High Wind in Montana, November 13, 2015

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
1050 AM MST FRI NOV 13 2015

...UPDATE TO AVIATION SECTION...

.UPDATE...WINDY CONDITIONS WILL CONTINUE ACROSS MUCH OF THE
FORECAST AREA TODAY. HAVE SO FAR VERIFIED THE HIGH WIND WARNING IN
THE NORTHERN ROCKY MOUNTAIN FRONT AND HAD AN ISOLATED GUST REACH
CRITERIA IN EASTERN TETON COUNTY. HOWEVER, NEITHER THE SOUTHERN
ROCKY MOUNTAIN FRONT NOR EASTERN GLACIER COUNTY HAVE VERIFIED.
STRONGEST WINDS ALOFT ARE EXPECTED AROUND 21Z THIS AFTERNOON SO
THERE IS STILL A CHANCE THESE ZONES MAY ALSO HIT CRITERIA. IT
REMAINS POSSIBLE, ALSO, THAT THE NORTHERN RMF MAY NEED TO BE
EXTENDED THROUGH THE NIGHT AS LATEST MODEL CROSS-BARRIER FLOW
SUGGESTS STRONG WINDS REMAIN POSSIBLE IN THIS ZONE THROUGH
SATURDAY MORNING. CONSIDERED MAKING THE EXTENSION IN TIME WITH
THIS UPDATE BUT OPTED TO HOLD OFF, MAINLY BECAUSE OF THE LACK OF
VERIFICATION FOR THE OTHER ZONES IN THE WARNING. HAVE MADE SOME
MINOR TWEAKS TO WINDS FOR TODAY AND TONIGHT BASED ON LATEST MODELS
AND HAVE ALSO UPDATED SKY CONDITIONS TO BE MORE IN KEEPING WITH
SATELLITE IMAGERY AND NEWEST MODELS. TEMPERATURES AND POPS/WEATHER
LOOK GOOD AT THIS TIME SO NO FURTHER UPDATES ARE ANTICIPATED. MPJ

&&

.AVIATION...
UPDATED 1750Z.
VFR CONDITIONS EXPECTED THROUGH 18Z SATURDAY. AS WITH THE LAST
COUPLE OF DAYS...FAST WESTERLY FLOW ALOFT WILL CONTINUE TO LEAD TO
GUSTY WINDS AT THE SFC THROUGH AT LEAST 06Z/SATURDAY AND ESPECIALLY
ALONG THE ROCKY MOUNTAIN FRONT AND EAST INTO THE PLAINS OF CENTRAL
MONTANA. BEYOND THAT POINT...THE WIND SHOULD GRADUALLY BEGIN TO
DECREASE SOME. SCT/BKN MID AND UPPER LEVEL CLOUDS WILL CONTINUE TO
MOVE ACROSS THE REGION THROUGH THE TAF PERIOD. WHILE NO
PRECIPITATION IS EXPECTED AT ANY TAF SITE THROUGH SATURDAY
MORNING...RAIN AND SNOW SHOWERS ARE LIKELY RIGHT ALONG THE NORTHERN
ROCKY MOUNTAIN FRONT WITH LOWER CLOUDS AND POSSIBLE MOUNTAIN
OBSCURATIONS. MARTIN

&&

.PREV DISCUSSION...
/ISSUED 430 AM MST FRI NOV 13 2015/
TODAY THROUGH SUNDAY EVENING...LATEST ANALYSIS SHOWS THE NORTHERN
ROCKIES AREA SQUARELY IN THE TIGHT GRADIENT ZONE BETWEEN A DEEP LOW
PRESSURE SYSTEM CENTERED IN THE NORTHERN GULF OF ALASKA AND A
FLATTENED HIGH PRESSURE RIDGE EXTENDING FROM THE FOUR CORNERS AREA
BACK INTO THE EASTERN PACIFIC OFF THE CALIFORNIA COAST. THE
RESULTING STRONG WINDS ALOFT (70-80 MPH) HAVE COMBINED WITH A
STRENGTHENING LEESIDE TROF THAT EXTENDS FROM NORTHERN ALBERTA TO
SOUTH CENTRAL MT TO CREATE SURFACE WIND GUSTS OF 50-80 MPH FROM EAST
GLACIER TO GREAT FALLS FROM YESTERDAY EVENING INTO THIS MORNING.
LATEST FORECAST MODEL RUNS CONTINUE TO SHOW THIS TIGHT GRADIENT
PATTERN PERSISTING THROUGH THIS EVENING, SO HAVE DECIDED TO ADD
EASTERN GLACIER COUNTY INTO THE ONGOING HIGH WIND WARNING FOR THE
ROCKY MTN FRONT.  FURTHER EAST INTO THE CENTRAL AND HILINE COUNTIES,
MODELS ARE STILL KEEPING PEAK WINDS JUST BELOW WARNING CRITERIA, BUT
THIS WILL BE CLOSELY MONITORED THROUGH TODAY IN CASE ADDITIONAL
AREAS NEED TO BE INCLUDED IN THE WARNING.

