIOR SOUTHEAST. HIGH PRESSURE
CONTINUES TO HOLD SWAY OVER THE LOWER MISSISSIPPI AND OHIO RIVER
VALLEYS. THE SLOW-MOVING UPPER TROUGH WHICH HAS FINALLY EMERGED
ONTO THE CENTRAL HIGH PLAINS CONTINUES TO SPAWN THUNDERSTORMS
THERE. THUNDERSTORMS ARE ALSO SETTING OFF OVER SOUTHERN FLORIDA.
REGIONALLY FOR US...AS THE NORTHERN ROCKIES AND NORTHERN HIGH
PLAINS COMES AWAY FROM THE LARGER UPPER LEVEL TROUGH...ZONAL FLOW
IS OSCILLATING WITH A WEAK TROUGH TO STILL ALLOW PARTLY CLOUDY
SKIES AND A FEW SPRINKLES...ESPECIALLY OVER NORTH CENTRAL MONTANA.
LOCALLY...SURFACE HIGH PRESSURE IS KEEPING SKIES MOSTLY SUNNY OVER
OUR CENTRAL AND EASTERN ZONES...WHILE A WEAK INVERTED SURFACE
TROUGH IS PROVIDING ENOUGH LIFT TO SPREAD SOME MID TO UPPER LEVEL
CLOUDS OVER CENTRAL MONTANA AND INTO OUR FAR WESTERN ZONES THIS
AFTERNOON. TODAY...WITH THE RELATIVELY DRY AIR IN PLACE...I DO NOT
EXPECT THIS INCREASE IN CLOUDINESS TO BRING MUCH MORE THAN SOME
ISOLATED LIGHT VIRGA RAIN SHOWERS OR SPRINKLES TO OUR WESTERN AND
NORTHWESTERN ZONES TODAY AND TONIGHT.
SUNDAY AND MONDAY...WEAK UPPER LEVEL RIDGING TAKES OVER ACROSS
MONTANA AS TEMPERATURES CLIMB INTO THE 70S AND 80S RESPECTFULLY.
THERE MAY BE JUST ENOUGH MID LEVEL MOISTURE TO SET OF SOME AREA
VIRGA SHOWERS OR SPRINKLES AROUND THE PERIMETER EDGES OF OUR
CWA...SIMILAR TO TODAY.
A LARGE AND STRONG UPPER LEVEL TROUGH THEN SPREADS INTO THE
PACIFIC NORTHWEST TOWARD THE END OF THIS SHORT TERM FORECAST
PERIOD...BRINGING A SOUTHWEST FLOW ALOFT AND INCREASED CLOUDINESS TO
OUR REGION. BMICKELSON
.LONG TERM...MONDAY NIGHT THROUGH SATURDAY...
LONG WAVE TROF DIGGING ACROSS THE WESTERN STATES DOMINATES THE
EXTENDED PERIOD. MODELS DIFFERING MAINLY ON WHERE THE MOISTURE
AND ENERGY WILL AT VARIOUS TIMES IN THE EVOLUTION OF THE SYSTEM.
OVERALL MAIN ADJUSTMENT WAS TO BACK OFF SLIGHTLY ON THE POPS WITH
THE SUGGESTED SPLITTING OF THE SYSTEM AND FOCUS OF THE MAIN LOW
OVER THE GREAT BASIN. EBERT
PREVIOUS LONG TERM DISCUSSION...UPPER RIDGE MOVES TO THE EAST
MONDAY NIGHT AND SOUTHWEST FLOW ALOFT WILL PREVAIL AHEAD OF AN
UPPER LOW THAT MOVES INTO THE AREA BY WEDNESDAY. THERE WILL BE A
COLD FRONT MOVING THROUGH EASTERN MONTANA DURING THE DAY ON
TUESDAY. AIRMASS ALONG AND AHEAD OF THE FRONT SHOULD BE UNSTABLE
ENOUGH TO SUPPORT SOME THUNDERSTORMS. MODELS HAVE VARIED ON WHERE
THE BEST INSTABILITY WILL BE. WILL MENTION A CHANCE OF
THUNDERSTORMS.
THE GFS AND ECMWF PLACE THE UPPER LOW DIFFERENTLY ON WEDNESDAY AND
WEDNESDAY NIGHT WITH GFS FAVORING MONTANA AND ECMWF PUTTING THE
LOW IN SASKATCHEWAN. BOTH MODELS HAVE EASTERN MONTANA IN A DRY
SLOT FOR AT LEAST PART OF THE DAY. HOWEVER...THAT WILL ALLOW FOR
DAYTIME HEATING TO DESTABILIZE THE ATMOSPHERE. MAY SEE SOME
SHOWERS AND THUNDERSTORMS DEVELOP AS A RESULT. WILL MENTION A
CHANCE FOR NOW.
THE MODEL DIFFERENCES CONTINUE THURSDAY WITH THE ECMWF KEEPING THE
UPPER LOW IN SASKATCHEWAN AND DRY SLOT OVER EASTERN MONTANA WHILE
THE GFS TRACKS ITS UPPER LOW INTO NORTH DAKOTA AND MANITOBA. WILL
MAINTAIN A CHANCE OF SHOWERS GIVEN THE UNCERTAINTY.
FRIDAY AND SATURDAY...THE NEXT UPPER LOW DIGS SOUTH INTO NORTHERN
CALIFORNIA WITH RIDGE TO THE EAST. MONTANA WILL BE IN A SOMEWHAT
MOIST SOUTHWEST FLOW ALOFT. WILL MAINTAIN A CHANCE OF SHOWERS FOR
NOW. FORRESTER
&&
.AVIATION...
VFR. A FEW EVENING SHOWERS WILL MOVE THROUGH THE REGION. THEN
AFTER 06Z LOOK FOR CLEARING SKIES AND LIGHT WIND WHICH WILL
DOMINATE THROUGH SUNDAY. PROTON
&&
.GLASGOW WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
WEATHER.GOV/GLASGOW
000
FXUS65 KTFX 200000
AFDTFX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
600 PM MDT SAT MAY 19 2012
.DISCUSSION...
THIS AFTERNOON THROUGH MONDAY EVENING...AXIS OF WEAK UPPER LEVEL
TROF JUST CROSSING THE CONTINENTAL DIVIDE AS OF 2PM. SMALL AREA OF
ASSOCIATED MOISTURE AHEAD OF THE AXIS IS SPREADING SCATTERED MOSTLY
MID-LEVEL CLOUD COVER ACROSS OUR REGION. A FEW OF THE CLOUDS ARE
STARTING TO DEVELOP ENOUGH TO SHOW UP AS A LIGHT RAIN SHOWER ON
RADAR IMAGERY ALONG PORTIONS OF THE HILINE AND OVER FAR SOUTHWEST MT
AROUND DILLON/WEST YELLOWSTONE. AS THE AXIS MOVES OFF THE MTNS AND
INTO THE PLAINS THE COVERAGE OF THE SHOWERS WILL EXPAND SLIGHTLY
MAINLY OVER SOUTHWEST AND PARTS OF CENTRAL MT. ONLY LIGHT RAINFALL
AMOUNTS ARE EXPECTED FROM THIS ACTIVITY. MODELS REMAIN IN CLOSE
AGREEMENT THAT THE TROF AXIS WILL EXIT INTO ERN MT TONIGHT AND UPPER
LEVEL RIDGE CURRENTLY ALONG THE PACNW COAST WILL BUILD INTO THE NRN
ROCKIES TOMORROW...BRINGING MOSTLY FAIR SKIES AND TEMPERATURES
WARMING INTO THE UPPER 60S TO MID 70S. THE RIDGE PERSISTS UNTIL
AROUND MIDDAY MONDAY THEN SLIDES EASTWARD AS LEADING EDGE OF A DEEP
LOW PRESSURE SYSTEM IN THE ERN PACIFIC MOVES INTO WRN MT. MOISTURE
GRADUALLY BUILDS INTO THE REGION WITH SCATTERED SHOWERS AND
THUNDERSTORMS DEVELOPING ON MON AFTN/EVE MAINLY ALONG/WEST OF THE
INTERSTATE 15 CORRIDOR. WARM SOUTHWESTERLY FLOW ON THE WEST SIDE OF
THE DEPARTING RIDGE WILL PUSH TEMPS INTO THE UPPER 70S TO LOW 80S ON
MON BEFORE THE PRECIPITATION DEVELOPS.
WARANAUSKAS
MONDAY NIGHT THROUGH SATURDAY...A BROAD UPPER-LEVEL TROUGH OF LOW
PRESSURE AND ASSOCIATED SURFACE COLD FRONT WILL MOVE INTO THE
PACIFIC NORTHWEST MONDAY NIGHT. SOUTHWEST FLOW AND AMPLE PACIFIC
MOISTURE AHEAD OF THIS TROUGH WILL BRING INCREASING PRECIPITATION
CHANCES TO THE FORECAST AREA MONDAY NIGHT AND TUESDAY. THE COLD
FRONT IS EXPECTED TO MOVE THROUGH THE STATE ON TUESDAY WITH
WIDESPREAD PRECIPITATION AND COOLING TEMPERATURES EXPECTED. MODELS
ARE INDICATING THAT THIS BROAD TROUGH WILL REMAIN OVER THE WESTERN
U.S. THROUGH THE REMAINDER OF THE WEEK AND POSSIBLY INTO NEXT
WEEKEND YIELDING UNSETTLED AND COOL CONDITIONS OVER THE NORTHERN
ROCKIES. SEVERAL SHORTWAVES WILL PROPAGATE THROUGH THE
TROUGH...HOWEVER CONFIDENCE IS LOW REGARDING THE TIMING OF EACH OF
THESE WAVES AS WELL AS PRECIPITATION AMOUNTS. ON THURSDAY...THE GFS
BRINGS A CLOSED AREA OF LOW PRESSURE OVER MONTANA WHILE THE ECMWF
KEEPS A CLOSED LOW ALONG THE WEST COAST. BOTH SOLUTIONS SUGGEST
PRECIPITATION OVER THE FORECAST AREA...HOWEVER EACH SOLUTION DIFFERS
ON WHICH AREAS CAN EXPECT THE MOST PRECIPITATION. SO FOR NOW HAVE
KEPT CHANCE POPS IN THE PLAINS WITH LIKELY POPS IN THE MOUNTAINS FOR
THE MIDDLE PART OF NEXT WEEK AND THEN CHANCE POPS OVER THE ENTIRE
AREA FOR THE LATTER HALF OF THE FORECAST PERIOD GIVEN THE
UNCERTAINTY. IN ADDITION...TEMPERATURES COULD BE AROUND 10 DEGREES
BELOW SEASONAL AVERAGES WITH SNOW LEVELS LOWERING TO NEAR 6000 FEET
BY THURSDAY. OVERALL...EACH MODEL SOLUTION INDICATES THAT A WETTER
AND COOLER PATTERN IS EXPECTED FOR MOST OF NEXT WEEK AND POTENTIALLY
INTO THE MEMORIAL DAY HOLIDAY WEEKEND. MLV
&&
.AVIATION...
UPDATED 0000Z.
