SWODY1
SPC AC 191940
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0240 PM CDT TUE JUN 19 2007
VALID 192000Z - 201200Z
..THERE IS A SLGT RISK OF SVR TSTMS ACROSS THE NERN U.S...INCLUDING
PORTIONS OF THE UPPER OH VALLEY...
..THERE IS A SLGT RISK OF SVR TSTMS ACROSS PORTIONS OF THE CENTRAL
GULF STATES...
..THERE IS A SLGT RISK OF SVR TSTMS ACROSS MUCH OF THE CENTRAL /
SOUTHERN PLAINS...
..UPPER OH VALLEY...NY...VT...
VERY STEEP BOUNDARY LAYER LAPSE RATES HAVE EVOLVED EAST OF THE
APPALACHIANS FROM THE MIDDLE ATLANTIC...NWD INTO SRN QUEBEC WHERE
SFC-3KM VALUES ARE NOW ON THE ORDER OF 8-9 C/KM. SFC TEMPERATURES
HAVE WARMED WELL INTO THE 80S TO NEAR 90F...ESSENTIALLY REMOVING ANY
MEAGER INHIBITION NOTED ON EARLY MORNING SOUNDINGS. AS A RESULT...A
PRE-FRONTAL BAND OF INTENSIFYING THUNDERSTORMS IS NOW ORGANIZING
FROM UPSTATE NY...SWWD INTO THE WV PANHANDLE. THIS ACTIVITY WILL
CONTINUE TO ORGANIZE AS IT SPREADS EWD.
UPSTREAM...NUMEROUS THUNDERSTORMS ARE ONGOING ALONG/AHEAD OF COLD
FRONT WHICH IS NOW SPREADING ACROSS OH INTO SRN ONTARIO. DAMAGING
WINDS AND PERHAPS SOME HAIL WILL LIKELY ACCOMPANY MOST STORMS ACROSS
THE SLIGHT RISK REGION INTO THE EVENING HOURS. SIGNIFICANT
OVERTURNING DUE TO WIDESPREAD CONVECTION WILL LIKELY RESULT IN
LESSENING SEVERE THREAT BY MID EVENING.
..GULF STATES...
SECONDARY MCS IS EXPANDING IN AREAL COVERAGE OVER CNTRL MS...IN THE
WAKE OF MORE EXPANSIVE THUNDERSTORM COMPLEX NOW SPREADING DOWNSTREAM
ACROSS ERN AL INTO GA. A WELL DEFINED MCV HAS EVOLVED OVER WINSTON
COUNTY MS AND A STRONG SWD SURGE IS NOW EVIDENT AS DEEP LAYER FLOW
VEERS TO A NLY COMPONENT. ALTHOUGH NUMEROUS SEE BREEZE
SHOWERS/THUNDERSTORMS HAVE EVOLVED AHEAD OF THIS ACTIVITY FROM CNTRL
LA INTO SRN AL...IT APPEARS THE CONVECTIVE COMPLEX OVER CNTRL MS
WILL MAINTAIN ITS STRONG SWD SURGE...POSSIBLY SPREADING TO THE MS
COAST LATER THIS EVENING.
..CENTRAL / SOUTHERN PLAINS...
MID DAY SOUNDINGS FROM BOTH OUN AND AMA INDICATE EXTREME INSTABILITY
HAS DEVELOPED ACROSS THE SRN PLAINS INTO PORTIONS OF THE CNTRL
PLAINS. MLCAPE VALUES ARE NOW ON THE ORDER OF 4000-6500 J/KG FROM
THE RED RIVER INTO WRN KS...COINCIDENT AND JUST SOUTH OF A WELL
DEFINED LOW LEVEL CONFLUENT ZONE THAT STRETCHES FROM CNTRL
AR...ARCING NWWD INTO DEVELOPING THUNDERSTORMS NEAR THE NEB BORDER.
THIS DEVELOPING CONVECTION APPEARS TO BE PARTLY INFLUENCED BY WEAK
DISTURBANCE MOVING ESEWD ACROSS NEB...AIDED BY WEAK WARM ADVECTION
ALONG TRAILING BOUNDARY. IT/S NOT ENTIRELY CLEAR HOW ACTIVE THIS
LOW LEVEL CONFLUENCE ZONE WILL BE TODAY...ESPECIALLY THAT ZONE EAST
OF THE HIGH TERRAIN. WHAT DOES SEEM LIKELY IS THAT CONTINUED STRONG
HEATING ACROSS SERN CO/ERN NM INTO THE TX PANHANDLE WILL AFFECTIVELY
REMOVE WHAT LITTLE INHIBITION REMAINS AND UPSLOPE FLOW SHOULD PROVE
ADEQUATE FOR SUSTAINING UPDRAFTS. LATEST THINKING IS A SMALL
CLUSTER OF THUNDERSTORMS SHOULD ORGANIZE OVER NWRN KS BEFORE
PROPAGATING SWD ALONG INSTABILITY AXIS BENEATH WEAKENING FLOW ALOFT.
ADDITIONAL STORMS SHOULD EVOLVE SOUTH OF THIS ZONE INTO THE TX
PANHANDLE LATER THIS AFTERNOON. VERY LARGE HAIL IS THE MOST LIKELY
SEVERE THREAT...ALONG WITH STRONG WINDS.
.DARROW.. 06/19/2007
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