Area Forecast Discussion
Issued by NWS Billings, MT

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FXUS65 KBYZ 200959
AFDBYZ

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BILLINGS MT
359 AM MDT SUN APR 20 2014

.SHORT TERM...VALID FOR TDY AND MON...

UPPER LEVEL DISTURBANCE WILL CROSS THE NORTHERN PORTION FROM WEST
TO EAST TODAY. THIS LEAVES SOUTHERN MONTANA/NORTHERN WYOMING ON
THE WINDY AND DRY SIDE OF THIS SYSTEM WITH A WEAK COLD FRONT
TRAILING THROUGH THE AREA. COULD SEE A FEW LIGHT SHOWERS THIS
MORNING OVER WESTERN AREAS WITH THE FRONT...MAINLY IN THE
MOUNTAINS. BY MID DAY WINDS WILL PICK UP WITH GUSTS OF 30 TO 40
MPH THROUGH THIS AFTERNOON OUT OF THE WEST. TEMPERATURES WILL ONCE
AGAIN PUSH INTO THE MID 60S TO AROUND 70 DEGREES THIS AFTERNOON
THANKS TO THE STRONG DOWNSLOPE FLOW. WINDS WILL DIMINISH TONIGHT
FOR A MOSTLY CLEAR AND COOL NIGHT. MONDAY WILL SEE WINDS TURN
AROUND TO THE SOUTH AND EAST DURING THE DAY WITH MOSTLY SUNNY
CONDITIONS ALLOWING TEMPERATURES INTO THE LOWER 70S. CLOUD COVER
WILL INCREASE OVER THE AREA MONDAY NIGHT AS DIFFLUENT FLOW AND
PACIFIC MOISTURE ALOFT SPREAD OVER THE AREA. CAN`T RULE OUT A FEW
SHOWERS OVER WESTERN MOUNTAINS/VALLEYS AFTER MIDNIGHT BUT BETTER
CHANCES FOR PRECIPITATION HOLD OFF UNTIL TUESDAY AFTERNOON.
CHAMBERS

.LONG TERM...VALID FOR TUE...WED...THU...FRI...SAT...

MODELS ARE IN BETTER AGREEMENT WITH MIDWEEK WEATHER SYSTEM THOUGH
EXACT TRACK STILL MAY VARY. HEIGHTS FALL ACROSS MONTANA AND
WYOMING ON TUESDAY IN ADVANCE OF A TROUGH MOVING THROUGH THE
PACIFIC NORTHWEST. A NEGATIVELY TILTED SHORTWAVE MOVES THROUGH
TUESDAY NIGHT INTO EARLY WEDNESDAY. THIS SHORTWAVE EVOLVES INTO A
CUT OFF UPPER LOW OVER NORTHERN MONTANA ON WEDNESDAY AND THIS WAVE
DRIFTS EASTWARD INTO EASTERN MONTANA AND THE DAKOTAS ON THURSDAY.
MODELS THEN SHOW A BREAK ON FRIDAY WITH ANOTHER SYSTEM APPROACHING
ON SATURDAY. AFTER SATURDAY CONFIDENCE IS LOW ON TRACK OF INCOMING
SYSTEM.

TUESDAY LOOKS WARM AS SURFACE MIXING INCREASES AS A DEEP SURFACE
LOW DEVELOPS NORTHWEST OF BILLINGS CLOSER TO HARLOWTON/HELENA
AREAS. SOUTHWEST FLOW ALOFT BRINGS MOISTURE AND SHOWER THREAT TO
THE WESTERN ZONES AND STRONG SOUTHEASTERLY SURFACE FLOW DEVELOPS
OVER EASTERN MONTANA. MODELS SHOWING SOME ADVECTION OF HIGHER
DEWPOINTS IN THE SOUTHEASTERLY FLOW BUT AT THIS POINT ITS INTO
NORTHEAST MONTANA AND NOT AS MUCH SUPPORT FOR SHOWERS OR
THUNDERSTORMS OVER THE EASTERN AND CENTRAL ZONES DESPITE
TEMPERATURES IN THE 70S. ELEVATED SHOWERS AND THUNDERSTORMS
POSSIBLE TUESDAY NIGHT AS THE NEGATIVELY TILTED WAVE ROTATES
THROUGH THE AREA.

