000
FXUS65 KBYZ 230240
AFDBYZ
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BILLINGS MT
840 PM MDT WED MAY 22 2013
.UPDATE...
NOT TOO MUCH TO UPDATE TONIGHT. WEATHER PATTERN IS UNFOLDING MORE
OR LESS AS ANTICIPATED...SO FORECAST LOOKS TO BE IN PRETTY GOOD
SHAPE. DID RAISE POPS TO LIKELIES OVER THE EASTERN BEARTOOTHS AND
RAISED POPS CLOSER TO LIKELIES OVER THE BEARTOOTH FOOTHILLS AS
SOME SHOWER AND THUNDERSTORM ACTIVITY CONTINUES TO MOVE
NORTHEASTWARD INTO THAT AREA AS NOTED ON RADAR. JUST MADE SOME
MINOR ADJUSTMENTS TO WINDS THIS EVENING AND TEMPS OVERNIGHT. STC
&&
.SHORT TERM...VALID FOR THU AND FRI...
LARGE UPPER LEVEL LOW WILL BE STATIONARY OVER THE PACIFIC
NORTHWEST STATES THIS AFTERNOON THROUGH THURSDAY NIGHT. THIS WILL
PROVIDE A SOUTHERLY AND DIVERGENT FLOW ALOFT TO OUR FORECAST AREA
THROUGH THURSDAY. SEVERAL DISTURBANCES WILL ROTATE THEIR WAY
AROUND THE LOW AND EJECT ACROSS MAINLY THE WESTERN HALF OF OUR
FORECAST AREA. BEST UPPER LEVEL DYNAMICS WILL BE WEST OF BILLINGS
THROUGH TONIGHT BEFORE SLOWLY SHIFTING EAST THURSDAY INTO THURSDAY
NIGHT. WILL CONTINUE WITH CHANCE TO LIKELY POPS FROM BILLINGS WEST
FROM LATE THIS AFTERNOON THROUGH THURSDAY.
SOUNDINGS SHOW A CAP ACROSS THE ENTIRE AREA THIS AFTERNOON DUE IN
PART BY AN EASTERLY SURFACE WIND WHICH HAS ALLOWED A LOW STRATUS
DECK TO REMAIN IN PLACE ACROSS OUR CENTRAL AND EASTERN LOCATIONS
KEEPING TEMPERATURES ON THE COOL SIDE. LIVINGSTON HAS REMAINED IN
THE 40S ALL DAY EXCEPT THE PAST HOUR WHEN THEY BROKE 50 DEGREES.
GIVEN THE RAINFALL THIS PAST WEEKEND...DEWPOINTS ARE SURPRISINGLY
A BIT LOW AND ONLY IN THE UPPER 30S TO LOWER 40S. SOUNDINGS DO
SHOW THE CAP OVER THE LIVINGSTON AREA WEAKENING THIS EVENING SO
CAN`T RULE OUT AN ISOLATED SEVERE THUNDERSTORM WEST OF BILLINGS AS
SHEAR REMAINS QUITE GOOD. HOWEVER...CAPE IS QUITE LIMITED AND
MAINLY OVER THE BEARTOOTH/ABSAROKA MOUNTAINS AND THERE IS ALSO NOT
MUCH OF ANY DISTURBANCE MOVING OVERHEAD TO TRIGGER TOO MUCH AT
THIS TIME.
SAME PATTERN HOLDS THURSDAY WITH THE FOCUS SHIFTING SLIGHTLY
FURTHER EAST TOWARD BILLINGS AS THE UPPER LEVEL DIVERGENCE AND
WIND SHEAR SHIFT INTO THE CENTRAL AND EASTERN ZONES. HOWEVER...A
VERY STRONG LOW LEVEL JET WILL BE IN PLACE RESULTING IN SUSTAINED
WINDS IN THE 20 TO 35 MPH RANGE WITH GUSTS NEAR 50 MPH FOR FALLON
AND CARTER COUNTIES. SOUNDINGS SHOW A VERY STRONG CAP ACROSS OUR
EASTERN AREAS THROUGH THE DAY THURSDAY AND INTO THURSDAY NIGHT. AT
THIS TIME...GIVEN UPPER LOW PLACEMENT WELL WEST OF THE AREA...NO
STRONG DISTURBANCE LOOKS TO MOVE ACROSS THE EAST TO HELP ERODE THE
CAP SO THUNDERSTORM ACTIVITY LOOKS LIMITED.
UPPER LOW BEGINS TO SHIFT NORTH INTO CANADA FRIDAY. MODELS SHOW
QUITE A BIT OF DRYING AT MID AND LOWER LEVELS SO HAVE LOWERED POPS
QUITE A BIT TO JUST A SLIGHT CHANCE FOR THE DAY FRIDAY AND INTO
FRIDAY NIGHT. HOOLEY
.LONG TERM...VALID FOR SAT...SUN...MON...TUE...WED...
UNSETTLED SW FLOW WILL BE OVER THE FORECAST AREA THROUGH THE
EXTENDED PERIOD AS SEVERAL UPPER LOWS MOVE THROUGH THE PACIFIC
NW. THE AIRMASS WILL BE MOIST...AS PACIFIC MOISTURE AND GULF
MOISTURE MERGE OVER THE REGION. IN ADDITION...THERE WILL BE
PERIODS OF STRONG INSTABILITY BASED ON MODEL LIFTED INDICES AND
BUFKIT SOUNDINGS. THE STRONGEST INSTABILITY WILL BE OVER AREAS E
OF KBIL THROUGH MON. A FAIR AMOUNT OF SHEAR WILL ACCOMPANY THE
INSTABILITY...SO THE POSSIBILITY EXISTS FOR SEVERE THUNDERSTORMS.
RAINFALL COULD BE HEAVY AT TIMES OVER CENTRAL AND EASTERN AREAS BASED
ON HIGH PRECIPITABLE WATERS ON THE GFS. OTHERWISE...THERE WAS A
MODERATE TO HIGH AMOUNT OF MODEL SPREAD IN TERMS OF POPS...AS THE
GFS AND ECWMF VARIED IN HOW THEY HANDLED THE ENERGY IN THE SW
FLOW. INHERITED FORECAST OF SCATTERED POPS THROUGH MOST OF THE
PERIOD HANDLED THE SITUATION WELL AND HAVE MADE ONLY A FEW
ADJUSTMENTS BASED ON NEW MODEL DATA. TEMPERATURES IN THE UPPER 70S
TO LOWER 80S WERE ALSO ON TRACK GIVEN FORECAST 700 MB MIXDOWN
TEMPERATURES. ARTHUR
&&
.AVIATION...
SCATTERED SHOWERS AND AN ISOLATED THUNDERSTORM IS POSSIBLE WEST OF
KBIL THROUGH THE NIGHT. LOW CLOUDS WILL CONTINUE AT KBIL...KLVM AND
KSHR BUT DRIER AIR SHOULD KEEP LOW CLOUDS FROM RETURNING TO KMLS.
EXPECT SHOWERS AND THUNDERSTORMS TO DEVELOP THURSDAY AFTERNOON AND
PROGRESS TO A KSHR-KBIL LINE BY EVENING. BORSUM
&&
.PRELIMINARY POINT TEMP/POPS...
THU FRI SAT SUN MON TUE WED
-----------------------------------------------------------
BIL 049/073 050/075 049/077 053/080 053/077 051/078 053/077
44/T 42/T 12/T 33/T 33/T 33/T 33/T
LVM 045/065 041/070 039/078 041/080 042/078 041/076 043/075
66/T 62/T 22/T 23/T 33/T 33/T 33/T
HDN 048/077 050/078 047/079 053/082 052/080 051/080 054/080
32/T 22/T 12/T 33/T 33/T 33/T 33/T
MLS 049/072 051/078 052/079 057/083 058/079 054/080 058/080
11/N 22/T 23/T 33/T 44/T 33/T 33/T
4BQ 046/074 052/079 049/081 055/085 052/081 052/082 054/081
11/N 12/T 12/T 33/T 33/T 33/T 33/T
BHK 044/066 047/075 050/073 056/077 056/077 052/077 057/077
11/N 12/T 24/T 43/T 33/T 33/T 33/T
SHR 045/074 046/075 045/079 048/083 048/079 046/077 051/078
22/T 22/T 12/T 22/T 23/T 33/T 33/T
&&
.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...NONE.
WY...NONE.
&&
$$
WEATHER.GOV/BILLINGS
000
FXUS65 KBYZ 222047
AFDBYZ
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BILLINGS MT
247 PM MDT WED MAY 22 2013
.SHORT TERM...VALID FOR THU AND FRI...
LARGE UPPER LEVEL LOW WILL BE STATIONARY OVER THE PACIFIC
NORTHWEST STATES THIS AFTERNOON THROUGH THURSDAY NIGHT. THIS WILL
PROVIDE A SOUTHERLY AND DIVERGENT FLOW ALOFT TO OUR FORECAST AREA
THROUGH THURSDAY. SEVERAL DISTURBANCES WILL ROTATE THEIR WAY
AROUND THE LOW AND EJECT ACROSS MAINLY THE WESTERN HALF OF OUR
FORECAST AREA. BEST UPPER LEVEL DYNAMICS WILL BE WEST OF BILLINGS
THROUGH TONIGHT BEFORE SLOWLY SHIFTING EAST THURSDAY INTO THURSDAY
NIGHT. WILL CONTINUE WITH CHANCE TO LIKELY POPS FROM BILLINGS WEST
FROM LATE THIS AFTERNOON THROUGH THURSDAY.
SOUNDINGS SHOW A CAP ACROSS THE ENTIRE AREA THIS AFTERNOON DUE IN
PART BY AN EASTERLY SURFACE WIND WHICH HAS ALLOWED A LOW STRATUS
DECK TO REMAIN IN PLACE ACROSS OUR CENTRAL AND WESTERN LOCATIONS
KEEPING TEMPERATURES ON THE COOL SIDE. LIVINGSTON HAS REMAINED IN
THE 40S ALL DAY EXCEPT THE PAST HOUR WHEN THEY BROKE 50 DEGREES.
DEWPOINTS ARE A BIT LOW AND ONLY IN THE UPPER 30S TO LOWER 40S.
SOUNDINGS DO SHOW THE CAP OVER THE LIVINGSTON AREA WEAKENING THIS
EVENING SO CAN`T RULE OUT AN ISOLATED SEVERE THUNDERSTORM WEST OF
BILLINGS AS SHEAR REMAINS QUITE GOOD. HOWEVER...CAPE IS QUITE
LIMITED AND MAINLY OVER THE BEARTOOTH/ABSAROKA MOUNTAINS AND THERE
IS ALSO NOT MUCH OF ANY DISTURBANCE MOVING OVERHEAD TO TRIGGER TOO
MUCH AT THIS TIME.
SAME PATTERN HOLDS THURSDAY WITH THE FOCUS SHIFTING SLIGHTLY
FURTHER EAST TOWARD BILLINGS AS THE UPPER LEVEL DIVERGENCE AND
WIND SHEAR SHIFT INTO THE CENTRAL AND EASTERN ZONES. HOWEVER...A
VERY STRONG LOW LEVEL JET WILL BE IN PLACE RESULTING IN SUSTAINED
WINDS IN THE 20 TO 35 MPH RANGE WITH GUSTS NEAR 50 MPH FOR FALLON
AND CARTER COUNTIES. SOUNDINGS SHOW A VERY STRONG CAP ACROSS OUR
EASTERN AREAS THROUGH THE DAY THURSDAY AND INTO THURSDAY NIGHT. AT
THIS TIME...GIVEN UPPER LOW PLACEMENT WELL WEST OF THE AREA...NO
STRONG DISTURBANCE LOOKS TO MOVE ACROSS THE EAST TO HELP ERODE THE
CAP SO THUNDERSTORM ACTIVITY LOOKS LIMITED.
UPPER LOW BEGINS TO SHIFT NORTH INTO CANADA FRIDAY. MODELS SHOW
QUITE A BIT OF DRYING AT MID AND LOWER LEVELS SO HAVE LOWERED POPS
QUITE A BIT TO JUST A SLIGHT CHANCE FOR THE DAY FRIDAY AND INTO
FRIDAY NIGHT. HOOLEY
.LONG TERM...VALID FOR SAT...SUN...MON...TUE...WED...
UNSETTLED SW FLOW WILL BE OVER THE FORECAST AREA THROUGH THE
EXTENDED PERIOD AS SEVERAL UPPER LOWS MOVE THROUGH THE PACIFIC
NW. THE AIRMASS WILL BE MOIST...AS PACIFIC MOISTURE AND GULF
MOISTURE MERGE OVER THE REGION. IN ADDITION...THERE WILL BE
PERIODS OF STRONG INSTABILITY BASED ON MODEL LIFTED INDICES AND
BUFKIT SOUNDINGS. THE STRONGEST INSTABILITY WILL BE OVER AREAS E
OF KBIL THROUGH MON. A FAIR AMOUNT OF SHEAR WILL ACCOMPANY THE
INSTABILITY...SO THE POSSIBILITY EXISTS FOR SEVERE THUNDERSTORMS.
RAINFALL COULD BE HEAVY AT TIMES OVER CENTRAL AND EASTERN AREAS BASED
ON HIGH PRECIPITABLE WATERS ON THE GFS. OTHERWISE...THERE WAS A
MODERATE TO HIGH AMOUNT OF MODEL SPREAD IN TERMS OF POPS...AS THE
GFS AND ECWMF VARIED IN HOW THEY HANDLED THE ENERGY IN THE SW
FLOW. INHERITED FORECAST OF SCATTERED POPS THROUGH MOST OF THE
PERIOD HANDLED THE SITUATION WELL AND HAVE MADE ONLY A FEW
ADJUSTMENTS BASED ON NEW MODEL DATA. TEMPERATURES IN THE UPPER 70S
TO LOWER 80S WERE ALSO ON TRACK GIVEN FORECAST 700 MB MIXDOWN
TEMPERATURES. ARTHUR
&&
.AVIATION...
SHOWERS AND THUNDERSTORMS WILL INCREASE OVER AREAS W OF KMLS
THROUGH THIS EVENING. THE BEST CHANCES FOR PRECIPITATION WILL BE
FROM HARLOWTON TO RED LODGE W. ISOLATED TO SCATTERED SHOWERS WILL
OCCUR W OF KMLS OVERNIGHT AND THU MORNING. THUNDERSTORMS WILL
REDEVELOP OVER THE SAME AREAS THU AFTERNOON. EXPECT VFR TO MVFR
CONDITIONS. IFR TO LIFR WILL BE POSSIBLE IN SOME OF THE STRONGER
STORMS. SURFACE WINDS WILL BE E AT 15 TO 25 KT ACROSS THE AREA
THROUGH TONIGHT. ON THU...WINDS WILL INCREASE FROM THE SE OVER
AREAS E OF KBIL TO 25 TO 35 KT. LOW-LEVEL WIND SHEAR WILL BE
POSSIBLE LATE TONIGHT AND EARLY THU OVER KMLS. ARTHUR
&&
.PRELIMINARY POINT TEMP/POPS...
THU FRI SAT SUN MON TUE WED
-----------------------------------------------------------
BIL 049/073 050/075 049/077 053/080 053/077 051/078 053/077
34/T 42/T 12/T 33/T 33/T 33/T 33/T
LVM 045/065 041/070 039/078 041/080 042/078 041/076 043/075
66/T 62/T 22/T 23/T 33/T 33/T 33/T
HDN 048/077 050/078 047/079 053/082 052/080 051/080 054/080
22/T 22/T 12/T 33/T 33/T 33/T 33/T
MLS 049/072 051/078 052/079 057/083 058/079 054/080 058/080
11/N 22/T 23/T 33/T 44/T 33/T 33/T
4BQ 046/074 052/079 049/081 055/085 052/081 052/082 054/081
11/N 12/T 12/T 33/T 33/T 33/T 33/T
BHK 044/066 047/075 050/073 056/077 056/077 052/077 057/077
11/N 12/T 24/T 43/T 33/T 33/T 33/T
SHR 045/074 046/075 045/079 048/083 048/079 046/077 051/078
22/T 22/T 12/T 22/T 23/T 33/T 33/T
&&
.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...NONE.
WY...NONE.
&&
$$
WEATHER.GOV/BILLINGS
000
FXUS65 KBYZ 221520
AFDBYZ
AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE BILLINGS MT
920 AM MDT WED MAY 22 2013
.UPDATE...
CURRENT FORECAST IS IN GOOD SHAPE AND HAVE ONLY MADE A MINOR
ADJUSTMENT TO SKY COVER WITH THIS UPDATE. SATELLITE SHOWING CLOUDS
ERODING QUICKLY ACROSS THE EAST FROM ROSEBUD COUNTY EAST AND
SOUTHEAST. HAVE REDUCED MORNING AND EARLY AFTERNOON CLOUDS TO
REFLECT MORE OF A PARTLY SUNNY DAY FOR THESE AREAS.
ELSEWHERE...COOL EASTERLY UPSLOPE FLOW HAS RESULTED IN THE
DEVELOPMENT OF A STRATUS DECK FOR THE CENTRAL AND WESTERN AREAS.
HAVE INCREASED CLOUD COVER FOR THE CENTRAL AREAS TO REMOVE THE
MOSTLY SUNNY WORDING. HOOLEY
&&
.SHORT TERM...VALID FOR TDY AND THU...
