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000
FXUS63 KABR 181956
AFDABR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ABERDEEN SD
256 PM CDT SAT MAY 18 2013

.SHORT TERM...TONIGHT AND TOMORROW
FORECAST CHALLENGES INCLUDE SEVERE WEATHER POTENTIAL THIS
AFTERNOON THROUGH TONIGHT...ALONG WITH HEAVY RAINFALL/FLASH
FLOODING POTENTIAL THIS AFTERNOON THROUGH TOMORROW.

CURRENTLY...ENERGY ASSOCIATED WITH A STRONG UPPER LEVEL LONG-WAVE
TROF IS BEGINNING TO INFLUENCE THE REGION WITH ITS LARGE SCALE
ASCENT/UVM. ALREADY NOTING CONVECTION FIRING OFF THE BLACK
HILLS...WITH ADDITIONAL CONVECTIVE CELLS TRYING TO INITIATE ALONG
WHAT APPEARS TO BE A DEVELOPING DRYLINE/INVERTED SURFACE TROF
SLOWLY WORKING NORTHWEST BETWEEN PINE RIDGE AND PHILIP. WILL ALSO
BE WATCHING FOR STORMS TO FIRE WITHIN THIS INVERTED SURFACE TROF
/ORIENTED ROUGHLY FROM PIERRE TO JAMESTOWN/ OVER THIS CWA LATER
THIS EVENING. WITH CONVECTIVE DEBRIS CLOUDS VACATING THE REGION
THIS AFTERNOON AND NO LOW STRATUS BENEATH IT TO HAVE TO
ERODE...TEMPERATURES ARE BEGINNING THEIR CLIMB THROUGH THE MID AND
UPPER 70S INTO THE 80S OVER MUCH OF THE CWA ON RELATIVELY LIGHT
AND VARIABLE WINDS. AT 19Z...MLCAPE VALUES ACROSS THE SOUTHWESTERN
ZONES WAS 1500-2000J/KG WITH NO APPRECIABLE MLCIN CAPPING THE
ATMOSPHERE.

LATE THIS AFTERNOON THROUGH LATE TONIGHT...WITH THE ENVIRONMENT
OVER MUCH OF THIS CWA EXPECTED TO MAINTAIN AN ADEQUATE
INSTABILITY/LOW SHEAR PROFILE...STORM MODE IS EXPECTED TO BE
MAINLY PULSE TO PERHAPS MULTICELLULAR. COULD SEE A FEW CLUSTERS OF
STORMS ORGANIZE INTO SMALL BOWING SECTIONS IF A BALANCE BETWEEN
COLD POOL/SHEAR INTERACTION CAN BE ACHIEVED...WHICH WOULD
PROMOTE SOME STRONG WIND GUSTS. OTHERWISE...PROBABLY DEALING
MAINLY WITH MARGINALLY SEVERE HAIL FROM LATE THIS AFTERNOON
THROUGH LATE TONIGHT. ONE OTHER GROWING CONCERN IS OVER STORM
MOTION. IF STORMS DEVELOP WITHIN THIS INVERTED SURFACE TROF...THEY
ARE NOT GOING TO MOVE ALL THAT MUCH OR ALL THAT FAST. THE SIGNAL
SHOWING UP IN QUITE A NUMBER OF CAM SOLUTIONS FROM
YESTERDAY...LAST NIGHT AND TODAY IS THAT SOME AREAS COULD END UP
UNDERNEATH OF BLANKET OF MODERATE TO HEAVY RAINFALL FOR SEVERAL
HOURS IN A ROW BEFORE SYNOPTIC SCALE FORCING FINALLY BEGINS TO
PUSH-BROOM EVERYTHING OFF TO THE NORTHEAST LATE TONIGHT. PWATS ARE
WELL OVER AN INCH...IN SOME AREAS OVER 1.25 INCHES. AND DESPITE
THE SOIL/SUB-SOIL LIKELY BEING ABLE TO HANDLE QUITE A BIT OF
PRECIPITATION...THERE ARE A FEW AREAS ACROSS THE CWA WHERE GRIDDED
FLASH FLOOD GUIDANCE VALUES IN 6 HOURS ARE LESS THAN 3 INCHES.
ISOLATED FLASH FLOODING TONIGHT IS CERTAINLY NOT OUT OF THE
QUESTION. FOR THIS AFTERNOON THROUGH LATE TONIGHT HAVE SEVERE
THUNDER AND HEAVY RAINFALL MENTION IN THE GRIDS PROGRESSING FROM
WEST TO EAST.


