Monday, September 27, 2010

DAY1SVR: Day 1 Convective Outlook Amend 1

ACUS01 KWNS 272252
SWODY1
SPC AC 272251

DAY 1 CONVECTIVE OUTLOOK AMEND 1
NWS STORM PREDICTION CENTER NORMAN OK
0551 PM CDT MON SEP 27 2010

VALID 272245Z - 281200Z

...THERE IS A SLGT RISK OF SVR TSTMS FROM SERN PA/SRN NJ AND THE
DELMARVA REGION SWD ACROSS THE CAROLINAS AND WWD TO NRN/CENTRAL
GA...

AMENDED TO EXPAND THE SLIGHT RISK WWD ACROSS WRN SC/NC INTO NRN AND
CENTRAL GA

...CENTRAL-NRN GA INTO PARTS OF WRN SC/NC...
THE DESTABILIZED ENVIRONMENT ACROSS THIS REGION WILL CONTINUE TO
SUPPORT AN INCREASED SEVERE WEATHER THREAT /MAINLY HAIL AND STRONGER
WIND GUSTS/ THROUGH 01-03Z. THE 18Z AND 19Z WRF-HRRR SUGGESTS THE
ONGOING STORMS OVER THE NRN HALF OF GA MAY BECOME MORE LINEAR THIS
EVENING AS THE ACTIVITY SPREADS ENEWD INTO WRN SC AND ADJACENT SWRN
NC.

IN ADDITION TO INTRODUCING SEVERE HAIL PROBABILITIES TO THIS UPDATED
OUTLOOK...THE 15 PERCENT SEVERE WIND PROBABILITY LINE WAS EXPANDED
WSWWD AS WELL AS THE 5 PERCENT PROBABILITY FOR TORNADOES BEING
EXPANDED WSWWD INTO NERN GA.

FOR ADDITIONAL SHORT TERM MESOSCALE DETAILS...REFER TO SPC MESOSCALE
DISCUSSION #1900.
/PETERS


.PREV DISCUSSION... /ISSUED 0255 PM CDT MON SEP 27 2010/
...ATLANTIC COAST STATES...
VERY LITTLE CHANGE HAS BEEN MADE TO THE ONGOING FORECAST...AS
LIMITED SEVERE THREAT PERSISTS -- ACROSS BOTH THE NRN GA/WRN
CAROLINAS REGION WITHIN THE DESTABILIZING DRY SLOT AHEAD OF THE
UPPER LOW...AND ACROSS THE DELMARVA REGION AND VICINITY WHERE MORE
FAVORABLE LOW-LEVEL SHEAR IS JUXTAPOSED WITH MODEST INSTABILITY.

ONE CHANGE OF NOTE WAS IMPLEMENTED ACROSS SERN GA...WHERE SLIGHT
RISK HAS BEEN REMOVED AS THE BAND OF STRONGEST CONVECTION CONTINUES
SHIFTING INTO THE WRN ATLANTIC...LEAVING A MORE STABLE AIRMASS IN
ITS WAKE.
/GOSS

..PETERS/GOSS.. 09/27/2010

.PREV DISCUSSION... /ISSUED 1124 AM CDT MON SEP 27 2010/

A LARGE UPPER LOW OVER THE GULF COAST STATES WILL ROTATE EASTWARD
ACROSS THE SOUTHEAST US LATER TODAY AND TONIGHT. THIS WILL CONTINUE
TO RESULT IN WIDESPREAD SHOWERS AND THUNDERSTORMS OVER A LARGE AREA
OF THE SOUTHEAST...INCLUDING A RISK OF LOCALLY SEVERE STORMS.

...SC/NC COAST SHORT-TERM...
MORNING RADAR/SATELLITE IMAGERY SHOW A COMPLEX SETUP ACROSS GA/SC/NC
WITH SEVERAL CLUSTERS OF THUNDERSTORMS. THE EFFECTIVE OUTFLOW
BOUNDARY HAS MOVED TO NEAR THE COAST...SUGGESTING THAT THE GREATEST
SHORT-TERM RISK OF SEVERE IS LIKELY CONFINED TO THE IMMEDIATE
COASTAL AREAS OF SC...AND FAR EASTERN NC. SMALL BOWING SEGMENTS
ALONG THE LEADING EDGE OF THIS CONVECTION MAY POSE A RISK OF LOCALLY
DAMAGING WINDS OR AN ISOLATED TORNADO.

...CENTRAL NC INTO DELMARVA...
LATER THIS AFTERNOON...SOME MODEL SOLUTIONS AND SATELLITE TRENDS
INDICATE A POTENTIAL FOR DESTABILIZATION OVER CENTRAL NC NEAR THE
REMNANT FRONT. STRONG VERTICAL SHEAR WILL BE IN PLACE OVER THIS
REGION AS THE UPPER WAVE APPROACHES FROM THE SOUTHWEST. A POCKET OF
COOLER TEMPERATURES ALOFT AND STEEPENING LAPSE RATES MAY PROVIDE
SUFFICIENT THERMODYNAMIC SUPPORT FOR THE DEVELOPMENT OF ISOLATED
STORMS CAPABLE OF DAMAGING WINDS OR A TORNADO. THESE STORMS WILL
TRACK NORTHEASTWARD AFTER DARK INTO PARTS OF VA AND EVENTUALLY
NJ/DE/MD WITH A CONTINUED SEVERE RISK.

...NORTHERN GA...
FINALLY...THE POCKET OF STEEPER LAPSE RATES CURRENTLY OVER
AL/GA...COUPLED WITH DECREASING CLOUDS OVER GA...MAY RESULT IN
SCATTERED LOW-TOPPED THUNDERSTORMS THIS AFTERNOON. THIS AREA MAY
SEE A FEW STRONG STORMS WITH DAMAGING WINDS POSSIBLE.

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