THE DEEP UPPER LOW OVER SOUTHWEST MINNESOTA WILL FINALLY LOSE ITS
GRIP ON THE EAST TODAY. LOW CLOUDS STILL PRESENT OVER THE EAST
THIS MORNING WITH EVEN SOME LIGHT SHOWERS OR SPRINKLES MOVING WEST
FROM NORTH DAKOTA INTO FALLON AND CARTER COUNTIES. WILL HAVE LOW
POPS IN THESE TWO COUNTIES THIS MORNING. RIDGING SHOULD MOVE INTO
THE EAST LATE THIS MORNING AND CLEAR THE CLOUD COVER OUT. THE
FOCUS THEN TURNS TO THE OTHER DEEP LOW OVER NORTH AMERICA...OVER
THE PACIFIC NORTHWEST.
THIS WESTERN LOW WILL EDGE SLOWLY EASTWARD TODAY AND INCREASE
UPPER DIVERGENCE OVER THE WESTERN PART OF THE FORECAST AREA. SHEAR
INCREASES OVER THE WEST...BUT CAPE SEEMS LIMITED. DEWPOINTS WERE
CURRENTLY IN THE UPPER 30S AT LIVINGSTON AND PROGGED TO ONLY RISE
INTO THE MID 40S THIS AFTERNOON. EASTERLY WINDS WILL BE PRESENT
OVER THE ENTIRE AREA TODAY AND THIS WILL PROVIDE A CAP ABOVE 750MB
INHIBITING SURFACE BASED CONVECTION. MID LEVEL CAPES WERE NOT THAT
HIGH DESPITE INCREASING SHEAR. DIVERGENCE AND MOUNTAINOUS TERRAIN
SHOULD TRIGGER CONVECTION OVER SOUTHWEST MONTANA TODAY AND LIFT
THE STORMS NORTHEAST THIS AFTERNOON. MODELS HAVE BEEN PERSISTENT
ON THAT. WILL KEEP HIGH POPS FOR THE WEST. PRECIPITABLE WATER
AMOUNTS AROUND .75 WOULD PRODUCE LOCALLY HEAVY RAINS...BUT STORM
MOTION SHOULD BE ENOUGH TO LIMIT FLOOD POTENTIAL. AS FAR AS SEVERE
POTENTIAL TODAY GOES...BELIEVE THERE IS A THREAT FOR SOME HAIL
GIVEN THE SHEAR...BUT CAP AND WEAK CAPE SHOULD KEEP MOST ACTIVITY
BELOW SEVERE LEVELS.
FOR THURSDAY...SOUTHEAST WINDS WILL INCREASE OVER THE EAST. IN
FACT...WIND GUSTS TO 50 MPH WILL BE POSSIBLE AT BAKER WITH
SUSTAINED WINDS UP TO 35 MPH AS A SURFACE LOW DEEPENS OVER THE
WEST. THESE WINDS WILL KEEP THE EAST CAPPED FROM CONVECTION.
ORDINARILY EAST TO SOUTHEAST WINDS WOULD BRING IN HIGHER DEWPOINTS
BUT THAT DOES NOT APPEAR TO THE BE THE CASE THIS TIME. DEWPOINTS
IN THE DAKOTAS WERE IN THE MID TO UPPER 40S...SO THAT LOOKS TO BE
THE LIMIT FOR THE FORECAST AREA ON THURSDAY. DEWPOINTS BELOW 50
WOULD LIMIT SEVERE POTENTIAL OVER CENTRAL AND WESTERN ZONES.
CONVECTION SHOULD TRIGGER WITH SHORTWAVES SPINNING OFF THE WESTERN
LOW AND IN AMONGST SOME SURFACE CONVERGENCE WITH THE LOW. CAPE
INCREASES OVER CENTRAL ZONES DURING THE AFTERNOON. THE CAP LOOKS
TO BE DISMISSED DURING THE AFTERNOON AS EAST WINDS DECREASE OVER
CENTRAL AND WESTERN ZONES. ABOUT 30-35KTS OF SHEAR SHOULD BE
PRESENT BUT AGAIN CAPES LOOK ON THE LOW SIDE DUE TO LOWER
DEWPOINTS. COULD BE A HAIL THREAT WITH SHEAR PRESENT. ANY SEVERE
CONVECTION SHOULD BE ISOLATED WITH THE MAIN THREAT BEING LOCALLY
HEAVY RAIN WITH...PWATS AROUND .75...AND HAIL DUE TO SHEAR. WILL
OPT TO NOT MENTION SEVERE IN THE ZONES BUT FOLKS SHOULD BE
PREPARED FOR THE POSSIBILITY OF STRONG THUNDERSTORMS BOTH TODAY
WEST AND THURSDAY OVER CENTRAL AND WEST. WILL KEEP MENTION OF
ISOLATED SEVERE IN THE HWO ALONG WITH THE STRONG SOUTHEAST WINDS
OVER FALLON AND CARTER COUNTIES THURSDAY. WARMER TEMPERATURES
EXPECTED THURSDAY AS THE CAP WEAKENS. TWH
.LONG TERM...VALID FOR FRI...SAT...SUN...MON...TUE...
A FEW MINOR CHANGES TO THE EXTENDED PERIOD...BUT OVERALL FORECAST
LOOKS LIKE IT SHOULD BE IN PRETTY GOOD SHAPE.
MODELS APPEAR IN PRETTY GOOD AGREEMENT THROUGH ABOUT
SUNDAY...WITH UPPER LEVEL LOW PRESSURE SYSTEM OVER THE PACIFIC
NORTHWEST LIFTING SLOWLY TO THE NORTHEAST. THIS WILL KEEP THE
REGION IN PERSISTENT SOUTHWEST FLOW ALOFT. EASTERLY SURFACE FLOW
DEVELOPS BY SATURDAY...WITH LLJ TAKING SHAPE IN EASTERN ZONES AND
STRENGTHENING THROUGH SUNDAY. THIS SHOULD BRING ADDED INSTABILITY
AND MOISTURE TO THE SYSTEM AS WELL. MODELS THEN FAVOR A TROF...IN
SOME SHAPE...PUSHING ACROSS THE REGION FOR MONDAY THROUGH
WEDNESDAY. THE GFS IS LEANING TOWARD A DEEPER SLOW MOVING TROF...
WHILE EC FAVORS A MORE SHALLOW...SOMEWHAT NEGATIVELY TILTED TROF
THAT KICKS THROUGH THE REGION MUCH MORE QUICKLY...BUT KEEPS
SOUTHWEST SLOW INTACT ACROSS THE REGION. HAVE KEPT CLIMO TYPE...TO
SLIGHTLY HIGHER POPS IN PLACE ACROSS THE REGION THROUGHOUT THE
BULK OF THE PERIOD.
AS FOR TEMPERATURES...EXPECT TO SEE SLIGHTLY ABOVE NORMAL TEMPS
THROUGH THE PERIOD. MODELS CAME IN WARMER THROUGH MUCH OF THE
PERIOD...SO TRENDED TEMPS UP SLIGHTLY. AAG
&&
.AVIATION...
SHOWERS AND THUNDERSTORMS WILL BE ON THE INCREASE FROM KMLS TO
KSHR W THIS AFTERNOON AND EVENING. THE BEST CHANCES FOR
PRECIPITATION WILL BE FROM HARLOWTON TO RED LODGE W. ISOLATED TO
SCATTERED SHOWERS WILL OCCUR FROM KMLS TO KSHR W OVERNIGHT AND THU
MORNING. EXPECT MAINLY MVFR TO IFR CEILINGS TODAY THROUGH THU
MORNING WITH LOWER CEILINGS AND REDUCED VISIBILITIES IN
PRECIPITATION. SURFACE WINDS WILL BE E 10 TO 20 KT THROUGH THU
MORNING. SE WINDS WILL INCREASE TO 25 TO 35 KT E OF KBIL THU
MORNING. ARTHUR
&&
.PRELIMINARY POINT TEMP/POPS...
TDY THU FRI SAT SUN MON TUE
-------------------------------------------------------
BIL 066 046/073 050/078 048/077 053/081 053/077 051/078
2/T 33/T 43/T 22/T 22/T 33/T 33/T
LVM 066 043/065 041/071 040/078 041/082 042/078 041/076
5/T 65/T 44/T 32/T 23/T 33/T 33/T
HDN 070 048/077 050/081 048/079 053/082 052/080 051/080
1/N 22/T 23/T 22/T 23/T 33/T 33/T
MLS 065 046/072 051/081 051/079 057/084 058/079 054/080
1/N 11/N 23/T 23/T 33/T 44/T 33/T
4BQ 065 046/074 052/082 050/081 055/087 052/081 052/082
1/N 11/N 13/T 22/T 33/T 33/T 33/T
BHK 061 042/066 048/078 050/073 056/079 056/077 052/077
1/N 11/N 13/T 24/T 43/T 33/T 33/T
SHR 066 045/075 047/079 046/079 048/085 048/079 046/077
2/T 22/T 23/T 22/T 22/T 23/T 33/T
&&
.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...NONE.
WY...NONE.
&&
$$
WEATHER.GOV/BILLINGS
000
FXUS65 KBYZ 221242
AFDBYZ
AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE BILLINGS MT
642 AM MDT WED MAY 22 2013
.UPDATE...
MADE A UPDATE TO DROP POPS OVER FALLON AND CARTER COUNTIES. UPPER
SUPPORT WAS WANING AND DRIER AIR ALOFT WAS WORKING INTO THIS AREA.
BOWMAN RADAR RETURNS WERE DRYING UP. UPDATED ZFP ALREADY SENT. TWH
&&
.SHORT TERM...VALID FOR TDY AND THU...
THE DEEP UPPER LOW OVER SOUTHWEST MINNESOTA WILL FINALLY LOSE ITS
GRIP ON THE EAST TODAY. LOW CLOUDS STILL PRESENT OVER THE EAST
THIS MORNING WITH EVEN SOME LIGHT SHOWERS OR SPRINKLES MOVING WEST
FROM NORTH DAKOTA INTO FALLON AND CARTER COUNTIES. WILL HAVE LOW
POPS IN THESE TWO COUNTIES THIS MORNING. RIDGING SHOULD MOVE INTO
THE EAST LATE THIS MORNING AND CLEAR THE CLOUD COVER OUT. THE
FOCUS THEN TURNS TO THE OTHER DEEP LOW OVER NORTH AMERICA...OVER
THE PACIFIC NORTHWEST.
THIS WESTERN LOW WILL EDGE SLOWLY EASTWARD TODAY AND INCREASE
UPPER DIVERGENCE OVER THE WESTERN PART OF THE FORECAST AREA. SHEAR
INCREASES OVER THE WEST...BUT CAPE SEEMS LIMITED. DEWPOINTS WERE
CURRENTLY IN THE UPPER 30S AT LIVINGSTON AND PROGGED TO ONLY RISE
INTO THE MID 40S THIS AFTERNOON. EASTERLY WINDS WILL BE PRESENT
OVER THE ENTIRE AREA TODAY AND THIS WILL PROVIDE A CAP ABOVE 750MB
INHIBITING SURFACE BASED CONVECTION. MID LEVEL CAPES WERE NOT THAT
HIGH DESPITE INCREASING SHEAR. DIVERGENCE AND MOUNTAINOUS TERRAIN
SHOULD TRIGGER CONVECTION OVER SOUTHWEST MONTANA TODAY AND LIFT
THE STORMS NORTHEAST THIS AFTERNOON. MODELS HAVE BEEN PERSISTENT
ON THAT. WILL KEEP HIGH POPS FOR THE WEST. PRECIPITABLE WATER
AMOUNTS AROUND .75 WOULD PRODUCE LOCALLY HEAVY RAINS...BUT STORM
MOTION SHOULD BE ENOUGH TO LIMIT FLOOD POTENTIAL. AS FAR AS SEVERE
POTENTIAL TODAY GOES...BELIEVE THERE IS A THREAT FOR SOME HAIL
GIVEN THE SHEAR...BUT CAP AND WEAK CAPE SHOULD KEEP MOST ACTIVITY
BELOW SEVERE LEVELS.
FOR THURSDAY...SOUTHEAST WINDS WILL INCREASE OVER THE EAST. IN
FACT...WIND GUSTS TO 50 MPH WILL BE POSSIBLE AT BAKER WITH
SUSTAINED WINDS UP TO 35 MPH AS A SURFACE LOW DEEPENS OVER THE
WEST. THESE WINDS WILL KEEP THE EAST CAPPED FROM CONVECTION.
ORDINARILY EAST TO SOUTHEAST WINDS WOULD BRING IN HIGHER DEWPOINTS
BUT THAT DOES NOT APPEAR TO THE BE THE CASE THIS TIME. DEWPOINTS
IN THE DAKOTAS WERE IN THE MID TO UPPER 40S...SO THAT LOOKS TO BE
THE LIMIT FOR THE FORECAST AREA ON THURSDAY. DEWPOINTS BELOW 50
WOULD LIMIT SEVERE POTENTIAL OVER CENTRAL AND WESTERN ZONES.
CONVECTION SHOULD TRIGGER WITH SHORTWAVES SPINNING OFF THE WESTERN
LOW AND IN AMONGST SOME SURFACE CONVERGENCE WITH THE LOW. CAPE
INCREASES OVER CENTRAL ZONES DURING THE AFTERNOON. THE CAP LOOKS
TO BE DISMISSED DURING THE AFTERNOON AS EAST WINDS DECREASE OVER
CENTRAL AND WESTERN ZONES. ABOUT 30-35KTS OF SHEAR SHOULD BE
PRESENT BUT AGAIN CAPES LOOK ON THE LOW SIDE DUE TO LOWER
DEWPOINTS. COULD BE A HAIL THREAT WITH SHEAR PRESENT. ANY SEVERE
CONVECTION SHOULD BE ISOLATED WITH THE MAIN THREAT BEING LOCALLY
HEAVY RAIN WITH...PWATS AROUND .75...AND HAIL DUE TO SHEAR. WILL
OPT TO NOT MENTION SEVERE IN THE ZONES BUT FOLKS SHOULD BE
PREPARED FOR THE POSSIBILITY OF STRONG THUNDERSTORMS BOTH TODAY
WEST AND THURSDAY OVER CENTRAL AND WEST. WILL KEEP MENTION OF
ISOLATED SEVERE IN THE HWO ALONG WITH THE STRONG SOUTHEAST WINDS
OVER FALLON AND CARTER COUNTIES THURSDAY. WARMER TEMPERATURES
EXPECTED THURSDAY AS THE CAP WEAKENS. TWH
.LONG TERM...VALID FOR FRI...SAT...SUN...MON...TUE...
A FEW MINOR CHANGES TO THE EXTENDED PERIOD...BUT OVERALL FORECAST
LOOKS LIKE IT SHOULD BE IN PRETTY GOOD SHAPE.
MODELS APPEAR IN PRETTY GOOD AGREEMENT THROUGH ABOUT
SUNDAY...WITH UPPER LEVEL LOW PRESSURE SYSTEM OVER THE PACIFIC
NORTHWEST LIFTING SLOWLY TO THE NORTHEAST. THIS WILL KEEP THE
REGION IN PERSISTENT SOUTHWEST FLOW ALOFT. EASTERLY SURFACE FLOW
DEVELOPS BY SATURDAY...WITH LLJ TAKING SHAPE IN EASTERN ZONES AND
STRENGTHENING THROUGH SUNDAY. THIS SHOULD BRING ADDED INSTABILITY
AND MOISTURE TO THE SYSTEM AS WELL. MODELS THEN FAVOR A TROF...IN
SOME SHAPE...PUSHING ACROSS THE REGION FOR MONDAY THROUGH
WEDNESDAY. THE GFS IS LEANING TOWARD A DEEPER SLOW MOVING TROF...
WHILE EC FAVORS A MORE SHALLOW...SOMEWHAT NEGATIVELY TILTED TROF
THAT KICKS THROUGH THE REGION MUCH MORE QUICKLY...BUT KEEPS
SOUTHWEST SLOW INTACT ACROSS THE REGION. HAVE KEPT CLIMO TYPE...TO
SLIGHTLY HIGHER POPS IN PLACE ACROSS THE REGION THROUGHOUT THE
BULK OF THE PERIOD.
AS FOR TEMPERATURES...EXPECT TO SEE SLIGHTLY ABOVE NORMAL TEMPS
THROUGH THE PERIOD. MODELS CAME IN WARMER THROUGH MUCH OF THE
PERIOD...SO TRENDED TEMPS UP SLIGHTLY. AAG
&&
.AVIATION...
SHOWERS HAVE CLEARED IN THE EAST...BUT CIGS HAVE DROPPED TO MVFR
FROM KMLS EAST. WINDS HAVE ALSO TAPERED OFF SIGNIFICANTLY ACROSS
THE REGION...WITH THE EXCEPTION OF KLVM...WHERE WINDS STILL GUST
TO AROUND 30 KNOTS. GUSTY EAST WINDS ARE EXPECTED TO REDEVELOP BY
MID DAY TODAY.
MORE WIDESPREAD THUNDERSTORM ACTIVITY IS EXPECTED WEST OF
KBIL...INCLUDING NEAR KLVM. SOME OF THE THUNDERSTORMS ACROSS THE
WEST THIS AFTERNOON MAY BE STRONG. AAG
&&
.PRELIMINARY POINT TEMP/POPS...
