Area Forecast Discussion
Issued by NWS Billings, MT

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FXUS65 KBYZ 220841
AFDBYZ

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BILLINGS MT
241 AM MDT WED APR 22 2015

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

SHORT TERM PROGGS AGREE THAT WE SHOULD BE TRENDING TOWARD A
LITTLE MORE ACTIVE WEATHER THE NEXT COUPLE OF DAYS. THE RIDGE AXIS
CURRENTLY OVER THE NORTHERN ROCKIES WILL BEGIN TO BREAK DOWN LATE
TODAY AS A TROUGH TRACKS ACROSS THE CANADIAN BORDER. IN THE
MEANTIME...THERE APPEARS TO BE SOME MONSOON TYPE INFLUENCE FROM AN
UPPER LOW OVER THE DESERT SOUTHWEST SHEDDING MOISTURE TOWARD THE
NORTHERN ROCKIES.  MOST OF THE SHORT WAVE ENERGY WILL BE NORTH OF
OUR FORECAST AREA...BUT THE ASSOCIATED FRONT WILL BE DRAGGED OVER
OUR REGION. SO WE HAVE SOME MOISTURE MOVING TOWARD US AND AT
LEAST A WEAK LIFTING MECHANISM...AND COMBINED WITH SOME DIURNAL
INSTABILITY SHOULD RESULT IN SOME SHOWERS OVER THE WESTERN
ZONES...POSSIBLY INCLUDING SOME THUNDER. A FEW MOUNTAIN SHOWERS
MAY LINGER LATE INTO THURSDAY MORNING.

FOR THE REMAINDER OF THURSDAY...SOUTHWEST FLOW ALOFT AND A WEAK
THETA-E RIDGE OVER THE SOUTHERN SECTIONS OF OUR FORECAST AREA
SHOULD RESULT IN SOME ISOLATED TO SCATTERED CONVECTION.
HOWEVER...I DID CUT BACK ON THE POPS FOR OUR NORTHERN ZONES IN
THIS TIME FRAME AS THE BEST INSTABILITY IS PROGGED TO BE OVER THE
MONTANA/WYOMING LINE.

LOOK FOR TEMPERATURES TO BE MILD TODAY AND TOMORROW AS THE FLOW
REMAINS CUT OFF FROM ANY COLDER AIR. BT

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

BETTER MODEL AGREEMENT INTO THE WEEKEND FOR THIS SET OF RUNS WITH
THE UKMET SHOWING UP AS AN OUTLIER. FRIDAY FLOW ALOFT BEGINS TO
SLOWLY TURN SOUTHWESTERLY IN ADVANCE OF AN UPPER LOW MOVING INTO
BC. THIS SYSTEM FILLS AND BECOMES A SPLITTING LONGWAVE TROUGH WITH
THE STRONGER PORTION MOVING INTO THE GREAT BASIN ON SATURDAY AND
BY SUNDAY WEAK FLOW IS PRESENT OVER MONTANA WITH A DEVELOPING LOW
OVER THE FOUR CORNERS REGION HAVING A BIGGER INFLUENCE OVER
WYOMING. RIDGING FOLLOWS THIS SYSTEM SO THE PRECIPITATION IMPACTS
SHOULD BE LIMITED TO THE WEEKEND WITH A WARMING AND DRYING PATTERN
NEXT WEEK.

DETAILS TO THE MODEL SOLUTIONS ARE CAUSING LESS CONFIDENCE FOR HOW
MUCH RAINFALL WILL OCCUR OVER THE WEEKEND...AND WHERE. IT WILL BE
UNSETTLED AND COOLER WITH DEEPER MOISTURE OVER THE WEEKEND AND
TROUGHINESS...BUT IT DOES NOT LOOK LIKE DEEP INSTABILITY. BEST
ROUND OF INSTABILITY DOES LOOK LIKE SATURDAY AS A FRONT PUSHES
THROUGH WITH BEST CHANCES IN SOUTH CENTRAL MONTANA EXTENDING
NORTHWARD. MODELS THEN AGREE IN A SECOND AREA OF MOISTURE OVER
SOUTHEAST MONTANA SATURDAY NIGHT AND SUNDAY WITH SURFACE LOW
PRESSURE WINDING UP IN THE LEE OF THE COLORADO ROCKIES WITH PRECIP
FILLING IN OVER SOUTHEAST MONTANA IN AN INVERTED SURFACE TROUGH.
THIS SHOULD BE AIDED BY BETTER MOISTURE TRANSPORT INTO THE REGION.
HAVE RAISED POPS IN FOREMENTIONED PERIODS TO REFLECT INCREASING
CONFIDENCE DUE TO A MORE CONSISTENT PRESENTATION ON THE MODELS.

TEMPERATURES WILL BE COOLER OVER THE WEEKEND WITH BETTER CLOUD
COVER AND SOME EVAPORATIVE COOLING. BORSUM
&&

.AVIATION...

LIGHT WINDS WILL CONTINUE WITH MOSTLY CLEAR SKIES THROUGH EARLY
AFTERNOON. EXPECT CUMULUS DEVELOPMENT OVER THE MOUNTAINS WITH SOME
SHOWERS REACHING ADJACENT PLAINS BUT VFR EXPECTED TO PREVAIL.
BORSUM
&&

.PRELIMINARY POINT TEMP/POPS...

    TDY THU     FRI     SAT     SUN     MON     TUE
-------------------------------------------------------
BIL 072 046/067 044/068 044/062 042/062 041/064 042/073
    0/B 02/T    23/W    44/W    32/W    21/B    11/B
LVM 072 039/067 038/066 038/060 037/058 035/062 038/072
    2/T 24/T    34/W    55/W    43/W    21/B    11/B
HDN 074 040/069 039/071 039/064 038/063 038/065 038/074
    0/B 01/B    22/W    24/W    33/W    21/B    11/B
MLS 067 038/069 038/070 040/065 039/063 038/065 039/071
    0/B 01/B    11/B    25/W    53/W    21/B    11/B
4BQ 067 037/071 038/070 041/064 040/060 040/063 039/071
    0/B 02/T    22/W    25/W    64/W    21/N    11/N
BHK 060 032/065 034/064 036/062 037/060 035/062 034/067
    0/U 01/N    12/W    24/W    54/W    21/B    11/N
SHR 069 039/067 039/067 039/062 038/057 037/060 037/070
    0/B 02/T    23/W    23/W    44/W    21/N    11/N

&&

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

&&

$$
WEATHER.GOV/BILLINGS



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