Area Forecast Discussion
Issued by NWS Glasgow, MT

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FXUS65 KGGW 311628
AFDGGW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GLASGOW MT
928 AM MST SAT JAN 31 2015

.SHORT TERM...FOR NORTHEAST MONTANA...TODAY THROUGH MONDAY...

SHORT TERM MODELS APPEAR TO HAVE AN EXCELLENT HANDLE ON THE
DEVELOPMENT OF SNOW OVER THE AREA WITH HRRR FORECASTS MATCHING THE
REFLECTIVITY PATTERN QUITE WELL. HEAVIEST PERIOD OF SNOW WILL LAST
THROUGH 20Z WITH LIGHTER MORE SCATTERED AMOUNTS TRAILING OFF
THROUGH 12Z TOMORROW. SNOW AMOUNTS HAVE BEEN AROUND AN INCH SO FAR
BUT BLOWING SNOW HAS REDUCED VISIBILITY DOWN TO 1/4 MILE IN PLACES.
COLD AND WIND HAS GENERATED SMALL DRY SNOW PARTICLES WHICH WILL
BLOW AND DRIFT DURING THE DAY. TEMPERATURES WILL CONTINUE TO
DECLINE THROUGH THE DAY REACHING SINGLE DIGITS BY SUNDAY MORNING.

UPDATED FORECAST FOR WINDS AS OBSERVATIONS HAVE BEEN RUNNING A
LITTLE HIGH.  MARTIN

PREVIOUS DISCUSSION...
LOW CLOUD AND FOG SPREADING SOUTHWEST ACROSS THE REGION. SHORTWAVE
PUSHING INTO NORTH CENTRAL MONTANA WITH SNOW STILL NORTH OF THE
CANADIAN BORDER. AS THE WAVE TRACKS THROUGH THE STATE TODAY...SNOW
WILL SPREAD SOUTHWARD...DISSIPATING THE FOG ALTHOUGH VISIBILITY
WILL REMAIN LOW WITH THE FALLING SNOW. ENOUGH GRADIENT WIND TO
PRODUCE SOME DRIFTING SNOW THIS AFTERNOON...BEFORE DIMINISHING
THIS EVENING. SNOWFALL ALSO EXPECTED TO TAPER OFF THROUGH THE
NIGHT. CURRENT ADVISORY STILL LOOKS ON TRACK WITH 2 TO 3 INCHES OF
SNOW EXPECTED TODAY...WITH AN ADDITIONAL INCH OR TWO TONIGHT.

COLD AIR LINGERS INTO SUNDAY AS CANADIAN HIGH SLIDES THROUGH THE
NORTHERN PLAINS. WEAK SHORTWAVE DROPPING THROUGH THE STATE SUNDAY
NIGHT SHIFTS ARCTIC BOUNDARY ACROSS CENTRAL MONTANA AND COULD
PRODUCE A LITTLE OVERRUNNING SNOW ON MONDAY MORNING. EBERT

.LONG TERM...MONDAY NIGHT THROUGH SATURDAY...

THE EXTENDED FORECAST PERIOD BEGINS WITH NORTHWEST FLOW ALOFT OVER
NORTHEAST MONTANA. THERE WILL BE A MODERATE RIDGE OFF THE WEST
COAST AND AN ARCTIC LOW CENTERED OVER HUDSON BAY BUT WITH A
MASSIVE COLD AIR MASS SPREAD OVER MOST OF CANADA. A WAVE MOVING
AROUND THE WESTERN SIDE OF THE LOW SENDS A COLD FRONT FURTHER
SOUTH INTO THE LOCAL REGION. A QUICK-MOVING SHORT-WAVE CROSSES
THE DIVIDE AND BECOME THE FOCUS OF PRECIPITATION MONDAY NIGHT AND
TUESDAY. AN INVERTED SURFACE TROUGH SUGGESTS QPF OF GREATER THAN
0.10 INCH. WX TYPE WILL LIKELY BE ALL SNOW...BUT THERE ARE HINTS
IN THE MODEL THAT SOME COULD BE IN THE FORM OF FREEZING RAIN MIXED
IN AT TIMES. MODEL QPF PRODUCES AROUND 3-4 INCHES OF SNOW FOR
TUESDAY. SO THIS IS A STORM TO WATCH.

A SURFACE HIGH SLIDES INTO THE AREA TUESDAY EVENING TO CUT OFF ANY
REMAINING SNOW. NEMONT WILL REMAIN ON THE COLD SIDE OF THE
STATIONARY BOUNDARY WITH MODIFIED ARCTIC AIR THAT WILL KEEP
TEMPERATURES SOMEWHERE NEAR NORMAL THROUGH THURSDAY. THEN AN UPPER
RIDGE AXIS MOVES ACROSS THE DIVIDE TO BRING A WARM FRONT THROUGH
NEMONT WHICH WILL RAISE TEMPERATURES ABOVE NORMAL FOR FRIDAY AND
SATURDAY. WHAT IS UNCERTAIN IS WHETHER OR NOT A DISTURBANCES RUNS
THROUGH THE REGION AFTER IT WARMS. THE GFS IS MORE ROBUST WITH A
WAVE THAN THE EC. SO THERE COULD BE SOME MIXED PRECIPITATION BY
THE WEEKEND. SCT

&&

.AVIATION...

AN UPPER LEVEL TROUGH MOVES EAST THROUGH THE AREA TODAY AS A COLD
FRONT DESCENDS SOUTH FROM CANADA BRINGING SNOW AND LOW CLOUDS FOR
IFR/LIFR CEILINGS AND VISIBILITIES AS LOW AS ONE-QUARTER MILE AT
TIMES. AIRPORT MINIMUMS ARE MOST LIKELY THIS MORNING THROUGH THIS
AFTERNOON. STRONG EASTERLY TO NORTHEASTERLY WINDS  WILL BEGIN TO
TAPER OFF LATE IN THE DAY. WIND WILL EASILY GENERATE AREAS OF
BLOWING SNOW. EXPECT CONDITIONS TO IMPROVE BY SUNDAY MORNING.
BMICKELSON

&&

.GLASGOW WATCHES/WARNINGS/ADVISORIES...
WINTER WEATHER ADVISORY UNTIL 5 AM MST SUNDAY FOR CENTRAL AND
SOUTHEAST PHILLIPS...CENTRAL AND SOUTHERN VALLEY...DANIELS...
DAWSON...EASTERN ROOSEVELT...GARFIELD...MCCONE...NORTHERN
PHILLIPS...NORTHERN VALLEY...PRAIRIE...RICHLAND...SHERIDAN...
SOUTHWEST PHILLIPS...WESTERN ROOSEVELT...WIBAUX.

&&

$$

WEATHER.GOV/GLASGOW




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