EXPECT VFR CONDITIONS AND LIGHT WINDS THROUGHOUT THE TAF PERIOD.
SCATTERED TO BROKEN CEILINGS AND A FEW SHOWERS ARE POSSIBLE THIS
EVENING AS WELL. CONDITIONS WILL IMPROVE SOME OVERNIGHT BEFORE
CEILINGS AND ISOLATED SHOWERS MOVE BACK INTO THE REGION TOMORROW.
&&
.PRELIMINARY POINT TEMPS/POPS...
GTF 40 74 50 80 / 10 10 0 20
CTB 35 72 46 74 / 10 10 20 20
HLN 39 75 48 83 / 10 10 0 20
BZN 35 73 42 83 / 10 10 0 10
WEY 28 63 33 74 / 20 0 0 10
DLN 37 72 44 81 / 10 10 0 10
HVR 38 74 48 80 / 10 0 10 10
LWT 36 70 46 79 / 10 10 0 10
&&
.TFX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
WEATHER.GOV/GREATFALLS
000
FXUS65 KBYZ 192133
AFDBYZ
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BILLINGS MT
333 PM MDT SAT MAY 19 2012
.SHORT TERM...VALID FOR SUN AND MON...
CUMULUS WAS DEVELOPING OVER THE AREA BASED ON VISIBLE SATELLITE
IMAGERY. RADAR IMAGERY ALSO SHOWED POSSIBLE SHOWERS MOVING OFF THE
SW MOUNTAINS. EVENING POPS WERE IN GOOD SHAPE BASED ON THE LATEST
RAPID REFRESH AND WRF...INSTABILITY AND QPF FIELDS. THE SLIGHT
CHANCE OVER THE NE BIG HORNS OVERNIGHT ALSO LOOKED FINE GIVEN THE
TRACK OF THE WAVE MOVING ACROSS THE AREA AND ASSOCIATED MOISTURE.
ANOTHER WAVE WILL MOVE E INTO THE AREA ON SUN. MODEL TIME-HEIGHT
CROSS SECTIONS SHOWED THE MAIN MOISTURE ABOVE 10,000 FT SUN THROUGH
SUN EVENING...WITH DRYING OVERNIGHT. ADDED SLIGHT CHANCE POPS ABOVE
9000 FT AND INCLUDED THUNDER OVER THE WESTERN MOUNTAINS AS SOUNDINGS
SHOWED MID AND UPPER LEVEL INSTABILITY. HIGH TEMPERATURES LOOKED
REASONABLE ON SUN. UPPER RIDGING AND A DRY AIRMASS ON MON WILL
GRADUALLY GIVE WAY TO SW FLOW WITH INCREASING SHORTWAVE ENERGY IN
THE FLOW MON NIGHT. REMOVED MON POPS UNDER THE DRY AIRMASS...AND
TRENDED MON NIGHT POPS DOWN AS THE MOISTURE WILL BE SLOW TO ARRIVE.
RAISED TEMPERATURES ON MON WITH THE AIRMASS MIXING UP TO 600 TO 700
MB. 700 MB TEMPERATURES WILL RANGE FROM +7 TO +10 DEGREES C.
RAISED MIN TEMPERATURES ALL THREE NIGHTS...WITH THE BIGGEST RAISES
ON SUN NIGHT AND MON NIGHT...AS 850 MB TEMPERATURES KEEP CLIMBING
THROUGH THE PERIOD. MON NIGHT SHOULD BE QUITE WARM IN A PREFRONTAL
AIRMASS WITH 850 MB TEMPERATURES REMAINING IN THE LOWER TO MID 20S
DEGREES C THROUGH THE NIGHT OVER THE EASTERN ZONES. ARTHUR
.LONG TERM...VALID FOR TUE...WED...THU...FRI...SAT...
MODEL AGREEMENT CONTINUES TO BE GOOD IN THE OVERALL EVOLUTION OF
THE SYNOPTIC PATTERN FOR THE EXTENDED FORECAST. TUESDAY IS STILL
ON TRACK TO BE THE TRANSITION DAY TO A COOLER AND MORE UNSETTLED
PATTERN. THIS PATTERN WILL PERSIST THROUGH THE END OF THE WEEK
BEFORE THE MODELS SUGGEST A TRANSITION TO SOUTHWESTERLY FLOW BY
FRIDAY AND SATURDAY.
THE INITIAL PACIFIC TROUGH IS STILL ON TARGET TO PUSH A COLD FRONT
ACROSS THE AREA DURING THE DAY ON TUESDAY. THIS WILL USER IN
COOLER TEMPERATURES FROM WEST TO EAST...ECLIPSING THE HIGH
TEMPERATURES IN WESTERN ZONES...BUT LEAVING EASTERN ZONES TO GET
QUITE WARM AHEAD OF THE FRONT. SHOWERS AND THUNDERSTORMS ARE
EXPECTED TO DEVELOP BEHIND THE COLD FRONT AS THE BETTER MOISTURE
AND QG FORCING REACH THE AREA. HAVE INCREASED POPS ON TUESDAY A
BIT TO SHOWCASE THE POTENTIAL PRECIPITATION THREAT AS THE COLD
FRONT MOVES TROUGH.
SCATTERED SHOWERS AND POSSIBLY A FEW THUNDERSTORMS WILL CONTINUE
INTO WEDNESDAY AS DISORGANIZED VORTICITY MAXIMA ROTATE THROUGH THE
MEAN TROUGH AND ACROSS OUR CWA. TEMPERATURES WILL BE MUCH COOLER
AND BELOW AVERAGE ON WEDNESDAY AS 850 TEMPERATURES WILL BE AROUND
+10C ACROSS THE AREA. THE TROUGH CONTINUES TO LINGER OVER THE AREA
ON THURSDAY BEFORE STARTING PULL OUT TOWARD THE EAST. THE GFS
SOLUTION ADVECTS 850 MB TEMPERATURES OF +2 TO +8 C OVER THE AREA
BY THURSDAY AFTERNOON. THE 12Z RUN OF THE ECMWF IS NOT AS COOL ON
THURSDAY AS IT QUICKLY EJECTS THE INITIAL TROUGH TOWARD THE EAST
AND STARTS BUILDING IN THE SOUTHWESTERLY FLOW MORE QUICKLY. THUS
HAVE NOT TOUCHED TEMPERATURES MUCH ON THURSDAY...BUT DID COOL
TEMPERATURES A COUPLE DEGREES ON WEDNESDAY.
THE MODEL AGREEMENT CONTINUES TO BE GOOD FOR DEVELOPING A CUTOFF
LOW OVER THE WESTERN CONUS BY FRIDAY. THIS DEVELOPS SOUTHWESTERLY
FLOW ACROSS OUR AREA ON FRIDAY AND SATURDAY. THE ECMWF IS FASTER
AT DEVELOPING THIS SOLUTION...AND KICKS A WARM FRONT ACROSS THE
AREA ON FRIDAY WHILE THE GFS IS A BIT SLOWER IN THE EVOLUTION AND
KICKS THE WARM FRONT ACROSS THE AREA ON SATURDAY. GIVEN THE
INCREASING CONFIDENCE IN THIS OVERALL SOLUTION HAVE STARTED
INCREASING TEMPERATURES FOR SATURDAY...BUT WILL HAVE TO KEEP AN
EYE ON FRIDAY IF MODELS TREND TOWARD THE FASTER ECMWF SOLUTION.
THIS PATTERN WOULD ALLOW US TO TAP INTO SOME GULF OF MEXICO
MOISTURE AND COULD SET UP A WET MEMORIAL DAY WEEKEND FOR THE AREA.
THE INCREASED POPS BY THE MID-SHIFT FOR FRIDAY AND SATURDAY
CONTINUE TO LOOK GOOD FOR NOW...BUT WILL HAVE TO BE INCREASED IF
MODEL CONFIDENCE CONTINUES TO INCREASE. CHURCH
&&
.AVIATION...
SCATTERED SHOWERS THIS AFTERNOON OVER THE MOUNTAINS AND NEAR KLVM
WILL SPREAD EASTWARD THIS EVENING. AN ISOLATED THUNDERSTORM IS
POSSIBLE. KBIL AND KSHR MAY SEE A FEW CELLS BETWEEN 23Z-03Z
BEFORE ACTIVITY DISSIPATES. CONDITIONS ARE EXPECTED TO REMAIN VFR.
EXPECT CLEARING OVERNIGHT. BORSUM
&&
.PRELIMINARY POINT TEMP/POPS...
SUN MON TUE WED THU FRI SAT
-----------------------------------------------------------
BIL 045/076 052/088 060/076 047/060 044/058 044/061 043/071
20/B 00/U 14/T 44/T 34/W 33/W 33/T
LVM 035/074 045/085 050/066 039/056 037/053 038/056 036/067
20/B 00/U 25/T 54/T 34/W 44/W 34/T
HDN 042/077 049/089 057/079 044/061 043/060 040/062 045/072
20/B 00/B 13/T 43/T 34/W 33/W 33/T
MLS 042/076 053/089 063/083 048/065 046/062 042/064 046/071
00/U 00/B 12/T 43/T 24/W 33/W 33/T
4BQ 042/074 050/087 059/084 045/063 043/061 041/063 047/074
10/B 00/U 02/T 43/T 24/W 33/W 43/T
BHK 037/071 046/085 055/084 050/063 044/061 041/061 047/070
00/U 00/B 12/T 43/T 24/W 33/W 43/T
SHR 038/073 045/085 054/079 041/059 039/057 037/060 043/072
20/B 00/U 03/T 53/T 34/W 33/W 43/T
&&
.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...NONE.
WY...NONE.
&&
$$
WEATHER.GOV/BILLINGS
000
FXUS65 KGGW 192131
AFDGGW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GLASGOW MT
331 PM MDT SAT MAY 19 2012
.SHORT TERM...FOR NORTHEAST MONTANA...TONIGHT THROUGH MONDAY...
WATER VAPOR IMAGERY AND 500 MB HEIGHT FIELD SHOWS A SIMILAR AND
SLIGHTLY LESS ACTIVE PATTERN THAN YESTERDAY. A LOW PRESSURE
CIRCULATION OFF THE SOUTH CAROLINA COAST HAS BECOME THE FIRST
TROPICAL OF THE ATLANTIC HURRICANE SEASON WHILE INTRODUCING SOME
SCATTERED THUNDERSTORMS INTO THE INTERIOR SOUTHEAST. HIGH PRESSURE
CONTINUES TO HOLD SWAY OVER THE LOWER MISSISSIPPI AND OHIO RIVER
VALLEYS. THE SLOW- MOVING UPPER TROUGH WHICH HAS FINALLY EMERGED
ONTO THE CENTRAL HIGH PLAINS CONTINUES TO SPAWN THUNDERSTORMS
THERE. THUNDERSTORMS ARE ALSO SETTING OFF OVER SOUTHERN FLORIDA.
REGIONALLY FOR US...AS THE NORTHERN ROCKIES AND NORTHERN HIGH
PLAINS COMES AWAY FROM THE LARGER UPPER LEVEL TROUGH...ZONAL FLOW
IS OSCILLATING WITH A WEAK TROUGH TO STILL ALLOW PARTLY CLOUDY
SKIES AND A FEW SPRINKLES...ESPECIALLY OVER NORTH CENTRAL MONTANA.
