637
FXUS63 KFGF 190946
AFDFGF
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND FORKS ND
346 AM CST THU DEC 19 2024
KEY MESSAGES
- A WINTER STORM WILL CONTINUE TO IMPACT THE REGION THROUGH THIS
AFTERNOON. ADDITIONAL SNOW ACCUMULATIONS ARE STILL EXPECTED
THIS MORNING. EVENT TOTAL SNOWFALL IS LIKELY TO RANGE FROM 2
TO 5 INCHES OVER THE LARGER REGION, WITH SMALLER AREAS OF
GREATER THAN 6 INCHES.
- WIDESPREAD BLIZZARD CONDITIONS ARE NOT EXPECTED (20% CHANCE),
WITH OCCASIONAL OR SCATTERED WHITEOUT CONDITIONS MOST LIKELY
TO OCCUR THIS AFTERNOON AS WINDS INCREASE.
- SEVERAL WEAKER FAST MOVING SYSTEMS MAY BRING LIGHT
ACCUMULATING SNOW FRIDAY NIGHT AND A WINTRY MIX SUNDAY NIGHT.
DISCUSSION
ISSUED AT 346 AM CST THU DEC 19 2024
..SYNOPSIS
CURRENT LARGE SCALE PATTERN FEATURES NORTHWEST FLOW, WITH THE
CURRENT STRONG CLIPPER MOVING THROUGH THE DAKOTAS INTO MINNESOTA.
LARGE SCALE FLOW EVENTUALLY BREAKS DOWN AS SHORTWAVE RIDGING BRINGS
MORE OF A SPLIT FLOW OR WESTERLY ZONAL FLOW INTO THE REGION LATE
THIS WEEKEND, FOLLOWED BY RISING HEIGHTS AS FLOW TRENDS MORE TO THE
SOUTHWEST, WHICH MAY FEATURE INCREASING CHANCES FOR PRECIPITATION
(WITH A SUBSET OF ENSEMBLES). THOSE SYSTEMS MAY ACTUALLY FAVOR LIQUID
PRECIPITATION (RAIN OR FREEZING RAIN). THERE ARE VARIANCES IN HOW THE
SMALLER DETAILS OF AND WAVES WITHIN THAT FLOW NEXT WEEK, AND NBM
CURRENTLY FEATURES VERY LOW CHANCES FOR MEASURABLE PRECIPITATION.
CONSENSUS IS STRONG ON A WARMING TREND, AND AFTER SEVERAL COLD DAYS
ABOVE AVERAGE TEMPERATURES ARE FAVORED HEADING INTO CHRISTMAS.
..WINTER STORM TODAY
THE MAIN MID LEVEL CIRCULATION ASSOCIATED WITH THE CURRENT CLIPPER-
TYPE SYSTEM IS JUST TO THE WEST, WITH THE AXIS OF STRONG 850MB WAA
IN PLACE THROUGH THE RED RIVER VALLEY. AN INITIAL SMALLER
CIRCULATION AND ENHANCED REGION OF FRONTOGENESIS DID DEVELOP A MORE
ORGANIZED BAND ALONG OUR WESTERN CWA, BUT THAT HAS SINCE
DISORGANIZED, WITH THE BROADER SNOW AREA TAKING ON THE TYPICAL
CHARACTERISTICS WE SEE WHEN WAA/SYNOPTIC ASCENT IS DOMINATING: BROAD
LIGHT TO MODERATE SNOW RATES WITH BRIEF "BURSTS" OF HEAVIER RATES
THAT ARE SHORTER LIVED AND TRANSIENT. THE CURRENT EVOLUTION
GENERALLY MATCHES WELL WITH THE 00Z HREF PMM FIELDS AND 1"/HR PROBS.
AS THE MAIN 700MB LOW SHIFTS INTO THE REGION 12-18Z SOME CAMS ARE
STILL SHOWING A NEW DEFORMATION ZONE BRIEFLY FORMING WITHIN THE
CENTRAL RED RIVER VALLEY AND NORTHWEST MN, THOUGH THERE ISN'T A
STRONG CONSENSUS (MORE GUIDANCE CONTINUES TO FAVOR A BROADER LIGHT
TO MODERATE SNOW REGION GRADUALLY WEAKENING AS IT EXITS IN THE
AFTERNOON).
GAUGING HOW MUCH SNOW HAS ALREADY FALLEN WITH LIMITED REPORTS SO
FAR, BUT WHERE REPORTS HAVE COME IN MOST LOCATIONS OUTSIDE OF THE
HEAVIER BANDING EARLIER ARE LIKELY SEEING RATES CLOSER TO 0.5"/HR.
BASED ON WEBCAMS AND FORECAST FOR ADDITIONAL TOTALS WE ARE LIKELY
STILL IN LINE FROM A BROAD REGION OF 2-5" (EVENT TOTAL) WITH MORE
LOCALIZED AREAS THAT ULTIMATELY RECEIVED 6"+ (WITHIN AREA OF
WARNING).