MODELS AGREE AIRMASS DRIES OUT A BIT ON WEDNESDAY AS THE WAVE
DEVELOPS OVER NORTHERN MONTANA. TRENDED POPS LOWER POPS OVER
SOUTHEAST MONTANA TO REFLECT THIS PROCESS BUT ATMOSPHERE WILL
STILL BE UNSTABLE SO IT WILL NOT BE COMPLETELY DRY...JUST MAY NOT
SEE VERY WET STORMS. SHOULD SEE 10-15 DEGREES COOLING ON WEDNESDAY
AND MAY BE EVEN COOLER IF CLOUD COVER IS GREATER THAN EXPECTED.

BIGGEST QUESTION OF FORECAST IS ON THURSDAY AS THE SYSTEM BEGINS
TO TRACK EASTWARD AND HOW MUCH WRAP AROUND MOISTURE WORKS INTO
SOUTHERN MONTANA. SYSTEM IS TRENDING NORTHWARD SO WIDESPREAD
ORGANIZED PRECIPITATION IN SOUTHERN MONTANA AIDED BY UPSLOPE
CONTINUES TO BE LESS LIKELY SO HAVE MINIMAL CONCERNS ABOUT THE
RAINFALL AMOUNTS CAUSING HYDROLOGIC PROBLEMS. THURSDAY WILL BE
EVEN COOLER AND COULD BE FAIRLY BREEZY AS STRONG MIDLEVEL
NORTHWEST WINDS CROSS THE AREA BEHIND THE LOW.

EXPECT REBOUNDING TEMPERATURES ON FRIDAY AND DECREASED CHANCE OF
ANY SHOWER ACTIVITY. MODELS DISAGREE ON WHETHER SATURDAY WILL
HAVE A PERIOD OF SOUTHWEST FLOW AHEAD OF THE NEXT SYSTEM OR
WEATHER HEIGHT FALLS WILL ALREADY BE MOVING INTO THE AREA. BORSUM

&&

.AVIATION...

COLD FRONT WILL MOVE ACROSS THE AREA PRODUCING SOME CLOUD COVER
BUT VERY LITTLE SHOWER ACTIVITY. EXPECT WESTERLY WIND GUSTS OF 30 KT
DURING THE AFTERNOON HOURS. WINDS WILL DECREASE THIS EVENING.
BORSUM
&&

.PRELIMINARY POINT TEMP/POPS...

    TDY MON     TUE     WED     THU     FRI     SAT
-------------------------------------------------------
BIL 068 039/071 046/075 046/057 037/057 035/061 039/062
    1/N 00/U    12/T    45/W    33/W    22/W    22/W
LVM 065 037/071 045/072 039/053 033/059 034/064 037/062
    1/N 00/U    26/T    76/W    33/W    22/W    22/W
HDN 070 035/072 039/078 041/058 034/055 032/061 035/063
    1/N 00/U    12/T    35/T    44/W    22/W    22/W
MLS 069 035/069 042/074 045/061 037/053 031/055 034/061
    1/N 00/U    01/B    35/T    34/W    31/B    22/W
4BQ 070 035/070 041/078 045/062 034/054 031/057 033/063
    1/N 00/U    02/T    25/T    33/W    21/B    22/W
BHK 067 033/066 037/070 046/063 036/050 028/052 030/057
    1/N 00/U    00/N    35/T    34/W    31/E    22/W
SHR 068 036/070 041/078 043/058 037/054 032/061 036/066
    1/N 00/U    02/T    25/T    43/W    22/W    22/W

&&

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

&&

$$
WEATHER.GOV/BILLINGS



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