784
FXUS63 KFGF 180533
AFDFGF
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND FORKS ND
1133 PM CST SUN NOV 17 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.
- A CLOSER AND STRONGER SYSTEM WOULD INCREASE SEVERITY OF WINTER
IMPACTS WITHIN EASTERN NORTH DAKOTA, POTENTIALLY SIGNIFICANT
AT TIMES, WITH LIMITED WINTER IMPACTS ELSEWHERE (20% CHANCE OF
OCCURRING). A SYSTEM THAT IS FURTHER AWAY AND WEAKER WOULD
BRING LESS SEVERE WINTER IMPACTS, BUT COVERAGE OF IMPACTS MAY
SPREAD OVER A LARGER AREA.
UPDATE
ISSUED AT 1133 PM CST SUN NOV 17 2024
THE QUIET BEFORE THE NEXT SYSTEM CONTINUES, WITH CLEAR SKIES, SOUTH
WINDS AND TEMPERATURES IN THE 30S.
UPDATE
ISSUED AT 939 PM CST SUN NOV 17 2024
A FEW STRAY CIRRUS CLOUDS LINGER, BUT OTHERWISE MOSTLY CLEAR AND
TEMPS HOLDING MOSTLY IN THE 30S.
UPDATE
ISSUED AT 619 PM CST SUN NOV 17 2024
VERY QUIET THIS EVENING WITH A FEW CIRRUS CLOUDS MOVING INTO
NORTHEASTERN NORTH DAKOTA. A FEW MINOR TWEAKS TO SKY GRIDS BUT
OTHERWISE NO CHANGES TO THE GOING FORECAST.
DISCUSSION
ISSUED AT 201 PM CST SUN NOV 17 2024
..SYNOPSIS
A STRONG UPPER LEVEL WAVE EJECTS NORTHWARD OUT OF THE SOUTHERN
PLAINS INTO THE UPPER MIDWEST AND SOUTH-CENTRAL TIER OF CANADA
MONDAY THROUGH WEDNESDAY. THIS WILL INTERACT WITH ANOTHER UPPER
WAVE MOVING THROUGH THE NORTHERN TIER OF THE CONUS BEFORE
MERGING WITH THE STRONG UPPER WAVE AROUND WEDNESDAY. THIS WILL
BRING WIDESPREAD PRECIPITATION, INITIALLY AS WIDESPREAD RAINFALL
STARTING LATE MONDAY TRANSITIONING TO AREAS OF SNOW AND/OR
RAIN/SNOW MIX BY TUESDAY NIGHT INTO WEDNESDAY. GUSTY WINDS OVER
30 MPH WILL ALSO ENVELOP A LARGE PORTION OF THE DAKOTAS AND
POTENTIALLY INTO MINNESOTA TUESDAY NIGHT INTO WEDNESDAY, AS
WELL. WINTER IMPACTS ARE EXPECTED IN PORTIONS OF OUR AREA,
ALTHOUGH THE SEVERITY AND LOCATION OF IMPACTS REMAINS IN
QUESTION. MORE DETAILS ON POTENTIAL IMPACTS AND UNCERTAINTY
REVOLVING AROUND THEM CAN BE FOUND BELOW.
COOLER, CONTINENTAL AIR MASS WRAPPING AROUND THE WESTERN AND
SOUTHERN FLANKS OF THE UPPER WAVE WILL USHER IN MORE AVERAGE
TEMPERATURES WITH HIGHS NEAR FREEZING AND LOW TEMPERATURES INTO
THE TEENS AND TWENTIES, POSSIBLY LOWER DEPENDING ON PENDING SNOW
COVER.
