DAY1SVR: Day 1 Convective Outlook

ACUS01 KWNS 281632
SWODY1
SPC AC 281630

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1130 AM CDT MON MAY 28 2012

VALID 281630Z - 291200Z

...THERE IS A SLGT RISK OF SVR TSTMS FROM MN ACROSS THE GREAT LAKES
TO MI/IND...

...THERE IS A SLGT RISK OF SVR TSTMS OVER THE NORTHEAST...

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

...WI/ERN IA ACROSS IL TO MI...
A BAND OF WEAK PRE-FRONTAL TSTMS CONTINUES TO MOVE EAST INTO IL LATE
THIS MORNING WHILE PRIMARY COLD FRONT AND SURFACE LOW REMAIN TO THE
WEST...ACROSS WI/IA. WHILE ONGOING CONVECTION MAY TEND TO INCREASE
IN INTENSITY AS GREATER WARM SECTOR INSTABILITY IS
REALIZED...GREATER SHEAR AND FORCING WILL LIKELY EVOLVE ALONG OR
IMMEDIATELY AHEAD OF THE COLD FRONT. RENEWED STORM DEVELOPMENT IS
ANTICIPATED ALONG THE COLD FRONT AND NEAR SURFACE LOW...FROM WI TO
ERN IA...THIS AFTERNOON. THIS IS WHERE MLCAPE VALUES OF 1000-1800
J/KG WILL BE REACHED AMIDST RELATIVELY WEAK INHIBITION. LIFT ALONG
THE FRONT WILL BE AIDED BY STRONG HEIGHT FALLS ACROSS THE REGION AND
THESE FACTORS SHOULD SUSTAIN STRONG TO SEVERE STORMS SPREADING
EAST/SOUTHEAST LATER TODAY.

DEEP-LAYER SHEAR AROUND 40KT WILL SUPPORT ORGANIZED STORM
MODES...INCLUDING SUPERCELLS AND BOWING STRUCTURES CAPABLE OF MAINLY
DAMAGING WINDS AND LARGE HAIL. GIVEN LINEAR FORCING ALONG THE
ADVANCING FRONT...STORMS MAY MERGE INTO A RELATIVELY EXTENSIVE
SQUALL LINE BY LATE AFTERNOON INTO THIS EVENING. BOWING LINE
SEGMENTS WILL BE QUITE CAPABLE OF PRODUCING DAMAGING WINDS FROM ERN
WI AND NRN IL ACROSS LAKE MI AND INTO MI THROUGH THE EVENING.

...MN TO NRN WI...
A SECONDARY FRONTAL SURGE ASSOCIATED WITH ANOTHER STRONG VORT LOBE
ROTATING THROUGH THE UPPER LOW OVER ND WILL SPREAD EAST ACROSS
NRN/CNTRL MN THROUGH THE AFTERNOON. DESPITE HAVING ALREADY
EXPERIENCED SOME CONVECTIVE OVERTURNING WITH THE DEEP CONVECTION
ASSOCIATED WITH THE LEADING FRONT ACROSS SRN/CNTRL MN LAST
NIGHT...AIRMASS AHEAD OF THIS SECOND FRONT SHOULD DESTABILIZE
SUFFICIENTLY TO SUPPORT STRONGER STORM UPDRAFTS WITH HAIL AND HIGH
WIND POTENTIAL. LATEST GUIDANCE SUGGEST THIS ACTIVITY WILL BE FAR
ENOUGH REMOVED FROM THE STORM/SQUALL LINE DEVELOPMENT FARTHER EAST
AND WILL TRACK TOWARD THE ARROWHEAD OF MN...AND PERHAPS INTO PARTS
OF NRN WI THROUGH LATE TODAY.

