Area Forecast Discussion
Issued by NWS Billings, MT

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FXUS65 KBYZ 210922
AFDBYZ

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BILLINGS MT
322 AM MDT MON APR 21 2014

.SHORT TERM...VALID FOR TDY AND TUE...

FOCUS FOR THE SHORT TERM IS ON TUESDAY AFTERNOON AND NIGHT WHEN A
STRONG STORM SYSTEM WILL MOVE INTO THE REGION. AHEAD OF THIS
SYSTEM TODAY LOOKS LIKE A VERY PLEASANT DAY. SOME MID LEVEL CLOUD
COVER WILL PUSH THROUGH THE AREA AS WEAK RIDGING BUILDS ALOFT.
SURFACE TROFFING ALONG AND WEST OF THE FRONT RANGE WILL PULL WINDS
AROUND TO THE SOUTH THEN SOUTHEAST THIS AFTERNOON WHICH WILL HELP
TAKE A FEW DEGREES OFF POTENTIAL HIGH TEMPERATURES FROM MIXING.
OVERALL TEMPERATURES SHOULD BE +/- 3 DEGREES OF THOSE ON
SUNDAY...WITH LESS WIND.

MONDAY NIGHT PACIFIC MOISTURE WILL BEGIN TO INCREASE OVER WESTERN
AREAS AS FLOW ALOFT BENDS TO THE SOUTHWEST IN RESPONSE TO
DEEPENING SYSTEM OFF THE WEST COAST. THIS WILL BE A FAVORABLE
PATTERN FOR PRECIPITATION IN THE MOUNTAINS FROM OVERNIGHT TONIGHT
INTO TUESDAY AFTERNOON. HOWEVER...FOR LOWER ELEVATIONS EAST OF THE
MOUNTAINS THIS PATTER FAVORS MAINLY DRY BUT CLOUDY CONDITIONS.
WITH THE INCREASED CLOUD COVER EXPECT WARM OVERNIGHT TEMPERATURES
IN THE 40S TO AROUND 50 DEGREES.

TUESDAY WILL BE A DYNAMIC DAY AS SEVERAL PIECES OF ENERGY AND
INCREASINGLY DIFFLUENT SOUTHWESTERLY FLOW OVERRUN SOUTHEAST WINDS
AT THE SURFACE. MODELS SHOVE A VERY WARM 850-700MB LAYER OVER THE
AREA FROM THE SOUTH DURING THE DAY WITH BIAS CORRECTED MODEL
TEMPERATURES PUSHING MID TO UPPER 70S FOR HIGHS. THINK THIS IS A
BIT OVERDONE GIVEN THE INCREASED CLOUD COVER BUT KEPT LOWER TO MID
70S IN THE FORECAST OVER CENTRAL AND EASTERN ZONES...WITH
POTENTIALLY RAIN COOLED HIGHS IN THE 60S WEST. CAPE VALUES TUESDAY
ARE NOT TERRIBLY IMPRESSIVE ACROSS THE AREA AT UNDER 500 J/KG.
HOWEVER WITH THE WARM TEMPERATURES AND INHERENT LIFT DUE TO
DIFFLUENT FLOW ALOFT...ALONG WITH GOOD MID LEVEL MOISTURE
ADVECTION AND SOME PACIFIC ENERGY MOVING THROUGH...LIKE THE IDEA
OF ISOLATED TO SCATTERED THUNDERSTORMS EMBEDDED IN MORE WIDESPREAD
SHOWER ACTIVITY. THIS IS ESPECIALLY TRUE DURING THE EVENING HOURS
AS STRONGER ENERGY ARRIVES AND CROSSES THE REGION. INCREASED POPS
OVER WESTERN AND CENTRAL ZONES DURING THE AFTERNOON AND EVENING
HOURS...AND OVERNIGHT FOR ALL LOCATIONS. WHILE THERE WILL BE
SCATTERED TO NUMEROUS SHOWER ACTIVITY AROUND TUESDAY AFTERNOON AND
NIGHT...THE POTENTIAL FOR WIDESPREAD HEAVY PRECIPITATION IS VERY
LOW AT THIS TIME WITH BULK OF THE UPPER STORM SYSTEM STAYING WELL
NORTH OF THE AREA. MOST LOCATIONS WILL SEE A TENTH OF AN INCH OR
LESS BY WEDNESDAY MORNING. COLDER AIR MOVES IN ALOFT AFTER
MIDNIGHT OVER WESTERN ZONES WITH THE POTENTIAL FOR SEVERAL INCHES
OF SNOW IN THE HIGH COUNTRY. CHAMBERS

