Area Forecast Discussion
Issued by NWS Aberdeen, SD

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000
FXUS63 KABR 200854
AFDABR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ABERDEEN SD
354 AM CDT WED AUG 20 2014

.SHORT TERM...TODAY THROUGH THURSDAY

MAIN FOCUS FOR TODAY CENTERS AROUND THUNDERSTORM CHANCES THIS
AFTERNOON/EVENING AND POSSIBLE SEVERITY OF THEM. SVR PARAMETERS
STILL LOOKING GOOD...WITH AMPLE AMOUNTS OF INSTABILITY THIS
AFTERNOON THROUGH THIS EVENING...ALTHOUGH HIGHEST AMOUNTS ARE
ACROSS FSD CWA. NONETHELESS THOUGH...MODERATE INSTABILITY LIES
OVER OUR AREA. BULK SHEAR VALUES STILL OVER 40 KNOTS WITH LOW
LEVEL SHEAR EVEN LOOKING IMPRESSIVE AROUND 00Z. WILL BE WATCHING
CLOUD COVER TRENDS TODAY SINCE THIS WILL DETERMINE JUST HOW MUCH
SUNSHINE WILL BE ABLE TO HEAT THE ATMOSPHERE AND INCREASE THE
INSTABILITY. SPC HAS RAISED HAIL THREATS OVER THE CWA WHICH LOOKS
VERY REASONABLE GIVEN THE PARAMETERS. CANNOT RULE OUT A COUPLE
TORNADOES OVER THE AREA AS WELL GIVEN LOW LEVEL SHEAR PARAMETERS
AND LOW LCLS. CAM SOLUTIONS SHOWING CLUSTERS OF STORMS OR EVEN A
FEW SUPERCELLS OVER THE CWA LATE THIS AFTERNOON INTO THE EVENING.
SEEMS INITIATION WILL BE OVER CENTRAL SD LATE THIS AFTERNOON WITH
ACTIVITY PUSHING EAST INTO THE EVENING...WITH SOME UPSCALE GROWTH
QUITE POSSIBLE. HEAVY RAIN A THREAT WITH SOME OF THE STORMS AS
WELL GIVEN THE HIGH PWATS. INSERTED HEAVY RAIN MENTION INTO THE
GRIDS AS WELL AS T+ FOR SEVERE THREAT. PASSED ON ANY TYPE OF FLASH
FLOOD WATCH AT THIS POINT.

STORM SYSTEM EXITS THE AREA OVERNIGHT...WITH THURSDAY SHAPING UP
TO BE A DRY DAY WITH A WEST TO NORTHWEST BREEZE. STILL RATHER WARM
ALOFT BEHIND THIS SYSTEM...SO STILL FORECASTING RATHER WARM HIGHS
IN THE 80S.

.LONG TERM...THURSDAY NIGHT THROUGH TUESDAY

AN UPPER TROF OVER THE WESTERN CONUS WILL GRADUALLY TRANSITION
INTO THE NORTHERN PLAINS OVER THE COURSE OF THE EXTENDED PERIOD.
WHILE THIS FLOW IS INHERENTLY UNSTABLE...BEST CHANCES FOR
CONVECTION ARE ASSOCIATED WITH A SHORTWAVE FRIDAY/EARLY SATURDAY.
WHILE GREATEST INSTABILITY IS MODELED TO BE SOUTH OF THE
CWA...SPECIFIC HUMIDITY VALUES AT 850HPA TOPS OUT AROUND 14G/KG
AND 2 STANDARD DEVIATIONS ABOVE CLIMO...SO WILL CONTINUE TO SEE A
HEAVY RAIN THREAT GOING INTO THE WEEKEND. A SLOW MOVING FRONT WILL
PASS THROUGH THE REGION SUNDAY...WITH CANADIAN HIGH PRESSURE TO
FOLLOW. THE RESULT IS MUCH COOLER TEMPERATURES FOR NEXT WEEK.
MODELS DO BRING ANOTHER WAVE IN CLOSE TO THE END OF THE EXTENDED
PERIOD...WITH SURPRISINGLY DECENT PARALLELS BETWEEN THE GFS/ECMWF
DETERMINISTIC SOLUTIONS OUT TO 180 HOURS.

&&

.AVIATION...

06Z TAFS FOR THE KABR...KATY...KPIR AND KMBG TERMINALS

VFR CONDITIONS WILL PREVAIL ACROSS THE AREA OVERNIGHT AND THROUGH
MUCH OF THE DAY WEDNESDAY. SHOWERS AND THUNDERSTORMS WILL OCCUR
OVERNIGHT ACROSS THE SOUTHWESTERN PART OF THE CWA...THEN LOOK FOR
THEM TO SLOWLY SPREAD EASTWARD DURING THE DAY. SOME OF THE STORMS
MAY BECOME SEVERE DURING THE AFTERNOON AND EVENING...ESPECIALLY
ACROSS THE EASTERN CWA. CIGS AND VSBYS WILL LIKELY FALL INTO THE
MVFR CATEGORY WITH THE STRONGER THUNDERSTORM DEVELOPMENT.

&&

.ABR WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
MN...NONE.
&&

$$
SHORT TERM...TMT
LONG TERM...CONNELLY
AVIATION...CONNELLY

WEATHER.GOV/ABERDEEN




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