Area Forecast Discussion
Issued by NWS Billings, MT

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000
FXUS65 KBYZ 140957
AFDBYZ

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BILLINGS MT
357 AM MDT TUE APR 14 2015

.SHORT TERM...VALID FOR TDY AND WED...

VERY DYNAMIC WEATHER THE NEXT FEW DAYS. ON THE FRONT SIDE OF AN
APPROACHING COLD FRONT...HIGH TEMPERATURES WILL SOAR INTO THE 70S
AND 80S ACROSS THE FORECAST AREA TODAY. SOUTH TO SOUTHWEST WINDS
WILL MIX TO 15 TO 30 MPH...WITH GUSTS TO 40 MPH. A STRONG COLD
FRONT WILL MARCH IN FROM THE WEST AND CAUSE A DRAMATIC WIND SHIFT
LATE THIS AFTERNOON AND EARLY THIS EVENING. THIS FRONT WILL ALSO
TRIGGER ISOLATED THUNDERSTORMS. ALL OF THESE FACTORS WILL COMBINE
FOR A CRITICAL FIRE WEATHER DAY. RED FLAG LOOKS IN GOOD SHAPE. AM
A BIT CONCERNED THAT INCREASING CLOUDS OVER THE WEST MAY LIMIT
SOME OF THE MIXING AND HUMIDITY DROP...BUT WILL BE CLOSE.

HIGH TEMPERATURES TODAY WILL BE NEAR RECORD FOR SHERIDAN AND
MILES CITY WITH FORECAST HIGHS IN THE LOWER TO MID 80S. THESE WARM
TEMPERATURES WILL BE A DISTANT MEMORY ON WEDNESDAY AS A POWERFUL
COLD FRONT WILL PUT AN END TO THE MILD TEMPERATURES FOR A COUPLE
OF DAYS. CERTAINLY...HIGHS IN THE 80S ARE NOT SEEN FOR A WHILE
AFTER THE FRONT MOVES THROUGH.

THE ABOVE MENTIONED COLD FRONT WILL PUSH INTO THE WEST LATE THIS
AFTERNOON...CENTRAL ZONES EARLY THIS EVENING AND THE EAST BY MID
EVENING. STRONG COLD ADVECTION AND SURFACE PRESSURE RISES OF 2MB
AN HOUR WILL MAKE THIS FRONT BLAST THROUGH LOUDLY. GIVEN THE FACT
THAT THE LOW LEVELS WILL BE STARTING OUT SO LOW...AND THERE WILL
BE SOME LOW LEVEL MOISTURE LOADING ON THE FRONT SIDE OF THE
FRONT...SHOULD SEE WIDESPREAD WIND GUSTS OF 50MPH+ AS IT RIPS
THROUGH. WOULD NOT BE SURPRISED TO SEE SOME GUSTS HIGHER THAN THAT
OVER WESTERN AND CENTRAL ZONES. BUMPED WINDS UP FOR THE FRONT AND
WILL MENTION IN THE HWO AND RED FLAG WARNING.

SHOWERS WILL SPREAD FROM WEST TO EAST DURING THE EVENING. THE
UPPER TROUGH DRIVING THE COLD FRONT WAS CUTTING OFF FARTHER WEST
AND SOUTH AND THUS MOVING A LITTLE SLOWER WITH ASCENT. THUS...THE
PRECIPITATION WAS DELAYED...ESPECIALLY EAST OF BILLINGS. HAVE
TRIMMED POPS BACK A LITTLE IN THESE LOCATIONS TONIGHT. RAISED POPS
WEST AND CENTRAL AS THE GFS AND ECMWF WERE CONSISTENT ON SPREADING
QPF IN. THE WRF WAS THE OUTLIER AND DISCOUNTED AS BEING ODDLY DRY
GIVEN THE UPPER DIVERGENCE PRESENT WITH THIS SYSTEM. WILL NEED TO
BE WATCHED THOUGH. IF THE NAM VERIFIES...THE SYSTEM WILL BE DRY
FOR CENTRAL ZONES WITH NOT MUCH HAPPENING ALONG THE FOOTHILLS.

