Area Forecast Discussion
Issued by NWS Rapid City, SD

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000
FXUS63 KUNR 032126
AFDUNR

AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
326 PM MDT MON AUG 3 2015

.SHORT TERM...THIS EVENING THROUGH TUESDAY NIGHT
ISSUED AT 325 PM MDT MON AUG 3 2015

UPPER LEVEL ANALYSIS SHOWS CLOSED LOW OVER THE GREAT
SALT LAKE...PUSHING CLOUDS INTO THE NORTHERN PLAINS. SURFACE HIGH
PRESSURE STRETCHES ACROSS THE CENTRAL DAKOTAS WITH SOUTHEASTERLY
RETURN FLOW AROUND 10 KTS. TEMPS ARE CLIMBING INTO THE 80S.

THETA-E ADVECTION WILL INCREASE TONIGHT ACROSS WESTERN SD AHEAD OF
APPROACHING TROUGH. A BAND OF SHOWERS/STORMS ARE EXPECTED TO MOVE
INTO THE CWA FROM THE SOUTHWEST AND EXPAND NORTHEASTWARD OVERNIGHT.
WIDESPREAD SEVERE WEATHER IS NOT EXPECTED...BUT WITH ML CAPE NEAR
2000 J/KG...COULD SEE AN ISOLATED STRONG TO SEVERE STORM.

A FEW SCATTERED SHOWERS MAY LINGER INTO TUESDAY MORNING. CHANCES
INCREASE BY THE AFTERNOON AS TROUGH AXIS AND SURFACE LOW CROSS THE
REGION. BREEZY SOUTHEASTERLY WINDS WILL HELP CREATE AN UNSTABLE
ENVIRONMENT...AND WITH ML CAPE VALUES AROUND 3500 J/KG...COULD SEE
SOME ISOLATED STRONG TO SEVERE STORMS. HOWEVER...SHEAR IS VERY WEAK
AND CLOUD COVER MAY INHIBIT HEATING AND LIMIT SEVERE DEVELOPMENT.
THE MAIN THREAT WITH THESE STORMS WILL BE HEAVY RAIN AND POSSIBLE
FLASH FLOODING...AS STORM MOTION IS ONLY AROUND 10 KTS AND PWATS ARE
180 TO 200 PERCENT OF NORMAL. BEST CHANCE OF HEAVY RAIN WILL BE TO
THE NORTH AND WEST OF THE LOW ALONG AN AREA OF ENHANCED
FRONTOGENESIS...ACROSS FAR NORTHEASTERN WY...NORTHWESTERN SD...AND
THE BLACK HILLS...INCLUDING STURGIS. THEREFORE A FLASH FLOOD WATCH
WILL BE ISSUED FOR THESE AREAS FOR TUESDAY AFTERNOON AND EVENING.
STORM MOTION INCREASES SIGNIFICANTLY AFTER MIDNIGHT AND PRECIP WILL
EXIT MUCH OF THE CWA BY WEDNESDAY MORNING. HIGHS TUESDAY WILL BE IN
THE 80S...70S IN THE BLACK HILLS...AND COULD BE COOLER WITH
AFOREMENTIONED CLOUD COVER.

.LONG TERM...WEDNESDAY THROUGH MONDAY
ISSUED AT 325 PM MDT MON AUG 3 2015

ACTIVE PROGRESSIVE FLOW WILL DOMINATE IN THE PERIOD AS
LARGE SCALE RIDGING REMAINS SUBDUED. 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 THUR AND SAT BEING BEING PROGGED FOR THE HIGHEST POPS
ATTM. FASTER FLOW ALOFT WILL SUPPORT A POTENTIAL SEVERE THREAT WITH
EACH SYSTEM...HOWEVER TIMING WILL BE KEY IN ANY COVERAGE. SEASONAL
TEMPS EXPECTED IN THE PERIOD.

&&

.AVIATION...FOR THE 00Z TAFS THROUGH 00Z TUESDAY EVENING
ISSUED AT 325 PM MDT MON AUG 3 2015

SCATTERED THUNDERSTORMS WILL MOVE ACROSS THE AREA THIS
AFTERNOON THROUGH TONIGHT. MVFR CIGS/IFR VSBY EXPECTED WITH THE
STORMS...ESP INVOF THE BLACK HILLS. OTHERWISE...VFR CONDITIONS
EXPECTED.

&&

.UNR WATCHES/WARNINGS/ADVISORIES...
SD...FLASH FLOOD WATCH FROM TUESDAY AFTERNOON THROUGH TUESDAY EVENING
     FOR SDZ001-012-013-024>026-028>031-072>074.

WY...FLASH FLOOD WATCH FROM TUESDAY AFTERNOON THROUGH TUESDAY EVENING
     FOR WYZ056-057-071.

&&

$$

SHORT TERM...POJORLIE
LONG TERM...JC
AVIATION...JC



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