149
FXUS63 KFSD 192329
AFDFSD
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SIOUX FALLS SD
629 PM CDT MON OCT 19 2026
KEY MESSAGES
- TEMPERATURES THIS WEEK ARE EXPECTED TO BE WARM FOR THIS TIME
OF YEAR, IN THE UPPER 60S AND 70S. AVERAGE HIGHS FOR THIS
TIME OF YEAR ARE UPPER 50S TO LOW 60S, WITH LOWS IN THE MID TO
UPPER 30S.
- DRY CONDITIONS ARE EXPECTED THROUGH THURSDAY EVENING OF THIS
WEEK. RAIN CHANCES RETURN FRIDAY MORNING AND CONTINUE THROUGH
THE WEEKEND. (ROUGHLY 50%)
- WARM, DRY, AND PERIODICALLY BREEZY CONDITIONS THIS WEEK WILL
LEAD TO LOCALIZED ELEVATED FIRE DANGER.
DISCUSSION
ISSUED AT 200 PM CDT MON OCT 19 2026
A FEW HIGH CIRRUS CLOUDS AND LIGHT SOUTHEAST WINDS WILL RESULT IN A
VERY PLEASANT FALL EVENING. WEAK WAA OVERNIGHT WILL KEEP OUR LOWS
WARM FOR THIS TIME OF YEAR, IN THE LOW TO MID 40S. (AVERAGE IS MID
30S) EARLY TUESDAY MORNING SOME PATCHY VALLEY FOG IS POSSIBLE,
ESPECIALLY FOR AREAS ALONG AND WEST OF THE JAMES RIVER VALLEY. HERE
ENSEMBLES INDICATE A ROUGHLY 20-40% PROBABILITY OF VISIBILITY
FALLING TO 2 MILES OR LESS. ANY FOG THAT FORMS WILL BE SHORT LIVED
AND WILL MIX OUT QUICKLY AS WINDS BEGIN TO INCREASE AFTER SUNRISE.
TUESDAY AN UPPER RIDGE BROADENS AND SHIFTS EAST OVER CENTRAL AND
EASTERN CONUS. SURFACE HIGH PRESSURE SETTLES OVER THE GREAT LAKES
REGION, AND WINDS WILL BECOME SOUTHERLY. AT THE SAME TIME A MID-
LEVEL WAVE ALONG THE WESTERN US/CAN BORDER WILL PUSH SOUTHEAST. AS
IT DOES SO THE SPG AT THE SURFACE WILL TIGHTEN AND WINDS WILL
INCREASE AND BECOME BREEZY. BY MID-TUESDAY AFTERNOON GUSTS OF 15-25
MPH ARE EXPECTED WITH THE HIGHEST WINDS ALONG AND WEST OF THE JAMES
RIVER VALLEY. OCCASIONAL GUSTS UP TO 30 MPH ARE POSSIBLE IN
SOUTH CENTRAL SOUTH DAKOTA. THE NBM CONTINUES TO HAVE A LOW BIAS
WHERE HIGH TEMPERATURES ARE CONCERNED. AFTER COORDINATION WITH
NEIGHBORS, BOOSTED HIGHS WITH A BLEND OF NBM/NBM90. HIGHS FOR
TUESDAY ARE EXPECTED TO CLIMB INTO THE UPPER 60S TO LOW 70S,
WITH AVERAGES FOR THIS TIME OF YEAR IN THE UPPER 50S TO LOW 60S.
WHILE MINIMUM RELATIVE HUMIDITY VALUES WILL REMAIN WELL ABOVE
CRITICAL (NEAR 40% OR GREATER) THE WARM AND DRY CONDITIONS WILL
RESULT IN THE GRASSLAND FIRE DANGER INDEX ELEVATING TO THE MODERATE
CATEGORY FOR AREAS ALONG AND WEST OF I-29 TUESDAY. THE MAIN CONCERN
FOR FIRE WILL BE IN THE FIELDS THEMSELVES AS HARVESTING OPERATIONS
CONTINUE. WARM, DRY, AND PERIODICALLY BREEZY CONDITIONS ARE EXPECTED
TO CONTINUE THROUGH THE WEEK, KEEPING FIRE DANGER SLIGHTLY ELEVATED.
