SWODY1
SPC AC 202140
DAY 1 CONVECTIVE OUTLOOK RESENT 1
NWS STORM PREDICTION CENTER NORMAN OK
0440 PM CDT FRI JUL 20 2007
VALID 202000Z - 211200Z
..THERE IS A SLGT RISK OF SVR TSTMS ACROSS PARTS OF THE DEEP
SOUTH/SOUTHEAST/ERN NC...
..THERE IS A SLGT RISK OF SVR TSTMS OVER SERN AZ/EXTREME SWRN NM...
..CAROLINAS/SOUTHEAST...
DEEP-LAYER FRONTAL ZONE CONTINUES TO SURGE ACROSS ERN NC ATTM WITH
WEAK FRONTAL WAVE AIDING CONVECTIVE DEVELOPMENT ALONG THE COAST. A
SEGMENT OF THE FRONT ALSO APPEARS TO HAVE BEEN SLOWED/FRACTURED BY
THE HIGHER TERRAIN OF THE APPALACHIANS AND WAS LIKELY PROVIDING
IMPETUS FOR A CLUSTER OF STORMS NOW DEVELOPING ACROSS THE NC
PIEDMONT. YET ANOTHER INTERESTING MESOSCALE FRONTAL/TERRAIN-INDUCED
FEATURE APPEARS IN RADAR AND SATELLITE LOOPS ACROSS NWRN SC WHERE A
SMALL VORTEX WAS SPREADING EWD. LIFT ASSOCIATED WITH THIS IMPULSE
WILL LIKELY AID STRONG TO SEVERE STORM DEVELOPMENT ACROSS MUCH OF
CNTRL/ERN SC OVER THE NEXT FEW HOURS. FINALLY...LARGE TRAILING
STRATIFORM RAIN REGION/COLD POOL AND MESOSCALE ORGANIZATION WITH THE
MCS ACROSS GA/ERN AL WILL PROMOTE ADDITIONAL ROBUST CONVECTIVE
DEVELOPMENT ALONG THE LEADING EDGE OF THIS COMPLEX AS IT SETTLES
SSEWD ACROSS GA THROUGH THE REMAINDER OF THE AFTERNOON AND EARLY
EVENING.
DESPITE GENERALLY LIMITED SHEAR...DEGREE OF MESOSCALE
FORCING/ORGANIZATION...COUPLED WITH MAGNITUDE OF INSTABILITY...WILL
SUSTAIN THE THREAT FOR SCATTERED WIND DAMAGE EVENTS ACROSS THESE
AREAS FOR SEVERAL MORE HOURS. GREATEST DAMAGING WIND POTENTIAL
APPEARS TO EXIST WITH THE BOWING COMPLEX OF STORMS MOVING INTO VERY
UNSTABLE AIR SITUATED OVER SERN GA/SWRN SC OVER THE NEXT FEW HOURS.
..TN VALLEY TO LOWER MS VALLEY/OZARKS...
RELATIVE MINIMUM IN CONVECTIVE ACTIVITY EXISTS ACROSS NRN AL ATTM IN
THE WAKE OF EARLIER MCS NOW OVER ERN AL/GA. HOWEVER...FLANKING
PORTION OF THE MCS OUTFLOW FROM NW AL ACROSS NRN MS...AND
OUTFLOW/FRONT INTERSECTION ACROSS NERN MS...HAVE RECENTLY AIDED
STRONG TO SEVERE STORM DEVELOPMENT. AIR MASS TO THE SOUTH OF THIS
ONGOING ACTIVITY IS VERY UNSTABLE WITH MLCAPE OF OVER 2000 J/KG
EXTENDING SOUTH ACROSS MS AND WEST ACROSS AR TO THE OZARKS.
DEEP-LAYER NNWLY FLOW ON THE SWRN PERIPHERY OF THE LARGE SCALE
TROUGH DOES TEND TO WEAKEN WITH WWD EXTENT ACROSS THIS PORTION OF
THE FRONTAL ZONE. IN ADDITION...WARMER TEMPERATURES ALOFT MAY TEND
TO INHIBIT STRONGER UPDRAFTS. HOWEVER...RECENT STORM MERGERS AND
POTENTIAL FOR DEEPENING COLD POOL ACROSS PARTS OF NERN MS MAY
PROMOTE SOME UPSCALE GROWTH AND AN INCREASING THREAT OF DAMAGING
WIND EVENTS ALONG THE MS/AL BORDER AREA NEXT FEW HOURS. FARTHER
WEST...STRONG BOUNDARY LAYER HEATING HAS CONTRIBUTED TO AN AXIS OF
GREATER DCAPE FROM MS WNWWD ACROSS AR. SCATTERED STORMS ALONG THIS
AXIS COULD ALSO PRODUCE DAMAGING WINDS IN NEXT FEW HOURS.
..SOUTHWEST...
STORMS ARE ERUPTING ACROSS THE WHITE AND CHIRICAHUA MOUNTAINS OF ERN
AZ WITHIN WEAKLY CAPPED UNSTABLE REGIME. A CHANNEL OF DEEP LAYER ELY
FLOW EXISTS AHEAD OF A WWD-MOVING UPPER VORTEX OVER NM. THIS FEATURE
SHOULD ENHANCE BOTH LARGE SCALE ASCENT AND BULK SHEAR ACROSS SRN AZ
THROUGH THE EVENING. FURTHERMORE...STRONG DOWNSTREAM HEATING AND
DESTABILIZATION WILL PROMOTE UPSCALE CONVECTIVE DEVELOPMENT AS
ORGANIZED MULTICELLULAR STORMS AND OUTFLOWS SPREAD SWD/SWWD OFF THE
HIGHER TERRAIN AND LIKELY SPUR ADDITIONAL DEVELOPMENT. HIGH WINDS
AND HAIL SHOULD ACCOMPANY A FEW OF THE MORE INTENSE/LONG-LIVED
UPDRAFTS.
..MT/WY...
BELT OF STRONG SWLY FLOW EXISTS ATOP WARM AND UNSTABLE...BUT
CAPPED...AIR MASS OVER WRN/CNTRL MT ATTM. WATER VAPOR IMAGERY AND
SHORT-TERM MODEL GUIDANCE SUGGEST LARGER SCALE FORCING FOR ASCENT
ACROSS THE REGION WILL REMAIN WEAK/NEUTRAL THROUGH THIS EVENING.
HOWEVER...EFFECTS OF DIABATIC AND OROGRAPHIC FORCING MAY BE
SUFFICIENT FOR ISOLATED TSTM DEVELOPMENT AS INHIBITION IS LOCALLY
OVERCOME/ELIMINATED. IF STORMS CAN FORM...BOTH SHEAR AND INSTABILITY
WILL SUPPORT SUPERCELL POTENTIAL WITH ATTENDANT THREATS OF SEVERE
HAIL/WIND. WEAKER SHEAR BUT STRONGER INSTABILITY ACROSS MUCH OF WY
WILL LIMIT MORE WIDESPREAD SEVERE HERE BUT A FEW MULTICELL STORMS
COULD ATTAIN SEVERE LEVELS INTO THE EVENING.
GIVEN CURRENT SITUATION WITH RESPECT TO LARGE SCALE FORCING AND
CAP...WILL MAINTAIN A CONDITIONAL LOW PROBABILITY OF SEVERE WEATHER
ACROSS PARTS OF MT/WY THROUGH THIS EVENING.
.CARBIN.. 07/20/2007
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