285
FXUS63 KFGF 181152
AFDFGF
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND FORKS ND
552 AM CST MON NOV 18 2024
KEY MESSAGES
- WIDESPREAD RAINFALL, HEAVY AT TIMES, OVERSPREADS EASTERN
NORTH DAKOTA AND MINNESOTA MONDAY EVENING INTO TUESDAY.
- ACCUMULATING SNOW AND GUSTY WINDS WILL BRING WINTER IMPACTS TUESDAY
NIGHT INTO WEDNESDAY.
- UNCERTAINTY STILL EXISTS IN SEVERITY AND LOCATION OF WINTER
IMPACTS, WITH MAIN UNCERTAINTY TIED TO STRENGTH AND EVOLUTION
OF LOW PRESSURE SYSTEM.
- HIGHEST CHANCE TO RECEIVE WINTER STORM IMPACTS (SNOWFALL 6
INCHES OR MORE) WILL BE DEVILS LAKE REGION WHERE CONFIDENCE IS
55-80 PERCENT OF WINTER STORM IMPACTS.
DISCUSSION
ISSUED AT 320 AM CST MON NOV 18 2024
..SYNOPSIS
ONE UPPER LEVEL WAVE IS OVER IDAHO, NORTHWEST MONTANA AND MOVING
INTO SOUTHERN ALBERTA. THIS WILL MOVE INTO SOUTHERN INTO EAST
CENTRAL SASKATCHEWAN THE NEXT 24 HOURS. A STRONG 500 MB LOW WAS
NEAR EL PASO TEXAS AND THIS WAVE WILL MOVE NORTH INTO SOUTHERN
MN BY 12Z TUE WITH AN ACCOMPANYING SURFACE LOW IN SW MN. AS THIS
SFC LOW PRESSURE SYSTEM MOVES NORTH THRU FAR WESTERN MN INTO SE
MANITOBA TUES NIGHT, THE UPPER WAVE WITH THIS WILL COMBINE WITH
THE SASKATCHEWAN UPPER WAVE AND FORM A LARGER UPPER LOW OVER
NORTHERN ND TUES OVERNIGHT. THE STRENGTH AND TRACK OF THIS
SYSTEM WILL PLAY A HUGE ROLE IN PRECIPITATION AMOUNT, TYPE AND
LOW LEVEL TEMPERATURES.
..WIDESPREAD RAINFALL MONDAY NIGHT INTO TUESDAY
STRONG MOISTURE ADVECTION WILL OCCUR NORTHWARD WITH THIS WAVE
AND BRING A WIDESPREAD RAIN EVENT TO THE AREA. QPF WITH THIS
SYSTEM HAS BEEN INCREASING WITH WPC QPF VALUES OVER 1 INCH OVER
NEARLY ALL OF THE FORECAST AREA WITH POTENTIAL 1.50 INCHES
WITHIN THE RRV.
..POTENTIAL WINTER IMPACTS AND ASSOCIATED UNCERTAINTY
THE INTERACTION AND EVENTUAL MERGER OF THE AFOREMENTIONED TWO
UPPER WAVES BRINGS INHERENT UNCERTAINTY IN THEIR EVOLUTION IN
PARTICULARLY IN REGARDS TO THE DEGREE OF WRAPAROUND SNOW AND LOW
LEVEL COLD ADVECTION. THE MAIN FORCING (FRONTOGENETICAL) AND 850
MB WARM ADVECTION WILL TARGET HEAVY SNOW RATES IN WESTERN
MANITOBA AND EASTERN SASKATCHEWAN TUESDAY. AS UPPER LOW
CONSOLIDATES IN NORTH CENTRAL AND NORTHEAST ND TUESDAY NIGHT AND
MOVES EAST-SOUTHEAST TO NEAR BEMIDJI 18Z WEDNESDAY THE ISSUE
WILL BE DEGREE OF WRAPAROUND SNOWFALL AND INTENSITY AND ALSO ANY
MESOSCALE INFLUENCES, AS PORTRAYED BY MOST GUIDANCE IN SHOWING A
HEAVIER SIGNAL OF QPF (SNOW) IN WESTERN MN JUST EAST OF GRAND
FORKS TO JUST EAST OF FARGO. THE DEGREE OF COOLING TO TURN RAIN
TO SNOW TUESDAY NIGHT INTO THE RRV AND MN ALSO IS HIGHLY
UNCERTAIN. LIKELY TO SEE VARIOUS PRECIP TYPES DUE TO LOCAL
COOLING WHERE SOME LOCATIONS GO TO SNOW EARLIER THAN SOME.
PARTICULARLY TRUE WHERE WITH IN THE IMMEDIATE RED RIVER VALLEY
TEMPS MAY HOLD 1-2 DEGREES HIGHER THAN EAST AND WEST OF THE
VALLEY RESULTING IN A LOCALIZED LOWER SNOWFALL ACCUMULATION.
THEREFORE RANGES FOR SNOWFALL REMAIN QUITE LARGE WITH 10/90
PERCENTILES INDICATE LOW END OF 0 SNOW AND HIGH END OF 6-8
INCHES WITHIN THE RRV AND ADJACENT WESTERN MN.
PROB OF 6 INCHES OF SNOW OR MORE ARE HIGHEST IN DEVILS LAKE
BASIN AND PROBS OF SUCH ARE IN THE 55-80 PERCENT RANGE FROM WPC
AND ALSO NBM LEADING TO HIGHER CONFIDENCE IN WINTER STORM WATCH
ISSUANCE FOR FAR NORTHWEST FCST AREA (BENSON, RAMSEY, TOWNER,
CAVALIER COUNTIES). CHAT WITH WPC AND BIS INDICATED ENOUGH
CONFIDENCE FOR A WATCH FROM PARTS OF TUESDAY INTO WED FOR NORTH
CENTRAL ND AND INTO DVL REGION.
WINDS WILL PLAY A ROLE WITH CHANCES OF SEEING WIND GUSTS 45 MPH
OR HIGHER 40-60 PERCENT DEVILS LAKE TO COOPERSTOWN TO VALLEY
CITY AREA. THIS WIND COMBINED WITH FALLING SNOW WILL CAUSE
REDUCED VSBYS.
WAY TOO UNCERTAIN IN REGARDS TO PTYPE AND SNOW AMOUNTS OUTSIDE
OF THE DVL BASIN. INITIAL THOUGHTS ARE ADVISORY LIKELY TO BE
NEEDED, BUT THAT CAN WAIT TIL CONFIDENCE HAS INCREASED FOR WHAT
LOCATIONS.
AVIATION /12Z TAFS THROUGH 12Z TUESDAY/
ISSUED AT 551 AM CST MON NOV 18 2024
FOR DAYTIME HOURS TODAY, CONDITIONS WILL BE VFR WITH A SOUTH-
SOUTHEAST WIND UP TO 10 KTS. THINGS GO DOWNHILL QUICK THIS
EVENING AND OVERNIGHT AS RAIN OVERSPREADS THE AREA FROM SOUTH TO
NORTH. WITH THAT LIKELY IFR CEILINGS AFTER MIDNIGHT THRU 12Z TUE
(AND BEYOND) AND MVFR OR IFR VSBYS IN RAIN/FOG.
FGF WATCHES/WARNINGS/ADVISORIES
ND...WINTER STORM WATCH FROM TUESDAY AFTERNOON THROUGH WEDNESDAY
AFTERNOON FOR NDZ006-007-014-015.
MN...NONE.
DISCUSSION...RIDDLE
AVIATION...RIDDLE
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