Wednesday, September 2, 2009

MESO: Mesoscale Discussion 1987

ACUS11 KWNS 022133
SWOMCD
SPC MCD 022132
SDZ000-NEZ000-022300-

MESOSCALE DISCUSSION 1987
NWS STORM PREDICTION CENTER NORMAN OK
0432 PM CDT WED SEP 02 2009

AREAS AFFECTED...S CENTRAL AND SERN SD SWD INTO CENTRAL NEB

CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE

VALID 022132Z - 022300Z

LIMITED SEVERE THREAT WITH STORMS DEVELOPING S AND E OF THE SD UPPER
LOW MAY REQUIRE WW ISSUANCE.

UPPER LOW CONTINUES MOVING SLOWLY SEWD ACROSS CENTRAL SD...WITH A
BROKEN LINE OF STRONG STORMS CONTINUING TO DEVELOP S AND E OF THE
LOW. THE STRONGER CELLS EXTEND ATTM FROM SRN HAND COUNTY SD --
NEAR/JUST E OF THE CENTER OF CIRCULATION -- SSWWD INTO ROCK COUNTY
NEB -- WHERE LOW 60S BOUNDARY-LAYER DEWPOINTS COMBINED WITH DAYTIME
HEATING HAVE YIELDED 500 TO 1000 J/KG MIXED-LAYER CAPE.

WHILE DEEP-LAYER SHEAR IS NOT PARTICULARLY STRONG -- ON THE ORDER OF
25 KT PER AREA VWP/PROFILER DATA...VEERING FLOW WITH HEIGHT AND
AMBIENT VORTICITY ASSOCIATED WITH THE UPPER CIRCULATION CENTER IS
RESULTING IN LOW-LEVEL ROTATION WITH STRONGER CELLS. THUS...LIMITED
THREAT FOR ISOLATED/BRIEF TORNADOES APPEARS POSSIBLE...ALONG WITH
MARGINALLY-SEVERE HAIL AND/OR LOCALLY GUSTY WINDS. THOUGH THREAT
SHOULD REMAIN LIMITED TO A FEW OF THE STRONGEST CELLS...THE
POTENTIAL FOR THIS THREAT TO PERSIST INTO THE MID EVENING HOURS
SUGGESTS THAT A WW MAY BE NEEDED.

..GOSS.. 09/02/2009

...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT...

ATTN...WFO...FSD...OAX...ABR...GID...LBF...

LAT...LON 43209919 44469943 44179843 43369771 41469800 41189993
41949990 42809936 43209919

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