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

WEDNESDAY AIRMASS WILL SUPPORT CONVECTION THOUGH DRIER AIR BEING
ENTRAINED INTO UPPER LOW OVER NORTHERN MONTANA WILL LIMIT
PRECIPITATION AMOUNTS. FRONTAL POSITION WEDNESDAY MORNING LOOKS TO
BE CLOSE TO THE MONTANA DAKOTA BORDER SO HAVE RAISED PRECIPITATION
CHANCES FOR SOUTHEAST MONTANA. ALSO HAVE RAISED WINDS IN SOUTHEAST
MONTANA AS ANALOG CASES TO THIS PATTERN HAVE HAD STRONG GUSTY
WINDS AND EVEN SOME GUSTS TO 50 MPH. DO NOT HAVE WINDS QUITE THAT
STRONG BUT TRENDING THAT DIRECTION.

AS THE UPPER LOW PROGRESSES INTO THE DAKOTAS ON WEDNESDAY IT WRAPS
SOME BETTER MOISTURE INTO SOUTHERN MONTANA. SHOULD BE A CHILLY DAYMIXING
WILL BE WEAKER AND EVAPORATIVE COOLING KEEPS TEMPERATURES IN THE
50S.

FORECAST FOR FRIDAY THROUGH SUNDAY IS UNCERTAIN BUT A COUPLE OF
TRENDS ARE CLEAR. ANOTHER SYSTEM MOVES TOWARDS THE AREA WITH
A BRIEF PERIOD OF RIDGING ON FRIDAY HELPING BRING A WINDOW OF
QUIETER WEATHER. BY SATURDAY MOISTURE IS INCREASING ACROSS THE
AREA BUT MODELS VARY IN AN IMPORTANT EVOLUTION OF THE NEXT SYSTEM.
GFS DIGS A LOW TOWARDS THE GREAT BASIN BASICALLY SPLITTING THE
NEXT TROUGH. ECMWF STALLS THE NEXT SYSTEM AND ALLOWS A PROLONGED
PERIOD OF UPSLOPE ACTIVITY WITH A BAROCLINIC ZONE ACROSS MONTANA
AND NORTHERN WYOMING. ECMWF HAS BEEN CONSISTENT WITH ITSELF ON
THIS SOLUTION WHICH WOULD BRING A SPRING SNOWSTORM. HAVE TRENDED
COOLER AND WETTER IN THE LATTER PERIODS OF THE EXTENDED FORECAST
WITHOUT COMMITTING TO A RETURN OF WINTER YET. BORSUM.

&&

.AVIATION...

NO RESTRICTIONS TO CEILING OR VISIBILITY THROUGH THE DAY WITH
RELATIVELY LIGHT WINDS. BORSUM

&&

.PRELIMINARY POINT TEMP/POPS...

    TDY TUE     WED     THU     FRI     SAT     SUN
-------------------------------------------------------
BIL 067 046/072 044/057 037/057 036/059 039/059 039/052
    0/U 12/T    64/W    23/W    22/W    23/W    43/W
LVM 066 043/066 038/053 033/059 035/061 037/058 034/053
    0/U 16/T    65/W    33/W    22/W    34/W    43/W
HDN 069 041/075 045/058 034/055 033/061 035/060 036/053
    0/U 02/T    54/T    24/W    22/W    23/W    43/W
MLS 068 044/075 050/061 037/053 032/055 034/057 037/050
    0/U 01/B    44/T    24/W    31/B    23/W    33/W
4BQ 068 043/076 051/062 034/054 032/056 033/059 036/052
    0/U 02/T    33/T    23/W    21/B    23/W    33/W
BHK 064 040/071 049/063 036/050 029/050 030/052 033/045
    0/U 00/N    32/T    23/W    31/E    33/W    44/W
SHR 066 041/073 045/058 037/054 033/061 036/062 036/056
    0/U 02/T    33/T    23/W    22/W    23/W    33/W

&&

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

&&

$$
WEATHER.GOV/BILLINGS



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