DAY1SVR: Day 1 Convective Outlook

ACUS01 KWNS 101946
SWODY1
SPC AC 101944

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0244 PM CDT TUE JUL 10 2012

VALID 102000Z - 111200Z

...THERE IS A SLGT RISK OF SVR TSTMS ACROSS PARTS OF THE SRN
APPALACHIAN MTNS AND CAROLINAS...

A COUPLE OF CHANGES HAVE BEEN MADE TO THE OUTLOOK AT 20Z. THE FIRST
CHANGE IS TO EXTEND THE SLIGHT RISK AREA ESEWD ACROSS PARTS OF CNTRL
AND ERN SC. MESOANALISYS SUGGESTS THAT A CORRIDOR OF MODERATE TO
STRONG INSTABILITY IS LOCATED FROM ERN TN ESEWD ACROSS SC WHERE A
SEVERE THREAT SHOULD EXIST THROUGH LATE AFTERNOON MAINLY FOR WIND
DAMAGE. ALSO...LINED UP THE 5 PERCENT HAIL PROBABILITY WITH THE EDGE
OF THE SLIGHT RISK AREA TO CORRESPOND WITH THE STRONGER INSTABILITY.
THE SECOND CHANGE TO THE OUTLOOK IS TO REMOVE PARTS OF THE LOWER MS
VALLEY FROM THE 5 PERCENT WIND PROBABILITY WHERE THE AIRMASS IS
WORKED OVER AND INSTABILITY REMAINS WEAK. OTHERWISE...MINOR CHANGES
HAVE BEEN MADE TO THE THUNDER LINES.

..BROYLES.. 07/10/2012

.PREV DISCUSSION... /ISSUED 1130 AM CDT TUE JUL 10 2012/

...SRN APPALACHIANS REGION...
WATER VAPOR IMAGERY SHOWS A MID/UPPER LEVEL DRY INTRUSION SPREADING
NWD OVER GA CO-LOCATED WITH A NNE/SSW MID LEVEL THERMAL TROUGH OVER
THE AREA. THE DRY INTRUSION IS EXPECTED TO CONTINUE LIFTING NWD AND
ENHANCE THUNDERSTORM DEVELOPMENT THIS AFTERNOON AS IT INTERACTS WITH
A SURFACE BOUNDARY EXTENDING FROM NERN AL ACROSS NRN GA INTO
UPSTATE SC. THE THERMAL CONTRAST AND MESOSCALE CIRCULATION ALONG
THE BOUNDARY MAY BE ENHANCED BY DIFFERENTIAL HEATING OWING TO MORE
CLOUDS NORTH OF THE BOUNDARY. STRONG HEATING AND DESTABILIZATION IS
LIKELY TO CONTINUE /ESPECIALLY SOUTH OF THE BOUNDARY/ WITH MLCAPE
REACHING 2000-2500 J/KG IN THE PRE-CONVECTIVE ENVIRONMENT. VISIBLE
IMAGERY SHOWS INITIAL CONVECTION DEVELOPING FROM ERN TN INTO EXTREME
NERN LA/NRN GA AS A WEAK CAP IS ERODING. ALTHOUGH WINDS ALOFT ARE
RELATIVELY WEAK...MODEL GUIDANCE INDICATES A CHANNEL OF 20 KT MID
LEVEL FLOW WILL DEVELOP THIS AFTERNOON OVER THE AREA RESULTING IN
MARGINAL VERTICAL SHEAR FOR A MIX OF MULTICELL AND PULSE STORM TYPES
TO DEVELOP. STEEP LOW LEVEL LAPSE RATES AND HIGH PW CONTENT WILL
PROMOTE FORMATION OF A FEW DOWNBURSTS WITH STRONGER CELLS INTO THE
EARLY EVENING HOURS.

...ELSEWHERE FROM THE MID ATLANTIC REGION ACROSS THE LOWER MS VALLEY
INTO TX...
GENERALLY WEAK WINDS ALOFT AND MINIMAL VERTICAL SHEAR IS PRESENT
ACROSS MUCH OF THE SOUTHERN STATES...AMIDST A PERSISTENT MID/UPPER
LEVEL CYCLONIC CIRCULATION/SHEAR ZONE OVER THE LOWER MS VALLEY.
AMPLE MOISTURE WITH PW VALUES NEAR OR ABOVE 2 IN AND A WEAK CAP
INDICATE THAT THUNDERSTORMS WILL GRADUALLY INCREASE INTO THE
AFTERNOON HOURS...MODULATED BY AREAS OF MORE EXTENSIVE CLOUD COVER
WHICH WILL LOCALLY TEMPER THE MAGNITUDE OF DIABATIC HEATING.
ISOLATED WET MICROBURSTS WILL BE POSSIBLE WITH SOME STORMS THIS
AFTERNOON AND EVENING.

...NRN INTERMOUNTAIN REGION/NRN ROCKIES...
A SHORT WAVE TROUGH IS LIFTING NEWD ACROSS THE NRN INTERMOUNTAIN
REGION THIS MORNING PRECEDED BY ISOLATED THUNDERSTORMS FROM CENTRAL
ID INTO EXTREME WRN MT. THE 12Z TFX RAOB INDICATES A VERY DEEP WELL
MIXED BOUNDARY LAYER WILL DEVELOP ONCE DIABATIC HEATING REMOVES THE
SHALLOW NOCTURNAL SURFACE INVERSION. THIS ENVIRONMENT WILL SUPPORT
HIGH-BASED THUNDERSTORMS WITH POTENTIAL FOR ISOLATED STRONG/SEVERE
MICROBURSTS TO OCCUR OVER PARTS OF WRN AND CENTRAL MT AS THIS
ACTIVITY SPREADS EWD/NEWD THIS AFTERNOON. THERE IS ALSO THE
POSSIBILITY OF REDEVELOPMENT OF THUNDERSTORMS UPSTREAM FROM THE
CURRENT ACTIVITY...AS A SUBTLE VORTICITY MAX SEEN IN WATER VAPOR
IMAGERY OVER CENTRAL OREGON MOVES NEWD TOWARD CENTRAL ID AND WRN MT
LATER THIS AFTERNOON AND TONIGHT. ALTHOUGH THE INITIAL CONVECTION
MAY LOCALLY MOISTEN THE ATMOSPHERIC COLUMN...SUFFICIENT LOW/MID
LEVEL DRY AIR IS LIKELY TO PERSIST TO MAINTAIN POTENTIAL FOR
HIGH-BASED STORMS AND ASSOCIATED MICROBURSTS IN THE WAKE OF THE
CURRENT CONVECTION.

+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-
To unsubscribe from WX-STORM send e-mail to LISTSERV@LISTSERV.ILLINOIS.EDU with
"unsub wx-storm" in the body of your message. For more information write cnovy@cox.net.