MESO: Mesoscale Discussion 0828

ACUS11 KWNS 201853
SWOMCD
SPC MCD 201852
KSZ000-NEZ000-OKZ000-202045-

MESOSCALE DISCUSSION 0828
NWS STORM PREDICTION CENTER NORMAN OK
0152 PM CDT FRI MAY 20 2011

AREAS AFFECTED...CNTRL KS...S-CNTRL NEB...NWRN OK

CONCERNING...SEVERE POTENTIAL...SEVERE THUNDERSTORM WATCH LIKELY

VALID 201852Z - 202045Z

CONTINUED DESTABILIZATION ALONG COLD FRONT WILL HELP FOSTER TSTM
DEVELOPMENT THIS AFTERNOON WITH PRIMARY INITIAL RISK OF SEVERE HAIL.
THE PROBABILITY OF A SEVERE TSTM WATCH BEING ISSUED BY 21Z IS 60
PERCENT.

18Z SUBJECTIVE SURFACE ANALYSIS PLACED A PAIR OF 1003 MB CYCLONES
NEAR RSL AND 30 NNW GAG ALONG A N/S-ORIENTED COLD FRONT FROM THE
CNTRL INTO THE SRN PLAINS. SURFACE HEATING HAS BECOME MORE ROBUST
DURING THE PAST COUPLE OF HOURS AS AN EXPANSIVE CIRRUS CANOPY
ASSOCIATED WITH A LARGE-SCALE MCS OVER THE ERN GREAT PLAINS HAS
GRADUALLY SHIFTED EWD. A NARROW AXIS OF A MARGINALLY UNSTABLE AIR
MASS WITH MLCAPE AROUND 500 J/KG HAS DEVELOPED IMMEDIATELY AHEAD OF
THE COLD FRONT WHERE SURFACE TEMPERATURES HAVE WARMED INTO THE
MIDDLE 70S.

SHOWERS/TSTMS HAVE RECENTLY COMMENCED ALONG THE FRONT FROM CNTRL KS
INTO W-CNTRL OK...AN HOUR OR TWO EARLIER THAN LATEST
CONVECTION-ALLOWING HRRR AND WRF-NMM/NSSL GUIDANCE. CONTINUED
DESTABILIZATION WILL SUPPORT INCREASINGLY BUOYANT UPDRAFTS THROUGH
THE AFTERNOON AMIDST STRONG DEEP-LAYER SPEED SHEAR.
HOWEVER...VEER-BACK-VEER WIND PROFILES INDICATED IN AREA
PROFILERS...ALONG WITH WEAK LOW-LEVEL FLOW AND DEEP-LAYER SHEAR
VECTORS ORIENTED NEARLY PARALLEL TO THE INITIATING BOUNDARY SHOULD
RESULT IN A MORE CLUSTER TYPE CONVECTIVE MODE AND SERVE TO TEMPER A
MORE WIDESPREAD LARGE HAIL THREAT.

..GRAMS.. 05/20/2011

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

ATTN...WFO...TOP...ICT...OUN...GID...DDC...

LAT...LON 37209980 38849927 40699918 41049909 41219865 41059823
40469798 38799791 36319878 36059918 36109971 36609990
37209980

+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-
To unsubscribe from WX-STORM send e-mail to LISTSERV@LISTSERV.ILLINOIS.EDU with
"unsub wx-storm" in the body of your message. For more information write cnovy@cox.net.