386
FXUS63 KABR 251130 AAA
AFDABR
AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE ABERDEEN SD
530 AM CST WED DEC 25 2024
KEY MESSAGES
- FOGGY CONDITIONS WILL CONTINUE THIS MORNING, ESPECIALLY FROM THE
JAMES VALLEY EAST. VISIBILITY OF HALF A MILE OR LESS WILL BE
POSSIBLE IN SOME AREAS. FOG IS EXPECTED TO REDEVELOP AGAIN TONIGHT
INTO THURSDAY MORNING.
- THERE IS UP TO A 35% CHANCE OF LIGHT RAIN FORECAST FRIDAY INTO
EARLY SATURDAY OVER PARTS OF NORTHEASTERN SD AND WESTERN MN.
- TEMPERATURES WILL RUN AROUND 10 TO 20 DEGREES ABOVE NORMAL FROM
THURSDAY THROUGH SUNDAY.
SHORT TERM /TODAY THROUGH WEDNESDAY/
ISSUED AT 149 AM CST WED DEC 25 2024
NOT MUCH CHANGE IN THE THINKING FOR THE SHORT TERM FORECAST. MAIN
CONCERN WILL BE FOG/LOW STRATUS THROUGH THURSDAY. CONFIDENCE IS LOW
ON SPECIFICS OF LOCATION AND INTENSITY.
UPPER RIDGING BUILDS OVER THE REGION TODAY. AHEAD OF A WEAK SFC
FRONT, SOUTHERLY WINDS GUSTING 25 TO 35 MPH THIS AFTERNOON WILL HELP
USHER IN SOME WARMER, ABOVE NORMAL HIGH TEMPERATURES. HOWEVER, ONCE
AGAIN, THERE WILL BE SOME MODERATION ACROSS THE EAST FROM PERSISTENT
LOW STRATUS. THE BIG QUESTION IS WHEN THE STRATUS EXITS. AN UPPER
TROUGH AND SFC FRONT/TROUGH STALL OUT AROUND CENTRAL SD BY THIS
EVENING. THERE WILL STILL BE DECENT LLM ON SOUTHERLY FLOW ACROSS THE
EAST TONIGHT, THOUGH THERE'S A SHIFT MORE TO A DRIER SOUTHWEST
DIRECTION. HI-RES MODELS DEVELOP MORE FOG ACROSS THE EAST AND
BETWEEN THE MISSOURI AND JAMES VALLEYS TONIGHT BUT DIFFER ON
LOCATION, INTENSITY AND LONGEVITY. DUE SOUTH SFC FLOW LOCKS BACK IN
ON THURSDAY AHEAD OF A SFC LOW IN WESTERN SD WHICH KEEPS THE
POTENTIAL FOR SOME FOG/STRATUS IN THE FORECAST.
WITH MOST LOCATIONS ABOVE QUARTER MILE VSBY EVEN NOW, THE DENSE FOG
ADVISORY MAY BE ABLE TO GO AROUND SUNRISE. WILL CONTINUE TO MONITOR
AND EVALUATE, BUT COULD SEE LETTING CENTRAL SD COUNTIES GO EARLY.
LONG TERM /THURSDAY THROUGH MONDAY/
ISSUED AT 149 AM CST WED DEC 25 2024
MODEL SOUNDINGS SHOW THE PERSISTENCE OF LOW-LEVEL MOISTURE THROUGH
EARLY SATURDAY MORNING ACROSS NORTHEASTERN SOUTH DAKOTA AND WESTERN
MINNESOTA, LIKELY CONTINUING THE LAYER OF FOG THROUGH THAT TIME
PERIOD. NBM PROBABILITIES OF LESS THAN 5 MILES OF VISIBILITY PEAKS
AROUND 30% FOR THE FRIDAY AND SATURDAY TIME PERIOD. THIS MAY SEEM
RELATIVELY LOW BUT AT THE EQUIVALENT TIME RANGE FOR THE CURRENT FOG
LAYER DOWN TO QUARTER MILE VISIBILITIES, NBM GAVE 10-20% CHANCES.
