Location:

ACUS01 KWNS 122003

SWODY1

SPC AC 122002



DAY 1 CONVECTIVE OUTLOOK  

NWS STORM PREDICTION CENTER NORMAN OK

0202 PM CST FRI MAR 12 2010



VALID 122000Z - 131200Z



...THERE IS A SLGT RISK OF SVR TSTMS FROM THE OH VALLEY SWD TO ERN

AL/GA AND ERN FL PANHANDLE...



...THERE IS A SLGT RISK OF SVR TSTMS ACROSS FAR S FL...



...OH RIVER VALLEY SWD TO ERN AL/GA...

SHORTWAVE TROUGH WILL CONTINUE TO MOVE NWD THROUGH THE LOWER OH/MID

MS VALLEYS...WHILE THE SRN EXTENSION OF THIS VORTICITY SPREADS EWD

INTO THE SERN STATES.  FORECAST REMAINS ON TRACK FOR A CONTINUED

SEVERE POTENTIAL FROM THE LOWER OH RIVER VALLEY SWD ALONG AND JUST

AHEAD OF AN E/NEWD MOVING COLD FRONT.  A NARROW CORRIDOR OF HIGHER

BOUNDARY LAYER MOISTURE ALONG AND JUST E OF THE FRONT AND BENEATH

STEEP MID LEVEL LAPSE RATES ARE SUPPORTING SOME INSTABILITY...

THOUGH IT SHOULD REMAIN MARGINAL GIVEN EXTENSIVE CLOUD COVER. 

HOWEVER...STRONGER SURFACE HEATING ACROSS ERN KY/SRN OH FROM DOWN

SLOPE WIND FLOW IS SUPPORTING A SLIGHTLY GREATER AREA OF

INSTABILITY.



MODERATE-STRONG DEEP SSELY TROPOSPHERIC WINDS SUPPORTING EFFECTIVE

BULK SHEAR 35-50 KT WITHIN THE SLIGHT RISK AREA SUGGESTS STRONG TO

SEVERE STORMS WILL REMAIN POSSIBLE WITH HAIL...STRONG WIND GUSTS AND

AN ISOLATED TORNADO UNTIL SUNSET.





...FAR S FL...

MID AFTERNOON REGIONAL RADARS INDICATED A BAND OF STRONG TO SEVERE

STORMS MOVING SSEWD ACROSS FAR S FL.  AIR MASS AHEAD OF THIS

ACTIVITY REMAINS MODERATELY UNSTABLE AND STRONGLY SHEARED...

SUPPORTING THE THREAT FOR SEVERE STORMS UNTIL THIS ACTIVITY MOVES

OFFSHORE BY LATE AFTERNOON.  SHOWERS/TSTMS WILL REMAIN POSSIBLE IN

THE WAKE OF THIS ACTIVITY...NWD ACROSS THE PENINSULA...AS FORCING

FOR ASCENT ATTENDANT TO SRN LOBE OF VORTICITY WITH TN/OH VALLEYS

SYSTEM SPREADS EWD.  WEAK INSTABILITY WILL PRECLUDE A SEVERE WEATHER

THREAT WITH THAT ACTIVITY.



..PETERS.. 03/12/2010



.PREV DISCUSSION... /ISSUED 1030 AM CST FRI MAR 12 2010/



...SYNOPSIS...

COMPLEX SITUATION THIS MORNING WITH SEVERAL POTENTIAL SEVERE THREAT

AREAS...EACH OF WHICH HAS SOME LIMITING FACTORS.  ON THE LARGER

SCALE...A DEEP CLOSED LOW CENTERED NEAR THE KS/NE/MO BORDER REGION

WILL CONTINUE TO MOVE SEWD TOWARD THE MID SOUTH BY LATE

TONIGHT...WHILE ONE EMBEDDED SHORTWAVE TROUGH ROTATES NNEWD FROM NRN

MS/AL TO THE LOWER OH VALLEY...AND ANOTHER WAVE PROGRESSES EWD FROM

THE LOWER MS VALLEY TO N FL AND THE SE ATLANTIC COAST.  AT THE

SURFACE...A WEAK CYCLONE INVOF ERN TN/KY WILL DEVELOP NWD THROUGH

THE AFTERNOON...WHILE ADDITIONAL CYCLOGENESIS IS EXPECTED OVERNIGHT

IN THE LEE OF THE APPALACHIANS.  THIS NC/VA CYCLOGENESIS PROCESS AND

THE RESULTANT DISTRIBUTION OF THE WARM SECTOR WILL BE COMPLICATED BY

A PRE-EXISTING CYCLONE OFF THE NC COAST.  FARTHER S...A TRAILING

COLD FRONT IS EXPECTED TO MOVE EWD ACROSS THE FL PANHANDLE AND SW GA

THIS AFTERNOON...AND CONTINUE ACROSS ALL OF FL AND THE SE ATLANTIC

COAST OVERNIGHT.



