Area Forecast Discussion
Issued by NWS Billings, MT

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000
FXUS65 KBYZ 012040
AFDBYZ

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BILLINGS MT
240 PM MDT WED OCT 1 2014

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

COLD POOL ALOFT HAS YIELDED SOME MOSTLY LIGHT INSTABILITY DRIVEN
SHOWERS IN NW FLOW ALOFT THIS AFTERNOON. THIS ACTIVITY WILL
DIMINISH QUICKLY AROUND SUNSET AS WE LOSE DAYTIME HEATING AND AS
WEAK RIDGING SPREADS IN FROM THE WEST. DOWNSLOPE GRADIENTS WILL
TIGHTEN SOMEWHAT TONIGHT IN RESPONSE TO APPROACHING CLIPPER. THUS
EXPECT SOME SW WIND ALONG THE FOOTHILLS AND TEMPS NOT AS COOL AS
THEY WOULD BE OTHERWISE.

MAIN FORECAST ISSUES IN THE SHORT TERM INVOLVE THE SHORTWAVE AND
COLD FRONT EMERGING FROM NW CANADA. MAX TEMPS WILL BE ACHIEVED
EARLY TOMORROW AS COLD ADVECTION COMMENCES IN THE MORNING...WITH A
FRONT EXPECTED TO REACH SHERIDAN BY AROUND 18Z. HAVE SIDED WITH
THE GFS/ECMWF REGARDING FRONTAL TIMING. STRONG COLD ADVECTION/
PRESSURE RISES WILL RESULT IN A FEW HOURS OF GUSTY N-NW WINDS
TOMORROW...WITH SFC TEMPS IN THE UPPER 30S AND 40S IN THE POST
FRONTAL REGIME AS 850MB TEMPS FALL TO THE LOWER SINGLE DIGITS. WE
SHOULD SEE A BRIEF PERIOD OF SHOWER ACTIVITY PER THE QG FORCING
AND MID LEVEL FRONTOGENESIS...ALONG WITH THE DEVELOPMENT OF LOW
LEVEL UPSLOPE FLOW FOR OUR SOUTH. TEMPS SHOULD TURN COLD ENOUGH TO
MIX WITH WET SNOW ALONG OUR FOOTHILLS AND UP AT JUDITH GAP. WET
BULB ZERO HEIGHTS WILL BE QUITE LOW SO WOULD ANTICIPATE A MIX WITH
SNOW OR SNOW PELLETS WITHIN ANY HEAVIER SHOWERS ACROSS THE LOWER
ELEVATIONS...AND THERE IS A LITTLE POTENTIAL HERE AS MODELS HAVE
BEEN CONSISTENTLY SHOWING SOME MID LEVEL CAPE INTERSECTING THE
DENDRITIC LAYER. ALSO COULD SEE SOME NW FLOW BANDING EAST OF THE
SNOWY MOUNTAINS. ALTHOUGH IT WILL BE SHORT-LIVED...TOMORROW
SHOULD SEE SOME INTERESTING FALL-LIKE WEATHER WITH THIS CLIPPER.

SUBSIDENCE/DRYING WILL END ANY PCPN QUICKLY EARLY TOMORROW
EVENING. LOOKS LIKE ANOTHER FREEZE FOR MUCH OF THE AREA THURSDAY
NIGHT AS SFC RIDGE BUILDS IN...WITH CORE OF SFC RIDGE IN OUR WEST
AND CENTRAL PARTS...SUGGESTING THE BEST POTENTIAL FOR RADIATIONAL
COOLING IN THIS AREA AND PERSISTENT NW WINDS IN OUR EAST. HAVE
DROPPED EXPECTED LOWS A BIT MORE...CONSISTENT WITH GUIDANCE
TRENDS. RECORD LOW OF 23 DEGREES AT LIVINGSTON WILL BE CHALLENGED.

