609
FXUS63 KFSD 141105
AFDFSD
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SIOUX FALLS SD
605 AM CDT TUE OCT 14 2025
KEY MESSAGES
- RAIN WILL BECOME LIKELY ACROSS THE AREA TODAY, WITH EXPECTED
RAINFALL AMOUNTS THROUGH THE DAY INTO TONIGHT AVERAGING
AROUND 0.1" TO 0.4".
- CHANCES FOR RAIN REMAIN IN THE FORECAST FOR THE MIDDLE AND END
OF THE WEEK. THURSDAY EVENING WILL SEE THE HIGHEST CHANCES FOR
RAIN (30-60%), PRIMARILY FROM THE INTERSTATE 29 CORRIDOR AND
WESTWARD.
- AFTER A BRIEF RETURN TO NEAR TO BELOW NORMAL TEMPERATURES
TODAY, ABOVE NORMAL TEMPERATURES RETURN FOR THE MIDDLE AND
END OF THE WEEK.
DISCUSSION
ISSUED AT 335 AM CDT TUE OCT 14 2025
AN UNSETTLED PERIOD AHEAD FOR THE NEXT FEW DAYS AS AN UPPER LEVEL
TROUGH CURRENTLY DIGGING INTO THE PACIFIC COAST TRANSLATES EASTWARD
THROUGH FRIDAY. THIS PATTERN WILL KEEP OUR REGION IN A SOUTHWESTERLY
UPPER LEVEL FLOW, WITH A SERIES OF SHORTWAVES EJECTING NORTHWARD OUT
OF THE TROUGH - BRINGING OCCASIONAL RAIN CHANCES TO OUR AREA THROUGH
THE PERIOD.
CURRENTLY SEEING LIGHT SHOWERS PUSH OVER THE AREA EARLY THIS MORNING
- THIS IN RESPONSE TO MIDLEVEL ISENTROPIC LIFT OUT AHEAD OF A
SHORTWAVE TRACKING THROUGH EASTERN SD. MODEL SOUNDINGS INDICATE A
DEEP DRY LAYER BELOW 700 MB, SO MUCH OF THIS RAIN IS NOT REACHING
THE GROUND WITH ONLY TRACE AMOUNTS BEING RECORDED SO FAR. THIS IS
EXPECTED TO CHANGE BY LATER THIS MORNING AS LIFT INCREASES WITH A
MORE SIGNIFICANT UPPER LEVEL WAVE MOVING INTO THE AREA, COLLOCATED
WITH AN UPPER LEVEL JET STREAK ORIENTED OVER THE REGION. SOUNDINGS
AND RH TIME SECTIONS INDICATE DEEPER SATURATION OCCURRING FROM SOUTH
TO NORTH THROUGH THE DAY, WITH RAIN CHANCES BECOMING LIKELY DURING
THE PERIOD. RAINFALL TOTALS THROUGH THE DAY LOOK TO RUN AROUND 0.2"
TO 0.3" FOR MUCH OF THE AREA, THOUGH TAPERING LOWER TOWARD NORTHWEST
IA. WITH CLOUDS, SHOWERS, AND A COOL EASTERLY LOW LEVEL FLOW, IT
WILL FEEL LIKE A LATE FALL/EARLY WINTER DAY WITH HIGHS ONLY IN THE
UPPER 40S TO MID 50S.
BY TONIGHT THE AFOREMENTIONED SHORTWAVE AND UPPER LEVEL JET STREAK
MOVE OFF TO THE EAST, AND WITH DRYING MID LEVELS RAINFALL CHANCES
WILL BEGIN TO DIMINISH FROM WEST TO EAST. ADDITIONAL RAINFALL
AMOUNTS TONIGHT WILL RANGE FROM A FEW HUNDREDTHS OF AN INCH UP TO A
TENTH OF AN INCH. LOWS WILL DROP INTO THE 40S.
