957
FXUS63 KFSD 200858
AFDFSD
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SIOUX FALLS SD
258 AM CST THU FEB 20 2020
SHORT TERM
(TODAY AND TONIGHT)
ISSUED AT 251 AM CST THU FEB 20 2020
A COLD NIGHT ACROSS THE REGION THANKS TO MOSTLY CLEAR SKIES AND
LIGHT WINDS. THAT SAID, WE'RE CLEARLY SEEING THE IMPACT OF SNOW
COVER ACROSS THE REGION, WITH NEARLY 10 DEGREES OF DIFFERENCE
BETWEEN AREAS WITH DEEP OR FRESH SNOW COVER AND THOSE WITH MINIMAL
AMOUNTS. WIND CHILLS ARE HOLDING NEAR OR JUST SHY OF ADVISORY
CRITERIA THANKS TO THE LIGHT WINDS. MODELS ARE STRUGGLING HOWEVER
WITH A THIN LAYER OF 900 MB MOISTURE THAT IS PROGGED BASED ON THE
RAP GUIDANCE TO SLOWLY DRIFT EAST AND SOUTHEAST THIS MORNING.
FOR TODAY, WE'LL BEGIN TO SEE MID-LVL HEIGHTS RISE, AND LOW-LVL WARM
ADVECTION INTENSIFY. AT THE SURFACE, WINDS WILL TURN MORE SOUTHERLY
THROUGH THE DAY, HELPING TEMPERATURES CLIMB IN MOST AREAS. IT WILL
BE A TRICKY TEMPERATURE FORECAST GIVEN FRESH SNOW COVER, AND HAVE
TRIED TO DRAW IN SLIGHTLY COOLER TEMPERATURES OVER NEW SNOW AND
IMMEDIATELY DOWNSTREAM FROM THOSE AREAS.
TONIGHT: WINDS REMAIN BREEZY THROUGH THE OVERNIGHT HOURS AND INTO
FRIDAY MORNING. THE RESULTING DIURNAL CURVE WILL BE MINIMAL, WITH
TEMPERATURES STEADY OR SLIGHTLY RISING AT TIMES.
LONG TERM
(FRIDAY THROUGH WEDNESDAY)
ISSUED AT 251 AM CST THU FEB 20 2020
FRIDAY: A WEAK SURFACE BOUNDARY ENTERS THE AREA EARLY FRIDAY, AS THE
CORE OF THE LOW-LVL THERMAL RIDGE MOVES OVERHEAD. TEMPERATURES
WILL REBOUND WELL ABOVE NORMAL IN SOME LOCATIONS, WITH AREAS OF
SOUTH CENTRAL SOUTH DAKOTA CHALLENGING THE 50 DEGREE MARK.
ELSEWHERE, WILL KNOCK DOWN TEMPERATURES ALONG THE FRESH 3-6" OF
SNOWPACK ALONG THE HIGHWAY 20 CORRIDOR.
SATURDAY: A WEAK MID-LVL VORTICITY MAXIMUM WILL SLIDE THROUGH
THE AREA ON SATURDAY, BRINGING AN INCREASE IN MID-LVL CLOUD
COVER. OTHERWISE THOUGH, ANOTHER DRY DAY WITH WARM TEMPERATURES IS
EXPECTED. TEMPERATURES WILL CLIMB INTO THE 40S IN MANY LOCATIONS,
DESPITE THE LIGHT WINDS.
SUNDAY: QUIET WEATHER CONTINUES INTO SUNDAY. MEDIUM RANGE GUIDANCE
CONTINUES TO SWEEP THE LARGER UPPER TROUGH THROUGH THE CENTRAL
PLAINS LATER IN THE DAY ON SUNDAY AND SUNDAY NIGHT. THE GFS REMAINS
THE NORTHERN OUTLIER WITH THIS SOLUTION, AND COULD POSSIBLY
SPREAD FLURRIES OR LIGHT SNOW THROUGH THE SOUTHERN ZONES. THE
ECMWF AND GEM HAVE MINIMAL IMPACT FOR THE AREA.
MONDAY-THURSDAY: THERE STILL REMAINS LARGE SCALE DISAGREEMENT WITH
THE SECONDARY WAVE OF ENERGY DROPPING INTO THE PLAINS FROM THE
NORTHERN ROCKIES. THE LATEST ECMWF/GEM HOLD MINIMAL IMPACT FOR THE
AREA, INSTEAD PUSHING THE ENERGY SOUTHWARD ALONG THE WESTERN
PLAINS AND ONLY BRINGING A COLD AND DRY PUSH OF AIR THROUGH THE
AREA. THE GFS IS ABOUT THE ONLY MODEL BRINGING SOME IMPACTFUL
LIGHT SNOW THROUGH THE REGION. FOR RIGHT NOW, WILL MAINTAIN THE
LOW POPS IN THE FORECAST, BUT COULD SEE THOSE TREND LOWER OVER THE
UPCOMING 24 HOURS. TEMPERATURES WILL DROP BELOW NORMAL BY THE
MIDDLE TO END OF NEXT WEEK, BUT NOTHING TOO EXTREME FOR LATE
FEBRUARY.
AVIATION
(FOR THE 00Z TAFS THROUGH 00Z THURSDAY EVENING)
ISSUED AT 556 PM CST WED FEB 19 2020
VFR CONDITIONS, ALONG WITH VARIABLE WINDS AT OR BELOW 10KT, ARE
EXPECTED THROUGH THIS FORECAST PERIOD.
FSD WATCHES/WARNINGS/ADVISORIES
SD...WIND CHILL ADVISORY UNTIL 9 AM CST THIS MORNING FOR SDZ039-040.
MN...WIND CHILL ADVISORY UNTIL 9 AM CST THIS MORNING FOR MNZ071-072-
080-081-090-097.
IA...NONE.
NE...NONE.
SHORT TERM...DUX
LONG TERM...DUX
AVIATION...JH
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