082
FXUS63 KUNR 220433
AFDUNR
AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
1033 PM MDT WED MAY 21 2025
KEY MESSAGES
- FROST ADVISORY ISSUED FOR PORTIONS OF NORTHWEST SOUTH DAKOTA FOR
THURSDAY MORNING. WITH LOWS DROPPING INTO THE LOWER 30S SOME
PLACES, AREAS OF FROST IS LIKELY.
- A BRIEF WARMUP FOR THURSDAY MOST AREAS, CONTINUING INTO FRIDAY
FOR PORTIONS OF NORTHEAST WY AND SOUTHWEST SD. STILL A FEW
THUNDERSTORMS POSSIBLE THURSDAY NIGHT AND FRIDAY NIGHT.
- MORE WIDESPREAD SHOWERS AND THUNDERSTORMS MOVE BACK INTO THE
AREA FOR THE WEEKEND, WITH HIGH TEMPERATURES RETURNING TO MUCH
BELOW AVERAGE FOR THIS TIME OF YEAR. HIGHS WILL STRUGGLE TO GET
OUT OF THE 50S SATURDAY AND SUNDAY.
DISCUSSION
(THIS EVENING THROUGH WEDNESDAY)
ISSUED AT 247 PM MDT WED MAY 21 2025
SHORT TERM (THROUGH THURSDAY NIGHT)...STRATUS HOLDING FIRM FROM
NORTHERN PERKINS IN ZIEBACH COUNTIES THIS AFTERNOON KEEPING TEMPS IN
THE 40S STILL THERE. MEANWHILE MORE CONVECTIVE CLOUDS ASSOCIATED
WITH MID LEVEL FORCING CO-LOCATED WITH AN AREA OF INSTABILITY ALOFT
HAVE GENERATED SHOWERS AND ISOLATED THUNDERSTORMS ACROSS MAINLY THE
SOUTHERN HILLS AND PORTIONS OF NORTHEAST WY. CONVECTIVE ALLOWING
MODELS STRUGGLED WITH THIS SCENARIO INITIALLY BUT HAVE FINALLY
CAUGHT ON, AND THESE SHOWERS AND STORMS SHOULD DISSIPATE AFTER
SUNSET WITH SKIES CLEARING THEREAFTER. WITH GOOD RADIATIONAL COOLING
AFTER MIDNIGHT, DO EXPECT WINDS TO LIGHTEN AND TEMPERATURES TO DROP
INTO THE 30S MOST PLACES. NEAR THE ND BORDER WHERE ALTHOUGH CLOUDS
WILL BE LAST TO CLEAR, TEMPS WILL DROP INTO THE LOW 30S. PATCHY TO
AREAS OF FROST WILL BE LIKELY AND A FROST ADVISORY HAS BEEN ISSUED
FOR THOSE COUNTIES IN NORTHWEST SD. TRANSITORY UPPER RIDGING WILL
MOVE INTO THE NORTHERN PLAINS THURSDAY WITH LARGER SCALE
SUBSIDENCE PREVALENT ACROSS MOST OF THE AREA. THIS WILL LEAD TO
GOOD INSOLATION ACROSS THE AREA AND AFTERNOON TEMPS RETURNING TO
NEAR AVERAGE FOR THIS TIME OF YEAR, IN THE UPPER 60S TO LOW 70S.
THE FASTER UPPER FLOW OVER THE NORTHERN ROCKIES WILL CREATE LOW
PRESSURE IN THE LEE OF THE MOUNTAINS AND THE RESPONSE WILL BE FOR
WINDS TO TURN TO SOUTHERLY. THE NEXT UPPER LEVEL PV ANOMALY AND
ASSOCIATED LARGE SCALE ASCENT WILL MOVE INTO THE HIGH PLAINS LATE
IN THE DAY THURSDAY AND WILL ENHANCE THE OROGRAPHIC LIFT ENOUGH TO
GENERATE A FEW THUNDERSTORMS OVER THE BLACK HILLS AND THE
ADJACENT PLAINS THURSDAY NIGHT.
FRIDAY THROUGH THE WEEKEND...THIS INITIAL UPPER PV ANOMALY WILL
MOVE QUICKLY OUT OF THE REGION WHICH WILL ALLOW FOR GOOD SUNSHINE
ACROSS THE WESTERN AND SOUTHERN PORTION OF THE FORECAST AREA. IN
RESPONSE, HIGH TEMPERATURES WILL JUMP INTO THE 70S THERE FRIDAY,
WHILE TEMPS WILL HOLD IN THE 50S WHERE CLOUD COVER REMAINS FURTHER
NORTH. SOUTHERLY WINDS WILL CONTINUE TO BRING IN ADDITIONAL
MOISTURE AND AS THE MUCH LARGER SYSTEM MOVES INTO THE GREAT BASIN
BY SATURDAY, THUNDERSTORM CHANCES WILL INCREASE ONCE AGAIN AND
WILL BE MORE WIDESPREAD THROUGH THE WEEKEND. TEMPS WILL REMAIN
WELL BELOW AVERAGE ACROSS THE AREA SATURDAY THROUGH MONDAY, AND
WILL ONLY BE IN THE 50S MOST AREAS THIS WEEKEND UNDER PLENTY OF
CLOUDS AND INTERMITTENT SHOWERS AND THUNDERSTORMS.
AVIATION
(FOR THE 06Z TAFS THROUGH 06Z THURSDAY NIGHT)
ISSUED AT 1031 PM MDT WED MAY 21 2025
VFR CONDITIONS ARE EXPECTED THROUGH THE TAF FORECAST PERIOD.
UNR WATCHES/WARNINGS/ADVISORIES
SD...FROST ADVISORY UNTIL 7 AM MDT THURSDAY FOR SDZ001-002-013-014-
078.
WY...NONE.
DISCUSSION/KEY MESSAGES...STOPPKOTTE
AVIATION...15
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