WARMER TEMPS COMING FRIDAY AS RIDGE BEGINS TO BUILD BACK IN FROM
THE WEST...BUT THE ONSET OF DOWNSLOPE FLOW HAS TRENDED A BIT
SLOWER. SHOULD SEE HIGHS NEAR 50F NEAR THE DAKOTAS BORDER AND THE
LOW TO MID 60S ALONG OUR WESTERN FOOTHILLS. LEE SIDE TROF FRIDAY
NIGHT WILL RESULT IN A WARMER AND BREEZY NIGHT ESPECIALLY ALONG
OUR FOOTHILLS. NO CHANCE OF PCPN FROM LATE THURSDAY NIGHT THROUGH
FRIDAY NIGHT.

JKL

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

VERY LITTLE IN THE WAY OF CHANGES FOR THE EXTENDED FORECAST
PERIOD THIS AFTERNOON...AS MODELS ALL REMAIN IN GOOD AGREEMENT
THROUGH PERIOD. UPPER LEVEL RIDGING CENTERED OVER THE PACIFIC
NORTHWEST WILL KEEP PERSISTENT DRY NORTHWEST FLOW ACROSS THE
REGION THROUGH THE BULK OF THE PERIOD. MODELS ARE NOT SHOWING
ANYTHING IN THE WAY OF QPF AT THIS TIME..BUT FLOW WOULD ALLOW FOR
POTENTIAL OF BACKDOOR ENERGY INTO EASTERN MOST ZONES AT LEAST...SO
WILL NEED TO WATCH THOSE AREAS CLOSELY IN COMING SHIFTS. HAVE
CONTINUED WITH DRY FORECAST. THERE ARE SOME INDICATION OF SLIGHT
STRONGER WAVES FLATTENING THE FLOW BEGINNING TUESDAY...BUT
CURRENTLY BEST ENERGY STAYS NORTH...AND CONDITIONS APPEAR TO
REMAIN DRY.

AS FOR TEMPERATURES...EXPECT TO SEE ABOVE AVERAGE READING THROUGHOUT
THE PERIOD. RIDGING AND DOWNSLOPE FLOW WILL RESULT IN TEMPS IN THE UPPER
60S TO MID 70S THROUGHOUT THE EXTENDED PERIOD. AAG

&&

.AVIATION...

ISOLATED TO SCATTERED SHOWERS ARE SPREADING ACROSS MUCH OF THE
REGION...RESULTING IN LOCALIZED MVFR TO IFR CONDITIONS. PERIODIC MOUNTAIN
OBSCURATIONS CAN ALSO BE ANTICIPATED IN ANY SHOWER ACTIVITY. OTHERWISE...VFR
CONDITIONS WILL PREVAIL. GUSTY NORTHWEST WINDS CONTINUE IN MOST
AREAS THIS AFTERNOON...WITH GUSTS AS HIGH AS 25 KNOTS IN SOME
LOCATIONS. WINDS WILL TAPER OFF LATE THIS EVENING. AAG

&&

.PRELIMINARY POINT TEMP/POPS...

    THU     FRI     SAT     SUN     MON     TUE     WED
-----------------------------------------------------------
BIL 044/052 030/060 047/073 047/069 048/071 049/070 047/066
    13/W    10/U    00/U    11/U    10/U    11/B    11/B
LVM 036/054 025/064 041/070 040/067 042/070 043/070 041/067
    12/W    10/B    00/U    11/U    11/U    11/U    11/B
HDN 039/055 027/060 041/074 045/069 046/071 047/071 044/069
    14/W    10/U    00/U    11/U    11/U    11/B    11/B
MLS 040/052 028/057 038/071 045/067 046/068 045/067 044/066
    13/W    00/U    00/U    11/U    11/B    11/B    11/B
4BQ 039/056 029/056 038/071 046/066 045/068 045/067 044/067
    14/W    20/U    00/U    11/U    11/U    11/B    11/B
BHK 038/052 028/050 032/066 042/062 043/063 041/062 040/062
    13/W    00/N    00/B    11/N    11/B    11/B    11/B
SHR 036/057 026/057 037/071 043/067 042/070 043/069 042/068
    15/W    20/U    00/U    11/U    10/U    11/U    11/B

&&

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

&&

$$
WEATHER.GOV/BILLINGS



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