Area Forecast Discussion
Issued by NWS Great Falls, MT

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FXUS65 KTFX 291757
AFDTFX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
1155 AM MDT SAT AUG 29 2015

.DISCUSSION...

FOR THIS AFTERNOON...LOWERED HIGH TEMPS SOME ACROSS NW SECTIONS
OF CENTRAL MT WHERE THICKER/LOWER CLOUDS APPEAR TO BE
KEEPING TEMPERATURES FROM RISING AS QUICKLY. ELSEWHERE...TEMPS
LOOK GOOD WITH A FEW LOCATIONS NEARING RECORD HIGHS. STILL
EXPECTING ISOLATED TO WIDELY SCATTERED SHOWERS TO DEVELOP THIS
AFTERNOON AND EVENING. INSTABILITY DOESN`T LOOK OVERLY IMPRESSIVE
THIS AFTERNOON...BUT OPTED TO KEEP A MENTION OF THUNDERSTORMS IN
FOR NOW WITH AFTERNOON HEATING/DESTABILIZATION ALLOWING A FEW
POCKETS OF GREATER INSTABILITY TO DEVELOP. MARTIN

&&

.AVIATION...
UPDATED 1755Z.

EXPECT WIDESPREAD MVFR VISIBILITIES IN SMOKE WITH IFR
VISIBILITIES/MVFR CEILINGS CLOSE TO WILDFIRES. A COLD FRONT WILL
SWEEP THROUGH THE AREA LATE THIS AFTERNOON AND COULD BRING SOME
IMPROVEMENT IN VISIBILITIES BUT CONFIDENCE IN WHAT WILL HAPPEN WITH
VISIBILITIES AFTER THE PASSAGE OF A COLD FRONT IS LOW. SPEAKING OF
THE COLD FRONT IT IS EXPECTED TO REACH KCTB BY 00Z...KGTF/KHLN
AROUND 03Z...AND KHVR/KLWT/KBZN AROUND 06Z. GUSTY SOUTHERLY WINDS
WILL DEVELOP IN ADVANCE OF THE FRONT AND WINDS SHOULD DIMINISH AFTER
THE PASSAGE OF THE FRONT. CONFIDENCE IN WIND DIRECTIONS AFTER THE
PASSAGE OF THE FRONT IS LOW. CONFIDENCE IS HIGHER THAT GUSTY
SOUTHWEST WINDS WILL DEVELOP OVER THE PLAINS NEAR THE END OF THE
PERIOD AT 18Z SUNDAY. EXPECT A FEW SHOWERS AND THUNDERSTORMS THIS
AFTERNOON INTO THIS EVENING. GUSTY WINDS TO NEAR 40 KTS WILL BE A
RISK WITH THUNDERSTORMS MAINLY OVER SOUTHWEST MONTANA LATE THIS
AFTERNOON AND EARLY EVENING. LATE TONIGHT INTO SUNDAY MORNING A BAND
OF SHOWERS IS EXPECTED TO MOVE EAST THROUGH THE AREA AND CAN NOT
RULE OUT AN ISOLATED THUNDERSTORM. OTHER THAN THE MVFR/IFR
CONDITIONS WITH SMOKE CONDITIONS WILL BE VFR. BLANK

&&

.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 658 AM MDT SAT AUG 29 2015/
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

&&

.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  86  53  71  47 /  10  20  10  10
HLN  89  56  79  44 /  20  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 UNTIL 9 PM MDT THIS EVENING FOR MTZ112-114-
116>118.

&&

$$

WEATHER.GOV/GREATFALLS


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