843
FXUS63 KABR 231728 AAC
AFDABR
AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE ABERDEEN SD
1228 PM CDT WED APR 23 2025
KEY MESSAGES
- RAINFALL CHANCES INCREASING THIS EVENING/TONIGHT THROUGH
THURSDAY. AMOUNTS GENERALLY FROM 0.25-0.75IN FROM HWY 14/HWY
212 AND POINTS SOUTH. LESSER AMOUNTS AROUND HWY 12 NORTHWARD.
- THE NEXT CHANCE OF RAIN (50 TO 80%) WILL BE FOR THE SECOND HALF
OF THE UPCOMING WEEKEND INTO EARLY NEXT WEEK. THERE IS A 15%
CHANCE FOR SEVERE STORMS EAST OF THE JAMES RIVER MONDAY.
UPDATE
ISSUED AT 1225 PM CDT WED APR 23 2025
SEE UPDATED AVIATION DISCUSSION BELOW.
UPDATE ISSUED AT 1009 AM CDT WED APR 23 2025
STILL SEEING JUST A FEW LIGHT RAIN SHOWERS ACROSS PARTS OF EAST
CENTRAL SOUTH DAKOTA THIS MORNING. MODELS STILL INDICATING ANOTHER
CHANCE FOR RAIN SHOWERS TO DEVELOP, MAINLY ALONG AND SOUTH OF
HIGHWAY 212, LATER THIS AFTERNOON. NO CHANGES MADE TO WINDS OR
TEMPERATURES AT THIS TIME.
SHORT TERM /TODAY THROUGH THURSDAY AFTERNOON/
ISSUED AT 356 AM CDT WED APR 23 2025
UPPER JET STREAK ON THE ORDER OF 80-90 KTS NOTED BY PREVIOUS SHIFT
CONTINUES TO GENERATE SPRINKLES/VERY LIGHT SHOWERS ACROSS THE
SOUTHERN CWA (I-90 CORRIDOR), WITH SOME ADDITIONAL DEVELOPMENT
FURTHER BACK TO THE WEST/NORTHWEST. IN FACT, HAD TO RECENTLY EXPAND
POPS BACK TO THE WEST/NORTHWEST AND CONTINUE A FEW HOURS LONGER INTO
THE MORNING AS THE WEAK LIFT ALOFT AND UPPER JET STREAK REMAIN IN
PLACE. ONLY EXPECTING A FEW HUNDREDTHS ANYWAY, SO NOTHING
SUBSTANTIAL, BUT DECIDED TO BRING IT UP ANYWAY.
COOLER AIR ALOFT ACROSS THE REGION TODAY WITH SURFACE HIGH PRESSURE
CENTERED JUST TO OUR NORTH. NORTHERLY BREEZES WILL BE FELT AND ASIDE
FROM ANY LINGERING MORNING SHOWERS ACROSS THE SOUTHERN CWA, THE
FIRST PART OF THE DAY LOOKS TO BE LARGELY DRY BEFORE MORE SHOWERS
MOVE INTO THE SOUTHERN CWA BY LATE AFTERNOON PERHAPS, BUT ESPECIALLY
INTO THE EVENING HOURS. AS A SURFACE BOUNDARY BECOMES BETTER
ESTABLISHED TO OUR SOUTH ACROSS THE CENTRAL PLAINS, WE GET INTO AN
OVERRUNNING PATTERN WITH SCATTERED/NUMEROUS SHOWERS MOVING NORTHWARD
INTO AND ACROSS THE REGION TONIGHT AND ESPECIALLY DURING THE DAY
THURSDAY. STILL, NOT SEEING ANYTHING IN THE WAY OF INSTABILITY THIS
FAR NORTH, SO MAINLY GENERIC LIGHT TO MODERATE SHOWERS AS ACTIVITY
INCREASES IN AREAL COVERAGE THIS EVENING/TONIGHT THROUGH THURSDAY.
IF ANYTHING, AREAS ACROSS THE FAR SOUTHERN CWA COULD GET A FEW
EMBEDDED RUMBLES OF THUNDER.