LOCALLY...SURFACE HIGH PRESSURE IS KEEPING SKIES MOSTLY SUNNY OVER
OUR CENTRAL AND EASTERN ZONES...WHILE A WEAK INVERTED SURFACE
TROUGH IS PROVIDING ENOUGH LIFT TO SPREAD SOME MID TO UPPER LEVEL
CLOUDS OVER CENTRAL MONTANA AND INTO OUR FAR WESTERN ZONES THIS
AFTERNOON. TODAY...WITH THE RELATIVELY DRY AIR IN PLACE...I DO NOT
EXPECT THIS INCREASE IN CLOUDINESS TO BRING MUCH MORE THAN SOME
ISOLATED LIGHT VIRGA RAIN SHOWERS OR SPRINKLES TO OUR WESTERN AND
NORTHWESTERN ZONES TODAY AND TONIGHT.
SUNDAY AND MONDAY...WEAK UPPER LEVEL RIDGING TAKES OVER ACROSS
MONTANA AS TEMPERATURES CLIMB INTO THE 70S AND 80S RESPECTFULLY.
THERE MAY BE JUST ENOUGH MID LEVEL MOISTURE TO SET OF SOME AREA
VIRGA SHOWERS OR SPRINKLES AROUND THE PERIMETER EDGES OF OUR
CWA...SIMILAR TO TODAY.
A LARGE AND STRONG UPPER LEVEL TROUGH THEN SPREADS INTO THE
PACIFIC NORTHWEST TOWARD THE END OF THIS SHORT TERM FORECAST
PERIOD...BRINGING A SOUTHWEST FLOW ALOFT AND INCREASED CLOUDINESS TO
OUR REGION. BMICKELSON
.LONG TERM...MONDAY NIGHT THROUGH SATURDAY...
LONG WAVE TROF DIGGING ACROSS THE WESTERN STATES DOMINATES THE
EXTENDED PERIOD. MODELS DIFFERING MAINLY ON WHERE THE MOISTURE
AND ENERGY WILL AT VARIOUS TIMES IN THE EVOLUTION OF THE SYSTEM.
OVERALL MAIN ADJUSTMENT WAS TO BACK OFF SLIGHTLY ON THE POPS WITH
THE SUGGESTED SPLITTING OF THE SYSTEM AND FOCUS OF THE MAIN LOW
OVER THE GREAT BASIN. EBERT
PREVIOUS LONG TERM DISCUSSION...UPPER RIDGE MOVES TO THE EAST
MONDAY NIGHT AND SOUTHWEST FLOW ALOFT WILL PREVAIL AHEAD OF AN
UPPER LOW THAT MOVES INTO THE AREA BY WEDNESDAY. THERE WILL BE A
COLD FRONT MOVING THROUGH EASTERN MONTANA DURING THE DAY ON
TUESDAY. AIR MASS ALONG AND AHEAD OF THE FRONT SHOULD BE UNSTABLE
ENOUGH TO SUPPORT SOME THUNDERSTORMS. MODELS HAVE VARIED ON WHERE
THE BEST INSTABILITY WILL BE. WILL MENTION A CHANCE OF
THUNDERSTORMS.
THE GFS AND ECMWF PLACE THE UPPER LOW DIFFERENTLY ON WEDNESDAY AND
WEDNESDAY NIGHT WITH GFS FAVORING MONTANA AND ECMWF PUTTING THE
LOW IN SASKATCHEWAN. BOTH MODELS HAVE EASTERN MONTANA IN A DRY
SLOT FOR AT LEAST PART OF THE DAY. HOWEVER...THAT WILL ALLOW FOR
DAYTIME HEATING TO DESTABILIZE THE ATMOSPHERE. MAY SEE SOME
SHOWERS AND THUNDERSTORMS DEVELOP AS A RESULT. WILL MENTION A
CHANCE FOR NOW.
THE MODEL DIFFERENCES CONTINUE THURSDAY WITH THE ECMWF KEEPING THE
UPPER LOW IN SASKATCHEWAN AND DRY SLOT OVER EASTERN MONTANA WHILE
THE GFS TRACKS ITS UPPER LOW INTO NORTH DAKOTA AND MANITOBA. WILL
MAINTAIN A CHANCE OF SHOWERS GIVEN THE UNCERTAINTY.
FRIDAY AND SATURDAY...THE NEXT UPPER LOW DIGS SOUTH INTO NORTHERN
CALIFORNIA WITH RIDGE TO THE EAST. MONTANA WILL BE IN A SOMEWHAT
MOIST SOUTHWEST FLOW ALOFT. WILL MAINTAIN A CHANCE OF SHOWERS FOR
NOW. FORRESTER
&&
.AVIATION...
HIGH PRESSURE OVER EASTERN MONTANA WILL BE MOVING OFF THE TO EAST
OVERNIGHT. LEE TROF WILL DEVELOP OVER CENTRAL MONTANA ON SUNDAY
RESULTING IN WINDS TURNING SOUTHEAST. VFR CONDITIONS ARE EXPECTED
THROUGH THE PERIOD. RAE
&&
.GLASGOW WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
WEATHER.GOV/GLASGOW
000
FXUS65 KMSO 192042
AFDMSO
Area Forecast Discussion
National Weather Service Missoula MT
242 PM MDT Sat May 19 2012
.DISCUSSION...
Mild daytime temperatures will be present across western Montana
and north central Idaho through Sunday. A stray shower or two may
develop over the Glacier Park region, however any development will
be of little consequence. Mostly clear skies tonight will allow
valley temperatures to become fairly chilly once again.
Precipitation chances will rapidly increase Sunday night,
marking the beginning a long period of unsettled weather.
Confidence is still high for a strong cold front to begin
affecting northwestern Montana by late Monday afternoon and the
rest of western Montana and central Idaho by Monday evening. The
storm system will have abundant moisture with it allowing the
chances for wetting rains to be area wide. The atmosphere will be
unstable enough for thunderstorms to develop along the cold front
Monday evening. Temperatures will begin to drop Tuesday after the
frontal passage with highs 10-15 degrees below normal.
Low pressure will dominate the western United States for the rest of
the week and possibly into next weekend. There are still a lot of
details that need to be settled with this system, but below
average temperatures with on and off rain showers should be
expected. There is not a distinct dry period in the extended
forecast and this could create issues for outdoor activities and
construction projects that need dry periods.
&&
.AVIATION...
Mid and high level clouds will be present over the northern
Rockies during the next 24 hours. Winds will be fairly
benign during this time as well.
&&
.MSO WATCHES/WARNINGS/ADVISORIES...
MT...None.
ID...None.
&&
$$
dz/lr/jk
Aviation...dz
000
FXUS65 KTFX 191951
AFDTFX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
151 PM MDT SAT MAY 19 2012
.DISCUSSION...
THIS AFTERNOON THROUGH MONDAY EVENING...AXIS OF WEAK UPPER LEVEL
TROF JUST CROSSING THE CONTINENTAL DIVIDE AS OF 2PM. SMALL AREA OF
ASSOCIATED MOISTURE AHEAD OF THE AXIS IS SPREADING SCATTERED MOSTLY
MID-LEVEL CLOUD COVER ACROSS OUR REGION. A FEW OF THE CLOUDS ARE
STARTING TO DEVELOP ENOUGH TO SHOW UP AS A LIGHT RAIN SHOWER ON
RADAR IMAGERY ALONG PORTIONS OF THE HILINE AND OVER FAR SOUTHWEST MT
AROUND DILLON/WEST YELLOWSTONE. AS THE AXIS MOVES OFF THE MTNS AND
INTO THE PLAINS THE COVERAGE OF THE SHOWERS WILL EXPAND SLIGHTLY
MAINLY OVER SOUTHWEST AND PARTS OF CENTRAL MT. ONLY LIGHT RAINFALL
AMOUNTS ARE EXPECTED FROM THIS ACTIVITY. MODELS REMAIN IN CLOSE
AGREEMENT THAT THE TROF AXIS WILL EXIT INTO ERN MT TONIGHT AND UPPER
LEVEL RIDGE CURRENTLY ALONG THE PACNW COAST WILL BUILD INTO THE NRN
ROCKIES TOMORROW...BRINGING MOSTLY FAIR SKIES AND TEMPERATURES
WARMING INTO THE UPPER 60S TO MID 70S. THE RIDGE PERSISTS UNTIL
AROUND MIDDAY MONDAY THEN SLIDES EASTWARD AS LEADING EDGE OF A DEEP
LOW PRESSURE SYSTEM IN THE ERN PACIFIC MOVES INTO WRN MT. MOISTURE
GRADUALLY BUILDS INTO THE REGION WITH SCATTERED SHOWERS AND
THUNDERSTORMS DEVELOPING ON MON AFTN/EVE MAINLY ALONG/WEST OF THE
INTERSTATE 15 CORRIDOR. WARM SOUTHWESTERLY FLOW ON THE WEST SIDE OF
THE DEPARTING RIDGE WILL PUSH TEMPS INTO THE UPPER 70S TO LOW 80S ON
MON BEFORE THE PRECIPITATION DEVELOPS.
WARANAUSKAS
MONDAY NIGHT THROUGH SATURDAY...A BROAD UPPER-LEVEL TROUGH OF LOW
PRESSURE AND ASSOCIATED SURFACE COLD FRONT WILL MOVE INTO THE
PACIFIC NORTHWEST MONDAY NIGHT. SOUTHWEST FLOW AND AMPLE PACIFIC
MOISTURE AHEAD OF THIS TROUGH WILL BRING INCREASING PRECIPITATION
CHANCES TO THE FORECAST AREA MONDAY NIGHT AND TUESDAY. THE COLD
FRONT IS EXPECTED TO MOVE THROUGH THE STATE ON TUESDAY WITH
WIDESPREAD PRECIPITATION AND COOLING TEMPERATURES EXPECTED. MODELS
ARE INDICATING THAT THIS BROAD TROUGH WILL REMAIN OVER THE WESTERN
U.S. THROUGH THE REMAINDER OF THE WEEK AND POSSIBLY INTO NEXT
WEEKEND YIELDING UNSETTLED AND COOL CONDITIONS OVER THE NORTHERN
ROCKIES. SEVERAL SHORTWAVES WILL PROPAGATE THROUGH THE
TROUGH...HOWEVER CONFIDENCE IS LOW REGARDING THE TIMING OF EACH OF
THESE WAVES AS WELL AS PRECIPITATION AMOUNTS. ON THURSDAY...THE GFS
BRINGS A CLOSED AREA OF LOW PRESSURE OVER MONTANA WHILE THE ECMWF
KEEPS A CLOSED LOW ALONG THE WEST COAST. BOTH SOLUTIONS SUGGEST
PRECIPITATION OVER THE FORECAST AREA...HOWEVER EACH SOLUTION DIFFERS
ON WHICH AREAS CAN EXPECT THE MOST PRECIPITATION. SO FOR NOW HAVE
KEPT CHANCE POPS IN THE PLAINS WITH LIKELY POPS IN THE MOUNTAINS FOR
THE MIDDLE PART OF NEXT WEEK AND THEN CHANCE POPS OVER THE ENTIRE
AREA FOR THE LATTER HALF OF THE FORECAST PERIOD GIVEN THE
UNCERTAINTY. IN ADDITION...TEMPERATURES COULD BE AROUND 10 DEGREES
BELOW SEASONAL AVERAGES WITH SNOW LEVELS LOWERING TO NEAR 6000 FEET
BY THURSDAY. OVERALL...EACH MODEL SOLUTION INDICATES THAT A WETTER
AND COOLER PATTERN IS EXPECTED FOR MOST OF NEXT WEEK AND POTENTIALLY
INTO THE MEMORIAL DAY HOLIDAY WEEKEND. MLV
&&
.AVIATION...