TDY THU FRI SAT SUN MON TUE
-------------------------------------------------------
BIL 066 046/073 050/078 048/077 053/081 053/077 051/078
2/T 33/T 43/T 22/T 22/T 33/T 33/T
LVM 066 043/065 041/071 040/078 041/082 042/078 041/076
5/T 65/T 44/T 32/T 23/T 33/T 33/T
HDN 070 048/077 050/081 048/079 053/082 052/080 051/080
1/N 22/T 23/T 22/T 23/T 33/T 33/T
MLS 065 046/072 051/081 051/079 057/084 058/079 054/080
1/N 11/N 23/T 23/T 33/T 44/T 33/T
4BQ 065 046/074 052/082 050/081 055/087 052/081 052/082
1/N 11/N 13/T 22/T 33/T 33/T 33/T
BHK 061 042/066 048/078 050/073 056/079 056/077 052/077
1/N 11/N 13/T 24/T 43/T 33/T 33/T
SHR 066 045/075 047/079 046/079 048/085 048/079 046/077
2/T 22/T 23/T 22/T 22/T 23/T 33/T
&&
.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...NONE.
WY...NONE.
&&
$$
WEATHER.GOV/BILLINGS
000
FXUS65 KBYZ 220932
AFDBYZ
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BILLINGS MT
332 AM MDT WED MAY 22 2013
.SHORT TERM...VALID FOR TDY AND THU...
THE DEEP UPPER LOW OVER SOUTHWEST MINNESOTA WILL FINALLY LOSE ITS
GRIP ON THE EAST TODAY. LOW CLOUDS STILL PRESENT OVER THE EAST
THIS MORNING WITH EVEN SOME LIGHT SHOWERS OR SPRINKLES MOVING WEST
FROM NORTH DAKOTA INTO FALLON AND CARTER COUNTIES. WILL HAVE LOW
POPS IN THESE TWO COUNTIES THIS MORNING. RIDGING SHOULD MOVE INTO
THE EAST LATE THIS MORNING AND CLEAR THE CLOUD COVER OUT. THE
FOCUS THEN TURNS TO THE OTHER DEEP LOW OVER NORTH AMERICA...OVER
THE PACIFIC NORTHWEST.
THIS WESTERN LOW WILL EDGE SLOWLY EASTWARD TODAY AND INCREASE
UPPER DIVERGENCE OVER THE WESTERN PART OF THE FORECAST AREA. SHEAR
INCREASES OVER THE WEST...BUT CAPE SEEMS LIMITED. DEWPOINTS WERE
CURRENTLY IN THE UPPER 30S AT LIVINGSTON AND PROGGED TO ONLY RISE
INTO THE MID 40S THIS AFTERNOON. EASTERLY WINDS WILL BE PRESENT
OVER THE ENTIRE AREA TODAY AND THIS WILL PROVIDE A CAP ABOVE 750MB
INHIBITING SURFACE BASED CONVECTION. MID LEVEL CAPES WERE NOT THAT
HIGH DESPITE INCREASING SHEAR. DIVERGENCE AND MOUNTAINOUS TERRAIN
SHOULD TRIGGER CONVECTION OVER SOUTHWEST MONTANA TODAY AND LIFT
THE STORMS NORTHEAST THIS AFTERNOON. MODELS HAVE BEEN PERSISTENT
ON THAT. WILL KEEP HIGH POPS FOR THE WEST. PRECIPITABLE WATER
AMOUNTS AROUND .75 WOULD PRODUCE LOCALLY HEAVY RAINS...BUT STORM
MOTION SHOULD BE ENOUGH TO LIMIT FLOOD POTENTIAL. AS FAR AS SEVERE
POTENTIAL TODAY GOES...BELIEVE THERE IS A THREAT FOR SOME HAIL
GIVEN THE SHEAR...BUT CAP AND WEAK CAPE SHOULD KEEP MOST ACTIVITY
BELOW SEVERE LEVELS.
FOR THURSDAY...SOUTHEAST WINDS WILL INCREASE OVER THE EAST. IN
FACT...WIND GUSTS TO 50 MPH WILL BE POSSIBLE AT BAKER WITH
SUSTAINED WINDS UP TO 35 MPH AS A SURFACE LOW DEEPENS OVER THE
WEST. THESE WINDS WILL KEEP THE EAST CAPPED FROM CONVECTION.
ORDINARILY EAST TO SOUTHEAST WINDS WOULD BRING IN HIGHER DEWPOINTS
BUT THAT DOES NOT APPEAR TO THE BE THE CASE THIS TIME. DEWPOINTS
IN THE DAKOTAS WERE IN THE MID TO UPPER 40S...SO THAT LOOKS TO BE
THE LIMIT FOR THE FORECAST AREA ON THURSDAY. DEWPOINTS BELOW 50
WOULD LIMIT SEVERE POTENTIAL OVER CENTRAL AND WESTERN ZONES.
CONVECTION SHOULD TRIGGER WITH SHORTWAVES SPINNING OFF THE WESTERN
LOW AND IN AMONGST SOME SURFACE CONVERGENCE WITH THE LOW. CAPE
INCREASES OVER CENTRAL ZONES DURING THE AFTERNOON. THE CAP LOOKS
TO BE DISMISSED DURING THE AFTERNOON AS EAST WINDS DECREASE OVER
CENTRAL AND WESTERN ZONES. ABOUT 30-35KTS OF SHEAR SHOULD BE
PRESENT BUT AGAIN CAPES LOOK ON THE LOW SIDE DUE TO LOWER
DEWPOINTS. COULD BE A HAIL THREAT WITH SHEAR PRESENT. ANY SEVERE
CONVECTION SHOULD BE ISOLATED WITH THE MAIN THREAT BEING LOCALLY
HEAVY RAIN WITH...PWATS AROUND .75...AND HAIL DUE TO SHEAR. WILL
OPT TO NOT MENTION SEVERE IN THE ZONES BUT FOLKS SHOULD BE
PREPARED FOR THE POSSIBILITY OF STRONG THUNDERSTORMS BOTH TODAY
WEST AND THURSDAY OVER CENTRAL AND WEST. WILL KEEP MENTION OF
ISOLATED SEVERE IN THE HWO ALONG WITH THE STRONG SOUTHEAST WINDS
OVER FALLON AND CARTER COUNTIES THURSDAY. WARMER TEMPERATURES
EXPECTED THURSDAY AS THE CAP WEAKENS. TWH
.LONG TERM...VALID FOR FRI...SAT...SUN...MON...TUE...
A FEW MINOR CHANGES TO THE EXTENDED PERIOD...BUT OVERALL FORECAST
LOOKS LIKE IT SHOULD BE IN PRETTY GOOD SHAPE.
MODELS APPEAR IN PRETTY GOOD AGREEMENT THROUGH ABOUT
SUNDAY...WITH UPPER LEVEL LOW PRESSURE SYSTEM OVER THE PACIFIC
NORTHWEST LIFTING SLOWLY TO THE NORTHEAST. THIS WILL KEEP THE
REGION IN PERSISTENT SOUTHWEST FLOW ALOFT. EASTERLY SURFACE FLOW
DEVELOPS BY SATURDAY...WITH LLJ TAKING SHAPE IN EASTERN ZONES AND
STRENGTHENING THROUGH SUNDAY. THIS SHOULD BRING ADDED INSTABILITY
AND MOISTURE TO THE SYSTEM AS WELL. MODELS THEN FAVOR A TROF...IN
SOME SHAPE...PUSHING ACROSS THE REGION FOR MONDAY THROUGH
WEDNESDAY. THE GFS IS LEANING TOWARD A DEEPER SLOW MOVING TROF...
WHILE EC FAVORS A MORE SHALLOW...SOMEWHAT NEGATIVELY TILTED TROF
THAT KICKS THROUGH THE REGION MUCH MORE QUICKLY...BUT KEEPS
SOUTHWEST SLOW INTACT ACROSS THE REGION. HAVE KEPT CLIMO TYPE...TO
SLIGHTLY HIGHER POPS IN PLACE ACROSS THE REGION THROUGHOUT THE
BULK OF THE PERIOD.
AS FOR TEMPERATURES...EXPECT TO SEE SLIGHTLY ABOVE NORMAL TEMPS
THROUGH THE PERIOD. MODELS CAME IN WARMER THROUGH MUCH OF THE
PERIOD...SO TRENDED TEMPS UP SLIGHTLY. AAG
&&
.AVIATION...
SHOWERS HAVE CLEARED IN THE EAST...BUT CIGS HAVE DROPPED TO MVFR
FROM KMLS EAST. WINDS HAVE ALSO TAPERED OFF SIGNIFICANTLY ACROSS
THE REGION...WITH THE EXCEPTION OF KLVM...WHERE WINDS STILL GUST
TO AROUND 30 KNOTS. GUSTY EAST WINDS ARE EXPECTED TO REDEVELOP BY
MID DAY TODAY.
MORE WIDESPREAD THUNDERSTORM ACTIVITY IS EXPECTED WEST OF
KBIL...INCLUDING NEAR KLVM. SOME OF THE THUNDERSTORMS ACROSS THE
WEST THIS AFTERNOON MAY BE STRONG. AAG
&&
.PRELIMINARY POINT TEMP/POPS...
TDY THU FRI SAT SUN MON TUE
-------------------------------------------------------
BIL 066 046/073 050/078 048/077 053/081 053/077 051/078
2/T 33/T 43/T 22/T 22/T 33/T 33/T
LVM 066 043/065 041/071 040/078 041/082 042/078 041/076
5/T 65/T 44/T 32/T 23/T 33/T 33/T
HDN 070 048/077 050/081 048/079 053/082 052/080 051/080
1/N 22/T 23/T 22/T 23/T 33/T 33/T
MLS 065 046/072 051/081 051/079 057/084 058/079 054/080
1/N 11/N 23/T 23/T 33/T 44/T 33/T
4BQ 065 046/074 052/082 050/081 055/087 052/081 052/082
1/N 11/N 13/T 22/T 33/T 33/T 33/T
BHK 061 042/066 048/078 050/073 056/079 056/077 052/077
2/W 11/N 13/T 24/T 43/T 33/T 33/T
SHR 066 045/075 047/079 046/079 048/085 048/079 046/077
2/T 22/T 23/T 22/T 22/T 23/T 33/T
&&
.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...NONE.
WY...NONE.
&&
$$
WEATHER.GOV/BILLINGS
000
FXUS65 KBYZ 220108
AFDBYZ
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BILLINGS MT
708 PM MDT TUE MAY 21 2013
.UPDATE...
UPDATED THE FORECAST TO INCREASE POPS AND SHOWER COVERAGE ACROSS
THE WEST THIS EVENING AS SHORTWAVE ENERGY AND INCREASING UPPER
LEVEL DIFFLUENCE HELP GENERATE SOME WEAK CONVECTION. EXPECT THE
SHOWERS AND ISOLATED THUNDERSTORMS TO DISSIPATE OVERNIGHT WITH THE
LOSS OF DAYTIME HEATING AND AS SHORTWAVE ENERGY CONTINUES TO MOVE
AWAY FROM THAT AREA.
ALSO EXPANDED THE POTENTIAL FOR SHOWERS ACROSS THE EAST A BIT
FARTHER WEST...TO INCLUDE AREAS SUCH AS BROADUS AND MILES CITY
THIS EVENING. RADAR...SATELLITE...AND OBS ALL SUPPORT THIS
WESTWARD EXPANSION. ANTICIPATE THAT THIS AREA OF RAIN SHOWERS WILL
BE SLOWLY PUSHED EASTWARD OVERNIGHT AS UPPER LEVEL RIDGING BEGINS
TO BUILD IN FROM THE WEST...AHEAD OF THE APPROACHING UPPER LEVEL
LOW CURRENTLY SITUATED OVER THE PACIFIC NORTHWEST. THE REST OF THE
FORECAST IS ON TRACK. STC
&&
.SHORT TERM...VALID FOR WED AND THU...
LARGE UPPER LOW OVER THE EASTERN DAKOTAS CONTINUES TO IMPACT OUR
FAR EASTERN ZONES THIS AFTERNOON AND WILL CONTINUE THROUGHOUT THE
NIGHT. EXPECT MOSTLY CLOUDY SKIES ALONG WITH A SLIGHT SHOWER
CHANCE FROM CUSTER AND POWDER RIVER COUNTIES EASTWARD.
ELSEWHERE...SOME CLOUDS AND AN ISOLATED SHOWER WILL BE POSSIBLE
OVER THE BEARTOOTH/ABSAROKA MOUNTAINS THIS EVENING WITH CLEAR TO
PARTLY CLOUDY SKIES EXPECTED ACROSS OUR CENTRAL AREAS.
LARGE UPPER LOW AND TROUGH CURRENTLY MOVING ONTO THE PACIFIC
NORTHWEST COAST WILL MOVE ONSHORE DURING THE DAY WEDNESDAY. THIS
WILL PROVIDE A SOUTHERLY AND DIVERGENT FLOW ALOFT TO OUR FORECAST
AREA WEDNESDAY THROUGH THURSDAY. NUMEROUS PIECES OF ENERGY WILL
EJECT FROM THIS LOW BEGINNING WEDNESDAY AFTERNOON INTO THURSDAY
NIGHT. AT THE SAME TIME...A STRONG LOW-LEVEL JET WILL DEVELOP
ACROSS OUR EASTERN THIRD OF THE FORECAST AREA WEDNESDAY NIGHT INTO
THURSDAY PROVIDING EASTERLY SURFACE WINDS TO THE ENTIRE AREA. BEST
CHANCES FOR SHOWERS AND THUNDERSTORMS WILL BE FROM ABOUT
YELLOWSTONE COUNTY WESTWARD WEDNESDAY AFTERNOON INTO THURSDAY
NIGHT. HAVE RAISED POPS TO LIKELY FOR THE BEARTOOTH/ABSAROKA
MOUNTAINS AND FOOTHILLS...AS WELL AS FROM ABOUT REED POINT WEST
AND NORTH WEDNESDAY EVENING AND NIGHT AND WILL MAINTAIN HIGH
CHANCE POPS FOR THURSDAY FROM BILLINGS WESTWARD.
CAN`T RULE OUT SEVERE THUNDERSTORMS WEDNESDAY EVENING AND AGAIN
THURSDAY. THERE WILL BE GOOD SPEED AND DIRECTIONAL SHEAR...CAPE
AND LAPSE RATES ACROSS THE CENTRAL AND WESTERN AREAS.
HOWEVER...SOUNDINGS SHOW THE AREA CAPPED SO THUNDERSTORMS WOULD BE
MORE ELEVATED IN NATURE RESULTING IN MORE OF A LARGE HAIL THREAT.
HOOLEY
.LONG TERM...VALID FOR FRI...SAT...SUN...MON...TUE...
NOT MANY CHANGES MADE TO THE EXTENDED PERIOD FORECAST...AS
INHERITED FORECAST WAS IN DECENT SHAPE.
THE PERIOD BEGINS FRIDAY MORNING WITH THE REGION UNDER THE
INFLUENCE OF SOUTHWESTERLY FLOW ALOFT...PRIMARILY DUE TO THE
SPINNING LOW PRESSURE SYSTEM OVER THE PACIFIC NORTHWEST.
BY SATURDAY EVENING AN EASTERLY LOW LEVEL JET FORMS OVER THE
EASTERN PORTION OF MONTANA. THIS WILL HELP BRING SOME MOISTURE
AND ADDED INSTABILITY TO THE REGION. EXPECT WINDS TO BE BLOWING
PRETTY GOOD IN PARTS OF FALLON AND CARTER COUNTIES AS THIS JET
STRENGTHENS BY SUNDAY AFTERNOON.
DUE TO THE NATURE OF THE PATTERN ALOFT...COUPLED WITH THE
PRESENCE OF SOME MOISTURE AT THE SURFACE...CANNOT RULE OUT THE
POTENTIAL FOR THUNDERSTORM ACTIVITY ALMOST EVERY DAY IN THE
PERIOD. SEVERITY WILL DEPEND ON AMOUNT OF DRY AIR ENTRAINMENT AT
MID LEVELS...ESPECIALLY DURING THIS UPCOMING WEEKEND. CAPE VALUES
IN THE EASTERN ZONES WILL EXCEED 1000 J/KG AT TIMES...SO THIS
NEEDS TO BE MONITORED.
FOR THE REST OF THE PERIOD...THE REGION WILL CONTINUE TO BE UNDER
THE INFLUENCE OF SW FLOW ALOFT...BEFORE THE MAIN FLOW BECOMES MORE
ZONAL. SINGER
&&
.AVIATION...
RAIN SHOWERS WILL CONTINUE TO BRING MVFR/IFR CONDITIONS TO AREAS
FROM KMLS EAST THROUGH A GOOD PORTION OF TONIGHT. THE MVFR/IFR
POTENTIAL WILL BEGIN TO DIMINISH ACROSS THE EAST LATE TONIGHT
INTO EARLY WEDNESDAY MORNING.
AN ISOLATED SHOWER OR THUNDERSTORM IS POSSIBLE THROUGH
LATE THIS EVENING NEAR THE BEARTOOTH MOUNTAINS...WHICH WOULD
REDUCE VISIBILITIES AND INCREASE WIND GUST POTENTIAL. WEDNESDAY
AFTERNOON...THE POTENTIAL FOR MORE WIDESPREAD THUNDERSTORM
ACTIVITY INCREASES WEST OF BILLINGS...INCLUDING NEAR KLVM. SOME OF
THE THUNDERSTORMS ACROSS THE WEST WEDNESDAY AFTERNOON MAY BE
STRONG.
