127
FXUS63 KFSD 140925
AFDFSD
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SIOUX FALLS SD
425 AM CDT MON APR 14 2025
KEY MESSAGES
- COLDER WITH SCATTERED SHOWERS/THUNDERSTORMS THIS AFTERNOON.
SOME STORMS MAY CONTAIN TINY HAIL. THERE IS A ALSO A VERY LOW
(<20%) POTENTIAL FOR A RAIN/SNOW MIX IN HIGHER ELEVATIONS OF
EAST CENTRAL SOUTH DAKOTA/SOUTHWEST MINNESOTA.
- NORTHWEST WINDS REMAIN GUSTY TODAY. WIDESPREAD GUSTS 40 TO 45
MPH ARE EXPECTED, BUT SHOWERS/STORMS HAVE POTENTIAL TO BRING
DOWN POCKETS OF 50+ MPH WINDS. A WIND ADVISORY HAS BEEN ISSUED
FOR ALL AREAS FROM 11 AM THROUGH 7 PM TODAY.
- INCREASED RAIN CHANCES (40-60%) ARE SEEN BY THURSDAY-THURSDAY
NIGHT. SCATTERED STORMS ARE POSSIBLE, BUT UNCERTAINTIES REMAIN
ON NORTHWARD EXTENT OF POTENTIAL FOR STRONG TO SEVERE STORMS.
DISCUSSION
ISSUED AT 425 AM CDT MON APR 14 2025
TODAY: GUSTY NORTHWEST WINDS REMAIN AT THE FOREFRONT OF TODAY'S
CHALLENGES. OUR ANTICIPATED OVERNIGHT SURGE OF STRONGER GUSTS
HAS COME AND GONE AND WINDS WILL EASE SLIGHTLY THROUGH DAYBREAK
TO MID MORNING. ATTENTION THEN TURNS TO AN ADVANCING SHORTWAVE
ROTATING AROUND THE BACK SIDE OF THE MID-UPPER TROUGH AS IT
MOVES SLOWLY EAST INTO THE GREAT LAKES/SOUTHWEST ONTARIO. MUCH
COLDER AIR HAS SETTLED INTO THE REGION, ESPECIALLY ALOFT WITH
SUB-ZERO 850MB TEMPERATURES OVER MOST OF THE FORECAST AREA
TODAY. THIS IS RESULTING IN LOW CONVECTIVE TEMPERATURES WITH
ADDITIONAL LIFT PROVIDED BY THE AFOREMENTIONED SHORTWAVE WHICH
WILL DROP SOUTH ACROSS THE AREA THIS AFTERNOON. EXPECT ISOLATED
TO SCATTERED SHOWERS TO EXPAND SOUTHWARD DURING THE EARLY TO MID
AFTERNOON, SLOWLY DIMINISHING AS WE APPROACH SUNSET AND THE WAVE
MOVES OFF TO THE SOUTHEAST. THE LOW FREEZING LEVEL TOPPED BY A
TALL BUT VERY SKINNY CAPE PROFILE COULD SUPPORT GRAUPEL/SMALL
HAIL WITH MORE ROBUST SHOWERS ALONG WITH A THREAT OF LIGHTNING.
OUR HIGHER ELEVATIONS IN EAST CENTRAL SOUTH DAKOTA/SOUTHWEST
MINNESOTA MAY ALSO SEE THE SURFACE-BASED "WARM" LAYER COOL
ENOUGH WITH THE CONVECTIVE ACTIVITY TO MAINTAIN A RAIN/SNOW MIX
AT TIMES, THOUGH ACCUMULATION IS NOT EXPECTED.
AS FAR AS WIND SPEEDS, GENERAL SYNOPTIC MIXING WOULD FLIRT WITH
ADVISORY-LEVEL WIND GUSTS WITH SOUNDINGS GENERALLY SUPPORTING
MIXED LAYER MOMENTUM TRANSPORT AROUND 30-35+KT. HOWEVER, TALLER
SHOWERS/STORMS WOULD TAP INTO STRONGER WINDS AND POTENTIALLY
BRING LOCALIZED GUSTS TOPPING 50 MPH TO THE SURFACE. AS SUCH,
HAVE ISSUED A WIND ADVISORY FROM LATE MORNING THROUGH ABOUT
SUNSET ACROSS THE FORECAST AREA. THE COLDER AIR MASS ALONG WITH
SCATTERED SHOWERS SHOULD KEEP HUMIDITY LEVELS ABOVE CRITICAL
LEVELS FOR MOST AREAS THIS AFTERNOON. HOWEVER, LOCATIONS ALONG
THE MISSOURI RIVER VALLEY ARE EXPECTED TO SEE LESSER COVERAGE
OF SHOWERS AS HUMIDITY VALUES DROP TO 25-30% THIS AFTERNOON AND
HAVE TRANSITIONED THE FIRE WEATHER WATCH TO A RED FLAG WARNING
IN THESE AREAS.
