DAY1SVR: Day 1 Convective Outlook

ACUS01 KWNS 011632
SWODY1
SPC AC 011630

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1130 AM CDT FRI JUN 01 2012

VALID 011630Z - 021200Z

...THERE IS A MDT RISK OF SVR TSTMS ACROSS PARTS OF SRN PA...FAR ERN
WV...MD AND NRN VA...

...THERE IS A SLGT RISK OF SVR TSTMS ACROSS PARTS OF THE UPPER OH
VALLEY...MID-ATLANTIC...CAROLINAS AND ERN GULF COAST STATES...

...THERE IS A SLGT RISK OF SVR TSTMS ACROSS THE TX PANHANDLE AND
NORTHWEST TX...

...MID-ATLANTIC/UPPER OH VALLEY/CAROLINAS...
THE LATEST WATER VAPOR IMAGERY SHOWS AN UPPER-LEVEL TROUGH EXTENDING
SWD ACROSS THE OH AND TN VALLEYS. THIS FEATURE WILL BECOME
NEGATIVELY TILTED TODAY MOVING EWD INTO THE CNTRL APPALACHIAN MTNS.
A BAND OF WELL-FOCUSED LARGE-SCALE ASCENT IS LOCATED TO THE EAST OF
THE TROUGH WHICH IS PROVIDING SUPPORT FOR A LINE OF THUNDERSTORMS
EXTENDING SWD FROM ERN OH INTO FAR ERN KY. THIS LINE WILL MOVE EWD
INTO A WEAKLY UNSTABLE AIRMASS BUT WILL ALSO GAIN ACCESS TO
INCREASING LOW-LEVEL MOISTURE AND SLIGHTLY STRONGER INSTABILITY THIS
AFTERNOON. FOR THIS REASON...THE LINE IS EXPECTED TO SLOWLY RAMP UP
IN INTENSITY WITH A WIND DAMAGE THREAT GRADUALLY DEVELOPING.

FURTHER TO THE EAST ACROSS ERN NC...ERN VA AND MD...MESOANALYSIS
CURRENTLY SHOWS A CORRIDOR OF MODERATE INSTABILITY WHERE MLCAPE IS
ESTIMATED IN THE 1500 TO 2500 J/KG RANGE AND SFC DEWPOINTS ARE
APPROACHING 70 F. THUNDERSTORMS ARE EXPECTED TO INITIATE ALONG THE
INSTABILITY AXIS THIS AFTERNOON WITH STORMS SPREADING NEWD ACROSS
THE MID-ATLANTIC LATE THIS AFTERNOON INTO EARLY THIS EVENING.
FORECAST SOUNDINGS ACROSS THE WARM SECTOR LATE THIS AFTERNOON SHOW
0-6 KM SHEAR VALUES IN THE 35 TO 40 KT RANGE WITH 0-3 KM STORM
RELATIVE HELICITIES AROUND 250 M2/S2 SUGGESTING THE ENVIRONMENT WILL
SUPPORT ROTATING STORMS AND TORNADOES. A TORNADO THREAT WILL LIKELY
DEVELOP AS THE STORMS INTERACT WITH A WARM FRONT WHICH IS FORECAST
TO BE FROM SCNTRL PA EXTENDING SSEWD ACROSS NRN VA AND MD AS THE
LINE APPROACHES FROM THE WEST. THE TORNADO THREAT SHOULD INCREASE
ACROSS PA AND MD AS THE STRONGEST BAND OF LARGE-SCALE ASCENT
APPROACHES LATER THIS AFTERNOON. A COUPLING OF THE LOW AND MID-LEVEL
JETS IS ALSO FORECAST TO OCCUR ACROSS NRN VA...MD AND PA WHICH MAY
ALSO HELP TO ENHANCE THE QLCS TORNADO THREAT. HAVE ADDED A MODERATE
RISK IN THE WASHINGTON DC METRO...BALTIMORE AREAS WHERE THE TORNADO
THREAT IS EXPECTED TO BE THE GREATEST AND WHERE AN ISOLATED STRONG
TORNADO CAN NOT BE RULED OUT. ANY ROTATING STORMS SHOULD ALSO BE
CAPABLE OF PRODUCING WIND DAMAGE. AS THE STRONGER LARGE-SCALE ASCENT
MOVES ACROSS THE MID-ATLANTIC EARLY THIS EVENING...A WELL-ORGANIZED
LINEAR MCS IS EXPECTED TO BECOME THE DOMINANT CONVECTIVE FEATURE
WITH AN ENHANCED WIND DAMAGE THREAT PRESENT ACROSS A LARGE AREA OF
THE MID-ATLANTIC.

