856
FXUS63 KFSD 242252
AFDFSD
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SIOUX FALLS SD
552 PM CDT THU SEP 24 2020
SHORT TERM
(THIS EVENING THROUGH FRIDAY)
ISSUED AT 308 PM CDT THU SEP 24 2020
SHORTWAVE RIDGING BEHIND THIS MORNING'S UPPER-LEVEL TROUGH PASSAGE
WILL KEEP SKIES MOSTLY CLEAR AND WINDS RELATIVELY LIGHT THIS EVENING
AND INTO THE EARLY OVERNIGHT HOURS. AS A SURFACE LOW PRESSURE
APPROACHES FROM THE WEST, SOUTHERLY WINDS WILL INCREASE OVERNIGHT
JUST ABOVE THE NOCTURNAL INVERSION ALLOWING SOME BREEZY GUSTS TO
MIX DOWN WEST OF I-29.
FRIDAY STAYS MOSTLY CLEAR, WITH SURFACE WINDS SWITCHING TO WESTERLY
AND NORTHWESTERLY THROUGHOUT THE DAYTIME HOURS. GUSTS IN THE 20 TO
30 MPH RANGE WILL BECOME COMMON BY THE AFTERNOON. HIGH TEMPERATURES
WILL BE MILD AND IN THE UPPER 70S TO LOW 80S.
LONG TERM
(FRIDAY NIGHT THROUGH THURSDAY)
ISSUED AT 308 PM CDT THU SEP 24 2020
A BROAD LOW-AMPLITUDE TROUGH OVER THE WESTERN CONUS WILL KEEP MILD
CONDITIONS IN PLACE ON SATURDAY, WITH TEMPERATURES REMAINING ABOUT
10 DEGREES ABOVE NORMAL. THE WIND PATTERN SATURDAY CLOSELY RESEMBLES
FRIDAY'S, WITH BREEZY WINDS STARTING AS SOUTHERLY AND SWITCHING TO
NORTHWESTERLY BY THE EVENING HOURS.
A MORE ROBUST COLD FRONT MOVES THROUGH SATURDAY NIGHT INTO SUNDAY,
USHERING IN A BIGGER PATTERN CHANGE. MOISTURE IS LACKING WITH THIS
FEATURE GIVEN THE POLAR ORIGINS, SO VERY LITTLE IF ANY
PRECIPITATION IS EXPECTED. SUNDAY TEMPERATURES LOWER TO NEAR OR
JUST BELOW SEASONAL AVERAGES, WHICH COULD FEEL COOL GIVEN THE
WARMTH AS OF LATE. THE TIGHT PRESSURE GRADIENT ASSOCIATED WITH
THIS COLD AIR ADVECTION ENCOURAGES DEEPER MIXING, SO AFTERNOON
GUSTS WILL LIKELY BE IN THE 30 TO 40 MPH RANGE. THIS IS LOWER THAN
IN RECENT MODEL RUNS, BUT STILL WORTH MONITORING FOR FUTURE WIND
ADVISORY HEADLINES.
THE COOLDOWN CONTINUES ON MONDAY AS THE UPPER LEVEL TROUGH DEEPENS
OVER THE MISSISSIPPI RIVER VALLEY. HIGHS WILL BE BELOW SEASONAL
AVERAGES, WITH LOW TO MID 60S. COLD AIR ALOFT COULD HELP SUPPORT A
FEW COOL RAIN SHOWERS DURING DAYTIME HEATING, BUT PRECIPITATION
AMOUNTS WILL BE MINIMAL.
A REINFORCING SHOT OF COLD AIR ARRIVES FROM THE NORTH ON TUESDAY,
WITH THE RETURN OF GUSTY NORTH WINDS. WEDNESDAY IS FORECAST TO BE
PARTLY CLOUDY AND COOLER, WITH HIGHS IN THE 50S. WEDNESDAY NIGHT
BRINGS SOME CLEARING WITH SINKING MOTION IN THE UPPER ATMOSPHERE.
FROST IS POSSIBLE DURING THIS TIMEFRAME IF CLOUDS CLEAR
SUFFICIENTLY, WITH LOWS IN THE MID TO UPPER 30S.
AVIATION
(FOR THE 00Z TAFS THROUGH 00Z FRIDAY EVENING)
ISSUED AT 546 PM CDT THU SEP 24 2020
VFR CONDITIONS EXPECTED THROUGH THE TAF PERIOD. LIGHT
SOUTHEASTERLY WINDS TONIGHT, WITH SOME GUSTINESS AROUND KHON AFTER
05Z. IN ADDITION, INCREASING WINDS ALOFT WILL RESULT IN LOW LEVEL
WIND SHEAR AT KHON. ON FRIDAY, WINDS WILL TRANSITION TO
NORTHWESTERLY ACROSS THE AREA IN THE AFTERNOON WITH GUSTS AROUND
20 KTS AT TIMES.
FSD WATCHES/WARNINGS/ADVISORIES
SD...NONE.
MN...NONE.
IA...NONE.
NE...NONE.
SHORT TERM...VANDENBOOGART
LONG TERM...VANDENBOOGART
AVIATION...JM
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