755
FXUS63 KABR 030917
AFDABR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ABERDEEN SD
317 AM CST MON FEB 3 2025
KEY MESSAGES
- LESS THAN AN INCH OF SNOW REMAINS POSSIBLE THROUGH THE FIRST
HALF OF TODAY MAINLY ALONG AND NORTH OF HWY 12.
- TEMPERATURES WILL TREND COLDER THROUGH THE REST OF THE WEEK,
WITH HIGHS DROPPING BACK DOWN INTO THE SINGLE DIGITS ABOVE 0F
TO LOWER 20S.
- A 30-60% CHANCE OF SNOW FOR WEDNESDAY AND WEDNESDAY NIGHT AND A
40-50% CHANCE OF SNOW FOR FRIDAY AFTERNOON THROUGH SATURDAY
AFTERNOON.
SHORT TERM /TODAY THROUGH TUESDAY AFTERNOON/
ISSUED AT 316 AM CST MON FEB 3 2025
AT 3 AM CST, A BROAD-BAND OF SNOW EXTENDED FROM NORTHERN SOUTH
DAKOTA UP INTO SOUTHERN NORTH DAKOTA. THERE HAVE BEEN SMALLER MORE
INTENSE BANDED-FEATURES SEEN AT TIMES WITHIN THIS BROADER SNOWBAND.
OFF THE RAP13 MODEL, THE FRONTOGENESIS FORCING BETWEEN 750HPA UP
600HPA HAS BEEN "STRONG" FOR SEVERAL HOURS NOW, AND WHILE THE OMEGA
PROG FOR LIFT HAS NOT BEEN OVERLY STRONG IN THIS EVENT, THE UPPER
LEVEL JET STREAM (LEFTOVERS FROM THE RECENT WEST COAST "ATMOSPHERIC
RIVER" EVENT) HAS BEEN MAINTAINING 120-150KNOT POCKETS OF JET STREAK
ENERGY FOR UPPER LEVEL LIFT-SUPPORT DURING THIS BANDED SNOW EVENT.
PERHAPS HELPING TO TIGHTEN UP SOME OF THE STRONGER EMBEDDED BANDED-
FEATURES THIS MORNING IS "COLD AIR INSTABILITY" (NEGATIVE EPV*)
SHOWN TO BE AVAILABLE IN THE RAP MODEL AND STEEP MID LEVEL LAPSE
RATES AS ADVERTISED IN RAP BUFKIT SOUNDINGS THE OVER THE PAST 48
HOURS AND IN THE MOST RECENT COUPLE OF KABR RAOBS. AREA SURFACE OBS
HAVE DROPPED IN VISIBILITY TO 1/2SM AT TIMES UNDER THESE SMALLER
MORE INTENSE EMBEDDED BANDS OF SNOW. SKIES ARE CLOUDY AND
TEMPERATURES RANGE FROM THE SINGLE DIGITS ABOVE 0F ACROSS NORTH
CENTRAL SOUTH DAKOTA TO THE MID/UPPER TEENS ACROSS THE
SOUTHERN/SOUTHEASTERN FORECAST ZONES. WINDS ARE OUT OF THE NORTH TO
NORTHEAST AROUND 10 TO 20 MPH WITH GUSTS UP TO 30 MPH.
THE HEAVIEST SNOWFALL WITHIN THIS BANDED SNOW EVENT IS HAPPENING
RIGHT NOW. THE 00Z RUN OF THE SNOWBAND TRACKER (SPT USING HREF)
PLACES SEVERAL MEMBERS ACROSS NORTHEAST SOUTH DAKOTA/WEST CENTRAL
MINNESOTA FROM NOW THROUGH 11Z BEFORE RELOCATING FURTHER EAST INTO
THE MN/WI AND THE GREAT LAKES REGION. QPF AND POPS GUIDANCE SUPPORTS
THE ONGOING FORECAST TRENDS THAT AFTER 12Z THIS MORNING, THIS BANDED
SNOW EVENT WILL BE WINDING DOWN, WITH PERHAPS A FEW TENTHS OF AN
INCH TO AN INCH OF SNOWFALL STILL POSSIBLE. NOT WANTING TO
CHANGE/TAKE DOWN THE WINTER WEATHER ADVISORY HEADLINE IN PLACE RIGHT
NOW, WITH THE MONDAY MORNING COMMUTE RAMPING UP IN THE NEXT FEW
HOURS. THE CURRENT WINDS ARE NOT EXPECTED TO INCREASE ALL THAT MUCH
TODAY. THE BLOWING SNOW MODEL GENERATED MAINLY PATCHY BLOWING SNOW
THIS MORNING. THERE WERE A COUPLE SPOTS WHERE "SCATTERED AREAS OF
BLOWING SNOW" SHOWED UP, ESPECIALLY ACROSS THE EASTERN SLOPES OF THE
PRAIRIE COTEAU/SISSETON HILLS REGION. MODEL PROGGED LOW LEVEL CAA
WILL CONTINUE, THOUGH, DROPPING FROM THE SINGLE DIGITS BELOW 0C THIS
MORNING TO APPX -17C TO -20C AT 12Z TUESDAY.
