Area Forecast Discussion
Issued by NWS Billings, MT

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FXUS65 KBYZ 160306
AFDBYZ

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE BILLINGS MT
906 PM MDT TUE APR 15 2014

.UPDATE...

UPDATED FORECAST POPS/TEMPERATURES/PRECIPITATION AND SNOW
ACCUMULATIONS TONIGHT INTO TOMORROW. THE LATEST MODELS HAVE
ADJUSTED FRONTOGENESIS/ISENTROPIC LIFT A BIT FURTHER WEST WITH THE
LATEST RUNS...TOWARD THE EARLIER GFS SOLUTION. THIS PUTS THE BEST
LIFT OVERNIGHT TONIGHT THROUGH TOMORROW MORNING IN A BAND FROM
ROUNDUP TO NEAR BILLINGS TO NORTHEAST OF SHERIDAN WYOMING. THIS
SHIFT WESTWARD ALSO MEANS COLDER AIR WILL BE SHIFTING FURTHER
SOUTH AND WEST AS WELL. THIS LIFT WILL CONTINUE TO FIGHT DOWNSLOPE
NORTHWESTERLY WINDS THROUGH THE NIGHT SO HAVE KEPT POPS IN THE
LIKELY RANGE AS OPPOSED TO CATEGORICAL FOR NOW. ALSO...EVEN WITH
COOLER TEMPERATURES HAVE KEPT SNOW ACCUMULATIONS PRETTY LOW FOR
THE PLAINS AS LOW SHOULD BOTTOM OUT WITHIN A 3 DEGREES OF FREEZING
IN MOST LOCATIONS. CAN`T RULE OUT HIGHER HILLS/FOOTHILLS OF
CENTRAL ZONES SEEING A FEW INCHES OF ACCUMULATION ON GRASSY
SURFACES BUT OVERALL LESS THAN AN INCH SEEMS MOST LIKELY IN MOST
LOCATIONS. WINDS WILL WEAKEN SOMEWHAT OVERNIGHT AS STRONGER
SURFACE PRESSURE RISES PASS SOUTH OF THE AREA...BUT UNTIL THEN
WILL CONTINUE TO SEE OCCASIONAL GUSTS OVER 30 MPH. CHAMBERS

&&

.SHORT TERM...VALID FOR WED AND THU...

UPPER LEVEL DISTURBANCE AND STRONG JET MAX SUPPORTING A PACIFIC
COLD FRONT WILL CONTINUE TO MOVE ACROSS OUR AREA THIS EVENING INTO
TONIGHT...BRINGING SCATTERED SHOWERS AND GUSTY W TO NW WINDS. 850MB
TEMPERATURES LOOK TO STAY ABOVE FREEZING THROUGH MOST OF THE NIGHT
SO PRECIP SHOULD BE IN THE FORM OF SHOWERS TODAY AND A RAIN/SNOW
MIX THIS EVENING WITH SHOWERS BECOMING ALL SNOW LATE TONIGHT INTO
WEDNESDAY MORNING.

WEDNESDAY...MODELS BRING A REINFORCING SHOT OF COLD AIR INTO THE
REGION. AS THE ASSOCIATED FRONTOGENESIS WORKS ITS WAY SLOWLY
WESTWARD THROUGH THE DAY...IT WILL GENERATE A BAND OF PRECIP THAT
WILL BE ENHANCED BY OROGRAPHICS...SINCE MID LEVEL WINDS WILL BE
NW. MODELS CONTINUE TO WAVER ON AMOUNT AND PLACEMENT OF PRECIP...SO
I BASICALLY BROADBRUSHED LIKELY POPS...WITH A FEW TENTHS OF AN
INCH OF LIQUID EQUIVALENT PRECIP IN SOME AREAS WEST OF ROSEBUD
COUNTY WEDNESDAY AFTERNOON INTO WEDNESDAY NIGHT. WITH REGARDS TO
THE PUSH OF COLDER AIR...MODELS HAVE TRENDED WARMER AT 850
MB...AND THEY HAVE TRENDED TOWARDS SHALLOWER UPSLOPE FLOW ALONG
THE FOOTHILLS...SO THE POTENTIAL FOR HEAVIER SNOW IN THE FOOTHILLS
IS LOOKING LESS LIKELY. STILL...WOULD NOT BE SURPRISED IF A FEW
INCHES ACCUMULATED ON GRASSY SURFACES IN FOOTHILLS REGIONS
WEDNESDAY INTO WEDNESDAY NIGHT. HIGHS WEDNESDAY WILL BE IN THE MID
30S TO MID 40S.