.LONG TERM...SUNDAY NIGHT THROUGH SATURDAY

SEVERE WEATHER THREAT BEGINS TO DIMINISH RAPIDLY WITH SUNSET DUE
TO LACK OF LOW LEVEL JET ENHANCEMENT AND THE RESPONSIBLE SHORTWAVE
LIFTS NORTH AND BEGINS TO PIVOT AROUND OUR UPPER LOW. THE UPPER
LOW WILL CONTINUE TO SIT AND SPIN OVER THE REGION MONDAY...WITH
NEAR SATURATED SOUNDINGS. ANY DAYTIME HEATING/FILTERED SUN WILL
ACT TO DESTABILIZE THE ATMOSPHERE AND PROVIDE US WITH WEAK
THUNDERSTORMS. THE ENVIRONMENT WILL BE DEFINED BY SKINNY CAPE
BETWEEN 500 AND 1500 J/KG WITH WEAK WINDS ALOFT. THUS...BEING FED
BY DAYTIME HEATING AND LIMITED DYNAMICS ALOFT...EXPECT WIDESPREAD
STORMS TO BEGIN DISSIPATING BY MID/LATE AFTERNOON AS OUTFLOWS/COLD
POOLS STABILIZE THE LOWER LAYERS. MOIST SOUNDINGS PERSIST INTO
TUESDAY AND PART OF WEDNESDAY AS UPPER LOW REMAINS OVER THE
AREA...AND THANKS TO ISENTROPIC FORCING/TROWAL TYPE FEATURE...WILL
CONTINUE SHOWER MENTION INTO THESE DAYS. WEAK INDUCED RIDGING/COL
REGION MOVES OVERHEAD FOR THE LATTER HALF OF THE WORK WEEK...FOR
DRY CONDITIONS AND TEMPERATURES NEAR CLIMO. THE NEXT UPPER SYSTEM
WILL SLOWLY MAKE ITS WAY ACROSS THE NORTHERN ROCKIES FOR NEXT
WEEK. THIS STILL APPEARS TO BE TOO FAR WEST TO HAVE AN APPRECIABLE
AFFECT ON THE FORECAST AREA...ASIDE FROM RETURN FLOW AND WARM
ADVECTION PUSHING H85 TEMPERATURES INTO THE MID TEENS
CELSIUS...AND THUS TEMPERATURES AT OR ABOVE CLIMO.


&&

.AVIATION...
18Z TAFS FOR THE KABR...KATY...KPIR AND KMBG TERMINALS

GOOD VFR SHOULD BE THE RULE OF THE DAY AND RIGHT ON INTO
TONIGHT...UNTIL SHOWERS AND THUNDERSTORMS DEVELOP AND MOVE THROUGH
THE FORECAST AREA. PRESENTLY SOME FORM OF VICINITY SHOWER OR
VICINITY THUNDERSTORM MENTION IS IN ALL FOUR TAFS FOR WHEN THE
HIGHEST PROBABILITY OF PRECIPITATION IS CURRENTLY ANTICIPATED.
EXPECT SUB-VFR VISBY/CIG CONDITIONS IN MODERATE TO HEAVY RAINFALL
TO ACCOMPANY SHOWERS AND STORMS OVERNIGHT. THERE COULD ALSO BE
SOME HAIL AND STRONG WINDS TO DEAL WITH TONIGHT. BEHIND THE
PRECIPITATION...SUB-VFR BKN/OVC STRATUS IS EXPECTED TO FORM AND
STAY PUT LATE TONIGHT INTO THE MORNING HOURS ON SUNDAY.


&&

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

$$
SHORT TERM...DORN
LONG TERM...CONNELLY
AVIATION...DORN

WEATHER.GOV/ABERDEEN