BY THURSDAY, MOST ENSEMBLE GUIDANCES MIGRATES THE NOW LARGE UPPER
LOW INTO THE GREAT LAKES REGION, WITH UPPER RIDGING OVER THE
NORTHERN PLAINS AND UPPER MIDWEST INTO THE WEEKEND. THE DEGREE
OF UPPER RIDGING REMAINS IN QUESTION, WITH LARGE VARIANCE IN
ENSEMBLE GUIDANCE. MORE SHALLOW UPPER RIDGING MAY ALLOW
OPPORTUNITY FOR PROGRESSIVE WAVES TO PASS THROUGH THE REGION
BRINGING PERIODS OF PRECIPITATION, INCLUDING ADDITIONAL WINTRY
PRECIPITATION, ALONG WITH INCREASED CHANCE FOR LARGER SWINGS IN
TEMPERATURE TRENDS ASSOCIATED WITH PROGRESSIVE WAVE PASSAGES
THROUGH THE REGION. A STRONGER UPPER RIDGE WOULD PROMOTE MORE
DRY CONDITIONS, WITH LESS CHANCE FOR LARGER SWINGS IN SHORT
DURATION TEMPERATURE TRENDS.
..WIDESPREAD RAINFALL MONDAY INTO TUESDAY
THERE IS HIGH CONFIDENCE IN RAINFALL FROM THE STRONG SOUTHERN
WAVE MOVING THROUGH OUR AREA LATE MONDAY INTO TUESDAY. THIS IS
PARTLY DUE TO HIGH CERTAINTY IN THE ANOMALOUS STRENGTH OF THE
UPPER WAVE MOVING INTO OUR AREA BEFORE INTERACTING WITH THE
EVENTUAL NORTHERN WAVE, AS WELL AS STRONG SIGNAL IN RICH
MOISTURE FEEDING INTO THE SOUTHERN WAVE. RAINFALL IS FORECAST TO
BE HEAVY AT TIMES. WHILE MOST AREAS WILL RECEIVE OVER A QUARTER
OF AN INCH OF RAINFALL, THERE IS AROUND A 50% CHANCE LOCATIONS
WITHIN THE RED RIVER VALLEY INTO MINNESOTA WILL RECEIVE BETWEEN
1 TO 2 INCHES OF RAINFALL. THIS MAY BRING MINOR IMPACTS,
ESPECIALLY TO THOSE WHO VENTURE INTO NON-PAVED AREAS,
THEREAFTER.
..POTENTIAL WINTER IMPACTS AND ASSOCIATED UNCERTAINTY
THE INTERACTION AND EVENTUAL MERGER OF THE AFOREMENTIONED TWO
UPPER WAVES BRINGS INHERENT UNCERTAINTY IN THEIR SYNOPTIC
EVOLUTION, PARTICULARLY WITHIN ENSEMBLE GUIDANCE 2 OR MORE DAYS
AHEAD OF TIME. THIS ALONE LOWERS PREDICTABILITY IN WINTER
IMPACTS PERHAPS MORE THAN USUAL. OTHER FACTORS CONTRIBUTING TO
UNCERTAINTY INCLUDE POTENTIAL FOR MESOSCALE SNOW BANDING VIA
FGEN EXTENDING OUT OF MB INTO NORTH-CENTRAL AND/OR NORTHEAST ND,
UNCERTAINTY IN AIR TEMPERATURES THAT INFLUENCE PRECIPITATION
TYPE, AND UNCERTAINTY IN SURFACE TEMPERATURES THAT INFLUENCE
ACCUMULATION POTENTIAL (OR LACK THEREOF VIA COMPACTION/MELTING).
OVERALL SUITE OF ENSEMBLE GUIDANCE CAN BE CAMPED INTO TWO
POTENTIAL SCENARIOS.
