Area Forecast Discussion
Issued by NWS Billings, MT

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000
FXUS65 KBYZ 260917
AFDBYZ

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BILLINGS MT
317 AM MDT WED AUG 26 2015

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

UPPER RIDGE REMAINS IN PLACE OVER THE AREA TODAY RESULTING IN
TEMPERATURES OVER 90 DEGREES AGAIN. THERE WILL BE MORE CLOUD
COVER TODAY AS MONSOONAL MOISTURE FETCH MOVES INTO THE AREA FROM
THE SOUTH. ENERGY ASSOCIATED WITH THIS MOISTURE ALONG WITH STEEP
MID LEVEL LAPSE RATES WILL BRING A BETTER CHANCE FOR ISOLATED TO
SCATTERED THUNDERSTORMS THIS AFTERNOON AND EVENING...MAINLY SOUTH
OF A LIVINGSTON TO BILLINGS TO EKALAKA LINE. CAN`T RULE OUT A
STRONG STORM OVER FAR SOUTHEAST MONTANA THIS EVENING IN AREA WHERE
BETTER LOW LEVEL MOISTURE EXISTS...BUT 700MB TEMPS OF 12-15C IN
THIS AREA WILL MOST LIKELY LIMIT CONVECTIVE STRENGTH RESULTING IN
GENERAL HIGH BASED STORM DEVELOPMENT.

UPPER LOW OFF THE NORTHWEST COAST WILL PUSH SOME ENERGY ONSHORE ON
THURSDAY WHICH WILL LOWER HEIGHTS ALOFT AND BRING A BIT COOLER
TEMPERATURES TO THE AREA. EXPECT HIGHS IN THE 80S TO LOWER 90S. A
WEAK WEST TO EAST RIPPLE IN THE MID LEVELS COMBINED WITH
PRECIPITABLE WATER VALUES OVER 3/4 OF AN INCH ON THURSDAY
AFTERNOON WILL PROVIDE IMPETUS FOR SCATTERED THUNDERSTORM
DEVELOPMENT. THESE STORMS WILL SHIFT EAST ACROSS THE FORECAST
AREA THURSDAY NIGHT. NOT EXPECTING MUCH IN THE WAY OF
PRECIPITATION ACCUMULATION WITH THESE STORMS BUT MORE LOCATIONS
WILL HAVE A CHANCE FOR SOMETHING MEASURABLE.

SMOKE SHOULD BE A BIT LESS NOTICEABLE TODAY WITH WIND DIRECTION
SHIFTING MORE SOUTHERLY TODAY. WINDS TURN BACK TO THE WEST WITH
THURSDAYS UPPER WAVE WHICH WILL LIKELY BRING MORE SMOKE INTO THE
REGION. CHAMBERS


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

THE GFS AND ECMWF SHOWED GOOD AGREEMENT THROUGH SUN
MORNING...LENDING HIGHER CONFIDENCE TO THE FORECAST. THE GFS
ENSEMBLES HAD LOW SPREAD UNTIL MON AND TUE...AND THE ECMWF
ENSEMBLES WERE TRENDING TOWARD BETTER PATTERN AGREEMENT. MADE JUST
A FEW POP ADJUSTMENTS TO THE GOING FORECAST.

SW FLOW WILL GRADUALLY OVERTAKE THE REGION ON SAT AS UPPER RIDGING
SHIFTS OFF TO THE E. CONTINUED THE LOW MOUNTAIN POPS THROUGH SAT
MORNING...AND KEPT THE LOW POPS OVER THE WESTERN AND CENTRAL ZONES
SAT AFTERNOON AND EVENING AS A COLD FRONT PUSHED E INTO THE AREA.
IT WILL BE HOT AND DRY AHEAD OF THE FRONT ON SAT...BUT WINDS WILL
NOT BE OVERLY STRONG SO NOT TOO CONCERNED ABOUT FIRE WEATHER AT
THIS TIME. THE AREA WILL BE POST-FRONTAL SUN MORNING WITH LOW
CHANCES FOR THUNDERSTORMS CENTRAL AND W. NOTED THE GFS HAD BEEN
SHOWING A TAP INTO SUBTROPICAL MOISTURE FOR SAT THROUGH SUN WHICH
WILL SUPPORT HEAVY RAINFALL WITH THUNDERSTORMS.

