Wednesday, August 17, 2011

MESO: Mesoscale Discussion 1996

ACUS11 KWNS 172243
SWOMCD
SPC MCD 172243
SDZ000-NEZ000-KSZ000-COZ000-172345-

MESOSCALE DISCUSSION 1996
NWS STORM PREDICTION CENTER NORMAN OK
0543 PM CDT WED AUG 17 2011

AREAS AFFECTED...PARTS OF SRN SD...WRN NEB...WRN KS AND ERN CO

CONCERNING...SEVERE THUNDERSTORM WATCH 783...

VALID 172243Z - 172345Z

THE SEVERE WEATHER THREAT FOR SEVERE THUNDERSTORM WATCH 783
CONTINUES.

POTENTIAL FOR SEVERE STORMS APPEARS TO BE INCREASING LATE THIS
AFTERNOON ACROSS SWRN-S CENTRAL SD...PART OF WRN NEB INTO FAR NERN
CO. PER REGIONAL RADAR IMAGERY...COUPLE OF STORMS HAVE TENDED TO
MAINTAIN INTENSITY /OVER CHERRY AND DEUEL COUNTIES NEB/. GIVEN
CURRENT RADAR TRENDS AND THE NRN EXTENT OF STRONG INSTABILITY/40-50
KT EFFECTIVE SHEAR INTO NRN/CENTRAL SD...A NEW WW MAY BE NEEDED TO
INCLUDE MORE OF CENTRAL/SOUTH CENTRAL SD.

...SD AND NEB...
SURFACE ANALYSIS AND STREAMLINE ANALYSES SHOWED A WIND SHIFT/ZONE OF
CONFLUENCE EXTENDING FROM ERN CO /EL PASO COUNTY/ NEWD THROUGH NERN
CO TO WRN NEB /DEUEL TO CHERRY COUNTIES/ AND INTO SWRN-S CENTRAL SD.
REGIONAL RADAR IMAGERY INDICATED STORMS HAVE BEEN DEVELOPING INVOF
THIS SSW-NNE ORIENTED SURFACE BOUNDARY...WITH STRONGEST AND MORE
ROBUST UPDRAFTS LOCATED ACROSS WRN NEB INTO SRN SD. THIS ACTIVITY
IS LOCATED WITHIN A CORRIDOR OF STRONGER MID-UPPER LEVEL WLY FLOW
AND JUST DOWNSTREAM OF AN APPARENT MIDLEVEL IMPULSE /PER RUC
ANALYSIS/ ADVANCING ESEWD INTO WRN SD/NEB. SELY LOW LEVEL WINDS
ALONG AND E OF THE SURFACE BOUNDARY WILL CONTINUE TO PROVIDE A FEED
OF MOIST/MODERATELY UNSTABLE AIR INTO THE DEVELOPING STORMS. THIS
COMBINED WITH EFFECTIVE BULK SHEAR OF 45-55 KT WILL SUPPORT
ORGANIZED SEVERE STORMS.

...ERN CO...
FARTHER S ACROSS ERN CO...TRENDS IN REGIONAL RADAR IMAGERY INDICATED
STORMS HAVE BEEN STRUGGLING TO MAINTAIN ROBUST UPDRAFTS. THIS MAY
BE DUE TO SOME INCREASE IN CAPPING PER OBJECTIVE ANALYSES INDICATING
WAA PER WLY MIDLEVEL WINDS IN THE 700-500 MB LAYER ESPECIALLY OVER
NERN CO. THUS...STORM COVERAGE MAY BE MORE ISOLATED DUE TO THE
CAPPING ISSUES ACROSS MUCH OF ERN CO /WITHIN WW 783 AND SWD INTO
SERN CO/ WHERE A MODERATELY UNSTABLE AIR MASS AND EFFECTIVE BULK
SHEAR OF 40-50 KT SUPPORT STORM ORGANIZATION.

..PETERS.. 08/17/2011

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

ATTN...WFO...FSD...ABR...GID...LBF...DDC...UNR...GLD...PUB...
BOU...CYS...

LAT...LON 44600117 44609957 43519943 41909979 40910006 38680018
37720128 37010202 37050361 37030429 37800472 38550503
38860504 39300410 39620372 40950348 41210266 43050286
43200232 44660211 44600117

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