672  
FXUS63 KUNR 230850  
AFDUNR  
 
AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY  
NATIONAL WEATHER SERVICE RAPID CITY SD  
250 AM MDT SAT AUG 23 2025  
   
KEY MESSAGES  
 
- MILD TEMPERATURES INTO NEXT WEEK.  
 
- MAINLY DRY. A FEW SHOWERS/STORMS POSSIBLE OVER THE SOUTHERN  
HILLS AND FAR SOUTHERN AREAS THROUGH EARLY NEXT WEEK.  
 
- HIGHER CHANCES FOR SHOWERS AND STORMS THURSDAY THROUGH FRIDAY.  
 
 
   
DISCUSSION  
(TODAY THROUGH FRIDAY)  
ISSUED AT 121 AM MDT SAT AUG 23 2025  
 
UPPER LEVEL ANALYSIS HAS A LOW OVER THE NORTHERN GREAT LAKES/  
SOUTHERN CANADA WITH AN AREA OF HIGH PRESSURE OVER THE FOUR  
CORNERS AND A NEGATIVELY TILTED RIDGE EXTENDING INTO THE PACIFIC  
NORTHWEST. AT THE SURFACE, HIGH PRESSURE CENTERED OVER CENTRAL  
MONTANA IS BUILDING INTO THE NORTHWESTERN PORTION OF THE FORECAST  
AREA. A FEW SHOWERS/STORMS HAVE FORMED OVER THE SOUTHWESTERN  
PORTION OF THE FORECAST AREA -- FROM SOUTH OF GILLETTE TO  
NEWCASTLE TO CUSTER TO PINE RIDGE. THESE SHOWERS LOOK TO BE  
INTERACTING WITH RESIDUAL MOISTURE CONVERGENCE, SOME THETA-E  
ADVECTION AND BOUNDARY LAYER CONVERGENCE.  
 
FOR TODAY, EXPECT SHOWERS/STORMS TO DISSIPATE EARLY THIS MORNING,  
LEAVING BEHIND SOME MID-LEVEL CLOUDS OVER THE SOUTHWESTERN HALF  
OF THE FORECAST AREA AND CLEAR SKIES ACROSS THE NORTHWESTERN  
PORTION OF THE AREA. TEMPERATURES WILL BE MILD, AS DRIER AND  
COOLER AIR PUSHES SOUTHWARD IN RESPONSE TO THE SURFACE HIGH  
PUSHING EASTWARD THROUGH THE DAY.  
 
A WEAK WAVE WILL ROUND THE UPPER RIDGE TONIGHT AS SUBTROPICAL  
MOISTURE ADVECTS INTO THE FAR SOUTHERN POTIONS OF THE FORECAST  
AREA. WARM AIR ADVECTION COMBINED WITH A STRENGTHENING LOW-LEVEL  
JET MAY RESULT IN A FEW SHOWERS/STORMS OVER THE FAR SOUTHERN  
PORTION OF THE AREA.  
 
FOR SUNDAY, MILD AND DRY CONDITIONS ARE EXPECTED AS THE UPPER  
RIDGE LOCKS INTO PLACE OVER THE DESERT SOUTHWEST AND NORTHWEST  
UPPER FLOW CONTINUES. ANY CONVECTIVE ACTIVITY SUNDAY NIGHT SHOULD  
STAY JUST SOUTH OF THE AREA.  
 
ENSEMBLE MODEL CONSENSUS FOR THE FIRST HALF OF THE WEEK KEEPS THE  
AREA IN NORTHWEST FLOW WITH OCCASIONAL ENERGY ROUNDING THE RIDGE,  
BRINGING SLIGHT CHANCES FOR SHOWERS/STORMS TO THE SOUTHWESTERN  
POTIONS OF THE AREA, LEAVING THE NORTHWESTERN HALF DRY. 850 TEMPS  
ARE NEAR NORMAL FOR THE END OF AUGUST, SO THE MILD CONDITIONS WILL  
CONTINUE.  
 
BY MIDWEEK, THE RIDGE LOOKS TO BREAK-DOWN AND SHIFT EAST, BRINGING  
A SURGE OF MONSOONAL MOISTURE INTO THE AREA. A WEAK SHORTWAVE  
LOOKS TO MOVE THROUGH THE AREA THURSDAY/FRIDAY. HIGHER (BUT NEAR  
NORMAL) PRECIPITABLE WATER VALUES WOULD INDICATE THIS WOULD BE  
OUR NEXT SHOT FOR APPRECIABLE MOISTURE FROM SHOWERS/STORMS.  
 
 
   
AVIATION  
(FOR THE 06Z TAFS THROUGH 06Z SATURDAY NIGHT)  
ISSUED AT 1042 PM MDT FRI AUG 22 2025  
 
VFR CONDITIONS WILL PREVAIL AT BOTH TAF SITES NEXT 24HRS. BROKEN  
MID CLOUDS STILL PREVAIL AT BOTH SITES, BUT RAP WILL SEE CLOUDS  
BECOMING SCATTERED AROUND 3AM. HOWEVER, BROKEN MID CLOUDS AROUND  
10KFT WILL RETURN FOR THE DAY TIME HOURS. SKIES WILL BECOME  
SCATTERED CIRRUS AT RAP AFTER 00Z. GCC WILL HAVE BROKEN MID  
CLOUDS AROUND 10KFT THROUGH MOST OF THE PERIOD BUT THEN SHOULD  
BECOME SCATTERED CIRRUS AT 00Z TOMORROW EVENING. NORTHERLY WINDS  
WILL PREVAIL AT BOTH SITES BUT EXPECTING GCC TO BECOME SOUTHEAST  
TOMORROW, THEN BACK TO NORTHEAST TOMORROW EVENING. NORTH TO  
NORTHEAST WINDS WILL CONTINUE FOR RAP THROUGH TOMORROW AND  
TOMORROW EVENING.  
 
 
   
UNR WATCHES/WARNINGS/ADVISORIES  
 
SD...NONE.  
WY...NONE.  
 
 
 
 
DISCUSSION/KEY MESSAGES...SMITH  
AVIATION...AUTEN  
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