REGARDING BLOWING SNOW/WIND:
WHERE HEAVIER BUSTS OF SNOW ARE TRACKING VISIBILITIES ARE DROPPING TO
1/4 MILE OR LESS AT TIMES, BUT WINDS ARE GENERALLY IN THE 15-20 MPH
RANGE IN THOSE AREAS (SOUTHEAST-EAST). WINDS ARE STILL EXPECTED TO
INCREASE FROM THE NORTH THIS AFTERNOON WITH SUSTAINED WINDS 22-25KT
SUPPORTING OCCASIONAL/SCATTERED BLOWING SNOW (OF WHAT HAS FALLEN),
MAINLY IN THE RED RIVER VALLEY. THE SIGNAL FOR STRONGER WINDS IS
STILL TO THE WEST, AND 28KT+ SUSTAINED WOULD BE REQUIRED FOR
WIDESPREAD WHITEOUT (BLIZZARD) IMPACTS. PROBABILITIES FOR THAT ARE
STILL LOW. STILL, CONSIDERING THE BLOWING SNOW IMPACTS ALONG WITH
THE ACCUMULATING SNOW
REGARDING ONGOING WARNING/ADVISORIES:
SOME AREAS WILL SEE DECREASING
TRENDS IN SNOWFALL INTENSITY THIS MORNING (AS WE ARE ALREADY SEEING
IN DEVILS LAKE REGION), HOWEVER ADDITIONAL LIGHT ACCUMULATIONS ARE
STILL EXPECTED IN THOSE AREAS ALONG WITH BLOWING SNOW IMPACTS THIS
AFTERNOON. THE EVENT IS UNDERWAY AND MAIN PERIOD OF ACCUMULATION IS
ONGOING AND LASTING THROUGH NOON. WE ARE HOLDING OUR HAZARD PRODUCTS
AS IS AT THIS TIME, WITH THE EVENT UNDERWAY.
..LIGHT WINTRY PRECIPITATION FRIDAY NIGHT AND SUNDAY NIGHT
THERE IS A GENERAL CONSENSUS THAT SEVERAL PROGRESSIVE WAVES WILL PASS
INITIALLY THROUGH NORTHWEST FLOW FRIDAY NIGHT AND THROUGH WESTERLY
FLOW SUNDAY NIGHT. THE FRIDAY NIGHT WAVE CARRIES HIGHER
PREDICTABILITY AT THIS TIME WITH STRONGER AGREEMENT. THE WAVE IS
SHOWN TO BE MUCH WEAKER, BUT WITH BROAD SYNOPTIC ASCENT AND STILL
VERY COLD AIR IN PLACE IT IS THE TYPE OF SYSTEM COVERAGE MAY BE
HIGHER THAN REFLECTED IN NBM (HIGH COVERAGE/LOW QPF) WITH LIGHT
ACCUMULATIONS (SUB ADVISORY) FAVORED. THE WAVE SUNDAY NIGHT SHOWS
LESS AGREEMENT, BUT MAY INITIALLY BE WARMER AND SUPPORT A
BRIEF/LIGHT WINTRY MIX.
AVIATION /06Z TAFS THROUGH 06Z FRIDAY/
ISSUED AT 1025 PM CST WED DEC 18 2024
TAFS ARE GOING TO BE DIFFICULT TO PIN DOWN EXTENT OF IMPACTS
FROM THIS UPCOMING SYSTEM. AT THIS POINT, EXPECT AT LEAST MVFR
TO IFR CONDITIONS THROUGH AT LEAST 00Z DUE TO SN AND BLSN WITH
IMPACTS TO BOTH VISIBILITY AND CEILING. GIVEN THE LACK OF
WIDESPREAD OBSERVATIONS OF IFR CEILINGS AT THIS TIME, PREVAILING
CEILINGS HAVE BEEN NUDGED UPWARD TO 010. THIS IS NOT TO SAY IFR
CEILINGS WON'T BE OBSERVED, AS THERE ARE POCKETS OF IT OUT
THERE, IT IS JUST THAT CONFIDENCE IS LOW IN HOW WIDESPREAD AND
HOW LONG IFR CEILINGS WOULD LINGER OVER TAF SITES. EXPECT WINDS
TO INCREASE AND TO MOVE COUNTERCLOCKWISE THROUGH THE DAY UNTIL
THEY SETTLE ON JUST WEST OF DUE NORTHERLY TOMORROW AFTERNOON.
FGF WATCHES/WARNINGS/ADVISORIES
ND...WINTER STORM WARNING UNTIL 6 PM CST THIS EVENING FOR
NDZ006>008-014>016-024-026>030-038-039-049-053-054.
WINTER WEATHER ADVISORY UNTIL 6 PM CST THIS EVENING FOR NDZ052.
MN...WINTER STORM WARNING UNTIL 6 PM CST THIS EVENING FOR
MNZ001>003-014-015-022-027-029>032-040.
WINTER WEATHER ADVISORY UNTIL 6 PM CST THIS EVENING FOR
MNZ004>009-013-016-017-023-024-028.
DISCUSSION...DJR
AVIATION...PERROUX
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