GUSTY E WINDS WILL WEAKEN LATE TONIGHT ACROSS THE WEST...BUT WILL
INCREASE ACROSS THE ENTIRE REGION AGAIN BY MID DAY WEDNESDAY. STC
&&
.PRELIMINARY POINT TEMP/POPS...
WED THU FRI SAT SUN MON TUE
-----------------------------------------------------------
BIL 043/066 046/074 050/072 048/077 053/079 053/077 051/077
12/T 33/T 43/T 22/T 22/T 23/T 33/T
LVM 039/066 043/065 041/068 040/078 041/080 042/078 041/075
24/T 64/T 44/T 32/T 22/T 23/T 33/T
HDN 043/070 048/077 050/075 048/079 053/080 052/080 051/079
11/N 32/T 33/T 22/T 22/T 23/T 33/T
MLS 042/065 046/072 051/077 051/079 057/082 058/079 054/079
31/N 12/W 23/T 22/T 23/T 33/T 33/T
4BQ 040/065 046/074 052/079 050/081 055/085 052/081 052/081
31/N 11/N 13/T 22/T 23/T 33/T 33/T
BHK 039/061 042/066 048/074 050/073 056/077 056/077 052/076
41/N 11/N 13/T 22/T 33/T 33/T 33/T
SHR 037/066 045/075 047/075 046/079 048/083 048/079 046/076
12/T 32/T 23/T 22/T 22/T 23/T 33/T
&&
.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...NONE.
WY...NONE.
&&
$$
WEATHER.GOV/BILLINGS
000
FXUS65 KBYZ 212031
AFDBYZ
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BILLINGS MT
231 PM MDT TUE MAY 21 2013
.SHORT TERM...VALID FOR WED AND THU...
LARGE UPPER LOW OVER THE EASTERN DAKOTAS CONTINUES TO IMPACT OUR
FAR EASTERN ZONES THIS AFTERNOON AND WILL CONTINUE THROUGHOUT THE
NIGHT. EXPECT MOSTLY CLOUDY SKIES ALONG WITH A SLIGHT SHOWER
CHANCE FROM CUSTER AND POWDER RIVER COUNTIES EASTWARD.
ELSEWHERE...SOME CLOUDS AND AN ISOLATED SHOWER WILL BE POSSIBLE
OVER THE BEARTOOTH/ABSAROKA MOUNTAINS THIS EVENING WITH CLEAR TO
PARTLY CLOUDY SKIES EXPECTED ACROSS OUR CENTRAL AREAS.
LARGE UPPER LOW AND TROUGH CURRENTLY MOVING ONTO THE PACIFIC
NORTHWEST COAST WILL MOVE ONSHORE DURING THE DAY WEDNESDAY. THIS
WILL PROVIDE A SOUTHERLY AND DIVERGENT FLOW ALOFT TO OUR FORECAST
AREA WEDNESDAY THROUGH THURSDAY. NUMEROUS PIECES OF ENERGY WILL
EJECT FROM THIS LOW BEGINNING WEDNESDAY AFTERNOON INTO THURSDAY
NIGHT. AT THE SAME TIME...A STRONG LOW-LEVEL JET WILL DEVELOP
ACROSS OUR EASTERN THIRD OF THE FORECAST AREA WEDNESDAY NIGHT INTO
THURSDAY PROVIDING EASTERLY SURFACE WINDS TO THE ENTIRE AREA. BEST
CHANCES FOR SHOWERS AND THUNDERSTORMS WILL BE FROM ABOUT
YELLOWSTONE COUNTY WESTWARD WEDNESDAY AFTERNOON INTO THURSDAY
NIGHT. HAVE RAISED POPS TO LIKELY FOR THE BEARTOOTH/ABSAROKA
MOUNTAINS AND FOOTHILLS...AS WELL AS FROM ABOUT REED POINT WEST
AND NORTH WEDNESDAY EVENING AND NIGHT AND WILL MAINTAIN HIGH
CHANCE POPS FOR THURSDAY FROM BILLINGS WESTWARD.
CAN`T RULE OUT SEVERE THUNDERSTORMS WEDNESDAY EVENING AND AGAIN
THURSDAY. THERE WILL BE GOOD SPEED AND DIRECTIONAL SHEAR...CAPE
AND LAPSE RATES ACROSS THE CENTRAL AND WESTERN AREAS.
HOWEVER...SOUNDINGS SHOW THE AREA CAPPED SO THUNDERSTORMS WOULD BE
MORE ELEVATED IN NATURE RESULTING IN MORE OF A LARGE HAIL THREAT.
HOOLEY
.LONG TERM...VALID FOR FRI...SAT...SUN...MON...TUE...
NOT MANY CHANGES MADE TO THE EXTENDED PERIOD FORECAST...AS
INHERITED FORECAST WAS IN DECENT SHAPE.
THE PERIOD BEGINS FRIDAY MORNING WITH THE REGION UNDER THE
INFLUENCE OF SOUTHWESTERLY FLOW ALOFT...PRIMARILY DUE TO THE
SPINNING LOW PRESSURE SYSTEM OVER THE PACIFIC NORTHWEST.
BY SATURDAY EVENING AN EASTERLY LOW LEVEL JET FORMS OVER THE
EASTERN PORTION OF MONTANA. THIS WILL HELP BRING SOME MOISTURE
AND ADDED INSTABILITY TO THE REGION. EXPECT WINDS TO BE BLOWING
PRETTY GOOD IN PARTS OF FALLON AND CARTER COUNTIES AS THIS JET
STRENGTHENS BY SUNDAY AFTERNOON.
DUE TO THE NATURE OF THE PATTERN ALOFT...COUPLED WITH THE
PRESENCE OF SOME MOISTURE AT THE SURFACE...CANNOT RULE OUT THE
POTENTIAL FOR THUNDERSTORM ACTIVITY ALMOST EVERY DAY IN THE
PERIOD. SEVERITY WILL DEPEND ON AMOUNT OF DRY AIR ENTRAINMENT AT
MID LEVELS...ESPECIALLY DURING THIS UPCOMING WEEKEND. CAPE VALUES
IN THE EASTERN ZONES WILL EXCEED 1000 J/KG AT TIMES...SO THIS
NEEDS TO BE MONITORED.
FOR THE REST OF THE PERIOD...THE REGION WILL CONTINUE TO BE UNDER
THE INFLUENCE OF SW FLOW ALOFT...BEFORE THE MAIN FLOW BECOMES MORE
ZONAL. SINGER
&&
.AVIATION...
VFR CONDITIONS SHOULD PREVAIL AT ALL TERMINALS THROUGH THIS
EVENING AND TONIGHT. HOWEVER...CANNOT RULE OUT AN ISOLATED SHOWER
OR THUNDERSTORM NEAR THE BEARTOOTH AND SHERIDAN FOOTHILLS...WHICH
WOULD REDUCE VISIBILITIES AND INCREASE WIND GUST POTENTIAL. SINGER
&&
.PRELIMINARY POINT TEMP/POPS...
WED THU FRI SAT SUN MON TUE
-----------------------------------------------------------
BIL 043/066 046/074 050/072 048/077 053/079 053/077 051/077
12/T 33/T 43/T 22/T 22/T 23/T 33/T
LVM 039/066 043/065 041/068 040/078 041/080 042/078 041/075
14/T 64/T 44/T 32/T 22/T 23/T 33/T
HDN 043/070 048/077 050/075 048/079 053/080 052/080 051/079
11/N 32/T 33/T 22/T 22/T 23/T 33/T
MLS 042/065 046/072 051/077 051/079 057/082 058/079 054/079
11/N 12/W 23/T 22/T 23/T 33/T 33/T
4BQ 040/065 046/074 052/079 050/081 055/085 052/081 052/081
11/N 11/N 13/T 22/T 23/T 33/T 33/T
BHK 039/061 042/066 048/074 050/073 056/077 056/077 052/076
31/N 11/N 13/T 22/T 33/T 33/T 33/T
SHR 037/066 045/075 047/075 046/079 048/083 048/079 046/076
12/T 32/T 23/T 22/T 22/T 23/T 33/T
&&
.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...NONE.
WY...NONE.
&&
$$
WEATHER.GOV/BILLINGS
000
FXUS65 KBYZ 211512
AFDBYZ
AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE BILLINGS MT
912 AM MDT TUE MAY 21 2013
.UPDATE...
LARGE UPPER LOW OVER THE EASTERN DAKOTAS WILL CONTINUE TO ROTATE
CLOUDS WESTWARD ACROSS EASTERN MONTANA TODAY. RAIN SHOWERS WILL
CONTINUE TO BE POSSIBLE MAINLY EAST OF A MILES CITY TO BROADUS
LINE TODAY BUT THESE WILL BE SHIFTING EAST BY LATE AFTERNOON.
EXPECT A MOSTLY SUNNY AND MILDER DAY TODAY FOR THE REMAINDER OF
THE FORECAST AREA. PATCHY FOG WILL CONTINUE FOR THIS MORNING FOR
THE LIVINGSTON AREA BUT THIS HAS BEEN BREAKING UP DURING THE PAST
HOUR. CURRENT FORECAST IN GOOD SHAPE WITH NO UPDATES PLANNED THIS
MORNING. HOOLEY
&&
.SHORT TERM...VALID FOR TDY AND WED...
THE WEEKEND RAIN-MAKER WILL CONTINUE EXITING STAGE RIGHT...LEAVING
EASTERLY LOW-LEVEL FLOW IN PLAY THE NEXT SEVERAL DAYS OUT AHEAD OF
A 500-HPA LOW WHICH MOVES INTO THE PACIFIC NORTHWEST. THIS PATTERN
WILL YIELD SEASONABLE TEMPERATURES...AND SOME CHANCE OF STORMS FOR
SOUTH CENTRAL MT...ESPECIALLY LATER ON WED AND WED NIGHT.
TODAY...EARLY-MORNING RADAR TRENDS SUGGEST THAT LIKELY POPS REMAIN
NECESSARY AROUND BAKER AND EKALAKA INTO THE MORNING TO ACCOUNT FOR
RESIDUAL BANDS OF SHOWERS ROTATING WESTWARD INTO THAT AREA. THE 00
UTC GUIDANCE IS CLOSELY CLUSTERED IN ITS QPF OUTPUT...AND IT SHOWS
A SHARP WESTERN GRADIENT TO THE SHOWERS DICTATED BY A WEDGE OF DRY
AIR OVER CENTRAL MT. SURFACE OBSERVATIONS AS OF 09 UTC SUGGEST THE
LOW- AND MID-LEVEL DRYING IS BEGINNING TO INFLUENCE THE MILES CITY
AREA...AND MOST 00 UTC GUIDANCE KEEPS SHOWERS EAST OF THERE TODAY.
EVEN RECENT RAP RUNS AND THE 06 UTC NAM KEEP SHOWERS EAST OF MILES
CITY SO WE WENT WITH A DRY FORECAST THERE THIS MORNING. POPS OVER
THE BAKER AND EKALAKA AREAS DROP BACK TO THE CHANCE CATEGORY AFTER
18 UTC AS WELL SINCE MID-LEVEL FORCING AND MOISTURE ADVECTION WILL
BE WEAKENING BY THAT TIME. OTHERWISE...THE EASTERLY LOW-LEVEL FLOW
WILL BECOME ESTABLISHED OVER MUCH OF THE AREA BY AFTERNOON...WHICH
COULD HELP ASSIST WITH SOME CUMULUS DEVELOPMENT GIVEN THE RESIDUAL
NEAR-SURFACE MOISTURE AFTER WEEKEND RAINFALL. THERE IS JUST ENOUGH
INSTABILITY FORECAST BY THE 00 UTC GUIDANCE OVER THE MOUNTAINS FOR
US TO INCLUDE SLIGHT CHANCES OF CONVECTION AFTER 18 UTC THERE TOO.
HIGHS TODAY WERE LARGELY BASED ON A CONSENSUS OF 00 UTC MOS AS THE
EASTERLY FLOW WILL TEND TO LIMIT MIXING...AND USING BIAS-CORRECTED
FLAVORS OF GUIDANCE SEEMS A BIT DANGEROUS GIVEN NEW SOIL MOISTURE.
TONIGHT...QUIET CONDITIONS SHOULD PREVAIL...AND IN FACT BASED ON A
BLEND OF 00 UTC MOS OUTPUT...LOWS WILL PROBABLY BE BELOW NORMAL IN
MANY SPOTS. WE HAVE A DRY FORECAST IN PLAY AFTER 06 UTC EXCEPT FOR
EXTREME SOUTHEASTERN MT. WE WILL NEED TO BE MINDFULL FOR POTENTIAL
FOG DEVELOPMENT...BUT IT SEEMS THAT NEAR-SURFACE FLOW MIGHT END UP
STAYING JUST STRONG ENOUGH TO PREVENT ITS FORMATION...SO IT IS NOT
IN THE FORECAST AT THIS POINT.
WED INTO WED NIGHT...A BETTER CHANCE OF CONVECTION WILL EXIST OVER
SOUTH CENTRAL MT AS MID-LEVEL LAPSE RATES STEEPEN TO AROUND 7 C/KM
ON STRENGTHENING SOUTHERLY FLOW ALOFT. MOST 00 UTC MODEL SOLUTIONS
GENERATE CONVECTION TOWARD 00 UTC...SO OUR GOING CHANCE-STYLE POPS
ARE CERTAINLY WARRANTED. THE ONLY QUESTION MARK MIGHT BE TIMING OR
EASTWARD EXTENT OF THE WEAK SHORT WAVE THAT GUIDANCE KEYS IN ON TO
YIELD CONVECTION...ESPECIALLY SINCE THE MERIDIONAL FLOW MIGHT TAKE
IT FURTHER WEST THAN EXPECTED. THERE IS PROBABLY A NON-ZERO THREAT
OF SEVERE WEATHER IF STORMS DEVELOP...BUT IT WILL BE KEPT IN CHECK
BY A LACK OF BUOYANCY /MUCAPE 500 J/KG OR LESS/. OVER SOUTHEASTERN
MT...STORM CHANCES ARE MINIMAL OWING TO MID-LEVEL RIDGING. SCHULTZ
.LONG TERM...VALID FOR THU...FRI...SAT...SUN...MON...
MEDIUM RANGE MODELS WERE PRETTY CONSISTENT THROUGH THE PERIOD
WITH SOME TIMING DIFFERENCES OF SHORTWAVES PROGGED TO GET KICKED
OUT OF A DEEP UPPER TROUGH OVER THE WEST MOVING INLAND.
THURSDAY COULD BE AN ACTIVE DAY FOR THUNDERSTORMS...MAINLY
CENTRAL AND WESTERN ZONES. THE DEEP WESTERN TROUGH ADVANCES EAST
SLOWLY AND LOWERS HEIGHTS THROUGH THE DAY. LOW LEVEL EAST TO
SOUTHEAST WINDS WILL ALLOW FOR DEWPOINTS TO HANG AROUND 50 DEGREES
OVER CENTRAL ZONES...WITH SLIGHTLY LOWER VALUES OVER THE WEST.
EFFECTIVE BULK SHEAR INCREASES TO AROUND 35KTS WITH CAPES REACHING
AS HIGH AS 1000 J/KG. STRONG SURFACE CONVERGENCE WITH SHORTWAVE
ENERGY WILL IGNITE THUNDERSTORMS OVER WESTERN ZONES IN THE
AFTERNOON. STORMS WILL MOVE NORTH TO NORTHEAST AND KICK OUT OF THE
FORECAST FAIRLY QUICKLY IN THE EVENING. SHEAR WOULD BE STRONG
ENOUGH TO PRODUCE SOME STRONG STORMS WITH THE MAIN THREAT BEING
HAIL. WILL HAVE TO WATCH THIS EVENT FOR A POSSIBLE SEVERE WEATHER
DAY. WILL MENTION STRONG STORMS IN THE HWO.
FRIDAY IS A DAY A BIT IN QUESTION AS MODELS DIFFER ON TIMING AND
STRENGTH OF A SHORTWAVE KICKING OFF THE MAIN LOW TO THE WEST. THE
ECMWF WAS STRONGEST AND SLOWEST WITH THIS WAVE AS IT CROSSES THE
FORECAST AREA DURING THE DAY. THE GFS WAS WEAKER AND TAKES IT
ACROSS LATE THURSDAY NIGHT. THE ECMWF WOULD BE WETTER. INHERITED
SCATTERED POPS FOR FRIDAY...BUT IF THE GFS WAS RIGHT...IT WILL BE
DRIER.
DRIER MID LEVEL AIR WILL RUSH IN BEHIND THE SHORTWAVE REGARDLESS
OF THE TIMING. THIS WILL SET UP A MAINLY DRY PERIOD FOR THE
WEEKEND WITH THE MAIN ENERGY STAYING NORTH. HIGH BASED SHOWERS OR
THUNDERSTORMS CAN NOT BE RULED OUT OVER THE WEEKEND THOUGH AS
MODELS KICK DISTURBANCES ACROSS IN SOUTHWEST FLOW. DEWPOINTS
SHOULD BE MUCH LOWER AND THESE SHOWERS WILL NOT CONTAIN A GREAT
DEAL OF PRECIPITATION AND BE MORE WIND PRODUCERS. WILL KEEP POPS
LOW. TEMPERATURES SHOULD SLIGHTLY ABOVE SEASONAL AVERAGES THROUGH
PERIOD. TWH
&&
.AVIATION...