WENT WITH A GFS/ECMWF BLEND FOR POPS AND QPF FORECAST TONIGHT
INTO WEDNESDAY NIGHT. THE GFS WAS VERY HIGH WITH QPF TOTALS AND
FELL IT WAS OVER DONE...ESPECIALLY CONSIDERING HOW DRY THE LOW
LEVELS WILL BE TO START OFF. THAT BEING SAID...DIFFLUENCE ALOFT
AND NORTHERLY FLOW DEVELOPING AT 700MB LENDS ME TO BELIEVE IN HIGH
POPS. HARD TO DISCOUNT ALL THE QPF BEING THROWN OUT BY THE GFS AND
EVEN IF YOU LEAN SOLELY ON THE ECMWF...YOU WOULD HAVE A NEAR
ADVISORY ALONG THE FOOTHILLS WITH SNOW. RAIN SHOULD CHANGE TO
SNOW QUICKLY THIS EVENING WITH SUCH DRY LOW LEVELS. HAVE DECIDED
TO ISSUE A WINTER WEATHER ADVISORY FOR THE WEST AND FOOTHILLS THIS
EVENING THROUGH WEDNESDAY AFTERNOON. SNOW WILL LINGER INTO THE
MORNING AND TAPER OFF IN THE AFTERNOON NOW WITH A SLOWER MOVEMENT.
ALSO INCLUDED THE BIGHORN MOUNTAINS IN THE ADVISORY AND EXTENDED
IT THERE THROUGH WEDNESDAY EVENING. DECIDED TO LEAVE SOUTHERN BIG
HORN COUNTY...SHERIDAN COUNTY WYOMING AND SOUTHERN ROSEBUD COUNTY
OUT OF THE ADVISORY FOR NOW AS THE START TIME WAS DELAYED AND SNOW
MAY NOT GET IN THERE UNTIL WEDNESDAY MORNING.

RAISED POPS OVER THE EAST FOR WEDNESDAY AS MODELS...AT LEAST THE
GFS...WERE SWEEPING ASCENT INTO EASTERN MONTANA THE LAST FEW RUNS.
THE GFS FORMS AN ELONGATED UPPER TROUGH AND STRETCHES IT NORTH
INTO EASTERN MONTANA FOR CONVERGENCE. THE ECMWF WAS NOT AS
AGGRESSIVE...BUT IT TOO WAS TRENDING IN THIS DIRECTION. MODELS
DROP 850MB TEMPERATURES BELOW 0C OVER THE EAST...SO PRECIPITATION
WOULD LIKELY BE SNOW. DAY TIME STARTING OF THE SNOW COULD LIMIT
THE ACCUMULATION A BIT...SO WILL KEEP SNOW AMOUNTS LIMITED FOR NOW
BUT WILL NEED TO BE WATCHED. HIGHS WEDNESDAY WILL BE MUCH COOLER
WITH READINGS MAX OUT IN THE 40S. NORTHWEST WINDS WILL BE STRONG
TUESDAY NIGHT AND WEDNESDAY AND MAKE IT FEEL EVEN COLDER. THIS
WILL BE A DRAMATIC CHANGE FROM TUESDAY!! TWH

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

MODELS CONTINUED TO SLOW DOWN THE DEPARTURE OF THE MIDWEEK STORM
SYSTEM...LIKELY DUE TO THE UPPER LOW CUTTING OFF TO THE S OF THE
REGION. HAVE ADDED SOME POPS TO THE SE ZONES THU MORNING TO
ACCOUNT FOR THIS SLOWER DEPARTURE. THE REMAINDER OF THU THROUGH
FRI NIGHT CONTINUED TO LOOK DRY WITH A WARMING TREND AS UPPER
RIDGING SLIDES ACROSS THE AREA.

THE REMAINDER OF THE PERIOD WILL BE UNSETTLED. MODELS DROP A
SHORTWAVE THROUGH THE AREA SAT INTO SUN. A COLD FRONT WILL
ACCOMPANY THE WAVE ON SAT. THE GOING POPS LOOKED REASONABLE. WEAKLY
CYCLONIC FLOW FOLLOWS THE WAVE THROUGH MON BEFORE ANOTHER WAVE AND
COLD FRONT DROPS INTO THE AREA MON NIGHT INTO TUE. THE CYCLONIC
FLOW AND ENSUING WAVE WILL BE ON THE W SIDE OF AN UPPER LOW THAT
WILL SET UP OVER THE HUDSON BAY. KEPT POPS ACROSS THE AREA FOR SUN
NIGHT. MON AND MON NIGHT LOOKED A BIT DRIER SO HAD LOWER POPS.
WENT WITH LOW POPS ACROSS THE AREA FOR TUE WITH THE NEXT SYSTEM.

