NWS STORM PREDICTION CENTER NORMAN OK
0235 PM CDT WED APR 10 2013
VALID 102000Z - 111200Z
...THERE IS A SLGT RISK OF SVR TSTMS LATE THIS AFTERNOON AND EVENING
IN A CORRIDOR ACROSS PARTS OF THE LOWER AND MIDDLE MISSISSIPPI
VALLEYS....AS WELL AS A CORRIDOR NORTH OF THE OHIO RIVER INTO THE
NORTHERN MID ATLANTIC COAST...
...20Z OUTLOOK UPDATE...
NO SUBSTANTIVE CHANGES HAVE BEEN MADE TO THE 1630Z OUTLOOK...ASIDE
FROM DECREASING AREAL COVERAGE WITH RISK FOR THUNDERSTORMS ACROSS
THE FLORIDA PENINSULA.
SUBTROPICAL RIDGING CENTERED OFF THE SOUTH ATLANTIC COAST REMAINS
STRONG...WITH BROADLY ANTICYCLONIC LOW-LEVEL FLOW LINGERING AS FAR
WEST AS THE LOWER MISSISSIPPI VALLEY...AND AS FAR NORTH AS THE OHIO
VALLEY/NORTHERN MID ATLANTIC COAST REGION. SEVERAL CLUSTERS OF
THUNDERSTORMS ARE CURRENTLY EVOLVING ALONG THE EDGE OF STRONGER
CAPPING ON NORTHWESTERN AND NORTHERN PERIPHERY OF THIS FEATURE...
WHERE WEAK TO MODERATE INSTABILITY IN THE PRESENCE OF MODERATELY
STRONG AND SHEARED DEEP LAYER WESTERLY FLOW WILL SUPPORT A RISK FOR
DAMAGING WIND GUSTS AND HAIL LATE THIS AFTERNOON AND EVENING.
FORCING ASSOCIATED WITH A SHORT WAVE IMPULSE LIFTING OUT OF THE BASE
OF AMPLIFIED UPPER TROUGHING ACROSS THE PLAINS/SOUTHERN ROCKIES
REGION DOES STILL APPEAR LIKELY TO ENHANCE SEVERE WEATHER POTENTIAL
IN AT LEAST A NARROW CORRIDOR ACROSS CENTRAL/EASTERN ARKANSAS INTO
SOUTHEAST MISSOURI LATE THIS AFTERNOON AND EVENING. BETWEEN THE
SUBTROPICAL RIDGING...AND COLD AIR WHICH HAS DAMMED SOUTHWARD
THROUGH THE PLAINS...AN AXIS OF SURFACE PRESSURE FALLS IS EXPECTED
TO DEVELOP...AND FOCUS STRONGER BOUNDARY LAYER BASED STORM
DEVELOPMENT BY 23-00Z. HIGH BOUNDARY LAYER MOISTURE CONTENT AND
HUMIDITY...MODERATELY LARGE CAPE...STRONG DEEP LAYER SHEAR AND
SIZABLE CLOCKWISE CURVED LOW-LEVEL HODOGRAPHS MAY PROVE FAVORABLE
FOR THE DEVELOPMENT OF DISCRETE SUPERCELLS CAPABLE OF PRODUCING
TORNADOES...IN ADDITION TO LARGE HAIL. THE WINDOW OF OPPORTUNITY
FOR THIS ACTIVITY...BEFORE THE COLD FRONT TO THE WEST BEGINS TO
ADVANCE MORE RAPIDLY EASTWARD...AND THE BOUNDARY LAYER AHEAD OF IT
BEGINS TO STABILIZE...MAY BE SOMEWHAT LIMITED...PRECLUDING AN
UPGRADE OF SEVERE PROBABILITIES AT THE PRESENT TIME.
..KERR.. 04/10/2013
.PREV DISCUSSION... /ISSUED 1122 AM CDT WED APR 10 2013/
...NRN LA AND CENTRAL/ERN AR TO IL THROUGH TONIGHT...
A MIDLEVEL LOW IS EXPECTED TO DEEPEN OVER THE CENTRAL PLAINS TODAY
AND THE MID MO VALLEY TONIGHT...AS AN EMBEDDED JET STREAK ROTATES
NNEWD FROM W TX TO OK/KS. IN RESPONSE...SLOW DEEPENING OF THE
SURFACE LOW IS EXPECTED NEAR STL...WHILE THE TRAILING COLD FRONT
MOVES ONLY SLOWLY EWD ACROSS THE OZARK PLATEAU THROUGH THIS
AFTERNOON...AND MORE QUICKLY SEWD TOWARD THE TX COAST. IN ADVANCE
OF THE FRONT...A PLUME OF RICH LOW-LEVEL MOISTURE ORIGINATING FROM
THE NW CARIBBEAN HAS SPREAD INLAND ACROSS LA/AR...WHERE BOUNDARY
LAYER DEWPOINTS HAVE REACHED THE UPPER 60S TO NEAR 70 F. THIS
MOISTENING HAS OCCURRED BENEATH A REMNANT EML PLUME WITH MIDLEVEL
LAPSE RATES OF 7.5-8.5 C/KM.
