487
FXUS63 KFSD 090351
AFDFSD
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SIOUX FALLS SD
1051 PM 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 20% 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 EXPECTED SUNDAY, AND MAY CONTINUE INTO
NEXT WEEK.
DISCUSSION
ISSUED AT 247 PM CDT THU MAY 8 2025
CURRENT: LOOKING AT GOES VISIBLE SATELLITE IMAGERY, SKIES ARE MOSTLY
CLEAR OVER THE PLAINS THIS AFTERNOON. SKIES ARE EXPECTED TO REMAIN
MOSTLY CLEAR THROUGH THE OVERNIGHT. TAKING A LOOK AT THE MODEL
DATA, ALOFT WE SEE A STRONG RIDGE WITH AN EMBEDDED REX BLOCK
PATTERN CENTERED OVER THE CENTRAL UNITED STATES. THIS PATTERN IS
GOING TO PREVAIL THROUGH THE WEEKEND AND INTO THE EARLY PART OF
NEXT WEEK. WINDS AT THE SURFACE AND THROUGH THE MID-LEVELS ARE
LIGHT, LESS THAN 10 KTS. HIGHS FOR THIS AFTERNOON ARE EXPECTED
TO CLIMB INTO MID 70S TO LOW 80S, WITH THE COOLEST TEMPERATURES
OVER SOUTHWESTERN MINNESOTA. LOW WINDS AND EFFICIENT RADIATIONAL
COOLING WILL ALLOW LOWS TO FALL INTO THE MID 40S TO LOW 50S.
FRIDAY: FRIDAY WILL BE ANOTHER WARM AND MOSTLY DRY DAY. WAA FROM THE
SURFACE THROUGH AROUND THE 700 MB LAYER COMBINED WITH INCREASING
GEOPOTENTIAL HEIGHTS WILL RESULT IN VERY WARM TEMPERATURES AT THE
SURFACE. FOR CONTEXT, GEOPOTENTIAL HEIGHTS FOR THE MID TO UPPER
LAYERS OF THE ATMOSPHERE WILL BE IN THE 90TH TO THE 97TH PERCENTILE
FOR CLIMATOLOGY ACCORDING TO THE ESATS TABLES. THIS SUPPORTS
AFTERNOON HIGHS CLIMBING TO THE MID TO UPPER 80S, APPROXIMATELY 15-
20 DEGREES WARMER THAN AVERAGE FOR THIS TIME OF YEAR. THOUGH
TEMPERATURES WILL BE WARM, WE DO NOT LOOK TO BREAK ANY RECORDS,
WHICH ARE IN THE MID 90S. LOWS WILL BE IN THE 50S.
FRIDAY EVENING A WEAK WAVE AND ASSOCIATED SURFACE LOW AND COLD FRONT
WILL PASS THROUGH THE REGION. THIS MAY SPARK A FEW LIGHT SHOWERS AND
THUNDERSTORMS. HOWEVER, THE TREND IN GUIDANCE THE PAST FEW RUNS HAS
BACKED OFF ON PRECIPITATION CHANCES. A DEEP, DRY SUBCLOUD LAYER WILL
LIKELY PREVENT MOST OF THE PRECIPITATION FROM REACHING THE GROUND.
AS SUCH, MOST WILL SEE LITTLE IF ANY RAINFALL AT ALL. IN TOTAL, ONLY
A FEW HUNDREDTHS TO A TENTH OF AN INCH OF RAINFALL IS EXPECTED. THE
AREA MOST LIKELY TO SEE RAINFALL IS NORTH OF I-90 IN SOUTHWESTERN
MINNESOTA. DUE TO LACK OF CONFIDENCE, HAVE KEPT POPS LESS THAN 20%.
IF ANY SHOWERS DO DEVELOP, LAPSE RATES ARE WEAK, LESS THAN 7 C/KM,
AND SHEAR IS LESS THAN 10 KTS, SO SEVERE WEATHER IS NOT EXPECTED.
HOWEVER, A COUPLE HUNDRED J/KG OF CAPE MAY BE ENOUGH FOR A FEW
LIGHTNING STRIKES AND RELATIVELY HEAVIER SHOWERS.
THE WEEKEND: THE BLOCKING PATTERN MENTIONED EARLIER WILL DRIFT
SOUTH, BUT WE WILL REMAIN UNDER HIGH PRESSURE WITH A STRONG
RIDGE OVERHEAD. ANOMALOUSLY HIGH (99TH PERCENTILE TO MAXIMUM OF
CLIMATOLOGY) GEOPOTENTIAL HEIGHTS CONTINUE THROUGH THE WEEKEND.