SOME LINGERING SHOWERS OVER KBHK SHOULD DISSIPATE BY THE EARLY
AFTERNOON. FOG IS SLOWLY LIFTING NEAR KLVM...BUT STILL MAY CAUSE
SOME IMPACTS...SO UPDATED THE KLVM TAF TO INCLUDE ONE MORE HOUR OF
LOWERED VISIBILITIES DUE TO FOG. THE REST OF THE AREA SHOULD
REMAIN UNDER VFR CONDITIONS TODAY...HOWEVER THERE IS A CHANCE FOR
AN ISOLATED SHOWER OR THUNDERSTORM...MOSTLY NEAR THE HIGHER
TERRAIN. SINGER
&&
.PRELIMINARY POINT TEMP/POPS...
TDY WED THU FRI SAT SUN MON
-------------------------------------------------------
BIL 067 043/068 047/074 050/075 048/077 051/077 051/073
1/B 12/T 33/T 43/T 22/T 22/T 23/T
LVM 069 039/067 044/065 041/068 040/075 041/076 042/070
1/F 14/T 45/T 43/T 22/T 22/T 23/T
HDN 069 043/070 048/077 050/078 048/079 051/080 051/076
1/B 12/T 33/T 33/T 22/T 22/T 23/T
MLS 059 044/067 047/073 053/075 051/078 055/078 054/076
1/E 11/B 11/N 23/T 22/T 23/T 33/T
4BQ 056 040/065 046/074 052/076 050/079 053/080 052/077
3/W 11/B 11/N 13/T 22/T 23/T 33/T
BHK 050 040/061 043/067 050/070 050/075 053/073 052/073
7/W 21/N 11/N 13/T 22/T 33/T 33/T
SHR 061 037/068 045/075 049/075 046/078 048/079 048/075
1/B 12/T 32/T 23/T 22/T 22/T 23/T
&&
.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...NONE.
WY...NONE.
&&
$$
WEATHER.GOV/BILLINGS
000
FXUS65 KBYZ 211213
AFDBYZ
AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE BILLINGS MT
613 AM MDT TUE MAY 21 2013
.UPDATE...
WE HAVE UPDATED THE FORECAST TO INCLUDE PATCHY DENSE FOG FOR PARTS
OF SOUTH CENTRAL MT THIS MORNING. LIGHT WINDS AND A MOIST BOUNDARY
LAYER ARE CONTRIBUTING TO FOG AS OF 12 UTC...ESPECIALLY AROUND THE
LIVINGSTON AREA WHERE VISIBILITY HAS FALLEN TO LESS THAN A QUARTER
MILE. THE FOG SHOULD BURN OFF BY MID TO LATE MORNING ONCE THE LOW-
LEVELS WARM WITH SUNSHINE. SCHULTZ
&&
.SHORT TERM...VALID FOR TDY AND WED...
THE WEEKEND RAIN-MAKER WILL CONTINUE EXITING STAGE RIGHT...LEAVING
EASTERLY LOW-LEVEL FLOW IN PLAY THE NEXT SEVERAL DAYS OUT AHEAD OF
A 500-HPA LOW WHICH MOVES INTO THE PACIFIC NORTHWEST. THIS PATTERN
WILL YIELD SEASONABLE TEMPERATURES...AND SOME CHANCE OF STORMS FOR
SOUTH CENTRAL MT...ESPECIALLY LATER ON WED AND WED NIGHT.
TODAY...EARLY-MORNING RADAR TRENDS SUGGEST THAT LIKELY POPS REMAIN
NECESSARY AROUND BAKER AND EKALAKA INTO THE MORNING TO ACCOUNT FOR
RESIDUAL BANDS OF SHOWERS ROTATING WESTWARD INTO THAT AREA. THE 00
UTC GUIDANCE IS CLOSELY CLUSTERED IN ITS QPF OUTPUT...AND IT SHOWS
A SHARP WESTERN GRADIENT TO THE SHOWERS DICTATED BY A WEDGE OF DRY
AIR OVER CENTRAL MT. SURFACE OBSERVATIONS AS OF 09 UTC SUGGEST THE
LOW- AND MID-LEVEL DRYING IS BEGINNING TO INFLUENCE THE MILES CITY
AREA...AND MOST 00 UTC GUIDANCE KEEPS SHOWERS EAST OF THERE TODAY.
EVEN RECENT RAP RUNS AND THE 06 UTC NAM KEEP SHOWERS EAST OF MILES
CITY SO WE WENT WITH A DRY FORECAST THERE THIS MORNING. POPS OVER
THE BAKER AND EKALAKA AREAS DROP BACK TO THE CHANCE CATEGORY AFTER
18 UTC AS WELL SINCE MID-LEVEL FORCING AND MOISTURE ADVECTION WILL
BE WEAKENING BY THAT TIME. OTHERWISE...THE EASTERLY LOW-LEVEL FLOW
WILL BECOME ESTABLISHED OVER MUCH OF THE AREA BY AFTERNOON...WHICH
COULD HELP ASSIST WITH SOME CUMULUS DEVELOPMENT GIVEN THE RESIDUAL
NEAR-SURFACE MOISTURE AFTER WEEKEND RAINFALL. THERE IS JUST ENOUGH
INSTABILITY FORECAST BY THE 00 UTC GUIDANCE OVER THE MOUNTAINS FOR
US TO INCLUDE SLIGHT CHANCES OF CONVECTION AFTER 18 UTC THERE TOO.
HIGHS TODAY WERE LARGELY BASED ON A CONSENSUS OF 00 UTC MOS AS THE
EASTERLY FLOW WILL TEND TO LIMIT MIXING...AND USING BIAS-CORRECTED
FLAVORS OF GUIDANCE SEEMS A BIT DANGEROUS GIVEN NEW SOIL MOISTURE.
TONIGHT...QUIET CONDITIONS SHOULD PREVAIL...AND IN FACT BASED ON A
BLEND OF 00 UTC MOS OUTPUT...LOWS WILL PROBABLY BE BELOW NORMAL IN
MANY SPOTS. WE HAVE A DRY FORECAST IN PLAY AFTER 06 UTC EXCEPT FOR
EXTREME SOUTHEASTERN MT. WE WILL NEED TO BE MINDFULL FOR POTENTIAL
FOG DEVELOPMENT...BUT IT SEEMS THAT NEAR-SURFACE FLOW MIGHT END UP
STAYING JUST STRONG ENOUGH TO PREVENT ITS FORMATION...SO IT IS NOT
IN THE FORECAST AT THIS POINT.
WED INTO WED NIGHT...A BETTER CHANCE OF CONVECTION WILL EXIST OVER
SOUTH CENTRAL MT AS MID-LEVEL LAPSE RATES STEEPEN TO AROUND 7 C/KM
ON STRENGTHENING SOUTHERLY FLOW ALOFT. MOST 00 UTC MODEL SOLUTIONS
GENERATE CONVECTION TOWARD 00 UTC...SO OUR GOING CHANCE-STYLE POPS
ARE CERTAINLY WARRANTED. THE ONLY QUESTION MARK MIGHT BE TIMING OR
EASTWARD EXTENT OF THE WEAK SHORT WAVE THAT GUIDANCE KEYS IN ON TO
YIELD CONVECTION...ESPECIALLY SINCE THE MERIDIONAL FLOW MIGHT TAKE
IT FURTHER WEST THAN EXPECTED. THERE IS PROBABLY A NON-ZERO THREAT
OF SEVERE WEATHER IF STORMS DEVELOP...BUT IT WILL BE KEPT IN CHECK
BY A LACK OF BUOYANCY /MUCAPE 500 J/KG OR LESS/. OVER SOUTHEASTERN
MT...STORM CHANCES ARE MINIMAL OWING TO MID-LEVEL RIDGING. SCHULTZ
.LONG TERM...VALID FOR THU...FRI...SAT...SUN...MON...
MEDIUM RANGE MODELS WERE PRETTY CONSISTENT THROUGH THE PERIOD
WITH SOME TIMING DIFFERENCES OF SHORTWAVES PROGGED TO GET KICKED
OUT OF A DEEP UPPER TROUGH OVER THE WEST MOVING INLAND.
THURSDAY COULD BE AN ACTIVE DAY FOR THUNDERSTORMS...MAINLY
CENTRAL AND WESTERN ZONES. THE DEEP WESTERN TROUGH ADVANCES EAST
SLOWLY AND LOWERS HEIGHTS THROUGH THE DAY. LOW LEVEL EAST TO
SOUTHEAST WINDS WILL ALLOW FOR DEWPOINTS TO HANG AROUND 50 DEGREES
OVER CENTRAL ZONES...WITH SLIGHTLY LOWER VALUES OVER THE WEST.
EFFECTIVE BULK SHEAR INCREASES TO AROUND 35KTS WITH CAPES REACHING
AS HIGH AS 1000 J/KG. STRONG SURFACE CONVERGENCE WITH SHORTWAVE
ENERGY WILL IGNITE THUNDERSTORMS OVER WESTERN ZONES IN THE
AFTERNOON. STORMS WILL MOVE NORTH TO NORTHEAST AND KICK OUT OF THE
FORECAST FAIRLY QUICKLY IN THE EVENING. SHEAR WOULD BE STRONG
ENOUGH TO PRODUCE SOME STRONG STORMS WITH THE MAIN THREAT BEING
HAIL. WILL HAVE TO WATCH THIS EVENT FOR A POSSIBLE SEVERE WEATHER
DAY. WILL MENTION STRONG STORMS IN THE HWO.
FRIDAY IS A DAY A BIT IN QUESTION AS MODELS DIFFER ON TIMING AND
STRENGTH OF A SHORTWAVE KICKING OFF THE MAIN LOW TO THE WEST. THE
ECMWF WAS STRONGEST AND SLOWEST WITH THIS WAVE AS IT CROSSES THE
FORECAST AREA DURING THE DAY. THE GFS WAS WEAKER AND TAKES IT
ACROSS LATE THURSDAY NIGHT. THE ECMWF WOULD BE WETTER. INHERITED
SCATTERED POPS FOR FRIDAY...BUT IF THE GFS WAS RIGHT...IT WILL BE
DRIER.
DRIER MID LEVEL AIR WILL RUSH IN BEHIND THE SHORTWAVE REGARDLESS
OF THE TIMING. THIS WILL SET UP A MAINLY DRY PERIOD FOR THE
WEEKEND WITH THE MAIN ENERGY STAYING NORTH. HIGH BASED SHOWERS OR
THUNDERSTORMS CAN NOT BE RULED OUT OVER THE WEEKEND THOUGH AS
MODELS KICK DISTURBANCES ACROSS IN SOUTHWEST FLOW. DEWPOINTS
SHOULD BE MUCH LOWER AND THESE SHOWERS WILL NOT CONTAIN A GREAT
DEAL OF PRECIPITATION AND BE MORE WIND PRODUCERS. WILL KEEP POPS
LOW. TEMPERATURES SHOULD SLIGHTLY ABOVE SEASONAL AVERAGES THROUGH
PERIOD. TWH
&&
.AVIATION...
SHOWERS WILL LINGER OVER THE EAST THIS MORNING AND TAPER OFF
THROUGH THE AFTERNOON. THE PRECIPITATION SHOULD STAY MAINLY EAST
OF KMLS AND IMPACT KBHK. FLYING CONDITIONS ARE EXPECTED TO REMAIN
VFR WITH ONLY ISOLATED MVFR CONDITIONS DEVELOPING IN HEAVIER
SHOWERS. THE REST OF THE AREA WILL HAVE A PARTLY CLOUDY SKY WITH
ONLY ISOLATED SHOWERS AND THUNDERSTORMS NEAREST THE MOUNTAINS. TWH
&&
.PRELIMINARY POINT TEMP/POPS...
TDY WED THU FRI SAT SUN MON
-------------------------------------------------------
BIL 067 043/068 047/074 050/075 048/077 051/077 051/073
1/B 12/T 33/T 43/T 22/T 22/T 23/T
LVM 069 039/067 044/065 041/068 040/075 041/076 042/070
1/F 14/T 45/T 43/T 22/T 22/T 23/T
HDN 069 043/070 048/077 050/078 048/079 051/080 051/076
1/B 12/T 33/T 33/T 22/T 22/T 23/T
MLS 059 044/067 047/073 053/075 051/078 055/078 054/076
1/E 11/B 11/N 23/T 22/T 23/T 33/T
4BQ 056 040/065 046/074 052/076 050/079 053/080 052/077
3/W 11/B 11/N 13/T 22/T 23/T 33/T
BHK 050 040/061 043/067 050/070 050/075 053/073 052/073
7/W 21/N 11/N 13/T 22/T 33/T 33/T
SHR 061 037/068 045/075 049/075 046/078 048/079 048/075
1/B 12/T 32/T 23/T 22/T 22/T 23/T
&&
.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...NONE.
WY...NONE.
&&
$$
WEATHER.GOV/BILLINGS
000
FXUS65 KBYZ 210957
AFDBYZ
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BILLINGS MT
357 AM MDT TUE MAY 21 2013
.SHORT TERM...VALID FOR TDY AND WED...
THE WEEKEND RAIN-MAKER WILL CONTINUE EXITING STAGE RIGHT...LEAVING
EASTERLY LOW-LEVEL FLOW IN PLAY THE NEXT SEVERAL DAYS OUT AHEAD OF
A 500-HPA LOW WHICH MOVES INTO THE PACIFIC NORTHWEST. THIS PATTERN
WILL YIELD SEASONABLE TEMPERATURES...AND SOME CHANCE OF STORMS FOR
SOUTH CENTRAL MT...ESPECIALLY LATER ON WED AND WED NIGHT.
TODAY...EARLY-MORNING RADAR TRENDS SUGGEST THAT LIKELY POPS REMAIN
NECESSARY AROUND BAKER AND EKALAKA INTO THE MORNING TO ACCOUNT FOR
RESIDUAL BANDS OF SHOWERS ROTATING WESTWARD INTO THAT AREA. THE 00
UTC GUIDANCE IS CLOSELY CLUSTERED IN ITS QPF OUTPUT...AND IT SHOWS
A SHARP WESTERN GRADIENT TO THE SHOWERS DICTATED BY A WEDGE OF DRY
AIR OVER CENTRAL MT. SURFACE OBSERVATIONS AS OF 09 UTC SUGGEST THE
LOW- AND MID-LEVEL DRYING IS BEGINNING TO INFLUENCE THE MILES CITY
AREA...AND MOST 00 UTC GUIDANCE KEEPS SHOWERS EAST OF THERE TODAY.
EVEN RECENT RAP RUNS AND THE 06 UTC NAM KEEP SHOWERS EAST OF MILES
CITY SO WE WENT WITH A DRY FORECAST THERE THIS MORNING. POPS OVER
THE BAKER AND EKALAKA AREAS DROP BACK TO THE CHANCE CATEGORY AFTER
18 UTC AS WELL SINCE MID-LEVEL FORCING AND MOISTURE ADVECTION WILL
BE WEAKENING BY THAT TIME. OTHERWISE...THE EASTERLY LOW-LEVEL FLOW
WILL BECOME ESTABLISHED OVER MUCH OF THE AREA BY AFTERNOON...WHICH
COULD HELP ASSIST WITH SOME CUMULUS DEVELOPMENT GIVEN THE RESIDUAL
NEAR-SURFACE MOISTURE AFTER WEEKEND RAINFALL. THERE IS JUST ENOUGH
INSTABILITY FORECAST BY THE 00 UTC GUIDANCE OVER THE MOUNTAINS FOR
US TO INCLUDE SLIGHT CHANCES OF CONVECTION AFTER 18 UTC THERE TOO.
HIGHS TODAY WERE LARGELY BASED ON A CONSENSUS OF 00 UTC MOS AS THE
EASTERLY FLOW WILL TEND TO LIMIT MIXING...AND USING BIAS-CORRECTED
FLAVORS OF GUIDANCE SEEMS A BIT DANGEROUS GIVEN NEW SOIL MOISTURE.
TONIGHT...QUIET CONDITIONS SHOULD PREVAIL...AND IN FACT BASED ON A
BLEND OF 00 UTC MOS OUTPUT...LOWS WILL PROBABLY BE BELOW NORMAL IN
MANY SPOTS. WE HAVE A DRY FORECAST IN PLAY AFTER 06 UTC EXCEPT FOR
EXTREME SOUTHEASTERN MT. WE WILL NEED TO BE MINDFULL FOR POTENTIAL
FOG DEVELOPMENT...BUT IT SEEMS THAT NEAR-SURFACE FLOW MIGHT END UP
STAYING JUST STRONG ENOUGH TO PREVENT ITS FORMATION...SO IT IS NOT
IN THE FORECAST AT THIS POINT.
