116 FXUS63 KUNR 251809 AFDUNR AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY NATIONAL WEATHER SERVICE RAPID CITY SD 1209 PM MDT WED JUN 25 2014 .UPDATE... ISSUED AT 920 AM MDT WED JUN 25 2014 CURRENT SURFACE ANALYSIS SHOWS NEARLY STATIONARY FRONTAL BOUNDARY OVER SOUTHEAST MT...THE BLACK HILLS AREA...SOUTHWEST SD...AND NORTHERN NEB. A WEAK SURFACE LOW IS LOCATED ALONG THE BOUNDARY OVER SOUTHEAST MT. UPPER LEVEL ANALYSIS SHOWS WEAK RIDGING PASSING TO THE EAST OF THE CWA...WITH WEST-SOUTHWEST FLOW WESTWARD TO THE ROCKIES. KUDX RADAR SHOWS A FEW SHOWERS GRADUALLY DISSIPATING OVER NORTHWEST NEB AND FAR SOUTHERN SD...ASSOCIATED WITH A WEAK DISTURBANCE PASSING ACROSS. TEMPS ARE IN THE 60S AND LOWER 70S WITH EAST-SOUTHEAST WINDS GRADUALLY INCREASING. THESE WINDS ARE BRINGING INCREASING LOW LEVEL MOISTURE INTO THE AREA...WITH DEWPOINTS RISING INTO THE UPPER 50S AND LOWER 60S IN MANY AREAS. HAVE UPDATED PRIMARILY TO MAKE SOME ADJUSTMENTS TO POPS AND CLOUD COVER FOR THE LATE MORNING AND EARLY AFTERNOON HOURS. THE FORECAST FOR LATER THIS AFTERNOON INTO TONIGHT LOOKS ON TRACK...WITH THUNDERSTORMS INCREASING IN COVERAGE AND INTENSITY. THE THREAT FOR SEVERE STORMS STILL LOOKS MOST FAVORABLE ACROSS NORTHEAST WY AND MUCH OF WESTERN SD...ALONG WITH THE RISK FOR SLOW MOVING STORMS PRODUCING HEAVY RAINFALL. THE CAP WILL ERODE THE EARLIEST ACROSS NORTHEAST WY AND THE BLACK HILLS...GENERALLY BY 21Z. UPPER LEVEL FORCING LOOKS RELATIVELY WEAK UPSTREAM OF HERE...BUT SUFFICIENT TO EVENTUALLY GET STORMS GOING...ESPECIALLY WITH THE SURFACE BOUNDARY HANGING OVER THE AREA. LARGE HAIL...STRONG WIND GUSTS...AND POSSIBLY AN ISOLATED TORNADO WILL BE THE MAIN THREATS FROM SEVERE STORMS IN THE SLIGHT RISK AREA. && .SHORT TERM...TODAY THROUGH THURSDAY NIGHT ISSUED AT 338 AM MDT WED JUN 25 2014 UPPER LEVEL ANALYSIS HAS WEAK RIDGE CROSSING THE CENTRAL ROCKIES...WITH WEAK SHORTWAVE ENERGY CROSSING THE WESTERN HIGH PLAINS. AN AREA OF WEAK SHOWERS AND THUNDERSTORMS IS ENTERING THE SOUTHWEST BLACK HILLS AT THE MOMENT...AND SLOWLY MOVING TO THE NORTHEAST. AT THE SURFACE...HIGH PRESSURE IS LOCATED ACROSS NORTH DAKOTA WITH LEE TROF PRESENT FROM CENTRAL MONTANA INTO EASTERN WYOMING. TEMPERATURES AT 3 AM ARE IN THE 50S TO LOWER 60S WITH LIGHT EAST TO SOUTHEAST WINDS. PERIODS OF UNSETTLED WEATHER WILL CONTINUE THROUGH THE REMAINDER OF THE WEEK...WITH LATE TODAY...THURSDAY...AND FRIDAY LOOKING TO BE RATHER ACTIVE DAYS WITH REGARD TO SEVERE WX. TODAY...ISOLATED TO SCATTERED SHOWERS AND STORMS WILL CONTINUE THIS MORNING OVER SOUTHERN AND WESTERN PORTIONS OF THE CWA. MORE WIDESPREAD AND STRONGER ACTIVITY WILL DEVELOP LATER TODAY INTO TONIGHT AS THE NEXT SHORTWAVE MOVES INTO THE REGION. SOUTH TO SOUTHEAST WINDS WILL INCREASE LATE THIS MORNING AS SURFACE LOW PRESSURE DEVELOPS ACROSS NORTHEASTERN WYOMING. THIS WILL BRING INCREASING MOISTURE AND