WAA ON LIGHT SOUTHERLY WINDS AND MOSTLY CLEAR SKIES WILL
MAINTAIN WARM TEMPERATURES THROUGH THE WEEKEND. HIGHS FOR
SATURDAY WILL BE IN THE MID TO UPPER 80S. SUNDAY HIGHS WILL
AGAIN BE IN THE MID TO UPPER 80S, WITH SOME AREAS POSSIBLY
SEEING LOW 90S.
BEGINNING EARLY SUNDAY MORNING, SOUTHERLY WINDS WILL INCREASE IN
RESPONSE TO A TIGHTENING OF THE SPG BETWEEN A LOW PRESSURE TO OUR
NORTHEAST, AND A HIGH PRESSURE TO OUR SOUTHEAST. FREQUENT GUSTS OF
35-40 MPH ARE EXPECTED FOR AREAS WEST I-29. OCCASIONAL GUSTS TO
35 MPH ARE ALSO POSSIBLE FOR THIS REGION. FOR AREAS TO THE
EAST, SLIGHTLY WEAKER GUSTS OF 25-35 MPH ARE EXPECTED. IN
ADDITION, A VERY DRY AIR MASS WILL SET UP OVER THE REGION,
RESULTING IN RELATIVE HUMIDITY VALUES FOR SUNDAY AFTERNOON
FALLING TO 15-25%. DESPITE THE FACT THAT MUCH OF THE REGION HAS
GREENED UP, CONDITIONS LIKE THESE STILL RESULT IN DANGEROUS FIRE
WEATHER CONDITIONS. FIRES CAN CATCH AND CARRY QUICKLY WITH
WINDS AS STRONG AS THEY ARE EXPECTED TO BE FOR SUNDAY AFTERNOON.
AFTER COORDINATION WITH NEIGHBORS, HAVE DECIDED TO ISSUE A FIRE
WEATHER WATCH FOR SUNDAY AFTERNOON.
NEXT WEEK: HOT, DRY, AND WINDY CONDITIONS CONTINUE INTO THE FIRST
HALF OF NEXT WEEK. ADDITIONAL FIRE WEATHER HEADLINES MAY BECOME
NECESSARY. MONDAY THE STRONG WINDS SPREAD FURTHER EAST.
FREQUENT GUSTS 30-40 MPH ARE POSSIBLE ACROSS THE ENTIRE REGION.
HIGHS MONDAY AND TUESDAY ARE EXPECTED TO REACH THE UPPER 80S TO
LOW 90S. THE AIR MASS REMAINS VERY DRY, WITH RELATIVE HUMIDITY
VALUES 20-25%. WINDS WILL EASE SLIGHTLY FOR TUESDAY, WITH GUSTS
30-35 MPH POSSIBLE ACROSS THE REGION. RELATIVE HUMIDITY RECOVERS
SLIGHTLY BUT REMAINS NEAR CRITICAL, 25-30%. WEAK CAA WEDNESDAY
MORNING LIMIT HIGHS SLIGHTLY TO THE UPPER 70S TO MID 80S.
RELATIVE HUMIDITY RECOVERS TO AROUND 30% OR HIGHER, EASING FIRE
WEATHER CONCERNS.
BY WEDNESDAY AFTERNOON WE SEE THE UPPER RIDGE BEING PUSHED TO THE
EAST AS A STRONG UPPER TROUGH MOVES OUT OF THE ROCKIES AND ONTO THE
PLAINS. CHANCES FOR RAIN RETURN TO THE FORECAST FOR THURSDAY AND
FRIDAY
AVIATION /06Z TAFS THROUGH 06Z SATURDAY/
ISSUED AT 1049 PM CDT THU MAY 8 2025
VFR CONDITIONS EXPECTED THROUGH THE TAF PERIOD. WE'LL SEE MAINLY
CLEAR SKIES FOR THE REST OF THE NIGHT, WITH CLOUDS INCREASING FROM
NORTHWEST TO SOUTHEAST THROUGH THE DAY ON FRIDAY AS A FAIRLY NARROW
BAND OF HIGH CLOUDS MOVES ACROSS THE AREA. SCATTERED CUMULUS
CLOUDS ALSO LOOK TO DEVELOP FRIDAY AFTERNOON AND THEN FADE INTO
THE EVENING WITH LOSS OF DAYTIME HEATING. CAN'T RULE OUT AN
ISOLATED SHOWER OR THUNDERSTORM IN THE AFTERNOON MAINLY IN
SOUTHWEST MINNESOTA, BUT CHANCES ARE TOO LOW (<20%) TO WARRANT
MENTIONING IN THE TAFS. HOWEVER, IF SHOWERS DO DEVELOP, THEY
COULD DROP A QUICK 30-35 KT GUST.