SURFACE HIGH PRESSURE WILL BE BUILDING DOWN ACROSS THE NORTHERN
PLAINS TODAY AND TONIGHT. BY MID-DAY TODAY, THE CWA SHOULD BE
BASICALLY VOID OF ANY PRECIPITATION. HOWEVER, AS THE NEXT ROUND OF
WAA-FORCED PRECIPITATION STARTS TO TAKE SHAPE ACROSS THE NORTHERN
HIGH PLAINS, A LITTLE BIT OF THE EASTERN-MOST EDGE OF THIS ZONE OF
FORCING MAY RESULT IN SOME LIGHT FALLING SNOW TICKLING THE WESTERN
EDGE (WEST RIVER ZONES) OF THE CWA FROM LATE THIS AFTERNOON THROUGH
TUESDAY MORNING. FOR THE MOST PART, THOUGH, IT LOOKS LIKE DRY
CONDITIONS SHOULD BE TAKING OVER DURING THE DAY TODAY AND PERSISTING
THROUGH TUESDAY. IT'S JUST GOING TO BE COLD! WIND CHILLS TONIGHT ARE
FORECAST TO DROP INTO A RANGE FROM APPX -10F ALONG THE I-90 CORRIDOR
TO AROUND -22F UP ALONG THE DAKOTAS BORDER COUNTIES. PRETTY COLD,
BUT NOT COLD ENOUGH TO SATISFY COLD WEATHER ADVISORY CRITERIA.
LONG TERM /TUESDAY EVENING THROUGH SUNDAY/
ISSUED AT 316 AM CST MON FEB 3 2025
TEMPERATURES 5-10 DEGREES BELOW NORMAL WILL BE IN PLACE THROUGH THE
MIDDLE OF THE WEEK THIS WEEK. WINDS THROUGHOUT THE PERIOD WILL
GENERALLY BE LIGHT ENOUGH SUCH THAT WIND CHILLS WILL BOTTOM OUT
AROUND -10 TO -15 DEGREES. THE ONE EXCEPTION TO THAT WILL BE
THURSDAY MORNING, WHEN GUSTS MAY REACH UPWARDS OF 30 KNOTS. WIND
CHILLS JUST BEFORE SUNRISE THURSDAY ARE FORECASTED TO GET AS LOW AS
-25 ACROSS PARTS OF NORTH CENTRAL SOUTH DAKOTA AND THE PRAIRIE
COTEAU WHERE WINDS ARE STRONGEST. WIND CHILL ADVISORY CRITERIA FOR
THOSE AREAS IS -30 DEGREES, AND LONG RANGE ENSEMBLE PROBABILITIES
GIVE A MAXIMUM OF 40% (WITH A BROADER 0-20% ACROSS THE NORTH) OF
REACHING THAT CRITERIA.
THERE WILL BE TWO CHANCES FOR PRECIPITATION THROUGH THE FORECAST
PERIOD. WEDNESDAY INTO THURSDAY WILL BE THE FIRST ROUND, CAUSED BY
THE EXIT REGION OF A SHORTWAVE TROUGH TO THE NORTHWEST. THE GREATEST
QPF POTENTIAL IS EXPECTED TO STAY TO THE NORTH IN CANADA AND NORTH
DAKOTA. THE PROBABILITY OF RECEIVING 1 INCH OF SNOW INCREASES FROM
SOUTHWEST TO NORTHEAST, FROM 10% IN THE PIERRE AREA UP TO 70% IN
PARTS OF NORTHEASTERN SOUTH DAKOTA AND WESTERN MINNESOTA. NO MORE
THAN 2 INCHES (40% IN NORTHEASTERN SOUTH DAKOTA) WOULD BE EXPECTED
WITH THIS SYSTEM.