TONIGHT-WEDNESDAY: RELATIVELY QUIET PERIOD AS WEAK UPPER LEVEL
RIDGING BRINGING WARMER AND DRIER AIR BACK TO THE REGION. WINDS
WILL BE ON THE LIGHTER SIDE TUESDAY, ESPECIALLY WEST OF I-29
WHERE HUMIDITY LEVELS ARE AT THEIR LOWEST. ELEVATED FIRE DANGER
RETURNS WEDNESDAY AS SOUTHERLY FLOW BEGINS TO INCREASE, BUT AT
THIS TIME CONDITIONS LOOK TO REMAIN SHY OF CRITICAL LEVELS.
THURSDAY-THURSDAY NIGHT: THIS BECOMES OUR NEXT PERIOD OF FOCUS
AS THE PATTERN EVOLVES TO SOUTHWEST FLOW ALOFT. WARM ADVECTION
AND A LEAD SHORTWAVE SLIDING NORTHEAST THURSDAY MORNING COULD
PRODUCE ELEVATED SHOWERS OR STORMS DURING THE LATTER HALF OF
WEDNESDAY NIGHT INTO THURSDAY MORNING. AT THIS TIME IT APPEARS
THE POTENTIAL FOR STRONG TO SEVERE STORMS WITH THIS ACTIVITY IS
LOW, THOUGH STEEP LAPSE RATES ABOVE 850MB COULD SUPPORT SMALL
HAIL. MORE QUESTIONS AS TO HOW THINGS WILL THEN EVOLVE THROUGH
THE AFTERNOON AND EVENING, WITH MODELS SHOWING LESS AGREEMENT
THAN WAS SEEN AT THIS TIME YESTERDAY. DECENT CONSENSUS SHOWING
INCREASING MID-UPPER LEVEL WINDS LEADING TO INCREASING DEEP
LAYER SHEAR ACROSS NEBRASKA/IOWA BY LATE IN THE DAY. HOWEVER,
PLACEMENT OF THE SURFACE WARM FRONT IS UNCERTAIN (COULD BE NEAR
OR SOUTH OF HIGHWAY 20, OR LIFT AS FAR NORTH AS HIGHWAY 18 IN
NORTHWEST IOWA). A STOUT CAPPING INVERSION MAY LIMIT POTENTIAL
OF STRONGER STORMS FROM DEVELOPING NORTH OF THE BOUNDARY, SO
WHILE RAIN CHANCES ARE MODERATE (40-60%), CONFIDENCE IN DETAILS
REGARDING STRONGER STORMS IS LOW.
FRIDAY-SUNDAY: MODELS DIVERGE ON HOW THE UPPER LEVEL PATTERN
WILL EVOLVE AS WE PROGRESS INTO NEXT WEEKEND. DECENT AGREEMENT
THAT COOLER AIR WILL AGAIN SETTLE SOUTHWARD FRIDAY, BUT JUST HOW
COLD AND HOW LONG IT WILL PERSIST IS IN QUESTION. ATTENTION
THEN TURNS TO A TROUGH EJECTING OUT OF THE SOUTHERN ROCKIES.
MORE AGGRESSIVE SOLUTIONS COULD SPREAD RAIN BACK INTO THE REGION
BY SUNDAY, WHILE WEAKER/SLOWER SOLUTIONS FAVOR A DRY WEEKEND
WITH RAIN CHANCES HOLDING OFF UNTIL MONDAY OR PERHAPS SLIDING
EAST OF THE AREA ALTOGETHER.
