417
FXUS63 KUNR 280339
AFDUNR
AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
939 PM MDT TUE MAY 27 2025
KEY MESSAGES
-DAILY CHANCES FOR SHOWERS AND A FEW STORMS THROUGH WEDNESDAY
NIGHT.
-WARMER AND DRIER THURSDAY THROUGH SUNDAY.
DISCUSSION
(THIS EVENING THROUGH TUESDAY)
ISSUED AT 226 PM MDT TUE MAY 27 2025
UPPER LEVEL ANALYSIS SHOWS A LOW OVER THE DAKOTAS AND MINNESOTA WITH
ITS ASSOCIATED TROUGH STRETCHING DOWN INTO TEXAS, A SHORTWAVE TROUGH
OVER THE CALIFORNIA COAST, AND A NARROW RIDGE EXTENDING NORTHWARD
UP THE WESTERN ROCKIES FROM NEW MEXICO INTO UTAH AND THE PACIFIC
NORTHWEST. AT THE SURFACE, A WEAK COLD FRONT EXTENDS FROM
SASKATCHEWAN, THROUGH CENTRAL MONTANA AND EASTERN IDAHO, INTO
NORTHERN NEVADA, WHILE A TROUGH EXTENDS AHEAD OF THE FRONT THROUGH
CENTRAL WYOMING. ADDITIONALLY, WEAK SURFACE HIGH PRESSURE REMAINS
OVER THE DAKOTAS. CLOUD COVER REMAINS IN PLACE ACROSS MOST OF THE
FORECAST AREA, BUT SOME BREAKS HAVE DEVELOPED OVER THE WESTERN
HALF OF THE CWA.
FOR TONIGHT AND WEDNESDAY, THE UPPER LOW DEEPENS AND MOVES SLOWLY
INTO IOWA AS THE UPPER RIDGE OVER THE INTERMOUNTAIN WEST BUILDS AND
BEGINS TO SLOWLY MOVE OVER THE ROCKIES. AN IMPULSE OVER CENTRAL
MONTANA WILL MOVE THROUGH THE WESTERN AND SOUTHERN PORTIONS OF THE
FORECAST AREA LATE TONIGHT AND WEDNESDAY. THIS IMPULSE COMBINED
WITH THE UPPER LOW TILTING BACK INTO THE AREA WILL PROVIDE SOME
LIFT AND INSTABILITY ALLOWING FOR CHANCES OF SHOWERS AND
THUNDERSTORMS. ADDITIONALLY, EAST SOUTHEAST LOW LEVEL FLOW MAY
RESULT IN SOME PATCHY FOG FOR A FEW HOURS AROUND 12Z ALONG THE
EASTERN FOOTHILLS. CLOUD COVER WILL DECREASE THROUGH THE DAY ON
WEDNESDAY, BUT OVERALL TEMPERATURES WILL REMAIN COOL (BELOW
AVERAGE).
ON THURSDAY, THE UPPER RIDGE BEGINS TO PUSH TOWARD THE AREA,
ALLOWING FOR DRY CONDITIONS. TEMPERATURES WILL GRADUALLY WARM
THURSDAY AND FRIDAY, BEFORE A SHORTWAVE TROUGH MOVES JUST NORTH OF
THE FORECAST AREA LATE FRIDAY AND FRIDAY NIGHT. HAVE OPTED TO
LEAVE POPS OUT FOR NOW AS THE MAIN FORCINGS REMAIN NORTH OF THE
AREA. HOWEVER, DEPENDING ON THE TIMING, A FEW STORMS MAY BE
POSSIBLE OVER THE HILLS AND NORTHWESTERN SOUTH DAKOTA. ALSO,
TEMPERATURES COULD BE SLIGHTLY COOLER ON SATURDAY, BUT STILL ABOVE
AVERAGE. THE RIDGE BECOMES CENTERED OVER THE FORECAST AREA ON
SUNDAY, WHICH SHOULD MAKE FOR A WARM DAY. WESTERN PORTIONS ON THE
BACKSIDE OF THE RIDGE COULD SEE SOME EVENING THUNDERSTORMS
DEPENDING ON HOW THE NEXT UPPER LOW EVOLVES OVER THE PACIFIC
NORTHWEST. OVERALL, THERE ARE SOME INDICATIONS THAT SEVERE STORMS
COULD BE POSSIBLE ACROSS THE AREA MONDAY AFTERNOON AND EVENING,
WITH COOLER TEMPERATURES ON TUESDAY.
AVIATION
(FOR THE 06Z TAFS THROUGH 06Z WEDNESDAY NIGHT)
ISSUED AT 939 PM MDT TUE MAY 27 2025
LOCALIZED MVFR CONDITIONS OVER HIGHER ELEVATIONS OF THE CENTRAL
AND SOUTHERN BLACK HILLS MAY IMPROVE THROUGH 09Z. HOWEVER,
CONDITIONS WILL LIKELY DETERIORATE TO MVFR/IFR/LIFR OVER THE
BLACK HILLS, FOOTHILLS, AND ADJACENT PLAINS 09-13Z AS LOW STRATUS
AND BR/FG DEVELOP OWING TO EASTERLY UPSLOPE FLOW. FOG AND LOW
STRATUS MAY PERSIST THRU 18Z BEFORE GRADUAL IMPROVEMENT TO VFR
FROM NORTH TO SOUTH. ALONG WITH EXPANDING LOW STRATUS, AREAS OF
SHRA/TSRA OVER NORTHEASTERN WY MAY LEAD TO LOCALIZED DETERIORATION
IN CIGS/VSBYS THRU AT LEAST THE FIRST HALF OF THE PERIOD. THIS
ACTIVITY WILL EXPAND INTO SOUTHWESTERN SD AND, LATER, SOUTH
CENTRAL SD LATE TONIGHT THROUGH TOMORROW MORNING.
UNR WATCHES/WARNINGS/ADVISORIES
SD...NONE.
WY...NONE.
DISCUSSION/KEY MESSAGES...SMITH
AVIATION...SHERBURN
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