INSTABILITY...ESPECIALLY ACROSS NORTHEAST WYOMING AND FAR WESTERN SOUTH DAKOTA. SHEAR WILL ALSO BECOME FAVORABLE FOR SUPERCELL STORMS. THERE IS A SLIGHT RISK FOR SEVERE STORMS ACROSS NORTHEAST WYOMING AND MOST OF FAR WESTERN SOUTH DAKOTA...WITH LARGE HAIL...STRONG WIND GUSTS...AND POSSIBLY A TORNADO THE MAIN THREATS. HIGH PRECIPITABLE WATER VALUES...MOIST GROUND CONDITIONS...AND CONDITIONS FAVORABLE FOR RELATIVELY SLOW MOVING STORMS WILL INCREASE THE POTENTIAL FOR HEAVY RAINFALL AND THE POSSIBILITY OF FLASH FLOODING TODAY AND THURSDAY...ESPECIALLY DURING THE AFTERNOON AND EVENING HOURS. THURSDAY...WEAK UPPER RIDGE QUICKLY SHIFTS EAST AS STRONG UPPER TROF ENTERS THE PACIFIC NORTHWEST. UPPER LEVEL FLOW ACROSS THE NORTHERN PLAINS BECOMES SOUTHWEST WITH WEAK SHORTWAVE ENERGY CONTINUING TO CROSS THE AREA. STRONG BOUNDARY LAYER HEATING COMBINED WITH AMPLE SHEAR AND INSTABILITY SHOULD SPELL ANOTHER ROUND OF STRONG TO SEVERE THUNDERSTORMS ACROSS MOST OF THE FORECAST AREA. LARGE HAIL AND DAMAGING WINDS WILL BE THE MAIN CONCERN WITH THESE STORMS...ALONG WITH HEAVY RAINS AND POSSIBLE FLASH FLOODING. && .LONG TERM...FRIDAY THROUGH TUESDAY ISSUED AT 338 AM MDT WED JUN 25 2014 UPPER TROF WILL CONTINUE TO WORK EASTWARD THROUGH THE INTERMOUNTAIN WEST BECOMING NEGATIVELY TILTED OVER THE NORTHERN PLAINS BY FRIDAY. A SHORTWAVE EJECTING FROM THE MAIN TROF WILL PUSH A COLD FRONT THROUGH THE FORECAST AREA. BEST CHANCE FOR SVR STORMS WILL BE OVER THE EASTERN ZONES BASED ON THE CURRENT TIMING OF THE COLD FRONT PASSAGE. UNSETTLED WEATHER EXPECTED TO CONTINUE ON SATURDAY... BEFORE MAIN UPPER TROF AXIS PUSHES THROUGH ON SUNDAY AND BRINGS A DRIER PATTERN INTO THE REGION. TEMPS WILL BE FAIRLY WARM ON FRIDAY AHEAD OF THE COLD FRONT AND THEN WILL COOL SLIGHTLY THROUGH THE WEEKEND. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z THURSDAY) ISSUED AT 1207 PM MDT WED JUN 25 2014 A STRONG IMPULSE WITH INCREASING LOW LEVEL MOISTURE WILL SUPPORT SCT SHRA/TS ACROSS NORTHEASTERN WY AND WESTERN SD THIS AFTERNOON/EVENING. SOME STORMS WILL BE CAPABLE OF GUSTY WINDS AND LARGE HAIL. MVFR/IFR CONDS WILL BE POSSIBLE IN AN NEAR TS WED AFT/EVEN. && .HYDROLOGY... ISSUED AT 338 AM MDT WED JUN 25 2014 HIGH PRECIPITABLE WATER VALUES AND CONDITIONS FAVORABLE FOR RELATIVELY SLOW MOVING STORMS WILL INCREASE THE POTENTIAL FOR HEAVY RAINFALL AND THE POSSIBILITY OF FLOODING ON WEDNESDAY AND THURSDAY...ESPECIALLY IN THE AFTERNOON AND EVENING. THUS A FLASH FLOOD WATCH IS IN EFFECT FOR FAR NORTHEAST WY AND MUCH OF FAR WESTERN SD FOR WEDNESDAY AFTERNOON THROUGH THURSDAY EVENING. && .UNR WATCHES/WARNINGS/ADVISORIES... SD...FLASH FLOOD WATCH THROUGH THURSDAY EVENING FOR SDZ001-002-012- 013-024>026-028>031-072>074. WY...FLASH FLOOD WATCH THROUGH THURSDAY EVENING FOR WYZ054-056-057- 071. && $$ UPDATE...26 SHORT TERM...15 LONG TERM...MLS AVIATION...13 HYDROLOGY...MLS