...S FL THIS AFTERNOON/EVENING...

A LARGE CLUSTER OF THUNDERSTORMS AND AN ASSOCIATED OUTFLOW BOUNDARY

CONTINUE TO SAG SWD INTO S FL...WITH WIDESPREAD RAINFALL REINFORCING

THE COLD POOL.  MODERATE INSTABILITY IS PRESENT S OF THE

BOUNDARY...WITH SUFFICIENT DEEP-LAYER VERTICAL SHEAR FOR EMBEDDED

BOWING SEGMENTS AND SUPERCELLS.  THE PRIMARY CONCERN ACROSS THIS

AREA WILL BE THE TENDENCY FOR THE STRONGER CONVECTION TO BE UNDERCUT

BY THE SWD MOVING OUTFLOW.  HOWEVER...BOUNDARY MOTION HAS BEEN

SLOW...AND THE THREAT FOR DAMAGING WINDS/HAIL AND AN ISOLATED

TORNADO OR TWO SHOULD INCREASE THIS AFTERNOON AS A STRONGER CLUSTER

OF STORMS JUST OFF THE W/SW FL COAST MOVES INLAND ALONG THE

BOUNDARY.



...OH RIVER VALLEY SWD TO ERN AL/GA TODAY...

A WEAK SURFACE LOW WILL PRECEDE THE EJECTING MID LEVEL TROUGH NOW

OVER NRN MS/WRN TN.  ISOLATED STRONG/SEVERE STORMS ARE ONGOING AS OF

MID MORNING FROM NE AL NWD INTO CENTRAL KY...WITH THE STRONGER

STORMS IN AL ALONG THE N EDGE OF THE SOMEWHAT STRONGER INSTABILITY. 

THE NE AL/TN/KY CONVECTION SHOULD PERSIST THROUGH THE AFTERNOON IN

CONJUNCTION WITH THE NWD MOVEMENT OF THE STRONGER LOW-MIDLEVEL

ASCENT AND LOW-LEVEL FLOW RESPONSE PRECEDING THE EJECTING MIDLEVEL

WAVE.  THE DEGREE OF INSTABILITY INTO TN/KY IS IN QUESTION GIVEN THE

WIDESPREAD CLOUD COVER.  STILL...SOME SURFACE HEATING IN CLOUD

BREAKS AND THE PRESENCE OF BOUNDARY LAYER DEWPOINTS IN THE 50S COULD

RESULT IN SUFFICIENT INSTABILITY FOR LINE SEGMENTS CAPABLE OF

PRODUCING DAMAGING WINDS...ALONG WITH SMALL SUPERCELLS AND THE

POTENTIAL FOR MARGINALLY SEVERE HAIL AND AN ISOLATED TORNADO.  



FARTHER S...A FEW THUNDERSTORMS ARE DEVELOPING ALONG AND IN ADVANCE

OF THE SURFACE COLD FRONT WHICH IS MOVING EWD FROM ERN AL TO WRN GA

AND THE FL PANHANDLE.  A FEW CLOUD BREAKS ARE BEGINNING TO FORM OVER

SW GA...THOUGH PRE-FRONTAL AFTERNOON SURFACE CONDITIONS WILL LIKELY

CONSIST OF TEMPERATURES IN THE 60S WITH DEWPOINTS OF 56-62 F.  THE

NET RESULT WILL BE WEAK-MODERATE INSTABILITY WITH LARGELY

UNIDIRECTIONAL WIND PROFILES.  ISOLATED SUPERCELLS WILL BE POSSIBLE

IN THE BROKEN FRONTAL BAND ACROSS ERN AL INTO GA THIS

AFTERNOON...WITH LARGE HAIL AND DAMAGING GUSTS THE MAIN SEVERE

THREATS.