ACUS11 KWNS 221916
SWOMCD
SPC MCD 221916
NEZ000-KSZ000-COZ000-WYZ000-222045-
MESOSCALE DISCUSSION 1646
NWS STORM PREDICTION CENTER NORMAN OK
0216 PM CDT WED JUL 22 2009
AREAS AFFECTED...PORTIONS OF SERN WY...NERN CO INTO WRN/CNTRL NEB
AND WRN KS
CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE
VALID 221916Z - 222045Z
THE THREAT FOR ISOLATED SEVERE STORMS CAPABLE OF HAIL AND LOCALLY
DAMAGING WIND GUSTS WILL INCREASE THIS AFTERNOON INTO EVENING.
CONVECTIVE TRENDS ARE BEING MONITORED FOR A POSSIBLE WW.
18Z MESOANALYSIS INDICATES A WEAK PRESSURE GRADIENT OVER THE REGION
TODAY...THOUGH A WEAK BOUNDARY/CONVERGENCE ZONE HAS BECOME
BETTER-DEFINED IN VISIBLE SATELLITE AND OBSERVATIONS DATA OVER
NEB...GENERALLY ALONG A OFK-BBW-SNY LINE. A SMALL CLUSTER OF TSTMS
/LIKELY ELEVATED/ HAS PERSISTED ALONG THIS BOUNDARY TODAY OVER WRN
INTO CNTRL PARTS OF NEB WITH ADDITIONAL DEEPENING CUMULUS OBSERVED
TO THE W OVER THE SRN NEB PNHDL. THIS ACTIVITY APPEARS TO BE
ASSOCIATED WITH SHORT WAVE TROUGH DIGGING SEWD THROUGH WRN/CNTRL NEB
INTO NRN KS PER WATER VAPOR IMAGERY.
STRONGEST STORMS NEAR EAR AS OF 1850Z ARE LIKELY IN THE PROGRESS OF
BECOMING SURFACE-BASED. HOWEVER...ACTIVITY WILL CONTINUE TO
MOVE/DEVELOP SEWD INTO LOW-LEVEL RIDGE AXIS WHERE BOUNDARY LAYER
BECOMES PROGRESSIVELY MORE STABLE WITH SWD EXTENT. HOWEVER...ANY
STORMS THAT CAN DEVELOP ALONG BOUNDARY OVER THE NEB PNHDL INTO SWRN
NEB WILL MOVE SWD/SEWD INTO A RELATIVELY HIGH THETA-E AIR MASS IN
PLACE OVER ERN CO/WRN KS WHERE MLCAPE MAY APPROACH 1000-1500 J/KG
LATER THIS AFTERNOON. MOREOVER...ABOVE-MENTIONED SHORT WAVE TROUGH
IS BEING ACCOMPANIED BY A BELT OF MODEST /30-35 KT/ NWLY FLOW IN THE
MIDLEVELS...RESULTING IN 35-40 KT OF EFFECTIVE BULK SHEAR.
THUS...SETUP WILL BE FAVORABLE FOR ORGANIZED/ROTATING STORMS CAPABLE
OF HAIL/HIGH WINDS GIVEN SURFACE-BASED STORM INITIATION AND
SUSTENANCE.
FARTHER W OVER THE LARAMIE RANGE SWD ALONG THE CO FRONT
RANGE...CUMULUS IS GRADUALLY DEEPENING AS BOUNDARY LAYER WARMS
THROUGH THE 70S. AIR MASS IS DRIER ALONG THE CHEYENNE RIDGE...BUT
DEWPOINTS ARE LINGERING IN THE MID/UPPER 50S N OF THE PALMER DIVIDE.
AREA PROFILERS INDICATE THAT VERTICAL SHEAR TENDS TO DECREASE WITH
SWD EXTENT WITH THE GREATEST THREAT FOR A FEW ORGANIZED...SEVERE
STORMS LIKELY REMAINING CONFINED TO N OF PUB.
FINALLY...CUMULUS IS ALSO DEEPENING ALONG WEAK TROUGH/CONVERGENCE
ZONE /ORIENTED N-S/ ALONG THE CO/KS BORDER. SHOULD STORMS
DEVELOP...THE COMBINATION OF MODEST CONVECTIVE INSTABILITY AND
VERTICAL SHEAR INDICATE SOME THREAT FOR ISOLATED SEVERE STORMS.
..MEAD.. 07/22/2009
...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT...
ATTN...WFO...GID...LBF...DDC...GLD...PUB...BOU...CYS...
LAT...LON 39410588 40930644 41870657 42330641 42160607 41690486
41260428 41070349 41190237 41859994 41749922 40719881
40299951 38620105 37420140 37420238 39490257 40090358
40090419 39730449 39320471 38950518 38900573 39410588
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