UPDATED 1747Z.
EXPECT MAINLY VFR CONDITIONS AND LIGHT WINDS THIS AFTERNOON. A
WEATHER DISTURBANCE WILL BRING A FEW SHOWERS TO SOUTHWEST MONTANA
THIS AFTERNOON AND EVENING. EXPECT LOW CEILINGS...REDUCED
VISIBILITIES...AND GUSTY WINDS NEAR THUNDERSTORMS. MERCER
&&
.PRELIMINARY POINT TEMPS/POPS...
GTF 40 74 50 80 / 10 10 0 20
CTB 35 72 46 74 / 10 10 20 20
HLN 39 75 48 83 / 10 10 0 20
BZN 35 73 42 83 / 10 10 0 10
WEY 28 63 33 74 / 20 0 0 10
DLN 37 72 44 81 / 10 10 0 10
HVR 38 74 48 80 / 10 0 10 10
LWT 36 70 46 79 / 10 10 0 10
&&
.TFX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...WARANAUSKAS
LONG TERM...MERCER
AVIATION...MLS
WEATHER.GOV/GREATFALLS
000
FXUS65 KTFX 191747
AFDTFX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
1147 AM MDT SAT MAY 19 2012
.UPDATE TO AVIATION...
.UPDATE...
FORECAST IN GOOD SHAPE AT THIS POINT. WEAK TROF DISCUSSED BELOW
CURRENTLY OVER THE CONTINENTAL DIVIDE AND WILL MOVE ACROSS OUR
REGION THIS AFTN/EVE. LATEST FORECAST MODELS INDICATE ISOLATED TO
SCATTERED SHOWERS ALONG THE ROCKY MTN FRONT...WITH A SLIGHT CHANCE
FOR A SHORT-LIVED THUNDERSTORM OR TWO OVER THE LITTLE/BIG BELT MTNS
AND THE MTNS OVER SOUTHWEST MT. MADE SOME MINOR ADJUSTMENTS TO SKY
COVER AND EXPECTED HIGH TEMPERATURES AND ADDED MENTION OF THUNDER IN
FOR THE NOTED MTN AREAS.
WARANAUSKAS
.DISCUSSION...
TODAY THROUGH MONDAY...MODELS ARE IN AGREEMENT IN FORECASTING A
WEAK WEATHER DISTURBANCE ALOFT TO MOVE SOUTHEAST THROUGH THE
FORECAST AREA LATER THIS AFTERNOON THROUGH THIS EVENING. ALTHOUGH
THERE IS NOT MUCH LIFT WITH THE DISTURBANCE..WEAK INSTABILITY AND
TERRAIN EFFECTS COULD GENERATE A FEW SHOWERS MAINLY OVER THE
MOUNTAINS. LATE TONIGHT INTO EARLY MONDAY THE AREA WILL BE UNDER
THE INFLUENCE OF BUILDING HIGH PRESSURE ALOFT WHICH WILL KEEP THE
FORECAST AREA DRY. THE EXCEPTION TO THIS COULD BE IN THE NORTHWEST
WHERE INCREASING MOISTURE COULD LEAD TO THREAT OF SHOWERS SUNDAY
NIGHT. SOME GUIDANCE SUGGESTS THE THREAT OF SHOWERS WILL HOLD OFF
UNTIL MONDAY. BY LATE MONDAY THE FORECAST AREA WILL BE SOUTHWEST
FLOW ALOFT WITH INCREASED MOISTURE AND LIKELY WEAK INSTABILITY.
SHOULD SEE AT LEAST SCATTERED SHOWERS/THUNDERSTORMS OVER THE
WESTERN MOUNTAINS AND COULD POSSIBLY SEE A FEW SHOWERS FARTHER
EAST. PREVIOUS FORECAST OF WARMING TEMPERATURES TODAY THROUGH MONDAY
LOOKS GOOD WITH THE FORECAST OF A BUILDING RIDGE. BLANK
MONDAY NIGHT THROUGH SATURDAY...A BROAD UPPER-LEVEL TROUGH OF LOW
PRESSURE AND ASSOCIATED SURFACE COLD FRONT WILL MOVE INTO THE
PACIFIC NORTHWEST MONDAY NIGHT. SOUTHWEST FLOW AND AMPLE PACIFIC
MOISTURE AHEAD OF THIS TROUGH WILL BRING INCREASING PRECIPITATION
CHANCES TO THE FORECAST AREA MONDAY NIGHT AND TUESDAY. THE COLD
FRONT IS EXPECTED TO MOVE THROUGH THE STATE ON TUESDAY WITH
WIDESPREAD PRECIPITATION AND COOLING TEMPERATURES EXPECTED. MODELS
ARE INDICATING THAT THIS BROAD TROUGH WILL REMAIN OVER THE WESTERN
U.S. THROUGH THE REMAINDER OF THE WEEK AND POSSIBLY INTO NEXT
WEEKEND YIELDING UNSETTLED AND COOL CONDITIONS OVER THE NORTHERN
ROCKIES. SEVERAL SHORTWAVES WILL PROPAGATE THROUGH THE
TROUGH...HOWEVER CONFIDENCE IS LOW REGARDING THE TIMING OF EACH OF
THESE WAVES AS WELL AS PRECIPITATION AMOUNTS. ON THURSDAY...THE GFS
BRINGS A CLOSED AREA OF LOW PRESSURE OVER MONTANA WHILE THE ECMWF
KEEPS A CLOSED LOW ALONG THE WEST COAST. BOTH SOLUTIONS SUGGEST
PRECIPITATION OVER THE FORECAST AREA...HOWEVER EACH SOLUTION DIFFERS
ON WHICH AREAS CAN EXPECT THE MOST PRECIPITATION. SO FOR NOW HAVE
KEPT CHANCE POPS IN THE PLAINS WITH LIKELY POPS IN THE MOUNTAINS FOR
THE MIDDLE PART OF NEXT WEEK AND THEN CHANCE POPS OVER THE ENTIRE
AREA FOR THE LATTER HALF OF THE FORECAST PERIOD GIVEN THE
UNCERTAINTY. IN ADDITION...TEMPERATURES COULD BE AROUND 10 DEGREES
BELOW SEASONAL AVERAGES WITH SNOW LEVELS LOWERING TO NEAR 6000 FEET
BY THURSDAY. OVERALL...EACH MODEL SOLUTION INDICATES THAT A WETTER
AND COOLER PATTERN IS EXPECTED FOR MOST OF NEXT WEEK AND POTENTIALLY
INTO THE MEMORIAL DAY HOLIDAY WEEKEND. MLV
&&
.AVIATION...
UPDATED 1747Z.
EXPECT MAINLY VFR CONDITIONS AND LIGHT WINDS THIS AFTERNOON. A
WEATHER DISTURBANCE WILL BRING A FEW SHOWERS TO SOUTHWEST MONTANA
THIS AFTERNOON AND EVENING. EXPECT LOW CEILINGS...REDUCED
VISIBILITIES...AND GUSTY WINDS NEAR THUNDERSTORMS. MERCER
&&
.PRELIMINARY POINT TEMPS/POPS...
GTF 66 40 74 50 / 10 10 10 0
CTB 62 35 72 46 / 10 10 10 20
HLN 66 39 75 48 / 10 10 10 0
BZN 64 35 73 42 / 10 10 10 0
WEY 55 28 63 33 / 20 20 0 0
DLN 63 37 72 44 / 10 10 10 0
HVR 66 38 74 48 / 0 0 0 10
LWT 60 36 70 46 / 10 10 10 0
&&
.TFX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...BLANK
LONG TERM...MLS
AVIATION...BLANK
WEATHER.GOV/GREATFALLS
000
FXUS65 KBYZ 191548
AFDBYZ
AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE BILLINGS MT
948 AM MDT SAT MAY 19 2012
.SHORT TERM...VALID FOR TDY AND SUN...
UPDATE TO FORECAST AND FIRE WEATHER FORECAST THIS MORNING.
PRECIPITATION HAD DEPARTED SE MT PER RADAR IMAGERY. MODELS DID NOT
SHOW ANY REDEVELOPMENT THIS MORNING DESPITE WEAK WAVES MOVING
THROUGH THIS AREA. VISIBLE SATELLITE IMAGERY SHOWED THE RIVER VALLEY
FOG HAD DISSIPATED SO REMOVED IT FROM THE FORECAST. FOR CONVECTION
CHANCES THIS AFTERNOON AND EVENING...CHECKED THE RAPID
REFRESH...SREF AND NEW WRF WHICH SHOWED SOME QPF OVER THE WESTERN
ZONES AND OVER THE NE BIG HORNS AS A SHORTWAVE MOVES INTO THE AREA
FROM THE PACIFIC NW. SURFACE CAPE WAS FORECAST TO BE ABOVE 500 J/KG
OVER THE W PER THE SREF...AND WRF SOUNDINGS HAD A MICROBURST
APPEARANCE IN THIS AREA. THUS HAVE EXPANDED SLIGHT CHANCES FOR
PRECIPITATION N INTO WHEATLAND COUNTY. CAN EXPAND FURTHER IF
DEVELOPMENT TRENDS THIS AFTERNOON INDICATE THE NEED FOR IT. ADDED
THUNDER TO THE W AS WELL.
MOST HIGH TEMPERATURES LOOKED ON TRACK FOR THE AFTERNOON. DID RAISE
THEM A BIT OVER THE SHERIDAN AREA AND NW ZONES BASED ON CURRENT
READINGS AND EXPECTED MIXDOWNS. ARTHUR
.LONG TERM...VALID FOR MON...TUE...WED...THU...FRI...
MODEL AGREEMENT IS RELATIVELY GOOD THROUGH THE PERIOD WITH BROAD
TROUGH MOVING INTO PACIFIC NORTHWEST TUESDAY DRIVING A PACIFIC
COLD FRONT ACROSS THE AREA TUESDAY NIGHT INTO EARLY WEDNESDAY.
