Saturday, June 2, 2007

DAY1SVR: Day 1 Convective Outlook

ACUS01 KWNS 022001
SWODY1
SPC AC 021959

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0259 PM CDT SAT JUN 02 2007

VALID 022000Z - 031200Z

..THERE IS A SLGT RISK OF SVR TSTMS ACROSS PORTIONS OF THE SRN
PLAINS...

..THERE IS A SLGT RISK OF SVR TSTMS ACROSS PARTS OF THE UPR MS
VLY...

..THERE IS A SLGT RISK OF SVR TSTMS ACROSS PARTS OF ERN NY AND NEW
ENGLAND...

..SRN PLAINS...
19Z MESOANALYSIS PLACES A WEAK FRONT FROM NEAR KTUL-KFDR-KTCC.
ALONG/S OF THIS FRONT...BOUNDARY LAYER HAS WARMED CONSIDERABLY TDY
WITH MLCAPES 1500-2000 J/KG. VSBL SATL SHOWS CU FIELD SPROUTING
VCNTY THE BOUNDARY WITH CB/S INCREASING OVER THE HIGHER TERRAIN OF
CO/NM. SUBSIDENCE IN WAKE OF THE MCV OVER ARKLATEX WILL RELAX
SUFFICIENTLY BY LATE AFTN FOR PSBL ISOLD TSTM INITIATION OVER
CNTRL/SRN OK AND/OR N TX. BULK SHEAR IS RATHER WEAK IN THIS
AREA...BUT ISOLD LARGE HAIL/DMGG WIND GUSTS WILL BE POSSIBLE.

MEANWHILE...MORE SUBSTANTIAL STORMS WILL EVOLVE FARTHER W...BOTH
FROM HIGHER TERRAIN CB/S AND ALONG BOUNDARIES ACROSS THE TX PNHDL.
BOUNDARY LAYER FLOW...ALBEIT WEAK AT MID-AFTN...IS EXPECTED TO
BECOME SELY AND INCREASE LATER THIS AFTN TOPPED BY MID-LEVEL NWLY
FLOW OF 25-30 KTS. THIS WILL BOOST EFFECTIVE SHEAR INTO THE
SUPERCELL RANGE WITH LARGE HAIL AND PERHAPS AN ISOLD TORNADO PSBL.
FARTHER S...CINH WAS STRONGER AND EARLY DAY CLOUDS HAVE DAMPENED THE
TEMPERATURE INCREASE THIS AFTN. THUS...TSTMS WILL EITHER WAIT UNTIL
LATE AFTN/EARLY EVE TO DEVELOP FARTHER S ALONG THE SERN NM/SWRN TX
MOUNTAINS OR HOLD OFF ALTOGETHER. BUT...GIVEN A STORM...HIGH LEVEL
FLOW WAS STILL STRONG AND SUPERCELLS WITH LARGE HAIL/ISOLD TORNADOES
WILL BE PSBL.

LLJ IS EXPECTED TO REMAIN SOMEWHAT ANEMIC OVERNIGHT...BUT THE
INCREASING NWLY COMPONENT TO THE STEERING CURRENT MAY YIELD A SMALL
MCS THAT ROLLS SEWD FROM SERN CO/NERN NM SEWD INTO THE TX PNHDL
LATER THIS EVE WITH ATTENDANT THREATS FOR DMGG WINDS/HAIL. ACTIVITY
WILL LIKELY WEAKEN BY 12Z OVER THE LOW ROLLING PLAINS OF TX.

..UPR MS VLY...
CENTER OF STACKED LOW WAS OVER SCNTRL MN AT 19Z. A BROAD MID-LEVEL
DRY SLOT ALONG ERN PERIPHERY OF THIS CYCLONE FROM CNTRL/SRN MN INTO
IA HAS FILLED WITH CB/S THIS AFTN AS MID MINUS-TEENS H5 TEMPERATURES
SPREAD ATOP NEAR 60 DEG F SFC DEW POINTS. SATL SHOWS FUZZY TOPS TO
THE STORMS...INDICATIVE OF LOW-TOPPED AND WEAKLY SHEARED STORMS.
ISOLD TORNADOES WILL REMAIN POSSIBLE WITH THE STORMS...PARTICULARLY
WHERE THE NEAR SFC FLOW REMAINS BACKED FROM NEAR THE KMSP METRO AREA
SEWD INTO WRN WI/SERN MN. STORMS THAT DEVELOP IN THIS SUBTLE
LOW-LEVEL CONVERGENCE ZONE WILL HAVE AVAILABILITY TO MODEST
LOW-LEVEL SRH...BUT WINDOW OF OPPORTUNITY FOR TORNADOES WOULD BE
VERY BRIEF AS THE LOW-LEVEL FLOW VEERS QUICKLY THIS EVENING OWING TO
THE INCREASING FORWARD EJECTION OF THE UPR SYSTEM TO THE EAST.
OTHERWISE...DAMAGING WIND GUSTS AND PERHAPS HAIL MAY ACCOMPANY THE
STRONGER STORMS.

..ERN NY AND CNTRL/SRN NEW ENGLAND...
TEMPERATURES WARMING WELL INTO THE 70/80S AND SFC DEW POINTS IN THE
60S HAVE CONTRIBUTED TO MLCAPES TO 750-1500 J/KG ACROSS THE REGION
THIS AFTN. AREA REMAINS ALONG SRN EDGE OF STRONGER FLOW ALOFT AND
WITH AN APPROACHING WEAK H5 WAVE OVER SERN ONT...STRONG TSTMS HAVE
DEVELOPED ALONG THE HIGHER TERRAIN/BOUNDARIES. BELT OF 30-40 KTS OF
6KM BULK SHEAR EXTENDS SWD INTO CNTRL PARTS OF NY AND NEW ENGLAND
WITH MUCH WEAKER FLOW EXISTING AT FARTHER S LATITUDES /IE
MASON-DIXON LINE/. AS A RESULT...STRONGEST STORMS...POSSIBLY
BRIEFLY ATTAINING SUPERCELLULAR STATUS...WILL LIKELY OCCUR ACROSS
ERN/NRN NY INTO PARTS OF VT/NH AND MA THROUGH EARLY EVE. DAMAGING
WIND GUSTS AND LARGE HAIL WILL ACCOMPANY THE STRONGEST STORMS.

..SERN ATLC COAST TONIGHT...
REMNANT TS BARRY WILL MOVE NNEWD TO KJAX THIS EVE AND THEN INTO ERN
SC BY 12Z SUNDAY. STRONGEST LOW-LEVEL SHEAR WILL BE
CONFINED TO THE AREA IMMEDIATELY E/NE OF THE SURFACE CENTER WHICH
MAY SPREAD BACK ONSHORE LATER TONIGHT OVER FAR ERN NC COINCIDENT
WITH INTRUSION OF A MORE TROPICAL BOUNDARY LAYER. THUS...LOW
TORNADO PROBABILITIES WILL BE MAINTAINED.

..SRN CASCADES...
TSTMS WILL LIKELY DEVELOP ALONG THE HIGHER CREST OF THE SRN CASCADES
LATE THIS AFTN AND PERSIST INTO THE EVE HOURS IN FAVORABLE STEEP
LAPSE RATE/MODESTLY MOIST ENVIRONMENT. WEAK STEERING FLOW WILL KEEP
STORMS MAINLY ALONG THE MOUNTAINS WITH PERHAPS PULSE-TYPE HAIL/WIND
GUSTS APPROACHING SVR LIMITS.

.RACY.. 06/02/2007

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