FXUS65 KBYZ 012230
AFDBYZ
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BILLINGS MT
330 PM MST TUE DEC 1 2009
.SHORT TERM...VALID FOR WED AND THU...
SNOW HAS FOR THE MOST PART SHIFTED SOUTH OF OUR AREA NOW...WITH
BAROCLINIC ZONE IN WYOMING. LIGHT NWLY UPSLOPE SNOW SHOWERS
LINGER...BUT ANY ADDITIONAL ACCUMULATION WILL BE VERY LIGHT...SO
HAVE CANCELLED THE REMAINING ADVISORIES.
WE WILL BE UNDER THE INFLUENCE OF COLDER NLY FLOW THE NEXT COUPLE
DAYS AS UPPER RIDGE REMAINS ANCHORED ALONG THE PACIFIC COAST. A
COUPLE SHORTWAVES EVIDENT ON WATER VAPOR IMAGERY WILL AFFECT OUR
AREA...THE FIRST PUSHING INTO NE MONTANA NOW AND THE OTHER IN
NORTHERN ALBERTA. WEAK QG FORCING EXISTS WITH EACH OF THESE WAVES
WITH A MODEST INCREASE IN MOISTURE FROM THE NORTH. LOW LEVEL
INSTABILITY THROUGH DENDRITIC LAYER...ALBEIT SHALLOW...SHOULD BE
ENOUGH TO PRODUCE SOME LIGHT SNOW SHOWERS. BEST CHANCE OF SNOW
SHOWERS WILL BE IN OUR EAST TONIGHT...THEN ACROSS OUR CENTRAL AND
EAST PARTS WED INTO WED NITE...PERHAPS LASTING INTO EARLY THU.
WINDS LOOK TO VEER ENOUGH TO BRING THE LIGHT PCPN THROUGH BILLINGS
AND TO OUR RED LODGE/BEARTOOTH FOOTHILLS BY WED AFTN.
CYCLONIC NORTH FLOW DOES FAVOR OUR BIG HORN MTNS AND HAVE RAISED
POPS THERE TO LIKELY TOMORROW AND WED NIGHT. HOWEVER WITH 700MB
TEMPS FALLING TO AROUND -20C THEY COULD LOSE MUCH OF THE DENDRITIC
LAYER SO WILL KEEP SNOW AMOUNTS LIGHT...AND AS ALREADY MENTIONED
INSTABILITY IS FAIRLY SHALLOW.
WINDS HAVE DECREASED SINCE EARLIER TODAY AND DO NOT SEE ANY WIND
ISSUES THE NEXT TWO DAYS...THOUGH NW WINDS WILL BE A BIT GUSTY
AGAIN TOMORROW AFTN IN OUR EAST.
TEMPS WILL REMAIN BELOW NORMAL WITH HIGHS IN THE UPPER TEENS TO
MID 20S BOTH WED AND THU...WITH ENERGY FROM THE NORTH PROVIDING
REINFORCING SHOTS OF COLDER AIR. LOW TEMPS A BIT TRICKY
CONSIDERING POTENTIAL FOR WIND AND PCPN. AIRMASS IS PLENTY COLD
ENOUGH FOR SOME VERY CHILLY NIGHTS BUT THINK DOWNSLOPE GRADIENTS
WILL KEEP TEMPS FROM FALLING TO FAR TONIGHT EXCEPT IN OUR FAR WEST
CLOSER TO SFC HIGH CENTER. HAVE LOWERED TEMPS TONIGHT A FEW
DEGREES. LEE SIDE TROFFING SHOULD COMMENCE LATE THU NITE...A BIT
LATER THAN PREVIOUSLY THOUGHT...SO HAVE DROPPED TEMPS THIS PERIOD
ESPECIALLY IN OUR EAST.
JKL
.LONG TERM...VALID FOR FRI...SAT...SUN...MON...TUE...
