Thursday, July 24, 2008

DAY1SVR: Day 1 Convective Outlook

ACUS01 KWNS 250052
SWODY1
SPC AC 250048

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0748 PM CDT THU JUL 24 2008

VALID 250100Z - 251200Z

...THERE IS A SLGT RISK OF SVR TSTMS OVER A PORTION OF THE MIDDLE
AND LOWER MO RIVER VALLEY...

...THERE IS A SLGT RISK OF SVR TSTMS OVER A PORTION OF ME...

...CNTRL AND NRN PLAINS AREA...

EARLY THIS EVENING SURFACE BOUNDARY/FRONT EXTENDS FROM NWRN MN SWWD
THROUGH NWRN SD INTO E CNTRL WY. A WEAK E-W ORIENTED SURFACE
BOUNDARY WAS INDICATED ACROSS CNTRL NEB. FARTHER SOUTH A
QUASISTATIONARY FRONT EXTENDS FROM A WEAK SURFACE LOW IN SERN NEB
SEWD THROUGH NE KS...NW AND S CNTRL MO. A WEAK TROUGH EXTENDS SWWD
FROM THE LOW THROUGH WRN KS AND SERN CO. WV IMAGERY INDICATES A
SHORTWAVE TROUGH MOVING EWD THROUGH POST FRONTAL ZONE ACROSS ERN MT
AND WRN ND.

STRONG INSTABILITY PERSISTS WHERE STEEP MID-LEVEL LAPSE RATES
OVERLAP MOIST AXIS IN CORRIDOR FROM NW MO...NE KS...CNTRL AND ERN
NEB AND ERN SD WITH MLCAPE FROM 2000 TO 3000 J/KG. THE PREVIOUSLY
MENTIONED BOUNDARIES AND FORCING OVER THE HIGHER TERRAIN HAVE
PROVIDED FOCUSING MECHANISMS FOR STORMS TO DEVELOP FROM ERN WY
THROUGH WRN SD...NEB AND NERN KS. INSTABILITY AXIS REMAINS ON SRN
FRINGE OF STRONGER MID LEVEL FLOW ASSOCIATED WITH EWD MIGRATING
SHORTWAVE TROUGH. ESELY LOW LEVEL FLOW BENEATH 25 TO 35 KT MID LEVEL
WINDS HAVE CONTRIBUTED TO SUFFICIENT BULK SHEAR FOR A FEW STORMS TO
EVOLVE INTO SUPERCELLS.

ISOLATED STORM CURRENTLY MOVING SWD THROUGH NERN KS APPEARS TO HAVE
BECOME OUTFLOW DOMINANT...AND THE 00Z TOP SOUNDING INDICATES FAIRLY
HIGH LCL HEIGHTS. HOWEVER...A WINDOW OF OPPORTUNITY MAY REMAIN FOR
AN ISOLATED TORNADO OR TWO PARTICULARLY IN VICINITY OF
STATIONARY/WARM FRONT FROM SERN NEB...NE KS AND NW MO AS THE LOW
LEVEL JET STRENGTHENS AND LCLS DECREASE PRIOR TO THE BOUNDARY LAYER
DECOUPLING. OTHERWISE...ISOLATED LARGE HAIL AND DAMAGING WIND WILL
BE THE PRIMARY THREATS. POTENTIAL WILL EXIST FOR STORMS TO EVOLVE
INTO ONE OR MORE MCSS THIS EVENING....ONE BEING ACROSS SE NEB..NE
KS...SRN IA INTO NRN MO WHERE THE STRENGTHENING LOW LEVEL JET WILL
ENHANCE ISENTROPIC LIFT IN VICINITY OF THE STATIONARY FRONT. OTHER
STORMS SPREADING SEWD OFF THE HIGHER TERRAIN THROUGH WRN SD AND WRN
NEB MIGHT ALSO CONGEAL INTO AN MCS OVERNIGHT. THE GREATEST SEVERE
THREAT EXIST THIS EVENING WITH A MORE LIMITED THREAT OVERNIGHT.

...NEW ENGLAND...

A COLD FRONT EXTENDS ACROSS EXTREME ERN NY SWD TO ALONG THE ATLANTIC
SEABOARD. RICH LOW LEVEL MOISTURE WITH DEWPOINTS NEAR 70 HAVE SPREAD
THROUGH THE PRE-FRONTAL WARM SECTOR. BAND OF WEAK CONVECTION
CONTINUES ALONG THE WARM CONVEYOR BELT...AND THIS ACTIVITY WILL
LIKELY PERSIST OVERNIGHT AND SHIFT EWD THROUGH ME. OTHER STORMS ARE
DEVELOPING OVER ERN NY ALONG COLD FRONT AND WITHIN ZONE OF DPVA
ASSOCIATED WITH NEWD EJECTING VORT MAX. STORMS DEVELOPING ALONG THE
FRONT MAY POSE A MARGINAL RISK OF ISOLATED STRONG WIND GUSTS THROUGH
MID EVENING. FARTHER EAST OVER ME...0-1 KM HODOGRAPHS AND DEEP WIND
PROFILES WILL REMAIN STRONG AND SUPPORTIVE OF A THREAT OF LOW TOPPED
SUPERCELLS...BOWING STRUCTURES AND PERHAPS A BRIEF TORNADO.
HOWEVER...THE MARGINAL THERMODYNAMIC ENVIRONMENT WITH MODEST
INSTABILITY AND LAPSE RATES WILL LIKELY POSE AN OVERALL LIMITING
FACTOR AND SUGGEST THREAT WILL REMAIN CONDITIONAL IN THIS REGION
OVERNIGHT.

...S TX...

LOW LEVEL HODOGRAPHS WILL REMAIN SUFFICIENT FOR A LOW TOPPED
SUPERCELL OR TWO OVER PARTS OF S TX NORTH OF THE CENTER OF DOLLY
WHICH CONTINUES WWD THROUGH NRN MEXICO. HOWEVER...LOSS OF DIABATIC
HEATING SUGGEST THE THERMODYNAMIC ENVIRONMENT WILL BECOME
INCREASINGLY MARGINAL. OVERALL THREAT APPEARS TOO LOW TO CONTINUE A
CATEGORICAL RISK IN THIS REGION OVERNIGHT.

..DIAL.. 07/25/2008

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