[SWODY2] SWODY2

[Severe Weather Outlook - Day 2]

ACUS02 KWNS 210621
SWODY2
SPC AC 210620

DAY 2 CONVECTIVE OUTLOOK  
NWS STORM PREDICTION CENTER NORMAN OK
0120 AM CDT FRI APR 21 2006

VALID 221200Z - 231200Z

...THERE IS A SLGT RISK OF SVR TSTMS ACROSS PARTS OF THE MIDDLE AND
SRN ATLANTIC STATES...

...MID-SRN ATLANTIC STATES...
SRN HIGH PLAINS SHORT WAVE TROUGH MOVING EWD DAY 1 PERIOD SHOULD BE
LOCATED ACROSS THE CENTRAL GULF COAST STATES AT 12Z SATURDAY.  THIS
TROUGH IS THEN EXPECTED TO BECOME SLIGHTLY NEGATIVELY TILTED AS IT
TRACKS NEWD IN LEE OF THE SRN/CENTRAL APPALACHIANS... REACHING THE
DELMARVA REGION BY 12Z SUNDAY. SURFACE LOW ASSOCIATED WITH THIS SRN
STREAM TROUGH SHOULD BE LOCATED OVER THE UPPER TN VALLEY AT THE
START OF THE PERIOD...AND THEN TRACK NEWD ACROSS WRN NC/WRN VA
SATURDAY AFTERNOON...REACHING ERN VA TO DEL LATE IN THE PERIOD. 
COLD FRONT TRAILING SWD ACROSS WRN GA TO THE FL PANHANDLE AND THEN
OFFSHORE WILL MOVE ENEWD ACROSS THE SERN AND MID-ATLANTIC STATES...
AND SHOULD EXTEND FROM SERN VA/ERN NC SWWD TO THE CENTRAL FL
PENINSULA BY THE BEGINNING OF DAY 3.

THUNDERSTORMS...SOME POTENTIALLY SEVERE...ARE EXPECTED TO BE ONGOING
EARLY SATURDAY SWD FROM THE SURFACE LOW ALONG THE COLD FRONT. 
EXTENSIVE CLOUDINESS DOWNSTREAM ACROSS THE WARM SECTOR MAY LIMIT
SURFACE HEATING.  HOWEVER...LOW-LEVEL MOISTURE ADVECTION ACROSS ERN
GA/CAROLINAS INTO SRN VA WITH SURFACE DEWPOINTS IN THE MID 60S
BENEATH MODEST LAPSE RATES SHOULD CONTRIBUTE TO MUCAPES AROUND AT
LEAST 1000 J/KG...WITH POCKETS OF HIGHER INSTABILITY POSSIBLE. 

ONGOING ACTIVITY SHOULD INCREASE IN INTENSITY/COVERAGE AS THE COLD
FRONT SPREADS ENE INTO THE GREATER INSTABILITY ACROSS THE PIEDMONT
AND COASTAL PLAINS OF SC/NC/VA BY SATURDAY AFTERNOON.  SSWLY
UNI-DIRECTIONAL WIND PROFILES WITH SHEAR VECTORS ORIENTED NEARLY
PARALLEL TO THE SURFACE FRONT SUGGEST A LINEAR MODE WITH BOWING
SEGMENTS.  BACKED LOW-LEVEL FLOW ALONG THE TRACK OF THE SURFACE LOW
SHOULD RESULT IN STRONGER DEEP LAYER SHEAR VALUES FOR SUPERCELLS. 
THUS...A FEW TORNADOES...DAMAGING WINDS...AND HAIL WILL BE POSSIBLE.

FARTHER S ACROSS SERN GA/FL PENINSULA...DESPITE LOW-LEVEL FLOW
VEERING IN ADVANCE OF THE FRONT IN GA/NRN FL...STRONG INSTABILITY
AND MODERATE DEEP LAYER SHEAR SHOULD SUPPORT MULTICELLS WITH A
THREAT FOR HAIL/DAMAGING WINDS.  SEA BREEZE BOUNDARY IS EXPECTED TO
BE THE FOCUS FOR THUNDERSTORMS SATURDAY AFTERNOON ACROSS THE
NRN/CENTRAL FL PENINSULA WITH SIMILAR CAPE/SHEAR VALUES SUPPORTING A
THREAT FOR HAIL/DAMAGING WINDS.

...SRN HIGH PLAINS...
MODELS DIFFER WITH THE AMOUNT OF MOISTURE RETURN INTO SWRN-WRN TX/
SERN NM SATURDAY AFTERNOON.  GFS INDICATED THE STRONGEST SIGNAL
SUPPORTING AN AXIS OF MODERATE INSTABILITY ACROSS THIS REGION. 
DESPITE THE UNCERTAINTY IN MOISTURE RETURN...THIS OUTLOOK WILL
MAINTAIN LOW SEVERE PROBABILITIES SINCE INCREASING SWLY MID-LEVEL
FLOW ATOP A STRENGTHENING SSELY LLJ BY EARLY EVENING WOULD RESULT
SUFFICIENT DEEP LAYER SHEAR FOR ORGANIZED STORMS WITH ANY ACTIVITY
THAT CAN DEVELOP.  FURTHER STRENGTHENING OF THE LLJ WITH
ACCOMPANYING MOISTURE ADVECTION MAY SUPPORT WIDELY SCATTERED
THUNDERSTORMS SATURDAY NIGHT ACROSS PARTS OF THE SRN PLAINS...
POTENTIALLY REACHING SRN MO.

..PETERS.. 04/21/2006