UPPER TROUGH DEEPENS OVER THE NORTHERN ROCKIES WEDNESDAY THROUGH
THURSDAY...LEAVING THE AREA COOL AND UNSETTLED. MEANWHILE...MODELS
AGREE VERY WELL ON A CUTOFF LOW SETTLING OVER CALIFORNIA BY FRIDAY
NIGHT...PLACING THE NORTHERN ROCKIES UNDER SOUTHWEST FLOW ALOFT
AND INCREASINGLY DIFLUENT FLOW. THIS OPENS THE DOOR FOR
POTENTIALLY WET MEMORIAL DAY WEEKEND AS ALL MODELS SUGGEST
EJECTING SHORTWAVE TROUGHS NORTHEASTWARD TOWARD NORTHERN ROCKIES.
THIS WILL BEAR WATCHING...BUT MODEL AGREEMENT WITH THIS FEATURE IS
PARTICULARLY NOTEWORTHY CONSIDERING THE FORECAST RANGE AND THE
GENERAL PREDICTABILITY CHALLENGES DURING THIS TIME OF YEAR AT
THOSE RANGES.
SPECIFICALLY...BEGAN TO NUDGE PRECIPITATION CHANCES UPWARD A BIT
BEGINNING TUESDAY NIGHT AND RUNNING THROUGH THE REST OF THE
PERIOD. BEST THREATS FOR PRECIPITATION ACROSS THE AREA CERTAINLY
APPEAR TO BE WEDNESDAY AND THURSDAY. ALSO TRENDED HIGH
TEMPERATURES 5 TO 7 DEGREES COOLER WEDNESDAY THROUGH FRIDAY IN
RESPONSE TO GOOD MODEL AGREEMENT ON THIS COOLING TREND. MEIER
&&
.AVIATION...
VFR CONDITIONS THIS MORNING WITH SHOWER AND THUNDERSTORMS
EXPECTED TO DEVELOP EARLY AFTERNOON ACROSS WESTERN AREAS IMPACTING
KLVM AROUND 20Z. THESE SHOWERS AND THUNDERSTORMS WILL SPREAD
EASTWARD DURING THE LATE AFTERNOON HOURS POSSIBLY REACHING KSHR
AND KBIL AROUND 00Z. BORSUM
&&
.PRELIMINARY POINT TEMP/POPS...
TDY SUN MON TUE WED THU FRI
-------------------------------------------------------
BIL 064 043/076 052/087 058/076 047/060 044/060 044/061
1/U 20/B 00/B 13/T 44/T 34/W 33/W
LVM 060 035/074 043/084 049/070 039/056 037/056 038/056
2/T 20/B 00/B 35/T 44/T 33/W 44/W
HDN 065 039/077 048/089 053/079 044/061 043/061 040/062
1/U 20/B 00/B 13/T 44/T 33/W 33/W
MLS 066 041/076 052/089 058/083 048/065 046/062 042/064
0/B 00/U 00/B 13/T 44/T 34/W 33/W
4BQ 064 039/074 049/087 053/084 045/063 043/062 041/063
0/B 10/B 00/U 03/T 44/T 34/W 33/W
BHK 064 038/071 046/084 054/083 050/063 044/060 041/061
0/N 00/U 00/B 03/T 44/T 34/W 33/W
SHR 066 037/073 044/085 050/079 041/059 039/059 037/060
1/B 20/B 00/U 03/T 54/T 44/W 33/W
&&
.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...NONE.
WY...NONE.
&&
$$
WEATHER.GOV/BILLINGS
000
FXUS65 KGGW 191535 AAA
AFDGGW
AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE GLASGOW MT
935 AM MDT SAT MAY 19 2012
.SHORT TERM...FOR NORTHEAST MONTANA...TODAY THROUGH MONDAY...
SENT AN UPDATE TO THE FORECAST THIS MORNING TO MORE ACCURATELY
REFLECT THE LINGERING CLOUDS OVER OUR SOUTHEASTERN ZONES. SHORT
TERM MODELS ALSO WERE IN VERY GOOD AGREEMENT BRINGING IN SOME KIND
OF LIGHT PRECIP TO OUR NORTHWESTERN ZONES. GIVEN THE HIGH PRESSURE
AND DRY AIR...PUT IN SOME SPRINKLES FOR THIS AREA LATER THIS
AFTERNOON. UPPER LEVEL FLOW PATTERN STILL BRINGS A VERY WEAK
TROUGH THROUGH THE CWA TODAY AND TONIGHT BEFORE THE RIDGE BUILDS
IN TOMORROW. BMICKELSON
PREVIOUS SHORT TERM DISCUSSION...THE UPPER LEVEL LOW IN CENTRAL
ALBERTA AND SASKATCHEWAN THAT DROVE THE SHORTWAVE DISTURBANCE
THROUGH THE REGION ON FRIDAY WILL DRIVE ANOTHER MUCH WEAKER
SHORTWAVE DISTURBANCE THROUGH MONTANA TODAY AND TONIGHT. THE MAIN
EFFECT OF THIS DISTURBANCE WILL BE TO NUDGE A COLD BOUNDARY SOUTH
AGAINST NORTHEAST MONTANA. THIS WILL MAINTAIN A COOLING AFFECT SO
THAT TEMPERATURES WILL TREND NEAR OR JUST BELOW NORMAL TODAY.
EXCEPT FOR A FEW LINGERING RADAR ECHOES ALL SHOWER ACTIVITY HAS
MOVED TO THE EAST THIS MORNING. HOWEVER THE SHORTWAVE SHOULD
PRODUCE SOME MID-LEVEL CLOUDS. HIGH SURFACE PRESSURE SHOULD QUIET
DOWN THE WINDS.
THE REMAINDER OF THE SHORT TERM WILL SEE AN UPPER RIDGE AXIS MOVE
FROM THE WEST COAST TO MONTANA THROUGH MONDAY FOR CONTINUING DRY
CONDITIONS. DURING THAT PERIOD THICKNESS HEIGHTS WILL RISE FROM
AROUND 550DM TO 570DM. TEMPERATURES WILL TREND TO AROUND 15F TO
20F ABOVE NORMAL BY MONDAY AFTERNOON. SUNDAY NIGHT A WEST COAST
TROUGH WILL BE EJECTING MOISTURE IN THE DIRECTION OF THE NORTHERN
ROCKIES. WITH A DEVELOPING LEE SURFACE TROUGH EXPECT SKY COVER TO
BEGIN TO INCREASE FOR SUNDAY EVENING AND MONDAY.
THE POSSIBILITY OF INCREASING CLOUD COVER EARLY SUNDAY EVENING
COULD INTERFERE WITH VIEWING THE PARTIAL SOLAR ECLIPSE WHEN THE
MOON MOVES IN FRONT OF THE SUN. BUT THERE ARE CURRENTLY DIFFERENCES
IN TIMING AMONG THE MODELS...SO SHOULD GET A BETTER IDEA OF CLOUD
COVER THE CLOSER TO THE SOLAR EVENT WE GET WITH LATER MODEL RUNS.
SCT
.LONG TERM...MONDAY NIGHT THROUGH SATURDAY...
UPPER RIDGE MOVES TO THE EAST MONDAY NIGHT AND SOUTHWEST FLOW
ALOFT WILL PREVAIL AHEAD OF AN UPPER LOW THAT MOVES INTO THE AREA
BY WEDNESDAY. THERE WILL BE A COLD FRONT MOVING THROUGH EASTERN
MONTANA DURING THE DAY ON TUESDAY. AIRMASS ALONG AND AHEAD OF THE
FRONT SHOULD BE UNSTABLE ENOUGH TO SUPPORT SOME THUNDERSTORMS.
MODELS HAVE VARIED ON WHERE THE BEST INSTABILITY WILL BE. WILL
MENTION A CHANCE OF THUNDERSTORMS.
THE GFS AND ECMWF PLACE THE UPPER LOW DIFFERENTLY ON WEDNESDAY AND
WEDNESDAY NIGHT WITH GFS FAVORING MONTANA AND ECMWF PUTTING THE
LOW IN SASKATCHEWAN. BOTH MODELS HAVE EASTERN MONTANA IN A DRY
SLOT FOR AT LEAST PART OF THE DAY. HOWEVER...THAT WILL ALLOW FOR
DAYTIME HEATING TO DESTABILIZE THE ATMOSPHERE. MAY SEE SOME
SHOWERS AND THUNDERSTORMS DEVELOP AS A RESULT. WILL MENTION A
CHANCE FOR NOW.
THE MODEL DIFFERENCES CONTINUE THURSDAY WITH THE ECMWF KEEPING THE
UPPER LOW IN SASKATCHEWAN AND DRY SLOT OVER EASTERN MONTANA WHILE
THE GFS TRACKS ITS UPPER LOW INTO NORTH DAKOTA AND MANITOBA. WILL
MAINTAIN A CHANCE OF SHOWERS GIVEN THE UNCERTAINTY.
FRIDAY AND SATURDAY...THE NEXT UPPER LOW DIGS SOUTH INTO NORTHERN
CALIFORNIA WITH RIDGE TO THE EAST. MONTANA WILL BE IN A SOMEWHAT
MOIST SOUTHWEST FLOW ALOFT. WILL MAINTAIN A CHANCE OF SHOWERS FOR
NOW. FORRESTER
&&
.AVIATION...
A FEW LOW CLOUDS WITH CEILINGS AS LOW AS 1000 FEET WILL MOVE
OUT OF NORTHEAST MONTANA THIS MORNING. OTHERWISE...LOOK FOR
MOSTLY CLEAR SKIES TODAY AND TONIGHT AS A HIGH PRESSURE SYSTEM
BUILDS INTO THE AREA.
&&
.GLASGOW WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
WEATHER.GOV/GLASGOW
000
FXUS65 KTFX 191522
AFDTFX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
920 AM MDT SAT MAY 19 2012
.UPDATE...
FORECAST IN GOOD SHAPE AT THIS POINT. WEAK TROF DISCUSSED BELOW
CURRENTLY OVER THE CONTINENTAL DIVIDE AND WILL MOVE ACROSS OUR
REGION THIS AFTN/EVE. LATEST FORECAST MODELS INDICATE ISOLATED TO
SCATTERED SHOWERS ALONG THE ROCKY MTN FRONT...WITH A SLIGHT CHANCE
FOR A SHORT-LIVED THUNDERSTORM OR TWO OVER THE LITTLE/BIG BELT MTNS
AND THE MTNS OVER SOUTHWEST MT. MADE SOME MINOR ADJUSTMENTS TO SKY
COVER AND EXPECTED HIGH TEMPERATURES AND ADDED MENTION OF THUNDER IN
FOR THE NOTED MTN AREAS.
WARANAUSKAS
.DISCUSSION...
TODAY THROUGH MONDAY...MODELS ARE IN AGREEMENT IN FORECASTING A
WEAK WEATHER DISTURBANCE ALOFT TO MOVE SOUTHEAST THROUGH THE
FORECAST AREA LATER THIS AFTERNOON THROUGH THIS EVENING. ALTHOUGH
THERE IS NOT MUCH LIFT WITH THE DISTURBANCE..WEAK INSTABILITY AND
TERRAIN EFFECTS COULD GENERATE A FEW SHOWERS MAINLY OVER THE
MOUNTAINS. LATE TONIGHT INTO EARLY MONDAY THE AREA WILL BE UNDER
THE INFLUENCE OF BUILDING HIGH PRESSURE ALOFT WHICH WILL KEEP THE
FORECAST AREA DRY. THE EXCEPTION TO THIS COULD BE IN THE NORTHWEST
WHERE INCREASING MOISTURE COULD LEAD TO THREAT OF SHOWERS SUNDAY
NIGHT. SOME GUIDANCE SUGGESTS THE THREAT OF SHOWERS WILL HOLD OFF
UNTIL MONDAY. BY LATE MONDAY THE FORECAST AREA WILL BE SOUTHWEST
FLOW ALOFT WITH INCREASED MOISTURE AND LIKELY WEAK INSTABILITY.