PRECIP TAPERS OFF LATE WEDNESDAY NIGHT ACROSS THE WEST AS WINDS
BECOME SOUTHWESTERLY AND FRONTOLYSIS OCCURS IN ADVANCE OF AN
APPROACHING PACIFIC SYSTEM. THURSDAY...THE PUSH OF SW WINDS MOVES
EASTWARD...GENERATING ISENTROPIC ASCENT AND SOME SHOWERS ACROSS
THE EAST. HIGHS WILL REBOUND INTO THE 40S AND 50S THURSDAY.
THURSDAY NIGHT...CLOUDS INCREASE FROM THE WEST AND THE CHANCE OF
SHOWERS INCREASES ACROSS THE WEST AHEAD OF THE NEXT PACIFIC
SYSTEM. STC

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

UPPER RIDGE OF HIGH PRESSURE WILL BE OVER THE AREA EARLY ON
FRIDAY. THE RIDGE WILL MOVE QUICKLY EASTWARD AS A FAST MOVING
SHORTWAVE TROUGH MOVES IN FROM BRITISH COLUMBIA. THE TROUGH WILL
BRING SHOWERS INTO OUR WESTERN AREAS BY MORNING...SPREADING
EASTWARD DURING THE DAY. BEST FORCING WILL BE OVER THE AREA FRIDAY
NIGHT WITH THE GFS/ECMWF SHOWING STRONG Q VECTOR FORCING PUSHING
THROUGH WITH STRONG JET DIVERGENCE. THE SYSTEM WILL MOVE THROUGH
QUICKLY AND QPF TOTALS WILL BE LIGHT. DRY AND WARMER WEATHER
RETURNING BY SATURDAY AS ANOTHER RIDGE OF HIGH PRESSURE BUILDS
OVER THE NORTHERN PLAINS. THE MILD WEATHER WILL CONTINUE SUNDAY
AND MONDAY. A LONG WAVE TROUGH OF LOW PRESSURE WILL BEGIN MOVING
ONTO THE WEST COAST ON MONDAY...SETTING UP A SOUTHWEST FLOW OF
AIR ALOFT ACROSS SOUTHERN MONTANA. MODELS IN DISAGREEMENT ON THE
DEPTH AND STRENGTH OF THE UPPER TROUGH MOVING ONTO THE WEST COAST
MONDAY. GFS DEVELOPS A CLOSED LOW JUST OFF THE WEST COAST OF
SOUTHERN CALIFORNIA WHILE THE EC BRINGS AN OPEN WAVE INTO THE
WESTERN STATES. DID NOT MAKE ANY CHANGES TO THE LAST TWO PERIODS
OF THE EXTENDED FORECAST DUE TO LARGE MODEL DISCREPANCIES.
RICHMOND

&&

.AVIATION...

A DISTURBANCE MOVING IN FROM THE WEST WILL BRING RAINS AND
SHOWERS TO ALL FLIGHT TERMINALS THIS EVENING. THE RAIN IS EXPECTED
TO TURN TO ALL SNOW AFTER MIDNIGHT. THE SNOW WILL BRING
OCCASIONAL MVFR/IFR CONDITIONS. MOUNTAIN OBSCURATIONS CAN BE
EXPECTED. GUSTY NORTHWEST WINDS WILL CONTINUE THROUGH LATE TONIGHT
AS WELL WITH GUSTS AROUND 30KTS AT TIMES. CHAMBERS

&&

.PRELIMINARY POINT TEMP/POPS...

    WED     THU     FRI     SAT     SUN     MON     TUE
-----------------------------------------------------------
BIL 033/043 029/055 036/063 040/063 042/071 043/068 044/068
    66/W    51/B    12/W    30/B    00/U    00/U    12/W
LVM 029/041 028/055 035/058 036/061 040/067 042/065 038/065
    55/W    51/B    23/W    20/U    00/U    01/B    22/W
HDN 032/043 028/056 034/066 039/064 040/072 041/070 042/069
    77/W    41/B    11/B    30/B    00/U    00/U    11/B
MLS 030/042 027/052 031/062 038/062 040/071 041/068 042/068
    63/W    33/W    12/W    30/B    00/U    00/U    12/W
4BQ 031/043 026/053 030/064 039/062 041/071 041/070 041/071
    66/W    32/W    11/B    30/B    00/U    00/U    11/B
BHK 026/038 024/045 027/056 034/057 035/069 038/066 039/068
    53/W    23/W    21/N    30/B    00/U    00/U    11/B
SHR 031/042 028/054 032/064 038/061 038/069 040/068 039/068
    77/W    41/B    11/B    20/U    00/U    00/U    01/B

&&

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

&&

$$
WEATHER.GOV/BILLINGS



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