POTENTIAL SCENARIO 1: BOTH WAVES MERGE INTO A LARGE, STRONGER
WAVE THAT STALLS CLOSER TO OUR AREA. THIS WOULD RESULT IN
BETTER FORCING FOR ASCENT AND MORE MOISTURE WRAPPING AROUND THE
CIRCULATION RESULTING IN HIGHER SNOW AMOUNTS/RATES INTO PORTIONS
OF NORTH DAKOTA. HOWEVER, THIS SCENARIO MAY ALSO PROMOTE WARMER
AIR TEMPERATURES LINGERING LONGER WITHIN MINNESOTA LOCATIONS,
LIMITING COVERAGE OF MORE SUBSTANTIAL WINTER IMPACTS TO MORE
WITHIN NORTH DAKOTA. THIS SOLUTION CAN BE ILLUSTRATED BY THE 12Z
EURO DETERMINISTIC MODEL. THIS POTENTIAL SCENARIO ALSO MAY KEEP
MORE WIND ENERGY WITHIN THE DAKOTAS, BYPASSING MINNESOTA. THERE
IS STILL OVERLAP IN FALLING MODERATE SNOWFALL RATES WITH GUSTY
WINDS OVER 30 MPH TO DRIVE BLOWING SNOW IMPACTS IN ADDITION TO
POSSIBLE SNOW ACCUMULATIONS BETWEEN 3 AND 8 INCHES, HIGHEST
WITHIN EASTERN NORTH DAKOTA WEST OF THE RED RIVER VALLEY.
POTENTIAL SCENARIO 2: WAVE INTERACTIONS RESULT IN AN ELONGATED,
WEAKER WAVE THAT STALLS FURTHER AWAY FROM OUR AREA. THIS BRINGS
MORE DIFFUSE FORCING FOR ASCENT AND MOISTURE OVER THE DAKOTAS
INTO MINNESOTA, RESULTING IN LESS OVERALL SNOW TOTALS. HOWEVER,
THE DIFFUSE NATURE OF THIS SCENARIO WOULD ALLOW BETTER
OPPORTUNITY FOR GUSTIER WINDS TO SPREAD FURTHER EAST INTO
MINNESOTA IN ADDITION TO NORTH DAKOTA, AS WELL AS COLDER
TEMPERATURES TO ALLOW FOR LIGHT SNOW TO ENSUE. THIS WOULD RESULT
IN LESS SEVERE IMPACTS FROM LIGHT SNOW ACCUMULATIONS UNDER 3
INCHES AND LIMITED BLOWING SNOW POTENTIAL, BUT AT LEAST SOME
LIMITED WINTER IMPACTS PERHAPS OVER A LARGER SPATIAL AREA.
THERE IS AROUND A 20% CHANCE SEEING WINTER STORM CRITERIA
WITHIN PORTIONS OF EASTERN NORTH DAKOTA, PARTICULARLY NEAR THE
WESTERN DEVILS LAKE BASIN, AND WOULD NEED POTENTIAL SCENARIO 1
TO UNFOLD.
HIGH RESOLUTION GUIDANCE SHOULD JUST START TO ENVELOP THE
BEGINNING EVOLUTION OF WINTER IMPACTS STARTING TONIGHT INTO
MONDAY MORNING. IDEALLY, THIS WOULD HELP LESSEN
UNPREDICTABILITY, BUT GIVEN SYNOPTIC UNCERTAINTIES WITH UPPER
WAVE MERGER/INTERACTIONS, IT MAY TAKE LONGER.
AVIATION /06Z TAFS THROUGH 06Z TUESDAY/
ISSUED AT 1133 PM CST SUN NOV 17 2024
VFR CONDITIONS FOR ALL BUT THE TAIL END OF THE TAF PERIOD, AS WE
WILL SEE INCREASING CLOUDS BUT ANY MVFR CEILINGS AND PRECIP WILL
HOLD OFF UNTIL LATER TOMORROW EVENING. SOME GUIDANCE WAS
CALLING FOR VIS AT KFAR GOING DOWN TO 1 1/2SM DUE TO THE RAIN
BUT WASN'T CONFIDENT ENOUGH TO GO THAT LOW QUITE YET SO KEPT IT
IN THE 3-5SM RANGE. WINDS WILL SHIFT FROM A SOUTHERLY DIRECTION
TO MORE SOUTHEASTERLY TO EASTERLY, BUT WILL REMAIN BELOW 12 KTS
AT MOST SITES.
FGF WATCHES/WARNINGS/ADVISORIES
ND...NONE.
MN...NONE.
UPDATE...JR
DISCUSSION...CJ
AVIATION...JR
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