Area Forecast Discussion
Issued by NWS Billings, MT

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FXUS65 KBYZ 132110
AFDBYZ

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BILLINGS MT
310 PM MDT SUN APR 13 2014

.SHORT TERM...VALID FOR MON AND TUE...

STORM SYSTEM THAT BROUGHT HEAVY SNOW TO THE MOUNTAINS AND
FOOTHILLS CONTINUES TO MOVE AWAY FROM THE AREA WITH SUN NOW
BREAKING THROUGH OVER SOUTHERN ZONES. BACKSIDE VORTICITY COMBINED
WITH RESIDUAL INSTABILITY WILL KEEP A FEW LIGHT SNOW SHOWERS
AROUND THROUGH EARLY EVENING...BUT NO ACCUMULATIONS EXPECTED. AS
THE SUN SETS THE LOW LEVEL CLOUD COVER WILL DISSIPATE LEAVING
CANADIAN HIGH PRESSURE AND FRESH SNOW COVER TO DROP TEMPERATURES
QUICKLY INTO THE 20S. GUIDANCE SUGGESTING TEMPERATURES IN THE
TEENS TO LOW 20S WITH A FEW SINGLE DIGITS NOT OUT OF THE QUESTION
IN AREAS THAT SAW HEAVY SNOWFALL. THE RECORD LOW FOR MONDAY
MORNING IN SHERIDAN IS 12...AND IS REACHABLE IF STRATUS AND FOG
FAILS TO DEVELOP TONIGHT. MODELS SEEM TO HAVE BACKED OFF OF THE
STRATUS/FOG POTENTIAL FOR TONIGHT...BUT WITH THE AMOUNT OF
MOISTURE THAT FELL AND THE CLEARING SKIES LEFT MENTION IN THE
FORECAST FOR FOOTHILLS LOCATIONS.

AMPLIFIED RIDGE TO THE WEST OF THE AREA SHIFTS EASTWARD ON MONDAY
WITH NORTHWEST FLOW OVER THE AREA. THIS FLOW WILL KEEP
TEMPERATURES FROM JUMPING INTO THE 60S UNTIL TUESDAY WHEN RIDGE
AXIS MOVES OVER THE AREA...FLATTENING AS IT DOES SO. DRY
CONDITIONS WILL PREVAIL MONDAY INTO TUESDAY. LEE SIDE TROFING
WILL INCREASE MONDAY AFTERNOON WHICH WILL INCREASE WINDS IN GAP
FAVORED AREAS FROM LIVINGSTON TO NYE INTO MONDAY EVENING. SPEEDS
LOOK UNDER ADVISORY LEVELS AT THIS TIME BUT WILL KEEP AN EYE ON
THIS POTENTIAL OVER THE NEXT 36 HOURS FOR ANY TRENDS STRONGER.

FIRST PART OF A COMPLEX STORM SYSTEM MOVES INTO THE AREA ON
TUESDAY. MODELS ARE STILL SHOWING A GOOD BIT OF DISAGREEMENT WITH
HOW THIS SYSTEM WILL PLAY OUT FROM TUESDAY AFTERNOON THROUGH
FRIDAY. BASED ON RECENT TRENDS AND CONSISTENCY WOULD LEAN TOWARD
A BLEND OF THE CANADIAN AND GFS WITH THIS SYSTEM AS THE ECMWF HAS
NOT FARED WELL WITH THE PAST COUPLE OF SYSTEMS...BUT THAT DOESN`T
MEAN THE ECMWF ISN`T GOING TO BE CORRECT THIS TIME. AS A RESULT
HAVE GONE WITH BROAD BRUSHED POPS SPREADING FROM WEST TO EAST
TUESDAY AFTERNOON THROUGH TUESDAY NIGHT AS QG FORCING OVER RUNS
AREA OF 700MB FRONTOGENESIS OVER THE AREA. WHILE MID LEVEL
TEMPERATURES COOL FAIRLY QUICKLY DURING THIS PERIOD...THERE IS
LITTLE IN THE WAY OF COLD AIR UNTIL STRONGER PUSH OF CANADIAN AIR
MOVES IN FROM THE NORTHEAST EARLY WEDNESDAY. WITH THESE WARMER
TEMPERATURES HAVE SOME MODEST SNOW ACCUMULATION IN THE MOUNTAINS
AND HIGHER FOOTHILLS BUT FOR THE REST OF THE AREA A RAIN OR
RAIN/SNOW MIX SEEMS REASONABLE. KEPT POPS IN THE CHANCE CATEGORY
FOR MOST AREAS BASED ON THE MODEL INCONSISTENCIES TUESDAY NIGHT.
CHAMBERS


