238
FXUS63 KFSD 162021
AFDFSD
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SIOUX FALLS SD
321 PM CDT WED APR 16 2025
KEY MESSAGES
- WARM, DRY, AND BREEZY CONDITIONS THIS AFTERNOON. ELEVATED TO
NEAR CRITICAL FIRE DANGER CONTINUES THROUGH EARLY THIS
EVENING. AREA AT HIGHEST RISK RESIDES EAST OF I-29.
- SHOWERS AND THUNDERSTORMS RETURN THURSDAY MORNING INTO FRIDAY
MORNING. SOME OF THESE STORMS MAY BECOME STRONG TO SEVERE. THE
BETTER CHANCE FOR STRONG TO SEVERE THUNDERSTORMS IS THURSDAY
AFTERNOON. AREA AT HIGHEST RISK FOR STRONG STORMS IS SOUTHEAST
OF A LINE FROM YANKTON SOUTH DAKOTA TO MARSHALL MINNESOTA.
- PERIODIC LOW PRECIPITATION CHANCES AND NEAR NORMAL
TEMPERATURES RETURN FOR THE WEEKEND INTO EARLY NEXT WEEK.
DISCUSSION
ISSUED AT 316 PM CDT WED APR 16 2025
THIS AFTERNOON-EVENING: WARM AND BREEZY WITH SOUTH-SOUTHEAST WINDS
THIS AFTERNOON. WINDS WILL DECREASE THROUGH THE LATE AFTERNOON TO
AROUND 10 MPH. TEMPERATURES IN THE MID TO UPPER 70S WILL COOL DOWN
TO LOWS IN THE 40S AND 50S. CONDITIONS THIS AFTERNOON ARE NEAR
CRITICAL FOR FIRE DANGER. HOWEVER, SOUTHERLY WINDS ARE TRANSPORTING
MOISTURE NORTHWARD. AS DEW POINTS INCREASE, WINDS ARE EXPECTED TO
DECREASE. THE WORST CONDITIONS ARE EXPECTED EAST OF I-29, WHERE
OCCASIONAL GUSTS OF 25-30 MPH MAY CREATE TEMPORARY PERIODS OF
CRITICAL FIRE CONDITIONS. PLEASE CONTINUE TO USE CAUTION WITH
SOURCES OF SPARKS.
THURSDAY: EARLY THURSDAY MORNING A MIDLEVEL SHORTWAVE AND A BAND OF
POSITIVE VORTICITY ADVECTION WILL MOVE THROUGH THE AREA BRINGING LOW
CHANCES (<30%) FOR MORNING PRECIPITATION. AS MENTIONED IN PREVIOUS
DISCUSSIONS, THE ATMOSPHERE WILL BE STRONGLY CAPPED. THE MOST LIKELY
STORM INITIATION WILL BE ELEVATED ALONG THE 700 MB FRONT. HERE THERE
RESIDES BETWEEN 500-1000 J/KG MUCAPE SUFFICIENT TO SUPPORT THE
DEVELOPMENT OF ISOLATED TO SCATTERED SHOWERS AND THUNDERSTORMS. AS
THE NOSE OF THE LLJ PUSHES BRIEFLY INTO THE AREA, AN INCREASE IN
SHEAR TO AROUND 35 KTS, AND STEEP MIDLEVEL LAPSE RATES OF 7.5-8 DEG
C/KM COULD SUPPORT FORMATION OF HAIL UP TO AROUND AN INCH.
AS THE SURFACE LOW AND COLD FRONT MOVE THROUGH THE REGION THURSDAY
AFTERNOON ANOTHER ROUND OF SHOWERS AND THUNDERSTORMS IS POSSIBLE.
HIGHS WILL DEPEND ON TIMING OF THE FRONTAL PASSAGE, BUT IN GENERAL
HIGHS SHOULD BE IN THE 60S WEST OF THE JAMES RIVER VALLEY, AND THE
70S TO THE EAST. LOWS WILL FALL TO THE 30S AND 40S.