FURTHER SOUTH ACROSS THE CAROLINAS...LARGE-SCALE ASCENT WILL BE
WEAKER THAN IN AREAS TO THE NORTH. HOWEVER...MESOANALYSIS ALREADY
SHOWS MODERATE INSTABILITY IN PLACE AND MODEL FORECASTS DO DEVELOP A
LINE OF THUNDERSTORMS ALONG THE INSTABILITY AXIS THIS AFTERNOON.
FORECAST SOUNDINGS LATE THIS AFTERNOON IN THE ERN CAROLINAS SHOW 0-6
KM SHEAR OF 30 TO 35 KT SUGGESTING THE ENVIRONMENT WILL SUPPORT
SEVERE STORMS. AS LOW-LEVEL LAPSE RATES BECOME STEEP THIS
AFTERNOON...WIND DAMAGE WILL BE POSSIBLE WITH A LINE OF STORMS
FORMING JUST AHEAD OF A COLD FRONT APPROACHING THE REGION FROM THE
NORTHWEST.

...SRN GA/NRN FL...
REMNANT MCV FROM OVERNIGHT CONVECTION IS SHEARING NEWD AT ROUGHLY
25KT ACROSS SERN AL INTO SWRN GA. IT APPEARS DIURNAL HEATING IS NOW
CONTRIBUTING GREATLY TO THE RECENT INCREASE IN TSTM ACTIVITY ALONG
LEADING EDGE OF DEBRIS CANOPY AND CONVECTIVE OUTFLOW. GIVEN THE
MODEST DEEP LAYER SHEAR AND THE EXPECTED GRADUAL INCREASE IN
CONVECTION AHEAD OF THIS FEATURE A SLIGHT RISK WILL BE ADDED TO THIS
REGION TO ACCOUNT FOR ISOLATED DAMAGING WINDS AND PERHAPS SOME HAIL.
CURRENT SPEED OF THIS FEATURE SUGGESTS THE BACK EDGE OF FORCING WITH
MCV WILL PROGRESS INTO SERN GA BY 21Z.

...SWRN KS/TX AND OK PANHANDLES...
NORTHWEST FLOW WILL BE IN PLACE ACROSS THE SRN PLAINS TODAY WITH
SEVERAL SUBTLE IMPULSES MOVING SEWD ACROSS THE REGION. MESOANALYSIS
ALREADY SHOWS AN AXIS OF MODERATE INSTABILITY IN PLACE ACROSS ERN
NM. AS THE INSTABILITY AXIS SHIFTS EWD INTO WEST TX THIS
AFTERNOON...STRONG INSTABILITY SHOULD DEVELOP AS THE CAPPING
INVERSION WEAKENS. THIS SHOULD ALLOW FOR SCATTERED THUNDERSTORM
DEVELOPMENT ACROSS THE TX PANHANDLE WITH THIS CONVECTION GRADUALLY
MOVING SEWD INTO NORTHWEST TX EARLY THIS EVENING. FORECAST SOUNDINGS
AT AMARILLO AT 02/00Z SHOW 0-6 KM SHEAR IN THE 40 TO 50 KT RANGE
WITH MID-LEVEL LAPSE RATES APPROACHING 8.0 C/KM. THIS SHOULD SUPPORT
A SUPERCELL AND LARGE HAIL THREAT. HOWEVER...LARGE TEMP-DEWPOINT
SPREADS MAY ALSO HELP ENHANCE DOWNDRAFT SPEEDS SUGGESTING A WIND
DAMAGE THREAT WILL ALSO EXIST ESPECIALLY IF THE STORMS CAN CONGEAL
INTO A LINE EARLY THIS EVENING.

..BROYLES/CARBIN/COHEN/DARROW.. 06/01/2012

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