393
FXUS63 KFSD 080814
AFDFSD
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SIOUX FALLS SD
314 AM CDT THU MAY 8 2025
KEY MESSAGES
- WARM AND MOSTLY DRY WEATHER CONTINUES THROUGH SATURDAY WITH
HIGHS IN THE UPPER 70S TO THE MID 80S.
- ISOLATED SHOWERS AND STORMS (LESS THAN 25% CHANCE) FRIDAY
AFTERNOON AND EVENING NORTH OF I-90. SEVERE WEATHER IS NOT
EXPECTED.
- VERY WARM AND BREEZY SUNDAY INTO EARLY NEXT WEEK. EXPECT DAILY
HIGHS IN THE 80S WITH SOME LOCATIONS APPROACHING 90 DEGREES.
CRITICAL FIRE DANGER IS POSSIBLE SUNDAY INTO AT LEAST MONDAY.
DISCUSSION
ISSUED AT 310 AM CDT THU MAY 8 2025
CURRENTS THROUGH TONIGHT: MOSTLY CLEAR THIS MORNING, WITH
TEMPERATURES IN THE MID 40S TO UPPER 50S. WE'LL COOL INTO THE 40S
AND LOWER 50S FOR MOST OF THE AREA WITH LIGHT WINDS AND MOSTLY CLEAR
CONDITIONS THROUGH DAYBREAK.
WINDS REMAIN LIGHT AND SOMEWHAT VARIABLE THROUGH THE DAY WITH NOT
MUCH FLOW AT THE SURFACE OR ALOFT WITH RIDGING IN PLACE. IF
DIRECTION IS PREVAILING, ANTICIPATE WINDS WILL BE EAST TO SOUTHEAST
WITH SURFACE HIGH PRESSURE OFF TO THE EAST. EXPECT MOSTLY CLEAR
SKIES AGAIN, WITH HIGH TEMPERATURES IN THE 70S TO NEAR 80. LOWS
TONIGHT IN THE MID/UPPER 40S TO LOWER 50S. DRY CONDITIONS CONTINUE.
FRIDAY: MOST STAY DRY ON FRIDAY WITH RIDGING IN PLACE ALOFT.
HOWEVER, MAY SEE SOME ISOLATED SHOWERS AND THUNDERSTORMS DROP SOUTH
THROUGH THE AFTERNOON AND EVENING HOURS ALONG A FRONTAL BOUNDARY
AND WEAK WAVE ALOFT. WE SHOULD WARM UP ENOUGH WITH HIGHS IN THE MID
AND UPPER 80S MOST PLACES TO BREAK ANY MEAGER CAP IN PLACE. NOT
EXPECTING ANY SEVERE WEATHER WITH SHEAR LACKING, MODEST MID LEVEL
LAPSE RATES, AND CAPE BELOW 600 J/KG FROM MOST MODELS; HOWEVER, DRY
SUB CLOUD LAYER COULD LEAD TO ISOLATED GUSTY WINDS. THIS DRY SUB
CLOUD LAYER LEADS TO LOWER CONFIDENCE IN COVERAGE OF POPS, SO WILL
LIMIT TO LESS THAN 25% FOR NOW (RAISED FROM PREVIOUS/NBM). RAINFALL
AMOUNTS OF LESS THAN A TENTH OF AN INCH, ALTHOUGH MAY SEE ISOLATED
HIGHER AMOUNTS IN THUNDERSTORMS AND IF WE CAN SATURATE THE LOWER
LEVELS. SHOWERS/STORMS DROP SOUTH THROUGH THE EVENING TOWARD THE
I-90 CORRIDOR, BUT SHOULD DIMINISH NEAR/AFTER SUNSET AS WE LOSE
PEAK HEATING. LOWS IN THE LOWER TO MID 50S.