VISIBLE IMAGERY SHOWS SOME CLOUD BREAKS ACROSS MUCH OF AR...WHICH
WILL ALLOW SURFACE TEMPERATURES TO WARM WELL INTO THE 70S THIS
AFTERNOON...AND SUPPORT MLCAPE NEAR 2500 J/KG. ALSO...THE SLY LLJ
WILL INCREASE GRADUALLY THIS AFTERNOON THROUGH EARLY TONIGHT FROM
CENTRAL/ERN AR TO IL/INDIANA...IN RESPONSE TO THE DEEPENING MID MS
VALLEY LOW. LIKEWISE...MID-UPPER SWLY FLOW WILL INCREASE WITH THE
GLANCING INFLUENCE OF THE JET STREAK EJECTING NNEWD OVER ERN OK/KS.
THE NET RESULT WILL BE AN ENVIRONMENT WITH MODERATE INSTABILITY AND
INCREASINGLY FAVORABLE LOW-LEVEL AND DEEP-LAYER VERTICAL SHEAR FOR
SUPERCELLS /EFFECTIVE SRH APPROACHING 300 M2 PER S2 AND EFFECTIVE
BULK SHEAR NEAR 50 KT/.
GIVEN THE RELATIVELY SLOW MOTION OF THE COLD FRONT ACROSS WRN AR
THIS AFTERNOON...AND SUBSTANTIALLY RICHER LOW-LEVEL MOISTURE ACROSS
LA/AR COMPARED TO AREAS FARTHER W IN PREVIOUS DAYS...THE RISK FOR
SUPERCELLS BOTH ALONG AND A LITTLE AHEAD OF THE COLD FRONT WILL BE
GREATER COMPARED TO PREVIOUS DAYS. THIS WILL SUPPORT AN INCREASING
RISK FOR A FEW TORNADOES LATER THIS AFTERNOON INTO THIS EVENING
ACROSS CENTRAL/ERN AR INTO SE MO...AND POTENTIALLY AN ISOLATED
STRONG TORNADO IF A SEMI-DISCRETE STORM CAN BE MAINTAINED FOR A
COUPLE OF HOURS. LARGE HAIL AND DAMAGING WINDS CAN ALSO BE EXPECTED
WITH WHAT SHOULD EVOLVE INTO A SOMEWHAT SOLID FRONTAL SQUALL LINE BY
EARLY TONIGHT. THE ERN EXTENT OF THE SEVERE RISK OVERNIGHT WILL BE
LIMITED BY SLOW EWD MOTION OF THE FRONT...AND BY WEAKENING
INSTABILITY ACROSS ERN MS/AL INTO MIDDLE TN WHERE LOW-LEVEL IS MORE
LIMITED BY TRAJECTORIES FROM WITHIN THE LINGERING RIDGE OVER THE SE
STATES.
...OH VALLEY TO MID ATLANTIC THROUGH THIS EVENING...
A FEW SMALL CLUSTERS OF THUNDERSTORMS HAVE ALREADY DEVELOPED ACROSS
OH AS OF LATE MORNING...AND THIS CONVECTION SHOULD PERSIST THROUGH
THE AFTERNOON WHILE SPREADING EWD INTO PA. INSTABILITY IS NOT
PARTICULARLY STRONG...WITH THE GREATEST LOW-LEVEL MOISTURE FEED INTO
THE OH VALLEY FROM THE SW...BUT STRONG SURFACE HEATING AND STEEP
LOW-LEVEL LAPSE RATES EXTEND EWD TO THE MID ATLANTIC COAST. GIVEN
THE LARGELY UNIDIRECTIONAL WLY WIND PROFILES WITH UP TO 50 KT FLOW
AROUND 500 MB...ISOLATED DAMAGING GUSTS WILL BE POSSIBLE...AS WELL
AS MARGINALLY SEVERE HAIL W OF THE APPALACHIANS.
CLICK TO GET WUUS01 PTSDY1 PRODUCT
I couldn't believe it, right now!? That was the 2nd time I was on the toilet this year when I heard CNN break into live coverage with a tornado threatening areas 
. It looks like a nice hook and I'm watching Brett Adair on live stream of what is a large tornado!:
