SPC AC 261728
DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1228 PM CDT FRI JUN 26 2015
VALID 271200Z - 281200Z
...THERE IS A SLGT RISK OF SVR TSTMS ACROSS PORTIONS OF THE
MID-ATLANTIC REGION TO CENTRAL GEORGIA...
...THERE IS A SLGT RISK OF SVR TSTMS ACROSS THE RED RIVER VALLEY OF
THE NORTH...
...THERE IS A MRGL RISK OF SVR TSTMS ACROSS PORTIONS OF THE
MID-ATLANTIC TO THE SOUTHEAST UNITED STATES AND SOUTHERN GREAT
PLAINS...
...THERE IS A MRGL RISK OF SVR TSTMS ACROSS PARTS OF THE
NORTH-CENTRAL UNITED STATES...
...THERE IS A MRGL RISK OF SVR TSTMS ACROSS PORTIONS OF ARIZONA AND
NEW MEXICO...
...SUMMARY...
ISOLATED TO WIDELY SCATTERED SEVERE THUNDERSTORMS ARE POSSIBLE
SATURDAY AFTERNOON AND EVENING OVER PARTS OF THE MID-ATLANTIC REGION
TO CENTRAL GEORGIA...AND ALSO ACROSS PARTS OF THE RED RIVER VALLEY
OF THE NORTH.
...SYNOPSIS...
A MID-LEVEL CYCLONE WILL DEEPEN WHILE TRACKING ENEWD ACROSS PARTS OF
THE LOWER GREAT LAKES REGION...WITH THE SURROUNDING AREA OF CYCLONIC
FLOW AMPLIFYING ACROSS THE ERN CONUS. THE ASSOCIATED SFC CYCLONE
WILL TRACK NEWD ACROSS PARTS OF THE OH VALLEY REGION WHILE
OCCLUDING...AS WEAK SECONDARY CYCLOGENESIS POTENTIALLY TAKES PLACE
INVOF THE MID-ATLANTIC. THE ATTENDANT SFC WARM/MOIST SECTOR WILL
EDGE NWD ACROSS PARTS OF THE MID-ATLANTIC...WHILE A COLD FRONT ARCS
SWWD INTO THE SWRN/S-CNTRL STATES FROM THE EVOLVING CYCLONES. ON THE
WRN FRINGES OF AMPLIFYING MID-LEVEL CYCLONIC FLOW...A COMPACT VORT
MAX AND ASSOCIATED SPEED MAX WILL ADVANCE SEWD FROM THE SRN CANADIAN
PRAIRIE PROVINCES TO THE UPPER MS VALLEY...WITH AN ASSOCIATED SFC
TROUGH MOVING SEWD ACROSS THE RED RIVER VALLEY OF THE NORTH. EVEN
FARTHER W...A LARGE MID-LEVEL ANTICYCLONE WILL BE MAINTAINED OVER
THE WRN STATES...WITH MONSOON-RELATED MOISTURE AMIDST MODEST
MID-LEVEL ELYS BEING MAINTAINED ON ITS SRN FLANK ACROSS PARTS OF THE
SWRN STATES.
...PORTIONS OF THE MID-ATLANTIC REGION TO CENTRAL GEORGIA...
CYCLONIC H7-H5 FLOW OVER THE WARM/MOIST SECTOR WILL INTENSIFY TO
AROUND 30-40 KT IN RESPONSE TO THE AMPLIFICATION OF THE DEEP
CYCLONE. AMIDST GENERALLY POOR MID-LEVEL LAPSE RATES ASSOCIATED WITH
APPROACHING-MOIST-NEUTRAL THERMODYNAMIC PROFILES ALOFT...NEGLIGIBLE
CAPPING...AND RICH DEEP MOISTURE...TSTMS WILL LIKELY INCREASE IN
COVERAGE THROUGH THE DAY AHEAD OF THE COLD FRONT...AS POCKETS OF
INSOLATION FACILITATE DIURNAL DESTABILIZATION. DEEP SHEAR ASSOCIATED
WITH THE MODERATE MID-LEVEL FLOW WILL BE SUFFICIENT FOR CONVECTION
TO EVOLVE INTO SMALL...SUSTAINED...FORWARD-PROPAGATING MULTICELL
CLUSTERS CAPABLE OF ISOLATED TO WIDELY SCATTERED DMGG WIND GUSTS --
AIDED BY WATER-LOADING ASSOCIATED WITH 1.75-2.00-INCH PW. DEEP SHEAR
WILL BE STRONGEST ACROSS PARTS OF THE MID-ATLANTIC AND ESPECIALLY
INVOF THE NRN EXTENT OF THE NWD-ADVANCING WARM SECTOR...WHERE SFC
WINDS WILL BE LOCALLY BACKED/SELY-ELY ENHANCING LOW-LEVEL SRH. A FEW
TRANSIENT SUPERCELLS MAY EVOLVE IN THIS ENVIRONMENT...POTENTIALLY
CAPABLE OF A COUPLE OF BRIEF TORNADOES -- PARTICULARLY FROM PARTS OF
CNTRL/ERN/NRN VA INTO ADJACENT MD.
