SWODY1
SPC AC 180540
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1240 AM CDT MON APR 18 2011
VALID 181200Z - 191200Z
...NO SVR TSTM AREAS FORECAST...
...SYNOPSIS...
ZONAL FLOW FIELD ALOFT -- IN PLACE AT THE START OF THE PERIOD --
WILL BEGIN GRADUAL AMPLIFICATION...AS A TROUGH BEGINS EXPANDING
ACROSS THE WRN U.S. IN CONJUNCTION WITH DOWNSTREAM RIDGING.
AT THE SURFACE...LEE CYCLONE OVER OK EARLY IS PROGGED TO WEAKEN --
BUT BE REPLACED LATER IN THE PERIOD BY A STRENGTHENING LOW SHIFTING
SEWD OUT OF CO IN RESPONSE TO THE WRN UPPER TROUGHING. EXTENDING
EWD INTO THE OH VALLEY REGION...A SHARPENING WARM FRONT SHOULD ACT
AS A LIFTING MECHANISM FOR CONVECTIVE DEVELOPMENT -- MAINLY DURING
THE SECOND HALF OF THE PERIOD.
...NERN KS EWD ACROSS THE MID MS VALLEY TO SWRN OH/N CENTRAL KY...
WHILE PERSISTENT SLY LOW-LEVEL FLOW ADVECTS HIGHER THETA-E AIR NWD
INTO SRN MO AND THE LOWER OH VALLEY REGION...WLYS ALOFT WILL
CONTINUE TO ADVECT AN EML EWD...RESULTING IN A CAPPED WARM SECTOR.
THIS COMBINED WITH WEAK HEIGHT RISES/RIDGING ALOFT AHEAD OF THE WRN
TROUGH SHOULD YIELD A WARM SECTOR GENERALLY DEVOID OF CONVECTION
THROUGH THE PERIOD.
ISENTROPIC LIFT ATOP THE SHARPENING BAROCLINIC ZONE HOWEVER --
PARTICULARLY AS A LOW-LEVEL JET INTENSIFIES THROUGH THE EVENING --
SHOULD SUPPORT MAINLY ELEVATED CONVECTIVE DEVELOPMENT...INITIALLY
FROM MO EWD AND THEN POSSIBLY WWD LATER IN THE EVENING ACROSS NRN
KS. WITH ELEVATED INSTABILITY IN EXCESS OF 1000 J/KG AND MID-LEVEL
WLYS GENERALLY NEAR 40 KT...POTENTIAL FOR A FEW STRONGER STORMS
CAPABLE OF PRODUCING MARGINAL HAIL APPEARS TO EXIST. WILL ALSO
INCLUDE LOW PROBABILITY FOR SURFACE-BASED SEVERE THREAT IN THE
EXPECTED LOCATION OF THE SURFACE FRONT...TO ACCOUNT FOR ANY ISOLATED
DEVELOPMENT OF STORMS MORE CLOSELY ROOTED TO THE BOUNDARY LAYER.
..GOSS/COHEN.. 04/18/2011
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