Area Forecast Discussion
Issued by NWS Great Falls, MT

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FXUS65 KTFX 270939
AFDTFX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
339 AM MDT THU AUG 27 2015

.DISCUSSION...
THURSDAY THROUGH SATURDAY...FIRE WEATHER CONCERNS WILL BE THE
MAJOR IMPACT THIS THROUGH THE FIRST PART OF THE WEEKEND AS GUSTY
WINDS AND LOW RELATIVE HUMIDITY LEVELS ON THE LEE SIDE OF THE
ROCKY MOUNTAIN FRONT WILL CREATE CRITICAL AND NEAR CRITICAL FIRE
WEATHER CONCERNS TODAY. MONSOONAL MOISTURE WILL CONTINUE TO MOVE
INTO THE AREA TODAY BRINGING AN INCREASE POTENTIAL FOR
THUNDERSTORMS AND AN INCREASE IN FIRE STARTS FROM LIGHTNING AND
GUSTY WINDS NEAR THUNDERSTORMS. DRY AND WARM CONDITIONS WILL
CONTINUE THROUGH THE DAY SATURDAY WITH WINDS INCREASING AHEAD OF A
DRY COLD FRONT THAT WILL MOVE THROUGH THE AREA BRINGING GUSTY
WINDS AND LOW HUMIDITY VALUES AHEAD OF THE FRONT. THE LACK OF
MOISTURE WITH THE FRONTAL PASSAGE WILL LIMIT SHOWER AND
THUNDERSTORM DEVELOPMENT...BUT THERE IS ALMOST NO SIGNIFICANT
PRECIPITATION EXPECTED WITH THIS FRONTAL PASSAGE. ADDITIONAL FIRE
WEATHER HIGHLITES MAY BECOME NECESSARY AS THIS FRONT APPROACHES.
SUK

SATURDAY NIGHT THROUGH THURSDAY...MEDIUM RANGE MODEL SOLUTIONS
REMAIN IN RELATIVELY GOOD AGREEMENT THROUGH MUCH OF THE FORECAST
PERIOD. HOWEVER, BOTH HAVE TRENDED TOWARD A SOMEWHAT DRIER FORECAST
SO HAVE AGREED WITH SURROUNDING OFFICES TO PULL BACK POPS A BIT. AS
NOTED YESTERDAY, THE MAIN PLAYERS IN THE FORECAST ARE AN UPPER LEVEL
TROUGH OVER THE GULF OF ALASKA/SOUTHEAST ALASKA AND RIDGING OVER THE
HIGH PLAINS. MONTANA REMAINS BENEATH AN SOMEWHAT UNSTABLE SOUTHWEST
FLOW ALOFT THROUGH THE PERIOD AND BOTH MODELS ATTEMPT TO SLOWLY
PROGRESS THE UPPER TROUGH INTO WESTERN CANADA. THE ECMWF IS A BIT
MORE AGGRESSIVE WITH THIS THAN THE GFS BUT IT APPEARS THAT BOTH
MODELS MAY BE OVERDOING HOW FAR EASTWARD THIS FEATURE CAN MOVE GIVEN
THE UPPER RIDGE AND THE VERY WARM LATE SUMMER TEMPERATURES THAT WILL
TEND TO SUPPORT RIDGE STABILITY OVER THE PLAINS. HAVE MADE ONLY
MINOR CHANGES TO THE GOING FORECAST PACKAGE, MAINLY TO EASE BACK ON
POPS AND SURFACE WIND SPEEDS. TEMPERATURES FROM MONDAY ONWARD ARE
EXPECTED TO BE NEAR OR SLIGHTLY ABOVE SEASONAL AVERAGES AS GUIDANCE
FROM BOTH MODELS SUPPORT COOLER TEMPERATURES THAN THOSE OF THIS
WEEK. MPJ



&&

.AVIATION...
UPDATED 0530Z.

WIDESPREAD VFR AND MVFR CONDITIONS WITH SOME MOUNTAIN OBSCURATION
WILL CONTINUE TO DUE TO SMOKE FROM THE REGIONAL WILDFIRES. MONSOONAL
MOISTURE WILL INCREASE DURING THE TAF PERIOD, SPREADING MID/HIGH
LEVEL CLOUDS NORTHEAST ACROSS THE AREA. A FEW THUNDERSTORMS WILL
DEVELOP AND MOVE OVER THE AREA THROUGH THURSDAY AFTERNOON AND
EVENING.  THE LIKELIHOOD IS LOW THAT ANY STORM WILL DIRECTLY IMPACT
A TAF SITE HOWEVER BRIEF WIND GUSTS TO 30 KT ARE POSSIBLE NEAR ANY
STORM. SUK

&&

.FIRE WEATHER...

WARM AND DRY CONDITIONS WILL CONTINUE THROUGH SATURDAY. WINDY
CONDITIONS ARE EXPECTED ALONG THE ROCKY MOUNTAIN FRONT AND
ADJACENT HIGH PLAINS. A RED FLAG WARNING IS IN EFFECT FOR FIRE
WEATHER ZONE 112. FURTHER SOUTH IN FIRE WEATHER ZONE 114 THERE IS
NOT AS MUCH CONFIDENCE THAT STRONG GUSTY WINDS WILL EXIST FOR A
SIGNIFICANT PERIOD OF TIME THIS AFTERNOON. HAVE LEFT THE FIRE
WEATHER WATCH IN PLACE AND WILL ALLOW THE SUBSEQUENT SHIFT TO VIEW
HIGH RESOLUTION MODELS BEFORE DECIDING ON ANY ADDITIONAL HIGHLITES
FOR ZONE 114. MONSOONAL MOISTURE WILL MOVE INTO THE REST OF THE
AREA AND COULD PRODUCE SOME ISOLATED SHOWERS AND THUNDERSTORMS
THIS AFTERNOON. A MIXTURE OF WET AND DRY THUNDERSTORMS ARE
EXPECTED. SATURDAY WILL BE ANOTHER NEAR CRITICAL FIRE WEATHER DAY
AS AN APPROACHING DRY COLD FRONT WILL CREATE THE POTENTIAL FOR
GUSTY WINDS WITH LITTLE TO NO MOISTURE ASSOCIATED WITH THE FRONT
ADDITIONAL HIGHLITES MAY BECOME NECESSARY AHEAD OF THE COLD FRONT.
SUK

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  90  58  90  64 /  20  10  10  10
CTB  87  53  87  57 /  10  10  10  10
HLN  89  53  89  55 /  30  20  10  10
BZN  86  50  88  53 /  50  20  10  10
WEY  76  37  80  41 /  70  40  10  10
DLN  84  48  86  54 /  40  20  10  10
HVR  91  57  90  58 /  20  10   0  10
LWT  87  56  88  59 /  40  10  10  10

&&

.TFX WATCHES/WARNINGS/ADVISORIES...
FIRE WEATHER WATCH FROM NOON MDT TODAY THROUGH THIS EVENING FOR
MTZ114.

RED FLAG WARNING FROM NOON TODAY TO 9 PM MDT THIS EVENING FOR
MTZ112.

&&

$$

WEATHER.GOV/GREATFALLS


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