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AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
1145 PM MDT FRI SEP 4 2015

AVIATION SECTION UPDATED

.DISCUSSION... 
MINOR ADJUSTMENTS HAVE BEEN MADE TO THE POP AND 
WEATHER GRIDS. DETAILS OF CURRENT FORECAST REMAIN VALID. MAIN BAND 
OF PRECIPITATION HAS SHIFTED WEST OF GREAT FALLS AND REMAINS ALONG 
THE ROCKY MOUNTAIN FRONT. RAP13 ANALYSIS INDICATES THIS BAND WILL 
INCREASE IN AREAL COVERAGE AND MOVE BACK TO THE EAST WITHIN THE NEXT 
FEW HOURS. TEMPERATURES LOOK GOOD AND SHOW LITTLE DIURNAL CHANGE.

&&

.AVIATION... 
UPDATED 0545Z. 
A DISTURBANCE ALOFT WILL CONTINUE TO PUMP MOISTURE 
ACROSS WESTERN AND SOUTHWEST MONTANA RESULTING IN BANDS OF RAIN 
MOVING ACROSS CENTRAL MONTANA. RAIN MAY BE HEAVY AT TIMES. MVFR 
CONDITIONS PREVAIL WITH AREAS OF IFR DUE TO LOW CEILINGS AND RAIN. 
MOUNTAINS OBSCURED. 

&&

.PREV DISCUSSION...ISSUED 220 PM MDT FRI SEP 4 2015

TONIGHT THROUGH SUNDAY...GOING FORECAST REMAINS RELATIVELY UNCHANGED 
FOR TONIGHT THROUGH SATURDAY NIGHT. BIG UPPER LEVEL TROUGH CONTINUES 
TO ROTATE EASTWARD ACROSS THE NORTHERN ROCKY MOUNTAINS WITH 
WIDESPREAD RAIN AND MOUNTAIN SNOWS EXPECTED. SNOW LEVELS REMAIN 
RELATIVELY CONSTANT TONIGHT AND SATURDAY BUT ARE EXPECTED TO DROP TO 
AROUND 6000 FEET IN GLACIER PARK AND TO AROUND 6500 FEET IN 
SOUTHWEST MONTANA LATE SATURDAY NIGHT. SNOW ACCUMULATION AMOUNTS FOR 
SATURDAY NIGHT AND EARLY SUNDAY COULD BRING ABOUT 2 INCHES TO LOGAN 
PASS WITH OTHER MAJOR PASSES ACROSS THE FORECAST AREA RECEIVING 
LITTLE OR NO ACCUMULATIONS AS ROAD TEMPERATURES REMAIN QUITE WARM. 
NWS OFFICES TO THE WEST AND SOUTH HAVE ISSUED SNOW ADVISORIES FOR 
HIGHER ELEVATIONS SATURDAY NIGHT AND EARLY SUNDAY BUT I WILL HOLD 
OFF FOR NOW AS IT APPEARS IMPACTS WILL BE RELATIVELY MINIMAL. 
BIGGEST CHANGE TO THE FORECAST WAS TO LOWER POPS AND QPF FOR SUNDAY 
AS NEWEST MODEL RUNS ACCELERATE THE SYSTEM NORTHEASTWARD FASTER THAN 
THEY HAD PREVIOUSLY SHOWED. WINDY CONDITIONS WILL DEVELOP IN THE 
WAKE OF THE STORM SYSTEM SUNDAY AFTERNOON BUT DO NOT ANTICIPATE THAT 
THEY WILL BE OVERLY STRONG AT THIS TIME. MPJ

SUNDAY NIGHT THROUGH FRIDAY...DEEP UPPER-LEVEL TROF THAT WILL BRING 
WIDESPREAD RAINFALL THIS WEEKEND WILL MOVE INTO ALBERTA/SASKATCHEWAN 
BY SUNDAY NIGHT. A FEW RESIDUAL SHOWERS WILL BE POSSIBLE ALONG THE 
HI-LINE COUNTIES AND OVER THE ROCKY MTN FRONT AS THE SYSTEM EXITS, 
BUT MOST OF OUR REGION WILL REMAIN DRY INTO MON MORNING.  A WEAK 
SECONDARY TROF IS FORECAST TO SWING INTO THE NORTHERN ROCKIES MON 
AFTN/EVE GENERATING SOME SPOTTY, LIGHT RAIN SHOWERS MAINLY 
ALONG/WEST OF THE INTERSTATE 15 CORRIDOR. MODELS ARE IN GOOD 
AGREEMENT THAT HIGH PRESSURE RIDGE WILL STEADILY DEVELOP ALONG THE 
WEST COAST NEXT WEEK. THE RESULTING WEST-NORTHWEST FLOW ALOFT OVER 
MONTANA WILL KEEP CONDITIONS DRY ACROSS THE REGION WITH GRADUALLY 
WARMING TEMPERATURES. WARANAUSKAS

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  47  53  44  61 /  90  80  90  40 
CTB  44  49  41  57 /  90  90  90  50 
HLN  44  58  40  64 / 100  80  80  40 
BZN  45  66  39  63 /  70  60  60  30 
WEY  37  60  22  54 /  40  20  50  20 
DLN  42  59  34  58 /  70  60  60  20 
HVR  48  58  44  59 /  80  60  90  50 
LWT  47  61  39  61 /  80  40  80  30 

&&

.TFX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

WEATHER.GOV/GREATFALLS

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