SPC AC 231618
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1118 AM CDT FRI JUL 23 2010
VALID 231630Z - 241200Z
...THERE IS A SLGT RISK OF SVR TSTMS FROM THE NRN/CNTRL PLNS INTO
THE UPR MS VLY EWD ACROSS THE LOWER GREAT LAKES TO THE NRN
APPALACHIANS...
...THERE IS A SLGT RISK OF SVR TSTMS PARTS OF SRN FL...
...CENTRAL/NRN PLAINS INTO THE UPPER MS VLY TODAY/TONIGHT...
S/WV TROUGH MT CONTINUES EWD ACROSS THE NRN PLAINS TO UPPER MS
VALLEY BY LATER TONIGHT. SFC COLD FRONT CURRENTLY ERN MT SWWD INTO
NRN WY WILL PUSH SEWD ACROSS WRN DAKOTAS IN ADVANCE OF TROUGH WHILE
A DEVELOPING SURFACE LOW WRN SD DROPS SEWD INTO NRN NEB BY THIS
EVENING. WARM FRONT WILL LIFT NWD AHEAD OF SURFACE LOW INTO SRN SD
BY THIS AFTERNOON AS A MOIST LOW LEVEL AIR MASS SPREADS NWWD THRU
ERN NEB INTO SD.
PLUME OF STEEP MID LEVEL LAPSE RATES ADVECTING EWD AHEAD OF COLD
FRONT/UPPER TROUGH ACROSS SD/NE IN CONCERT WITH DEWPOINTS TO NEAR
70F WILL LEAD TO A MDTLY UNSTABLE AIR MASS WITH MLCAPES AOA 3000
J/KG BY MID AFTERNOON VICINITY WARM FRONT/AHEAD OF SURFACE LOW.
LARGE SCALE ASCENT SPREADING EWD WITH TROUGH ALONG WITH 35-40KT OF
DEEP LAYER SHEAR WILL LEAD TO DEVELOPMENT OF SEVERE THUNDERSTORMS BY
LATER THIS AFTERNOON FROM WRN/CENTRAL SD SWD INTO NRN NEB.
PARAMETERS SUPPORT SUPERCELL POTENTIAL INCLUDING VERY LARGE HAIL AND
ISOLATED TORNADOES.
BY THIS EVENING STORMS EXPECTED TO DEVELOP UPSCALE INTO A FORWARD
PROPAGATING MCS VICINITY WARM FRONT THAT WILL EXTEND EWD VICINITY
MN/IA BORDER. WIND DAMAGE WILL THEN BECOME PRIMARY SEVERE THREAT AT
THIS STAGE.
...MID WEST/OH VLY INTO LWR GRT LAKES/NRN APPALACHIANS...
PLUME OF VERY HIGH PWAT IN EXCESS OF 2 INCHES EXTENDS EWD VICINITY
STALLED FRONTAL ZONE FROM IA EWD SRN LM AND INTO WRN NY. SURFACE
HEATING HAS RAPIDLY DIMINISHED THE CINH TO S OF FRONTAL ZONE WITH
SBCAPES IN EXCESS OF 3000 J/KG WHERE SURFACE TEMPS HAVE WARMED INTO
UPR 80S. THE VERY WARM MID LEVELS AND WEAK LAPSE RATES WILL
SOMEWHAT LIMIT THE SEVERE POTENTIAL. HOWEVER THE 30-40 KT 2-3KM WLY
FLOW COUPLED WITH THE VERY HIGH PWAT WILL LEAD TO A STEADY INCREASE
IN WIND DAMAGE POTENTIAL THROUGH THE AFTERNOON AS SURFACE BASED
STORMS DEVELOP AND BECOME MORE WIDESPREAD. LOW LEVEL CONVERGENCE IS
GENERALLY WEAK WITH THE BEST FOCUS VICINITY LAKE BREEZES ON LE AND
WRN LO.
ADDITIONAL STRONG/SEVERE STORMS WILL LIKELY REDEVELOP VICINITY MS
RIVER IA/IL BY LATER THIS AFTERNOON IN ADVANCE OF THE EXPECTED MCS
THAT WILL BE EVOLVING OVER SD/NE. THE VERY MOIST AND UNSTABLE AIR
MASS IN PLACE WILL FUEL SURFACE BASED STORMS IN THE FAVORABLE LOW
LEVEL CONVERGENCE VICINITY OF E/W OUTFLOW BOUNDARY THAT EXTENDS WWD
FROM NEAR CHI TO W OF MLI. AGAIN WITH WEAK LAPSE RATES DAMAGING
WINDS ALONG WITH HEAVY RAIN WOULD BE PRIMARY THREAT THIS AREA.
FARTHER E...STORMS EXPECTED TO INTENSITY/DEVELOP VICINITY WARM FRONT
OVER PA/NY LATER THIS AFTERNOON. LOW LEVEL SHEAR WILL BE MORE
FAVORABLE THIS REGION AS WARM FRONT CONTINUES TO SHIFT NWD FOR
POSSIBLE ROTATING STORMS AND A TORNADO OR TWO THROUGH THIS EVENING.
THE AMOUNT OF DESTABILIZATION THAT CAN OCCUR IS STILL A QUESTION AS
CURRENT CLOUD COVER WILL SLOW THE HEATING AND POSSIBLY DELAY THE
PRIMARY THREAT UNTIL THIS EVENING.
... S FL...
CIRCULATION CENTER WITH T.S. BONNIE HAS MOVED ONSHORE JUST N OF HST
AT 16Z. BANDS OF CONVECTION WILL CONTINUE TO MOVE ONSHORE NWD TO MLB
FOR NEXT FEW HOURS. WITH 30-40 KT OF LOW LEVEL SHEAR WILL CONTINUE
A THREAT OF ISOLATED TORNADOES.
..HALES/ROGERS.. 07/23/2010
CLICK TO GET WUUS01 PTSDY1 PRODUCT
NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 2000Z
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