THE EXTENDED PERIOD BEGINS FRIDAY MORNING WITH GENERALLY FAIR
AGREEMENT AMONG OPERATIONAL MODELS. THE REMNANTS OF AN UPPER-
LEVEL RIDGE SHOULD CONTINUE TO INFLUENCE THE CWA ON FRIDAY. A
DOWNSLOPE PRESSURE GRADIENT WILL BE IN PLACE AND THEREFORE WARMER
AND DRY CONDITIONS ARE EXPECTED. BOTH MODELS DEVELOP AN UPPER-
LEVEL LOW OVER THE PACIFIC NORTHWEST FOR SATURDAY AND BEYOND.
TRENDED FORECASTS TOWARD THE ECMWF WHICH APPEARS TO BE A BIT
FASTER THAN THE GFS. THE EVOLUTION OF THIS FEATURE BECOMES
STAGNANT IN BOTH THE GFS AND ECMWF. THIS KEEPS AN AREA OF
DIFFLUENT FLOW AND Q-VECTOR CONVERGENCE OVER THE CWA FOR A NUMBER
OF DAYS. KEPT POPS MAINLY OVER WESTERN ZONES FOR EARLY SATURDAY
BEFORE SPREADING EASTWARD SATURDAY THROUGH LATE MONDAY. THE
UPPER-LOW OPENS INTO A WAVE AND EXITS THE REGION LATE TUESDAY.
TEMPERATURES WILL BE COLD THROUGH MUCH OF THE EXTENDED PERIOD.
850-MB TEMPS FALL TO AROUND -10 DEG C FOR SATURDAY TO THE TEENS
BELOW 0 FOR SUNDAY. A SLIGHT WARMING TREND SETS UP FOR MONDAY AND
BEYOND. SCHUKNECHT
&&
.AVIATION...
SNOW HAS DIMINISHED ACROSS THE FORECAST AREA THIS AFTERNOON.
LINGERING CLOUDS OVER SOUTHERN AND EASTERN PORTIONS OF THE CWA
MAY PRODUCE BRIEF PERIODS OF MVFR CONDITIONS INTO THIS EVENING.
GUSTY NWLY WINDS OVER MAINLY EASTERN ZONES WILL WEAKEN THIS
EVENING. SCATTERED SHOWERS WILL BE POSSIBLE WEDNESDAY MORNING
ACROSS CENTRAL AND EASTERN ZONES. EXPECT PERIODS OF MVFR
CONDITIONS WITH LOCALIZED IFR CONDITIONS WITHIN AREAS OF
PRECIPITATION DURING THIS TIME. SCHUKNECHT
&&
.PRELIMINARY POINT TEMP/POPS...
WED THU FRI SAT SUN MON TUE
-----------------------------------------------------------
BIL 013/024 009/024 012/035 020/029 012/020 006/016 006/023
12/J 22/J 11/B 12/J 33/J 21/B 21/B
LVM 003/022 002/024 010/032 016/028 004/017 005/016 006/022
01/B 11/U 01/B 22/J 33/J 22/J 21/B
HDN 011/026 009/025 010/036 017/028 012/022 002/020 002/026
23/J 32/J 11/B 12/J 22/J 21/B 21/B
MLS 014/024 008/022 009/034 013/026 011/021 004/018 004/021
23/J 31/B 11/B 11/B 12/J 21/B 21/B
4BQ 015/024 009/020 006/034 012/028 010/020 004/020 009/023
23/J 32/J 11/B 11/B 12/J 21/B 22/J
BHK 014/022 006/018 003/029 007/026 008/021 002/019 005/020
23/J 32/J 11/B 11/B 12/J 21/B 22/J
SHR 011/023 007/022 005/037 016/032 010/020 004/019 003/021
23/J 32/J 11/B 12/J 23/J 32/J 22/J
&&
.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...NONE.
WY...NONE.
&&
$$
WEATHER.GOV/BILLINGS