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

MODELS CONTINUE TO TREND TOWARDS CARVING OUT ANOTHER DEEP UPPER
LEVEL TROUGH OVER THE REGION WED INTO EARLY THURS...BUT THERE ARE
STILL LARGE DIFFERENCES IN WHERE THEY TRACK AN UPPER LEVEL LOW
WITHIN THE TROUGH. STILL...HAVE ENOUGH CONFIDENCE TO INCREASE
PRECIP CHANCES WED INTO EARLY THURS...ESPECIALLY ACROSS WESTERN
AND SOUTHERN AREAS. BOTH 700 MB AND 850 MB TEMPS WILL BE COLD
ENOUGH FOR SNOW...AND UPSLOPE FLOW LOOKS SUFFICIENTLY DEEP AT
THIS POINT...SO SOME SNOW ACCUMULATION LOOKS FAIRLY LIKELY ACROSS
THE WESTERN MOUNTAINS AND FOOTHILLS. HIGHS IN THE MID 30S TO NEAR
40 WILL BE COMMON ON WED. THURS...PRECIP SHOULD END BY LATE IN THE
DAY AS THE TROUGH BEGINS TO MOVE EAST. IT WILL REMAIN COOL WITH
HIGHS IN THE 40S TO AROUND 50.

MAJOR DIFFERENCES IN MODEL FORECASTS APPEAR FRI INTO SAT. THE
ECMWF PUSHES A STRONG COLD FRONT THROUGH THE REGION LATE
FRI...KEEPING UPPER LEVEL TROUGHING OVER THE REGION SAT. MEANWHILE
THE GFS AND CANADIAN BUILD IN A BROAD UPPER LEVEL RIDGE THROUGH
SAT WITH JUST A WEAK SURGE OF COOL AIR FRI AHEAD OF A WEAK
SHORTWAVE. DUE TO THE LARGE MODEL DIFFERENCES...I OPTED TO KEEP
THE FRI/SAT FORECAST PRETTY MUCH AS I INHERITED IT. STC

&&

.AVIATION...

VFR WILL PREVAIL ACROSS MOST OF THE REGION THROUGH MON
AFTERNOON...THOUGH BRIEF PERIODS OF MVFR IN SNOW SHOWERS ARE
POSSIBLE THROUGH EARLY THIS EVENING SOUTH AND WEST OF KBIL. AREAS
OF MOUNTAIN OBSCURATION ARE STILL POSSIBLE INTO THE EVENING OVER
THE BEARTOOTH AND BIG HORN MOUNTAINS. GUSTY N TO NW WINDS ACROSS
CENTRAL AND EASTERN ROUTES WILL WEAKEN BY THIS EVENING. STC

&&

.PRELIMINARY POINT TEMP/POPS...

    MON     TUE     WED     THU     FRI     SAT     SUN
-----------------------------------------------------------
BIL 022/052 034/057 033/038 027/049 033/062 037/064 038/065
    10/B    03/W    56/W    32/W    02/W    20/B    01/B
LVM 018/052 033/054 031/037 026/051 031/058 033/062 035/062
    10/N    03/W    66/J    42/W    12/W    20/B    02/W
HDN 021/052 031/060 032/039 025/050 030/065 034/065 035/066
    10/B    02/W    55/W    32/W    02/W    20/B    01/B
MLS 021/050 031/060 029/038 023/047 027/061 034/063 036/065
    00/B    02/W    44/W    12/W    11/B    20/N    01/B
4BQ 021/048 029/060 031/040 023/047 027/064 033/063 035/064
    10/B    01/B    55/W    22/W    11/B    20/B    01/B
BHK 018/043 026/055 025/034 019/041 023/056 031/060 032/062
    00/U    01/B    43/J    11/B    11/B    20/B    01/U
SHR 011/047 027/057 031/038 024/047 027/062 032/063 035/062
    20/U    02/W    65/J    32/W    02/W    20/B    00/B

&&

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

&&

$$
WEATHER.GOV/BILLINGS



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