AS FOR PRECIPITATION AMOUNTS, MODELS SEEM TO GENERATE 0.25-0.75IN
FROM AREAS AROUND HWY 14/HWY 212 AND POINTS SOUTH. FURTHER NORTH
ALONG HWY 12 NORTHWARD TO THE SD/ND LINE, MODEL OUTPUT IS GENERALLY
CLOSER TO 0.15IN OR LESS. TOOK A LONGER LOOK AT 90TH PERCENTILE QPF
AS WELL TO GET A HANDLE ON SOME OF THE WETTER SCENARIOS POSSIBLE IF
BETTER COVERAGE OF MODERATE SHOWERS DEVELOPED AND PERSISTED FOR A
LONGER PERIOD OF TIME. SOME OF THESE VALUES SHOWN IN THE NBM/HREF
DATA IS CLOSER TO 0.75IN TO 1 INCH OR SLIGHTLY HIGHER. THE AREA
SHOWING UP FOR THIS IS AROUND THE HWY 14 REGION AND POINTS
SOUTHWARD. AGAIN, IT APPEARS THE NORTHERN CWA MAY HAVE A MUCH HIGHER
PROBABILITY OF BEING ON THE DRIER SIDE OF THIS RAINFALL EVENT
TONIGHT THROUGH THURSDAY AS UP HERE, 90TH PERCENTILE VALUES STRUGGLE
TO GET MUCH HIGHER THAN 0.25IN-0.50IN. ON THE OTHER HAND THOUGH,
IT'S INTERESTING TO NOTE THERE'S QUITE A BIT OF MODEL SPREAD (25TH-
75TH PERCENTILES) SHOWING UP ACROSS CENTRAL SD, INDICATIVE OF
REMAINING UNCERTAINTY IN AREAL COVERAGE OF PRECIPITATION AS SOME OF
THE DRIER END SCENARIOS (25TH PERCENTILES) ARE LESS THAN 0.25IN OVER
CENTRAL SD. MODEL SPREADS BETWEEN THE 25TH AND 75TH PERCENTILES
REMAIN AS HIGH AS 0.50IN OR HIGHER IN SOME INSTANCES OVER PARTS OF
CENTRAL SD.
LONG TERM /THURSDAY EVENING THROUGH TUESDAY/
ISSUED AT 356 AM CDT WED APR 23 2025
THE MAIN HIGHLIGHT IN THE LONG TERM WILL BE A STORM SYSTEM MOVING
ACROSS THE AREA SUNDAY THROUGH TUESDAY, BRINGING SOME MUCH NEEDED
RAINFALL, BUT ALSO A 15% CHANCE OF SEVERE WEATHER OVER THE EASTERN
HALF OF THE CWA ON MONDAY. CLUSTERS CONTINUE TO AGREE ON A LONGWAVE
TROUGH, WITH THE AXIS JUST OFF THE PACIFIC COAST, THURSDAY EVENING
INTO FRIDAY. THIS TROUGH MOVES ONSHORE SATURDAY, WITH THE CLUSTERS
STILL IN AGREEMENT ON THE AXIS FROM NORTH CENTRAL CA AND SOUTHWARD.
IT WILL CONTINUE TO TRACK EASTWARD AND BY MONDAY, MORE OF A SPLIT
TROUGH PATTERN FORMS OVER THE ROCKIES. THE NORTHERN MORE PROGRESSIVE
SHORTWAVE WILL THEN SHIFT NORTHEAST AND OVER THE NORTHERN PLAINS
MONDAY EVENING. THE SOUTHERN TROUGH IS A BIT SLOWER WITH ITS
PROGRESSION OVER THE CENTRAL AND SOUTHERN CONUS. OVERALL, THIS
LEAVES MUCH OF THE NORTHERN PLAINS IN SOUTHWEST FLOW ALOFT THROUGH
MONDAY EVENING WITH THE EASTERN HALF OF THE CWA IN THE LEFT EXIT
REGION OF A 30-50KT SOUTHWEST TO NORTHEAST ORIENTED JET STREAK, WITH
THE FAR EASTERN CWA IN THESE HIGHER WINDS. WINDS WILL DIMINISH AND
TURN NORTHWEST ON THE BACKSIDE OF THE SYSTEM TUESDAY-WEDNESDAY,
BRINGING IN DRIER AND A BIT COOLER AIR.