THE WEEKEND-MONDAY: ANOMALOUSLY STRONG RIDGING WITH A REX BLOCK BUILDS
INTO THE WEEKEND, WHICH WILL KEEP CONDITIONS DRY. CONFIDENCE REMAINS
HIGH IN ABOVE NORMAL TEMPERATURES WITH HIGHS WELL INTO THE 80S WITH
SOME LOCATIONS EVEN APPROACHING THE 90 DEGREE MARK BY SUNDAY. THIS
IS ABOUT 15 DEGREES ABOVE NORMAL. WINDS SHOULD REMAIN FAIRLY LIGHT
ON SATURDAY WHICH WILL TEMPER FIRE CONCERNS DESPITE MINIMUM HUMIDITY
VALUES BELOW CRITICAL THRESHOLDS. WARM AND DRY CONDITIONS COMBINE
WITH STRONG SOUTHERLY WINDS ON SUNDAY (GUSTS TO 40 MPH) AS SPG
COMPRESSES BETWEEN SURFACE LOW TO OUR NORTH AND SURFACE HIGH TO OUR
SOUTHEAST. WITH WARM TEMPERATURES, STRONG WINDS, AND RH VALUES IN
THE TEENS, CRITICAL FIRE DANGER IS POSSIBLE FOR MOTHER'S DAY. STRONG
WINDS CONTINUE OVERNIGHT INTO MONDAY ALONG WITH THE WARM
TEMPERATURES AS REX BLOCK/RIDGE SLIDE EAST THROUGH THE DAY. RH
VALUES WON'T BE AS LOW ON MONDAY, BUT DEFINITELY ANOTHER PERIOD OF
POSSIBLE CRITICAL FIRE WEATHER CONDITIONS WITH SOUTHERLY WIND GUSTS
TO 40 MPH. FIRE WEATHER WILL BE LARGELY DEPENDENT ON HOW GREEN WE
ARE - WITH LOWER GREENNESS VALUES CORRESPONDING TO VERY HIGH TO
EXTREME FIRE DANGER. AS OF NOW, LOW TO MODERATE (LESS THAN 45%)
CHANCES SUNDAY AND MONDAY FOR WIND GUSTS TO EXCEED 45 MPH WITH THE
SLIGHTLY HIGHER AND MORE WIDESPREAD CHANCES ON MONDAY. LOWS THROUGH
THE WEEKEND ALSO REMAIN ON THE WARM SIDE - IN THE MID/UPPER 50S TO
LOWER 60S.
TUESDAY ONWARD: TUESDAY REMAINS ON THE WARM SIDE, WITH MID AND UPPER
LEVEL TROUGHING SLIDING EAST OUT OF THE ROCKIES BY TUESDAY NIGHT.
SURFACE LOW EJECTS OUT OF CO AROUND THIS TIME AS WELL. 08.00Z
GUIDANCE IS SPLIT ON THE EVOLUTION OF THIS TROUGH - THE ECMWF IS A
TOUCH SLOWER AND MORE OPEN WITH THE MID/UPPER TROUGH WHILE THE
GFS/CANADIAN WIND THIS UP A BIT MORE AND KEEP THE LOW A BIT FURTHER
TO THE SOUTH. REGARDLESS, WILL KEEP AN EYE ON THIS PERIOD FOR SHOWER
AND STORM CHANCES AS WELL AS CONTINUED STRONG WINDS. TEMPERATURES
COOL SLIGHTLY BY MID WEEK.
AVIATION /06Z TAFS THROUGH 06Z FRIDAY/
ISSUED AT 1025 PM CDT WED MAY 7 2025
VFR CONDITIONS EXPECTED THROUGH THE TAF PERIOD. WINDS WILL BE LIGHT
EAST TO SOUTHEASTERLY TONIGHT INTO THURSDAY EVENING.
FSD WATCHES/WARNINGS/ADVISORIES
SD...NONE.
MN...NONE.
IA...NONE.
NE...NONE.
DISCUSSION...SG
AVIATION...JM
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