Area Forecast Discussion
Issued by NWS Rapid City, SD

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FXUS63 KUNR 270932
AFDUNR

AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
332 AM MDT WED MAY 27 2015

.SHORT TERM...TODAY THROUGH THURSDAY NIGHT
ISSUED AT 308 AM MDT WED MAY 27 2015

WATER VAPOR SHOWS UPPER LOW OVER WA WITH NEGATIVELY TILTED WAVE
ROTATING ROTATING THROUGH MT/WY. AT THE SFC...HIGH IS CENTERED
OVER THE CNTRL PLAINS WITH TROF TAKING SHAPE OVER ERN MT/ERN WY.
SCT SHRA/TSTMS EXTEND FROM THE NEB PANHANDLE INTO FAR SWRN SD IN
REGION OF LOW/MID LVL THETA-E ADVECTION AHEAD OF UPPER WAVE.

TODAY...UPPER WAVE WILL CONTINUE ITS NEWD PROGRESSION WITH SFC LOW
DEVELOPING OVER THE BLKHLS BY MIDDAY. MLCAPE EXPECTED TO INCREASE
TO NEAR 1000J/KG OVER MUCH OF THE CWFA WITH CIN ERODING QUICKLY BY
LATE MRNG OVER NERN WY AND FAR WRN SD. CONVECTION WILL INTIATE
EARLY IN THE HIGHER TERRAIN OF THE BLKHLS AS WELL AS NERN
WY...THEN INTENSIFY AS IT SHIFTS EWD ACROSS THE WRN SD PLAINS. AN
AREA OF ENHANCED MLCAPE OF NEAR 1500J/KG ALONG WITH BETTER SHEAR
WILL DEVELOP ALONG A DEVELOPING WMFNT EXTENDING FROM THE BLKHLS
LOW INTO CNTRL SD AND MAY RESULT IN A FEW SVR STORMS...AND CANT
RULE OUT AN ISOLD TORNADO GIVEN INTENSIFYING FRONTAL BOUNDARY EAST
OF THE BLKHLS. HEAVY RAIN ALSO A THREAT...ESPECIALLY ACROSS NWRN
SD NORTH OF THE WMFNT. ACTIVITY WILL QUICKLY SHIFT NORTH/EAST OF
THE CWFA THIS EVENING.

THURSDAY...UPPER LOW SHIFTS INTO THE NRN ROCKIES WITH SFC FRONT
PUSHING THROUGH OUR ERN ZONES. FAIRLY WDSPRD DIURNAL CONVECTION
EXPECTED...WITH A FEW SVR STORMS POSSIBLE ALONG THE SFC FRONT OVER
SCNTRL SD.

.LONG TERM...FRIDAY THROUGH TUESDAY
ISSUED AT 308 AM MDT WED MAY 27 2015

UPPER LEVEL TROF SHIFTS EAST OF THE NORTHERN PLAINS ON
FRIDAY AS SURFACE HIGH PRESSURE DROPS SOUTH OUT OF CANADA. LINGERING
SHOWERS ARE EXPECTED EARLY ON FRIDAY...SHIFTING SOUTH AND EAST EARLY
AS DRIER AIR MOVES IN. BY THE WEEKEND...COOL HIGH PRESSURE RESIDES
ACROSS THE NORTHERN PLAINS WITH BROAD UPPER LEVEL RIDGING DEVELOPING
LATE IN THE WEEKEND. A WARM UP IS EXPECTED THE FOLLOWING WEEK ALONG
WITH A RETURN OF SHOWERS AND THUNDERSTORMS.

&&

.AVIATION...FOR THE 12Z TAFS THROUGH 12Z THURSDAY MORNING
ISSUED AT 308 AM MDT WED MAY 27 2015

ISOLATED/SCATTERED -SHRA/-TSRA OVER SOUTHWEST SD WILL
SLOWLY SHIFT EAST ACROSS SOUTH CENTRAL SD EARLY THIS MORNING. VFR
CONDITIONS EXPECTED OUTSIDE OF PRECIPITATION...WITH MVFR CIGS/VSBYS
NEAR ANY STORMS.

&&

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

$$

SHORT TERM...JOHNSON
LONG TERM...15
AVIATION...15


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