Area Forecast Discussion
Issued by NWS Billings, MT

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000
FXUS65 KBYZ 051554
AFDBYZ

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE BILLINGS MT
954 AM MDT TUE MAY 5 2015

.UPDATE...

MINOR ADJUSTMENTS TO THE GOING FORECAST TODAY. AREA WILL BE UNDER
A SOUTHERLY FLOW REGIME TODAY AHEAD OF TONIGHTS COLD FRONT. A
COUPLE OF DISTURBANCES CROSSING SOUTH TO NORTH OVER WESTERN ZONES
THIS AFTERNOON WILL TRIGGER ISOLATED TO SCATTERED THUNDERSTORMS.
SHEAR PROFILES AND INSTABILITY LOOK WEAK SO NOT EXPECTING ANY
SEVERE STORMS BUT COULD SEE AN ISOLATED STRONG WIND GUST WITH THIS
ACTIVITY. LOOKS LIKE THIS MORNING WILL BE MAINLY DRY SO DROPPED
MOST POPS BEFORE NOON. ALSO REMOVED MENTION OF AFTERNOON POPS FOR
SOUTHEAST MONTANA AS IT LOOKS CONVECTION WILL HOLD OFF UNTIL LATER
IN THE EVENING THERE. LOWERED RH/TD VALUES A BIT AS WELL AHEAD OF
THE FRONT. REST OF THE FORECAST IN PRETTY GOOD SHAPE. CHAMBERS

&&

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

UNSETTLED WEATHER BEGINS TODAY AND WILL CONTINUE RIGHT THROUGH
THE REMAINDER OF THE WEEK. AN UPPER LOW AND TROUGH WILL MOVE ONTO
THE PACIFIC NORTHWEST COAST TODAY AND REMAIN STATIONARY OR SLOWLY
SHIFT SOUTHEAST TOWARD THE GREAT BASIN AREA DURING THE DAY
WEDNESDAY. THIS WILL ALLOW A SOUTHWEST FLOW ALOFT TO BEGIN TO
DEVELOP OVER OUR AREA TODAY AND ESPECIALLY BE IN PLACE FOR
WEDNESDAY. SEVERAL SURFACE LOWS WILL DEVELOP ACROSS THE NORTHERN
AND CENTRAL ROCKIES BRINGING A PREDOMINATELY SOUTHEAST SURFACE
FLOW ALLOWING FOR INCREASING LOW-LEVEL MOISTURE ACROSS THE AREA
THROUGH WEDNESDAY. MODELS INCLUDING THE HRRR BRING A VORT MAX OVER
OUR AREA TODAY RESULTING IN SHOWERS AND ISOLATED THUNDERSTORMS.
SHEAR IS A BIT BETTER TODAY BUT STILL NOT IMPRESSIVE. CAPES ARE
ALSO SLIGHTLY BETTER TODAY AND MORE WIDESPREAD SO THUNDERSTORM
CHANCES WILL BE BETTER TODAY THAN TUESDAY. PRE-FRONTAL WARMING
TODAY WILL ALLOW TEMPERATURES TO WARM WELL INTO THE 70S TO AROUND
80 DEGREES

A COLD FRONT WILL MOVE ACROSS THE FORECAST AREA WEDNESDAY MORNING
USHERING IN GUSTY NORTHWEST WINDS BY AFTERNOON ALONG WITH A CHANCE
FOR SHOWERS AND ISOLATED THUNDERSTORMS. TEMPERATURES WILL BE MUCH
COOLER WITH READINGS ONLY IN THE LOWER TO MIDDLE 60S SO
INSTABILITY FOR THUNDERSTORMS WILL NOT BE AS GOOD AS TODAY. A
STRONGER DISTURBANCE AND UPPER LOW WILL MOVE NORTHEAST OUT OF
WYOMING WEDNESDAY INTO WEDNESDAY NIGHT. MODELS SHOW GOOD WRAP-
AROUND MOISTURE WITH THIS ALONG WITH DECENT QPF AMOUNTS. AS A
RESULT...HAVE INCREASED POPS INTO THE LIKELY AND CATEGORICAL RANGE
DURING THIS TIME FROM CUSTER AND POWDER RIVER COUNTIES EASTWARD.
ELSEWHERE...EXPECT SCATTERED SHOWERS AND THUNDERSTORMS. HOOLEY