WED INTO WED NIGHT...A BETTER CHANCE OF CONVECTION WILL EXIST OVER
SOUTH CENTRAL MT AS MID-LEVEL LAPSE RATES STEEPEN TO AROUND 7 C/KM
ON STRENGTHENING SOUTHERLY FLOW ALOFT. MOST 00 UTC MODEL SOLUTIONS
GENERATE CONVECTION TOWARD 00 UTC...SO OUR GOING CHANCE-STYLE POPS
ARE CERTAINLY WARRANTED. THE ONLY QUESTION MARK MIGHT BE TIMING OR
EASTWARD EXTENT OF THE WEAK SHORT WAVE THAT GUIDANCE KEYS IN ON TO
YIELD CONVECTION...ESPECIALLY SINCE THE MERIDIONAL FLOW MIGHT TAKE
IT FURTHER WEST THAN EXPECTED. THERE IS PROBABLY A NON-ZERO THREAT
OF SEVERE WEATHER IF STORMS DEVELOP...BUT IT WILL BE KEPT IN CHECK
BY A LACK OF BUOYANCY /MUCAPE 500 J/KG OR LESS/. OVER SOUTHEASTERN
MT...STORM CHANCES ARE MINIMAL OWING TO MID-LEVEL RIDGING. SCHULTZ
.LONG TERM...VALID FOR THU...FRI...SAT...SUN...MON...
MEDIUM RANGE MODELS WERE PRETTY CONSISTENT THROUGH THE PERIOD
WITH SOME TIMING DIFFERENCES OF SHORTWAVES PROGGED TO GET KICKED
OUT OF A DEEP UPPER TROUGH OVER THE WEST MOVING INLAND.
THURSDAY COULD BE AN ACTIVE DAY FOR THUNDERSTORMS...MAINLY
CENTRAL AND WESTERN ZONES. THE DEEP WESTERN TROUGH ADVANCES EAST
SLOWLY AND LOWERS HEIGHTS THROUGH THE DAY. LOW LEVEL EAST TO
SOUTHEAST WINDS WILL ALLOW FOR DEWPOINTS TO HANG AROUND 50 DEGREES
OVER CENTRAL ZONES...WITH SLIGHTLY LOWER VALUES OVER THE WEST.
EFFECTIVE BULK SHEAR INCREASES TO AROUND 35KTS WITH CAPES REACHING
AS HIGH AS 1000 J/KG. STRONG SURFACE CONVERGENCE WITH SHORTWAVE
ENERGY WILL IGNITE THUNDERSTORMS OVER WESTERN ZONES IN THE
AFTERNOON. STORMS WILL MOVE NORTH TO NORTHEAST AND KICK OUT OF THE
FORECAST FAIRLY QUICKLY IN THE EVENING. SHEAR WOULD BE STRONG
ENOUGH TO PRODUCE SOME STRONG STORMS WITH THE MAIN THREAT BEING
HAIL. WILL HAVE TO WATCH THIS EVENT FOR A POSSIBLE SEVERE WEATHER
DAY. WILL MENTION STRONG STORMS IN THE HWO.
FRIDAY IS A DAY A BIT IN QUESTION AS MODELS DIFFER ON TIMING AND
STRENGTH OF A SHORTWAVE KICKING OFF THE MAIN LOW TO THE WEST. THE
ECMWF WAS STRONGEST AND SLOWEST WITH THIS WAVE AS IT CROSSES THE
FORECAST AREA DURING THE DAY. THE GFS WAS WEAKER AND TAKES IT
ACROSS LATE THURSDAY NIGHT. THE ECMWF WOULD BE WETTER. INHERITED
SCATTERED POPS FOR FRIDAY...BUT IF THE GFS WAS RIGHT...IT WILL BE
DRIER.
DRIER MID LEVEL AIR WILL RUSH IN BEHIND THE SHORTWAVE REGARDLESS
OF THE TIMING. THIS WILL SET UP A MAINLY DRY PERIOD FOR THE
WEEKEND WITH THE MAIN ENERGY STAYING NORTH. HIGH BASED SHOWERS OR
THUNDERSTORMS CAN NOT BE RULED OUT OVER THE WEEKEND THOUGH AS
MODELS KICK DISTURBANCES ACROSS IN SOUTHWEST FLOW. DEWPOINTS
SHOULD BE MUCH LOWER AND THESE SHOWERS WILL NOT CONTAIN A GREAT
DEAL OF PRECIPITATION AND BE MORE WIND PRODUCERS. WILL KEEP POPS
LOW. TEMPERATURES SHOULD SLIGHTLY ABOVE SEASONAL AVERAGES THROUGH
PERIOD. TWH
&&
.AVIATION...
SHOWERS WILL LINGER OVER THE EAST THIS MORNING AND TAPER OFF
THROUGH THE AFTERNOON. THE PRECIPITATION SHOULD STAY MAINLY EAST
OF KMLS AND IMPACT KBHK. FLYING CONDITIONS ARE EXPECTED TO REMAIN
VFR WITH ONLY ISOLATED MVFR CONDITIONS DEVELOPING IN HEAVIER
SHOWERS. THE REST OF THE AREA WILL HAVE A PARTLY CLOUDY SKY WITH
ONLY ISOLATED SHOWERS AND THUNDERSTORMS NEAREST THE MOUNTAINS. TWH
&&
.PRELIMINARY POINT TEMP/POPS...
TDY WED THU FRI SAT SUN MON
-------------------------------------------------------
BIL 067 043/068 047/074 050/075 048/077 051/077 051/073
1/B 12/T 33/T 43/T 22/T 22/T 23/T
LVM 069 039/067 044/065 041/068 040/075 041/076 042/070
1/B 14/T 45/T 43/T 22/T 22/T 23/T
HDN 069 043/070 048/077 050/078 048/079 051/080 051/076
1/B 12/T 33/T 33/T 22/T 22/T 23/T
MLS 059 044/067 047/073 053/075 051/078 055/078 054/076
1/E 11/B 11/N 23/T 22/T 23/T 33/T
4BQ 056 040/065 046/074 052/076 050/079 053/080 052/077
3/W 11/B 11/N 13/T 22/T 23/T 33/T
BHK 050 040/061 043/067 050/070 050/075 053/073 052/073
7/W 21/N 11/N 13/T 22/T 33/T 33/T
SHR 061 037/068 045/075 049/075 046/078 048/079 048/075
1/B 12/T 32/T 23/T 22/T 22/T 23/T
&&
.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...NONE.
WY...NONE.
&&
$$
WEATHER.GOV/BILLINGS
000
FXUS65 KBYZ 210316
AFDBYZ
AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE BILLINGS MT
916 PM MDT MON MAY 20 2013
.UPDATE...
A WAVE OF RAIN ASSOCIATED WITH A TROWAL OVER EASTERN MONTANA IS
MAKING ITS WAY INTO THE CENTRAL ZONES THIS EVENING AND MAY EVEN
GET INTO THE BILLINGS VICINITY. ANOTHER WAVE IS ALSO MOVING ACROSS
THE DAKOTA BORDER INTO OUR FAR EASTERN ZONES SUCH AS CARTER AND
FALLON COUNTIES. MUCH OF THIS PRECIPITATION IS EXPECTED TO
DIMINISH AFTER MIDNIGHT AS THE GFS AND NAM HAVE INDICATED
WEAKENING ISENTROPIC LIFT ACROSS THE REGION...CONFIRMED BY RECENT
RAP MODEL ANALYSIS. IN THE FAR WEST...SOME ISOLATED SHOWERS MAY
HANG ON AND HUG THE HIGHER TERRAIN FOR AWHILE BEFORE DISSIPATING.
FOR THIS UPDATE MADE CHANGES TO OVERNIGHT POPS BASED ON RADAR
TRENDS AND RAP DATA. BT
&&
.SHORT TERM...VALID FOR TUE AND WED...
LARGE UPPER LOW CONTINUES TO HOLD FIRM ACROSS THE EASTERN DAKOTAS
THIS AFTERNOON. LARGE AREA OF WRAP AROUND RAIN AS SHOWN BY
SATELLITE AND RADAR WILL MOVE WEST AND SOUTHWEST INTO EASTERN
MONTANA FOR THE REMAINDER OF THE AFTERNOON AND THROUGH THE EVENING
HOURS. RADAR SHOWING LIGHT TO OCCASIONALLY MODERATE RAIN FALLING
FROM ABOUT ROSEBUD COUNTY EASTWARD. SOME BREAKS IN SUN WEST OF
THIS AREA HAVE RESULTED IN NUMEROUS CONVECTIVE SHOWERS WITH
ISOLATED LIGHTNING STRIKES. HAVE ADDED AN ISOLATED THUNDERSTORM TO
THE FORECAST FROM YELLOWSTONE COUNTY WESTWARD THROUGH MID EVENING
WHEN THE ATMOSPHERE SHOULD BE STABILIZING SHORTLY AFTER SUNSET.
WILL KEEP A CHANCE FOR SHOWERS AND AN ISOLATED THUNDERSTORM
THROUGH THE EVENING HOURS. RAINFALL AMOUNTS AT MILES CITY AND
BAKER SINCE MIDNIGHT HAVE BEEN SIGNIFICANT...ESPECIALLY ON AN
HOURLY BASIS. HAVE NOT HAD ANY REPORTS OF SIGNIFICANT FLOODING IN
THE BURN SCAR AREAS SO HAVE DECIDED TO CANCEL THE FLASH FLOOD
WATCH WITH THIS FORECAST ISSUANCE. AS FOR THE FLOOD ADVISORY FOR
PORTIONS OF YELLOWSTONE AND BIG HORN COUNTIES...HAVE RECENTLY
CANCELLED THAT AS WELL AS REPORTS ALONG PRYOR CREEK INDICATE VERY
LITTLE RISING OF THE CREEK AND HAVE NOT HAD ANY REPORTS OF
SIGNIFICANT FLOODING FOR THIS AREA AS WELL.
THE UPPER LOW WILL SLOWLY SHIFT EAST TONIGHT AND ESPECIALLY
TUESDAY AND BEGIN TO LOSE ITS ORGANIZATION AS WELL. WILL KEEP
LIKELY POPS FOR CUSTER AND POWDER RIVER COUNTIES EASTWARD TONIGHT
WITH LIKELY POPS TUESDAY ALONG THE DAKOTA BORDER WITH CHANCE POPS
CUSTER AND POWDER RIVER COUNTIES. FURTHER WEST...CONDITIONS LOOK
TO DRY OUT AND NOT EXPECTING AND SHOWER ACTIVITY DURING THE DAY
TUESDAY.
WEDNESDAY...PRECIP CHANCES INCREASE ONCE AGAIN BY AFTERNOON AND
INTO WEDNESDAY NIGHT. A LARGE UPPER LOW MOVES ONTO THE PACIFIC
NORTHWEST COAST AND REMAINS NEARLY STATIONARY THROUGH AT LEAST
THURSDAY. UNLIKE THIS LAST LOW WHICH WAS SLOW MOVING ACROSS
NORTHERN WYOMING INTO THE DAKOTAS THIS LOW WILL PUT OUR FORECAST
AREA UNDER A WARM SOUTH TO SOUTHWEST FLOW ALOFT. PIECES OF ENERGY
WILL ROTATE AROUND THIS LOW AND THIS COMBINED WITH A DIFFLUENT FLOW
ALOFT WILL BRING INCREASING CHANCES FOR THUNDERSTORMS. AT THIS
TIME STRONGEST DYNAMICS LOOK TO REMAIN ACROSS WESTERN MONTANA AND
IDAHO WEDNESDAY INTO WEDNESDAY NIGHT. HIGH CHANCES FOR
THUNDERSTORMS WILL EXIST FROM ABOUT BILLINGS WESTWARD WEDNESDAY
AFTERNOON AND EVENING. DYNAMICS WILL BE IN PLACE FOR POSSIBLE
SEVERE THUNDERSTORMS IN PART THANKS TO THIS LAST STORM SYSTEM
WHICH HAS PROVIDED FOR A MOIST GROUND RESULTING IN HIGHER
DEWPOINTS. FORECAST AREA SHOULD ALSO HAVE AN EASTERLY SURFACE FLOW
ALONG WITH SOME WIND SHEAR AIDING IN SEVERE INGREDIENTS. SO THE
POTENTIAL EXISTS WEDNESDAY THROUGH THE END OF THE WEEK FOR SOME
SEVERE THUNDERSTORMS. HOOLEY
.LONG TERM...VALID FOR THU...FRI...SAT...SUN...MON...
HEIGHTS LOWER THURSDAY AS THE UPPER LEVEL TROUGH MOVES SLOWLY
EASTWARD. DIFFLUENT FLOW INCREASES WITH INCREASING SHEAR. LOW
LEVEL SOUTHEASTERLY WINDS WILL KEEP DEWPOINTS IN THE UPPER 40S TO
LOW 50S. CAPE VALUES LOOK TO BE ABOVE 1000 J/KG ACROSS PORTIONS
OF THE WEST AND CENTRAL...WITH EFFECTIVE BULK SHEAR VALUES
APPROACHING 40 KTS...SO STRONG TO SEVERE STORMS WITH GUSTY WINDS
AND LARGE HAIL ARE POSSIBLE. DID NOT MENTION SEVERE IN THE
FORECAST. WILL LET THE MID SHIFT TAKE ANOTHER LOOK.
MODELS SHOW ANOTHER WAVE MOVING THROUGH THE REGION IN SW
FLOW FRIDAY AFTERNOON/EVENING. CAPE VALUES AGAIN LOOK TO EXCEED
500 J/KG ACROSS PORTIONS OF THE CENTRAL AND EAST...WITH SURFACE
DEWPOINTS APPROACHING 50 AND BULK SHEAR VALUES OVER 30 KTS...SO
STRONG THUNDERSTORMS ARE AGAIN POSSIBLE...ESPECIALLY ACROSS THE
EASTERN HALF OF THE CWA.
MODELS BEGIN TO DIFFER A BIT IN THEIR SOLUTIONS SATURDAY THROUGH
MONDAY. THE ECMWF BUILDS SOME UPPER LEVEL RIDGING INTO THE REGION
SATURDAY AHEAD OF THE UPPER LEVEL LOW...WHICH IS PROGGED TO STALL
OVER THE PACIFIC NW. THIS WOULD LEAD TO A DRIER FORECAST THAN THE
GFS...WHICH KEEPS US IN MORE SW FLOW AND SHORTWAVE ACTIVITY. NOT
TOO CONFIDENT ABOUT WHAT WILL HAPPEN SATURDAY...SO BASICALLY
BROADBRUSHED THE CWA IN LOW POPS.
SEVERAL STRONGER PIECES OF ENERGY ARE PROGGED BY BOTH THE GFS AND
ECMWF TO SWING THROUGH THE REGION SUNDAY AND MONDAY. THOUGH THERE
ARE MODEL DIFFERENCES IN BOTH STRENGTH AND TIMING...IT DOES LOOK
LIKE THERE MAY BE SOME STRONG UPPER LEVEL DIFFLUENCE AS WELL AS
INCREASED SE LOW LEVEL FLOW BRINGING IN ADDITIONAL MOISTURE. CAPE
AND AND EFFECTIVE BULK SHEAR VALUES ARE SUPPORTIVE OF STRONG
STORMS...ESPECIALLY DURING THE AFTERNOON AND EVENING HOURS...SO I
KEPT AT LEAST A SLIGHT CHANCE OF THUNDERSTORMS IN THE FORECAST
BOTH SUNDAY AND MONDAY.
AS FOR TEMPS...LOOK FOR A WARMING TREND THROUGH THE EXTENDED.
TEMPS LOOKED A FEW DEGREES TOO COOL...SO I RAISED THEM A BIT. STC
&&
.AVIATION...
SLOW MOVING UPPER LOW PRESSURE OVER THE NORTHERN PLAINS WILL
CONTINUE TO SPREAD LIGHT RAIN SHOWERS INTO OUR AREA...MAINLY EAST
OF KBIL...TONIGHT AND TUESDAY. AREAS OF MVFR CONDITIONS WILL
IMPACT KMLS AND KBHK. TO THE WEST INCLUDING KLVM...SCATTERED
SHOWERS AND TSTMS ARE DIMINISHING AND SHOULD END BY 06Z. VFR WILL
PREVAIL IN THIS AREA THOUGH TUESDAY...BUT CANNOT DISCOUNT
LOCALIZED FOG NEAR KLVM LATE TONIGHT. EAST WINDS WILL INCREASE ON
TUESDAY WITH GUSTS OF 15-25 KTS BY AFTERNOON. JKL
&&
.PRELIMINARY POINT TEMP/POPS...
TUE WED THU FRI SAT SUN MON
-----------------------------------------------------------
BIL 044/066 042/068 049/073 050/075 048/077 051/077 051/073
41/B 12/T 33/T 43/T 32/T 22/T 22/T
LVM 037/069 039/066 042/067 041/068 040/075 041/076 042/070
31/B 14/T 44/T 43/T 32/T 22/T 22/T
HDN 045/069 044/070 049/077 050/078 048/079 051/080 051/076
51/B 12/T 33/T 33/T 32/T 22/T 22/T
MLS 045/058 043/066 048/073 053/075 051/078 055/078 054/076
43/W 21/B 21/N 33/T 32/T 23/T 33/T
4BQ 044/060 043/066 048/074 052/076 050/079 053/080 052/077
64/W 21/B 21/N 23/T 32/T 23/T 33/T
BHK 041/050 040/060 045/067 050/070 050/075 053/073 052/073
+6/W 22/T 11/N 33/T 33/T 33/T 34/T
SHR 040/061 038/067 046/076 049/075 046/078 048/079 048/075
61/B 12/T 32/T 33/T 32/T 22/T 22/T
&&
.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...NONE.