ON SUN AFTERNOON...THE GFS MAINTAINS SW FLOW OVER THE AREA...WHILE
THE ECMWF FLATTENS OUT THE FLOW AND BRINGS A SHORTWAVE E ALONG THE
CANADIAN/MT BORDER. WENT WITH CLIMO POPS THROUGH SUN EVENING DUE
TO THIS DIFFERENCE. BOTH MODELS HAD A TROUGH APPROACHING THE AREA
ON MON BUT THE TROUGH WAS MUCH STRONGER ON THE GFS THAN THE ECMWF.
AGAIN WENT WITH CLIMO POPS THROUGH MON EVENING. A FLATTER DRIER
FLOW WAS IN STORE FOR TUE. SW FLOW RETURNED FOR WED BUT THE
AIRMASS LOOKED DRY...SO JUST HAD MOUNTAIN POPS.

SAT WILL BE THE HOTTEST DAY OF THE PERIOD AHEAD OF THE COLD FRONT.
HIGHS WILL BE IN THE 80S THE REST OF THE PERIOD WITH COOLER
WEATHER POSSIBLE TUE AND WED. ARTHUR
&&

.AVIATION...

THERE WILL BE A SLIGHT CHANCE OF THUNDERSTORMS ALONG AND S OF A
LINE FROM AROUND KLVM TO LODGE GRASS TO FAR SE MT AFTER 18Z
TODAY...INCLUDING AROUND KSHR. LOCALIZED MVFR CONDITIONS ARE
POSSIBLE WITH THE THUNDERSTORMS...WITH AREAS OF MOUNTAIN
OBSCURATION. THE SLIGHT CHANCE OF THUNDERSTORMS WILL SPREAD NE
THIS EVENING TO INCLUDE KBIL. CHANCES FOR THUNDERSTORMS WILL BE
CONFINED TO S OF HARDIN...E AND S OF KMLS AND OVER AND NEAR THE
BEARTOOTH/ABSAROKA MOUNTAINS AFTER 06Z TONIGHT. MVFR TO IFR
CONDITIONS ARE POSSIBLE IN THE PRECIPITATION OVERNIGHT. EXPECT
LOCALIZED TO AREAS OF MOUNTAIN OBSCURATION TONIGHT. ARTHUR
&&

.PRELIMINARY POINT TEMP/POPS...

    TDY THU     FRI     SAT     SUN     MON     TUE
-------------------------------------------------------
BIL 093 063/089 060/089 062/094 059/083 057/083 053/081
    1/B 22/T    31/B    12/T    22/T    22/T    21/U
LVM 091 056/088 052/087 055/090 050/080 050/080 045/078
    2/T 23/T    32/T    12/T    22/T    22/T    21/B
HDN 096 061/093 057/091 059/097 057/087 057/086 052/084
    1/B 22/T    31/B    12/T    22/T    22/T    21/U
MLS 097 065/094 061/093 062/098 061/088 060/087 055/085
    1/B 12/T    21/B    11/B    12/T    22/T    21/U
4BQ 094 061/088 058/091 059/097 058/087 058/087 055/084
    1/B 33/T    21/B    11/U    12/T    22/T    21/U
BHK 093 060/089 057/091 059/096 058/088 057/087 054/082
    1/B 23/T    11/B    11/U    12/T    22/T    21/U
SHR 094 056/088 052/089 053/094 053/086 053/086 050/083
    2/T 22/T    31/B    11/B    12/T    22/T    21/U

&&

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

&&

$$
WEATHER.GOV/BILLINGS



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