MESO: Mesoscale Discussion 1242

ACUS11 KWNS 212040
SWOMCD
SPC MCD 212040
NEZ000-SDZ000-KSZ000-COZ000-212215-

MESOSCALE DISCUSSION 1242
NWS STORM PREDICTION CENTER NORMAN OK
0340 PM CDT THU JUN 21 2007

AREAS AFFECTED...NERN CO....SWRN/CNTRL NEB

CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE

VALID 212040Z - 212215Z

TSTMS HAVE DEVELOPED WITHIN A HOT/DEEPLY MIXED AIR MASS ALONG A
QUASI-STATIONARY FRONT AND ASSOCIATED MESOLOW IN NERN CO. TO THE NE
OF THIS ACTIVITY...A VERY UNSTABLE AIR MASS EXISTS ACROSS CNTRL NEB
BENEATH A WEAKENING CAP. IF STORMS CAN INITIATE FARTHER
NEWD...SUPERCELLS WOULD BE LIKELY. THIS AREA WILL BE MONITORED FOR A
POSSIBLE WW.

A FEW TSTMS DEVELOPED OVER THE PAST HOUR JUST SE OF THE I-76
CORRIDOR FROM SERN MORGAN COUNTY TO SRN SEDGWICK COUNTY ALONG A
QUASI-STATIONARY FRONT. THIS BOUNDARY ARCED N/NEWD ACROSS WRN CHERRY
CO NEB. ALL OF THE CONVECTION REMAINS W OF THE DRY LINE WHICH
EXTENDS FROM NEAR HOOKER COUNTY NEB SWD THROUGH THOMAS COUNTY KS.
ALTHOUGH TOTAL INSTABILITY IS WEAK BEHIND THE DRY LINE...45 TO 55
DEGREE SURFACE DEW POINT DEPRESSIONS HAVE LED TO VERY STEEP
LOW-LEVEL LAPSE RATES. THIS WILL SUPPORT STRONG TO POSSIBLY SEVERE
OUTFLOW WINDS OVER THE NEXT FEW HOURS.

FARTHER NE...THE CAP IS WEAKENING E OF THE DRY LINE...HOWEVER LATEST
RUC OBJECTIVE ANALYSIS STILL INDICATES RATHER STRONG MLCIN. VIS
IMAGERY HAS ALSO SHOWN LIMITED CU DEVELOPMENT ALONG THE FRONT THUS
FAR IN THE WARM/MOIST SECTOR. GIVEN THAT THE AIR MASS IS VERY
UNSTABLE AND DEEP-LAYER SHEAR REMAINS AT LEAST MODERATE...A
CONDITIONAL SEVERE THREAT EXISTS SINCE ANY TSTMS THAT CAN DEVELOP
WOULD LIKELY BECOME RAPIDLY SUPERCELLULAR. A MORE PROBABLE SCENARIO
MAY BE FOR THE CONVECTION OVER NERN CO TO ORGANIZE AND EVENTUALLY
CROSS THE DRY LINE IN SWRN NEB DURING THE EARLY EVENING.

.GRAMS.. 06/21/2007

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

ATTN...WFO...LBF...UNR...GLD...BOU...CYS...

40530397 41340284 42350221 43020155 43150082 42460026
41710005 40170092 39740204 39610313 39910412 40410402

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