Area Forecast Discussion
Issued by NWS Rapid City, SD

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FXUS63 KUNR 070931
AFDUNR

AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
331 AM MDT THU MAY 7 2015

.SHORT TERM...TODAY THROUGH FRIDAY NIGHT
ISSUED AT 309 AM MDT THU MAY 7 2015

LATEST WV IMAGES SHOW UPPER LOW OVER NORTH CENTRAL SOUTH DAKOTA
MOVING NORTHEASTWARD. AT THE SURFACE...LOW PRESSURE WAS CENTERED
OVER EASTERN SOUTH DAKOTA. GUSTY NORTHWEST WINDS ARE LOCATED IN
THE TIGHT SFC PRESSURE GRADIENT TO THE WEST OF THE LOW OVER
WESTERN SOUTH DAKOTA. REGIONAL RADAR MOSAIC SHOWS SHOWERS OVER
WESTERN SOUTH DAKOTA ASSOCIATED WITH INSTABILITY DUE TO CAA ALOFT
AND CYCLONIC FLOW AROUND THE UPPER LOW. HAVE LOWERED POPS FOR
TODAY AS MODELS ARE IN GOOD AGREEMENT IN SHOWING THE LOW PRESSURE
SYSTEM MOVING QUICKLY OFF TO THE NORTHEAST WITH SHOWERS ENDING
OVER NERN WY THIS MORNING AND OVER MOST OF WRN SD EARLY THIS AFTN.
DRY AND COLD WEATHER IS EXPECTED TONIGHT WITH MANY AREAS OF
NORTHEASTERN WYOMING...THE BLACK HILLS AND NORTHWESTERN SOUTH
DAKOTA APPROACHING THE FREEZING MARK LATE TONIGHT/EARLY FRIDAY SO
FROST IS POSSIBLE IN THOSE AREAS OVERNIGHT. HIGH TEMPERATURES ON
FRIDAY WILL REMAIN AROUND 10 DEGREES COLDER THAN AVERAGE. A LOW
PRESSURE SYSTEM OVER THE SWRN CONUS WILL SPIN A SHORTWAVE TOWARD
THE FORECAST AREA ON FRIDAY SO HAVE INCLUDED LOW POPS OVER
NORTHEASTERN WYOMING...THE BLACK HILLS AND SOUTHWESTERN INTO SOUTH
CENTRAL SOUTH DAKOTA ON FRIDAY. THE PROBABILITY OF PRECIP WILL
INCREASE ACROSS MOST OF THE FORECAST AREA ON FRIDAY NIGHT AS THE
LOW PRESSURE SYSTEM STRENGTHENS.

.LONG TERM...SATURDAY THROUGH WEDNESDAY
ISSUED AT 309 AM MDT THU MAY 7 2015

UPPER LOW OVER THE FOUR CORNERS AREA WILL SWEEP NORTHEASTWARD
INTO THE CENTRAL PLAINS THIS WEEKEND...BRINGING MORE PRECIPITATION
TO THE REGION. AN AREA OF STRONG ISENTROPIC LIFT/FROTOGENESIS/Q-VECTOR
CONVERGENCE MOVES OVER THE REGION SATURDAY INTO SUNDAY...WITH THE
BEST FORCING ACROSS NEBRASKA. MODELS ARE CONSISTENT IN WRAPPING
COOLER AIR AROUND THE LOW INTO NORTHEAST WY/WESTERN SD...WITH
850MB TEMPS SLIGHTLY BELOW FREEZING. THIS WILL RESULT IN SOME OF
THE PRECIP FALLING AS SNOW...ESPECIALLY ACROSS THE HIGHER
ELEVATIONS...NORTHEAST WY...AND FAR SOUTHWESTERN SD.
HOWEVER...MUCH UNCERTAINTY EXISTS WITH THE TRACK OF THIS
STORM...HOW MUCH PRECIP WILL FALL AS SNOW...AND HOW MUCH SNOW WILL
ACTUALLY STICK.

PRECIP WILL GRADUALLY MOVE OUT OF THE AREA MONDAY...AND THEN MODELS
ARE HINTING AT A WEAK RIDGE BUILDING INTO THE REGION FOR EARLY NEXT
WEEK BRINGING A WARMING TREND AND DRIER WEATHER. TEMPERATURES THIS
WEEKEND WILL BE BELOW AVERAGE...WITH MORE SEASONABLE TEMPS RETURNING
BY THE MIDDLE OF NEXT WEEK.

&&

.AVIATION...FOR THE 12Z TAFS THROUGH 12Z FRIDAY MORNING
ISSUED AT 309 AM MDT THU MAY 7 2015

SHOWERS WILL GRADUALLY DISSIPATE THROUGHOUT THE DAY AS
DRIER AIR FILTERS INTO THE AREA. CIGS WILL BECOME VFR...WITH MVFR
CONDITIONS LINGERING LONGEST OVER CENTRAL SD. GUSTY NORTHWEST WINDS
ON THE SD PLAINS WILL CONTINUE THROUGH THIS AFTERNOON.

&&

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

$$

SHORT TERM...10
LONG TERM...POJORLIE
AVIATION...POJORLIE


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