AT THE SURFACE, LINGERING RAIN SHOWERS (30-45%) WILL TAPER OFF
FRIDAY MORNING AS A HIGH PRESSURE SYSTEM MOVES IN OVER THE SOUTHERN
SASKATCHEWAN/MANITOBA BORDER BY 12Z AND CONTINUING TO TRACK
EAST/NORTHEAST OUT OF THE REGION THROUGH 12Z SATURDAY. THE LOW,
ASSOCIATED WITH THIS SHORTWAVE, WILL POSITION ITSELF OVER THE
NORTHERN ROCKIES EARLY SUNDAY. HOWEVER, GEFS/ENS HAVE A BIT OF A
DIFFERENCE IN THE POSITION WITH ENS BEING A BIT FURTHER NORTH (AND A
DEEPER LOW) OVER EASTERN MT AND GEFS MORE SOUTH OVER NORTHERN WY BY
12Z SUNDAY. BY 12Z MONDAY, MODELS STILL ARE QUIET DIFFERENT WITH THE
TRACK AS GEFS HAS THE CENTER OF THE LOW OVER ND (AND NOW DEEPER) AND
ENS MORE SOUTH OVER CENTRAL SD. THIS LOW WILL CONTINUE TO TRACK
EAST/NORTHEAST WITH THE CWA ON THE BACKSIDE OF THE LOW BY TUESDAY
MORNING/AFTERNOON. OF NOTE, GEFS'S TRACK STILL TRENDS FURTHER NORTH
AND NORTHEAST THAN ENS DURING THIS TIME, SO LOW CONFIDENCE ON EXACT
TRACK AS OF NOW.
THIS SYSTEM WILL BRING MUCH NEEDED RAIN TO THE AREA WITH POPS OF 50-
80%. HIGHEST POPS OF 65-80% ARE FORECASTED SUNDAY EVENING INTO EARLY
MONDAY AND AGAIN MONDAY EVENING INTO TUESDAY MORNING (50-65%) AS OF
NOW. PER RETURN FLOW, GFS IVT AND IWV STILL SHOWS A NORTHERN SURGE
OF MOISTURE/WV FROM THE GULF OVER THE REGION, AHEAD OF THE LOW
SUNDAY, WITH A MORE REINFORCED SURGE ON MONDAY. PER NAEFS, MEAN
SPECIFIC HUMIDITY WILL BE AN IMPRESSIVE 3 TO 3.5 STANDARD DEVIATION
ABOVE CLIMO SUNDAY AND MONDAY WITH PW VALUES 2 TO 2.5 STANDARD
DEVIATION ABOVE CLIMO, UP TO 1" OVER THE CWA! EC EFI FOR QPF HAS
VALUES BETWEEN 0.5-0.6 WITH A SHIFT OF TAILS OF ZERO ALONG THE ND/SD
BORDER SUNDAY NIGHT THROUGH MONDAY NIGHT. AS OF NOW, PROBABILITY OF
NBM 72HR QPF> 0.50", ENDING 12Z TUESDAY, IS 50-75%, HIGHEST OVER THE
JAMES RIVER VALLEY. PROB OF 1" IS 35-50% OVER THE EASTERN HALF OF
THE CWA, AGAIN HIGHEST OVER JAMES RIVER VALLEY. PRECIP WILL END WEST
TO EAST TUESDAY AFTERNOON INTO THE EVENING AS THE LOW CONTINUES TO
DEPART THE REGION.