...NORTHEAST...
A WEAK UPPER WAVE OBSERVED ON WV IMAGERY OVER W CNTRL NY APPEARS TO
HAVE EMANATED FROM ACROSS MN 24 HRS AGO. THE SUBTLE WAVE HAS
PROVIDED SUFFICIENT FORCING FOR ASCENT TO MAINTAIN A LOOSELY
ORGANIZED COMPLEX OF STORMS...NOW WEAKENING WHILE MOVING SEWD ACROSS
CNTRL NY. DOWNSTREAM DESTABILIZATION AND LESSENING INHIBITION ALONG
A DIFFUSE QUASI-STATIONARY BOUNDARY FROM NERN PA TO SRN NEW ENGLAND
MAY RESULT IN AN INCREASE IN TSTMS IN THESE AREAS LATER THIS
AFTERNOON. THIS REGION LIES WITHIN BROAD RIDGE AXIS WITH ABOUT
15-20KT OF MID FLOW...SOUTH OF STRONGER MID LEVEL FLOW ACROSS PARTS
OF NY AND NRN NEW ENGLAND. WITH HIGH TEMPS FORECAST IN THE UPPER 80S
TO LOWER 90S F AND DEWPOINT TEMPS WELL INTO THE 60S F...MODERATE
SURFACE-BASED INSTABILITY WILL DEVELOP. SOME MODEL FORECASTS SUGGEST
AN INCREASE IN SURFACE-BASED CONVECTION IN THE 17-18Z PERIOD BUT
OTHER SCENARIOS DEPICT LESS DEVELOPMENT. ANY STORMS THAT CAN
INITIATE WILL POSE SOME THREAT OF WIND DAMAGE AND HAIL GIVEN
MAGNITUDE OF ANTICIPATED DESTABILIZATION IN THE WARM SECTOR BUT
OVERALL STORM ORGANIZATION MAY REMAIN LIMITED BY LACK OF STRONGER
FLOW/SHEAR.

FARTHER NORTHEAST...A WEAK BACK DOOR FRONT HAS SPREAD SWD ACROSS NRN
NEW ENGLAND. DRIER AIR AND CLOUD COVER WILL GREATLY INHIBIT
SURFACE-BASED DESTABILIZATION ACROSS THESE AREAS. HOWEVER...THE
FRONT WILL ACT TO REINFORCE THE GRADIENT BETWEEN THE VERY WARM AND
UNSTABLE CONDITIONS DEVELOPING ACROSS NY AND POINTS SOUTH...AND MAY
ALSO AID DEEP-LAYER ASCENT ACROSS NEW ENGLAND LATER TODAY INTO
TONIGHT. FORCING FOR LIFT ACROSS THIS BOUNDARY IS UNCERTAIN.
HOWEVER...LARGE SCALE PATTERN SUGGESTS THAT WEAK AND ILL-DEFINED
IMPULSES...ORIGINATING IN DEEP CONVECTION UPSTREAM...MAY ENHANCE
LIFT ALONG THIS NW-SE ORIENTED FRONTAL ZONE TO SUPPORT AN INCREASE
IN NOCTURNAL STORMS WITH HAIL AND HEAVY RAIN POTENTIAL.

...SRN PLAINS...
A LARGE WARM SECTOR IS CURRENTLY IN PLACE ACROSS WRN/CNTRL TX WHERE
SFC DEWPOINTS ARE IN THE MID TO UPPER 60S F. A COLD FRONT IS LOCATED
FROM WRN OK EXTENDING SWWD ACROSS WEST TX. ALONG AND TO THE
SOUTHEAST OF THE FRONT...MODERATE INSTABILITY IS ALREADY PRESENT. AS
SFC TEMPS WARM INTO EARLY TO MID-AFTERNOON...MLCAPE VALUES SHOULD
PEAK IN THE 2500 TO 3500 J/KG RANGE FROM JUST EAST OF THE MIDLAND
AREA NEWD TO AROUND WICHITA FALLS. MODEL FORECASTS ARE IN FAIRLY
GOOD AGREEMENT...DEVELOPING THUNDERSTORMS ON THE WRN EDGE OF
INSTABILITY ON THE CAP ROCK NEAR LUBBOCK LATE THIS AFTERNOON. THIS
CONVECTION SHOULD SPREAD NEWD ACROSS NW TX INTO SW OK BY EARLY TO
MID EVENING.

