Area Forecast Discussion
Issued by NWS Billings, MT

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000
FXUS65 KBYZ 051600
AFDBYZ

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE BILLINGS MT
1000 AM MDT THU MAY 5 2016

.UPDATE...

LOOKS LIKE ENOUGH MID LEVEL MOISTURE AND CLOUD COVER TO HOLD
TEMPERATURES DOWN SEVERAL DEGREES OFF OF PREVIOUS FORECAST HIGHS
OVER CENTRAL AND WESTERN ZONES. REMOVED MENTION OF RECORD HIGH FOR
LIVINGSTON AT THIS POINT AS HIGHS SHOULD STAY IN THE LOWER 80S
THERE. BILLINGS WILL BE CLOSE TO THE 84 DEGREE RECORD. KEPT A
MENTION OF ISOLATED THUNDERSTORMS WEST OF BILLINGS FROM LATE THIS
AFTERNOON INTO THIS EVENING...TRANSITIONING TO A CHANCE OF SHOWERS
OVERNIGHT AS COLD FRONT APPROACHES. COLD FRONT ON TRACK TO ARRIVE
AROUND SUNRISE TOMORROW MORNING. MODELS STILL BULLISH ON
PRECIPITATION CHANCES OVER SOUTHERN HALF OF THE FORECAST AREA. GFS
GOING BONKERS OVER THE MOUNTAINS AND FOOTHILLS...PARTICULARLY THE
SHERIDAN FOOTHILLS. WILL BE TAKING A CLOSE LOOK AT PRECIPITATION
AMOUNTS WITH AFTERNOON FORECAST PACKAGE TO SEE IF WE NEED TO
UPGRADE QPF AMOUNTS. CHAMBERS

&&

.SHORT TERM...VALID FOR TDY AND FRI...

RECORD HIGH TEMPERATURES EXPECTED TODAY AS UPPER LEVEL HIGH
PRESSURE BEGINS TO BREAK DOWN AND THIS SUPPORTS INCREASING MIXING.
GUIDANCE SHOWS 700MB AND 850MB TEMPERATURES A DEGREE WARMER SO
A COUPLE OF DEGREES WARMER THAN WEDNESDAY SEEMS REASONABLE. ONLY
DRAWBACK IS CLOUD COVER CURRENTLY OVER THE WESTERN HALF OF MONTANA
AND WYOMING BUT THIS SHOULD PUSH EAST BY LATE MORNING ALLOWING
SUNSHINE TO CONTRIBUTE TO THE HEATING PROCESS. CONVECTIVE ALLOWING
SHORT TERM MODELS SHOW SOME HIGH ELEVATION CONVECTION TODAY BUT
ITS PRETTY LIMITED SO HAVE LOWERED POPS OVER THE ADJACENT
FOOTHILLS A BIT.

COLD FRONT PUSHES THROUGH THE AREA TONIGHT AND GFS IS BY FAR THE
MOST AGGRESSIVE MODEL PRODUCING MOISTURE WITH THIS SYSTEM WITH
PRECIPITATION LAGGING BEHIND THE FRONT. WRF RUNS AND ECMWF REALLY
SHOW A STRONG DEPENDENCE ON OROGRAPHICS TO HELP FOSTER CONVECTIVE
DEVELOPMENT. LOWERED QPF AMOUNTS AND DECREASED CHANCES FOR SHOWERS
AND THUNDERSTORMS OVER THE PLAINS FRIDAY AND FRIDAY NIGHT BUT KEPT
LIKELY SHOWERS FOR THE FOOTHILLS...MOUNTAINS AND SHERIDAN COUNTY.
FRIDAY WILL BE MUCH COOLER BEHIND THE FRONT BUT MODELS DISAGREEING
ON THE AMOUNT OF DIURNAL WARMING AND AGAIN LEANING AWAY FROM THE
OPERATIONAL GFS.

