SWODY2
SPC AC 061709
DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1109 AM CST FRI MAR 06 2009
VALID 071200Z - 081200Z
...THERE IS A SLGT RISK OF SVR TSTMS FROM PARTS OF THE CNTRL/SRN
PLAINS INTO PORTIONS OF THE LOWER MO AND OH VALLEYS...
...SYNOPSIS...
PRIMARY FEATURE OF INTEREST DURING THE DAY TWO PERIOD WILL BE
MIDLEVEL TROUGH WHICH WILL TRANSLATE NEWD FROM THE VICINITY OF THE
FOUR CORNERS REGION INTO THE CNTRL PLAINS. AN 80-100 KT MIDLEVEL
JET STREAK WILL ACCOMPANY THIS SYSTEM NEWD WITH THE MOST SIGNIFICANT
HEIGHT FALLS/DYNAMIC FORCING FOR ASCENT SHIFTING FROM THE SRN
ROCKIES INTO THE CNTRL PLAINS.
IN THE LOW LEVELS...LEE SURFACE CYCLONE ATTENDANT TO THIS SYSTEM
WILL DEEPEN SATURDAY OVER WRN KS BEFORE DEVELOPING NEWD INTO NRN MO
SATURDAY NIGHT. THIS LOW WILL DEVELOP ALONG A BAROCLINIC ZONE WHICH
WILL REMAIN LARGELY QUASI-STATIONARY THROUGH CNTRL KS...NRN MO INTO
THE OH VALLEY. A DRYLINE EXTENDING FROM THE LOW OVER SWRN KS INTO
WRN TX WILL EVENTUALLY BE OVERTAKEN SATURDAY NIGHT BY A PACIFIC
FRONT PUSHING EWD FROM THE CNTRL AND SRN HIGH PLAINS.
...CNTRL/SRN PLAINS INTO THE LOWER MO AND OH VALLEYS...
CLUSTERS OF ELEVATED TSTMS /SOME SEVERE/ ARE EXPECTED TO BE ONGOING
SATURDAY MORNING NEAR OR N OF QUASI-STATIONARY BOUNDARY OVER THE
LOWER MO INTO OH VALLEYS...DRIVEN LARGELY BY LOW-LEVEL CONVERGENCE
AND WAA ALONG NOSE OF SWLY...NOCTURNAL LLJ. A CONTINUED VEERING AND
EWD MIGRATION OF LLJ ACROSS THE OH VALLEY SHOULD MAINTAIN SIMILAR
REGIME OVER PORTIONS OF IL/IND THROUGH THE MORNING HOURS WITH THE
POTENTIAL FOR SOME HAIL WITH THE MORE INTENSE STORMS.
DYNAMIC RESPONSE TO APPROACHING MIDLEVEL TROUGH WILL RE-ESTABLISH A
SLY LLJ OVER THE CNTRL/SRN PLAINS SATURDAY...WHICH WILL SERVE TO
ENHANCE THE NWD FLUX OF AN INCREASINGLY MOIST AIR MASS WITH
DEWPOINTS RISING THROUGH THE 50S. THIS MOISTURE COUPLED WITH
DIURNAL HEATING AND RATHER STEEP MIDLEVEL LAPSE RATES OF 7-8 C/KM
WILL RESULT IN A MODERATELY UNSTABLE AIR MASS BY AFTERNOON OVER THE
KS/OK WARM SECTOR WITH MLCAPE APPROACHING 1000 J/KG. HOWEVER...
LATEST MODEL GUIDANCE SUGGESTS THAT INITIAL...SURFACE-BASED STORM
DEVELOPMENT MAY BE DELAYED BY: 1) RESIDUAL CAP ASSOCIATED WITH
EML...AND 2) POTENTIALLY LIMITED BOUNDARY LAYER HEATING DUE TO
THICKER MID AND HIGH CLOUDINESS.
CURRENTLY...IT APPEARS THAT THE HIGHEST PROBABILITY OF STORM
INITIATION WILL BE NEAR OR AFTER 08/00Z ALONG THE I-35/135 CORRIDOR
IN KS AS STRONGER HEIGHT FALLS ASSOCIATED WITH UPPER TROUGH BEGINS
TO ERODE CAP. THIS AREA WILL BE LOCATED TO THE E/NE OF SURFACE
CYCLONE WHERE COMBINATION OF BACKED LOW-LEVEL FLOW AND STRENGTHENING
MID/HIGH-LEVEL WIND FIELDS WILL RESULT IN VERTICAL SHEAR QUITE
SUPPORTIVE OF SUPERCELLS. WHILE LARGE HAIL WILL BE THE PRIMARY
SEVERE WEATHER THREAT...A TORNADO OR TWO WILL BE POSSIBLE WITH ANY
MORE INTENSE/LONG-LIVED STORMS THAT CAN BECOME ESTABLISHED.
STORMS SHOULD GROW UPSCALE INTO CLUSTERS OR A QLCS WITH A SEVERE
HAIL/DAMAGING WIND THREAT DEVELOPING EWD/NEWD ACROSS ERN KS INTO
WRN/NRN MO SATURDAY NIGHT. GIVEN THE PRESENCE OF THE CAP AND
DECREASING LARGE-SCALE FORCING WITH SWD EXTENT...THERE IS SOME
QUESTION AS TO HOW FAR S STORMS WILL DEVELOP ALONG SURGING PACIFIC
FRONT. ATTM...IT DOES APPEAR THAT ISOLATED SEVERE STORMS WILL BE
POSSIBLE AT LEAST INTO PARTS OF N-CNTRL INTO NERN OK DURING THE
LATTER HALF OF THE FORECAST PERIOD.
..MEAD.. 03/06/2009
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