FORECAST SOUNDINGS ALONG THE AXIS OF MODERATE TO STRONG
INSTABILITY LATE THIS AFTERNOON SHOW 0-6 KM SHEAR OF 40 TO 50 KT
WITH STEEP MID-LEVEL LAPSE RATES OF AT 8.0 TO 8.5 C/KM. THIS SHOULD
BE FAVORABLE FOR SUPERCELLS WITH LARGE HAIL AND THE MORE DOMINANT
SUPERCELLS MAY HAVE HAIL GREATER THAN 2 INCHES IN DIAMETER.
THUS....A 30 PERCENT PROBABILITY OF HAIL...SOME SIGNIFICANT IN
EXCESS OF 2 INCHES....WILL BE MAINTAINED IN THIS OTLK ACROSS NW TX.
ALTHOUGH A TORNADO THREAT MAY DEVELOP AS THE LOW-LEVEL JET INCREASES
ACROSS NW TX EARLY THIS EVENING...THE TORNADO THREAT APPEARS
CONDITIONAL. FORECAST SOUNDINGS AT WICHITA FALLS AT 02Z SHOW 15 TO
20 KT OF 0-1 KM SHEAR AND DROP LCL HEIGHTS TO AROUND 1100 METERS
SUGGESTING THE ENVIRONMENT COULD BECOME SUPPORTIVE OF AN ISOLATED
TORNADO THREAT WITH THE MOST INTENSE STORMS. AT THIS POINT...WILL
NOT ADD A 5 PERCENT TORNADO PROBABILITY DUE TO THE CONDITIONAL
NATURE OF THE THREAT. A WIND DAMAGE THREAT SHOULD ALSO ACCOMPANY
SUPERCELLS WITH THE SEVERE THREAT DEVELOPING NEWD INTO SW OK THIS
EVENING. OTHER STORMS MAY DEVELOP FURTHER TO THE NORTHEAST ACROSS
CNTRL AND NERN OK INTO SW MO BUT WEAKER DEEP LAYER SHEAR AND WARM
AIR ALOFT WITH NEWD EXTENT SHOULD LIMIT A MORE
SUBSTANTIAL/WIDESPREAD SEVERE THREAT.

...SRN GA/NERN FL...
WILL INCLUDE A VERY LOW TORNADO PROBABILITY WITH THIS OTLK ACROSS
NRN/NERN QUADRANT OF TD BERYL. VERY MOIST/SATURATED TROPICAL
AIRMASS EXISTS WITHIN THE WEAKENING CIRCULATION ACROSS NRN FL AND
SRN GA. WHILE LATEST INDICATIONS ALSO SUGGEST WIDESPREAD CLOUD COVER
AND LITTLE IN THE WAY OF SURFACE-BASED INSTABILITY...WIND FIELDS
AROUND THE CYCLONE REMAIN STRONG AND 0-1 KM SHEAR VALUES ARE
ESTIMATED TO BE AROUND 20 TO 30 KT. THIS ENVIRONMENT COULD SUPPORT
LOW-TOPPED ROTATING STORMS IF GREATER DESTABILIZATION CAN BE
REALIZED. IT IS POSSIBLE THAT BREAKS IN THE CLOUD COVER WITHIN THE
NERN SEMI-CIRCLE OF THE CIRCULATION COULD RESULT IN POCKETS OF
INSTABILITY AND ALLOW FOR A FEW DISCRETE UPDRAFTS TO PERSIST THIS
AFTERNOON. ANY STORMS EXHIBITING PERSISTENT ROTATION IN THE PRESENCE
OF SURFACE-BASED INSTABILITY WOULD POSE SOME THREAT OF A WEAK/BRIEF
TORNADO. HOWEVER...THIS REMAINS A LOW PROBABILITY EVENT.

..CARBIN/HURLBUT/BROYLES.. 05/28/2012

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