WY...NONE.
&&
$$
WEATHER.GOV/BILLINGS
000
FXUS65 KBYZ 202107
AFDBYZ
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BILLINGS MT
307 PM MDT MON MAY 20 2013
.SHORT TERM...VALID FOR TUE AND WED...
LARGE UPPER LOW CONTINUES TO HOLD FIRM ACROSS THE EASTERN DAKOTAS
THIS AFTERNOON. AREA OF WRAP AROUND RAIN AS SHOWN BY SATELLITE
AND RADAR WILL MOVE WEST AND SOUTHWEST INTO EASTERN MONTANA FOR
THE REMAINDER OF THE AFTERNOON AND THROUGH THE EVENING HOURS.
RADAR SHOWING LIGHT TO OCCASIONALLY MODERATE RAIN FALLING FROM
ABOUT ROSEBUD COUNTY EASTWARD. SOME BREAKS IN SUN WEST OF THIS
AREA HAVE RESULTED IN NUMEROUS CONVECTIVE SHOWERS WITH ISOLATED
LIGHTNING STRIKES. HAVE ADDED AN ISOLATED THUNDERSTORM TO THE
FORECAST FROM YELLOWSTONE COUNTY WESTWARD THROUGH MID EVENING WHEN
THE ATMOSPHERE SHOULD BE STABILIZING SHORTLY AFTER SUNSET. WILL
KEEP A CHANCE FOR SHOWERS AND AN ISOLATED THUNDERSTORM THROUGH THE
EVENING HOURS. RAINFALL AMOUNTS AT MILES CITY AND BAKER SINCE
MIDNIGHT HAVE BEEN SIGNIFICANT...ESPECIALLY ON AN HOURLY BASIS.
HAVE NOT HAD ANY REPORTS OF SIGNIFICANT FLOODING IN THE BURN SCAR
AREAS SO HAVE DECIDED TO CANCEL THE FLASH FLOOD WATCH WITH THIS
FORECAST ISSUANCE. AS FOR THE FLOOD ADVISORY FOR PORTIONS OF
YELLOWSTONE AND BIG HORN COUNTIES...HAVE RECENTLY CANCELLED THAT
AS WELL AS REPORTS ALONG PRYOR CREEK INDICATE VERY LITTLE RISING
OF THE CREEK AND HAVE NOT HAD ANY REPORTS OF SIGNIFICANT FLOODING
FOR THIS AREA AS WELL.
THE UPPER LOW WILL SLOWLY SHIFT EAST TONIGHT AND ESPECIALLY
TUESDAY AND BEGIN TO LOSE ITS ORGANIZATION AS WELL. WILL KEEP
LIKELY POPS FOR CUSTER AND POWDER RIVER COUNTIES EASTWARD TONIGHT
WITH LIKELY POPS TUESDAY ALONG THE DAKOTA BORDER WITH CHANCE POPS
CUSTER AND POWDER RIVER COUNTIES. FURTHER WEST...CONDITIONS LOOK
TO DRY OUT AND NOT EXPECTING AND SHOWER ACTIVITY DURING THE DAY
TUESDAY.
WEDNESDAY...PRECIP CHANCES INCREASE ONCE AGAIN BY AFTERNOON AND
INTO WEDNESDAY NIGHT. A LARGE UPPER LOW MOVES ONTO THE PACIFIC
NORTHWEST COAST AND REMAINS NEARLY STATIONARY THROUGH AT LEAST
THURSDAY. UNLIKE THIS LAST LOW WHICH WAS SLOW MOVING ACROSS
NORTHERN WYOMING INTO THE DAKOTAS THIS LOW WILL PUT OUR FORECAST
AREA UNDER A WARM SOUTH TO SOUTHWEST FLOW ALOFT. PIECES OF ENERGY
WILL ROTATE AROUND THIS LOW AND THIS COMBINED WITH A DIFFLUENT
FLOW ALOFT WILL BRING INCREASING CHANCES FOR THUNDERSTORMS. AT
THIS TIME...STRONGEST DYNAMICS LOOK TO REMAIN ACROSS WESTERN
MONTANA AND IDAHO WEDNESDAY INTO WEDNESDAY NIGHT. HIGH CHANCES FOR
THUNDERSTORMS WILL EXIST FROM ABOUT BILLINGS WESTWARD WEDNESDAY
AFTERNOON AND EVENING. DYNAMICS WILL BE IN PLACE FOR POSSIBLE
SEVERE THUNDERSTORMS IN PART THANKS TO THIS LAST STORM SYSTEM
WHICH HAS PROVIDED FOR A MOIST GROUND RESULTING IN HIGHER
DEWPOINTS. FORECAST AREA SHOULD ALSO HAVE AN EASTERLY SURFACE FLOW
ALONG WITH SOME WIND SHEAR AIDING IN SEVERE INGREDIENTS. SO THE
POTENTIAL EXISTS WEDNESDAY THROUGH THE END OF THE WEEK FOR SOME
SEVERE THUNDERSTORMS. HOOLEY
.LONG TERM...VALID FOR THU...FRI...SAT...SUN...MON...
HEIGHTS LOWER THURSDAY AS THE UPPER LEVEL TROUGH MOVES SLOWLY
EASTWARD. DIFFLUENT FLOW INCREASES WITH INCREASING SHEAR. LOW
LEVEL SOUTHEASTERLY WINDS WILL KEEP DEWPOINTS IN THE UPPER 40S TO
LOW 50S. CAPE VALUES LOOK TO BE ABOVE 1000 J/KG ACROSS PORTIONS
OF THE WEST AND CENTRAL...WITH EFFECTIVE BULK SHEAR VALUES
APPROACHING 40 KTS...SO STRONG TO SEVERE STORMS WITH GUSTY WINDS
AND LARGE HAIL ARE POSSIBLE. DID NOT MENTION SEVERE IN THE
FORECAST. WILL LET THE MID SHIFT TAKE ANOTHER LOOK.
MODELS SHOW ANOTHER WAVE MOVING THROUGH THE REGION IN SW
FLOW FRIDAY AFTERNOON/EVENING. CAPE VALUES AGAIN LOOK TO EXCEED
500 J/KG ACROSS PORTIONS OF THE CENTRAL AND EAST...WITH SURFACE
DEWPOINTS APPROACHING 50 AND BULK SHEAR VALUES OVER 30 KTS...SO
STRONG THUNDERSTORMS ARE AGAIN POSSIBLE...ESPECIALLY ACROSS THE
EASTERN HALF OF THE CWA.
MODELS BEGIN TO DIFFER A BIT IN THEIR SOLUTIONS SATURDAY THROUGH
MONDAY. THE ECMWF BUILDS SOME UPPER LEVEL RIDGING INTO THE REGION
SATURDAY AHEAD OF THE UPPER LEVEL LOW...WHICH IS PROGGED TO STALL
OVER THE PACIFIC NW. THIS WOULD LEAD TO A DRIER FORECAST THAN THE
GFS...WHICH KEEPS US IN MORE SW FLOW AND SHORTWAVE ACTIVITY. NOT
TOO CONFIDENT ABOUT WHAT WILL HAPPEN SATURDAY...SO BASICALLY
BROADBRUSHED THE CWA IN LOW POPS.
SEVERAL STRONGER PIECES OF ENERGY ARE PROGGED BY BOTH THE GFS AND
ECMWF TO SWING THROUGH THE REGION SUNDAY AND MONDAY. THOUGH THERE
ARE MODEL DIFFERENCES IN BOTH STRENGTH AND TIMING...IT DOES LOOK
LIKE THERE MAY BE SOME STRONG UPPER LEVEL DIFFLUENCE AS WELL AS
INCREASED SE LOW LEVEL FLOW BRINGING IN ADDITIONAL MOISTURE. CAPE
AND AND EFFECTIVE BULK SHEAR VALUES ARE SUPPORTIVE OF STRONG
STORMS...ESPECIALLY DURING THE AFTERNOON AND EVENING HOURS...SO I
KEPT AT LEAST A SLIGHT CHANCE OF THUNDERSTORMS IN THE FORECAST
BOTH SUNDAY AND MONDAY.
AS FOR TEMPS...LOOK FOR A WARMING TREND THROUGH THE EXTENDED.
TEMPS LOOKED A FEW DEGREES TOO COOL...SO I RAISED THEM A BIT. STC
&&
.AVIATION...
ACROSS THE EAST...RAIN/RAIN SHOWERS CAN BE EXPECTED TO CONTINUE
INTO TONIGHT...WITH CONDITIONS OCCASIONALLY LOWERING TO MVFR AT
TERMINALS SUCH AS KBHK AND KMLS. ACROSS THE WEST...RAIN SHOWERS
AND A FEW THUNDERSTORMS WILL BE POSSIBLE THROUGH EARLY THIS
EVENING...INCLUDING NEAR KBIL AND KLVM. A DECREASING TREND IN
AREAL COVERAGE OF PRECIPITATION WILL OCCUR OVERNIGHT.
NORTH TO NORTHWEST WINDS GUSTS GREATER THAN 35 MPH CAN BE
EXPECTED AT SHERIDAN...MILES CITY AND BAKER THROUGH EARLY THIS
EVENING...THEN WINDS GRADUALLY DECREASE OVERNIGHT. MOUNTAIN
OBSCURATION WILL BE POSSIBLE THROUGH TUESDAY MORNING. STC
&&
.PRELIMINARY POINT TEMP/POPS...
TUE WED THU FRI SAT SUN MON
-----------------------------------------------------------
BIL 044/066 042/068 049/073 050/075 048/077 051/077 051/073
31/B 12/T 33/T 43/T 32/T 22/T 22/T
LVM 037/069 039/066 042/067 041/068 040/075 041/076 042/070
21/B 14/T 44/T 43/T 32/T 22/T 22/T
HDN 045/069 044/070 049/077 050/078 048/079 051/080 051/076
41/B 12/T 33/T 33/T 32/T 22/T 22/T
MLS 045/058 043/066 048/073 053/075 051/078 055/078 054/076
73/W 21/B 21/N 33/T 32/T 23/T 33/T
4BQ 044/060 043/066 048/074 052/076 050/079 053/080 052/077
64/W 21/B 21/N 23/T 32/T 23/T 33/T
BHK 041/050 040/060 045/067 050/070 050/075 053/073 052/073
+6/W 22/T 11/N 33/T 33/T 33/T 34/T
SHR 040/061 038/067 046/076 049/075 046/078 048/079 048/075
41/B 12/T 32/T 33/T 32/T 22/T 22/T
&&
.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...NONE.
WY...NONE.
&&
$$
WEATHER.GOV/BILLINGS
000
FXUS65 KBYZ 201550
AFDBYZ
AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE BILLINGS MT
950 AM MDT MON MAY 20 2013
.UPDATE...
LARGE UPPER LOW CONTINUES TO BE LOCATED OVER THE EASTERN DAKOTAS
AND IS EXPECTED TO REMAIN STATIONARY THROUGH THE DAY. MOISTURE
CONTINUES TO WRAP AROUND THE LOW AND PUSH WESTWARD INTO THE
EASTERN PORTIONS OF MONTANA. WILL KEEP LIKELY TO CATEGORICAL POPS
FROM ROSEBUD COUNTY EASTWARD TODAY WITH SCATTERED POPS ELSEWHERE.
RAINFALL AMOUNTS SHOULD BE LESS THAN OVER THE WEEKEND WITH AREAS
ACROSS THE EAST PICKING UP AN ADDITIONAL .20 TO .40 INCHES TODAY
SO RATES SHOULD NOT BE AS HIGH EITHER. WILL CONTINUE TO MONITOR
RIVERS AND CREEKS FOR POSSIBLE STATEMENTS BUT AT THIS TIME THERE
HAVE BEEN NO REPORTS OF SIGNIFICANT FLOODING. WILL CONTINUE WITH
THE FLASH FLOOD WATCH FOR THE BURN AREAS ACROSS THE EAST BUT THIS
MAY BE CANCELLED LATER THIS AFTERNOON. MADE SOME MINOR ADJUSTMENTS
TO POPS AND TEMPS. ONE OTHER ISSUE TO WATCH TODAY WILL BE POSSIBLE
HIGH WINDS FOR THE SHERIDAN AREA GIVEN TIGHT PRESSURE GRADIENT
ACROSS THAT AREA. SOME MODELS SHOW SUSTAINED WINDS NEAR 40 MPH
TODAY. FORECAST HAS THIS COVERED WELL WITH 25 TO 35 MPH WITH GUSTS
TO 50 MPH. IF WINDS DO HIT WARNING CRITERIA IT SHOULD BE JUST FOR
A SHORT PERIOD OF TIME. HOOLEY
&&
.SHORT TERM...VALID FOR TDY AND TUE...
ONE OF THE BEST RAIN EVENTS THAT PARTS OF THE AREA HAS EXPERIENCED
IN TWO YEARS IS NOT OVER YET...BUT IT WILL BEGIN WINDING DOWN OVER
THE NEXT 12 TO 18 HOURS. IN FACT...SOME PLACES LIKE BILLINGS MIGHT
HAVE TO DEPEND ON SCATTERED SHOWERS TO GET MUCH MORE RAINFALL.
TODAY...WE EXPECT TWO DISTINCT AREAS OF PRECIPITATION...ONE DRIVEN
BY DYNAMIC FORCING IN SOUTHEASTERN MT...AND A SECOND ONE CAUSED BY
UPSLOPE FLOW AND WEAK INSTABILITY IN SOUTH CENTRAL MT. THE SHOWERS
WHICH PUSHED WESTWARD OUT OF ND AND INTO SOUTHEASTERN MT OVERNIGHT
HAVE BEEN OCCURRING IN AN AREA OF MODERATE MID-LEVEL FRONTOGENESIS
AND 500-300 HPA Q-VECTOR CONVERGENCE WITH THETA-E ADVECTION ON THE
NORTHWEST SIDE OF A 700-HPA LOW. THE 00 UTC MODELS ALL SUGGEST THE
Q-VECTOR CONVERGENCE WILL PERSIST IN SOUTHEASTERN MT TODAY...WHILE
THE FRONTOGENESIS SIGNATURE WEAKENS. THAT SHOULD RESULT IN LIGHTER
PRECIPITATION AFTER 18 UTC...AND POSSIBLY EVEN SOME BREAKS IN RAIN
SINCE SEVERAL HIGH-RESOLUTION MODELS SUGGEST THE FORCING BREAKS UP
INTO WAVES REGULATED BY MID-LEVEL THETA-E ADVECTION. TRENDS IN THE
RADAR DATA EARLY THIS MORNING ALREADY SHOW THIS OCCURRING. WE KEPT
POPS IN THE 90 TO 100 PERCENT RANGE AS FAR WEST AS HYSHAM AND LAME
DEER THROUGH THE DAY GIVEN TIGHT CLUSTERING OF THE QPF FROM THE 00
UTC MODELS...EVEN THOUGH IT MAY NOT BE A PERSISTENT RAIN. OVER THE
SOUTH CENTRAL PART OF MT...OUTSIDE OF IMMEDIATE UPSLOPE AREAS...WE
DECIDED TO DROP POPS INTO THE CHANCE RANGE AS PRECIPITATION MAY BE
MORE CONVECTIVE. BILLINGS MAY END UP RIGHT IN BETWEEN BOTH REGIMES
AND SO WE PUSHED POPS DOWN TO AROUND 40 PERCENT IN THE CITY TODAY.
GIVEN WEAK LOW-LEVEL INSTABILITY IN FORECAST SOUNDINGS AND THUNDER
PROBABILITIES OF 10 TO 30 PERCENT FROM THE 03 UTC SREF ACROSS PART
OF SOUTH CENTRAL MT...WE ALSO MENTIONED ISOLATED STORMS FROM 18 TO
03 UTC. ONE OTHER ITEM OF NOTE TODAY WILL BE STRONG WINDS IN PARTS
OF THE AREA...ESPECIALLY AROUND SHERIDAN...WHERE WE COULD BE RIGHT
AT THE CUSP OF HIGH WIND WARNING CRITERIA WITH REGARD TO SUSTAINED
SPEEDS AT TIMES. MOS GUIDANCE SUGGESTS WINDS JUST UNDER THE 40 MPH
HEADLINE CRITERIA...SO WE HELD OFF ON A WARNING FOR NOW.
WHERE HYDROLOGY ISSUES ARE CONCERNED...MUSSELSHELL COUNTY HAS BEEN
DROPPED FROM THE FLASH FLOOD WATCH FOR BURN SCAR AREAS SINCE WE DO
NOT EXPECT MUCH MORE RAIN THERE. WE LEFT THE REST OF THE WATCH FOR
NOW...BUT IT MAY BE CANCELLED LATER TODAY OR THIS EVENING.
TONIGHT...A DRYING TREND WILL CONTINUE...AND IN FACT MOST OF SOUTH
CENTRAL MT WILL BE PRECIPITATION-FREE BY 06 UTC AS CONVECTION DIES
OUT. PRECIPITATION IN SOUTHEASTERN MT WILL ALSO SLOWLY PULL OUT AS
FORCING WEAKENS AND HEADS EAST...BUT THE 00 UTC GUIDANCE SUPPORTED
A CONTINUATION OF CATEGORICAL POPS IN EXTREME SOUTHEASTERN MT NEAR
BAKER AND EKALAKA THROUGH THE NIGHT. ADMITTEDLY...THOSE POPS COULD
BE A BIT HIGH...ESPECIALLY SINCE THERE IS A SUBTLE TREND IN THE 00
UTC MODELS TO PULL THE 700- AND 500-HPA LOWS EAST SLIGHTLY FASTER.