SHOULD SEE AT LEAST SCATTERED SHOWERS/THUNDERSTORMS OVER THE
WESTERN MOUNTAINS AND COULD POSSIBLY SEE A FEW SHOWERS FARTHER
EAST. PREVIOUS FORECAST OF WARMING TEMPERATURES TODAY THROUGH MONDAY
LOOKS GOOD WITH THE FORECAST OF A BUILDING RIDGE. BLANK
MONDAY NIGHT THROUGH SATURDAY...A BROAD UPPER-LEVEL TROUGH OF LOW
PRESSURE AND ASSOCIATED SURFACE COLD FRONT WILL MOVE INTO THE
PACIFIC NORTHWEST MONDAY NIGHT. SOUTHWEST FLOW AND AMPLE PACIFIC
MOISTURE AHEAD OF THIS TROUGH WILL BRING INCREASING PRECIPITATION
CHANCES TO THE FORECAST AREA MONDAY NIGHT AND TUESDAY. THE COLD
FRONT IS EXPECTED TO MOVE THROUGH THE STATE ON TUESDAY WITH
WIDESPREAD PRECIPITATION AND COOLING TEMPERATURES EXPECTED. MODELS
ARE INDICATING THAT THIS BROAD TROUGH WILL REMAIN OVER THE WESTERN
U.S. THROUGH THE REMAINDER OF THE WEEK AND POSSIBLY INTO NEXT
WEEKEND YIELDING UNSETTLED AND COOL CONDITIONS OVER THE NORTHERN
ROCKIES. SEVERAL SHORTWAVES WILL PROPAGATE THROUGH THE
TROUGH...HOWEVER CONFIDENCE IS LOW REGARDING THE TIMING OF EACH OF
THESE WAVES AS WELL AS PRECIPITATION AMOUNTS. ON THURSDAY...THE GFS
BRINGS A CLOSED AREA OF LOW PRESSURE OVER MONTANA WHILE THE ECMWF
KEEPS A CLOSED LOW ALONG THE WEST COAST. BOTH SOLUTIONS SUGGEST
PRECIPITATION OVER THE FORECAST AREA...HOWEVER EACH SOLUTION DIFFERS
ON WHICH AREAS CAN EXPECT THE MOST PRECIPITATION. SO FOR NOW HAVE
KEPT CHANCE POPS IN THE PLAINS WITH LIKELY POPS IN THE MOUNTAINS FOR
THE MIDDLE PART OF NEXT WEEK AND THEN CHANCE POPS OVER THE ENTIRE
AREA FOR THE LATTER HALF OF THE FORECAST PERIOD GIVEN THE
UNCERTAINTY. IN ADDITION...TEMPERATURES COULD BE AROUND 10 DEGREES
BELOW SEASONAL AVERAGES WITH SNOW LEVELS LOWERING TO NEAR 6000 FEET
BY THURSDAY. OVERALL...EACH MODEL SOLUTION INDICATES THAT A WETTER
AND COOLER PATTERN IS EXPECTED FOR MOST OF NEXT WEEK AND POTENTIALLY
INTO THE MEMORIAL DAY HOLIDAY WEEKEND. MLV
&&
.AVIATION...
UPDATED 1120Z.
EXPECT VFR CONDITIONS HOWEVER THERE WILL BE A THREAT OF IFR CEILINGS
AND VISIBILITIES AT KLWT AND POSSIBLY KHVR UNTIL 15Z THIS MORNING.
THINK THE THREAT IS LOW ENOUGH TO NOT MENTION IN THE TAFS. A WEATHER
DISTURBANCE WILL BRING A FEW SHOWERS TO CENTRAL AND SOUTHWEST
MONTANA THIS AFTERNOON AND EVENING. THESE SHOULD MAINLY AFFECT THE
MOUNTAINS. AT THIS TIME DO NOT THINK THERE WILL BE ENOUGH
INSTABILITY FOR THUNDERSTORMS BUT WOULD NOT BE SURPRISED TO SEE A
THUNDERSTORM OR TWO. WINDS ARE EXPECTED TO BE LIGHT TODAY AND
CONFIDENCE IN FORECAST WIND DIRECTIONS IS ESPECIALLY LOW. BLANK
&&
.PRELIMINARY POINT TEMPS/POPS...
GTF 66 40 74 50 / 10 10 10 0
CTB 62 35 72 46 / 10 10 10 20
HLN 66 39 75 48 / 10 10 10 0
BZN 64 35 73 42 / 10 10 10 0
WEY 55 28 63 33 / 20 20 0 0
DLN 63 37 72 44 / 10 10 10 0
HVR 66 38 74 48 / 0 0 0 10
LWT 60 36 70 46 / 10 10 10 0
&&
.TFX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...BLANK
LONG TERM...MLS
AVIATION...BLANK
WEATHER.GOV/GREATFALLS
000
FXUS65 KTFX 191119
AFDTFX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
520 AM MDT SAT MAY 19 2012
.DISCUSSION...
TODAY THROUGH MONDAY...MODELS ARE IN AGREEMENT IN FORECASTING A
WEAK WEATHER DISTURBANCE ALOFT TO MOVE SOUTHEAST THROUGH THE
FORECAST AREA LATER THIS AFTERNOON THROUGH THIS EVENING. ALTHOUGH
THERE IS NOT MUCH LIFT WITH THE DISTURBANCE..WEAK INSTABILITY AND
TERRAIN EFFECTS COULD GENERATE A FEW SHOWERS MAINLY OVER THE
MOUNTAINS. LATE TONIGHT INTO EARLY MONDAY THE AREA WILL BE UNDER
THE INFLUENCE OF BUILDING HIGH PRESSURE ALOFT WHICH WILL KEEP THE
FORECAST AREA DRY. THE EXCEPTION TO THIS COULD BE IN THE NORTHWEST
WHERE INCREASING MOISTURE COULD LEAD TO THREAT OF SHOWERS SUNDAY
NIGHT. SOME GUIDANCE SUGGESTS THE THREAT OF SHOWERS WILL HOLD OFF
UNTIL MONDAY. BY LATE MONDAY THE FORECAST AREA WILL BE SOUTHWEST
FLOW ALOFT WITH INCREASED MOISTURE AND LIKELY WEAK INSTABILITY.
SHOULD SEE AT LEAST SCATTERED SHOWERS/THUNDERSTORMS OVER THE
WESTERN MOUNTAINS AND COULD POSSIBLY SEE A FEW SHOWERS FARTHER
EAST. PREVIOUS FORECAST OF WARMING TEMPERATURES TODAY THROUGH MONDAY
LOOKS GOOD WITH THE FORECAST OF A BUILDING RIDGE. BLANK
MONDAY NIGHT THROUGH SATURDAY...A BROAD UPPER-LEVEL TROUGH OF LOW
PRESSURE AND ASSOCIATED SURFACE COLD FRONT WILL MOVE INTO THE
PACIFIC NORTHWEST MONDAY NIGHT. SOUTHWEST FLOW AND AMPLE PACIFIC
MOISTURE AHEAD OF THIS TROUGH WILL BRING INCREASING PRECIPITATION
CHANCES TO THE FORECAST AREA MONDAY NIGHT AND TUESDAY. THE COLD
FRONT IS EXPECTED TO MOVE THROUGH THE STATE ON TUESDAY WITH
WIDESPREAD PRECIPITATION AND COOLING TEMPERATURES EXPECTED. MODELS
ARE INDICATING THAT THIS BROAD TROUGH WILL REMAIN OVER THE WESTERN
U.S. THROUGH THE REMAINDER OF THE WEEK AND POSSIBLY INTO NEXT
WEEKEND YIELDING UNSETTLED AND COOL CONDITIONS OVER THE NORTHERN
ROCKIES. SEVERAL SHORTWAVES WILL PROPAGATE THROUGH THE
TROUGH...HOWEVER CONFIDENCE IS LOW REGARDING THE TIMING OF EACH OF
THESE WAVES AS WELL AS PRECIPITATION AMOUNTS. ON THURSDAY...THE GFS
BRINGS A CLOSED AREA OF LOW PRESSURE OVER MONTANA WHILE THE ECMWF
KEEPS A CLOSED LOW ALONG THE WEST COAST. BOTH SOLUTIONS SUGGEST
PRECIPITATION OVER THE FORECAST AREA...HOWEVER EACH SOLUTION DIFFERS
ON WHICH AREAS CAN EXPECT THE MOST PRECIPITATION. SO FOR NOW HAVE
KEPT CHANCE POPS IN THE PLAINS WITH LIKELY POPS IN THE MOUNTAINS FOR
THE MIDDLE PART OF NEXT WEEK AND THEN CHANCE POPS OVER THE ENTIRE
AREA FOR THE LATTER HALF OF THE FORECAST PERIOD GIVEN THE
UNCERTAINTY. IN ADDITION...TEMPERATURES COULD BE AROUND 10 DEGREES
BELOW SEASONAL AVERAGES WITH SNOW LEVELS LOWERING TO NEAR 6000 FEET
BY THURSDAY. OVERALL...EACH MODEL SOLUTION INDICATES THAT A WETTER
AND COOLER PATTERN IS EXPECTED FOR MOST OF NEXT WEEK AND POTENTIALLY
INTO THE MEMORIAL DAY HOLIDAY WEEKEND. MLV
&&
.AVIATION...
UPDATED 1120Z.
EXPECT VFR CONDITIONS HOWEVER THERE WILL BE A THREAT OF IFR CEILINGS
AND VISIBILITIES AT KLWT AND POSSIBLY KHVR UNTIL 15Z THIS MORNING.
THINK THE THREAT IS LOW ENOUGH TO NOT MENTION IN THE TAFS. A WEATHER
DISTURBANCE WILL BRING A FEW SHOWERS TO CENTRAL AND SOUTHWEST
MONTANA THIS AFTERNOON AND EVENING. THESE SHOULD MAINLY AFFECT THE
MOUNTAINS. AT THIS TIME DO NOT THINK THERE WILL BE ENOUGH
INSTABILITY FOR THUNDERSTORMS BUT WOULD NOT BE SURPRISED TO SEE A
THUNDERSTORM OR TWO. WINDS ARE EXPECTED TO BE LIGHT TODAY AND
CONFIDENCE IN FORECAST WIND DIRECTIONS IS ESPECIALLY LOW. BLANK
&&
.PRELIMINARY POINT TEMPS/POPS...
