SPC MD 1663

MD 1663 CONCERNING SEVERE POTENTIAL...WATCH UNLIKELY FOR PORTIONS OF NORTHERN OKLAHOMA AND SOUTHERN KANSAS

MESOSCALE DISCUSSION 1663
NWS STORM PREDICTION CENTER NORMAN OK
0327 PM CDT THU SEP 08 2016

AREAS AFFECTED...PORTIONS OF NORTHERN OKLAHOMA AND SOUTHERN KANSAS

CONCERNING...SEVERE POTENTIAL...WATCH UNLIKELY 

VALID 082027Z - 082300Z

PROBABILITY OF WATCH ISSUANCE...20 PERCENT

SUMMARY...THE OKLAHOMA-KANSAS BORDER REGION AND VICINITY IS BEING
MONITORED FOR AN INCREASING SVR-TSTM POTENTIAL THIS AFTERNOON...WITH
THE SVR POTENTIAL LINGERING INTO THE EVENING HOURS. PRESENT
INDICATIONS ARE THAT WW ISSUANCE IS UNLIKELY...THOUGH
CONVECTIVE/ENVIRONMENTAL TRENDS WILL CONTINUE TO BE MONITORED.

DISCUSSION...DIFFERENTIAL HEATING IN PROXIMITY TO A
CLOUD-COVERAGE-GRADIENT ZONE EXTENDING W/E ACROSS SRN KS IS
ENHANCING BAROCLINIC CIRCULATIONS. THIS IS FOSTERING THE RECENT
TREND OF INCREASING VERTICAL DEVELOPMENT OF CUMULUS FIELDS ACROSS
SRN KS -- FROM S OF DODGE CITY TO S OF WICHITA. MEANWHILE...
ISENTROPIC ASCENT ATOP MODIFYING CONVECTIVE OUTFLOW FROM SERN KS
THROUGH NERN OK IS ALSO PROVIDING A FOCUSED ZONE OF TOWERING
CUMULUS/ISOLATED CONVECTIVE DEVELOPMENT. CONTINUED SFC HEATING
AMIDST THE WARM/MOIST AIR MASS -- CHARACTERIZED BY DEWPOINTS IN THE
LOWER 70S -- ON THE WARM SIDE OF THE DIFFERENTIAL-HEATING
ZONE/OUTFLOW BOUNDARY -- IS SUPPORTING MLCAPE ON THE ORDER OF
1500-2500 J/KG.

THE LAMONT OK 17Z RAOB SAMPLED RELATIVELY NOTABLE MLCINH...THOUGH
MODIFICATIONS TO THE THERMODYNAMIC PROFILE TO ACCOUNT FOR CURRENT
SFC OBSERVATIONS SUGGEST THAT ANTECEDENT CAPPING HAS ERODED DURING
THE PAST FEW HOURS. AS SUCH...THERE IS INCREASING CONCERN THAT
SFC-BASED CONVECTIVE INITIATION WILL OCCUR ON A MORE WIDESPREAD
BASIS IN THE 2130Z-0000Z TIME-FRAME. INITIAL ACTIVITY SHOULD BE
FOCUSED IN PROXIMITY TO THE AFOREMENTIONED DIFFERENTIAL-HEATING
ZONE/OUTFLOW BOUNDARY. CONVECTION SHOULD GENERALLY SPREAD EWD
THROUGH THE LATE AFTERNOON/EVENING HOURS. HOWEVER...PREFERENTIAL
DEVELOPMENT INTO THE WEAKLY CAPPED ENVIRONMENT FARTHER S INTO OTHER
PARTS OF NRN OK WILL BE LIKELY INTO THE EVENING -- ESPECIALLY AS A
SLY LLJ STRENGTHENS IN ASSOCIATION WITH GRADUAL NOCTURNAL DECOUPLING
OF THE BOUNDARY LAYER.

PRESENT INDICATIONS ARE THAT THE PRIMARY SVR HAZARD WILL BE ISOLATED
SVR WIND GUSTS...ENHANCED BY WATER LOADING RELATED TO PW AROUND 2.17
INCHES PER THE LAMONT RAOB. THIS RAOB INDICATES A MODEST 20-25 KT OF
DEEP SHEAR...WHICH MAY SUPPORT LOCALIZED CONVECTIVE CLUSTERING --
WITH LOCALIZED INSTANCES OF COLD-POOL AMALGAMATION ENCOURAGING THE
RISK FOR STRONG WIND GUSTS. HOWEVER...WITH ONLY MODERATE MID-LEVEL
LAPSE RATES IN PLACE...THE LACK OF STRONGER DEEP SHEAR...AND THE
DEARTH OF LARGE-SCALE ASCENT...A MORE SUBSTANTIAL SVR RISK IS
UNLIKELY. STRONGER DEEP SHEAR SHOULD REMAIN CONFINED TO AREAS
FARTHER N. NEVERTHELESS...A FOCUSED CORRIDOR OF ISOLATED SVR RISK
WILL LIKELY PERSIST THROUGH THE EVENING HOURS...AS THE NOCTURNALLY
STRENGTHENING LLJ FOSTERS REGENERATING CONVECTION IN THE RELATIVELY
HIGH-PW ENVIRONMENT.

..COHEN/HART.. 09/08/2016

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

ATTN...WFO...TSA...ICT...OUN...DDC...AMA...

LAT...LON   35859478 36039670 36379957 36650082 37250069 37519957
            37409694 37049542 36569465 35859478 

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