Area Forecast Discussion
Issued by NWS Rapid City, SD

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000
FXUS63 KUNR 300842
AFDUNR

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

.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 VAPOUR. 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 06Z TAFS THROUGH 06Z TUESDAY NIGHT
ISSUED AT 236 AM MDT TUE SEP 30 2014

INTENSE AREA OF LOW PRESSURE WILL MOVE ACROSS SOUTHWEST SOUTH
DAKOTA TODAY...AND LIFT INTO NORTH CENTRAL SOUTH DAKOTA THIS
AFTERNOON. WIDESPREAD SHOWERS/THUNDERSTORMS OVER THE AREA
TODAY...WITH IFR CIGS/VSBY. GUSTY WEST-NORTHWEST WINDS WILL
DEVELOP OVER NORTHEAST WYOMING/FAR WESTERN SOUTH DAKOTA
TODAY...WHILE GUSTY SOUTH/SOUTHWEST WINDS DEVELOP OVER SOUTH
CENTRAL SOUTH DAKOTA. CONDITIONS WILL BEGIN TO IMPROVE FROM SOUTH
TO NORTH LATE THIS AFTERNOON INTO TONIGHT.

&&

.HYDROLOGY...
ISSUED AT 236 AM MDT TUE SEP 30 2014

STACKED UPPER LEVEL LOW PRESSURE SYSTEM WILL MOVE FROM THE NE
PANHANDLE INTO SOUTH CENTRAL CANADA THROUGH TONIGHT. STRONG
DEFORMATION ZONE FORCING WILL CONTINUE TO PRODUCE A BAND OF
LOCALLY HEAVY RAIN FROM K2WX TO KCUT TO FAR SOUTHWEST SD THIS
MORNING. AN ADDITIONAL HALF INCH OF RAIN WILL FALL THIS MORNING
WITH LOCALLY HIGHER AMOUNTS. THE RESULT MAY BE MINOR FLOODING OF
CREEKS AND STREAMS. THE RAIN WILL TAPER OFF FROM SOUTH TO NORTH
THIS AFTERNOON.

&&

.UNR WATCHES/WARNINGS/ADVISORIES...
SD...FLOOD WATCH UNTIL NOON MDT TODAY FOR SDZ001-002-012-013-024>031-
     041-042-072>074.

     WIND ADVISORY FROM 8 AM THIS MORNING TO 6 PM MDT THIS EVENING
     FOR SDZ027-041>044.

     WIND ADVISORY FROM 10 AM MDT /11 AM CDT/ THIS MORNING TO 6 PM
     MDT /7 PM CDT/ THIS EVENING FOR SDZ032-046-047-049.

     WIND ADVISORY UNTIL 6 PM MDT THIS EVENING FOR SDZ026-030-031-
     072>074.

WY...FLOOD WATCH UNTIL NOON MDT TODAY FOR WYZ056-057-071.

&&

$$

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



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