Monday, May 17, 2010

DAY1SVR: Day 1 Convective Outlook

ACUS01 KWNS 171255
SWODY1
SPC AC 171254

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0754 AM CDT MON MAY 17 2010

VALID 171300Z - 181200Z

...THERE IS A SLGT RISK OF SVR TSTMS FROM THE LWR OH/TN VLYS INTO
THE SRN APPALACHIANS/CAROLINAS...

...THERE IS A SLGT RISK OF SVR TSTMS OVER THE SRN HI PLNS...

...SYNOPSIS...
SPLIT FLOW PATTERN WILL CONTINUE OVER THE LWR 48...DOWNSTREAM FROM
FULL LATITUDE...NEGATIVE TILT TROUGH NOW OFF THE W CST. MID MS VLY
UPR LOW WILL MOVE SLOWLY E AND BROADEN THROUGH TUE AS E PACIFIC
TROUGH REACHES THE SRN/WRN GRT BASIN. SFC FRONT ATTENDANT TO MS VLY
TROUGH WILL MOVE E/SE ACROSS THE LWR MS AND TN VLYS... WHILE ERN
PORTION REMAINS STNRY OVER THE SRN APPALACHIANS AND A WAVE EVOLVES
OVER THE CAROLINAS. THE WRN PART OF THE BOUNDARY WILL REDEVELOP N
ACROSS THE SRN HI PLNS LATER TODAY/TONIGHT AS PACIFIC TROUGH REACHES
THE GRT BASIN.

...LWR OH AND TN VLYS INTO SRN APPALACHIANS/CAROLINAS...
MODERATE TO STRONG SFC HEATING BENEATH COOL/DEEP CYCLONIC FLOW ON S
SIDE OF MS VLY UPR LOW WILL SUPPORT SCTD TO NUMEROUS TSTMS OVER
PARTS OF THE TN AND LWR OH VLYS LATER TODAY. OTHER STORMS MAY
CONTINUE TO FOCUS ALONG STALLED FRONT OVER THE CAROLINAS...WHERE
GREATER MOISTURE AVAILABILITY WILL OFFSET MORE LIMITED LOW LVL
HEATING. 35 KT DEEP WSWLY SHEAR SHOULD SUPPORT ORGANIZATION OF
STORMS INTO BANDS/CLUSTERS. SOME SUSTAINED ACTIVITY...INCLUDING
MULTICELLS AND MARGINAL SUPERCELLS...COULD YIELD LOCALLY DMGG WIND
AND PERHAPS MARGINALLY SVR HAIL. MOST OF THE TN/OH VLY STORMS
SHOULD WEAKEN BY EVE...BUT THOSE IN THE CAROLINAS MAY PERSIST INTO
THE NIGHT NEAR DEVELOPING SFC WAVE.

...SRN HI PLNS...
RELATIVELY MOIST SELY UPSLOPE FLOW WILL SLOWLY STRENGTHEN OVER W
TX/ERN NM TODAY/TONIGHT IN RESPONSE TO BOTH DIURNAL INFLUENCES AND
THE APPROACH OF E PACIFIC UPR TROUGH. THIS SHOULD SUPPORT
PERIODIC...DIURNALLY-ENHANCED TSTM DEVELOPMENT OVER THE SRN HI PLNS
AND ADJACENT HIGHER TERRAIN OF THE SRN RCKYS AND SW TX.

THE MID TROPOSPHERIC FLOW WILL REMAIN FAIRLY WEAK...AND LARGE SCALE
FORCING FOR ASCENT MINIMAL. BUT VEERING WIND PROFILES/ RESULTING
35+ KT DEEP WNW SHEAR...AND STEEP MID LVL LAPSE RATES ...SHOULD BE
ADEQUATE FOR SCTD SUPERCELLS/SUSTAINED MULTICELLS WITH LARGE HAIL
AND PERHAPS A BRIEF TORNADO...MAINLY LATE THIS AFTN/TONIGHT.

WHILE OVERALL SVR STORM COVERAGE/INTENSITY SHOULD LESSEN BY MID
EVE...SLOWLY INCREASING SLY LLJ MAY SUPPORT OVERNIGHT REDEVELOPMENT
OF STORMS/STORM CLUSTERS. THESE COULD POSE AN EPISODIC THREAT FOR
SVR HAIL AND DMGG WIND OVER THE SRN HI PLNS THROUGH EARLY TUE.

...INTERIOR PACIFIC NW/NRN GRT BASIN...
HEIGHT FALLS WILL CONTINUE OVER THE PACIFIC NW/NRN GRT BASIN
TODAY...WITH SEVERAL WEAK DISTURBANCES LIKELY TO CROSS THE REGION
AMIDST STRENGTHENING SLY FLOW ALOFT. PW AROUND .75 INCHES AND
MODEST AFTN DESTABILIZATION MAY YIELD A FEW STORMS WITH MARGINALLY
SVR HAIL/GUSTY WINDS.

..CORFIDI/JEWELL.. 05/17/2010

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