DAY1SVR: Day 1 Convective Outlook

ACUS01 KWNS 201959
SWODY1
SPC AC 201957

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0257 PM CDT MON MAY 20 2013

VALID 202000Z - 211200Z

...THERE IS A MDT RISK OF SVR TSTMS OVER NORTH CENTRAL
TX...CENTRAL/ERN OK...EXTREME SERN KS...SRN MO...AND NWRN AR...

...THERE IS A SLGT RISK OF SVR TSTMS FROM THE SRN PLAINS INTO THE
GREAT LAKES REGION...

...SRN PLAINS INTO THE OZARKS...
MINOR ADJUSTMENTS HAVE BEEN MADE TO THE OUTLOOK BASED ON CURRENT
BOUNDARY LOCATIONS AND RECENT CONVECTIVE INITIATION.

SEVERE STORMS HAVE DEVELOPED ALONG THE DRY LINE FROM THE WRN PART OF
NORTH TEXAS INTO CENTRAL OK...WITH ADDITIONAL STORMS OVER SERN KS
AND SWRN MO. SPECIAL SOUNDINGS AT 17-18Z FROM OUN/SGF/FWD INDICATE
STEEP LAPSE RATES ARE PERSISTING ABOVE 850 MB THAT ARE ASSOCIATED
WITH THE ELEVATED MIXED LAYER ACROSS THE REGION. WITH SURFACE
DEWPOINTS IN THE UPPER 60S/LOWER 70S AND TEMPERATURES WARMING INTO
THE LOW/MID 80S IN OK AND NEAR 90 IN NRN TX...A VERY UNSTABLE
ENVIRONMENT IS PRESENT WITH SBCAPE RANGING FROM 3500-5000 J/KG. DEEP
LAYER SHEAR OF 40-50 KT WILL ENHANCE STORM ORGANIZATION AND
INTENSITY WITH POTENTIAL FOR SUPERCELLS AND BOWING LINE SEGMENTS.
VERY LARGE HAIL...DAMAGING WIND AND SEVERAL STRONG TORNADOES WILL BE
POSSIBLE THROUGH THE EVENING AS ACTIVITY CONTINUES TO DEVELOP AND
SPREAD EWD/NEWD.

...GA/FL...
STRONGER STORMS APPEAR MOST LIKELY FROM SRN GA AND NRN FL INTO THE
SWRN PART OF THE FL PENINSULA...IN ASSOCIATION WITH AN UPPER LOW
OVER SRN GA/NRN FL. ISOLATED MARGINAL HAIL AND WET MICROBURSTS MAY
ACCOMPANY A FEW OF THE CELLS BUT OVERALL SEVERE THREAT SHOULD BE
LIMITED.

..WEISS.. 05/20/2013

.PREV DISCUSSION... /ISSUED 1130 AM CDT MON MAY 20 2013/

...SRN PLAINS TO OZARK PLATEAU...
OVERALL FORECAST SCENARIO REMAINS SIMILAR TO EARLIER OUTLOOKS WITH
ONLY MINOR OVERALL CHANGES TO INDIVIDUAL HAZARD PROBABILITIES.
MID-LEVEL SPEED MAX /65 KT AT 500 MB IN THE 12Z ABQ RAOB/ ATTENDANT
TO THE SHORTWAVE IMPULSE OVER THE LEE OF THE SRN ROCKIES WILL
OVERSPREAD MOST OF OK TO THE LOWER MO VALLEY BY EARLY EVENING.
TRAILING PORTION OF COLD FRONT HAS BECOME SLOW-MOVING FROM SERN KS
TO SWRN OK...INTERSECTING A DRYLINE THAT WILL BECOME WELL
ESTABLISHED S/SWWD ACROSS THE TX BIG COUNTRY TO THE ERN EDWARDS
PLATEAU BY LATE AFTERNOON. SCATTERED TSTMS WILL INITIATE ALONG THESE
BOUNDARIES BY MID-AFTERNOON. MORNING CONVECTION-ALLOWING MODEL
GUIDANCE ARE INSISTENT THAT THIS ACTIVITY WILL RAPIDLY GROW UPSCALE
INTO NUMEROUS LINE SEGMENTS...SURGING EWD THIS EVENING WITHIN A
STRONGLY UNSTABLE ENVIRONMENT.

INITIAL TSTMS WILL BECOME SUPERCELLUAR QUICKLY WITH VERY LARGE HAIL
LIKELY AS HODOGRAPHS/INSTABILITY WILL BE QUITE FAVORABLE...ALONG
WITH A FEW TORNADOES. THE GREATEST RISK FOR A COUPLE OF STRONG
TORNADOES SHOULD EXIST FROM S-CNTRL INTO E-CNTRL OK. BUT WITH
PREDOMINANT SWLY COMPONENT TO LOW-LEVEL FLOW AND MODERATE 0-1 KM
SHEAR...OVERALL TORNADO INTENSITY/LONGEVITY MAY BE
TEMPERED...ESPECIALLY WITH CONVECTION EXPECTED TO GROW UPSCALE SO
QUICKLY. NEVERTHELESS...THIS GROWTH SHOULD YIELD BOWING LINEAR
SEGMENTS CAPABLE OF SWATHS OF WIDESPREAD DAMAGING WINDS...LARGE HAIL
AND A FEW TORNADOES.

...MID/UPPER-MS VALLEY TO CNTRL GREAT LAKES...
PRIMARY CHANGE HAS BEEN TO EXPAND DAMAGING WIND PROBABILITIES E/NEWD
FOR THIS AFTERNOON AND EVENING. IN THE WAKE OF CONVECTION
YESTERDAY...LOW-LEVEL MOISTURE PLUME HAS BECOME CONFINED FROM LOWER
MI S/SSWD TO THE CONFLUENCE OF THE MS/OH RIVERS. BUT PLENTIFUL
HEATING IS OCCURRING TO THE N OF THIS PLUME WILL YIELD A RECOVERING
AIR MASS DOWNSTREAM OF A TSTM CLUSTER APPROACHING CNTRL MO. THIS
ACTIVITY SHOULD GROW UPSCALE ALONG THE EDGE OF THE INSTABILITY
AXIS...WITH ADDITIONAL LINEAR SEGMENTS EMANATING E/NEWD FROM THE
OZARK PLATEAU LATER TODAY. SWATHS OF DAMAGING WINDS...LARGE HAIL AND
A COUPLE OF TORNADOES WILL BE POSSIBLE.

FARTHER N/NW...SCATTERED TSTMS ARE EXPECTED TO FORM OVER LOWER MI
AND IN PARTS OF THE UPPER MIDWEST IN ASSOCIATION WITH AN UPPER-LEVEL
LOW CENTERED OVER ERN SD. BUOYANCY WILL BE STRONGEST OVER LOWER MI
WITHIN THE LOW-LEVEL MOISTURE PLUME CHARACTERIZED BY MIDDLE TO UPPER
60S SURFACE DEW POINTS. IN THE UPPER MIDWEST...POCKETS OF ROBUST
SURFACE HEATING WILL SUPPORT AT LEAST MODEST INSTABILITY AND WITH
STRONG UNIDIRECTIONAL WIND PROFILES...SETUP COULD A FEW ORGANIZED
TSTM CLUSTERS. A MIX OF ISOLATED SEVERE HAIL/WIND SHOULD BE THE
PRIMARY THREATS.

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