191
FXUS63 KABR 200530 AAC
AFDABR
AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE ABERDEEN SD
1130 PM CST TUE NOV 19 2024
KEY MESSAGES
- HIGH WIND WARNING WIND GUSTS OVER 58 MPH ARE EXPECTED ACROSS MUCH
OF CENTRAL AND NORTH CENTRAL SOUTH DAKOTA THROUGH WEDNESDAY
MORNING. ADVISORY STRENGTH SUSTAINED WINDS OF 30 MPH OR GREATER
AND GUSTS OVER 45 MPH ARE EXPECTED ELSEWHERE.
- ACCUMULATING SNOW LATE TONIGHT THROUGH WEDNESDAY EVENING WILL
MAINLY BE ACROSS NORTHEASTERN SOUTH DAKOTA AND WEST CENTRAL
MINNESOTA. THE CHANCE OF 2 INCHES OR MORE IS GREATER THAN 80
PERCENT FROM NORTHERN CLARK COUNTY THROUGH DAY AND MARSHALL
COUNTIES. THE CHANCE OF 6 INCHES OR MORE IS 60-70% OVER DAY AND
MARSHALL COUNTIES.
- STRONG WINDS COMBINED WITH FALLING SNOW WILL CREATE BLOWING SNOW
AND REDUCE VISIBILITIES OVER NORTHEASTERN SOUTH DAKOTA. HAZARDOUS
DRIVING CONDITIONS ARE EXPECTED FROM LATE TONIGHT THROUGH
WEDNESDAY EVENING AS A RESULT.
UPDATE
ISSUED AT 1124 PM CST TUE NOV 19 2024
SEE UPDATED AVIATION DISCUSSION BELOW.
UPDATE ISSUED AT 902 PM CST TUE NOV 19 2024
LIGHT SNOW HAS MOVED INTO PARTS OF THE CWA, THEREFORE HAVE
INCREASED POPS IN THOSE AREAS, MAINLY ACROSS PARTS OF THE NORTHERN
AND CENTRAL CWA. NO CHANGES MADE TO WINDS OR TEMPERATURES AT THIS
TIME.
SHORT TERM /THIS EVENING THROUGH WEDNESDAY NIGHT/
ISSUED AT 321 PM CST TUE NOV 19 2024
AT 3 PM CST, TEMPERATURES ARE COOLING INTO THE LOW TO MID 30S ACROSS
PORTIONS OF NORTH CENTRAL SOUTH DAKOTA. ELSEWHERE, TEMPERATURES ARE
STILL IN THE UPPER 30S TO THE LOW 40S. AT TIMES TODAY, THERE HAVE
BEEN POCKETS OF LIGHT RAIN OR LIGHT SNOW ACROSS PARTS OF NORTH
CENTRAL AND NORTHEAST SOUTH DAKOTA, WHERE IT HAS BEEN CLOUDY ALL
DAY. EARLIER, SKIES WERE CLEAR OUT ACROSS CENTRAL SOUTH DAKOTA. BUT
CLOUDS ARE BEGINNING TO FILL IN ACROSS THAT AREA.
THE TIGHT PRESSURE GRADIENT THAT HAS FORMED BETWEEN A NORTHERN
MINNESOTA 985HPA SURFACE LOW AND ~1028HPA SURFACE HIGH OUT OVER THE
ROCKIES NOW HAS THE FULL SUPPORT OF MODEST LOW LEVEL CAA ON 35 TO 50
KNOT MIXING LAYER WINDS AND THE SYNOPTIC-SCALE SUBSIDENCE REGION OF
THIS BROAD UPPER LOW OVER THE NORTHERN PLAINS TO BOLSTER THE
POTENTIAL FOR SUSTAINED WINDS TO RANGE FROM 35 TO 45 MPH AND WIND
GUSTS TO RUN UP TO BETWEEN 58 AND 65 MPH. HREF/NBM PROBABILITIES OF
GUSTS OVER 55 MPH ARE GREATER THAN 50% ACROSS PORTIONS OF CENTRAL
AND NORTH CENTRAL SOUTH DAKOTA FROM THIS AFTERNOON THROUGH LATE
WEDNESDAY MORNING. UPGRADED THE WIND ADVISORY ACROSS THE CWA WEST OF
THE JAMES RIVER VALLEY TO A HIGH WIND WARNING. BROWN/SPINK COUNTIES
EASTWARD TO THE MINNESOTA BORDER REMAIN IN AN ADVISORY AND THE
EXPIRATION TIMES (6PM CST WEDNESDAY) FOR THE WARNING AND ADVISORY
REMAIN THE SAME. THE PREVIOUSLY MENTIONED LOW LEVEL CAA WILL BE
ONGOING THROUGH WEDNESDAY MORNING, COOLING TEMPERATURES DOWN INTO
THE 20S.
