Area Forecast Discussion
Issued by NWS Billings, MT

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000
FXUS65 KBYZ 301455
AFDBYZ

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE BILLINGS MT
855 AM MDT SUN AUG 30 2015

.UPDATE...

GIVEN EXTENSIVE CLOUD COVER THIS MORNING...WE DROPPED HIGHS 1 TO 3
F IN SEVERAL LOCATIONS TODAY USING A 06 UTC MULTI-MODEL CONSENSUS.
THIS IN SPITE OF THE VERY WARM START TO THE DAY. OTHERWISE...ONLY
MINOR CHANGES WERE MADE TO POPS BASED ON RADAR TRENDS...MAINLY TO
PUSH A SLIGHT CHANCE FURTHER EASTWARD INTO SOUTHEASTERN MT BEFORE
NOON. WE ARE LEAVING THE RED FLAG WARNING IN PLACE ACROSS SOUTH
CENTRAL MT AS A DRYING TREND WITH INCREASING SOUTHWEST WINDS WILL
TAKE PLACE DURING THE LATE AFTERNOON. A COLD FRONTAL PASSAGE IS
ALSO STILL ON TRACK FOR THIS EVENING...BUT THE 12 UTC NAM AND 06
UTC GFS SUGGEST IT COULD BE A BIT SLOWER TO ARRIVE THAN EARLIER
THOUGHT. SCHULTZ

&&

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

AN UPPER LOW AND TROUGH CURRENTLY MOVING ACROSS THE PACIFIC
NORTHWEST WILL MOVE ACROSS OUR FORECAST AREA TODAY AND TONIGHT.
AREAS OF VORTICITY HAVE ALREADY MOVED INTO THE WESTERN HALF OF THE
STATE THIS MORNING AND THIS HAS BEEN PRODUCING SCATTERED SHOWERS
AND ISOLATED THUNDERSTORMS ACROSS WESTERN MONTANA SOUTHWARD INTO
WESTERN WYOMING. SOME OF THIS ACTIVITY HAS MADE IT INTO OUR
CENTRAL AND WESTERN ZONES BUT THE BULK OF THE ACTIVITY HAS BEEN
OVER THE MOUNTAINS. AS THE SYSTEM MOVES EAST TODAY IT WILL BRING A
CONTINUED CHANCE FOR SHOWERS AND THUNDERSTORMS ACROSS OUR FORECAST
AREA WITH THE HIGHEST CHANCES ALONG AND WEST OF A ROUNDUP-
BILLINGS- SHERIDAN LINE.

THE MAIN WEATHER IMPACT FOR THE SHORT TERM PERIOD WITH BE A
STRONG PACIFIC FRONT THAT WILL SWEEP ACROSS OUR WESTERN COUNTIES
LATE THIS AFTERNOON INTO THIS EVENING AND OUR FAR EASTERN COUNTIES
LATE TONIGHT. SOUTHWEST WINDS WILL GUST IN THE 30 TO 40 MPH RANGE
AHEAD OF THE FRONT ACROSS OUR CENTRAL AND WESTERN AREAS. WINDS
WILL SHIFT TO THE WEST AND NORTHWEST BEHIND THE FRONT AND CONTINUE
TO BE QUITE GUSTY AT TIMES THIS EVENING AND OVERNIGHT.
TEMPERATURES TODAY WILL BE SLIGHTLY COOLER THAN YESTERDAY BUT
STILL VERY WARM WITH 80S TO LOWER 90S COMMON. ALTHOUGH HUMIDITIES
WILL BE HIGHER...THE COMBINATION OF DRY CONDITIONS...VERY WARM
TEMPERATURES AND A STRONG FRONT WILL RESULT IN DANGEROUS FIRE
CONDITIONS THIS AFTERNOON INTO EARLY THIS EVENING.

