Area Forecast Discussion
Issued by NWS Rapid City, SD

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000
FXUS63 KUNR 311720
AFDUNR

AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
1120 AM MDT SUN MAY 31 2015

.SHORT TERM...TODAY THROUGH MONDAY NIGHT
ISSUED AT 220 AM MDT SUN MAY 31 2015

UPPER LEVEL ANALYSIS SHOWS A RIDGE BUILDING OVER THE WESTERN
CONUS...AND A WAVE PUSHING THROUGH THE RIDGE INTO THE NORTHERN
PLAINS. SHOWERS AND THUNDERSTORMS CONTINUE TO MOVE THROUGH THE
CWA...MAINLY OVER NORTHWESTERN SD. WINDS ARE VARIABLE AROUND 10
KTS...AND TEMPS ARE IN THE 40S AND 50S.

SHOWERS WILL QUICKLY MOVE OUT OF WESTERN SD THIS MORNING. THERMAL
RIDGE WILL SHIFT EASTWARD INTO THE CWA TODAY...ALTHOUGH MODELS
CONTINUE TO TREND A BIT COOLER. HIGHS WILL RANGE FROM THE MID 60S
ACROSS CENTRAL SD TO THE MID 70S FARTHER WEST. SOME MARGINAL CAPE
DEVELOPS OVER THE WARMER PARTS OF THE CWA THIS AFTERNOON...AND SO
SHOWERS AND STORMS ARE AGAIN POSSIBLE OVER NORTHEAST WY AND THE
BLACK HILLS LATER TODAY.

RIDGE AXIS MOVES OVER THE CWA MONDAY...AND TEMPS WILL WARM INTO THE
70S AND 80S. FAST-MOVING LOW OVER THE PACIFIC NORTHWEST WILL QUICKLY
BREAK DOWN THE RIDGE AND EJECT ENERGY INTO THE NORTHERN PLAINS
MONDAY AFTERNOON AND EVENING...PRODUCING SHOWERS AND THUNDERSTORMS.
SOME OF THESE STORMS MAY BE SEVERE...WITH MLCAPE VALUES OF 2000-3000
J/KG EXPECTED OVER WESTERN SD AND 0-6 KM BULK SHEAR VALUES OF 40-50
KTS OVER NORTHWESTERN/CENTRAL SD BY MONDAY AFTERNOON. PRECIPITABLE
WATER VALUES ARE OVER AN INCH...AND SO SOME OF THESE STORMS MAY
PRODUCE HEAVY RAIN THAT MIGHT AGGRAVATE FLOODING CONDITIONS.

.LONG TERM...TUESDAY THROUGH SATURDAY
ISSUED AT 220 AM MDT SUN MAY 31 2015

MODELS SEEM TO BE IN FAIRLY GOOD AGREEMENT FOR THE WEEK WITH THE
RIDGE AXIS SHIFTING EAST OF THE FORECAST AREA ON
TUESDAY...BRINGING SOUTHWEST FLOW TO THE NORTHERN HIGH PLAINS AS A
TROUGH DEEPENS ALONG THE WEST COAST. TOWARD THE END OF THE WEEK
THE UPPER TROUGH CLOSES OFF AN UPPER LOW. ENERGY EJECTING FROM THE
WESTERN TROUGH WILL BRING CHANCES FOR SHOWERS AND THUNDERSTORMS
THROUGH THE WEEKEND. STRONG TO SEVERE STORMS ARE POSSIBLE TUESDAY
AFTERNOON/EVENING AS A WAVE PASSING THROUGH THE RIDGE COMBINES
WITH DECENT SHEAR AND MLCAPE VALUES OF OVER 2500 J/KG.
OVERALL...EXPECT STRONG TO SEVERE STORMS TO BE POSSIBLE THROUGH
THE WEEK CONSIDERING THE FLOW PATTERN AND THE TIME OF THE YEAR.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z MONDAY)
ISSUED AT 1120 AM MDT SUN MAY 31 2015

TSRA WILL REDEVELOP THIS AFTN/EVNG ACRS NERN WY AND THE BLKHLS
AREA...WITH MVFR CONDITIONS IN HEAVIER PCPN.

&&

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

$$

SHORT TERM...POJORLIE
LONG TERM...MLS
AVIATION...13


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