514
FXUS63 KUNR 081624
AFDUNR
AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
1024 AM MDT THU MAY 8 2025
KEY MESSAGES
- NEAR RECORD HIGH TEMPERATURES SUNDAY/MONDAY
- THUNDERSTORM CHANCES LATE TODAY, FRIDAY AFTERNOON, SUNDAY
AFTERNOON INTO NEXT WEEK
- ELEVATED FIRE WEATHER CONDITIONS SATURDAY THROUGH TUESDAY
DISCUSSION
(TODAY THROUGH WEDNESDAY)
ISSUED AT 143 AM MDT THU MAY 8 2025
07Z SURFACE ANALYSIS HAD WEAK RIDGE OVER THE EASTERN HALF OF THE
CWA WITH RETURN FLOW OVER THE WEST AHEAD OF A SURFACE TROUGH FROM
CENTRAL MT INTO SOUTHERN ID. WATER VAPOUR LOOP HAD WEAK RIDGE OVER
THE NORTHERN PLAINS. A FEW CIRRUS CLOUDS PASSING BY OVER FAR
SOUTHERN PORTIONS OF THE CWA. PLENTY OF STARS ELSEWHERE. MAIN
SHORT TERM FORECAST CONCERN WILL BE SURFACE TROUGH AND THEN UPPER
RIDGE FOR THE WEEKEND INTO EARLY NEXT WEEK.
TODAY/FRIDAY, UPPER RIDGE SLOWLY AMPLIFIES FROM THE SOUTHWEST
CONUS INTO THE NORTHERN PLAINS. SURFACE TROUGH SLIPS INTO THE FAR
NORTHWEST REACHES OF THE CWA EARLY THIS EVENING WITH <250J/KG MEAN
SBCAPE. CAMS SUGGEST ISOLATED CONVECTION WITH GUSTY WINDS MAY
DEVELOP ALONG SURFACE TROUGH, ALTHOUGH RISING HEIGHTS WILL ACT
AGAINST MUCH DEVELOPING. HAVE ADDED LOW POPS TO ACCOUNT. TROUGH
CONTINUES SOUTHEAST FRIDAY, THEN STALLING/WASHING OUT OVER CENTRAL
WY TOWARD THE SD/NE BORDER. IT MAY BE THE FOCUS FOR DIURNALLY
DRIVEN CONVECTION FRIDAY AFTERNOON/EVENING, ESPECIALLY NEAR THE
BLACK HILLS PER TERRAIN EFFECTS. ~500J/KG MEAN SBCAPE PER SPC
HREF WITH LIMITED 0-6KM BULK SHEAR, BUT WITH DEEPLY MIXED
BOUNDARY LAYER/DCAPE. GUSTY WINDS MAY OCCUR WITH ANY CONVECTION.
TEMPERATURES WILL BE NEAR GUIDANCE.
SATURDAY THROUGH MONDAY, UPPER/THERMAL RIDGE BUILDS INTO THE
NORTHERN PLAINS. FORECAST LOWER TROPOSPHERIC THERMAL PROFILES
THAT ARE ANOMALOUSLY WARM (90TH+ PERCENTILE PER EFI) WILL BRING A
TASTE OF SUMMER TO THE CWA. LREF GIVES 40-70% 90F+ MAXT FOR THE
WESTERN SD PLAINS SUNDAY/MONDAY WITH NBM IN THE 60-100% RANGE.
NEAR RECORD/RECORD HIGH TEMPERATURES ON TAP. RIGHT NOW, SATURDAY
AND MOST OF SUNDAY LOOKS DRY, BUT LEE TROUGH MAY SLIP INTO THE
AREA SUNDAY NIGHT/MONDAY, POSSIBLY BECOMING THE FOCUS FOR HIGH-
BASED CONVECTION.
TUESDAY THROUGH THE REST OF THE NEXT WEEK, UNSETTLED WEATHER
EXPECTED WITH A COOLING TREND AS UPPER TROUGH MOVES INTO CENTRAL
NORTH AMERICA AND HANGS OUT. BENEFICIAL QPF MAY DEVELOP (40%
CHANCE >0.50" WEDNESDAY/THURSDAY PER LREF).
AVIATION
(FOR THE 18Z TAFS THROUGH 18Z FRIDAY)
ISSUED AT 1024 AM MDT THU MAY 8 2025
VFR CONDITIONS ARE EXPECTED THROUGH THE FORECAST PERIOD.
FIRE WEATHER
ISSUED AT 143 AM MDT THU MAY 8 2025
UNSEASONABLY WARM TEMPERATURES WILL DEVELOP SATURDAY, PERSISTING
THROUGH TUESDAY. MINIMUM RELATIVE HUMIDITIES AS LOW AS THE TEENS
ARE EXPECTED, ESPECIALLY SUNDAY/MONDAY. DEEP BOUNDARY LAYER MIXING
WILL BRING GUSTY SOUTHERLY WINDS AT TIMES. THUS, ELEVATED FIRE
WEATHER CONDITIONS FORESEEN WITH ANY FIRE WEATHER WATCHES OR RED
FLAG WARNINGS DEPENDENT ON FUEL STATUS.
UNR WATCHES/WARNINGS/ADVISORIES
SD...NONE.
WY...NONE.
DISCUSSION/KEY MESSAGES...HELGESON
AVIATION...WONG
FIRE WEATHER...HELGESON
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