A DRY ZONAL FLOW ALOFT WILL PREVAIL FOR MONDAY. TEMPERATURES WILL
COOL TO MORE NORMAL LEVELS FOR THIS TIME OF YEAR WITH UPPER 70S TO
LOWER 80S COMMON. HOOLEY

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

OVERALL EXTENDED PERIOD IS PROGRESSIVE AS THE STRONGEST JET ENERGY
AROUND THE PACIFIC NORTHWEST TROUGH REACHES THE BASE OF THE TROUGH
TUESDAY NIGHT AND THE LAST OF THE IMPULSES MAINTAINING THE STRONG
FLOW ALOFT EXITS THE AREA LATER ON SATURDAY. THERE IS A SUBTLE
PATTERN CHANGE WEDNESDAY INTO THURSDAY WHERE MODELS INDICATE A BIT
BETTER INFUSION OF SUBTROPICAL MOISTURE INTO THE SOUTHWEST FLOW
ALOFT WHICH INCREASES THE CHANCE OF SHOWER AND THUNDERSTORM
ACTIVITY BY THURSDAY.THE EJECTING PACIFIC NORTHWEST TROUGH AXIS
WEAKENS OVER THE WEEKEND BUT GIVES A CHANCE FOR UNSETTLED WEATHER
BEFORE DRYING BEGINS TO KICK IN ON SUNDAY.

TEMPERATURES COOL LATE IN THE WEEK AS THE THE APPROACH OF THE
TROUGH BRINGING LOWERING HEIGHTS AND PUSHING THE SURFACE TROUGH
INTO THE DAKOTAS. FRIDAY AND SATURDAY COULD BE NEAR 70 WITH SOME
LOCATIONS REMAINING IN THE 60S. BORSUM

&&

.AVIATION...

ISOLATED SHOWERS AND THUNDERSTORMS CAN BE EXPECTED THIS MORNING
ACROSS THE ENTIRE AREA. THE STRONGER ACTIVITY WILL BE FROM
BILLINGS WESTWARD...WHERE A WIND GUST TO 40KTS IS POSSIBLE. THE
ACTIVITY SHOULD DRIFT INTO NORTHERN MONTANA THIS AFTERNOON. WINDS
WILL INCREASE FROM BILLINGS WEST THIS AFTERNOON WITH SOME GUSTS TO
35KTS EXPECTED AT LIVINGSTON. A COLD FRONT WILL RUSH THROUGH THE
AREA LATE THIS AFTERNOON AND EVENING...SWITCHING WINDS TO THE
NORTHWEST WITH SOME GUSTS TO 35KTS WITH THE FRONT. ALSO...WIDELY
SCATTERED SHOWERS AND THUNDERSTORMS WILL DEVELOP ALONG AND BEHIND
THE FRONT. THE STORMS WILL CONTAIN STRONG WIND GUSTS. TWH

&&

.PRELIMINARY POINT TEMP/POPS...

    TDY MON     TUE     WED     THU     FRI     SAT
-------------------------------------------------------
BIL 086 054/082 055/088 059/088 055/074 048/069 047/070
    3/T 20/U    00/U    11/U    11/B    23/T    33/T
LVM 085 046/081 046/085 050/084 046/072 041/066 038/069
    3/T 20/K    00/K    11/B    23/T    44/T    43/T
HDN 089 052/082 053/091 057/092 054/078 048/073 048/072
    2/T 20/U    01/U    11/U    11/B    22/T    33/T
MLS 088 057/082 054/091 060/094 058/081 051/074 049/073
    2/T 30/U    00/U    11/U    11/B    22/T    22/T
4BQ 091 056/080 055/091 059/094 058/082 053/076 051/071
    2/T 30/U    00/U    11/U    11/U    13/T    33/T
BHK 092 053/079 052/090 057/094 057/084 051/076 049/073
    2/T 30/U    01/U    10/U    11/U    12/T    33/T
SHR 089 050/083 047/090 054/091 051/081 046/073 044/070
    2/T 20/U    00/U    11/U    11/B    12/T    33/T

&&

.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...RED FLAG WARNING IN EFFECT UNTIL MIDNIGHT MDT TONIGHT FOR
      ZONES 28-29-34-35-39>42-56-63>68.
WY...NONE.

&&

$$
WEATHER.GOV/BILLINGS



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