Area Forecast Discussion
Issued by NWS Billings, MT

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782
FXUS65 KBYZ 271537
AFDBYZ

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE BILLINGS MT
937 AM MDT WED APR 27 2016

.UPDATE...

VERY PROMINENT DEFORMATION BAND WITH GOOD ISENTROPIC LIFT MOVING
INTO EASTERN COUNTIES THIS MORNING. HAVE UPDATED POPS TO REFLECT
CATEGORICAL PRECIPITATION IN THE EAST THROUGH MUCH OF THE DAY.
ALSO ADDED SOME ACCUMULATING SNOW TO EASTERN ZONES OF AROUND AN
INCH OR TWO. BT

&&

.SHORT TERM...VALID FOR TDY AND THU...

COMPUTER MODELS CONTINUE TO SHOW GOOD AGREEMENT WITH THE OVERALL
FORECAST THROUGH THE FIRST 48 HOURS OR SO...THEN DIVERGE AS VERY
COMPLEX PATTERN REMAINS IN PLACE THROUGH THE REST OF THE WEEK. THE
GFS AND ECMWF DID PRETTY WELL WITH PRECIPITATION PLACEMENT
OVERNIGHT...BUT THE NAM AND SREF SEEMED TO MISS PLACEMENT TOO FAR
SOUTH AND EAST. AS A RESULT WILL LEAN ON THE GFS AND ECMWF AND THE
ENSEMBLES FOR THIS FORECAST PACKAGE.

BROAD UPPER LEVEL TROF REMAINS IN PLACE ACROSS THE WESTERN HALF OF
THE CONUS THIS MORNING. MAIN UPPER LEVEL LOW PRESSURE SYSTEM
WITHIN THE TROF IS CURRENTLY CENTERED OVER WESTERN
KANSAS...HOWEVER A PIECE OF THIS SYSTEM BROKE OFF OF THE MAIN LOW
YESTERDAY AND HAS SPUN NORTHWARD INTO NORTHEAST WYOMING. THIS
SMALLER LOW IS HELPING TO KEEP THE MOISTURE FEED AND NORTHEASTERLY
WINDS GOING OVER THE AREA TODAY. AREA OF QG FORCING ALOFT
COMBINING WITH THIS VORTICITY CENTER HAS BROUGHT WIDESPREAD LIGHT
PRECIPITATION TO SC MONTANA/NC WYOMING OVERNIGHT WHILE SOUTHEAST
MONTANA HAS GOTTEN A BIT OF A BREAK. AS WE GO THROUGH THE MORNING
THE FORCING THAT BROUGHT THE PRECIPITATION TO SC MT WILL WEAKEN
AND PRECIPITATION WILL DIMINISH. OVER SE MT FLOW OF MOISTURE AND
ENERGY AROUND THE UPPER LOWS WILL INCREASE BRINGING PRECIPITATION
BACK. AS THE DAY PROGRESSES FORCING WILL SPREAD SLOWLY WESTWARD
INCREASING PRECIPITATION CHANCES...AND BY THIS EVENING SHOULD SEE
A GOOD CHANCE OF PRECIPITATION AS FAR WEST AS A RYEGATE TO
COLUMBUS LINE. PRECIPITATION AMOUNTS WILL BE LIGHT OVER SC MT/NC
WY AT GENERALLY LESS THAN A TENTH OF AN INCH THROUGH TONIGHT. FOR
SE MT HEAVIER ACCUMULATIONS AROUND A QUARTER OF AN INCH SEEM
REASONABLE...ESPECIALLY EAST OF A MILES CITY TO BROADUS LINE.
EXPECT A MIX OF PRECIPITATION TYPES TODAY WITH SNOW POTENTIAL
DIMINISHING THIS AFTERNOON AND INCREASING AGAIN THIS AFTERNOON.
ANY SNOW ACCUMULATIONS WILL BE LIGHT AND MAINLY OVER THE HIGHER
HILLS OF SE MT AS HAS BEEN THE CASE THE PAST SEVERAL DAYS.
TEMPERATURES TODAY WILL BE SIMILAR TO THE PAST FEW DAYS...MAINLY
IN THE 40S.

