Area Forecast Discussion
Issued by NWS Rapid City, SD

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000
FXUS63 KUNR 281049
AFDUNR

AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
449 AM MDT SUN SEP 28 2014

.SHORT TERM...TODAY THROUGH MONDAY NIGHT
ISSUED AT 256 AM MDT SUN SEP 28 2014

08Z SURFACE ANALYSIS HAD A STATIONARY FRONTAL BOUNDARY FROM
NORTHWEST MN TO KIEN TO CENTRAL CO. NORTHERLY WINDS BEHIND
BOUNDARY BRINGING MODEST COLD AIR ADVECTION TO THE CWA ALONG WITH
SOME ST GIVEN SLIGHT NORTHEASTERLY/UPSLOPE COMPONENT TO
INCREASINGLY MOIST BOUNDARY LAYER FLOW. ST WILL PLAY A BIG ROLE IN
TEMPERATURES TODAY WITH LATEST GUIDANCE SUGGESTING A SURGE
SOUTHWARD WRAPPING AROUND THE BLACK HILLS TO THE NE BORDER. HAVE
ADJUSTED TEMPERATURES DOWNWARD 5-10F FOR THESE AREAS BEHIND COOL
FRONT. UPPER LOW SPINNING OVER NV PER WATER VAPOUR WILL MOVE
NORTHEAST TODAY SOME WITH FORCING AHEAD OF SYSTEM SLOWLY MOVING
INTO EASTERN WY/FAR WESTERN SD. RESULT WILL BE A SLOW INCREASE IN
CHANCE POPS THROUGH THIS AFTERNOON.

TONIGHT/MONDAY...UPPER LOW EJECTS INTO THE NORTHERN PLAINS SPINNING
OVER WESTERN SD BY 12Z TUESDAY AND BECOMING NEGATIVELY TILTED.
SIGNIFICANT MOISTURE ADVECTS NORTHWARD AHEAD OF LOW EVIDENCED BY
WELL-DEFINED 850-700MB THETA-E ADVECTION. MODERATE/STRONG
ISENTROPIC LIFT DEVELOPS AHEAD OF LOW WITH NORTH/SOUTH ORIENTED
BAND OF FRONTOGENESIS CENTERED OVER THE CWA. SCENARIO PORTENDS
SOAKING RAINS OVER THE CWA...CENTERED ON/NEAR THE BLACK HILLS.
POPS/QPF REFLECT WET THINKING. AS SURFACE LOW RIDES UP COOL FRONT
MONDAY AFTERNOON/EVENING...A NARROW BAND OF 500-1000J/KG SBCAPE
DEVELOPS WITH SUFFICIENT 0-6KM BULK SHEAR FOR ISOLATED SEVERE
THUNDERSTORMS SOUTHWEST INTO SOUTH CENTRAL SD. TEMPERATURES WILL
SHOW A SHARP GRADIENT ACROSS THE CWA AGAIN.

&&

.LONG TERM...TUESDAY THROUGH SATURDAY
ISSUED AT 256 AM MDT SUN SEP 28 2014

SHOWERS WILL CONTINUE THRU TUESDAY WITH WRAP-AROUND PRECIP
ASSOCIATED WITH THE NEGATIVELY TILTED UPPER LOW. THIS PRECIP WILL
SLOWLY EXIT THE AREA INTO TUESDAY NIGHT AS THE LOW LIFTS INTO ND.
IT APPEARS THAT MANY AREAS COULD SEE OVER AN INCH OF RAIN BY
TUESDAY EVNG. COOLER TEMPS PUSHING INTO THE AREA BEHIND THE SYSTEM
WILL KEEP TEMPERATURES WELL BELOW SEASONAL AVERAGES. CYCLONIC FLOW
REMAINING OVER THE REGION WILL KEEP LOW CHANCE POPS OVER THE AREA
WEDNESDAY THROUGH THURSDAY. SHSN POSSIBLE IN THE BLKHLS BOTH THU
AND FRI MORNINGS. GFS/ECMWF CONTINUE TO SHOW UPPER RIDGING OVER
THE WRN CONUS HEADING INTO NEXT WEEKEND...SUGGESTING DRIER WEATHER
AND NEAR AVERAGE TEMPS.

&&

.AVIATION...FOR THE 12Z TAFS THROUGH 12Z MONDAY MORNING
ISSUED AT 449 AM MDT SUN SEP 28 2014

MVFR CIGS HAVE MADE IT INTO PORTIONS OF NE WY TO NW
SD/NRN BLKHLS. THESE CIGS WILL CONTINUE TODAY INTO TONIGHT. PRECIP
WILL DEVELOP THROUGH THE DAY OVER NE WY THRU FAR WRN SD...AND SPREAD
EWD THRU TONIGHT. MVFR CIGS WILL DROP TO IFR LATE TODAY INTO
TONIGHT.

&&

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

$$

SHORT TERM...HELGESON
LONG TERM...13
AVIATION...13







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