Area Forecast Discussion
Issued by NWS Rapid City, SD

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FXUS63 KUNR 050355
AFDUNR

AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
955 PM MDT TUE AUG 4 2015

.UPDATE...
ISSUED AT 456 PM MDT TUE AUG 4 2015

HAVE UPDATED THE FORECAST TO DROP THE FLASH FLOOD WATCH FOR THE
WRN SD PLAINS. LATEST WATER VAPOR IMAGES AND SHORT-TERM GUIDANCE
SUGGEST THE BEST FORCING FOR ASCENT WILL MOVE ACROSS NERN WY/SERN
MT...AS WELL AS TO THE SOUTH ACROSS NEB. THIS WILL LEAVE MUCH OF
WRN SD IN-BETWEEN THESE TWO AREAS AND THUS WITH A LESSER CHANCE OF
TSRA AND FLASH FLOODING.

&&

.SHORT TERM...THIS EVENING THROUGH WEDNESDAY NIGHT
ISSUED AT 209 PM MDT TUE AUG 4 2015

UPPER LOW IS SPINNING OVER EASTERN WY AS IT GRADUALLY TRANSITIONS
EASTWARD. OTHER THAN A FEW WEAK BUT RAINY THUNDERSTORMS OVER THE
NORTHERN HILLS AND BEAR LODGE MOUNTAINS...MOST OF THE ACTIVITY IS
CURRENTLY OUTSIDE THE CWA. TEMPS ARE RISING INTO THE 80S.

STILL EXPECTING SCATTERED SHOWERS AND THUNDERSTORMS LATE THIS
AFTERNOON AND THIS EVENING...BUT THE SYSTEM IS LOOKING DRIER THAN
PREVIOUSLY SO DECREASED POPS SIGNIFICANTLY ACROSS THE EASTERN CWA.
INGREDIENTS ARE STILL CONDUCIVE TO SLOW-MOVING HEAVY RAIN PRODUCING
THUNDERSTORMS...AND SO WHILE NOT A COMPLETE WASHOUT IS
EXPECTED...PLACES UNDER THE SCATTERED STORMS MAY SEE HEAVY RAIN WITH
THE POTENTIAL FOR FLASH FLOODING. INSTABILITY IS SUFFICIENT FOR
ISOLATED STRONG TO SEVERE STORMS...BUT SHEAR IS VERY WEAK AND SO
ORGANIZED SEVERE WEATHER IS STILL NOT EXPECTED. PRECIP WILL END
OVERNIGHT AS WAVE EXITS THE REGION.

MUCH OF WEDNESDAY WILL BE DRY BEFORE THE NEXT UPPER WAVE PASSES
THROUGH MAINLY WEDNESDAY NIGHT...WITH CHANCES OF SHOWERS AND
THUNDERSTORMS INCREASING IN THE AFTERNOON FROM WEST TO EAST. IN THE
AFTERNOON THE BEST CHANCE FOR AN ISOLATED STRONG TO SEVERE STORM
WILL BE OVER THE HILLS. THEN AS THE WAVE PUSHES EASTWARD INTO THE
AREA DURING THE EVENING...COULD BE ISOLATED STRONG TO SEVERE
STORMS OVER CENTRAL SD WITH ML CAPE NEAR 2000 J/KG AND 0-6 KM
SHEAR INCREASING TO 40 KTS. HOWEVER...WIDESPREAD ORGANIZED SEVERE
WEATHER IS NOT EXPECTED AND STORMS SHOULD REMAIN BELOW SEVERE
CRITERIA FOR THE MOST PART. HIGHS WEDNESDAY WILL BE IN THE
80S...WITH 70S IN THE BLACK HILLS.

.LONG TERM...THURSDAY THROUGH TUESDAY
ISSUED AT 209 PM MDT TUE AUG 4 2015

ACTIVE PROGRESSIVE FLOW WILL DOMINATE IN THE PERIOD AS LARGE
SCALE RIDGING REMAINS SUBDUED FOR MOST OF THE PERIOD. THIS WILL
SUPPORT PERIODIC CHANCES FOR SHOWERS AND THUNDERSTORMS AS A SERIES
OF TROUGHS PUSH THROUGH THE REGION. LL MOISTURE WILL BE MORE THAN
SUFFICIENT GIVEN WEAK SOUTHWARD PROTRUSION OF DRY AIR WITH STAUNCH
RETURN FLOW PER EACH SYSTEM. CARRIED LOW CHANCE POPS THROUGH MUCH
OF THE PERIOD...WITH A STRONGER SYSTEM EXPECTED THROUGH THE REGION
THIS WEEKEND SUPPORTING THE HIGHEST POPS SAT/SAT NIGHT. FASTER
FLOW ALOFT WILL SUPPORT A POTENTIAL SEVERE THREAT WITH EACH
SYSTEM...HOWEVER TIMING WILL BE KEY IN ANY COVERAGE. SEASONAL
TEMPS CAN BE EXPECTED FOR MOST OF THE PERIOD. HOWEVER...GROWING
INDICATIONS IN DETERMINISTIC AND ENSEMBLE PROGS FOR WESTERN/
CENTRAL CONUS RIDGING EARLY NEXT WEEK...WHICH WOULD SET THE STAGE
FOR MUCH WARMER CONDS IN THAT TIME FRAME.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z WEDNESDAY NIGHT)
ISSUED AT 952 PM MDT TUE AUG 4 2015

SHOWERS AND THUNDERSTORMS WILL DIMINISH 06-09Z OVER NWRN SD.
VFR CONDITIONS GENERALLY EXPECTED THROUGH THE PERIOD...BUT SOME
IFR CIGS/VSBYS MAY CREEP INTO SCNTRL SD AROUND 12Z AS FOG/STRATUS
DEVELOP ACROSS NEB AND MOVE NWD. OTHERWISE...ISOLD TSRA ARE
POSSIBLE OVER THE BLKHLS AND NERN WY IN THE AFTN/EVNG...AND MAY BE
ASSOCIATED WITH MVFR CIGS/VSBYS.

&&

.UNR WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
WY...NONE.
&&

$$

UPDATE...BUNKERS
SHORT TERM...POJORLIE
LONG TERM...JC
AVIATION...BUNKERS



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