Area Forecast Discussion
Issued by NWS Billings, MT

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000
FXUS65 KBYZ 231706
AFDBYZ

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE BILLINGS MT
1006 AM MST SUN NOV 23 2014

.UPDATE...
OVERALL THEME OF THE DAY ONE FORECAST IN GOOD SHAPE. UPPER TROUGH
WAS WORKING THROUGH EASTERN MONTANA WITH NORTHERLY FLOW THIS
MORNING OVER THE FORECAST AREA. WINDS WERE STILL GUSTING TO 37MPH
AT BAKER AND 38MPH AT MILES CITY. SURFACE PRESSURE GRADIENT WAS
RELAXING AND WILL CONTINUE TO DO SO...SO WINDS SHOULD BACK OFF
THIS AFTERNOON. RAISED HIGH TEMPERATURES A COUPLE OF DEGREES IN
PLACES WITH A WARM START. ALSO TRIMMED POPS ON THE WESTERN EDGE
THIS MORNING AND THIS AFTERNOON BASED ON SATELLITE AND RADAR
COVERAGE. TWH

&&

.SHORT TERM...VALID FOR TDY AND MON...

MADE MINIMAL CHANGES TO THE INHERITED FORECAST ONCE AGAIN THIS
MORNING...AS ACTIVE WEATHER REMAINS ON TAP FOR THE SHORT TERM.
WINDY WEATHER WILL BE MAIN CONCERN...ALTHOUGH MOUNTAIN SNOW...AND
ISOLATED TO SCATTERED SHOWERS ARE EXPECTED THROUGHOUT THE PERIOD.

STRONG AND GUSTY WINDS CONTINUE EAST OF BILLINGS THIS
MORNING...INCLUDING MILES CITY AND BAKER. WINDS HAVE GUSTED AROUND
40 MPH THROUGH THE NIGHT...AND EXPECT TO SIMILAR WINDS TO PERSIST
THROUGH THE DAY IN THOSE AREAS. ADDITIONALLY A SHORTWAVE CROSSING
THAT REGION WILL CONTINUE TO BRING SHOWERS TO EASTERN MONTANA
THROUGH THIS MORNING. PRECIP POTENTIAL WILL TAPER OFF QUICKLY IN
THE EAST THIS AFTERNOON.

MODELS CONTINUE TO SUPPORT WINDS INCREASING AGAIN AT LIVINGSTON
AND NYE TONIGHT. GRADIENTS AND LOCAL GUIDANCE DO NOT LOOK
SUFFICIENT TO SUPPORT HIGHLIGHTS AT THIS...BUT COULD BE CLOSE.
WINDS TAPER OFF SOME FOR MONDAY...BUT CONDITIONS REMAIN BREEZY
THROUGH THE DAY. WINDS WILL BECOME EVEN STRONGER AT LIVINGSTON AND
NYE MONDAY NIGHT...AS LEE TROF DEEPENS AND SFC GRADIENT TIGHTENS
OVER THE WEST. MODELS AND LOCAL GUIDANCE LOOKS MUCH BETTER FOR
THIS ROUND OF WINDS...AND MAY NEED A HIGHLIGHT IF MODELS REMAIN
CONSISTENT.

EXPECT TEMPS TO BE COOLER TODAY AND TOMORROW FOLLOWING THE COLD
FRONTAL PASSAGE YESTERDAY. DO EXPECT TEMPS TO BE SLIGHTLY WARMER
MONDAY...AS DOWNSLOPE FLOW BRINGS SOME WARMING TO THE REGION. DID
BUMP TEMPS UP SLIGHTLY FOR MONDAY.

AS FOR PRECIP ACROSS THE REGION. UNSETTLED NORTHWEST FLOW
PERSISTS THROUGH THE PERIOD...BRINGING SEVERAL SHORTWAVES THROUGH
THE REGION. HAVE KEPT SCATTERED POPS IN THE PLAINS...WITH HIGHER
POPS IN WESTERN MOUNTAINS TODAY THROUGH MONDAY. A SHORTWAVE WILL
COMPLETE PASSAGE ACROSS THE EAST THIS MORNING...WITH ANOTHER ON
TAP TO CROSS THE REGION TONIGHT AND INTO MONDAY. THERE APPEARS TO
BE A SHORT BREAK MONDAY AFTERNOON/EVENING FOR THE PLAINS
REGIONS...BUT ANOTHER DISTURBANCE WILL SLIDE THROUGH THE FLOW
MONDAY NIGHT FOR ANOTHER CHANCE OF SHOWERS ACROSS THE REGION. AAG

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

MODEL CONFIDENCE CONTINUES TO BE A STRUGGLE WITH ENSEMBLE
TEMPERATURE GUIDANCE SHOWING A 26 DEGREE SPREAD IN HIGH
TEMPERATURES FOR BILLINGS FROM 48 TO 22...AND 33 DEGREES SPREAD
FOR THANKSGIVING. ECMWF HAS SHOWN A BIT MORE RUN TO RUN
CONSISTENCY AND IS SHOWING A COOLER TREND SO CONFIDENCE IS STILL
WEAK BUT HAVE SEEN ENOUGH TO PROJECT OUT A 3 DAY SCENARIO TUESDAY
THROUGH THURSDAY. THIS SOLUTION WILL LARGELY ECHO THE ECMWF FROM
11/23 AT 00Z.