FORCING LOOKS WEAKER ON WEDNESDAY, THOUGH CANNOT RULE OUT A FEW
SCATTERED SHOWERS WITH PERSISTENT MID LEVEL WARM AIR ADVECTION. EVEN
SO, RAINFALL CHANCES WILL SIT IN THE LOWER RANGE (20-40%) WITH
AMOUNTS OF ONLY A COUPLE HUNDREDTHS EXPECTED. TEMPERATURES WILL
BEGIN TO WARM IN AN EVOLVING SOUTHERLY LOW LEVEL FLOW IN RESPONSE TO
DEEPENING SURFACE LOW PRESSURE OVER CO AND THE WESTERN PORTIONS OF
NE AND KS. WITH THAT, OUR HIGHS WILL CLIMB INTO THE 60S AND 70S.
ON THURSDAY, THE AFOREMENTIONED UPPER LEVEL TROUGH WILL SHIFT INTO
THE WESTERN HIGH PLAINS AS A SURFACE TROUGH DEVELOPS OVER WESTERN
SD. THIS WILL PUSH WARMER AIR INTO OUR AREA WITH HIGHS WELL INTO THE
70S - TOUCHING ON 80 IN OUR SOUTHERN ZONES. AT THIS POINT, ONLY LOW
RAIN CHANCES (20-30%) WILL RESIDE WEST OF INTERSTATE 29 DURING THE
DAY. THE SURFACE LOW PUSHES OFF TO THE NORTH AND EAST ON THURSDAY
NIGHT AND FRIDAY - PULLING A COLD FRONT THROUGH OUR AREA DURING THE
PERIOD. BOTH DETERMINISTIC MODELS AND ENSEMBLES INDICATE THE BEST
RAIN CHANCES (40-60%) OCCURRING WEST OF INTERSTATE 29 ON THURSDAY
EVENING AS THIS BOUNDARY PUSHES EASTWARD. NOT EXPECTING SEVERE
STORMS WITH THIS FEATURE DUE TO WEAK INSTABILITY, THOUGH A FEW
HUNDREDTHS J/KG OF CAPE MAY RESULT IN A FEW LIGHTNING STRIKES. ANY
RAIN POTENTIAL WOULD WANE BY FRIDAY AFTERNOON, WITH COOLER AIR
FEEDING IN BEHIND THE FRONT WITH HIGHS BACK INTO THE 60S TO LOWER
70S.
THE UPPER LEVEL TROUGH SHIFTS INTO THE EASTERN CONUS BY THE END OF
THE UPCOMING WEEKEND INTO THE BEGINNING OF NEXT WEEK. ALTHOUGH
TEMPERATURES LOOK TO FALL BACK TO NEAR SEASONAL AVERAGES FOR THE
WEEKEND, WE MAY CLIMB BACK TO ABOVE NORMAL TEMPERATURES BY NEXT WEEK
AS UPPER LEVEL RIDGING RETURNS ON THE BACKSIDE OF THE DEPARTING
TROUGH. MAINLY DRY WEATHER IS EXPECTED THROUGH THE PERIOD.
AVIATION /12Z TAFS THROUGH 12Z WEDNESDAY/
ISSUED AT 600 AM CDT TUE OCT 14 2025
DRY LOW LEVEL AIR HAS KEPT SCATTERED VERY LIGHT SHOWERS ACROSS
THE AREA DURING THE EARLY MORNING HOURS, THOUGH THIS ACTIVITY IS
EXPECTED TO PICK UP AND BECOME MORE WIDESPREAD BY MID MORNING
AS THE ATMOSPHERE CONTINUES TO SATURATE. BY AFTERNOON,
VISIBILITIES MAY FALL INTO THE MVFR RANGE IN HEAVIER SHOWERS AND
CEILINGS WILL LOWER INTO THE IFR RANGE. THE MID LEVELS WILL
BEGIN TO DRY OUT BY THIS EVENING, AND SHOWERS MAY DIMINISH TO
DRIZZLE BEFORE TAPERING OFF TONIGHT.
EASTERLY WINDS WILL INCREASE DURING THE MORNING, WITH GUSTS
AROUND 20 KTS INTO LATE THIS EVENING.
FSD WATCHES/WARNINGS/ADVISORIES
SD...NONE.
MN...NONE.
IA...NONE.
NE...NONE.
DISCUSSION...JM
AVIATION...JM
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