OTHERWISE, WINDS WILL BE FAIRLY LIGHT (IN THE 5-10 KT RANGE) THROUGH
MOST OF THE PERIOD. WINDS WILL GRADUALLY SHIFT FROM THE SOUTHEAST TO
THE NORTHWEST THROUGH THE DAY ON FRIDAY AS A COLD FRONT MOVES ACROSS
THE AREA. THIS FRONT MAY STALL NEAR AND NORTH OF KSUX, HOLDING BACK
THE WIND DIRECTION CHANGE ACROSS THE HIGHWAY-20 CORRIDOR UNTIL VERY
LATE IN THE PERIOD OR JUST AFTERWARDS.
FIRE WEATHER
ISSUED AT 247 PM CDT THU MAY 8 2025
DRY AND MOSTLY CLEAR CONDITIONS TODAY THROUGH SATURDAY. WINDS WILL
BE LIGHT, GENERALLY LESS THAN 10 MPH. DIRECTION WILL BE VARIABLE DUE
TO THE PASSAGE OF A COLD FRONT FRIDAY AFTERNOON INTO THE EVENING.
HIGHS WILL BE IN THE 70S-80S TODAY, AND THE MID 80S FRIDAY AND
SATURDAY.
SUNDAY WILL BE HOT, DRY, AND WINDY. HIGHS WILL CLIMB INTO THE MID
80S TO LOW 90S. WINDS WILL BE OUT OF THE SOUTH-SOUTHWEST AND
INCREASE THROUGH THE AFTERNOON. FREQUENT GUSTS OF 35-40 MPH, ARE
EXPECTED FOR AREAS WEST I-29. OCCASIONAL GUST TO 45 MPH ARE
ALSO POSSIBLE FOR THIS REGION. FOR AREAS TO THE EAST, SLIGHTLY
WEAKER GUSTS OF 25-35 MPH ARE EXPECTED. IN ADDITION, A VERY DRY
AIR MASS WILL SET UP OVER THE REGION, RESULTING IN RELATIVE
HUMIDITY VALUES FOR SUNDAY AFTERNOON FALLING TO 15-25%. A FIRE
WEATHER WATCH IS IN EFFECT SUNDAY FROM 11 AM UNTIL 10 PM.
HOT, DRY, AND WINDY CONDITIONS CONTINUE MONDAY AND TUESDAY. HIGHS
FOR BOTH DAYS WILL BE IN THE MID 80S TO LOW 90S. WINDS WILL SLACKEN
SLIGHTLY ON MONDAY, BUT CONTINUE TO GUST 30-40 MPH. RELATIVE
HUMIDITY WILL REMAIN IN NEAR CRITICAL TO CRITICAL RANGE, 20-25%.
TUESDAY HUMIDITY WILL BEGIN TO RECOVER SOMEWHAT, BUT THERE WILL
REMAIN PATCHY AREAS OF LESS THAN 25%. WINDS WILL AGAIN BE GUSTING 30-
35 MPH. ADDITIONAL FIRE HEADLINES MAY BE NECESSARY. WE WILL
CONTINUE TO MONITOR THE TRENDS.
WEDNESDAY CONDITIONS BEGIN TO IMPROVE WITH COOLER HIGHS IN THE 80S,
AND RELATIVE HUMIDITY RECOVERING TO 30% OR GREATER.
FSD WATCHES/WARNINGS/ADVISORIES
SD...FIRE WEATHER WATCH FROM SUNDAY MORNING THROUGH SUNDAY EVENING
FOR SDZ038>040-052>062.
MN...FIRE WEATHER WATCH FROM SUNDAY MORNING THROUGH SUNDAY EVENING
FOR MNZ071-072-080-081-089-090-097-098.
IA...NONE.
NE...NONE.
DISCUSSION...AJP
AVIATION...SAMET
FIRE WEATHER...AJP
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