GTF 66 40 74 50 / 10 10 10 0
CTB 62 35 72 46 / 10 10 10 20
HLN 66 39 75 48 / 10 10 10 0
BZN 64 35 73 42 / 10 10 10 0
WEY 55 28 63 33 / 20 20 0 0
DLN 63 37 72 44 / 10 10 10 0
HVR 66 38 74 48 / 0 0 0 10
LWT 60 36 70 46 / 10 10 10 0
&&
.TFX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...BLANK
LONG TERM...MLS
AVIATION...BLANK
WEATHER.GOV/GREATFALLS
000
FXUS65 KTFX 190945
AFDTFX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
345 AM MDT SAT MAY 19 2012
.DISCUSSION...
TODAY THROUGH MONDAY...MODELS ARE IN AGREEMENT IN FORECASTING A
WEAK WEATHER DISTURBANCE ALOFT TO MOVE SOUTHEAST THROUGH THE
FORECAST AREA LATER THIS AFTERNOON THROUGH THIS EVENING. ALTHOUGH
THERE IS NOT MUCH LIFT WITH THE DISTURBANCE..WEAK INSTABILITY AND
TERRAIN EFFECTS COULD GENERATE A FEW SHOWERS MAINLY OVER THE
MOUNTAINS. LATE TONIGHT INTO EARLY MONDAY THE AREA WILL BE UNDER
THE INFLUENCE OF BUILDING HIGH PRESSURE ALOFT WHICH WILL KEEP THE
FORECAST AREA DRY. THE EXCEPTION TO THIS COULD BE IN THE NORTHWEST
WHERE INCREASING MOISTURE COULD LEAD TO THREAT OF SHOWERS SUNDAY
NIGHT. SOME GUIDANCE SUGGESTS THE THREAT OF SHOWERS WILL HOLD OFF
UNTIL MONDAY. BY LATE MONDAY THE FORECAST AREA WILL BE SOUTHWEST
FLOW ALOFT WITH INCREASED MOISTURE AND LIKELY WEAK INSTABILITY.
SHOULD SEE AT LEAST SCATTERED SHOWERS/THUNDERSTORMS OVER THE
WESTERN MOUNTAINS AND COULD POSSIBLY SEE A FEW SHOWERS FARTHER
EAST. PREVIOUS FORECAST OF WARMING TEMPERATURES TODAY THROUGH MONDAY
LOOKS GOOD WITH THE FORECAST OF A BUILDING RIDGE. BLANK
MONDAY NIGHT THROUGH SATURDAY...A BROAD UPPER-LEVEL TROUGH OF LOW
PRESSURE AND ASSOCIATED SURFACE COLD FRONT WILL MOVE INTO THE
PACIFIC NORTHWEST MONDAY NIGHT. SOUTHWEST FLOW AND AMPLE PACIFIC
MOISTURE AHEAD OF THIS TROUGH WILL BRING INCREASING PRECIPITATION
CHANCES TO THE FORECAST AREA MONDAY NIGHT AND TUESDAY. THE COLD
FRONT IS EXPECTED TO MOVE THROUGH THE STATE ON TUESDAY WITH
WIDESPREAD PRECIPITATION AND COOLING TEMPERATURES EXPECTED. MODELS
ARE INDICATING THAT THIS BROAD TROUGH WILL REMAIN OVER THE WESTERN
U.S. THROUGH THE REMAINDER OF THE WEEK AND POSSIBLY INTO NEXT
WEEKEND YIELDING UNSETTLED AND COOL CONDITIONS OVER THE NORTHERN
ROCKIES. SEVERAL SHORTWAVES WILL PROPAGATE THROUGH THE
TROUGH...HOWEVER CONFIDENCE IS LOW REGARDING THE TIMING OF EACH OF
THESE WAVES AS WELL AS PRECIPITATION AMOUNTS. ON THURSDAY...THE GFS
BRINGS A CLOSED AREA OF LOW PRESSURE OVER MONTANA WHILE THE ECMWF
KEEPS A CLOSED LOW ALONG THE WEST COAST. BOTH SOLUTIONS SUGGEST
PRECIPITATION OVER THE FORECAST AREA...HOWEVER EACH SOLUTION DIFFERS
ON WHICH AREAS CAN EXPECT THE MOST PRECIPITATION. SO FOR NOW HAVE
KEPT CHANCE POPS IN THE PLAINS WITH LIKELY POPS IN THE MOUNTAINS FOR
THE MIDDLE PART OF NEXT WEEK AND THEN CHANCE POPS OVER THE ENTIRE
AREA FOR THE LATTER HALF OF THE FORECAST PERIOD GIVEN THE
UNCERTAINTY. IN ADDITION...TEMPERATURES COULD BE AROUND 10 DEGREES
BELOW SEASONAL AVERAGES WITH SNOW LEVELS LOWERING TO NEAR 6000 FEET
BY THURSDAY. OVERALL...EACH MODEL SOLUTION INDICATES THAT A WETTER
AND COOLER PATTERN IS EXPECTED FOR MOST OF NEXT WEEK AND POTENTIALLY
INTO THE MEMORIAL DAY HOLIDAY WEEKEND. MLV
&&
.AVIATION...
UPDATED 0500Z.
WEAK HIGH PRESSURE CONTINUES TO BUILD INTO THE REGION THIS EVENING
WITH MAINLY CLEAR AND DRY CONDITIONS THROUGH TONIGHT. SLIGHT CHANCE
FOR FOG DEVELOPMENT EXISTS NEAR THE KLWT TERMINAL WHILE A DRIER
AIRMASS IS IN PLACE ELSEWHERE. GENERALLY LIGHT WINDS CONTINUE ON
SATURDAY WITH CLOUDS INCREASING THROUGH THE DAY AS A WEAK UPPER
LEVEL DISTURBANCE MOVES INTO THE REGION FROM THE WEST. A FEW SHOWERS
MAY DEVELOP SATURDAY AFTERNOON AND EVENING...MAINLY OVER THE HIGHER
TERRAIN OF CENTRAL AND SW MT. HOENISCH
&&
.PRELIMINARY POINT TEMPS/POPS...
GTF 66 40 74 50 / 10 10 10 0
CTB 62 35 72 46 / 10 10 10 20
HLN 66 39 75 48 / 10 10 10 0
BZN 64 35 73 42 / 10 10 10 0
WEY 55 28 63 33 / 20 20 0 0
DLN 63 37 72 44 / 10 10 10 0
HVR 66 38 74 48 / 0 0 0 10
LWT 60 36 70 46 / 10 10 10 0
&&
.TFX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...BLANK
LONG TERM...MLS
AVIATION...BLANK
WEATHER.GOV/GREATFALLS
000
FXUS65 KMSO 190944
AFDMSO
Area Forecast Discussion
National Weather Service Missoula MT
344 AM MDT Sat May 19 2012
.DISCUSSION...Dry westerly flow aloft will lead to a warming trend
over the weekend and into Monday, with temperatures returning to
above normal once again. Skies will gradually clear out Saturday
into Sunday, making for another cool morning Sunday. For those
hoping to catch the eclipse Sunday evening, cloud cover will begin
to increase over the region ahead of the next weather system.
Currently clouds are expected to be mainly high clouds which may
still allow a partial view of the eclipse, especially for
locations generally south of Missoula.
Confidence is high for a pattern change beginning Monday evening
as an upper level trough of low pressure and associated cold front
approaches the Northern Rockies. An impressive amount of moisture and upper
level dynamics will accompany the initial push of this system,
which will lead to widespread precipitation through Tuesday morning.
Confidence is high that most all locations will see precipitation,
although the heaviest amounts are currently expected to fall in
north central Idaho. Thunderstorms will be possible along the
front Monday evening. Periods of heavy rain will be possible. In
addition, winds will become gusty along the front Monday evening,
especially across southwest Montana and in Lemhi County.
Tuesday through Friday...The atmosphere becomes increasingly
unstable from north to south on Tuesday. Thunderstorms become likely
along and south of a line from central Idaho to Butte. Lingering
showers can be expected behind the exiting trough through
Wednesday for the entire area. As quickly as this system exits the
next low pressure system moves onto the west coast by early
Thursday. Models differ on the timing and placement of this low,
but it will keep the Northern Rockies in a moist weather pattern
through Friday. Snow levels will fall to pass level by early
Thursday but warm road surface temperatures will keep any snowfall
from sticking.
&&
.AVIATION...Mid and high level cloud cover will be present through
the day today, which may locally obscure the higher terrain.
Clouds are expected to gradually decrease this afternoon and
evening leading to clear skies. A few localized showers will be
possible, mainly across northwest Montana, but will cause few
impacts to local airfields. High pressure will build over the
region leading to generally pleasant flying conditions.
&&
.MSO WATCHES/WARNINGS/ADVISORIES...
MT...None.
ID...None.
&&
$$
jp/ml
000
FXUS65 KGGW 190919
AFDGGW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GLASGOW MT
319 AM MDT SAT MAY 19 2012
.SHORT TERM...FOR NORTHEAST MONTANA...TODAY THROUGH MONDAY...
THE UPPER LEVEL LOW IN CENTRAL ALBERTA AND SASKATCHEWAN THAT
DROVE THE SHORTWAVE DISTURBANCE THROUGH THE REGION ON FRIDAY WILL
DRIVE ANOTHER MUCH WEAKER SHORTWAVE DISTURBANCE THROUGH MONTANA
TODAY AND TONIGHT. THE MAIN AFFECT OF THIS DISTURBANCE WILL BE TO
NUDGE A COLD BOUNDARY SOUTH AGAINST NORTHEAST MONTANA. THIS WILL
MAINTAIN A COOLING AFFECT SO THAT TEMPERATURES WILL TREND NEAR OR
JUST BELOW NORMAL TODAY. EXCEPT FOR A FEW LINGERING RADAR ECHOES
ALL SHOWER ACTIVITY HAS MOVED TO THE EAST THIS MORNING. HOWEVER
THE SHORTWAVE SHOULD PRODUCE SOME MID-LEVEL CLOUDS. HIGH SURFACE
PRESSURE SHOULD QUIET DOWN THE WINDS.
THE REMAINDER OF THE SHORT TERM WILL SEE AN UPPER RIDGE AXIS MOVE
FROM THE WEST COAST TO MONTANA THROUGH MONDAY FOR CONTINUING DRY
CONDITIONS. DURING THAT PERIOD THICKNESS HEIGHTS WILL RISE FROM
AROUND 550DM TO 570DM. TEMPERATURES WILL TREND TO AROUND 15F TO
20F ABOVE NORMAL BY MONDAY AFTERNOON. SUNDAY NIGHT A WEST COAST
TROUGH WILL BE EJECTING MOISTURE IN THE DIRECTION OF THE NORTHERN
ROCKIES. WITH A DEVELOPING LEE SURFACE TROUGH EXPECT SKY COVER TO
BEGIN TO INCREASE FOR SUNDAY EVENING AND MONDAY.
THE POSSIBILITY OF INCREASING CLOUD COVER EARLY SUNDAY EVENING
COULD INTERFERE WITH VIEWING THE PARTIAL SOLAR ECLIPSE WHEN THE
MOON MOVES IN FRONT OF THE SUN. BUT THERE ARE CURRENTLY DIFFERENCES
IN TIMING AMONG THE MODELS...SO SHOULD GET A BETTER IDEA OF CLOUD
COVER THE CLOSER TO THE SOLAR EVENT WE GET WITH LATER MODEL RUNS.