...PORTIONS OF THE DEEP SOUTH TO S-CNTRL TX...
MULTIPLE...LOOSELY ORGANIZED CLUSTERS OF TSTMS WILL LIKELY EVOLVE
ALONG THE FRONTAL ZONE AS MODERATE DESTABILIZATION OF THE MOIST PBL
OCCURS IN RESPONSE TO SFC HEATING. SPORADIC DMGG WIND GUSTS MAY
OCCUR IN THE HIGH-PW ENVIRONMENT SUPPORTING WATER LOADING. DEEP
SHEAR WILL BE RELATIVELY MORE MODEST TO THE SW OF THE SLIGHT-RISK
AREA...MITIGATING CONVECTIVE ORGANIZATION AND PRECLUDING A MORE
SUBSTANTIAL SVR RISK.
...THE RED RIVER VALLEY OF THE NORTH...
DESPITE ONLY MODEST LOW-LEVEL MOISTURE RETURN IN ADVANCE OF THE
SEWD-MOVING SFC TROUGH...THE PRESENCE OF MIDDLE/UPPER 50S DEWPOINTS
SHOULD BE SUFFICIENT FOR 750-1250 J/KG OF MLCAPE TO BECOME
ESTABLISHED DURING PEAK HEATING...AS MID-LEVEL LAPSE RATES STEEPEN
IN ADVANCE OF THE COMPACT MID-LEVEL VORT MAX/SPEED MAX. SFC
OBSERVATIONS WOULD SUGGEST THAT THE NAM FORECAST SOUNDINGS OFFER
TOO-RICH MOISTURE IN THE PBL...THOUGH EVEN THE MORE-STRONGLY MIXED
GFS SOLUTIONS SUGGEST AT LEAST MARGINAL DESTABILIZATION/MLCAPE.
TSTMS WILL LIKELY DEVELOP IN PROXIMITY TO THE SFC TROUGH AND
VORT-MAX/SPEED-MAX-PRECEDING ASCENT AROUND PEAK HEATING -- NEAR THE
INTERNATIONAL BORDER -- AND SPREAD SEWD/SSEWD. THE LATEST
MULTI-MODEL CONSENSUS SUGGESTS THAT 30-40 KT OF EFFECTIVE BULK SHEAR
WILL BE PRESENT TO SUPPORT ORGANIZED CONVECTIVE STRUCTURES/POSSIBLE
SUPERCELLS CAPABLE OF ISOLATED TO WIDELY SCATTERED SVR
WIND/HAIL...ESPECIALLY AS H7-H5 LAPSE RATES INCREASE TO AROUND 7
C/KM.
...PORTIONS OF THE SOUTHWEST...
THE INFLUX OF MONSOON-RELATED MOISTURE WILL ENCOURAGE TSTM
DEVELOPMENT DURING THE DAY AS TERRAIN-DRIVEN CIRCULATIONS BECOME
ENHANCED. LARGE DCAPE IN THE DEEPLY MIXED PBL WILL BE CAPABLE OF
SUPPORTING LOCALLY STRONG OUTFLOW WINDS...WITH A COUPLE OF SVR WIND
GUSTS POSSIBLE. SUCH RISK COULD INCREASE IN PARTS OF SRN/CNTRL
AZ...IF 10-20 KT OF H7-H5 ELYS WERE TO FACILITATE
FORWARD-PROPAGATING CONVECTIVE CLUSTERS MOVING WWD ACROSS THE DESERT
FLOOR INCLUDING THE TUCSON/PHOENIX AREAS AND VICINITY.
..COHEN.. 06/26/2015
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