Area Forecast Discussion
Issued by NWS Billings, MT

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FXUS65 KBYZ 282145
AFDBYZ

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BILLINGS MT
245 PM MST WED JAN 28 2015

.SHORT TERM...VALID FOR THU AND FRI...

SHORT WAVE THAT BROUGHT SOME SNOW TO THE HIGH COUNTRY LAST NIGHT
HAS EXCITED THE REGION...BUT COLD AIR IS BEING PULLED DOWN FROM
THE NORTH BEHIND IT. ASSOCIATED STRATUS ON VISIBLE SATELLITE
IMAGERY WAS MOVING INTO OUR NORTHERN ZONES AT MIDDAY AND IS
EXPECTED TO SPREAD ACROSS MUCH OF OUR CENTRAL/EASTERN ZONES BY
EVENING. CROSS SECTIONS INDICATE THE STRATUS WILL LINGER THROUGH
THE NIGHT BEFORE GRADUALLY DISSIPATING EARLY THURSDAY FROM WEST TO
EAST. THERE WILL BE A TYPICAL TRADE-OFF BETWEEN CAA AND LINGERING
STRATUS TONIGHT TO MAKE OVERNIGHT LOWS TRICKY IN OUR EAST...BUT
FEEL CAA WILL GENERALLY WIN OUT AND HAVE STUCK CLOSE TO INHERITED
FORECASTS/GUIDANCE. THERE WILL CERTAINLY BE A COOLER AIR MASS IN
PLACE OVER US TOMORROW...BUT NOTHING DRASTIC AND WE SHOULD BRIEFLY
SEE SOME SUNSHINE AROUND MIDDAY KEEPING US ON THE MILD SIDE
COMPARED TO SEASONAL AVERAGES.

THE OVERALL FLOW PATTERN IS STILL ANTICYCLONIC THURSDAY WITH SOME
WEAK QUASI LOW PRESSURE LINGERING OVER THE GREAT BASIN.
HOWEVER...WE BEGIN TO TRANSITION TO A BRISK NW FLOW ALOFT WITH
SHORT WAVE ENERGY OUT OF CANADA TRACKING THROUGH NE MONTANA BY
LATE FRIDAY NIGHT. THIS MAY OPEN THE DOOR TO UNSETTLED AND MUCH
COOLER WEATHER FOR THE WEEKEND. PLEASE SEE THE LONG TERM
DISCUSSION BELOW FOR MORE DETAILS. BT


.LONG TERM...VALID FOR SAT...SUN...MON...TUE...WED...

A CHANGE IN THE PATTERN TO COLDER WEATHER WITH PERIODS OF SNOW
APPEARS LIKELY FOR THE EXTENDED PERIOD BEGINNING ON SAT. WHILE
MODELS AGREED WITH THIS OVERALL SCENARIO...THE PATTERN DETAILS
DIFFERED BETWEEN THEM.

JET ENERGY WILL DIVE SE INTO THE AREA ON SAT ACCOMPANIED BY A
SHORTWAVE AND BACKDOOR COLD FRONT. GFS WAS THE MOST AGGRESSIVE
MODEL IN BRINGING QPF SW INTO THE AREA COMPARED TO THE OTHER
MODELS. THE CANADIAN AND ECMWF BRING THE QPF IN ON SAT NIGHT.
BASED ON THE TIMING UNCERTAINTY...SLOWED DOWN ARRIVAL OF HIGHER
POPS IN THE SW PART OF THE AREA ON SAT...AND WENT WITH MAINLY
CHANCE POPS SAT NIGHT.

FLOW THEN TRANSITIONS INTO A FLAT NW FLOW ON THE MODELS FOR SUN
INTO TUE. MODELS HAD PACIFIC MOISTURE OVERRUNNING THE SURFACE
BOUNDARY ON SUN BUT DIFFERED IN THEIR QPF DEPICTIONS. WEAK
SHORTWAVE ENERGY REINFORCES THE COLD AIR OVER THE REGION ON MON
AND TUE WHILE PACIFIC MOISTURE CONTINUES TO OVERRUN THE BOUNDARY.
BLENDED POPS FOR THIS TIME FRAME WITH THE SUPERBLEND GUIDANCE AS
THE MODELS DIFFERED IN PRECIPITATION DETAILS. INHERITED TUE POPS
LOOKED REASONABLE.

ENERGY THEN WRAPS AROUND THE HUDSON BAY LOW FOR THE END
OF THE PERIOD. THIS ENERGY WILL REINFORCE THE COLD AIRMASS OVER
THE AREA. WILL CONTINUE TO USE A MODEL BLEND FOR POPS.

TEMPERATURE PROFILES ALSO DIFFERED BETWEEN THE MODELS FOR MUCH OF
THE PERIOD SO WENT WITH SUPERBLEND. RESULT WAS PERIODS OF
SEASONAL AND BELOW NORMAL TEMPERATURES. ARTHUR
&&

.AVIATION...

MVFR/IFR CONDITIONS WILL AFFECT AREAS E OF KBIL THROUGH EARLY THU
MORNING DUE TO CLOUDS AND AREAS OF FOG. SOME FREEZING DRIZZLE IS
ALSO POSSIBLE AROUND KBHK. THERE WILL BE LOCAL OBSCURATIONS OVER
THE NE BIG HORNS THIS EVENING. OTHERWISE...VFR WILL PREVAIL OVER
THE AREA THROUGH THU. GUSTY N TO NW SURFACE WINDS FROM KBIL TO
KSHR E WILL DIMINISH EARLY THIS EVENING. ARTHUR
&&

.PRELIMINARY POINT TEMP/POPS...

    THU     FRI     SAT     SUN     MON     TUE     WED
-----------------------------------------------------------
BIL 029/048 030/050 028/038 019/030 022/041 027/039 019/032
    00/U    00/U    03/W    33/J    33/W    32/W    23/J
LVM 028/048 027/048 024/040 020/036 025/045 029/043 024/038
    00/U    00/U    03/W    23/J    43/W    32/W    23/W
HDN 025/046 025/048 023/035 015/029 017/038 021/035 015/030
    00/U    00/U    03/W    32/J    33/J    33/J    23/J
MLS 026/044 027/044 024/032 011/023 014/032 017/028 011/025
    00/B    00/U    04/J    22/J    22/J    23/J    22/J
4BQ 026/048 027/049 025/037 015/029 018/039 021/035 016/030
    00/B    00/U    03/W    32/J    22/W    23/J    22/J
BHK 025/040 024/043 021/028 007/020 009/029 015/027 009/023
    20/B    00/U    04/J    32/J    22/J    23/J    22/J
SHR 022/044 020/045 020/037 015/029 016/040 020/038 017/032
    00/U    00/U    03/W    32/J    22/W    32/J    23/J

&&

.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...NONE.
WY...NONE.

&&

$$
WEATHER.GOV/BILLINGS


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