SWODY1
SPC AC 071239
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0639 AM CST MON JAN 07 2008
VALID 071300Z - 081200Z
..THERE IS A SLGT RISK OF SVR TSTMS OVER PARTS OF THE LOWER AND
MIDDLE MS VALLEY...
MORNING WATER VAPOR IMAGERY SHOWS BROAD UPPER TROUGH OVER THE
WESTERN STATES...WITH STRONG SHORTWAVE TROUGH MOVING EASTWARD ACROSS
SRN CA/NV. THIS FEATURE IS FORECAST TO AMPLIFY AND MOVE INTO THE
SOUTHERN PLAINS BY TONIGHT. MEANWHILE...A SURFACE LOW IS EXPECTED
TO DEVELOP OVER THE TX PANHANDLE THIS AFTERNOON AND TRACK
NORTHEASTWARD INTO MO/IL BY 08/12Z.
..LOWER/MID MS VALLEY TONIGHT...
MOIST AND MARGINALLY UNSTABLE AIR MASS IS STREAMING NORTHWARD THIS
MORNING ACROSS THE SOUTHERN PLAINS AND LOWER MS VALLEY. STRONG
SOUTHWESTERLY LOW LEVEL WINDS THROUGH THE FORECAST PERIOD WILL
MAINTAIN SURFACE DEWPOINTS IN THE UPPER 50S AND LOWER 60S FROM
CENTRAL MO/IL SOUTHWARD. THIS WILL YIELD MUCAPE VALUES OF 500-1000
J/KG THROUGHOUT THIS REGION. COMBINATION OF COOLING ALOFT AND LARGE
SCALE FORCING ASSOCIATED WITH APPROACHING UPPER TROUGH WILL HELP TO
INITIATE SCATTERED THUNDERSTORMS OVER EASTERN OK/WESTERN
AR/SOUTHWEST MO AFTER DARK THIS EVENING. THESE STORMS ARE LIKELY TO
SLOWLY INCREASE IN COVERAGE AND INTENSITY THROUGH THE NIGHT AS THEY
TRACK NORTHEASTWARD ACROSS THE MID MS VALLEY. FORECAST SOUNDINGS
OVER PARTS OF MO/AR INDICATE VERY FAVORABLE LOW LEVEL AND DEEP LAYER
VERTICAL SHEAR PROFILES FOR ORGANIZED SUPERCELLS AND POSSIBLE
TORNADOES /EFFECTIVE HELICITY OF 300-500 M2/S2 AND 6KM BULK SHEAR OF
50-60 KNOTS/. SREF GUIDANCE...NAM...AND EXPERIMENTAL MESOSCALE
MODELS INDICATE THE POTENTIAL FOR AN ENHANCED AREA OF SEVERE THREAT
AFTER MIDNIGHT OVER PARTS OF NORTHERN AR/SOUTHERN MO...WHERE HIGHER
WIND PROBABILITIES AND A LARGER 5% TORNADO RISK AREA HAS BEEN
INCLUDED.
..IA/WI/IL THIS MORNING...
ISOLATED STRONG/SEVERE THUNDERSTORMS ARE OCCURRING THIS MORNING OVER
PARTS OF EASTERN IA. THESE STORMS ARE NEAR NOSE OF 40-50 KNOT
SOUTHWESTERLY LOW LEVEL JET WHERE WARM ADVECTION IS MAXIMIZED. 12Z
DVN SOUNDING SHOWS SUFFICIENT ELEVATED CAPE AND DEEP LAYER SHEAR FOR
A CONTINUED RISK OF ISOLATED LARGE HAIL AS STORMS TRACK ACROSS PARTS
OF SOUTHERN WI AND NORTHERN IL THIS MORNING.
.HART.. 01/07/2008
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