850
FXUS63 KUNR 310000
AFDUNR
AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
600 PM MDT THU JUL 30 2026
KEY MESSAGES
- MARGINAL TO SLIGHT (LEVEL 1-2 OUT OF 5) RISK OF SEVERE
THUNDERSTORMS THIS AFTERNOON/EVENING WITH THE PRIMARY RISK OF
DAMAGING WINDS, BUT LARGE HAIL MAY ALSO OCCUR.
- AFTER "COOLER" TEMPERATURES TODAY AND FRIDAY, VERY HOT WEATHER
RETURNS FOR THE WEEKEND WITH THE HOTTEST DAY SUNDAY.
- ELEVATED (SATURDAY) TO CRITICAL (SUNDAY) FIRE WEATHER
CONDITIONS EXPECTED THIS WEEKEND.
DISCUSSION
(THIS AFTERNOON THROUGH WEDNESDAY)
ISSUED AT 1105 AM MDT THU JUL 30 2026
16Z SURFACE ANALYSIS HAD WEAK LOW OVER THE NE PANHANDLE WITH A
BOUNDARY INTO CENTRAL SD PER 0.5KM 1-MINUTE VISIBLE SATELLITE
LOOP. COLD FRONT WAS LOCATED FROM WESTERN ND INTO WESTERN WY.
WATER VAPOUR LOOP HAD SHORTWAVE TROUGH OVER NORTHERN WY WITH 80KT
JET STREAK. THESE FEATURES STARTING TO FORCE CU/TCU/TS ALONG THE
SURFACE BOUNDARY WITH EVIDENCE OF DECENT LIFT AHEAD OF THE
SHORTWAVE OVER NORTHEASTERN WY/EASTERN MT. CONCERN THIS
AFTERNOON/EVENING IS SEVERE WEATHER.
THIS AFTERNOON/EVENING, SHORTWAVE TROUGH MOVES EAST AS
CONVERGENCE ALONG THE SURFACE BOUNDARIES INCREASE. MID-LEVEL FLOW
INCREASES EFFECTIVE SHEAR TO 25-35KTS WITH LOCALLY HIGHER AMOUNTS
OVER CENTRAL SD. STRONG BUOYANCY WILL DEVELOP THIS AFTERNOON,
ESPECIALLY EAST OF THE BLACK HILLS. INITIAL STORM MODE MAY BE
CELLULAR WITH LARGE HAIL POTENTIAL, BUT THE TREND WILL BE TOWARD
SEVERE CLUSTERS/LINEAR SEVERE CONVECTION AS STORM COLD POOLS
CONGEAL. PRIMARY THREAT WILL BE DAMAGING WINDS GUSTS (70+ MPH).
LOOKING FOR A FAIRLY EARLY START THIS AFTERNOON WITH CAMS FOCUSING
ON THE CENTRAL/SOUTHERN BLACK HILLS AND CENTRAL SD THIS AFTERNOON
AND THEN LEMMON TO WINNER BY EVENING AS THE MAIN SHORTWAVE WRAPS
THROUGH THE CWA. PWATS WILL BE 150-200% OF NORMAL EAST OF THE
BLACK HILLS, SO LOCALLY HEAVY RAIN AND POTENTIAL FLASH FLOODING
MAY OCCUR. ACTIVITY WANES OVERNIGHT. TEMPERATURES WILL BE NEAR
GUIDANCE.
A WEAK SHORTWAVE MOVES THROUGH FRIDAY, BUT DRIER AIR WILL BE
FILTERING INTO THE CWA, SO POPS SHOULD BE LIMITED TO OUR HIGHER
TERRAIN AREAS.
HOT TO VERY HOT WEATHER RETURNS FOR THE WEEKEND WITH THE
PREPONDERANCE OF ENSEMBLE GUIDANCE GIVING HIGHS NEAR 110F FOR SOME
FOLKS SUNDAY. MUCH DRIER AIR IN PLACE, SO THUNDERSTORM CHANCES
WILL BE UNMENTIONABLE. COOLER WEATHER RETURNS MONDAY WITH ACTUAL
"COOL" AIR IN PLACE FOR THE MIDDLE OF NEXT WEEK PER FLATTENING
UPPER RIDGE AND WEST/NORTHWEST FLOW ALOFT FOR THE NORTHERN PLAINS.
AVIATION
(FOR THE 00Z TAFS THROUGH 00Z FRIDAY EVENING)
ISSUED AT 600 PM MDT THU JUL 30 2026
THUNDERSTORM CHANCES HAVE LIKELY ENDED FOR THE NIGHT AT KGCC AND
KRAP, WITH A LINE OF GUSTY STORMS CONTINUING TO TRACK EAST ACROSS
MOST OF OUR SOUTH DAKOTA PLAINS. BRIEF DROPS TO MVFR AND
GUSTY/ERRATIC WINDS TO 40KTS WILL BE POSSIBLE WITH THIS LINE AS IT
CONTINUES EAST THROUGH ABOUT 05Z/11PM. BEHIND IT, STRONG NORTHWEST
WINDS WILL IMPACT KRAP FOR THE NEXT SEVERAL HOURS AS A FRONT
CROSSES THE AREA, WITH GUSTS TO 30KTS. OUTSIDE OF THUNDERSTORMS,
VFR CONDITIONS ARE EXPECTED. MOVING INTO TONIGHT, OUR SOUTH
DAKOTA PLAINS MAY GET FAIRLY MOIST WITH SEVERAL SOURCES OF
GUIDANCE PROJECTING RH VALUES OVER 90 PERCENT, BUT LITTLE SUPPORT
EXISTS AT THIS TIME FOR FOG (INCLUDING NBM/HRRR/MOS VSBY OUTPUT).
SOME LOW STRATUS WILL BE POSSIBLE THROUGH EAST OF KRAP, PERHAPS TO
MVFR. FINALLY, FOR FRIDAY...VFR CONDITIONS ARE CURRENTLY
FORECAST. SOME POTENTIAL FOR ISOLATED THUNDERSTORMS EXISTS DURING
THE AFTERNOON, BUT CONSENSUS ON COVERAGE, TIMING, AND PLACEMENT
ACROSS THE CAMS IS VERY POOR AT THIS TIME WITH A COUPLE OF THEM
STAYING ALMOST COMPLETELY DRY. WILL WATCH UPDATES AS WE GO FORWARD
TO SEE IF BETTER AGREEMENT EMERGES AND WHETHER A PROB30 IS NEEDED
AT EITHER KGCC OR KRAP.
FIRE WEATHER
ISSUED AT 1105 AM MDT THU JUL 30 2026
STRONG/SEVERE THUNDERSTORMS ARE EXPECTED THIS AFTERNOON/EVENING
WITH STRONG GUSTY, ERRATIC WINDS AS THE PRIMARY THREAT. ELEVATED
(SATURDAY) TO CRITICAL (SUNDAY) FIRE WEATHER CONDITIONS ARE
EXPECTED THIS WEEKEND. MINIMUM RELATIVE HUMIDITY WILL DROP INTO
THE UPPER SINGLE DIGITS/TEENS SATURDAY IN THE WEST AND SUNDAY OVER
MUCH OF THE AREA. WINDS SATURDAY WILL BE MARGINALLY GUSTY FOR
CRITICAL FIRE WEATHER, BUT SHOULD BE MORE ROBUST ON SUNDAY PER
VERY DEEP BOUNDARY LAYER MIXING.
UNR WATCHES/WARNINGS/ADVISORIES
SD...NONE.
WY...NONE.
DISCUSSION...HELGESON
AVIATION...KSMITH
FIRE WEATHER...HELGESON
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