THEREFORE GIVEN THE PROFILE, PROBABILITIES, AND THE LACK OF STRONG
SYNOPTIC SCALE FORCING OVER THE NEXT FEW DAYS, THERE IS AN INCREASED
LEVEL OF CONFIDENCE IN THE FOG/LOW CLOUD LAYER STICKING AROUND
THROUGH EARLY MORNING SATURDAY. MODEL TEMPERATURES FRIDAY AND
SATURDAY ARE 10-15 DEGREES ABOVE NORMAL, BUT GIVEN THE CLOUD COVER
THAT WARMUP MAY BE HARDER TO COME BY.
EARLY SATURDAY MORNING IS WHEN AN UPPER LEVEL TROUGH WILL PUT THE
AREAS JUST EAST OF THE ABR FORECAST AREA INTO THE LEFT EXIT REGION
OF THE JET STREAK. EASTERN SOUTH DAKOTA AND WESTERN MINNESOTA COULD
SEE SOME PRECIPITATION OUT OF THIS, WITH A FAIRLY SHARP GRADIENT OF
10% IN THE JAMES RIVER VALLEY TO 35% AT THE SD/MN BORDER. ONLY A
COUPLE HUNDREDTHS OF PRECIPITATION, LIKELY FALLING AS RAIN, IS
CURRENTLY FORECASTED. HOWEVER, A SLIGHT WESTERLY TREND IN THE TRACK
OF THE LOW COULD SEE THOSE NUMBERS START TO INCREASE RATHER QUICKLY.
NEXT POTENTIAL IMPACTS COME ON MONDAY, WHERE SHORTWAVE INDUCED
PRECIPITATION ON THE NORTH SIDE OF A SURFACE LOW PRESSURE WILL
IMPACT AT LEAST PART OF THE FORECAST AREA. PRECIPITATION WILL LIKELY
FALL AS SNOW DUE TO SUFFICIENT MOISTURE ALOFT AND TEMPERATURES NEAR
OR JUST ABOVE FREEZING FORECAST. CURRENT PROBABILITIES OF RECEIVING
1" OF SNOW IS ABOUT 40% AT THE HIGHEST OVER CENTRAL SOUTH DAKOTA,
BUT THAT VALUE JUMPS UP TO 60% OVER PARTS OF SOUTH CENTRAL SOUTH
DAKOTA. THE SAME CAN BE SAID ABOUT 2" OF SNOW, JUMPING FROM 20%
WITHIN THE FORECAST AREA TO 40% JUST SOUTH OF THE FORECAST AREA.
ONCE AGAIN, WE CAN SEE THAT A SLIGHT SHIFT IN THE TRACK OF THE LOW
WILL MAKE A HUGE DIFFERENCE WITH THIS SYSTEM.
AVIATION /12Z TAFS THROUGH 12Z THURSDAY/
ISSUED AT 528 AM CST WED DEC 25 2024
TERMINALS KABR,KATY,KPIR,KMBG
LOW STRATUS AND FOG PERSIST ACROSS THE EAST THIS MORNING WITH IFR
CIGS AND VSBY. EXPECT KATY TO REMAIN IFR, BUT COULD SEE
IMPROVEMENT TO MVFR AT KABR BY EARLY THURSDAY MORNING. HAVE KPIR
AND KMBG REMAINING VFR THROUGH THE PERIOD, BUT CAN'T COMPLETELY
RULE OUT SOME FOG REDEVELOPMENT TOWARD MORNING THURSDAY.
ABR WATCHES/WARNINGS/ADVISORIES
SD...DENSE FOG ADVISORY UNTIL NOON CST TODAY FOR SDZ004>011-016>023-
034>037-051.
MN...NONE.
SHORT TERM...WISE
LONG TERM...BC
AVIATION...WISE
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