SCT
.LONG TERM...MONDAY NIGHT THROUGH SATURDAY...
UPPER RIDGE MOVES TO THE EAST MONDAY NIGHT AND SOUTHWEST FLOW
ALOFT WILL PREVAIL AHEAD OF AN UPPER LOW THAT MOVES INTO THE AREA
BY WEDNESDAY. THERE WILL BE A COLD FRONT MOVING THROUGH EASTERN
MONTANA DURING THE DAY ON TUESDAY. AIRMASS ALONG AND AHEAD OF THE
FRONT SHOULD BE UNSTABLE ENOUGH TO SUPPORT SOME THUNDERSTORMS.
MODELS HAVE VARIED ON WHERE THE BEST INSTABILITY WILL BE. WILL
MENTION A CHANCE OF THUNDERSTORMS.
THE GFS AND ECMWF PLACE THE UPPER LOW DIFFERENTLY ON WEDNESDAY AND
WEDNESDAY NIGHT WITH GFS FAVORING MONTANA AND ECMWF PUTTING THE
LOW IN SASKATCHEWAN. BOTH MODELS HAVE EASTERN MONTANA IN A DRY
SLOT FOR AT LEAST PART OF THE DAY. HOWEVER...THAT WILL ALLOW FOR
DAYTIME HEATING TO DESTABILIZE THE ATMOSPHERE. MAY SEE SOME
SHOWERS AND THUNDERSTORMS DEVELOP AS A RESULT. WILL MENTION A
CHANCE FOR NOW.
THE MODEL DIFFERENCES CONTINUE THURSDAY WITH THE ECMWF KEEPING THE
UPPER LOW IN SASKATCHEWAN AND DRY SLOT OVER EASTERN MONTANA WHILE
THE GFS TRACKS ITS UPPER LOW INTO NORTH DAKOTA AND MANITOBA. WILL
MAINTAIN A CHANCE OF SHOWERS GIVEN THE UNCERTAINTY.
FRIDAY AND SATURDAY...THE NEXT UPPER LOW DIGS SOUTH INTO NORTHERN
CALIFORNIA WITH RIDGE TO THE EAST. MONTANA WILL BE IN A SOMEWHAT
MOIST SOUTHWEST FLOW ALOFT. WILL MAINTAIN A CHANCE OF SHOWERS FOR
NOW. FORRESTER
&&
.AVIATION...
A FEW LOW CLOUDS WITH CEILINGS AS LOW AS 4000 FEET WILL MOVE
THROUGH NORTHEAST MONTANA EARLY THIS MORNING. OTHERWISE...LOOK FOR
MOSTLY CLEAR SKIES TODAY AND TONIGHT AS HIGH PRESSURE SYSTEM
BUILDS INTO THE AREA. NORTHWEST WINDS WILL BE 10 TO 20 KNOTS TODAY
WITH HIGHER SPEEDS AT KGDV AND KSDY. WINDS WILL BECOME LIGHT AND
VARIABLE AFTER SUNSET THIS EVENING.
&&
.GLASGOW WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
WEATHER.GOV/GLASGOW
000
FXUS65 KBYZ 190907
AFDBYZ
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BILLINGS MT
307 AM MDT SAT MAY 19 2012
.SHORT TERM...VALID FOR TDY...SUN AND MON...
ENERGETIC TROF IN THE CENTRAL ROCKIES AND HIGH PLAINS CONTINUES
TO SPREAD SOME SHOWERS INTO OUR FAR EAST...WITH PCPN GENERALLY
SCATTERED AND EAST OF A SHERIDAN TO MILES CITY LINE AS OF 08Z.
WE WILL CONTINUE TO DRY OUT FROM THE NW AS THE EARLY MORNING WEARS
ON. TEMPS HAVE ALREADY FALLEN INTO THE 30S ALONG AND NORTHWEST OF
A ROUNDUP TO LIVINGSTON LINE...AND A FROST OR FREEZE CAN BE
EXPECTED IN THESE AREAS THIS MORNING. PER THE LIGHT GRADIENT AND
LOW DEW POINT DEPRESSIONS THINK SOME FOG IS STILL POSSIBLE EARLY
THIS MORNING. RECENT 11-3.9 SAT IMAGERY SHOWED SOME UPSLOPE FOG OR
STRATUS NEAR THE CRAZY MOUNTAINS AND ALSO JUST NORTH OF PARK
CITY...AND COULD SEE SOME EXPANSION OF THIS OVER THE NEXT FEW
HOURS.
WEAK PACIFIC SHORTWAVE MOVING THROUGH WA NOW WILL GENERATE SOME
MODEST ASCENT IN OUR WESTERN PARTS BY THIS AFTN. THOUGH OUR
AIRMASS IS CURRENTLY DRYING CONSIDERABLY SINCE YESTERDAY...THIS
NEXT PIECE OF ENERGY WILL BRING INCREASED MID LEVEL MOISTURE WHICH
ALONG WITH MODEST DIURNAL INSTABILITY AND WEAK UPSLOPE FLOW SHOULD
HELP TO GENERATE A FEW SHOWERS OVER OUR WESTERN MTNS AND FOOTHILLS
LATER TODAY. COULD SEE A LIGHT SHOWER OR SPRINKLE REACH AS FAR
EAST AS BILLINGS THIS EVENING...OTHERWISE BETTER CHANCES WILL BE
TO OUR WEST AND SOUTH. MOST OF THE AREA WILL BE DRY UNDER
INFLUENCE OF STABLE SFC RIDGING ACROSS OUR EASTERN PLAINS.
AFTER A REASONABLY COOL DAY TODAY WITH HIGHS ABOUT 3 TO 5 DEGREES
BELOW NORMAL...RIDGE WILL BUILD IN FOR DRY/WARMER CONDITIONS
SUNDAY AND MONDAY. WILL SEE 70S ON SUNDAY AND 80S ON MONDAY...AND
IN FACT MID TO UPPER 80S ON THE LATTER PER 700MB TEMPS TO 8-10C
AND GOOD MIXING. THOUGH BOUNDARY LAYER MOISTURE WILL BE LACKING
HEIGHTS WILL BEGIN TO FALL AND WE SHOULD SEE ENOUGH DIURNAL
INSTABILITY FOR SOME WESTERN MTNS WEAK CONVECTION MONDAY AFTN/
EVENING...THOUGH FORCING FROM PACIFIC TROF LOOKS TO LAG THIS
ACTIVITY. CHANCE OF SHOWERS SHOULD INCREASE IN OUR FAR WEST
THROUGH MONDAY NIGHT AS PACIFIC FLOW MOISTENS AND COLD FRONT
APPROACHES.
FOR THOSE INTERESTED IN THE SOLAR ECLIPSE SUNDAY EVENING...THOUGH
IT WILL BE DRY IT LOOKS AS IF WE MAY HAVE BROKEN MID/HIGH CLOUD
AROUND THE AREA.
JKL
.LONG TERM...VALID FOR TUE...WED...THU...FRI...
MODEL AGREEMENT IS RELATIVELY GOOD THROUGH THE PERIOD WITH BROAD
TROUGH MOVING INTO PACIFIC NORTHWEST TUESDAY DRIVING A PACIFIC
COLD FRONT ACROSS THE AREA TUESDAY NIGHT INTO EARLY WEDNESDAY.
UPPER TROUGH DEEPENS OVER THE NORTHERN ROCKIES WEDNESDAY THROUGH
THURSDAY...LEAVING THE AREA COOL AND UNSETTLED. MEANWHILE...MODELS
AGREE VERY WELL ON A CUTOFF LOW SETTLING OVER CALIFORNIA BY FRIDAY
NIGHT...PLACING THE NORTHERN ROCKIES UNDER SOUTHWEST FLOW ALOFT
AND INCREASINGLY DIFLUENT FLOW. THIS OPENS THE DOOR FOR
POTENTIALLY WET MEMORIAL DAY WEEKEND AS ALL MODELS SUGGEST
EJECTING SHORTWAVE TROUGHS NORTHEASTWARD TOWARD NORTHERN ROCKIES.
THIS WILL BEAR WATCHING...BUT MODEL AGREEMENT WITH THIS FEATURE IS
PARTICULARLY NOTEWORTHY CONSIDERING THE FORECAST RANGE AND THE
GENERAL PREDICTABILITY CHALLENGES DURING THIS TIME OF YEAR AT
THOSE RANGES.
SPECIFICALLY...BEGAN TO NUDGE PRECIPITATION CHANCES UPWARD A BIT
BEGINNING TUESDAY NIGHT AND RUNNING THROUGH THE REST OF THE
PERIOD. BEST THREATS FOR PRECIPITATION ACROSS THE AREA CERTAINLY
APPEAR TO BE WEDNESDAY AND THURSDAY. ALSO TRENDED HIGH
TEMPERATURES 5 TO 7 DEGREES COOLER WEDNESDAY THROUGH FRIDAY IN
RESPONSE TO GOOD MODEL AGREEMENT ON THIS COOLING TREND. MEIER
&&
.AVIATION...
SOME FOG CAN BE EXPECTED EARLY THIS MORNING DUE TO COMBINATION OF
LOW LEVEL MOISTURE FROM YESTERDAYS RAINFALL...LIGHT WINDS AND
CLEARING SKIES. OTHERWISE...VFR CONDITIONS WILL PREVAIL ACROSS THE
AREA TODAY AND TONIGHT...WITH GENERALLY VERY LIGHT WIND. MID LEVEL
CLOUDS WILL LINGER ACROSS PORTIONS SOUTHEAST MONTANA AND NORTHER
WYOMING THROUGH MID DAY BEFORE CLEARING BY LATE AFTERNOON. MEIER
&&
.PRELIMINARY POINT TEMP/POPS...
TDY SUN MON TUE WED THU FRI
-------------------------------------------------------
BIL 064 043/076 052/087 058/076 047/060 044/060 044/061
1/B 20/B 00/B 13/T 44/T 34/W 33/W
LVM 060 035/074 043/084 049/070 039/056 037/056 038/056
2/W 20/B 00/B 35/T 44/T 33/W 44/W
HDN 065 039/077 048/089 053/079 044/061 043/061 040/062
1/U 20/B 00/B 13/T 44/T 33/W 33/W
MLS 066 041/076 052/089 058/083 048/065 046/062 042/064
0/U 00/U 00/B 13/T 44/T 34/W 33/W
4BQ 064 039/074 049/087 053/084 045/063 043/062 041/063
1/B 10/B 00/U 03/T 44/T 34/W 33/W
BHK 064 038/071 046/084 054/083 050/063 044/060 041/061
0/N 00/U 00/B 03/T 44/T 34/W 33/W
SHR 060 037/073 044/085 050/079 041/059 039/059 037/060
1/B 20/B 00/U 03/T 54/T 44/W 33/W
&&
.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...NONE.
WY...NONE.
&&
$$
WEATHER.GOV/BILLINGS
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