Area Forecast Discussion
Issued by NWS Glasgow, MT

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FXUS65 KGGW 310227
AFDGGW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GLASGOW MT
827 PM MDT THU OCT 30 2014

.SHORT TERM...FOR NORTHEAST MONTANA...TONIGHT THROUGH SATURDAY...
UPDATE...ADJUST CLOUD COVER UP TONIGHT FOR MOST AREAS.
TEMPERATURES ARE NEAR FORECAST LOWS HOWEVER WITH INCREASING WINDS
AND CLOUD COVER DO NOT EXPECT THEM TO FALL MUCH FURTHER OVERNIGHT. PROTON

PREVIOUS DISCUSSION...
BIGGEST CHALLENGE DURING THIS PERIOD WILL BE WHAT
HAPPENS OVER THE NEXT 6 TO 12 HOURS WITH THE LOW CLOUDS. THESE LOW
CLOUDS HAVE COVERED THE NE TWO-THIRDS OF THE CWA AND EXTEND EAST
INTO THE DAKOTAS. MODELS CONTINUE TO DIFFER ON THE SCENARIOS ON
WHEN WE CLEAR OUT WITH THE NAM FAMILIES SEEMING TO VERIFY SO FAR.
WILL LEAN HEAVILY ON THE NAM AND CONCEPTUAL MODELS.

OTHERWISE...UPPER RIDGE BUILDING OVER THE NORTHERN ROCKIES WHILE
CANADIAN SURFACE HIGH PUSHES INTO THE DAKOTAS. THIS WILL CREATE A
TIGHT PRESSURE GRADIENT TONIGHT AND FRIDAY. THUS A LAKE WIND
ADVISORY IS IN EFFECT FROM THIS EVENING THROUGH FRIDAY.

ON SATURDAY...A THERMAL RIDGE MOVES EAST ACROSS THE AREA WITH 850 MB
TEMPS REACHING THE MID TEENS *C BUT LACK OF MIXING WILL NOT
TRANSLATE MUCH OF THAT WARMTH TO THE GROUND. THEREFORE TEMPS ARE
EXPECTED TO REACH THE 50S NORTH WITH 60S SOUTH. TFJ

.LONG TERM...SATURDAY NIGHT THROUGH THURSDAY...

SPENT SOME TIME UPDATING THE FORECAST TODAY FOR THIS COMING LATE
WEEKEND STORM SYSTEM AS EXTENDED MODELS SHOW THE BEST CONSENSUS
THEN AND IT COULD BE OF SOME IMPACT TO THE AREA.

SOMEWHAT SIMILAR TO THE LAST STORM SYSTEM WHICH MOVED THROUGH THE
REGION LAST WEEKEND...THIS NEXT STORM SYSTEM MIGHT HAVE JUST A
LITTLE MORE STRENGTH TO IT. THE UPPER-LEVEL TROUGH SEEMS STRONGER
AND DIGS DEEPER INTO THE WEST COAST AND INTER-MOUNTAIN WEST
REGIONS ON SATURDAY...THEN EJECTS NORTHEAST-WARD OVER CENTRAL
MONTANA BY SUNDAY MORNING. THE NORTHWESTERN SECTOR OF THIS STORM
SYSTEM WILL BE THE AREA MOST FAVORED FOR SNOW POTENTIAL AND THIS
IS EXPECTED TO TRACK MAINLY OVER OUR WESTERN...NORTHWESTERN...AND
NORTHERN ZONES THROUGH MONDAY MORNING. IT WILL LIKELY BEGIN AS A
RAIN AND SNOW MIX OVERNIGHT SATURDAY NIGHT INTO VERY EARLY SUNDAY
MORNING WITH THE BEST CHANCES FOR SNOW COMING IN BY OVERNIGHT SUNDAY
NIGHT. A SHORT-WAVE RIDGE MOVES THE STORM SYSTEM EAST OF NORTHEAST
MONTANA BY MONDAY NIGHT. BEST ESTIMATES FOR SNOW AT THIS TIME PLACES
2 TO 4 INCHES OVER THE HIGHER ELEVATIONS OF THE LITTLE ROCKIES...1
TO 3 INCHES NEAR OPHEIM...AND UNDER 1 INCH ELSEWHERE. MAY BE
ENOUGH TO CONSIDER A WINTER WEATHER ADVISORY FOR SOME LOCATIONS...BUT
IT IS STILL 4 DAYS AWAY FROM NOW AND TOO EARLY TO CALL. BMICKELSON

PREVIOUS LONG TERM DISCUSSION...THE EXTENDED PERIOD BEGINS SATURDAY EVENING
WITH A LONG WAVE RIDGE ENTERED OVER THE MISSISSIPPI RIVER VALLEY
AND AN UPPER LEVEL TROUGH DIGGING INTO THE WEST. A COLD FRONT AND
SURFACE CLOSED LOW WILL MOVE INTO NORTHEAST MONTANA SATURDAY NIGHT
TO INITIATE A PATTERN CHANGE. BOTH THE EC AND THE GFS SUGGEST A
WET AND COLD SUNDAY AND SUNDAY NIGHT WITH THE STORM MOVING OUT OF
THE AREA MONDAY AFTERNOON AND EVENING. COLD ARCTIC AIR GETS
WRAPPED IN BEHIND THE FRONT TO CHANGE SOME OF THE RAIN OVER TO
SNOW SUNDAY NIGHT. SO TEMPERATURES WILL DROP ABOUT 15F DEGREES ON
SUNDAY AND FURTHER ON MONDAY. READJUSTED QPF AND SNOW AMOUNTS.
SOUTHWEST PHILLIPS AND NORTHERN VALLEY COUNTIES NOW ARE SHOWING
SEVERAL INCHES OF SNOW AND MAY NEED A WATCH WHEN IT SHIFTS INTO
THE SHORT TERM.

AS THE CLOSED SURFACE LOW MOVES OVER NEMONT EASTERLY WIND WILL
BACK TO THE NORTH AND RAMP UP SATURDAY NIGHT AND BECOME
NORTHWESTERLY ON SUNDAY AND MONDAY. CAA WILL LIKELY PUSH WIND
HIGHER THAN MODEL GUIDANCE CURRENTLY SUGGESTS.

MODELS THEN SUGGEST WEAK RIDGING OR ZONAL FLOW THROUGH MID WEEK
WITH TEMPERATURES TRENDING TO NEAR NORMAL.

&&

.AVIATION...
LOW STRATUS MAY CONTINUE TO PROVIDE MVFR OR EVEN BORDERLINE IFR
CEILINGS THROUGH AT LEAST 06Z. THE TREND WILL BE TOWARD VFR
CONDITIONS BY MORNING THOUGH SOME HIGH CLOUDINESS MAY PERSIST.
EXPECT WINDS TO CONTINUE FROM THE SOUTHEAST AT 15-25KTS THROUGH
MORNING. MALIAWCO


&&

.GLASGOW WATCHES/WARNINGS/ADVISORIES...
LAKE WIND ADVISORY UNTIL 6 PM MDT FRIDAY FOR FORT PECK LAKE FOR
CENTRAL AND SOUTHERN VALLEY...GARFIELD...MCCONE.

&&

$$

WEATHER.GOV/GLASGOW





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