828
FXUS63 KUNR 031124
AFDUNR
AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
524 AM MDT SUN MAY 3 2026
KEY MESSAGES
- ISOLATED TO SCATTERED SHOWERS AND THUNDERSTORMS EXPECTED SUNDAY,
WITH THE EARLY MORNING AND MID-TO-LATE AFTERNOON PERIODS LOOKING
MOST ACTIVE.
- COLD FRONT DROPS THROUGH MONDAY, BRINGING GUSTY WINDS.
- MEAN NORTHWEST FLOW ALOFT BRINGS UNSETTLED WEATHER THROUGH MUCH
OF NEXT WEEK.
UPDATE
ISSUED AT 1025 PM MDT SAT MAY 2 2026
MASSAGED THE LATEST NBM POPS AND QPF IN THE FORECAST FOR TONIGHT
AND SUNDAY, MOSTLY TO LIGHTLY TAMPER DOWN ANY CONVECTIVE
CONTAMINATION/BULLSEYES AND KEEP AMOUNTS LIGHT, WHILE REDUCING
POPS OVER THE BLACK HILLS REGION TO GENERALLY FALL UNDER 50% AND
ALSO BROADBRUSH LIGHT POPS OUTWARD TO GIVE SLIGHTLY BETTER
AREAL COVERAGE TO MENTIONS OF SHOWERS AND STORMS. ALL OF THIS
BETTER ENCOMPASSES THE RANGE OF SOLUTIONS IN THE LATEST HREF CAMS
AND BETTER REFLECTS THE SHOWERY NATURE OF THIS ACTIVITY. STILL
EXPECTING SOME POTENTIAL FOR ELEVATED EMBEDDED THUNDER OVERNIGHT,
AND THEN PERHAPS A DECENT STORM OR TWO SUNDAY AFTERNOON GENERALLY
FROM NORTHEAST WY DOWN ACROSS THE BLACK HILLS INTO THE SOUTHWEST SD
PLAINS, ALTHOUGH LIMITED CAPE STILL SEEMS LIKE A LIMITING FACTOR.
STILL, MODEL SOUNDINGS SHOW AS MUCH AS 800 J/KG SBCAPE ALONG WITH
SOME DCAPE AND STEEP LOW-LEVEL LAPSE RATES WITH A RELATIVELY DRY
SURFACE, AND AT LEAST 25KTS OF DEEP-LAYER SHEAR. A COUPLE STORMS
MAY PRODUCE WIND GUSTS OF 40-50 MPH.
DISCUSSION
(THIS EVENING THROUGH SATURDAY)
ISSUED AT 1242 PM MDT SAT MAY 2 2026
18Z SURFACE ANALYSIS HAD LOW OVER NORTHEASTERN ND WITH COLD FRONT
INTO FAR NORTHERN WY/NORTHWEST SD, JUST ENTERING THE FAR
NORTHWEST REACHES OF THE CWA. WATER VAPOUR MATINEE HAD NORTHWEST
FLOW ALOFT WITH A COUPLE OF WEAK EMBEDDED SHORTWAVES HEADING FOR
THE NORTHERN PLAINS. NOT MUCH CU PER 0.5KM VISIBLE LOOP EARLY THIS
AFTERNOON (EVEN WITH WELL-MIXED 18Z KUNR SOUNDING - IT IS QUITE
DRY), BUT WEAK WAVE OVER ND SHOULD ASSIST A FEW MORE CU AND THE
POTENTIAL FOR ISOLATED -SHRA LATER THIS AFTERNOON OVER CENTRAL SD.
TONIGHT, COLD FRONT EXITS THE CWA WITH WEAK COLD AIR ADVECTION.
BEHIND IT AHEAD OF WEAK SHORTWAVE, EXPECT A NARROW BAND OF WEAK
800-600MB FRONTOGENESIS/THETA-E ADVECTION AND A TOUCH OF MUCAPE.
SHOULD BE SUFFICIENT FOR WEAK ELEVATED CONVECTION ACROSS
NORTHEASTERN WY/WEST-CENTRAL SD OVERNIGHT. SPC HREF PAINTBALLS
SUPPORT.
PRECIPITATION SHOULD WANE SUNDAY MORNING, BUT ADDITIONAL
-SHRA/TS WILL DEVELOP IN THE AFTERNOON PER MEAN 500J/KG SBCAPE AND
LIMITED SBCIN. BLACK HILLS LIKELY THE ORIGIN GIVEN TERRAIN
INFLUENCE, CONFIRMED BY HREF. MODEST 0-6KM BULK SHEAR COULD POP AN
ACTIVE STORM OR TWO, BUT WEAK BUOYANCY WILL LIMIT POTENTIAL.
CONVECTION DIES DOWN SUNDAY NIGHT.
SECOND COLD FRONT ARRIVES MONDAY WITH A STRONGER EMBEDDED
SHORTWAVE. RESULT WILL BE SOME SHOWERS ALONG WITH GUSTY NORTHWEST
WINDS PER PROBABILISTIC GUIDANCE (40-60% CHANCE 45MPH GUSTS FROM
K2WX-KRAP), ALTHOUGH ISALLOBARIC FORCING ISN'T THAT IMPRESSIVE.
CAN'T RULE OUT A FEW LIGHTNING STRIKES AS WELL AS SOME SNOW MIXING
IN UP HIGH, BUT IMPACTFUL SNOW ACCUMULATION IS NOT EXPECTED.
TUESDAY THROUGH SATURDAY, NORTHWEST FLOW ALOFT WILL BRING A SERIES
OF DISTURBANCES/FRONTS THROUGH THE CWA. TEMPERATURES 5-10F BELOW
NORMAL TUESDAY RISING TO 5-10F ABOVE BY SATURDAY.
AVIATION
(FOR THE 12Z TAFS THROUGH 12Z MONDAY MORNING)
ISSUED AT 521 AM MDT SUN MAY 3 2026
ISOLATED TO SCATTERED SHOWERS WILL CONTINUE THROUGH THE AFTERNOON
FROM NORTHEASTERN WYOMING THROUGH THE BLACK HILLS AREA THROUGH
SOUTHWESTERN SOUTH DAKOTA. A FEW THUNDERSTORMS MAY DEVELOP THIS
AFTERNOON, AS WELL. OTHERWISE VFR CONDITIONS ARE EXPECTED THROUGH
THE FORECAST PERIOD.
FIRE WEATHER
ISSUED AT 1242 PM MDT SAT MAY 2 2026
NEAR CRITICAL FIRE WEATHER CONDITIONS WILL CONTINUE THIS
AFTERNOON PER MINIMUM RELATIVE HUMIDITY IN THE TEENS AND WEST
(AHEAD OF COLD FRONT)/NORTHWEST WINDS (BEHIND COLD FRONT) AT 15-
25MPH.
UNR WATCHES/WARNINGS/ADVISORIES
SD...NONE.
WY...NONE.
UPDATE...KSMITH
DISCUSSION/KEY MESSAGES...HELGESON
AVIATION...13
FIRE WEATHER...HELGESON
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