LOOK AT RIVER GAGES RESPONSE TO THE SURGE IN TEMPERATURES HAS
BEEN SLOW AND SUSPECT THAT SNOW BELOW 8000 FEET LARGELY ALREADY
CAME OUT AND HIGH ELEVATION SNOW IS JUST NOT PRODUCING ENOUGH
WATER TO CAUSE DRAMATIC RISES. A MUCH STRONGER JUMP SHOULD BE
EXPECTED TODAY AND FRIDAY AS MULTIPLE DAYS WITH LOW TEMPERATURES
AROUND 40 AT 9000 FT MSL IS HAVING AN IMPACT AND SEEING NUMEROUS
SNOTEL SITES WHICH HAVE LOST CLOSE TO AN INCH OF SNOW WATER
EQUIVALENT IN A DAY. BORSUM

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


MODELS CONTINUE TO BE IN GOOD AGREEMENT FOR THE WEEKEND IN
KEEPING AN UPPER LOW AND ASSOCIATED DYNAMICS JUST TO THE SOUTH OF
MONTANA ACROSS CENTRAL WYOMING. AS A RESULT...THE HEAVIEST
PRECIPITATION LOOKS TO STAY TO THE SOUTH OF OUR FORECAST AREA. IN
ANY CASE...WE WILL CONTINUE WITH A CHANCE FOR SHOWERS SATURDAY AND
SUNDAY ALONG AND SOUTH OF A HARLOWTON-BILLINGS-BROADUS LINE. A
LARGER UPPER LOW AND TROUGH DROP SOUTH OUT OF CANADA INTO THE
PACIFIC NORTHWEST SUNDAY NIGHT THEN ACROSS IDAHO AND WYOMING
MONDAY AND TUESDAY AND INTO SOUTH DAKOTA WEDNESDAY INTO THURSDAY.
THIS LOW WILL BRING A MOIST EASTERLY UPSLOPE FLOW ACROSS THE
FORECAST AREA ALONG WITH A GOOD DEAL OF SHOWER ACTIVITY OR THE
POSSIBILITY FOR A GENERAL STEADY RAIN AT TIMES. ALTHOUGH THIS IS
PRETTY FAR OUT IN TIME FOR ANY DETAILS. TEMPERATURES LOOK TO BE
ABOVE NORMAL FOR THE WEEKEND BEFORE RETURNING TO NORMAL VALUES
WITH READINGS IN THE LOWER TO MIDDLE 60S FOR NEXT WEEK. HOOLEY


&&

.AVIATION...


VFR CONDITIONS WILL PREVAIL TODAY WITH NO AVIATION HAZARDS
EXPECTED. HOOLEY

&&

.PRELIMINARY POINT TEMP/POPS...

    TDY FRI     SAT     SUN     MON     TUE     WED
-------------------------------------------------------
BIL 085 055/065 048/065 046/071 048/065 044/060 041/060
    0/B 23/T    33/W    22/W    24/T    44/W    43/W
LVM 080 047/060 042/062 040/069 042/063 039/059 036/056
    2/T 25/T    44/W    22/T    44/T    44/W    43/W
HDN 086 048/069 042/068 041/071 041/068 041/061 038/062
    0/B 12/T    43/W    22/W    24/T    44/W    43/W
MLS 089 056/074 046/072 046/074 047/071 046/060 042/064
    0/U 12/T    21/U    01/U    13/T    34/W    43/W
4BQ 087 051/076 045/067 042/069 043/069 043/061 040/062
    0/U 12/T    52/W    12/T    23/T    34/W    43/W
BHK 086 052/074 041/071 041/071 043/068 042/059 038/061
    0/U 12/T    20/U    01/U    13/T    34/W    43/W
SHR 083 045/066 041/062 040/066 039/063 038/058 037/056
    0/B 13/T    66/W    33/T    24/T    44/W    43/W

&&

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

&&

$$
WEATHER.GOV/BILLINGS


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