Area Forecast Discussion
Issued by NWS Glasgow, MT

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FXUS65 KGGW 022141
AFDGGW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GLASGOW MT
241 PM MST MON MAR 2 2015

.SHORT TERM...FOR NORTHEAST MONTANA...TONIGHT THROUGH WEDNESDAY...

...DANGEROUS WIND CHILLS OF 20 TO 40 BELOW WILL IMPACT NORTHEAST
MONTANA THIS EVENING THROUGH WEDNESDAY MORNING...

AFTER A PLEASANT MORNING ACROSS THE REGION WITH AMPLE SUNSHINE AND
TEMPERATURES IN THE 30S AND 40S...AN ABRUPT CHANGE IS NOW
UNDERWAY. A COLD FRONT WILL CONTINUE TO BRING INCREASING
CLOUDINESS AND GUSTY NORTHWEST WINDS ACROSS NORTHEAST MONTANA.
LIGHT SNOWFALL IS ALSO EXPECTED...THOUGH IT WILL BE OF THE HIT OR
MISS VARIETY. THE BETTER CHANCES FOR ACCUMULATING SNOWFALL WILL BE
OVER PETROLEUM COUNTY WHERE UP TO AN INCH IS EXPECTED. GUSTY WINDS
MAY CREATE BLOWING/DRIFTING SNOW CONDITIONS AND THUS IMPACT
VISIBILITY IN AREAS AFFECTED BY ANY SNOW.

TEMPERATURES WILL BE NEAR OR BELOW ZERO BY TUESDAY...WITH RECOVERY
TUESDAY AFTERNOON ONLY INTO THE SINGLE DIGITS. TUESDAY NIGHT WILL
FEATURE LOWS WELL BELOW ZERO. ALL THE WHILE...GUSTY WINDS WILL BE
RELENTLESS...SUSTAINED FROM THE NORTHWEST AT 15 TO 25
MPH...GUSTING AS HIGH AS 40 MPH AT TIMES. THIS WILL MAINTAIN THE
WIND CHILL HAZARD OVER THE REGION AND SO THE HEADLINES LOOK SOLID.

ONE THING TO CONSIDER IS THE UNCERTAINTY WITH REGARD TO LOWS
WEDNESDAY MORNING. LATEST 12Z MODELS CONTINUE TO FEATURE 850MB
TEMPERATURES AROUND -27C NEAR THE NORTH DAKOTA BORDER AT THIS
TIME. LACK OF SNOW COVER AND PERSISTENT WINDS MAY LIMIT THE
OVERALL EXTENT OF THE TEMPERATURE DROP. ADDITIONALLY...AS SKY
CONDITIONS CLEAR...THE TIMING OF THIS WILL BE CRITICAL. WHILE
850MB TEMPERATURES ARE COLDEST NEAR THE NORTH DAKOTA
BORDER...THESE LOCATIONS WILL BE THE LAST TO CLEAR OUT.
ALSO...SUNRISE IS STARTING TO GET A LITTLE EARLIER NOW. ALL OF
THESE THINGS CONSIDERED...CURRENT FORECAST LEANS ON THE COLDER
SIDE OF THE GUIDANCE ENVELOPE...THINKING THAT MODELS ARE
UNDERESTIMATING AN ANOMALOUS ARCTIC INTRUSION. BUT GIVEN THE
LIMITATIONS DISCUSSED...DID NOT GET TOO OVERLY AGGRESSIVE.

