839
FXUS63 KUNR 231109
AFDUNR
AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
509 AM MDT SAT OCT 23 2021
DISCUSSION
(TODAY THROUGH FRIDAY)
ISSUED AT 129 AM MDT SAT OCT 23 2021
INCREASINGLY PROGRESSIVE AND ACTIVE FLOW CAN BE EXPECTED IN THE
PERIOD AS THE POLAR JET BEGINS TO SAG FURTHER SOUTH, SUPPORTING
IMPULSE LADEN FLOW OVER THE REGION. THE FIRST IN A SERIES OF FAST
MOVING SYSTEMS IS NOW PROPAGATING ACROSS WESTERN MT. THIS SYSTEM
CONTINUES TO SUPPORT LEE SIDE PRESSURE FALLS WITH GUSTY SE WINDS
MATERIALIZING OVER PORTIONS OF THE REGION. INCREASING LL MOISTURE
PER SE FLOW IS SUPPORTING LOW CLOUDS AND SOME FOG ACROSS PORTIONS
OF NW SD AND THIS WILL CONTINUE TO BE THE CASE THROUGH MORNING.
SUSTAINED MOIST SE FLOW MAY FORCE LOW CLOUDS AND TO LINGER THROUGH
MUCH OF THE DAY OVER NW SD. HENCE, CONTINUED TO SIDE WITH LOWER
HIGHS THERE, WITH MORE UNCERTAINLY PER TEMPS IN THE MIDDLE SECTION
OF THE CWA GIVEN CONCERNS ON LOW CLOUDS WITH INCREASING MID
CLOUD. UPPER IMPULSE WILL PROPAGATE INTO THE REGION TONIGHT AND
SUPPORT SOME RAIN SHOWERS AS THERMAL PROFILES WILL REMAIN QUITE
WARM. FLOW WILL THEN SHIFT NW BEHIND A COOL FRONT SUNDAY WITH
LINGERING SHOWERS PUSHING OUT OF THE AREA. WARMING WILL THEN ENSUE
HEAD OF THE NEXT SYSTEM, WITH HIGHS IN THE 60S AND 70S MONDAY AND
TUES, ALBEIT BREEZY. THE NEXT CHANCE FOR MAINLY RAIN SHOWERS WILL
BE TUE-TUE NIGHT AS A STRONGER LONG WAVE TROUGH SHIFTS THROUGH
THE REGION. SEASONAL TEMPS WITH HIGHS IN THE 50S AND 60S LOOK
LIKELY FOR THE REMAINDER OF THE WEEK WITH NEAR ZONAL FLOW IN
PLACE. INDICATIONS REMAIN FOR A STRONGER COLD FRONT NEXT WEEKEND.
HOWEVER, FORECAST CONFIDENCE IN THIS REMAINS QUITE LOW GIVEN
COMPLICATED FAST FLOW AND POOR MODEL AGREEMENT AND RUN TO RUN
CONSISTENCY.
AVIATION
(FOR THE 12Z TAFS THROUGH 12Z SUNDAY MORNING)
ISSUED AT 507 AM MDT SAT OCT 23 2021
AREAS OF IFR CONDITIONS DUE TO LOW STRATUS AND PATCHY FOG WILL
CONTINUE THROUGH 14-16Z THIS MORNING. IMPROVEMENT TO VFR
CONDITIONS IS EXPECTED BY LATE MORNING SATURDAY, CONTINUING
THROUGH THE EVENING. ADDITIONAL LOW STRATUS/FOG POSSIBLE SATURDAY
NIGHT. EXPECT GUSTY SOUTHEAST WINDS ON THE SD PLAINS TODAY.
UNR WATCHES/WARNINGS/ADVISORIES
SD...NONE.
WY...NONE.
DISCUSSION...JC
AVIATION...EAGAN
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