DEWPOINTS FOR SUNDAY WILL RISE INTO THE 50S AND TEMPS WARMING INTO
THE INTO THE 70S (UPPER 70S OVER SOUTH CENTRAL SD). GEFS MUCAPE
VALUES LOOK TO RISE IN THE 1000-1700 J/KG RANGE WITH BULK SHEAR
BETWEEN 20-30KTS OVER CENTRAL SD. EC EFI FOR CAPE IS 0.6 TO 0.8,
HIGHEST WEST RIVER WITH A SOT OF 0 ALONG AND WEST OF THE MO RIVER.
CAPE/SHEAR IS LOWER AT 0.6 TO 0.7. PANGU/FENGWU MODELS ALONG WITH
CSU ML GUIDANCE HAS A 5-15% CHANCE FOR SEVERE WEATHER OVER THE CWA
AND UP TO 30% OVER SOUTH CENTRAL SD. SO THIS WILL BE SOMETHING TO
WATCH AS TIMING MAY NOT PLAY OUT WITH THE STRONGER WINDS/ASCENT
ARRIVING AFTER DIURNAL HEATING ALONG WITH GEFS INDICATING A CAP.
JUMPING AHEAD TO MONDAY AFTERNOON THINGS LOOK TO LINE UP BETTER. THE
EASTERN HALF OF THE CWA IS FORECASTED TO BE IN THE WARM SECTOR AND A
DRYLINE SETTING UP JUST AHEAD OF THE COLD FRONT WITH DEW POINTS TO
RANGE IN THE 50S ALONG AND EAST OF THE JAMES RIVER, AHEAD OF THE
DRYLINE. WAA WILL HELP INCREASE TEMPS INTO THE UPPER 70S FOR THIS
AREA AS EFI VALUES OF 0.7 TO 0.8 AND SOT OF ZERO JAMES RIVER VALLEY
AND EAST. SO WITH WARM MOIST AIR AT THE SURFACE, LIFT FROM THE
FRONT, AND STRONG DIVERGENCE ALOFT, PER JET STREAK, COULD SET THE
STAGE FOR SEVERE WEATHER OVER THE EASTERN CWA. INSTABILITY WILL
BUILD THROUGH THE DAY (ERODING THE MORNING CAP) AS EFI FOR CAPE IS
0.7 TO 0.8, HIGHEST OVER NORTHEASTERN SD WESTERN MN WITH A SOT OF
ZERO AND CAPE/SHEAR EFI OF 0.6 TO 0.7. ML GUIDANCE ONCE AGAIN HAS A
5 TO 15% CHANCE OF SEVERE WEATHER OVER THE EASTERN HALF OF SD AND UP
TO 30% OVER SOUTHEASTERN SD. SPC DOES CONTINUE TO HIGHLIGHT A 15%
RISK OF SEVERE WEATHER BUT NOW ONLY OVER THE FAR EASTERN HALF OF SD
INTO MN. BOTH SUNDAY AND MONDAY ARE STILL SEVERAL DAYS OUT AND EXACT
FORECAST IS SUBJECT TO CHANGE.
AVIATION /18Z TAFS THROUGH 18Z THURSDAY/
ISSUED AT 1225 PM CDT WED APR 23 2025
TERMINALS KABR,KATY,KPIR,KMBG
VFR CONDITIONS WILL PREVAIL ACROSS THE AREA THIS AFTERNOON AND
TONIGHT. MVFR CIGS WILL OVERSPREAD THE REGION THURSDAY MORNING.
SCATTERED RAIN SHOWERS ARE POSSIBLE ALONG AND SOUTH OF HIGHWAY 212
THIS EVENING INTO TONIGHT, THEN THE RAIN WILL BECOME MORE
WIDESPREAD AND PUSH NORTHWARD THURSDAY MORNING. PERIODS OF MVFR
VSBYS WILL BE POSSIBLE WITH THE RAIN.
ABR WATCHES/WARNINGS/ADVISORIES
SD...NONE.
MN...NONE.
UPDATE...PARKIN
SHORT TERM...TMT
LONG TERM...MMM
AVIATION...PARKIN
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