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Replies to post #140703 on Tornado Alley (PROG)
05/22/11 8:55 PM
http://www.spc.noaa.gov/products/outlook/day1otlk.html [use this link for later Day 1 Outlooks, available at 8a, 11:30a, 3p and 8p CDT]SPC AC 240559
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1259 AM CDT TUE MAY 24 2011
VALID 241200Z - 251200Z
...THERE IS A HIGH RISK OF SVR TSTMS ACROSS PARTS OF SOUTH CENTRAL
AND SOUTHEAST KANSAS SWD INTO PARTS OF CENTRAL AND EASTERN
OKLAHOMA...
...THERE IS A MDT RISK OF SVR TSTMS ACROSS CENTRAL AND SOUTHEAST
KANSAS...CENTRAL AND EASTERN OKLAHOMA...AND INTO WESTERN ARKANSAS...
...THERE IS A SLGT RISK OF SVR TSTMS FROM NEW ENGLAND SWD TO THE
MID-ATLANTIC REGION...AND WWD INTO THE PLAINS...
...SYNOPSIS...
WITH CYCLONIC FLOW ALOFT TO PERSIST ACROSS THE NORTHEAST U.S. AND
ERN CANADA...A STRENGTHENING MID-LEVEL SYSTEM -- ACCOMPANIED BY
70-PLUS KT MID-LEVEL JET -- IS FORECAST TO EMERGE INTO THE CENTRAL
AND SRN PLAINS. BY THE END OF THE PERIOD...A DEEPENING UPPER LOW IS
FORECAST ACROSS THE KS VICINITY -- WITH A 75 KT MID-LEVEL JET AROUND
THE SRN PERIPHERY OF THIS SYSTEM.
AT THE SURFACE...A COLD FRONT WILL CONTINUE ADVANCING ACROSS ERN
CANADA...MOVING EWD INTO NEW ENGLAND THROUGH THE AFTERNOON BUT
BECOMING MORE WASHED OUT ACROSS THE MIDWEST/OH VALLEY WITH TIME.
FARTHER W...A LEE LOW IS FORECAST TO MOVE VERY SLOWLY EWD/NEWD
ACROSS KS/OK...BUT SHOULD STRENGTHEN THROUGH THE AFTERNOON AS THE
UPPER LOW DEEPENS. BY LATE AFTERNOON...A DRYLINE WILL EXTEND SWD
ACROSS CENTRAL OK/CENTRAL TX AND A COMPOSITE WARM FRONT/OUTFLOW
BOUNDARY SHOULD EXTEND SEWD ACROSS SRN KS/ERN OK AND INTO AR. THIS
SURFACE SYSTEM WILL BECOME A FOCUS FOR THE DEVELOPMENT OF A
POTENTIALLY SIGNIFICANT SEVERE WEATHER OUTBREAK FOCUSED ON KS/OK/WRN
AR THROUGH THE AFTERNOON AND EVENING HOURS.
...CENTRAL AND SRN PLAINS...
A REGIONAL OUTBREAK OF SEVERE STORMS -- INCLUDING THE POTENTIAL FOR
VERY LARGE HAIL...DAMAGING WINDS...AND SEVERAL LARGE/STRONG
TORNADOES IS EXPECTED THIS AFTERNOON AND EVENING AS THE POWERFUL
UPPER JET EMERGES INTO THE PLAINS DRIVING SURFACE CYCLOGENESIS.
ELEVATED STORMS MAY BE ONGOING ACROSS PARTS OF NRN KS AND NEB AT THE
START OF THE PERIOD...WHILE A CAPPED WARM SECTOR HINDERS STORM
DEVELOPMENT INTO THE AFTERNOON HOURS. BY MID AFTERNOON...SURFACE
DEWPOINTS IN THE 60S TO NEAR 70 COMBINED WITH DAYTIME HEATING AND AN
EWD SPREAD OF VERY STEEP MID-LEVEL LAPSE RATES ATOP THE WARM SECTOR
WILL RESULT IN A VERY UNSTABLE ENVIRONMENT...WITH 100 MB MIXED-LAYER
CAPE VALUES EXCEEDING 3000 TO 4000 J/KG ACROSS PARTS OF OK/KS AND
INTO WRN AR E OF THE LOW/DRYLINE.
AS THE UPPER JET AND ASSOCIATED/DEEPENING UPPER SYSTEM EMERGE...A
SLOWLY WEAKENING CAP SHOULD RESULT IN STORM INITIATION BY LATE
AFTERNOON...FROM CENTRAL KS SWD INTO CENTRAL TX NEAR THE SURFACE LOW
AND SWD ALONG THE DRYLINE. WITH MODERATE/BACKED LOW-LEVEL FLOW
AHEAD OF THE SURFACE LOW VEERING AND INCREASING RAPIDLY THROUGH THE
LOWER TROPOSPHERE TO SWLY AT 50 TO 60 KT AT MID LEVELS...SHEAR VERY
SUPPORTIVE OF BOTH MID-LEVEL AND LOW-LEVEL ROTATION WILL ALLOW
STORMS TO RAPIDLY BECOME SUPERCELLULAR. VERY LARGE HAIL...DAMAGING
WINDS...AND SEVERAL POTENTIALLY SIGNIFICANT TORNADOES APPEAR LIKELY
AS THE STORMS INCREASE AND SPREAD ACROSS KS/OK INTO WRN AR AND THEN
LATER INTO WRN MO.
WHILE STORMS DEVELOPING SWD ACROSS CENTRAL TX ALONG THE DRYLINE
SHOULD EVENTUALLY BEGIN DIMINISHING DURING THE EVENING AS BOUNDARY
LAYER STABILIZATION/CAPPING BECOME REESTABLISHED...WIDESPREAD STORMS
AND ASSOCIATED SEVERE POTENTIAL WILL CONTINUE INTO THE OVERNIGHT
HOURS ACROSS KS/ERN OK/MO/AR. SLIGHTLY ELEVATED STORMS SHOULD ALSO
INCREASE INTO NEB/IA AND VICINITY...ALONG WITH SOME ACCOMPANYING
SEVERE THREAT.
...NEW ENGLAND SWD TO THE MID-ATLANTIC AND WWD INTO THE OH/TN/MID MS
VALLEYS...
SHOWERS AND SCATTERED THUNDERSTORMS MAY BE ONGOING AT THE START OF
THE PERIOD...AND AS AIRMASS DESTABILIZES AHEAD OF THE SURFACE COLD
FRONT AWAY FROM LINGERING CLOUDS/PRECIPITATION...EXPECT CONVECTION
TO REDEVELOP/INTENSIFY THROUGH THE AFTERNOON.
THE BELT OF STRONGEST FLOW ALOFT IS FORECAST TO REMAIN S OF THE OH
RIVER...BUT INSTABILITY MAY BE MORE LIMITED ACROSS PARTS OF THIS
REGION DEPENDING UPON THE EVOLUTION OF AN ONGOING BOW APPROACHING
THE MID MS VALLEY REGION ATTM. OVERALL...EXPECT BROAD/WIDESPREAD
ZONE OF SEVERE POTENTIAL NEAR AND SE OF THE COLD FRONT...WITH
STRONGEST STORMS WITHIN MULTIPLE BANDS OF CONVECTION CAPABLE OF
PRODUCING HAIL AND DAMAGING WINDS.
..GOSS.. 05/24/2011
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AI