FOR THURSDAY AFTERNOON MODEL SOUNDINGS CONTINUE TO SHOW A WELL
CAPPED ENVIRONMENT. HOWEVER, IF WE MANAGE TO BREAK THE CAP, THERE IS
1000-1500 J/KG OF MUCAPE AVAILABLE. BULK SHEAR INCREASES TO 40-50
KTS WITH LAPSE RATES OF 7-7.5 DEG C/KM. IF WE BREAK THE CAP, STORMS
MAY QUICKLY BECOME STRONG TO SEVERE THURSDAY AFTERNOON. HAIL OF 1 TO
1.25 INCHES IS POSSIBLE, AS WELL AS WIND GUSTS OF 60 MPH. COVERAGE
OF STRONGER THUNDERSTORMS LOOKS TO BE SOUTHEAST OF A LINE FROM
YANKTON, SOUTH DAKOTA TO MARSHALL, MINNESOTA. CAMS DO NOT AGREE WELL
ON THE TIMING OR LOCATION OF STORM INITIATION, BUT THE MOST LIKELY
TIMING WILL BE BETWEEN 4 AND 10 PM THURSDAY AFTERNOON/EVENING.
FRIDAY - EARLY NEXT WEEK: SHOWERS LINGER THROUGH FRIDAY MORNING,
BEFORE DRYING OUT FRIDAY AFTERNOON. WINDS WILL BE NORTHERLY AND
BREEZY, GUSTING 30-35 MPH. HIGHS WILL BE COOL IN THE UPPER 40S TO
MID 50S.
A LARGE MID TO UPPER TROUGH MOVES EAST THROUGH THE REGION THIS
WEEKEND. BY SUNDAY THE ASSOCIATED SURFACE LOW IS EXPECTED TO MOVE TO
THE SOUTHEAST OF OUR REGION. THERE REMAINS HIGH UNCERTAINTY IN TRACK
OF THE LOW, WHICH WILL IMPACT OUR CHANCES FOR PRECIPITATION SUNDAY
AFTERNOON. AS WE HEAD INTO NEXT WEEK, A SERIES OF WAVES THROUGH
MOSTLY MERIDIONAL FLOW WILL KEEP PERIODIC CHANCES FOR
PRECIPITATION IN THE FORECAST.
AVIATION /18Z TAFS THROUGH 18Z THURSDAY/
ISSUED AT 1237 PM CDT WED APR 16 2025
MOSTLY CLEAR SKIES FOR THE FIRST HALF OF THE PERIOD, WITH CLOUDS
INCREASING AFTER 17.09Z AS A WAVE APPROACHES FROM THE WEST. WINDS
WILL BE SOUTHEASTERLY BETWEEN 10-15 KTS, WITH GUSTS UP 20 KTS. THE
STRONGEST WINDS ALONG AND EAST OF I-29, WHERE WINDS OF 15-20 KTS ARE
EXPECTED WITH GUSTS UP TO 25 KTS. WINDS BEGIN TO SHIFT AS THE
AFOREMENTIONED WAVE APPROACHES, GRADUALLY BECOMING NORTHERLY FROM
WEST TO EAST THROUGH THE MORNING AND AFTERNOON. BEHIND THE WAVE
WINDS WILL INCREASE AFTER THE END OF THE PERIOD, TO 25-30 KTS GUSTS.
A BRIEF PERIOD OF LLWS IS POSSIBLE AT KSUX THURSDAY EARLY MORNING,
HOWEVER CONFIDENCE IS TOO LOW TO INCLUDE IN THE TAF CYCLE.
CEILINGS WILL DECREASE WITH THE INCREASING CLOUDS, BUT LOOK TO
REMAIN IN THE VFR TO LOW VFR CATEGORY. AREAS EAST OF THE SOUTH
DAKOTA/MINNESOTA/IOWA BORDER COULD SEE CEILINGS DOWN TO MVFR FOR A
BRIEF PERIOD THURSDAY MORNING. ISOLATED TO SCATTERED SHOWERS AND
THUNDERSTORMS ARE POSSIBLE THURSDAY MORNING THROUGH ABOUT NOON. A
SECOND ROUND OF POSSIBLY STRONGER SHOWERS AND THUNDERSTORMS ARE
EXPECTED FOR THURSDAY AFTERNOON AND EVENING, THOUGH THERE REMAINS
SOME UNCERTAINTY DUE TO FRONTAL PASSAGE TIMING.
FSD WATCHES/WARNINGS/ADVISORIES
SD...NONE.
MN...NONE.
IA...NONE.
NE...NONE.
DISCUSSION...AJP
AVIATION...AJP
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