DAY1SVR: Day 1 Convective Outlook

ACUS01 KWNS 041558
SWODY1
SPC AC 041557

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1057 AM CDT SAT MAY 04 2013

VALID 041630Z - 051200Z

...NO SVR TSTM AREAS FORECAST...

...SYNOPSIS...
BLOCKY PATTERN WILL PERSIST...WITH THE MAIN BELT OF THE WLYS
CONTINUING ACROSS CNTRL CANADA...N OF BLOCKING HIGHS OVER THE NE
PACIFIC AND SRN ONT/QUE. S OF THE BLOCKS...NW AR UPR LOW SHOULD EDGE
SLOWLY SE THROUGH THE PERIOD...WHILE WEAKER SYSTEM NOW OVER SRN ID
RETROGRESSES SW TO NRN CA.

WITH CP OR MP AIR DOMINATING AT LWR LVLS...AND DEEP SHEAR REMAINING
WEAK OVER MOST AREAS...SVR TSTM RISK WILL REMAIN LOW. THE EXCEPTION
MAY BE OVER PARTS OF ERN FL...NEAR A WEAK W-E FRONT.
ELSEWHERE...ISOLD TSTMS MAY OCCUR OVER PARTS OF THE WEST AND THE
MID/UPR MS VLYS...MAINLY THIS AFTN/EVE.

...ERN FL THIS AFTN...
SATELLITE DATA AND SFC ANALYSIS SHOWS AN ELONGATED SFC LOW CENTERED
NEAR ORLANDO ATTM. THE LOW SHOULD REMAIN MORE OR LESS STNRY TODAY AS
WEAKER/SHALLOWER CIRCULATION NOW APPROACHING THE NERN GULF CSTL
WATERS IS ABSORBED WITHIN IT. E OF THE LOW...A NNW-SSE ORIENTED BAND
OF CONFLUENCE IS EXPECTED TO PERSIST OVER THE CSTL WATERS FROM THE
BAHAMAS TO NEAR JACKSONVILLE.

SFC HEATING OF MOIST...MODERATELY UNSTABLE ENVIRONMENT /SBCAPE
1500-2000 J PER KG AND PW AOA 1.25 INCHES/...AND WEAK LOW-LVL
CONVERGENCE...MAY YIELD A FEW AFTN TSTMS INVOF CNTRL FL SFC
LOW...AND PERHAPS NEAR CONFLUENCE ZONE GRAZING THE NE/E CNTRL FL
CST. HOWEVER...NEITHER DEEP SHEAR NOR MID LVL-LAPSE RATES WILL BE
NOTEWORTHY...AND LARGE SCALE FORCING FOR ASCENT APPEARS MINIMAL. ELY
COMPONENT TO LOW-LVL FLOW NEAR SFC LOW WILL LENGTHEN LOW-LVL
HODOGRAPHS AND CONTRIBUTE TO A CONDITIONAL RISK FOR A TORNADO WITH
ANY SUSTAINED STORMS THAT DO FORM...BUT OVERALL SVR RISK APPEARS
LOW.

...FAR ERN AR/NRN MS/W TN THIS AFTN...
SFC DATA SHOW A DEFORMATION ZONE/COLD FRONT EVOLVING ATTM IN AN ARC
EXTENDING FROM ERN AR ACROSS SRN AR INTO NE TX. THIS FEATURE LIKELY
IS FORMING IN RESPONSE TO VORT MAX ROTATING INTO SW QUADRANT OF AR
UPR LOW /PER SATELLITE/. STRONG SFC HEATING AND DCVA IN DRY SLOT OF
THE LOW MAY SUPPORT SCTD CONVECTIVE DEVELOPMENT AND PERHAPS AN ISOLD
LIGHTNING STRIKE OR TWO ALONG THE BOUNDARY AS IT MOVES INTO ERN
AR/NRN MS/W TN LATER TODAY. SHALLOW NATURE OF UNSTABLE LAYER AND
SPARSE BOUNDARY LAYER MOISTURE SHOULD LIMIT RISK FOR MORE WIDESPREAD
THUNDER.

..CORFIDI/BUNTING.. 05/04/2013

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