THE SECOND CHANCE FOR SNOW WILL BE FRIDAY NIGHT INTO SATURDAY, WHERE
MODELS ARE SHOWING A MORE ROBUST SHORTWAVE TROUGH WILL PUT THE ABR
FORECAST AREA IN THE LEFT EXIT REGION AND UNDER A ~120KT JET STREAK
ALOFT. ENSEMBLE CLUSTERS SHOW A BIT OF A SLOWER PROGRESSION FOR THE
PATTERN, SO TIMING COULD EASILY BE PUSHED BACK IN FUTURE FORECAST
CYCLES. THERE IS STILL A LOT OF UNCERTAINTY IN SNOW VALUES, WITH AN
NBM PROBABILITY OF 1 INCH OF ~50% PAINTED ACROSS THE FORECAST AREA.
HOWEVER, THE 25TH-75TH SPREAD TELLS A BIT OF A DIFFERENT STORY:
PARTS OF CENTRAL AND NORTHEASTERN SOUTH DAKOTA HAVE A SPREAD OF 0-6
INCHES OF SNOW. THE UNCERTAINTY LIKELY COMES FROM THE SNOW RATIOS
PRODUCING WILDLY DIFFERENT OUTCOMES THROUGHOUT THE EVENT. FOR
EXAMPLE, COMPARING SOUNDINGS FROM THE EURO AND GFS ENSEMBLES AND IN
PARTICULAR THE 500-300MB LAYER (WHERE THE HIGHEST SHEAR AND UPWARD
MOTION WILL BE PRESENT) WE CAN FIND WHAT COULD POTENTIALLY BE THE
ROOT CAUSE OF THE ISSUE. IN THE EURO ENSEMBLE, TEMPERATURES IN THE
LAYER ARE MUCH COLDER IN THE GEFS, WHICH CREATES SATURATION ALOFT
(LEADING TO HIGHER SNOW RATIOS FORMING IN THE STRONGER OMEGA). THE
GEFS HAS MUCH WARMER TEMPERATURES ALOFT AND WILL LEAD TO LOWER
RATIOS FOR THE EVENT. BOTH OF THE PREVIOUSLY MENTIONED ENSEMBLES
PLACE THE 500-300MB LAYER UNDER A STRONG (100-120 KNOT) WARM AIR
ADVECTION REGIME, SO IT WOULD SEEM REASONABLE TO TRUST THE GEFS
OUTPUT OVER THE EURO AT THIS POINT IN TIME. LUCKILY, THERE IS STILL
A LONG TIME FOR THINGS TO BE SORTED OUT FURTHER BEFORE THE SYSTEM
APPROACHES.
AVIATION /06Z TAFS THROUGH 06Z MONDAY/
ISSUED AT 1116 PM CST SUN FEB 2 2025
TERMINALS KABR,KATY,KPIR,KMBG
SNOW IS TRENDING NORTHWARD WITH KMBG AND KABR THE MOST LIKELY TO
SEE MVFR/OCCASIONAL IFR VSBY IN SNOW. KATY AND KPIR WILL STILL BE
AFFECTED BY MVFR CIGS. ALL SITES ARE EXPECTED TO IMPROVE MONDAY
MORNING AS SNOW EXITS FROM WEST TO EAST.
ABR WATCHES/WARNINGS/ADVISORIES
SD...WINTER WEATHER ADVISORY UNTIL NOON CST TODAY FOR SDZ006>008-011.
WINTER WEATHER ADVISORY UNTIL 6 AM CST /5 AM MST/ EARLY THIS
MORNING FOR SDZ003>005-009-010.
MN...WINTER WEATHER ADVISORY UNTIL NOON CST TODAY FOR MNZ039-046.
SHORT TERM...DORN
LONG TERM...BC
AVIATION...WISE
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