A FINAL NOTE...SHOULD FORECAST COME TO FRUITION AS EXPECTED...A
FEW PLACES NEAR THE CANADIAN BORDER WILL APPROACH IF NOT EXCEED
WIND CHILL WARNING THRESHOLDS. GIVEN THE CALVING SEASON UNDERWAY
THIS WILL NEED TO BE CONSIDERED...EVEN IF MARGINAL. THANKFULLY
THIS WILL ALL BE SHORT LIVED AS TEMPERATURES SLOWLY RECOVER ON
WEDNESDAY. MALIAWCO

.LONG TERM...WEDNESDAY NIGHT THROUGH MONDAY...
NO CHANGES WERE MADE. ONE THING OF NOTE WAS THE DISTURBANCE LATE
FRIDAY. 12Z ECMWF BROUGHT THE MOISTURE OVER THE CWA WHILE THE GFS
KEPT THE AREA DRY. DID NOT HAVE ENOUGH CONFIDENCE TO MAKE
ADJUSTMENTS. TFJ

PREVIOUS DISCUSSION...
THE NORTHWEST FLOW ALOFT WILL TRANSITION FROM AN ARCTIC ORIGIN TO
A PACIFIC ORIGIN BETWEEN WEDNESDAY AND THURSDAY. THIS WILL BRING A
WARMING TREND TO NORTHEAST MONTANA. THE ARCTIC AIRMASS MOVES TO
THE EAST WEDNESDAY NIGHT AS A WARM FRONT MOVES THROUGH THE AREA.
THE WARMING WILL BE AIDED BY CHINOOK WINDS ON THURSDAY WHICH WILL
RESULT IN TEMPERATURES BEING AS MUCH AS 30+ DEGREES WARMER THAN ON
WEDNESDAY. AT THIS POINT...THE FRONTAL PASSAGE IS EXPECTED TO BE
DRY. THE MILD AND DRY WEATHER WILL CONTINUE ON FRIDAY WITH A
SHORTWAVE RIDGE IN THE NORTHWEST FLOW ALOFT.

ECMWF AND GFS HAVE SIGNIFICANT DISAGREEMENTS ON THE TRACK OF A
SHORTWAVE TROUGH ACROSS THE REGION FRIDAY NIGHT AND SATURDAY. THE
ECMWF WANTS TO TAKE THE WAVE THROUGH WESTERN MONTANA AND IDAHO
WHILE THE GFS WANTS TO TAKE THROUGH SASKATCHEWAN AND NORTH DAKOTA.
AT THIS POINT... IT LOOKS LIKE EITHER SCENARIO BRING A WEAK COLD
FRONT THROUGH NORTHEAST MONTANA WITH THE MOISTURE TRACKING EITHER
TO THE WEST OR TO THE EAST OF THE FORECAST AREA. WILL KEEP
FORECAST DRY WITH SLIGHTLY COOLER TEMPERATURES ON SATURDAY.

NORTHWEST FLOW ALOFT CONTINUES SUNDAY AND MONDAY WITH MODELS
TIMING WAVES DIFFERENTLY. NOT MUCH IN THE WAY OF MOISTURE AT THIS
POINT. WILL MAINTAIN DRY FORECAST. FORRESTER

&&

.AVIATION...
FLIGHT CATEGORY: MOSTLY VFR. ISOLATED SNOW FLURRIES THIS EVENING
COULD BRIEFLY BRING MVFR CONDITIONS. SOME CLEARING IS POSSIBLE
TUESDAY MORNING WITH ANOTHER CHANCE OF FLURRIES MOVES IN DURING
THE AFTERNOON.

SYNOPSIS: NW WINDS WILL CONTINUE THROUGH TONIGHT AT SPEEDS MAINLY
20 TO 25 KTS. TFJ

&&

.GLASGOW WATCHES/WARNINGS/ADVISORIES...
WIND CHILL ADVISORY FROM 7 PM THIS EVENING TO NOON MST WEDNESDAY
FOR CENTRAL AND SOUTHEAST PHILLIPS...CENTRAL AND SOUTHERN
VALLEY...DANIELS...DAWSON...EASTERN ROOSEVELT...GARFIELD...
MCCONE...NORTHERN PHILLIPS...NORTHERN VALLEY...PETROLEUM...
PRAIRIE...RICHLAND...SHERIDAN...SOUTHWEST PHILLIPS...WESTERN
ROOSEVELT...WIBAUX.

&&

$$

WEATHER.GOV/GLASGOW




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