Area Forecast Discussion
Issued by NWS Glasgow, MT

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FXUS65 KGGW 010343
AFDGGW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GLASGOW MT
843 PM MST SAT JAN 31 2015

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

UPDATE...
WILL KEEP THE ADVISORY GOING UNTIL 11PM FOR THE AFFECTED
AREA...THEN TAPPER OFF TO FLURRIES FOR THE OVERNIGHT WHICH IS
SUPPORTED BY UPSTREAM CANADIAN RADARS. BASED ON CURRENT TRENDS HAD
TO LOWER TEMPERATURES FOR ALL AREAS AS FORECAST LOWS WERE BEING
SURPASSED ALREADY THIS EVENING.       PROTON

PREVIOUS DISCUSSION...
WIDESPREAD SNOW IS EXPECTED TO CONTINUE THIS EVENING...ALTHOUGH A
GRADUAL DIMINISHING TOWARD FLURRIES IS MOST LIKELY THROUGH THE
OVERNIGHT HOURS AS MOST MODEL DATA LEANS TOWARD THIS FORECAST
CONSENSUS. AS NEW SNOWFALL WILL BE VERY MINIMAL AND WINDS WILL
DIMINISH BELOW 15 KNOTS AFTER 06Z...WE FELT IT WAS BEST TO CUT BACK
THE END TIME OF THE WINTER WEATHER ADVISORY TO 06Z. THOUGHTS ARE
THAT VISIBILITY WILL BE GREATLY IMPROVED BY THEN DUE TO THE
ABOVE MENTIONED EXPECTED CONDITIONS.

BY EARLY SUNDAY MORNING...AROUND 12Z ONLY VERY LIGHT FLURRIES IF
ANY AT ALL ARE EXPECTED OVER OUR SE ZONES...WITH CLEARING SKIES
ELSEWHERE. WINDS WILL BECOME LIGHT AND VARIABLE IT NOT CALM. THIS
QUICK CHANGE IN WEATHER CONDITIONS WILL BE THANKS TO A QUICK
PASSING SHORT-WAVE RIDGE PUSHING THROUGH THE NORTHERN ROCKIES ON
SUNDAY. BY SUNDAY AFTERNOON AND EVENING...ANOTHER DISTURBANCE IN
THE GENERAL NW FLOW ALOFT WILL BRING SOME LIGHT SCATTERED SNOW
SHOWERS TO NE LATE SUNDAY NIGHT. BMICKELSON

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

FOLLOWING AN INTERLUDE OF NO PCPN ON SUNDAY...SNOW RETURNS MONDAY
IN RESPONSE TO SMALL IMPULSES EMBEDDED IN NORTHWEST FLOW AND A
RELATED FROPA MONDAY AFTERNOON. PERIODS OF LIGHT SNOW ARE EXPECTED FROM
MONDAY MORNING THROUGH TUESDAY. TOTAL ACCUMULATIONS OF 2 TO 4
INCHES ARE POSSIBLE FOR THIS PERIOD. FOLLOWING MONDAY`S
FROPA...TEMPERATURES WILL BE NORMAL TO BELOW NORMAL IN THE WAKE OF
COLD AIR ADVECTION AND WITH SOME HELP FROM NEW SNOW COVER. SNOW
COVER COULD LEAD TO EVEN LOWER TEMPERATURES THAN CURRENT MODELS
INDICATE IF HANDLING OF SNOW COVER IS IMPERFECT. HOWEVER...GFS
SPAGHETTI AND EC SHOW RIDGE CONDITIONS RETURNING TO THE WESTERN CONUS
THURSDAY ONWARD...WITH TEMPS BACK TO THE UPPER 30S AND 40S
THURSDAY ONWARD AND MUCH LOWER CHANCES FOR PCPN. MARTIN
PREVIOUS LONG TERM DISCUSSION...
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...
LIGHT SNOW WILL GRADUALLY DIMINISH OVERNIGHT. MVFR TO IFR CIGS AND
VSBYS WILL RETURN TO VFR BY SUNDAY MORNING ACROSS ALL TERMINAL
LOCATIONS AS THE SNOW MAKES ITS DEPARTURE. NORTHEAST WINDS OF
AROUND 10 KTS WILL TREND TOWARD LIGHT AND VARIABLE AFTER 06Z
ACROSS KGGW AND KOLF AND AFTER 09Z AT KSDY AND KGDV. MALIAWCO


&&

.GLASGOW WATCHES/WARNINGS/ADVISORIES...
WINTER WEATHER ADVISORY UNTIL 11 PM MST THIS EVENING 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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