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


LATEST MODEL RUNS HAVE CONTINUED TO KEEP THE BULK OF THE ENERGY
AND MOISTURE OUT OF THE THE AREA. MODELS HAVE CONTINUED TO TRACK
WELL WITH EACH OTHER...WITH THE 00Z DATA HAVING MORE OF A CLOSED
LOW EJECTING FROM THE GREAT BASIN THIS WEEKEND...BUT IT TRACKS
MORE INTO THE CENTRAL PLAINS. THIS HAS THE EFFECT OF KEEPING THE
BULK OF THE MOISTURE AND ENERGY SOUTH OF MONTANA. CONTINUE TO SEE
DIFFLUENT FLOW ALOFT ACROSS THE AREA THIS WEEKEND...ALONG WITH
SOME MID-LEVEL MOISTURE. THIS WILL KEEP AT LEAST A CHANCE OF LIGHT
SCATTERED PRECIP ACROSS THE AREA. HAVE TRENDED POPS DOWN SOME
GIVEN THE TREND AWAY FROM A MORE FAVORABLE SOLUTION. THE COLUMN
IS NOT OVERLY SATURATED...WITH PRECIPITABLE WATER VALUES ONLY
AROUND A HALF INCH. THE POTENTIAL FOR MUCH ACCUMULATION REMAINS
LOW. WITH THE MID LEVEL MOISTURE...MUCH OF THE EXTENDED PERIOD
WILL BE CLOUDY...THUS COOLER. TEMPERATURES CONTINUE BE IN THE 50S
FOR HIGHS. REIMER

&&

.AVIATION...

VFR CONDITIONS WILL PREVAIL THIS MORNING. ISOLATED TO SCATTERED
SHOWERS AND THUNDERSTORMS WILL DEVELOP FROM ROUNDUP TO KBIL TO
KSHR W THIS AFTERNOON...AND CONTINUE INTO EARLY EVENING. THE
PRECIPITATION WILL PRODUCE MVFR/IFR CONDITIONS. AREAS OF MOUNTAIN
OBSCURATION WILL DEVELOP THIS AFTERNOON. PRECIPITATION WILL BECOME
MORE WIDESPREAD THIS EVENING AS A COLD FRONT PUSHES INTO THE AREA
BRINGING A WIND SHIFT TO THE NW AT KLVM BY 06Z. THE THREAT FOR
THUNDER WILL DECREASE LATE THIS EVENING. SCATTERED SHOWERS ARE
EXPECTED LATE TONIGHT. MVFR TO IFR CONDITIONS WILL CONTINUE WITH
THE PRECIPITATION TONIGHT...WITH AREAS OF MOUNTAIN OBSCURATION.
THE COLD FRONT WILL REACH KMLS BY 12Z WED. ARTHUR

&&

.PRELIMINARY POINT TEMP/POPS...

    TDY WED     THU     FRI     SAT     SUN     MON
-------------------------------------------------------
BIL 079 049/059 040/053 040/053 039/051 038/059 040/060
    2/T 43/W    22/W    24/W    55/W    43/W    32/W
LVM 076 043/061 036/050 034/048 034/050 034/059 035/060
    3/T 64/W    35/W    35/W    55/W    43/W    33/W
HDN 082 050/061 042/056 038/057 039/053 037/059 035/062
    1/B 34/W    22/W    23/W    55/W    43/W    32/W
MLS 079 051/060 041/055 037/056 038/054 037/057 038/061
    1/B 38/W    42/W    12/W    44/W    43/W    32/W
4BQ 075 051/061 043/055 035/055 039/052 035/053 034/059
    1/B 48/T    42/W    12/W    55/W    44/W    32/W
BHK 073 050/060 042/054 034/054 035/052 034/054 031/057
    1/N 39/T    72/W    12/W    44/W    33/W    22/W
SHR 075 048/054 037/053 035/054 038/050 035/051 032/058
    2/T 45/W    43/W    34/W    55/W    54/W    33/W

&&

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

&&

$$
WEATHER.GOV/BILLINGS


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