IT IS LIKELY THAT THE HREF'S QPF/SNOWFALL OUTPUT IS OVER-DOING
THINGS OVER THE PRAIRIE COTEAU BETWEEN ~MIDNIGHT TONIGHT AND
MIDNIGHT WEDNESDAY NIGHT. AN UPSLOPE FAVORED WIND DIRECTION AND A
DEEP DGZ COLUMN WILL LIKELY BE IN PLAY LATE TONIGHT THROUGH
WEDNESDAY EVENING. HOWEVER, WHEN THE UPPER LOW ALONG THE NORTH
DAKOTA/MONTANA BORDER STARTS TO ELONGATE AND MEANDER EAST-SOUTHEAST
THROUGH THE REGION TONIGHT THROUGH WEDNESDAY NIGHT, THE AIRSTREAM
ALOFT IN WHICH FORCING/LIFT WILL BE MULLED-OVER, IS A TROWAL
AIRSTREAM. IN OTHER WORDS, NOT ANY REAL NOTICEABLE AREAS OF STRONG
LOW TO MID LEVEL FORCING OR LIFT TO SPEAK OF. JUST A PERIOD OF ABOUT
12 TO 18 HOURS OF WEAK FORCING/LIFT, PLUS THE PRAIRIE COTEAU'S
UPSLOPE COMPONENT. IT IS GENERALLY ACCEPTED THAT THE COTEAU WILL
EXPERIENCE ACCUMULATING SNOW LATER TONIGHT THROUGH WEDNESDAY NIGHT.
HOWEVER, NEARLY A FOOT OF SNOW (GUIDANCE) IN THIS TYPE OF SET-UP IS
TOO MUCH. WATERED DOWN THE QPF AND SNOW RATIOS (18-20:1 IS ALSO TOO
BULLISH) AND WAS ABLE TO GET THE SNOWFALL OUTPUT MORESO INTO A 3-
7INCH RANGE (AND THAT IS PROBABLY TOO HIGH, TOO). SO, BETWEEN THE
FALLING SNOW AND STRONG WINDS, AND WHAT ARE EXPECTED TO BE
TEMPERATURES COLD ENOUGH TO EFFICIENTLY BLOW SNOW AROUND, A WINTER
WEATHER ADVISORY HAS BEEN ISSUED FOR A PORTION OF THE PRAIRIE COTEAU
(SUBJECT TO FUTURE REVISIONS) STARTING AT MIDNIGHT TONIGHT AND
LASTING THROUGH LATE WEDNESDAY EVENING WHEN BOTH SNOWFALL AND WIND
SPEED SHOULD BE DECREASING SUFFICIENTLY TO NO LONGER WARRANT AN
ADVISORY.
PERUSING THE BLOWING SNOW SENSITIVITY TOOL, IF TEMPERATURES ARE IN
THE MID TO UPPER 20S, AND SNOW IS FALLING AT A RATE OF 1/4IN TO
1/2IN AN HOUR, SUSTAINED WIND SPEEDS WOULD HAVE TO BE 30MPH OR
HIGHER IN ORDER TO ACHIEVE VISIBILITIES (~44%-52%) LOW ENOUGH TO
WARRANT A WINTER WEATHER ADVISORY FOR ISOLATED TO SCATTERED
OCCASIONAL WHITE OUT CONDITIONS. IF THE TEMPERATURE IS OFF BY A FEW
DEGREES OR WIND SPEEDS ARE OFF BY A FEW MILES/HOUR, CONDITIONS
IMPROVE MARKEDLY OR DETERIORATE QUICKLY. THIS IS NOT A "SHUT THE
WORLD DOWN" SCENARIO, BUT A FEW INCHES OF SNOW ACCUMULATION WITH
SOME AREAS OF BLOWING SNOW/REDUCED VISBY SEEMS LIKE A GOOD CANDIDATE
FOR A WINTER WEATHER ADVISORY FOR SNOW AND BLOWING SNOW UP ON THE
COTEAU (AND PLUS IT'S THE FIRST WINTER EVENT OF THE SEASON).
