DAY1SVR: Day 1 Convective Outlook

ACUS01 KWNS 260055
SWODY1
SPC AC 260053

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0753 PM CDT THU APR 25 2013

VALID 260100Z - 261200Z

...NO SVR TSTM AREAS FORECAST...

...SYNOPSIS...
SOMEWHAT LESS-AMPLIFIED AND MORE PROGRESSIVE SYNOPTIC PATTERN IS
UNDERWAY OVER CONUS...COMPARED TO PREVIOUS DAYS. TROUGH NOW
EXTENDING FROM LH-AREA 500-MB LOW SWD ACROSS CENTRAL/SRN
APPALACHIANS IS EXPECTED TO MOVE OFFSHORE MOST OF ATLC COAST BY
12Z...EXCEPT FOR NEW ENGLAND. PERTURBATION THAT WAS OFFSHORE SRN CA
YESTERDAY AS CLOSED LOW CONTINUES TO DEAMPLIFY GRADUALLY AS IT
CROSSES AZ. THIS FEATURE SHOULD PROCEED ENEWD ACROSS ERN AZ AND
4-CORNERS REGION DURING NEXT FEW HOURS...REACHING CENTRAL/SRN
ROCKIES BY END OF PERIOD.

AT SFC...WAVY AND GENERALLY QUASISTATIONARY FRONTAL ZONE WAS DRAWN
AT 23Z FROM JUST OFFSHORE SRN NC AND SC THROUGH FRONTAL-WAVE LOW SE
CHS...SWWD ACROSS SRN GA AND CENTRAL FL PANHANDLE...N-CENTRAL AND
NWRN GULF OFFSHORE TX COAST.

...NRN OK/SRN KS AREA...
TSTMS STILL ARE EXPECTED TO DEVELOP LATE THIS EVENING AND INCREASE
IN COVERAGE TO SCATTERED LEVELS OVERNIGHT...WHILE SHIFTING GENERALLY
EWD TO ENEWD ACROSS THIS AREA. ACTIVITY WILL BE SUPPORTED BY
ELEVATED LOW-LEVEL WAA AND ROOTED IN RELATIVELY MOIST LAYER AROUND
750 MB...BASED ON 00Z FWD/OUN RAOBS AND TIME SERIES OF MODIFIED FCST
SOUNDINGS. OBSERVATIONAL RETURN-FLOW DATA...INCLUDING ANIMATIONS OF
UPSTREAM GPS PW OBS ACROSS TX AND SFC OBS OF MORE MEAGER THAN
PROGGED DEW POINTS...SUGGEST SOME DELAY IN PERIOD OF GREATEST
CONVECTIVE COVERAGE. ELEVATED MUCAPE AROUND 750 J/KG STILL IS
EXPECTED 09Z-12Z...LIMITED IN PART BY LACK OF MORE ROBUST 600-800 MB
LAYER LAPSE RATES. MAINLY...KINEMATIC SUPPORT THROUGH CLOUD-BEARING
LAYER WILL BE WEAK...WITH EFFECTIVE SHEAR MAGNITUDES ONLY AROUND
20-25 KT IN FCST SOUNDINGS. LATTER FACTOR...ALONG WITH LACK OF BOTH
GREATER BUOYANCY AND UPPER-LEVEL SUPPORT BENEATH SHORTWAVE RIDGING
ALOFT...SUGGEST THAT POTENTIAL FOR HAIL NEAR SVR LIMITS IS NON-ZERO
BUT TOO SMALL/ISOLATED TO MAINTAIN AOA 5% UNCONDITIONAL LINE.

...FAR W TX...
ISOLATED STG TSTMS...ORIGINATING IN AREAS OF OROGRAPHIC LIFT AND
EARLIER HEATING OF HIGHER TERRAIN OVER MEX...WILL BE CROSSING RIO
GRANDE AND MAY PERSIST DURING NEXT 1-2 HOURS ACROSS PORTIONS FAR W
TX. RAOBS BRACKETING THIS REGION -- ELP/DRT/MAF AND IN CHIHUAHUA --
APPEAR UNREPRESENTATIVE OF ENVIRONMENT SUPPORTING THAT CONVECTION.
ACTIVITY SHOULD MOVE EWD OVER RELATIVELY MOISTURE-DEPRIVED AIR MASS
WITH WHATEVER MLCAPE IS AVAILABLE DECREASING SUBSTANTIALLY AFTER
DARK. HOWEVER...IN MEANTIME...DRY SUBCLOUD LAYERS EVIDENT VIA SFC
CHARTS AND MODIFIED MODEL SOUNDINGS MAY FOSTER OCNL GUSTS OR HAIL
APCHG SVR LIMITS FROM MOST INTENSE DOWNDRAFTS.

..EDWARDS.. 04/26/2013

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