FOR TOMORROW...FORCING FOR PRECIPITATION IS STRONGEST IN THE
MORNING...THEN DECREASES DURING THE AFTERNOON HOURS. BY THURSDAY
EVENING A FEW AREAS OF DRIZZLE MAY PERSIST BUT ACCUMULATING
PRECIPITATION WILL BE MAINLY OVER FOR A DAY OR TWO. TEMPERATURES
THURSDAY WILL BE MAINLY IN THE 40S ONCE AGAIN...BUT WARMER
TEMPERATURES ARRIVE FOR FRIDAY. CHAMBERS

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


CONTINUED TO JUST BLEND IN THE LATEST MODEL CONSENSUS. MODELS
CONTINUE TO SHOW A TROUGH MOVING ACROSS THE ROCKIES ON FRIDAY. AS
IT DOES...WITH MID LEVEL MOISTURE STILL IN PLACE...A CHANCE FOR
RAIN WILL REMAIN. THE MODELS ARE NOT SHOWING AS MUCH OF A BLOCKING
PATTERN OVER THE MIDWEST. HOWEVER...THE MODELS ARE NOW SHOWING THE
NEXT SYSTEM DROPPING IN RIGHT BEHIND THE FRIDAY TROUGH. AS IT
DOES...THE TWO SYSTEM WILL BEGIN TO PINWHEEL. THIS WILL KEEP THE
RAIN CHANCES GOING THROUGH THE WEEKEND. HAVE KEPT THEM LOW BUT
STILL A CHANCE.

THESE SYSTEMS DO NO PROGRESS AS QUICKLY AS THE MODELS HAD
PREVIOUSLY BEEN ADVERTISING...SO THE START TO THE WEEK WILL NOT BE
A DRY AS PREVIOUSLY EXPECTED. THE RIDGE WILL FINALLY WORK IN BUT
IT WILL NOT BE UNTIL WEDNESDAY. TEMPERATURES WILL CONTINUE TO
INCREASE...BUT THE WARMUP WILL BE A BIT DELAYED WITH THE CONTINUED
PRECIP CHANCES BEFORE THE LOWS MOVE OUT. REIMER

&&

.AVIATION...


SCATTERED RAIN AND SNOW WILL CONTINUE TO DECREASE FLIGHT
CONDITIONS THROUGH THE MORNING. LOCALIZED IFR CONDITIONS ARE
POSSIBLE. CONDITIONS SHOULD IMPROVE TO VFR TO MVFR FOR A TIME
ACROSS CENTERAL AND WESTERN AREAS LATER THIS MORNING AND
AFTERNOON AS ONE WAVE OF PRECIPITATION DECREASES. HOWEVER...MORE
RAIN AND SNOW WILL SPREAD FROM EAST TO WEST THROUGH THE DAY AND
INTO THE EVENING CAUSING CONDITIONS TO DETERIORATE TO MVFR TO
POSSIBLY IFR. REIMER/STP

&&

.PRELIMINARY POINT TEMP/POPS...

    TDY THU     FRI     SAT     SUN     MON     TUE
-------------------------------------------------------
BIL 045 034/046 033/055 037/055 040/056 039/060 040/065
    6/O 53/O    32/W    23/W    44/W    22/W    11/B
LVM 047 030/048 029/058 035/057 036/055 035/059 036/066
    4/O 33/O    22/W    23/W    44/W    22/W    22/W
HDN 043 034/048 031/057 035/054 036/056 036/061 037/066
    4/O 65/O    32/W    23/W    44/W    22/W    11/B
MLS 042 033/048 033/055 037/053 039/057 038/062 039/065
    8/O 75/O    32/W    23/W    43/W    11/B    11/U
4BQ 041 031/045 029/053 035/049 036/053 036/059 037/063
    7/O 75/O    22/W    34/W    44/W    22/W    11/B
BHK 040 030/045 030/051 034/051 035/055 035/059 036/062
    +/O 85/O    32/W    24/W    43/W    11/B    11/U
SHR 042 031/045 028/053 033/050 034/052 034/056 034/061
    6/O 64/O    32/W    24/W    44/W    22/W    22/W

&&

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

&&

$$
WEATHER.GOV/BILLINGS



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