Area Forecast Discussion
Issued by NWS Great Falls, MT

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FXUS65 KTFX 291258
AFDTFX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
658 AM MDT SAT AUG 29 2015

.DISCUSSION...
RADAR WAS INDICATING A FEW LIGHT RAIN SHOWERS OVER SW MT EARLY
THIS MORNING WHICH ARE MOVING INTO AREA WHERE THERE IS NO MENTION
OF PRECIPITATION SO HAVE UPDATED TO BETTER REFLECT WHAT IS GOING
ON RELATIVE TO THE RADAR. BLANK

&&

.AVIATION...
UPDATED 1145Z.

SOUTHWESTERLY FLOW ALOFT WILL CONTINUE TO BRING MID AND HIGH LEVEL
CLOUDS TO MONTANA TODAY THROUGH SUNDAY MORNING. SURFACE COLD FRONT
WILL MOVE THROUGH THE FORECAST AREA SATURDAY EVENING BRINGING GUSTY
WESTERLY WINDS WITH ISOLATED TO SCATTERED SHOWERS AND THUNDERSTORMS.
WIDESPREAD WILDFIRE SMOKE WILL CONTINUE TO PRODUCE AREAS IFR/MVFR
VISIBILITIES THROUGH THE FORECAST PERIOD. MPJ

&&

.FIRE WEATHER... A RED FLAG WARNING IS NOW IN EFFECT FOR NOON TO
9 PM MDT SATURDAY FOR FIRE ZONES 112/114/116/117/118. FORECAST IS
STILL ON TRACK FOR LOW HUMIDITY CONDITIONS AND GUSTY WINDS TO
DEVELOP AHEAD OF A PACIFIC COLD FRONT THAT WILL CROSS EAST OF THE
CONTINENTAL DIVIDE BY SATURDAY EVENING. LOOK FOR AFTERNOON HUMIDITY
VALUES TO DROP INTO THE 15 TO 25 PERCENT RANGE WITH WIND GUSTS OF
20 TO 30 MPH AHEAD OF THE FRONT. WINDS WILL REMAIN GUSTY (WITH
GUSTS OF 30-35 MPH) INTO SATURDAY EVENING FOLLOWING FRONTAL
PASSAGE BEFORE GRADUALLY TAPERING OFF AFTER SUNSET.

&&

.PREV DISCUSSION...
/ISSUED 545 AM MDT SAT AUG 29 2015/

SATURDAY TO MONDAY...FIRE WEATHER CONCERNS WILL CONTINUE TO REMAIN
HEIGHTENED AS RED FLAG WARNING REMAINS IN PLACE THIS AFTERNOON AND
EVENING FOR MUCH OF THE AREA. A COLD FRONT WILL MOVE ACROSS THE
REGION SATURDAY AND SUNDAY. WINDS AHEAD OF THE COLD FRONT ARE
EXPECTED TO BE STRONG AND GUSTY AND SHOULD INCREASE IN SPEED
AROUND THE SAME TIME AS DAYTIME MAXIMUM TEMPERATURES ARE REACHED.
MODELS ARE SLOWLY ADDING MORE MOISTURE TO THE COLD FRONTAL
PASSAGE...HOWEVER PRECIPITATION AMOUNTS STILL LOOK TO BE
RELATIVELY LIGHT AND WIDESPREAD. THE FRONT SHOULD MOVE ACROSS THE
AREA BY SUNDAY MORNING AND COOLER TEMPERATURES ARE EXPECTED FOR
THE REMAINDER OF THE PERIOD. SOME BRIEF INCREASE IN VISIBILITY
DUE TO LESS SMOKE IS POSSIBLE SATURDAY AND SUNDAY HOWEVER
CONFIDENCE IN HOW LONG AN INCREASE IN VISIBILITY WILL LAST IS
RATHER LOW. THERE IS A CHANCE OF ADDITIONAL SHOWERS SUNDAY
AFTERNOON HOWEVER ANY PRECIPITATION WILL AGAIN BE RELATIVELY LIGHT
AND WIDELY SCATTERED. CONDITIONS MONDAY ARE EXPECTED TO DRY OUT
AGAIN...WITH TEMPERATURES REMAINING NEAR OR SLIGHTLY BELOW
SEASONAL VALUES. SMOKE IS EXPECTED TO BE LIMITING VISIBILITIES BY
MONDAY. SUK

MONDAY NIGHT THROUGH SATURDAY...MODELS CONTINUE TO SHOW THAT THE
MAIN INFLUENCE ON MONTANA WEATHER DURING THE MEDIUM RANGE PERIOD
WILL BE AN UPPER LEVEL TROUGH THAT STARTS OFF THE PERIOD OVER
CANADA`S WEST COAST. DIFFERENCE TONIGHT IS THAT BOTH THE ECMWF AND
THE GFS HAVE EVOLVED THEIR SOLUTIONS OVER THE LAST 24 HOURS TO
SUGGEST THAT THIS FEATURE WILL DEEPEN OVER THE PACIFIC NORTHWEST AND
PROGRESS INLAND AS FAR AS THE NORTHERN ROCKIES. AS A RESULT, BOTH
MODELS ARE NOW TRENDING TO A COOLER AND SOMEWHAT WETTER SOLUTION FOR
WEDNESDAY NIGHT THROUGH SATURDAY. THIS NEW SOLUTION DEVELOPED WITH
THE FRIDAY 12Z MODEL RUN AND CONTINUES TO APPEAR TONIGHT. WHILE
CONFIDENCE IN THIS EVOLUTION IS NOT ABSOLUTE, IT IS ENCOURAGING THAT
BOTH MODELS HAVE TRENDED THIS WAY. CURRENT FORECAST PACKAGE KEEPS
TUESDAY/WEDNESDAY TIME FRAME SIMILAR TO WHAT HAS BEEN FORECAST FOR
SEVERAL DAYS NOW. FOR THURSDAY AND BEYOND, I HAVE TAKEN THE FIRST
STEPS TO BEGIN INCREASING POPS AND COOLING TEMPERATURES TOWARD THIS
NEW SOLUTION. HAVE ALSO OPTED TO REMOVE MENTION OF SMOKE FOR
THURSDAY AND BEYOND. WHILE THIS MODEL TREND STILL DOES NOT INDICATE
A SEASON-ENDING EVENT FOR WESTERN WILDFIRES, IT WOULD APPEAR THAT
SOME RAIN AND A MORE NORTHERLY WIND DIRECTION SHOULD REDUCE SMOKE
COVERAGE. MPJ

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  92  60  78  50 /  20  20  20  10
CTB  88  53  71  47 /  10  20  10  10
HLN  89  56  79  44 /  30  30  20  10
BZN  89  55  82  42 /  20  20  30  10
WEY  81  45  71  30 /  20  30  20  10
DLN  86  55  76  41 /  20  30  20  10
HVR  94  60  81  49 /  20  40  30  20
LWT  92  58  81  44 /  10  20  50  30

&&

.TFX WATCHES/WARNINGS/ADVISORIES...
RED FLAG WARNING FROM NOON TODAY TO 9 PM MDT THIS EVENING FOR
MTZ112-114-116>118.

&&

$$

WEATHER.GOV/GREATFALLS



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