TUESDAY MORNING AN ONGOING DOWNSLOPE WIND EVENT WILL BE IMPACTING
MOST OF THE WESTERN ZONES INCLUDING THE RED LODGE AREA. CONTINUE
TO BE CONCERNED ABOUT THE MAGNITUDE OF THE WINDS POSSIBLE WITH
THIS EVENT. PACIFIC FRONT MOVES THROUGH THE AREA DURING THE DAY
BRINGING INCREASING MOISTURE AND HELPING COOL TEMPERATURES. SOME
OF THIS COOLING EVIDENT ON THE ECMWF LIKELY DUE TO EVAPORATIVE
COOLING OF THE LOWER LEVELS OF THE ATMOSPHERE SO HARD TO INTERPRET
WHERE THE LEADING EDGE OF THE COLD FRONT REALLY WILL BE.
REGARDLESS OF AFTERNOON TEMPERATURES A SECONDARY PUSH OF COLDER
AIR TUESDAY NIGHT COMBINES WITH THE MOISTURE TO MAKE SURE SNOW IS
FALLING OVERNIGHT. ECMWF IS SUFFICIENTLY DEEP WITH THE COLD AIR TO
CUT OFF THE DOWNSLOPE WIND EVENT BY LATE TUESDAY AND EARLY LOOK AT
THE 06Z GFS APPEARS TO SUPPORT THIS SOLUTION.

NOW THE TRICKY PART IS WHEN DOES THE COLD AIR BEGIN TO RETREAT AND
THE DOWNSLOPE WINDS RETURN. ECMWF KEEPS COLD IN ALL DAY WHEREAS
GFS BEGINS TO LIFT THE SURFACE BOUNDARY AS FAR NORTHEAST AS
A SHERIDAN TO BILLINGS TO RYEGATE LINE BY 00Z. WITH THE AMOUNT OF
MOISTURE STREAMING ALONG THIS BOUNDARY DRYING PERIODS OF DECENT
PRECIPITATION THERE IS POTENTIAL FOR ACCUMULATING SNOWFALL DURING
THE DAY...AND THE SLOPE OF THE BOUNDARY WILL CAUSE SIGNIFICANT
DIFFERENCES IN INTENSITY OVER A SHORT DISTANCE. AGAIN STICKING
WITH ECMWF SOLUTION AND EXPECTING SNOW FOR MOST OF THE AREA
THOUGH LIVINGSTON COULD STAY WARM ENOUGH TO BE A MIX. AT THIS
POINT THE MAJOR THREAT TO TRAVEL ALONG I90 BETWEEN BILLINGS AND
BIG TIMBER TO SHERIDAN GOING THE OTHER WAY AND I94 TO HYSHAM LOOKS
TO BE PERIODS OF MODERATE SNOWFALL.

WEDNESDAY NIGHT AND THURSDAY FOR MOST OF THE AREA SNOW CONTINUES
WITH THE DEEP MOISTURE OVERRUNNING THE COLD AIRMASS AND ECMWF IS
SHOWING PROJECTED AMOUNTS SIMILAR TO LAST NIGHTS GFS. ECMWF ALSO
IS RAMMING IN EVEN COLDER AIR WHILE THE GFS IS SENDING THE
SURFACE TROUGH NORTHEAST OF SOUTH CENTRAL MONTANA ALLOWING MILD
AIR TO ARRIVE. STICKING WITH ECMWF FOR THE REMAINDER OF THE
EXTENDED WHICH SLOWS DOWN SNOW ON FRIDAY BUT KEEPS US CHILLY IN
THE 20S. HOW COLD WE STAY LIKELY IS DEPENDENT ON SNOW COVER AND
GIVEN ALL THE OTHER UNCERTAINTY JUST HAVE A MODEL BLEND FOR NEXT
WEEKEND TEMPERATURES BUT THEY ARE COLDER THAN OPERATIONAL GFS.

IT DOES APPEAR THAT NEXT SUNDAY COULD BE IMPACTED BY ANOTHER SNOW
STORM SO TRAVELER WILL NEED TO MONITOR FORECASTS CLOSELY. BORSUM

&&

.AVIATION...

STRONG NORTHWEST WINDS EXPECTED FOR SOUTHEAST MONTANA UNTIL EARLY
AFTERNOON WITH GUSTS TO 35KT INCLUDING KMLS...BUT WESTERN AREAS
SHOULD ONLY SEE WIND GUSTS TO 25KT TODAY. A FEW SHOWERS ARE
EXPECTED FROM KMLS TO KBHK BUT STILL MOSTLY VFR CONDITIONS
SHOULD PREVAIL. THE MOUNTAINS WILL BE MOSTLY OBSCURED DUE TO
OCCASIONAL SNOW SHOWERS. WINDS WILL SUBSIDE IN SOUTHEAST MONTANA
THIS AFTERNOON BUT INCREASE AT KLVM THIS EVENING. BORSUM/TWH

&&

.PRELIMINARY POINT TEMP/POPS...

    TDY MON     TUE     WED     THU     FRI     SAT
-------------------------------------------------------
BIL 043 025/043 027/040 028/037 021/034 019/028 009/027
    2/N 21/N    24/W    65/J    32/J    22/W    22/J
LVM 038 023/038 024/037 031/042 026/040 024/035 017/036
    2/W 31/N    26/J    73/W    33/J    22/W    22/J
HDN 042 022/041 022/040 023/036 018/034 016/030 008/028
    3/N 23/J    24/J    65/J    32/J    12/W    22/J
MLS 038 016/036 020/036 021/028 011/027 010/022 002/021
    4/W 22/J    23/J    45/J    43/J    22/W    22/J
4BQ 037 017/036 019/036 021/031 015/030 015/028 007/024
    3/W 23/J    23/J    45/J    32/J    11/B    21/B
BHK 029 011/029 018/034 018/023 008/022 008/021 003/017
    5/J 22/J    13/J    44/J    42/J    22/W    22/J
SHR 041 019/038 019/039 023/037 020/037 017/034 012/032
    4/N 22/J    24/J    54/J    22/J    11/B    11/B

&&

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

&&

$$
WEATHER.GOV/BILLINGS



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