LONG TERM /THURSDAY THROUGH TUESDAY/
ISSUED AT 321 PM CST TUE NOV 19 2024
OVERALL NEGLIGIBLE CHANCES FOR MOISTURE THURSDAY-FRIDAY WITH THE
UPPER LOW DEPARTURE INTO THE GREAT LAKES REGION REPLACED BY AN UPPER
RIDGE. ELONGATED SURFACE HIGH PRESSURE OVERHEAD SHIFTS EAST, SO WE
GO FROM LIGHT WINDS TO EASTERLY FLOW, AND THAT PUTS US IN A POOR
MIXING REGIME WITH A COLD AIRMASS IN PLACE. ALL THAT WE ARE GETTING
IN THE NBM IS A SLIGHT UPTICK IN TEMPERATURES FOR THE WEEKEND,
THOUGH THAT COMES WITH A GREATER RANGE IN THE 25TH/75TH PERCENTILES.
AS FOR PRECIPITATION, GENERALLY ITS A LOW CONFIDENCE/LOW QPF
FORECAST FOR THE WEEKEND, AS THE NEXT SURFACE LOW LIFTS NORTH OF OUR
AREA IN THE EC/GFS, WITH A WAVE THAT GETS DEFLECTED NORTH AS THE
UPPER RIDGE GETS JAMMED UP AGAINST THE PERSISTENT ALBEIT WEAKENED
EASTERN CONUS UPPER LOW. FOR US RIGHT NOW IT LOOKS MORE LIKE A COLD
FRONTAL PASSAGE WITH SNOW SHOWERS ON THE BACKSIDE FOR SUNDAY INTO
EARLY NEXT WEEK.
FOR NEXT WEEK, WHILE NBM KEEPS TEMPERATURES NEAR OR JUST BELOW
CLIMATOLOGY, DETERMINISTIC NBM IS A LITTLE HIGHER IN COMPARISON TO
THE NBM 50TH PERCENTILE LIKELY AS A RESULT OF THE PREVIOUS MONTHS
ABOVE NORMAL TEMPERATURES. BOTH A MAJORITY OF GEFS MEMBERS AND
DETERMINISTIC GFS SHOW ANOTHER, RATHER SIGNIFICANT COOLING TREND
ON/AFTER THE 24TH. THIS IS ALL UNDER A BAGGY TROUGH WITH MORE OR
LESS ZONAL FLOW OVERHEAD.
AVIATION /06Z TAFS THROUGH 06Z WEDNESDAY/
ISSUED AT 1124 PM CST TUE NOV 19 2024
TERMINALS KABR,KATY,KPIR,KMBG
VFR CIGS WILL REMAIN ACROSS SOUTH CENTRAL SOUTH DAKOTA OVERNIGHT
AND THROUGH THE DAY WEDNESDAY. ACROSS NORTH CENTRAL SOUTH DAKOTA,
MVFR CIGS WILL GIVE WAY TO VFR CONDITIONS BY MIDDAY WEDNESDAY.
CIGS WILL REMAIN AT MVFR LEVELS ACROSS THE EASTERN PART OF THE
AREA THROUGH THE TAF PERIOD. STRONG WEST TO NORTHWEST WINDS, WITH
GUSTS IN EXCESS OF 40 KNOTS WILL CONTINUE OVERNIGHT AND THROUGH
THE DAY WEDNESDAY, WITH SOME DIMINISHMENT WEDNESDAY EVENING. SNOW
WILL OCCUR ACROSS THE NORTHERN AND EASTERN PARTS OF THE REGION
OVERNIGHT, BRINGING PERIODS OF MVFR VSBYS DUE TO FALLING AND
BLOWING SNOW. THE SNOW WILL COME TO AN END ACROSS NORTH CENTRAL
SOUTH DAKOTA EARLY WEDNESDAY MORNING, BUT WILL CONTINUE ACROSS THE
EAST THROUGH THE DAY WEDNESDAY BEFORE COMING TO AN END EARLY
WEDNESDAY EVENING. THE HIGHEST AMOUNTS OF SNOW ARE EXPECTED
ACROSS THE SISSETON HILLS REGION OF FAR NORTHEASTERN SOUTH
DAKOTA.
ABR WATCHES/WARNINGS/ADVISORIES
SD...WINTER WEATHER ADVISORY UNTIL MIDNIGHT CST WEDNESDAY NIGHT FOR
SDZ007-008-011-019.
HIGH WIND WARNING UNTIL 6 PM CST /5 PM MST/ WEDNESDAY FOR
SDZ003>005-009-010-015>017-033>037-045-048-051.
WIND ADVISORY UNTIL 6 PM CST WEDNESDAY FOR SDZ006>008-011-
018>023.
MN...WINTER WEATHER ADVISORY UNTIL MIDNIGHT CST WEDNESDAY NIGHT FOR
MNZ039.
UPDATE...PARKIN
SHORT TERM...DORN
LONG TERM...CONNELLY
AVIATION...PARKIN
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