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000
ACUS11 KWNS 230945
SWOMCD
SPC MCD 230945
OKZ000-231145-

MESOSCALE DISCUSSION 0776
NWS STORM PREDICTION CENTER NORMAN OK
0445 AM CDT THU MAY 23 2013

AREAS AFFECTED...PARTS OF CENTRAL AND SRN OK

CONCERNING...SEVERE POTENTIAL...WATCH UNLIKELY

VALID 230945Z - 231145Z

PROBABILITY OF WATCH ISSUANCE...20 PERCENT

SUMMARY...ELEVATED TSTMS WILL CONTINUE TO DEVELOP DURING THE EARLY
MORNING HOURS ACROSS CENTRAL OK AND GIVEN WNWLY FLOW ALOFT...THIS
ACTIVITY WILL TRACK ESEWD INTO SOUTH CENTRAL-SERN OK. HAIL WILL BE
THE PRIMARY THREAT...WITH THE POTENTIAL FOR SOME HAILSTONES REACHING
1 INCH DIAMETER.  AT THIS TIME...OVERALL SEVERE WEATHER COVERAGE IS
NOT ANTICIPATED TO SUPPORT A WATCH ISSUANCE...BUT TRENDS WILL BE
MONITORED.

DISCUSSION...EARLY MORNING RADAR MOSAIC SHOWED TSTMS DEVELOPING IN A
NARROW NW-SE ORIENTED CORRIDOR FROM BLAINE COUNTY THROUGH THE OKC
METRO INTO MCCLAIN AND CLEVELAND COUNTIES.  THIS ACTIVITY IS LOCATED
WITHIN THE NOSE OF A 45-55 KT SSWLY LLJ EXTENDING FROM CENTRAL TX
INTO CENTRAL OK WHERE WAA IS BEING ENHANCED NORTH OF AN E-W ORIENTED
SURFACE BOUNDARY LOCATED ACROSS FAR N TX.  DESPITE THE LACK OF ANY
APPARENT MIDLEVEL IMPULSE PER WATER VAPOR IMAGERY...AREA VWPS
INDICATED A RECENT STRENGTHENING OF NWLY MIDLEVEL WINDS OVER CENTRAL
OK /UP TO 40 KT/.  THIS COMBINED WITH THE LLJ IS RESULTING IN
EFFECTIVE BULK SHEAR OF 40-50 KT...SUFFICIENT FOR STORM
ORGANIZATION.  THE INFLUX OF MARGINAL-MODERATE INSTABILITY INTO
CENTRAL OK AND THE STRONGER BULK SHEAR SUGGESTS SOME OF THE STRONGER
CORES COULD INTENSIFY TO SEVERE LEVELS PRODUCING A HAIL THREAT.
MIDLEVEL LAPSE RATES HAVE INCREASED OVER CENTRAL OK SINCE 00Z...PER
THE 06Z LAMONT SOUNDING INDICATING 700-500 MB LAPSE RATES OF 8.5
C/KM.  THIS FACTOR WILL FURTHER ENHANCE THE HAIL THREAT...BUT THE
LACK OF DISCERNIBLE MID-UPPER LEVEL FORCING...GIVEN HEIGHT
RISES...SHOULD LIMIT THE COVERAGE OF STRONGER STORMS.

ALTHOUGH HIGH-RES CONVECTIVE ALLOWING MODELS /00Z NAM 4KM...00Z NSSL
4 KM...AND THE 01Z HRRR/ ARE 2-3 HOURS TOO SLOW AT DEVELOPING THE
CENTRAL OK STORMS...EACH OF THESE MODELS WERE SIMILAR IN THE
EVOLUTION AND TRACK OF THESE EARLY MORNING STORMS.  AND...SUGGESTED
THE OVERALL TSTM ACTIVITY WILL PERSIST FOR 5-6 HOURS THIS
MORNING...PRIOR TO THE EXPECTED WEAKENING OF THE LLJ.

..PETERS/HART.. 05/23/2013

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

ATTN...WFO...OUN...

LAT...LON   36329876 35979787 35619727 34899658 34479650 34079636
            33939670 34129762 34509828 35129880 35809891 36329876

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