OUR REGION WILL GET A BREAK FROM THE HIGH WINDS ON SATURDAY AS A
MODERATELY STRONG UPPER-LEVEL TROF DEVELOPS SOUTHWARD ALONG THE
PACIFIC COAST. THIS WILL INDUCE THE FOUR CORNERS RIDGE TO AMPLIFY
NORTHWARD THROUGH MT AND SHIFT THE TIGHT GRADIENT AREA TOWARD THE
IDAHO PANHANDLE AND SOUTHWEST CANADA. WINDS ALOFT WILL TURN TO THE
SOUTHWEST, BRINGING WARMER TEMPERATURES AND MAINTAINING DRY
CONDITIONS ACROSS THE AREA, EXCEPT FOR SCATTERED SHOWERS ALONG THE
NORTHERN ROCKY MTN FRONT. THE TROF TURNS INLAND LATE SAT NIGHT
AND MAKES STEADY EASTWARD PROGRESS ON SUNDAY, WITH ITS LEADING
EDGE OF CLOUDS AND PRECIPITATION REACHING THE CONTINENTAL DIVIDE
BY SUN EVENING. TEMPS WILL REMAIN ABOVE NORMAL ACROSS THE FORECAST
AREA, WITH HIGHS IN MID 40S TO MID 50S EXPECTED FRI THROUGH SUN.
WARANAUSKAS

SUNDAY NIGHT THROUGH SATURDAY...THE PERIOD BEGINS WITH A
LONGWAVE TROUGH OVER THE NORTHWESTERN US. THE TROUGH FRACTURES
WITH AN ALBERTA CLIPPER FORMING IN THE NORTH WHILE THE SOUTHERN
PORTION DIGS ACROSS THE GREAT BASIN. THE RESULT IS ANOTHER ROUND
OF STRONG WINDS EARLY MONDAY AS THE NORTHERN CLIPPER DEPARTS AND
ITS ASSOCIATED UPPER TROUGH AXIS CROSSES CENTRAL MONTANA.
TEMPERATURES TURN COOLER ON MONDAY. DOWNSLOPE WINDS LIMIT
PRECIPITATION ON MONDAY FOR NORTH CENTRAL MT...BUT A FEW INCHES OF
SNOW WILL BE POSSIBLE OVER THE SOUTHWEST MOUNTAINS.

MODEL SOLUTIONS DIVERGE MONDAY NIGHT INTO TUESDAY AS A SIGNIFICANT
STORM SPINS UP TO THE SOUTH OVER THE CENTRAL ROCKIES. THE GFS
PRESENTS NORTHERLY FLOW ALOFT WITH SURFACE HIGH PRESSURE OVER
SOUTHWEST MT. THE ECMWF MAINTAINS A BRISK WESTERLY FLOW WITH A
CONTINUING PERIOD OF POWERFUL DOWNSLOPE SURFACE WINDS. HAVE ACCEPTED
A MODEL BLEND WITH WINDY CONDITIONS TUESDAY NIGHT AND TEMPERATURES
WARMING CLOSE TO AVERAGE ON WEDNESDAY.

ON THURSDAY THE SEASONS FIRST SURGE OF ARCTIC AIR APPEARS ON THE
NORTHWEST HORIZON EVEN AS MODEL SOLUTIONS CONTINUE TO SEPARATE
DOWNSTREAM OVER THE CENTRAL AND EASTERN U.S. TEMPERATURES TREND
COLDER THURSDAY THROUGH SATURDAY WITH A GOOD CHANCE FOR SNOW
SOMETIME ON THURSDAY OR FRIDAY. HAVE PRESENTED A RATHER CONSERVATIVE
FORECAST SINCE CONFIDENCE IS LOW WITH REGARD TO TIMING OF POSSIBLE
WINTER WEATHER AND TEMPERATURES. PN

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  51  37  55  35 /  10  10   0  10
CTB  48  34  51  31 /  10  10  10  10
HLN  49  32  51  32 /  10  10  10  10
BZN  44  26  47  26 /  10  10  10  10
WEY  31  17  36  19 /  20  10   0   0
DLN  40  27  43  28 /  10  10  10  10
HVR  55  37  58  33 /  10   0   0  10
LWT  54  37  58  37 /   0   0   0  10

&&

.TFX WATCHES/WARNINGS/ADVISORIES...
HIGH WIND WARNING UNTIL 11 PM MST THIS EVENING FOR MTZ009-010-
048.

&&

WEATHER.GOV/GREATFALLS

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE GREAT FALLS MT
735 AM MST FRI NOV 13 2015

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0130 AM     NON-TSTM WND GST BABB                    48.86N 113.44W
11/13/2015  M91 MPH          GLACIER            MT   TRAINED SPOTTER

            GUST MEASURED ON WEATHER STATION. WINDS ARE STILL GUSTY
            AT THIS TIME BUT HAVE COME DOWN SOME.

&&

MARTIN

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE GREAT FALLS MT
934 AM MST FRI NOV 13 2015

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0223 AM     NON-TSTM WND GST 4 SSW POWER             47.66N 111.72W
11/13/2015  M76 MPH          TETON              MT   TRAINED SPOTTER

            PEAK GUST MEASURED ON DAVIS WEATHER STATION. AS OF 930
            AM THE WIND WAS STILL GUSTING UP TO 62 MPH

&&

MARTIN