TUE...WE LEFT SOME CHANCE POPS IN PLACE OVER SOUTHEASTERN MT...BUT
IF THE NEXT MODEL CYCLE OR TWO CONTINUES ON A SLIGHTLY FASTER EXIT
OF THE PRECIPITATION...THOSE POPS MAY BE REDUCED FURTHER. SOME SUN
WILL LEAD TO A WARMER DAY...ESPECIALLY IN SOUTH CENTRAL MT. WE MAY
HAVE SOME AFTERNOON CUMULUS BUILDUPS THOUGH WITH RESIDUAL MOISTURE
IN THE BOUNDARY LAYER FROM THE RECENT RAIN. WE COULD ALSO HAVE FOG
ISSUES AT SOME POINT IN THE NEXT FEW DAYS THANKS TO THAT ENHANCED
MOISTURE. SCHULTZ
.LONG TERM...VALID FOR WED...THU...FRI...SAT...SUN...
FOCUS OF ATTENTION ON THE EXTENDED PACKAGE WILL TURN TO A DEEP
WESTERN TROUGH PROGGED TO MOVE INLAND ON TUESDAY. INCREASING
SOUTHWEST FLOW ALOFT WILL MOVE INTO WESTERN SECTIONS WEDNESDAY.
LINGERING EASTERLY FLOW AT THE LOW LEVELS AND SOME MID LEVEL
MOISTURE WILL PRODUCE WEAK CAPE AND SHEAR. INCREASING DIFFLUENT
FLOW SHOULD TRIGGER SCATTERED SHOWERS AND THUNDERSTORMS OVER THE
WEST...SO MAINTAINED SCATTERED POPS FROM BILLINGS WESTWARD.
HEIGHTS LOWER THURSDAY AS THE TROUGH MOVES SLOWLY EASTWARD.
DIFFLUENT FLOW INCREASES WITH INCREASING SHEAR. LOW LEVEL EASTERLY
WINDS WILL KEEP DEWPOINTS IN THE UPPER 40S TO AROUND 50. LOOKS
LIKE A BETTER CHANCE OF CONVECTION FOR THE WESTERN HALF OF THE
AREA. CAPE WAS NOT TREMENDOUS...BUT WITH INCREASING SHEAR...COULD
HAVE SOME STRONG STORMS. WILL HAVE TO MONITOR THIS AS THE DAY
APPROACHES.
MODELS DIFFER A BIT ON HOW FRIDAY PANS OUT. THE ECMWF WANTS TO
KICK A STRONG SHORTWAVE ACROSS THE AREA. THE GFS WAS FASTER WITH
IT AND SENDS IT THROUGH THURSDAY NIGHT AND FRIDAY MORNING. THE
ECMWF WOULD PRODUCE STRONGER LIFT AND PROVIDE A MUCH BETTER CHANCE
FOR SHOWERS AND THUNDERSTORMS. WILL KEEP SCATTERED POPS FOR THE
WESTERN HALF OF THE AREA. IF THE GFS PANS OUT...FRIDAY WOULD BE
MAINLY DRY AS MUCH DRIER MID LEVEL AIR PULLS ACROSS THE AREA
BEHIND THE SHORTWAVE. ONCE THE SHORTWAVE MOVES ACROSS...DRIER MID
LEVEL AIR WILL SWEEP THROUGH AND LIMIT THE CHANCE OF CONVECTION AS
ENERGY STAYS NORTH. THIS DRIER AIR SHOULD ALLOW FOR WARMER
TEMPERATURES FOR THE END OF THE WEEK INTO THE WEEKEND BUT NOTHING
TREMENDOUSLY WARM WITH SEASONAL HEIGHTS. TWH
&&
.AVIATION...
RAIN CAN BE EXPECTED TO CONTINUE EAST OF BILLINGS TODAY WITH
CONDITIONS OCCASIONALLY LOWERING TO MVFR. AREAS ALONG THE EAST
SLOPES FROM NYE TO RED LODGE CAN ALSO EXPECT PERSISTENT SHOWERS
TODAY. THIS WILL CAUSE MOUNTAIN OBSCURATIONS. THE REST OF THE AREA
WILL RECEIVE SCATTERED SHOWERS WITH A DECREASING TREND IN
COVERAGE THIS AFTERNOON. A FEW THUNDERSTORMS ARE POSSIBLE ACROSS
THE WEST.
NORTH TO NORTHWEST WINDS WILL BE STRONG TODAY FROM BILLINGS AND
SHERIDAN EASTWARD. GUSTS GREATER THAN 35 MPH CAN BE EXPECTED AT
SHERIDAN...MILES CITY AND BAKER. THE WINDS AND SHOWERS WILL
DECREASE THIS EVENING. STC
&&
.PRELIMINARY POINT TEMP/POPS...
TDY TUE WED THU FRI SAT SUN
-------------------------------------------------------
BIL 061 044/068 043/068 049/071 049/075 050/075 050/074
4/W 31/B 02/T 42/T 42/T 22/T 22/T
LVM 060 038/069 040/066 040/065 041/068 042/069 041/068
7/T 41/B 14/T 44/T 43/T 32/T 22/T
HDN 059 045/069 044/070 049/073 048/078 050/077 050/076
6/W 41/B 02/T 32/T 32/T 22/T 22/T
MLS 056 046/063 044/066 050/070 050/075 052/076 053/076
+/R 73/W 12/T 22/T 22/T 22/T 22/T
4BQ 051 044/060 043/066 048/070 049/076 051/076 052/077
+/W 74/W 22/T 21/N 22/T 22/T 22/T
BHK 051 042/056 041/062 047/066 048/070 051/074 052/073
+/R +5/W 22/T 21/N 22/T 22/T 33/T
SHR 053 041/063 038/067 046/071 046/075 048/075 048/074
7/W 41/N 12/T 32/T 32/T 22/T 22/T
&&
.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...FLASH FLOOD WATCH IN EFFECT THROUGH LATE TONIGHT FOR ZONES
30-31-36>38-57-58.
WY...NONE.
&&
$$
WEATHER.GOV/BILLINGS
000
FXUS65 KBYZ 200918
AFDBYZ
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BILLINGS MT
318 AM MDT MON MAY 20 2013
.SHORT TERM...VALID FOR TDY AND TUE...
ONE OF THE BEST RAIN EVENTS THAT PARTS OF THE AREA HAS EXPERIENCED
IN TWO YEARS IS NOT OVER YET...BUT IT WILL BEGIN WINDING DOWN OVER
THE NEXT 12 TO 18 HOURS. IN FACT...SOME PLACES LIKE BILLINGS MIGHT
HAVE TO DEPEND ON SCATTERED SHOWERS TO GET MUCH MORE RAINFALL.
TODAY...WE EXPECT TWO DISTINCT AREAS OF PRECIPITATION...ONE DRIVEN
BY DYNAMIC FORCING IN SOUTHEASTERN MT...AND A SECOND ONE CAUSED BY
UPSLOPE FLOW AND WEAK INSTABILITY IN SOUTH CENTRAL MT. THE SHOWERS
WHICH PUSHED WESTWARD OUT OF ND AND INTO SOUTHEASTERN MT OVERNIGHT
HAVE BEEN OCCURRING IN AN AREA OF MODERATE MID-LEVEL FRONTOGENESIS
AND 500-300 HPA Q-VECTOR CONVERGENCE WITH THETA-E ADVECTION ON THE
NORTHWEST SIDE OF A 700-HPA LOW. THE 00 UTC MODELS ALL SUGGEST THE
Q-VECTOR CONVERGENCE WILL PERSIST IN SOUTHEASTERN MT TODAY...WHILE
THE FRONTOGENESIS SIGNATURE WEAKENS. THAT SHOULD RESULT IN LIGHTER
PRECIPITATION AFTER 18 UTC...AND POSSIBLY EVEN SOME BREAKS IN RAIN
SINCE SEVERAL HIGH-RESOLUTION MODELS SUGGEST THE FORCING BREAKS UP
INTO WAVES REGULATED BY MID-LEVEL THETA-E ADVECTION. TRENDS IN THE
RADAR DATA EARLY THIS MORNING ALREADY SHOW THIS OCCURRING. WE KEPT
POPS IN THE 90 TO 100 PERCENT RANGE AS FAR WEST AS HYSHAM AND LAME
DEER THROUGH THE DAY GIVEN TIGHT CLUSTERING OF THE QPF FROM THE 00
UTC MODELS...EVEN THOUGH IT MAY NOT BE A PERSISTENT RAIN. OVER THE
SOUTH CENTRAL PART OF MT...OUTSIDE OF IMMEDIATE UPSLOPE AREAS...WE
DECIDED TO DROP POPS INTO THE CHANCE RANGE AS PRECIPITATION MAY BE
MORE CONVECTIVE. BILLINGS MAY END UP RIGHT IN BETWEEN BOTH REGIMES
AND SO WE PUSHED POPS DOWN TO AROUND 40 PERCENT IN THE CITY TODAY.
GIVEN WEAK LOW-LEVEL INSTABILITY IN FORECAST SOUNDINGS AND THUNDER
PROBABILITIES OF 10 TO 30 PERCENT FROM THE 03 UTC SREF ACROSS PART
OF SOUTH CENTRAL MT...WE ALSO MENTIONED ISOLATED STORMS FROM 18 TO
03 UTC. ONE OTHER ITEM OF NOTE TODAY WILL BE STRONG WINDS IN PARTS
OF THE AREA...ESPECIALLY AROUND SHERIDAN...WHERE WE COULD BE RIGHT
AT THE CUSP OF HIGH WIND WARNING CRITERIA WITH REGARD TO SUSTAINED
SPEEDS AT TIMES. MOS GUIDANCE SUGGESTS WINDS JUST UNDER THE 40 MPH
HEADLINE CRITERIA...SO WE HELD OFF ON A WARNING FOR NOW.
WHERE HYDROLOGY ISSUES ARE CONCERNED...MUSSELSHELL COUNTY HAS BEEN
DROPPED FROM THE FLASH FLOOD WATCH FOR BURN SCAR AREAS SINCE WE DO
NOT EXPECT MUCH MORE RAIN THERE. WE LEFT THE REST OF THE WATCH FOR
NOW...BUT IT MAY BE CANCELLED LATER TODAY OR THIS EVENING.
TONIGHT...A DRYING TREND WILL CONTINUE...AND IN FACT MOST OF SOUTH
CENTRAL MT WILL BE PRECIPITATION-FREE BY 06 UTC AS CONVECTION DIES
OUT. PRECIPITATION IN SOUTHEASTERN MT WILL ALSO SLOWLY PULL OUT AS
FORCING WEAKENS AND HEADS EAST...BUT THE 00 UTC GUIDANCE SUPPORTED
A CONTINUATION OF CATEGORICAL POPS IN EXTREME SOUTHEASTERN MT NEAR
BAKER AND EKALAKA THROUGH THE NIGHT. ADMITTEDLY...THOSE POPS COULD
BE A BIT HIGH...ESPECIALLY SINCE THERE IS A SUBTLE TREND IN THE 00
UTC MODELS TO PULL THE 700- AND 500-HPA LOWS EAST SLIGHTLY FASTER.
TUE...WE LEFT SOME CHANCE POPS IN PLACE OVER SOUTHEASTERN MT...BUT
IF THE NEXT MODEL CYCLE OR TWO CONTINUES ON A SLIGHTLY FASTER EXIT
OF THE PRECIPITATION...THOSE POPS MAY BE REDUCED FURTHER. SOME SUN
WILL LEAD TO A WARMER DAY...ESPECIALLY IN SOUTH CENTRAL MT. WE MAY
HAVE SOME AFTERNOON CUMULUS BUILDUPS THOUGH WITH RESIDUAL MOISTURE
IN THE BOUNDARY LAYER FROM THE RECENT RAIN. WE COULD ALSO HAVE FOG
ISSUES AT SOME POINT IN THE NEXT FEW DAYS THANKS TO THAT ENHANCED
MOISTURE. SCHULTZ
.LONG TERM...VALID FOR WED...THU...FRI...SAT...SUN...
FOCUS OF ATTENTION ON THE EXTENDED PACKAGE WILL TURN TO A DEEP
WESTERN TROUGH PROGGED TO MOVE INLAND ON TUESDAY. INCREASING
SOUTHWEST FLOW ALOFT WILL MOVE INTO WESTERN SECTIONS WEDNESDAY.
LINGERING EASTERLY FLOW AT THE LOW LEVELS AND SOME MID LEVEL
MOISTURE WILL PRODUCE WEAK CAPE AND SHEAR. INCREASING DIFFLUENT
FLOW SHOULD TRIGGER SCATTERED SHOWERS AND THUNDERSTORMS OVER THE
WEST...SO MAINTAINED SCATTERED POPS FROM BILLINGS WESTWARD.
HEIGHTS LOWER THURSDAY AS THE TROUGH MOVES SLOWLY EASTWARD.
DIFFLUENT FLOW INCREASES WITH INCREASING SHEAR. LOW LEVEL EASTERLY
WINDS WILL KEEP DEWPOINTS IN THE UPPER 40S TO AROUND 50. LOOKS
LIKE A BETTER CHANCE OF CONVECTION FOR THE WESTERN HALF OF THE
AREA. CAPE WAS NOT TREMENDOUS...BUT WITH INCREASING SHEAR...COULD
HAVE SOME STRONG STORMS. WILL HAVE TO MONITOR THIS AS THE DAY
APPROACHES.
MODELS DIFFER A BIT ON HOW FRIDAY PANS OUT. THE ECMWF WANTS TO
KICK A STRONG SHORTWAVE ACROSS THE AREA. THE GFS WAS FASTER WITH
IT AND SENDS IT THROUGH THURSDAY NIGHT AND FRIDAY MORNING. THE
ECMWF WOULD PRODUCE STRONGER LIFT AND PROVIDE A MUCH BETTER CHANCE
FOR SHOWERS AND THUNDERSTORMS. WILL KEEP SCATTERED POPS FOR THE
WESTERN HALF OF THE AREA. IF THE GFS PANS OUT...FRIDAY WOULD BE
MAINLY DRY AS MUCH DRIER MID LEVEL AIR PULLS ACROSS THE AREA
BEHIND THE SHORTWAVE. ONCE THE SHORTWAVE MOVES ACROSS...DRIER MID
LEVEL AIR WILL SWEEP THROUGH AND LIMIT THE CHANCE OF CONVECTION AS
ENERGY STAYS NORTH. THIS DRIER AIR SHOULD ALLOW FOR WARMER
TEMPERATURES FOR THE END OF THE WEEK INTO THE WEEKEND BUT NOTHING
TREMENDOUSLY WARM WITH SEASONAL HEIGHTS. TWH
&&
.AVIATION...
RAIN CAN BE EXPECTED TO CONTINUE EAST OF BILLINGS TODAY WITH
CONDITIONS OCCASIONALLY LOWERING TO MVFR. AREAS ALONG THE EAST
SLOPES FROM NYE TO RED LODGE CAN ALSO EXPECT PERSISTENT SHOWERS
TODAY. THIS WILL CAUSE MOUNTAIN OBSCURATIONS. THE REST OF THE AREA
WILL RECEIVE SCATTERED SHOWERS WITH A DECREASING TREND IN COVERAGE
THIS AFTERNOON.
NORTH TO NORTHWEST WINDS WILL BE STRONG TODAY FROM BILLINGS AND
SHERIDAN EASTWARD. GUSTS OF 45 TO 50 MPH CAN BE EXPECTED AT
SHERIDAN...MILES CITY AND BAKER. BILLINGS WILL GET GUSTS OF 35 TO
40 MPH. THE WINDS AND SHOWERS WILL DECREASE THIS EVENING. TWH
&&
.PRELIMINARY POINT TEMP/POPS...
TDY TUE WED THU FRI SAT SUN
-------------------------------------------------------
BIL 061 044/068 043/068 049/071 049/075 050/075 050/074
4/W 31/B 02/T 42/T 42/T 22/T 22/T
LVM 060 038/069 040/066 040/065 041/068 042/069 041/068
7/W 41/B 14/T 44/T 43/T 32/T 22/T
HDN 059 045/069 044/070 049/073 048/078 050/077 050/076
6/W 41/B 02/T 32/T 32/T 22/T 22/T
MLS 056 046/063 044/066 050/070 050/075 052/076 053/076
+/R 73/W 12/T 22/T 22/T 22/T 22/T
4BQ 051 044/060 043/066 048/070 049/076 051/076 052/077
+/W 74/W 22/T 21/N 22/T 22/T 22/T
BHK 051 042/056 041/062 047/066 048/070 051/074 052/073
+/R +5/W 22/T 21/N 22/T 22/T 33/T
SHR 053 041/063 038/067 046/071 046/075 048/075 048/074
7/W 41/N 12/T 32/T 32/T 22/T 22/T
&&
.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...FLASH FLOOD WATCH IN EFFECT THROUGH LATE TONIGHT FOR ZONES
30-31-36>38-57-58.
WY...NONE.
&&
$$
WEATHER.GOV/BILLINGS
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