SWODY2
SPC AC 201726
DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1226 PM CDT TUE MAY 20 2008
VALID 211200Z - 221200Z
...THERE IS A SLGT RISK OF SVR TSTMS ACROSS PARTS OF ERN WY...FAR
WRN NEB AND NE CO...
...HIGH PLAINS...
AN UPPER-LEVEL TROUGH OVER THE WEST COAST WILL MOVE INTO THE
INTERMOUNTAIN WEST AND BECOME HIGHLY MERIDIONAL TONIGHT. IN
RESPONSE...A 30 TO 45 KT LOW-LEVEL JET IS FORECAST TO DEVELOP ACROSS
THE HIGH PLAINS. THIS WILL HELP LOW-LEVEL MOISTURE TO INCREASE
ACROSS THE HIGH PLAINS WITH UPPER 40S AND LOWER 50S F SFC DEWPOINTS
LIKELY FROM WRN NEB EXTENDING WWD ACROSS NE CO AND ERN WY BY
WEDNESDAY AFTERNOON. ALSO...IN RESPONSE TO THE UPPER-LEVEL
SYSTEM...A SFC LOW IS FORECAST TO DEEPEN ACROSS SERN WY AND ERN CO
ON WEDNESDAY. SFC HEATING AND INCREASING LOW-LEVEL CONVERGENCE NEAR
THE LOW AND ALONG A FRONTAL BOUNDARY SHOULD RESULT IN SCATTERED
THUNDERSTORM DEVELOPMENT ESPECIALLY ACROSS ERN WY WHERE CAPPING
SHOULD NOT BE PROBLEMATIC. THE AMOUNT OF LOW-LEVEL MOISTURE IN PLACE
BY WEDNESDAY AFTERNOON ALONG WITH SFC HEATING SHOULD ALLOW POCKETS
OF MODERATE INSTABILITY TO FORM AND THIS WILL HELP SUSTAIN STRONG
CONVECTIVE DEVELOPMENT THROUGH THE LATE AFTERNOON AND EARLY EVENING.
FURTHER SOUTH ACROSS ERN CO...CONVECTIVE DEVELOPMENT SHOULD REMAIN
ISOLATED DUE TO A CAPPING INVERSION.
CONCERNING THE SEVERE POTENTIAL...VERTICAL SHEAR PROFILES WILL
GRADUALLY BECOME MORE FAVORABLE FOR ORGANIZED STORMS DURING THE DAY
ACROSS THE SLIGHT RISK AREA AS MID-LEVEL FLOW INCREASES AHEAD OF THE
DEEPENING UPPER-LEVEL TROUGH. FORECAST SOUNDINGS NEAR AND NORTH OF
CHEYENNE WY WEDNESDAY AFTERNOON AND EVENING INCREASE 0-6 KM SHEAR
FROM ABOUT 25 KTS AT 18Z TO ABOUT 50 KTS AT 03Z. IN
ADDITION...MID-LEVEL LAPSE RATES WILL BE QUITE STEEP AND COMBINED
WITH THE AMOUNT OF SHEAR AND INSTABILITY SHOULD BE SUPPORTIVE OF
SUPERCELLS CAPABLE OF PRODUCING LARGE HAIL. A FEW DAMAGING WIND
GUSTS WILL ALSO BE POSSIBLE.
...SERN TX PANHANDLE/NW TX...
A DRYLINE IS FORECAST TO BE IN PLACE ACROSS NW TX AND THE ERN TX
PANHANDLE WEDNESDAY AFTERNOON. SFC DEWPOINTS SHOULD BE IN THE LOWER
60S F EAST OF THE DRYLINE AND MODERATE TO STRONG INSTABILITY IS
FORECAST TO DEVELOP. ALTHOUGH LARGE-SCALE ASCENT WILL REMAIN WEAK
ALONG THE DRYLINE...ENOUGH LOW-LEVEL CONVERGENCE MAY EXIST FOR
ISOLATED THUNDERSTORM DEVELOPMENT. THE AMOUNT OF VERTICAL
SHEAR...INSTABILITY COMBINED WITH VERY STEEP MID-LEVEL LAPSE RATES
EVIDENT ON FORECAST SOUNDINGS WILL BE SUFFICIENT FOR SUPERCELL
DEVELOPMENT WITH LARGE HAIL IF A STORM CAN INITIATE AND PERSIST LATE
WEDNESDAY AFTERNOON.
...SRN GA/NRN FL...
A BROAD UPPER-LEVEL TROUGH WILL REMAIN IN PLACE ACROSS THE CNTRL AND
SRN APPALACHIAN MTNS WITH A QUASI-STATIONARY FRONTAL BOUNDARY
LOCATED FROM SRN MS EXTENDING EWD INTO SRN AL AND SRN GA. MODERATE
INSTABILITY IS FORECAST TO DEVELOP ALONG AND SOUTH OF THE BOUNDARY
WHERE SFC DEWPOINTS SHOULD BE IN THE LOWER TO MID 60S F. SFC HEATING
AND LOW-LEVEL CONVERGENCE WILL ALLOW SCATTERED THUNDERSTORMS TO
INITIATE ALONG THE BOUNDARY BY EARLY AFTERNOON. FORECAST SOUNDINGS
ACROSS FAR SRN GA AND NRN FL WEDNESDAY AFTERNOON SHOW UNIDIRECTIONAL
WLY FLOW WHICH COMBINED WITH STEEP LOW-LEVEL LAPSE RATES AND THE
AMOUNT OF INSTABILITY MAY RESULT IN A POTENTIAL FOR DAMAGING WIND
GUSTS ESPECIALLY ACROSS SRN GA AND THE FL PANHANDLE WHERE VERTICAL
SHEAR SHOULD BE THE STRONGEST. A FEW MARGINALLY SEVERE DAMAGING WIND
GUSTS ASSOCIATED WITH PULSE THUNDERSTORMS WILL ALSO BE POSSIBLE
FARTHER WEST ACROSS SRN AL AND SRN MS WHERE INSTABILITY IS FORECAST
TO BE SLIGHTLY STRONGER.
..BROYLES.. 05/20/2008
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