Area Forecast Discussion
Issued by NWS Billings, MT

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FXUS65 KBYZ 202120
AFDBYZ

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BILLINGS MT
320 PM MDT SUN APR 20 2014

.SHORT TERM...VALID FOR MON AND TUE...

MADE SEVERAL RELATIVELY MINOR CHANGES TO THE SHORT TERM FORECAST
TODAY...ALTHOUGH THE OVERALL FORECAST REMAINS THE SAME. CHANGES
WERE CONFINED MAINLY TO TUESDAY AND THE NEXT ROUND OF PRECIP.

BREEZY CONDITIONS TODAY WILL TAPER OFF THIS EVENING AND
OVERNIGHT. WARM AND DRY CONDITIONS TODAY WILL CONTINUE THROUGH
MONDAY AND INTO TUESDAY. WITH LOW 70S MONDAY...AND POTENTIAL FOR
MID 70S TUESDAY. DID RAISE TEMPS FOR TUESDAY...AS GUIDANCE SEEMS
TO BE PUSHING 80S. WARM TUESDAY WOULD NOT SURPRISE ME MUCH DO TO
WARM START TO THE DAY...AND LATE TIMING OF FRONT INTO THE REGION
TO ADD COMPRESSIONAL HEATING TO THE MIX. ALTHOUGH CLOUD COVER MAY
HAMPER WARM UP SOME...INITIALLY DRY SURFACE CONDITIONS SHOULD
SUPPORT QUICKER WARMUP.

SHOWERS WILL MAINLY STAY ON THE HIGH TERRAIN THROUGH TUESDAY
MORNING...SPREADING SLOWLY EASTWARD THROUGH THE DAY...WITH
GREATEST IMPACTS LATE AFTERNOON THROUGH THE OVERNIGHT HOURS.
CANNOT RULE OUT THUNDER POTENTIAL AS THIS SYSTEM MOVES ACROSS THE
REGION...AS APPEARS TO BE FAIRLY CONVECTIVE. DID KEEP MENTION OF
ISOLATED THUNDER IN THE FORECAST THROUGHOUT TUESDAY NIGHT. BIGGEST
QUESTION MARK WITH THIS SYSTEM REALLY HINGES ON DRY AIR
INTRUSION...WHICH IS WHY KEPT MAINLY CHANCE POPS OR LOWER IN PLACE
OUTSIDE OF AREA MOUNTAINS. AAG

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

WE EXPECT COOL...WINDY AND POSSIBLY SHOWERY CONDITIONS WED AND THU
UNDER THE INFLUENCE OF A LARGE UPPER-LEVEL TROUGH. WE DON/T EXPECT
A SIGNIFICANT PRECIPITATION EVENT WITH THIS SYSTEM BECAUSE THE GFS
AND ECMWF RUNS FROM 12 UTC CONTINUE SHOWING THE CLOSED 500-HPA LOW
WHICH FORMS BY WED REMAINING OVER NORTHERN MT AND SOUTHERN CANADA.
THAT WILL ENABLE LOW-LEVEL WESTERLY/DOWNSLOPE WINDS IN SOUTHERN MT
AND NORTH CENTRAL WY...WHICH COULD GREATLY HINDER SHOWER COVERAGE.
WE ACTUALLY REDUCED POPS ACROSS THE PLAINS WED THROUGH THU IN MANY
LOCATIONS SO THAT THEY ARE ONLY IN THE 20 TO 40 PERCENT RANGE. THE
GREATEST PRECIPITATION CHANCES COULD COME ON THU OVER SOUTHEASTERN
MT IF WRAP-AROUND/STRATIFORM PRECIPITATION ON THE WEST SIDE OF THE
500-HPA LOW ENDS UP THAT FAR SOUTH /WHICH IS FAR FROM CERTAIN/.

BY FRI...SHORTWAVE RIDGING COULD CROSS THE REGION AHEAD OF ANOTHER
AMPLIFYING UPPER-LEVEL TROUGH WHICH THE 12 UTC MODEL SUITE EXPECTS
TO AFFECT THE ROCKIES SOMETIME NEXT WEEKEND. OUR CONFIDENCE IN THE
TIMING AND EVOLUTION OF THAT TROUGH IS BELOW NORMAL BECAUSE LITTLE
CONSENSUS EXISTS AMONG GUIDANCE WITH THOSE ITEMS...BUT IN ANY CASE
PRECIPITATION CHANCES WILL INCREASE AGAIN BY SAT AND SUN. SCHULTZ

&&

.AVIATION...

VFR CONDITIONS WILL CONTINUE TONIGHT AND MONDAY. THE GUSTY WEST TO
NORTHWEST WINDS WHICH ARE OCCURRING THIS AFTERNOON ARE EXPECTED TO
DIMINISH BY ABOUT 02 UTC AS MIXING DIMINISHES NEAR SUNSET. SCHULTZ

&&

.PRELIMINARY POINT TEMP/POPS...

    MON     TUE     WED     THU     FRI     SAT     SUN
-----------------------------------------------------------
BIL 039/071 046/077 046/057 037/057 035/059 039/062 041/054
    00/U    12/T    44/W    33/W    22/W    23/W    33/W
LVM 037/071 045/072 039/053 033/059 034/061 037/061 036/055
    00/U    26/T    75/W    33/W    22/W    24/W    33/W
HDN 035/072 039/079 041/058 034/055 032/061 035/063 038/055
    00/U    12/T    34/T    24/W    22/W    23/W    33/W
MLS 035/069 042/076 045/061 037/053 031/055 034/060 039/052
    00/U    01/B    33/T    24/W    31/B    22/W    33/W
4BQ 035/070 041/079 045/062 034/054 031/056 033/062 038/054
    00/U    02/T    23/T    23/W    21/B    23/W    33/W
BHK 033/066 037/074 046/063 036/050 028/050 030/055 035/047
    00/U    00/N    32/T    23/W    31/E    23/W    34/W
SHR 036/070 041/079 043/058 037/054 032/061 036/065 038/058
    00/U    02/T    23/T    23/W    22/W    23/W    33/W

&&

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

&&

$$
WEATHER.GOV/BILLINGS



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