DAY1SVR: Day 1 Convective Outlook

ACUS01 KWNS 201955
SWODY1
SPC AC 201953

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0253 PM CDT MON AUG 20 2012

VALID 202000Z - 211200Z

...THERE IS A SLGT RISK OF SVR TSTMS ACROSS THE SRN HIGH PLAINS...

HAVE OPTED TO LOWER SEVERE PROBS ACROSS PORTIONS OF THE NRN FL
PENINSULA DUE PRIMARILY TO MCS SEWD PROPAGATION AND CONVECTIVE
OVERTURNING ACROSS THIS REGION. WHILE A FEW STORMS MAY ULTIMATELY
PRODUCE GUSTY WINDS AS THE SW-NE ORIENTED COMPLEX DRIFTS SEWD IT
DOES NOT APPEAR TO BE A SIGNIFICANT SEVERE THREAT THE REST OF THE
PERIOD.

ELSEWHERE...EARLIER THOUGHTS REGARDING SEVERE POTENTIAL ACROSS THE
SRN HIGH PLAINS REMAIN. CONVECTION IS GRADUALLY INCREASING ACROSS
THE HIGHER TERRAIN OF LAS ANIMAS/COLFAX COUNTIES ALONG THE CO/NM
BORDER. THIS ACTIVITY SHOULD INCREASE IN INTENSITY/COVERAGE AS IT
SPREADS/DEVELOPS ACROSS NERN NM INTO THE WRN TX PANHANDLE THIS
EVENING.

..DARROW.. 08/20/2012

.PREV DISCUSSION... /ISSUED 1111 AM CDT MON AUG 20 2012/

...SYNOPSIS...

LONGWAVE TROUGH EXTENDING FROM JAMES BAY THROUGH THE LOWER MS VALLEY
WILL BEGIN TO SHIFT EWD IN RESPONSE TO THE SLOW EWD DEVELOPMENT OF
UPSTREAM RIDGE AXIS ACROSS THE HIGH PLAINS...AND THE ONSHORE
MOVEMENT OF NEXT TROUGH ONTO THE PACIFIC NW COAST. WITHIN THIS
BROAD-SCALE PATTERN...A VORTICITY MAXIMUM OVER MS/LA WILL WEAKEN
TODAY WHILE PROGRESSING INTO AN INCREASINGLY CONFLUENT REGIME OVER
THE SERN ATLANTIC COAST. THIS FEATURE WILL BE FOLLOWED BY A MORE
SIGNIFICANT PERTURBATION MOVING SEWD FROM THE OZARK PLATEAU THROUGH
THE LOWER MS VALLEY AND CNTRL GULF STATES. FARTHER W...A VORTICITY
MAXIMUM CURRENTLY CRESTING THE RIDGE AXIS OVER THE ERN GREAT
BASIN/CNTRL ROCKIES WILL BEGIN TO AFFECT THE CNTRL/SRN HIGH PLAINS
LATER TODAY INTO TONIGHT.

IN THE LOW LEVELS...A DIFFUSE FRONT FROM THE COASTAL CAROLINAS SWWD
ACROSS THE GULF COAST STATES WILL SETTLE SLOWLY SWD WHILE A LEE
TROUGH BECOMES BETTER DEFINED OVER THE HIGH PLAINS.

...SRN HIGH PLAINS THIS AFTERNOON AND EVENING...

12Z ABQ/AMA/MAF SOUNDINGS AND SATELLITE-DERIVED PW DATA INDICATE
THAT A MODESTLY-MOIST /I.E. PW VALUES OF AROUND ONE INCH/ AIR MASS
RESIDES ACROSS THE REGION...COINCIDENT WITH ERN EXTENSION OF
EML/STEEP MIDLEVEL LAPSE RATE PLUME. WHEN COUPLED WITH DAYTIME
HEATING...ENVIRONMENT IS EXPECTED TO BECOME MODERATELY UNSTABLE BY
AFTERNOON WITH MLCAPE APPROACHING 1000-1500 J/KG. THE AUGMENTATION
OF OROGRAPHIC UPLIFT BY FORCING FOR ASCENT/DCVA ASSOCIATED WITH
VORTICITY MAXIMUM MENTIONED IN SYNOPSIS IS EXPECTED TO GIVE RISE TO
WIDELY SCATTERED TSTMS THIS AFTERNOON WITHIN A KINEMATIC SETTING
FEATURING 30-40 KT OF DEEP...NWLY SHEAR. AS SUCH...THE POTENTIAL
WILL EXIST FOR SUPERCELLS AS THE INITIAL STORM MODE WITH THE PRIMARY
HAZARD BEING LARGE HAIL. UPSCALE GROWTH INTO AN MCS APPEARS
PROBABLE BY LATE EVENING INTO TONIGHT WITH A LOCAL WIND/HAIL THREAT
DEVELOPING SEWD INTO WRN TX.

...CNTRL/ERN GULF COAST AND FL THIS AFTERNOON THROUGH TONIGHT...

DIFFERENTIAL HEATING ZONE DEVELOPING ACROSS SRN GA/NRN FL AND
EVOLVING SEA BREEZE FRONTS ARE EXPECTED TO SERVE AS THE FOCI FOR
TSTM DEVELOPMENT THIS AFTERNOON WITHIN A MOIST...BUT WEAK LAPSE RATE
ENVIRONMENT WITH MLCAPE APPROACHING 1500-2500 J/KG. THIS
INSTABILITY RESIDES ON THE SRN FRINGE OF STRONGER MID AND HIGH-LEVEL
WIND FIELD...YIELDING SUFFICIENT VERTICAL SHEAR FOR TRANSIENT
SUPERCELL STRUCTURES AND DOWNSHEAR COLD POOL ELONGATION/FORWARD
PROPAGATION. WHILE LOCALLY DAMAGING WINDS WILL BE THE PRIMARY
HAZARD...A BRIEF TORNADO IS ALSO POSSIBLE.

A RENEWAL IN TSTM COVERAGE AND VIGOR MAY OCCUR OVERNIGHT ACROSS THE
FL PNHDL INTO BIG BEND AREA IN RESPONSE TO APPROACH OF VORTICITY
MAXIMUM THROUGH THE CNTRL GULF STATES AND ASSOCIATED WEAK
CYCLOGENESIS. MODEST VERTICAL SHEAR AND INSTABILITY MAY PROMOTE A
FEW ORGANIZED/MARGINALLY SEVERE STORMS INTO TUESDAY MORNING.

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