[SWODY1] SWODY1

[Severe Weather Outlook Day 1]

ACUS01 KWNS 220554
SWODY1
SPC AC 220552

DAY 1 CONVECTIVE OUTLOOK  
NWS STORM PREDICTION CENTER NORMAN OK
1252 AM CDT SAT JUL 22 2006

VALID 221200Z - 231200Z

...THERE IS A SLGT RISK OF SVR TSTMS FROM PORTIONS OF THE NERN
STATES THROUGH THE MID ATLANTIC...SERN STATES...LOWER MS VALLEY AND
SERN TX...

...SYNOPSIS...

SYNOPTIC PATTERN WILL REMAIN DOMINATED BY AN UPPER TROUGH OVER THE
OH VALLEY AND GREAT LAKES WITH A CLOSED UPPER RIDGE IN THE W. SERIES
OF VORTICITY MAXIMA WILL ROTATE THROUGH THE UPPER TROUGH. ONE SUCH
FEATURE NOW MOVING THROUGH THE BASE OF THE TROUGH AND INTO THE OH
VALLEY WILL CONTINUE ENEWD INTO THE NERN STATES SATURDAY AFTERNOON.
A SURFACE LOW WILL ACCOMPANY THE VORT MAX AND IS FORECAST TO UNDERGO
SOME DEEPENING AS IT TRACKS NEWD ALONG THE SURFACE FRONT INTO PA BY
AFTERNOON. NERN PORTION OF THIS FRONT WILL MOVE VERY LITTLE OR LIFT
SLOWLY NWD...WHILE THE SWRN PORTIONS WILL CONTINUE SWD THROUGH THE
SERN STATES AND S TX.


...MID ATLANTIC THROUGH SRN NEW ENGLAND...

RICH LOW LEVEL MOISTURE EXISTS IN THE PRE-FRONTAL WARM SECTOR WITH
DEWPOINTS IN THE LOWER 70S. PRIMARY CONCERN IS HOW SEVERAL MCSS NOW
ONGOING FROM THE CNTRL APPALACHIANS WWD INTO THE OH VALLEY WILL
EVOLVE. COLD POOL FROM MCS NOW ONGOING FROM WV SWD THROUGH WRN NC
WAS APPARENTLY DEEP AND STRONG ENOUGH TO CROSS THE MOUNTAINS WITH
NEW STORMS CONTINUING TO DEVELOP ALONG THE LEADING OUTFLOW. MUCH OF
THE ATMOSPHERE IN THIS REGION HAS NOT BEEN OVERTURNED AND THERE IS
CONCERN THAT STORMS MAY CONTINUE DEVELOPING INTO MUCH OF THE
NIGHT...ESPECIALLY FROM VA SWD. MUCH OF THIS CONVECTION SHOULD
REMAIN S OF THE MID ATLANTIC AND NERN STATES...BUT DEBRIS FROM
UPSTREAM STORMS CURRENTLY OVER THE OH VALLEY COULD ALSO SERVE TO
LIMIT HEATING AND INSTABILITY. WHERE POCKETS OF SURFACE HEATING DO
DEVELOP...MLCAPE FROM 1000 TO 1500 J/KG WILL BE POSSIBLE GIVEN THE
RICH LOW LEVEL MOISTURE IN PLACE.

LOW LEVEL JET WILL STRENGTHEN WITHIN ZONE OF ASCENT AND HEIGHT FALLS
E OF SURFACE LOW FROM NRN VA THROUGH ERN PA AND SRN NEW ENGLAND AS
THE SHORTWAVE TROUGH ADVANCES EWD DURING THE DAY. THE STRENGTHENING
LOW LEVEL WIND FIELDS AND MID LEVEL JET ACCOMPANYING THE SHORTWAVE
TROUGH WILL CONTRIBUTE TO FAVORABLE KINEMATIC PROFILES FOR ORGANIZED
STORM STRUCTURES INCLUDING SUPERCELLS AND BOW ECHOES. LOW LEVEL
STORM RELATIVE HELICITY FROM 200 TO 300 M2/S2 WILL POSE A THREAT FOR
LOW LEVEL MESOCYCLONES AND TORNADOES WITH ANY DISCRETE STORM
STRUCTURES. OTHERWISE DAMAGING WIND WILL BE POSSIBLE. HIGHER END
SEVERE THREAT IS CONDITIONAL ON DEGREE OF INSTABILITY AND HOW MUCH
ONGOING CONVECTION CONTAMINATES THE WARM SECTOR. WILL KEEP THIS AREA
IN SLIGHT RISK FOR NOW DUE TO THE POTENTIAL LIMITING FACTOR.
HOWEVER...AN UPGRADE TO MODERATE RISK MIGHT BE NEEDED IN LATER
OUTLOOKS ONCE IT BECOMES CLEAR IF AND WHERE SUFFICIENT
DESTABILIZATION WILL OCCUR.

...CAROLINAS THROUGH THE SERN STATES AND SERN TX...

POSSIBILITY REMAINS THAT MCS NOW CROSSING THE APPALACHIANS WILL
CONTINUE INTO THE MORNING...EXHAUSTING MUCH OF THE INSTABILITY AND
REDUCING THE SEVERE THREAT OVER THE CAROLINAS. WILL LEAVE A SLIGHT
RISK FOR NOW IN CASE THIS SCENARIO DOES NOT PLAY OUT AND THE
ATMOSPHERE IS ABLE TO RECOVER. WEAK VERTICAL WIND PROFILES WILL
SUPPORT MULTICELL STORMS IN PRE-FRONTAL WARM SECTOR WITH A THREAT
FOR MAINLY ISOLATED DAMAGING WIND.

FARTHER SW FROM GA THROUGH THE LOWER MS VALLEY AND S TX...MORE
ABUNDANT SURFACE HEATING SHOULD ALLOW THE ATMOSPHERE TO BECOME
MODERATELY UNSTABLE. SCATTERED MULTICELL STORMS WILL LIKELY
INTENSIFY ALONG AND AHEAD OF THE FRONT DURING THE AFTERNOON WITH A
THREAT FOR ISOLATED DAMAGING WIND GUSTS THROUGH MID EVENING.

...WI...

A SHORTWAVE TROUGH WILL DROP SWD INTO THE UPPER MS VALLEY AND WRN
GREAT LAKES AREA DURING THE DAY. RELATIVELY COOL MID LEVEL
TEMPERATURES (-12C AT 500 MB) AND STRONG SURFACE HEATING WILL
CONTRIBUTE TO STEEP LAPSE RATES AND MLCAPE AROUND 1000 J/KG. AS THE
ATMOSPHERE DESTABILIZES...STORMS WILL LIKELY DEVELOP DURING THE
AFTERNOON WITHIN ZONE OF ASCENT ASSOCIATED WITH THE SERN MOVING
IMPULSE. THE THERMODYNAMIC ENVIRONMENT SUGGEST A FEW STORMS COULD
PRODUCE GUSTY WINDS AND HAIL THROUGH EARLY EVENING.

..DIAL/CROSBY.. 07/22/2006