Area Forecast Discussion
Issued by NWS Rapid City, SD

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000
FXUS63 KUNR 301732
AFDUNR

AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
1132 AM MDT TUE SEP 30 2014

.UPDATE...
ISSUED AT 1109 AM MDT TUE SEP 30 2014

MADE SOME ADJUSTMENTS TO THE FLOOD HEADLINES. SEE THE HYDROLOGY
SECTION BELOW.

&&

.SHORT TERM...TODAY THROUGH WEDNESDAY NIGHT
ISSUED AT 236 AM MDT TUE SEP 30 2014

08Z SURFACE ANALYSIS HAD LOW BETWEEN KAIA/KCDR/KIEN. UPPER LOW
NOW STACKED ON TOP OF SURFACE LOW PER WATER VAPOR. FORCING AHEAD
OF SYSTEM PRONOUNCED WITH CONVECTION FIRING ALONG WARM FRONT FROM
LOW INTO CENTRAL SD. CONVECTION FEEDING STRONG DEFORMATION ZONE
FROM SOUTHWEST ND THROUGH THE BLACK HILLS INTO THE NE PANHANDLE.
00Z NAM A BIT FURTHER EAST WITH HEAVIEST BAND OF PRECIPITATION
THIS MORNING AND THE 00Z GFS FARTHEST WEST. SPLIT THE DIFFERENCE
AND YOU END UP WITH THE BEST RAINS OCCURRING IN THE CURRENT FLOOD
WATCH AREA. HEAVIEST RAIN SHOULD FALL THIS MORNING AS LOW LEVEL
UPSLOPE FEEDS INTO STRONG SYNOPTIC LIFT/DEFORMATION ZONE. AS LOW
PASSES...RAPID SHIFT TO WEST/NORTHWEST WINDS EXPECTED AND WELL-
DEFINED ISALLOBARIC FORCING. COLD AIR ADVECTION NOT THAT
STRONG...BUT SUBSIDENCE/PRESSURE RISES BEHIND LOW SHOULD BE
SUFFICIENT FOR A PERIOD OF ADVISORY CRITERIA WINDS FROM WEST
CENTRAL/SOUTHWEST INTO SOUTH CENTRAL SD TODAY. TEMPERATURES WILL
BE ALL OVER THE PLACE...BUT LIKELY LOWER THAN GUIDANCE OVER
CENTRAL PORTIONS OF THE CWA.

TONIGHT...STACKED SYSTEM RACES INTO SOUTHERN SK/MB AS IT WEAKENS.
CYCLONIC FLOW WILL SUPPORT SOME -SHRA OVER THE CWA. TEMPERATURES
WILL BE NEAR GUIDANCE.

WEDNESDAY...SECONDARY UPPER TROUGH SLICES THROUGH THE REGION WITH
BEST FORCING ACROSS SOUTHERN PORTIONS OF THE CWA AND THUS HAVE
PAINTED BETTER POPS TOWARD THE SD/NE BORDER. TEMPERATURES WILL BE
NEAR GUIDANCE.

&&

.LONG TERM...THURSDAY THROUGH MONDAY
ISSUED AT 236 AM MDT TUE SEP 30 2014

CYCLONIC FLOW WILL CONTINUE OVER THE REGION THURSDAY. A STRONG
UPPER WAVE IS PROGGED TO DIVE DOWN THE BACKSIDE OF THE TROUGH
THURSDAY AND THURSDAY NIGHT...BRINGING A STRONG COLD FRONT TO THE
AREA. GUSTY NW WINDS ARE EXPECTED BEHIND THE FRONT AS A TIGHT
PRESSURE GRADIENT DEVELOPS. ISOLATED SHOWERS WILL BE POSSIBLE WITH
THE FROPA. HIGH PRESSURE WILL QUICKLY BUILD IN WITH UPPER RIDGING
DEVELOPING ACROSS THE WESTERN CONUS. DRY WEATHER IS EXPECTED
THROUGH THE END OF THIS WEEK INTO EARLY NEXT WEEK. TEMPS WILL BE
COOLER THAN AVERAGE THU/FRI...THEN WARM BACK TO SEASONAL AVERAGES
BY THE WEEKEND.

&&

.AVIATION...FOR THE 18Z TAFS THROUGH 18Z WEDNESDAY
ISSUED AT 1136 AM MDT TUE SEP 30 2014

STORM SYSTEM NR KPHP MOVG NEWD...W/ WIDESPREAD SHWRS...ISOLD
TSTMS...AND MVFR CIGS/VSBY...ESP OVR WRN SD THIS AFTN. GUSTY
NORTHWEST WINDS WL INCRS OVER NERN WY/SWRN INTO S CNTRL SD THIS
AFTN. CIGS WL IMPROVE THIS EVNG...WHILE WNDS DIMINISH AND BCM
WESTERLY.

&&

.HYDROLOGY...
ISSUED AT 1109 AM MDT TUE SEP 30 2014

THE LOW PRESSURE CENTER CURRENTLY LOCATED OVER HAAKON COUNTY WILL
CONTINUE TO ACCELERATE OFF TOWARD THE NORTHEAST THIS AFTERNOON.
BANDS OF SHOWERS WILL CONTINUE OVER MUCH OF THE FORECAST AREA
THROUGH THE AFTERNOON BUT WILL SHIFT NORTHEASTWARD AS WELL. THE
FLOOD WATCH THAT WAS IN EFFECT FOR PARTS OF NORTHEASTERN WYOMING
AND WESTERN SOUTH DAKOTA WAS SET TO EXPIRE AT NOON. ALTHOUGH RAIN
SHOWERS WILL CONTINUE TO BE FOUND OVER THE AREA...IT LOOKS LIKE
THE THREAT OF WIDESPREAD HEAVY RAIN IS ENDING...SO HAVE CANCELLED
THAT FLOOD WATCH. A FLOOD ADVISORY REMAINS IN EFFECT FOR FALL
RIVER COUNTY AND PARTS OF CUSTER...WESTERN PENNINGTON AND FAR
WESTERN SHANNON COUNTIES UNTIL 700 PM MDT THIS EVENING. THOSE ARE
THE AREAS WHICH RECEIVED THE MOST RAIN OVER THE PAST COUPLE OF
DAYS. SMALL CREEKS AND STREAMS ARE RUNNING VERY HIGH IN THOSE
AREAS. DEBRIS IN THOSE STREAMS CAN QUICKLY BLOCK CULVERTS WHICH
COULD CAUSE MINOR FLOODING.

&&

.UNR WATCHES/WARNINGS/ADVISORIES...
SD...WIND ADVISORY UNTIL 6 PM MDT /7 PM CDT/ THIS EVENING FOR SDZ026-
     027-030>032-041>044-046-047-049-072>074.

WY...NONE.
&&

$$

UPDATE...10
SHORT TERM...HELGESON
LONG TERM...13
AVIATION...13
HYDROLOGY...10





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