SWODY1
SPC AC 020551
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1251 AM CDT TUE OCT 02 2007
VALID 021200Z - 031200Z
..THERE IS A SLGT RISK OF SVR TSTMS FROM PARTS OF THE SRN PLAINS
NEWD INTO THE MID-UPR MS VLY...
..SYNOPSIS...
UPR TROUGH PROGRESSING RAPIDLY INTO THE CNTRL/NRN ROCKIES EARLY
TODAY WILL ACHIEVE A SLIGHT NEGATIVE TILT OVER THE PLAINS AND THEN
EJECT NEWD INTO THE UPR GRTLKS AND UPR MS VLY REGIONS BY EARLY
WEDNESDAY. PRIMARY SFC LOW WILL TRACK NEWD ACROSS MN INTO NWRN
ONTARIO IN TANDEM WITH 120+ METER H5 HEIGHT FALLS. TRAILING THE
LOW...A COLD FRONT WILL SWEEP SEWD FROM THE PLAINS AND INTO THE
MID-UPR MS VLY...OZARKS AND SRN PLAINS BY 12Z WED. PRECEDING THE
FRONT...A PRE-FRONTAL TROUGH WILL EXIST FROM SRN IA SWWD INTO NRN OK
TUESDAY AFTN BEFORE BEING OVERTAKEN BY THE COLD FRONT TUESDAY
EVENING. THE PRE-FRONTAL TROUGH AND COLD FRONT WILL BE THE FOCI FOR
PSBL SVR TSTMS DURING TUESDAY AFTN/EVE FROM THE SRN PLAINS TO THE
UPR MS VLY.
..SRN PLAINS NEWD INTO THE UPR MS VLY...
MID-HIGH LEVEL SUB-TROPICAL CONVEYOR WILL CONTINUE TO STREAM NEWD
INTO THE CNTRL PLAINS AND UPR MS VLY AHEAD OF THE APPROACHING TROUGH
ON TUESDAY. THIS PLUME WILL MODULATE INSOLATION WITHIN THE WARM
SECTOR AND SUPPLY THE PLAINS AND MID-UPR MS VLY WITH RATHER POOR
LAPSE RATES ALOFT. THIS WILL LIKELY MITIGATE OVERALL INSTABILITY
VALUES... PARTICULARLY ACROSS THE UPR MS VLY WHERE MLCAPES WILL ONLY
REACH INTO THE 500-750 J/KG RANGE. FARTHER S...INSOLATION WILL
LIKELY BE MORE SUBSTANTIAL AND TRANSPORT OF MID-UPR 60S SFC DEW
POINTS NWD FROM THE SRN PLAINS TOWARD SRN IA WILL CONTRIBUTE TO
MLCAPES OF 1500-2000 J/KG.
SPEED MAXIMUM EMBEDDED WITHIN THE AFOREMENTIONED HIGH-LEVEL
CONVEYOR...CURRENTLY CROSSING THE SRN HIGH PLAINS...WILL SUPPORT
SPORADIC TSTMS...LIKELY REACHING THE UPR MS VLY BY AFTN. AS
STRONGER LARGE SCALE ASCENT ASSOCD WITH THE PRIMARY TROUGH ARRIVES
BY MID-AFTN...TSTMS WILL INTENSIFY AND/OR DEVELOP ALONG THE SRN EDGE
OF THESE STORMS FROM SRN IA SWWD INTO ERN KS AND NCNTRL OK. THE
STRONGER STORMS WILL LIKELY FAVOR THE PRE-FRONTAL TROUGH...LIKELY TO
RESIDE FROM NCNTRL OK NEWD INTO ERN KS AND NWRN MO.
WSWLY FLOW WILL BE MORE UNIDIRECTIONAL AT FARTHER N LATITUDES AND
SHOULD FAVOR A FASTER EVOLUTION INTO LINE SEGMENTS ACROSS PARTS OF
IA AND NRN MO. FARTHER S...HOWEVER...DIRECTIONAL SHEAR IN THE
LOWEST 3 KM COUPLED WITH STRONGER INSTABILITY MAY PROMOTE MORE
DISCRETE SUPERCELL STRUCTURES FOR A FEW HOURS LATE TUESDAY AFTN/EVE
FROM NCNTRL/NERN OK NEWD INTO NCNTRL MO. GIVEN POOR LAPSE RATES
ALOFT...HAIL DOES NOT APPEAR TO BE THE PRIMARY SVR CONCERN.
BUT...DMGG WINDS WILL BE A THREAT WITH BOWING LINE SEGMENTS. MORE
DISCRETE STORMS MAY PRODUCE A COUPLE OF TORNADOES...PRIMARILY ACROSS
SERN KS INTO CNTRL MO...ALONG NRN PERIPHERY OF MORE SUBSTANTIAL
LOW-LEVEL MOISTURE. FARTHER N...BOW HEAD TYPE TORNADOES WILL ALSO
BE POSSIBLE INTO THE ECNTRL IA/NWRN IL AREA.
NRN PORTION OF THE EVOLVING SQUALL LINE WILL LIKELY PEAK IN THE
EARLY EVENING AS IT MOVES INTO SRN WI...WRN IL AND ECNTRL MO.
ACTIVITY SHOULD QUICKLY DIMINISH LATER IN THE EVENING AS IT OUTRUNS
THE INSTABILITY AXIS. PROBABILITIES FOR DMGG WIND GUSTS/HAIL WILL
LINGER LONGER FARTHER TO THE SW FROM PARTS OF OK NEWD INTO THE
OZARKS THROUGH LATE EVENING.
..CNTRL/SRN FL...
UPR LOW FEATURE OVER THE SERN GULF OF MEXICO WILL CONTINUE WWD
TUESDAY. DEEP LAYER SLY FLOW ON THE E SIDE OF THIS FEATURE WILL
ADVECT TROPICAL MOISTURE NWD INTO CNTRL/SRN FL ALONG WITH BANDS OF
TSTMS. MODEST UPR LVL WINDS WILL FAVOR VENTING AND AUGMENTATION OF
UPDRAFTS POSSIBLY YIELDING STG STORMS. THOUGH LOW-LEVEL SHEAR
PROFILES WILL NOT BE PARTICULARLY STRONG...BRIEF AND ISOLD TORNADOES
WILL BE PSBL ALONG WITH A LOW PROBABILITY FOR A DMGG WIND GUST OR
TWO.
.RACY/CROSBIE.. 10/02/2007
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