AVIATION /06Z TAFS THROUGH 06Z TUESDAY/
ISSUED AT 1030 PM CDT SUN APR 13 2025
VFR CONDITIONS BEGIN THE TAF PERIOD. GUSTY NORTHWEST WINDS PERSIST
ACROSS THE AREA WITH GUSTS AS HIGH AS ABOUT 35 KNOTS. THESE WINDS
WILL SLOWLY WEAKEN THROUGH THE NIGHT. AT THE SAME TIME, MVFR STRATUS
WILL PUSH INTO THE AREA TONIGHT AS WELL. THE MVFR CEILINGS WILL
CONTINUE THROUGH THE MORNING HOURS TOMORROW BEFORE LIFTING BACK TO
VFR LEVELS DURING THE AFTERNOON HOURS. THIS IS THE SAME PERIOD OF
TIME THAT SCATTERED SHOWERS WILL OVERSPREAD THE AREA. AT THIS TIME,
HAVE ONLY ADDED PROB30 GROUPS TO ALL TAFS GIVEN THE SCATTERED NATURE
OF THE SHOWERS. THERE COULD BE AN ISOLATED LIGHTNING STRIKE IN THE
SHOWERS BUT CONFIDENCE IS TOO LOW TO INCLUDE MENTION OF THUNDER IN A
TAF AT THIS TIME. NORTHWEST WINDS WILL RESTRENGTHEN FOR THE
AFTERNOON HOURS WITH GUSTS AGAIN UP TO 30-40 KNOTS. SHOULD SEE WINDS
BEGIN TO WANE AND THE SCATTERED SHOWERS DISSIPATE DURING THE EVENING
HOURS TO END THE TAF PERIOD.
FIRE WEATHER
ISSUED AT 425 AM CDT MON APR 14 2025
NORTHWEST WINDS GUSTING 40-45 MPH ARE EXPECTED TO DEVELOP AGAIN
BY LATE THIS MORNING. COLDER TEMPERATURES AND SCATTERED SHOWERS
WILL RESULT IN HIGHER HUMIDITY LEVELS (35-50%) FOR MUCH OF THE
AREA, KEEPING FIRE DANGER BELOW CRITICAL LEVELS. HOWEVER, AREAS
ALONG THE MISSOURI RIVER VALLEY WILL SEE DRIER AIR WITH LOWER
CHANCES OF SHOWER ACTIVITY. RELATIVE HUMIDITY AS LOW AS 25-30%
ALONG WITH THE GUSTY WINDS WILL CREATE CRITICAL FIRE WEATHER
CONDITIONS AND A RED FLAG WARNING WILL BE IN EFFECT FROM 1 PM
THROUGH 8 PM TODAY. PLEASE NOTE THAT ANY SHOWERS WILL BRING A
POTENTIAL FOR ERRATIC STRONGER GUSTS, PERHAPS TOPPING 50 MPH,
WHICH COULD FURTHER ENHANCE FIRE SPREAD.
LIGHTER WINDS WILL EASE THE FIRE DANGER ON TUESDAY. HOWEVER,
BREEZY SOUTH WINDS AND DRY AIR WILL AGAIN PRODUCE HIGH TO VERY
HIGH GRASSLAND FIRE DANGER WEDNESDAY. THE WEEK WILL END WITH
INCREASING HUMIDITY LEVELS AS RAIN CHANCES INCREASE ACROSS THE
AREA THURSDAY INTO THURSDAY NIGHT.
FSD WATCHES/WARNINGS/ADVISORIES
SD...WIND ADVISORY FROM 11 AM THIS MORNING TO 7 PM CDT THIS EVENING
FOR SDZ038>040-050-052>071.
RED FLAG WARNING FROM 1 PM THIS AFTERNOON TO 8 PM CDT THIS
EVENING FOR SDZ050-063-068>071.
MN...WIND ADVISORY FROM 11 AM THIS MORNING TO 7 PM CDT THIS EVENING
FOR MNZ071-072-080-081-089-090-097-098.
IA...WIND ADVISORY FROM 11 AM THIS MORNING TO 7 PM CDT THIS EVENING
FOR IAZ001>003-012>014-020>022-031-032.
RED FLAG WARNING FROM 1 PM THIS AFTERNOON TO 8 PM CDT THIS
EVENING FOR IAZ031.
NE...WIND ADVISORY FROM 11 AM THIS MORNING TO 7 PM CDT THIS EVENING
FOR NEZ013-014.
RED FLAG WARNING FROM 1 PM THIS AFTERNOON TO 8 PM CDT THIS
EVENING FOR NEZ013-014.
DISCUSSION...JH
AVIATION...MEYERS
FIRE WEATHER...JH
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