SAT WILL BE WARM AHEAD OF THE COLD FRONT...THEN TEMPERATURES WILL
DROP BACK INTO THE 50S FOR SUN. EXPECT HIGHS IN THE 50S AND 60S MON
AND TUE. ARTHUR

&&

.AVIATION...

VFR CONDITIONS WILL PREVAIL THIS MORNING. A STRONG COLD FRONT
WILL MOVE E THROUGH THE KLVM AREA AROUND 22Z. ISOLATED TO
SCATTERED SHOWERS AND THUNDERSTORMS WILL MOVE INTO THE AREA FROM
KBIL W THIS AFTERNOON. MVFR CONDITIONS WILL ACCOMPANY THE
PRECIPITATION. EXPECT GUSTY S SURFACE WINDS E OF KBIL THIS
AFTERNOON...AND GUSTY WSW WINDS FROM KBIL W. THERE WILL ALSO BE
AREAS OF MOUNTAIN OBSCURATION. THE COLD FRONT WILL CROSS THE AREA
TONIGHT...AND IS EXPECTED TO MOVE THROUGH KBIL AROUND 01Z...AND
KMLS AND KSHR AROUND 04Z. AFTER EARLY EVENING SHOWERS AND
THUNDERSTORMS...PRECIPITATION WILL CHANGE TO A RAIN/SNOW MIX
ACROSS THE AREA. SOME THUNDERSTORMS MAY CONTAIN WIND GUSTS IN
EXCESS OF 50 KT E OF KBIL. SURFACE WINDS WILL GUST FROM THE NW TO
35 TO 45 KT BEHIND THE FRONT. MVFR/IFR CONDITIONS WILL ACCOMPANY
THE PRECIPITATION TONIGHT...WITH LOWER CONDITIONS POSSIBLE DUE TO
THE MIX OF GUSTY WINDS AND RAIN/SNOW. THE MOUNTAINS WILL BE
OBSCURED. ARTHUR

&&

.PRELIMINARY POINT TEMP/POPS...

    TDY WED     THU     FRI     SAT     SUN     MON
-------------------------------------------------------
BIL 076 036/046 031/059 036/064 041/067 039/057 035/060
    2/T 86/W    00/U    00/U    02/W    22/W    22/W
LVM 067 033/045 026/058 034/065 038/064 034/055 032/059
    4/T 95/W    00/U    00/U    02/W    33/W    21/B
HDN 082 037/047 030/060 034/066 037/070 036/059 033/061
    1/N 88/W    20/U    00/U    02/W    32/W    22/W
MLS 086 041/050 032/061 036/067 040/070 037/058 033/059
    0/N 47/W    20/U    00/U    01/B    22/W    22/W
4BQ 085 039/045 030/057 032/065 037/070 036/057 032/058
    0/N 38/W    41/B    00/U    00/U    32/W    22/W
BHK 084 040/049 031/059 033/065 036/069 035/056 031/056
    0/N 26/W    41/B    00/U    01/U    32/W    22/W
SHR 080 036/040 026/054 030/061 035/067 034/054 031/057
    1/N 79/W    41/B    00/U    01/B    33/W    22/W

&&

.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...RED FLAG WARNING IN EFFECT FROM 11 AM THIS MORNING TO 10 PM
      MDT THIS EVENING BELOW 6000 FEET FOR ZONES
      28-34-39>41-56-63>68.
     RED FLAG WARNING IN EFFECT FROM 11 AM THIS MORNING TO 10 PM
      MDT THIS EVENING FOR ZONES 29>33-35>38-42-57-58.
     WINTER WEATHER ADVISORY IN EFFECT FROM 9 PM THIS EVENING TO 6
      PM MDT WEDNESDAY FOR ZONES 40-56-64>66.
WY...RED FLAG WARNING IN EFFECT FROM 11 AM THIS MORNING TO 10 PM
      MDT THIS EVENING FOR ZONES 98-99.
     WINTER WEATHER ADVISORY IN EFFECT FROM MIDNIGHT TONIGHT TO
      MIDNIGHT MDT WEDNESDAY NIGHT FOR ZONE 98.

&&

$$
WEATHER.GOV/BILLINGS



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