SWODY3
SPC AC 230700
DAY 3 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0200 AM CDT MON APR 23 2007
VALID 251200Z - 261200Z
..THERE IS A SLGT RISK OF SVR TSTMS OVER PARTS OF THE MIDDLE INTO
LOWER MS VALLEY AND LOWER OH VALLEY...
..SYNOPSIS...
LATEST MODEL GUIDANCE REMAINS CONSISTENT IN SUGGESTING THE UPPER LOW
OVER KS/OK WEDNESDAY MORNING WILL GRADUALLY WEAKEN AND EVOLVE INTO
AN OPEN WAVE AS IT TRANSLATES EWD INTO THE MID MS/LOWER OH VALLEYS
THURSDAY MORNING. THOUGH MID AND HIGH-LEVEL WIND FIELDS WILL
CONCURRENTLY WEAKEN THROUGH THE PERIOD...A BELT OF MODERATELY STRONG
FLOW WILL PERSIST FROM THE LOWER MS INTO OH VALLEYS.
IN THE LOW-LEVELS...PRIMARY SURFACE LOW WILL DEVELOP SEWD FROM SERN
KS INTO NERN AR OR WRN TN BY 26/12Z. A SECONDARY LOW WILL DEVELOP
MORE EWD ALONG LOW-LEVEL BAROCLINIC ZONE SITUATED ALONG THE OH RIVER
TO THE MID ATLANTIC COAST BY WEDNESDAY EVENING. MEANWHILE...COLD
FRONT ATTENDANT TO WRN-MOST LOW WILL PUSH SEWD THROUGH THE LOWER MS
VALLEY.
..MIDDLE INTO LOWER MS VALLEY AND LOWER OH VALLEY...
WIDESPREAD TSTM ACTIVITY IS EXPECTED TO BE ONGOING ACROSS THE REGION
WEDNESDAY MORNING...RESULTING IN CONSIDERABLE UNCERTAINTY IN SEVERE
WEATHER POTENTIAL THROUGH THE FORECAST PERIOD.
A MOIST LOW-LEVEL AIR MASS WILL BE IN PLACE WITHIN WARM SECTOR WITH
DEWPOINTS IN THE LOW/MID 60S. WITH THE EXCEPTION OF CLOSE VICINITY
TO UPPER LOW...MID-LEVEL LAPSE RATES WILL NOT BE PARTICULARLY STEEP
AND THIS WILL LIMIT THE DEGREE OF INSTABILITY DEVELOPING BY
AFTERNOON.
IT APPEARS THE MOST LIKELY AREAS FOR SEVERE STORM DEVELOPMENT
WEDNESDAY WILL BE: 1) AHEAD OF SURFACE LOW AND ALONG WARM OR
QUASI-STATIONARY BOUNDARY OVER SRN MO AND AR EWD INTO THE LOWER OH
VALLEY WHERE LOW-LEVEL CONVERGENCE WILL BE MAXIMIZED AND VERTICAL
SHEAR IS SUFFICIENTLY STRONG FOR ORGANIZED SEVERE STORMS. AND...2)
ALONG LEADING EDGE OF EXPECTED...PRE-FRONTAL MCS WHICH WILL LIKELY
PERSIST THROUGH THE PERIOD OVER THE LOWER MS VALLEY. GIVEN THE POOR
LAPSE RATE...A FEW TORNADOES AND LOCALLY DAMAGING WINDS APPEAR TO BE
THE PRIMARY SEVERE WEATHER THREATS.
..MIDDLE OH VALLEY EWD TO THE MID ATLANTIC COAST...
LOW-LEVEL MOISTURE IS FORECAST TO INCREASE THROUGH THE PERIOD ALONG
AND TO THE S OF LOW-LEVEL BOUNDARY STRETCHED W-E THROUGH THE REGION.
LAPSE RATES WILL REMAIN RELATIVELY POOR HERE AS WELL...THOUGH THE
INCREASE IN BOUNDARY LAYER MOISTURE WILL SUPPORT POCKETS OF WEAK
INSTABILITY. GIVEN THE RELATIVELY STRONG VERTICAL SHEAR
FORECAST...POTENTIAL WILL EXIST FOR A FEW ORGANIZED STORMS WEDNESDAY
AFTERNOON INTO EVENING INVOF THIS BOUNDARY...ESPECIALLY NEAR AND
AHEAD OF SECONDARY SURFACE LOW DEVELOPING EWD.
.MEAD.. 04/23/2007
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