PLEASE USE CAUTION AND REPORT ANY FIRES IMMEDIATELY.
EARLY WEDNESDAY MORNING THE PREVIOUSLY MENTIONED WAVE WILL DRAG A
WEAK COLD FRONT THROUGH THE REGION. GUIDANCE HAS CONTINUED TO BACK
OFF ON RAIN CHANCES WITH THE FRONT, KEEPING ANY RAIN THAT FORMS WELL
SOUTH OF OUR CWA. WINDS WILL CHANGE FROM SOUTHERLY TO SOUTHEASTERLY
AS THE FRONT MOVES THROUGH IN THE AFTERNOON. HIGHS FOR WEDNESDAY
WILL AGAIN BE WELL ABOVE AVERAGE IN THE LOW TO MID 70S.
THROUGH THE OVERNIGHT AND CONTINUING ON INTO FRIDAY STRONG WAA IN
THE MID LEVELS WILL WORK TO SHARPLY AMPLIFY THE UPPER RIDGE. HEIGHTS
ALOFT WILL RISE TO NEAR THE MAXIMUM OF CLIMATOLOGY. AT THE SURFACE
WE CAN EXPECT CLEAR SKIES AND WARM HIGHS IN THE MID TO UPPER 70S
BOTH THURSDAY AND FRIDAY. WINDS WILL ALSO BE INCREASING BEGINNING
THURSDAY AFTERNOON AS A DEEPENING UPPER TROUGH OFF THE WESTERN COAST
MOVES INLAND. THE TIGHTENING SPG WILL RESULT IN AFTERNOON WIND GUSTS
OUT OF THE SOUTH-SOUTHEAST AT 15 TO 25 MPH. STRONGEST WINDS WILL BE
ALONG AND WEST OF I-29, WITH OCCASIONAL GUSTS TO 30 MPH
POSSIBLE OVER CENTRAL SOUTH DAKOTA. GUSTY WINDS MOVE SLOWLY EAST
THROUGH THE OVERNIGHT AND INTO FRIDAY. BY NOON WIDESPREAD GUSTS
OF 25 TO 35 MPH ARE POSSIBLE. ONCE AGAIN THE STRONGEST WINDS
WILL BE LOCATED OVER CENTRAL SOUTH DAKOTA WHERE GUSTS IN EXCESS
OF 45 MPH ARE POSSIBLE. WINDS DECREASE GRADUALLY THROUGH THE
OVERNIGHT, BUT CONTINUE GUSTING 20-30 MPH THROUGH EARLY SATURDAY
AFTERNOON.
BY EARLY FRIDAY MORNING THE FIRST WAVE OF VORTICITY MOVES INTO THE
REGION BRINGING CHANCES FOR SHOWERS AND POSSIBLY A FEW STRIKES OF
LIGHTNING. BY FRIDAY EVENING THE MAIN SURFACE COLD FRONT WILL BE
LOCATED OVER CENTRAL SOUTH DAKOTA, AND RAIN CHANCES INCREASE AND
MOVE EAST WITH THE IT. AT THIS POINT MODEL DIVERGENCE IS LARGE, AND
TOO UNCERTAIN TO TRY TO DESCRIBE TRACK AND TIMING. RAIN TOTALS ARE
ALSO VERY UNCERTAIN WITH ENSEMBLES CURRENTLY SHOWING A 50%
PROBABILITY OR LESS OF 0.25 INCHES. SEVERE WEATHER DURING THIS TIME
IS NOT ANTICIPATED.
AVIATION /00Z TAFS THROUGH 00Z WEDNESDAY/
ISSUED AT 627 PM CDT MON OCT 19 2026
VFR THROUGH THE PERIOD. PATCHY LOW LAND FOG WILL BE POSSIBLE
LATER TONIGHT AND EARLY TUESDAY MORNING. SOUTHERLY WINDS WILL
INCREASE ON TUESDAY MORNING, WITH GUSTS OF 25 TO 30 MPH IN THE
AFTERNOON, STRONGEST WEST OF I-29.
FSD WATCHES/WARNINGS/ADVISORIES
SD...NONE.
MN...NONE.
IA...NONE.
NE...NONE.
DISCUSSION...AJP
AVIATION...08
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