SWODY1
SPC AC 291957
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0257 PM CDT FRI JUN 29 2007
VALID 292000Z - 301200Z
..THERE IS A SLGT RISK OF SVR TSTMS ACROSS PARTS OF THE ERN
SEABOARD...
..THERE IS A SLGT RISK OF SVR TSTMS ACROSS PARTS OF MONTANA...
..SE VA/NC/SC/ERN GA...
A BROAD ZONE OF WLY FLOW IS LOCATED ACROSS THE ERN SEABOARD
ASSOCIATED WITH THE SRN PART OF A BROAD UPPER-LEVEL TROUGH OVER THE
NERN STATES. AT THE SFC...A WEAKLY DEFINED COLD FRONT IS LOCATED
ACROSS VA WITH A SFC LOW OVER ERN NC. SCATTERED TO NUMEROUS
THUNDERSTORMS ARE DEVELOPING THIS AFTERNOON ALONG CONVERGENCE ZONES
AND IN AREAS OF STRONGER INSTABILITY. WSR-88D VWPS ACROSS THE REGION
SHOW UNIDIRECTIONAL SHEAR PROFILES WITH ENOUGH VERTICAL SHEAR FOR
MULTICELL SEVERE STORMS. THE GREATEST THREAT FOR SEVERE SHOULD EXIST
ALONG AN AXIS OF MODERATE INSTABILITY WHICH IS ANALYZED FROM ERN NC
SWWD ACROSS SC INTO CNTRL GA. OBJECTIVE ANALYSIS ALSO SHOWS 0-3 KM
LAPSE RATES EXCEEDING 8.0 C/KM ACROSS MUCH OF THIS CORRIDOR AND THIS
ALONG WITH DEWPOINTS IN THE LOWER 70S F SHOULD FAVOR WIND DAMAGE AS
THE MAIN THREAT. A MORE MARGINAL THREAT MAY ALSO EXIST WWD ACROSS TN
WHERE LOW-LEVEL LAPSE RATES ARE ALSO LOCALLY STEEP.
..MONTANA...
AN UPPER-LEVEL TROUGH OFF THE PACIFIC NORTHWEST COAST WILL MOVE
ONSHORE LATE THIS AFTERNOON WITH GRADUAL HEIGHT FALLS ACROSS THE NRN
ROCKIES. LARGE-SCALE ASCENT WILL INCREASE ACROSS THE REGION AS A
SUBTLE SHORTWAVE TROUGH EVIDENT ON WATER VAPOR IMAGERY MOVES NEWD
LATE THIS AFTERNOON. THIS SHOULD SUPPORT SCATTERED THUNDERSTORM
DEVELOPMENT ACROSS MUCH OF WRN...NRN AND CNTRL MT WITH MCS
DEVELOPMENT POSSIBLE BY EARLY EVENING.
A 70 KT MID-LEVEL JET CURRENTLY CENTERED OVER ORE WILL CONTINUE TO
APPROACH THE REGION THIS AFTERNOON. THIS IS CREATING MODERATE TO
STRONG VERTICAL SHEAR PROFILES ACROSS WRN MT WHICH SHOULD BE
SUFFICIENT FOR SUPERCELLS. FURTHER EAST...VERTICAL SHEAR IS NOT AS
STRONG BUT THE SHEAR SHOULD INCREASE AS THE MID-LEVEL JET APPROACHES
THROUGH EARLY EVENING. OBJECTIVE ANALYSIS ALREADY SHOWS MLCAPE
VALUES ABOVE 2000 J/KG ACROSS MUCH OF NRN MT WITH STEEP MID-LEVEL
LAPSE RATES. AS A RESULT...THE ENVIRONMENT APPEARS FAVORABLE FOR
LARGE HAIL WITH ANY SUPERCELLS THAT DEVELOP. PERSISTENT SUPERCELLS
MAY HAVE AN EXTENDED POTENTIAL TO PRODUCE LARGE HAIL WITH VERY LARGE
HAIL ALSO POSSIBLE. CONSIDERING THE AMOUNT OF INSTABILITY IN
PLACE...A HIGHER CONCENTRATION OF SEVERE STORMS MAY OCCUR IF AN MCS
CAN ORGANIZE AND MOVE NEWD ACROSS WRN AND NRN MT EARLY THIS EVENING.
..NM/CO...
LATEST WATER VAPOR IMAGERY SHOWS AN UPPER-LEVEL RIDGE CURRENTLY
LOCATED ACROSS THE SRN AND CNTRL ROCKIES. THUNDERSTORMS ARE
DEVELOPING IN THE HIGHER TERRAIN OF SRN CO AND NM ON THE ERN SIDE OF
THE UPPER-LEVEL RIDGE. ALTHOUGH FLOW IS RELATIVELY WEAK ALOFT...A
MARGINAL SEVERE THREAT MAY EXIST WITH STORMS THAT MOVE OFF THE
HIGHER TERRAIN ALONG AN AXIS OF MODERATE INSTABILITY FROM NEAR
DENVER CO EXTENDING SWD TO PUEBLO CO TO NEAR ALAMOGORDO NM. THIS
ACTIVITY SHOULD REMAIN CLOSELY TIED TO SFC HEATING WITH ANY SEVERE
THREAT CONCENTRATED IN A BRIEF WINDOW LATE THIS AFTERNOON.
.BROYLES.. 06/29/2007
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