Area Forecast Discussion
Issued by NWS Aberdeen, SD

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000
FXUS63 KABR 301549 AAA
AFDABR

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE ABERDEEN SD
1049 AM CDT TUE SEP 30 2014

.UPDATE...
STRONG UPPER LEVEL LOW PRESSURE CIRCULATION AND ITS ASSOCIATED 993
MB SURFACE LOW PRESSURE AREA WERE IN WESTERN SD THIS MORNING.
THESE WILL SLOWLY LIFT NORTHWARD THROUGH THE AFTERNOON AND NIGHT
AND BE IN SOUTHERN CANADA BY WEDNESDAY MORNING. A STRONG WAA BAND
OF SHOWERS WILL CONTINUE TO LIFT NORTH AND EAST THROUGH THE
EASTERN CWA INTO THE EARLY AFTERNOON. THE ISSUE FOR THE REST OF
THE DAY AND EVENING WILL BE THE MOVEMENT OF THE DRY SLOT AND
DISSIPATION OF CLOUD COVER INTO THE AFTERNOON. WITH SUNSHINE IN
THE DRY SLOT AND SURFACE HEATING...DO EXPECT SOME WEAK INSTABILITY
TO BUILD UP THIS AFTERNOON WITH THE DEVELOPMENT OF SOME THUNDERSTORMS.
SEVERAL HI-RES MODELS SHOW MORE SHOWER/STORM DEVELOPMENT THIS
AFTERNOON AND EARLY EVENING LIFTING NORTHEAST ACROSS THE REGION.
WITH A HIGH SHEAR ENVIRONMENT...SEVERAL STORMS SHOULD ROTATE AND
COULD PRODUCE SEVERE WEATHER ALONG WITH THE POSSIBILITY OF A
TORNADO. STILL HAVE THE SLIGHT RISK OF SEVERE WEATHER ACROSS MUCH
OF THE EASTERN CWA TODAY.


&&
.PREVIOUS DISCUSSION...
.SHORT TERM...TODAY THROUGH THURSDAY
A POWERFUL SURFACE LOW PRESSURE SYSTEM CURRENTLY OVER THE
PANHANDLE OF NEBRASKA WILL IMPACT THIS CWA THROUGH LATE THIS
AFTERNOON. THIS DEEPENING LOW PRESSURE SYSTEM WILL BRING STRONG
WINDS TO MOST OF THE CWA...WITH THE HIGHEST SUSTAINED WINDS
OCCURRING OVER CENTRAL SOUTH DAKOTA. BUFFER SOUNDING AT KPIR
INDICATE SUSTAINED WINDS AROUND 20-25 KNOTS...WITH A PEAK GUST OF
45 KNOTS. THUS A WIND ADVISORY HAS BEEN ISSUED FOR CENTRAL SD.

THE PREVIOUS FORECAST WAS WORRIED ABOUT THE EXTENT OF CLOUD COVER
THIS AFTERNOON POTENTIALLY LIMITING SEVERE WEATHER. THE CURRENT
WATER VAPOR IMAGERY SUGGEST THERE WILL BE BREAKS IN THE CLOUDS
TODAY. ONE UPPER LEVEL SHORT WAVE IS WRAPPING INTO THE LOW PRESSURE
SYSTEM WITH A NOTICEABLE DRY SLOT OVER WESTERN NEBRASKA. A
SECONDARY SHORT WAVE CURRENTLY OVER SOUTHERN COLORADO SHOULD
ROTATE INTO CENTRAL SOUTH DAKOTA LATER TODAY. BREAKS IN THE CLOUD
COVER WILL ALLOW FOR DESTABILIZATION TO OCCUR WITHIN A NARROW
CORRIDOR OF WEAK INSTABILITY BUT EXCELLENT SHEAR TO RESULT IN LOW
TOPPED SUPERCELLS. 0-1 KM BULK SHEAR VALUES EXCEEDING 30 KNOTS AND
0-1 KM ENERGY HELICITY INDEX OVER 2 SUGGEST TORNADOES WILL BE
POSSIBLE. THUS WILL MENTION SEVERE IN THE EASTERN HALF OF THE CWA
FOR THIS AFTERNOON.

THIS SYSTEM SHOULD PUSH NORTH OF THE CWA LATER THIS EVENING WITH
MOSTLY DRY CONDITIONS EXPECTED UNTIL THURSDAY. AN UPPER LEVEL
TROUGH MOVING ACROSS THE REGION ON THURSDAY WILL HAVE THE
POTENTIAL TO BRING SHOWERS TO THE EASTERN CWA DURING THE
AFTERNOON HOURS.

.LONG TERM...THURSDAY NIGHT THROUGH MONDAY
MEDIUM RANGE MODELS ARE INDICATING A LONGWAVE TROUGH TO PUSH
THROUGH THE NORTHERN PLAINS THURSDAY NIGHT. THE ECWMF IS THE MUCH
STRONGER MODEL WITH WINDS AND MUCH MORE ROBUST WITH ANY PRECIP.
HOWEVER...THE GFS AND CANADIAN ARE MUCH DRIER. WILL RAMP UP WINDS
FOR FRIDAY AND LEAVE POPS AS IS...BUT PRECIP CHANCES WILL HAVE TO
BE RAMPED UP ON FUTURE SHIFTS IF MODELS COME AROUND TO WET ECWMF.
COOL AIRMASS ON SATURDAY WILL BRING A CHANCE OF FROST TO MOST OF
THE AREA...SPLY ALONG AND EAST OF THE JAMES RIVER VALLEY.
NORTHWEST FLOW WILL CONTINUE THROUGH THE WEEKEND WITH WARMER AIR
RETURNING SATURDAY AFTERNOON THROUGH MONDAY. ANY FAST MOVING
SHORTWAVES LOOK TO BE ON THE WEAK SIDE ATTM.



&&

.AVIATION...
12Z TAFS FOR THE KABR...KATY...KPIR AND KMBG TERMINALS
SHOWERS AND A FEW THUNDERSTORMS WILL SPREAD ACROSS CENTRAL AND
EASTERN SOUTH DAKOTA THROUGH THE DAY. MVFR WITH LCL IFR CIGS ARE
POSSIBLE. ISOLATED SEVERE STORMS ARE POSSIBLE NEAR KMBG AND KABR
LATE THIS AFTERNOON. STRONG SOUTHEAST WINDS OF 15 TO 30KTS WILL
CONTINUE MOST OF DAY. THE STORM SYSTEM WILL EXIT RAPIDLY THIS
EVENING WITH IMPROVING CONDITIONS THIS EVENING.




&&

.ABR WATCHES/WARNINGS/ADVISORIES...
SD...WIND ADVISORY UNTIL 7 PM CDT /6 PM MDT/ THIS EVENING FOR HUGHES-
     JONES-LYMAN-STANLEY-SULLY.

MN...NONE.
&&

$$
UPDATE...MOHR
SHORT TERM...SD
LONG TERM...SCARLETT
AVIATION...SCARLETT

WEATHER.GOV/ABERDEEN





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