SWODY1
SPC AC 240609
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0109 AM CDT TUE APR 24 2007
VALID 241200Z - 251200Z
..THERE IS A MDT RISK OF SVR TSTMS ACROSS CENTRAL AND ERN
KANSAS...CENTRAL AND ERN OKLAHOMA...NRN AND NERN TEXAS...PARTS OF
WRN MISSOURI AND FAR WRN ARKANSAS...
..THERE IS A SLGT RISK OF SVR TSTMS SURROUNDING THE MODERATE RISK
FROM THE CENTRAL AND SRN PLAINS EWD TO THE MID MS/LOWER OH
VALLEYS...
..OUTBREAK OF SEVERE STORMS CAPABLE OF TORNADOES /A FEW
STRONG/...VERY LARGE/DESTRUCTIVE HAIL AND DAMAGING WINDS CONTINUES
TO APPEAR LIKELY TODAY THROUGH TONIGHT ACROSS ERN PARTS OF
CENTRAL/SRN PLAINS...
..SYNOPSIS...
00Z NAM/GFS REMAIN CONSISTENT WITH EWD PROGRESSION OF MID AND UPPER
LEVEL LOW FROM CO/NM INTO CENTRAL/SRN PLAINS BY 12Z WEDNESDAY. IN
THE LOW LEVELS...ATTENDANT SURFACE LOW IS EXPECTED TO DEEPEN DURING
MUCH OF THE FORECAST PERIOD AS IT TRACKS ESEWD FROM SERN CO TO ALONG
THE SOUTH CENTRAL KS/NRN OK BORDER REGION BY WEDNESDAY MORNING.
WARM FRONT INITIALLY EXTENDING EWD FROM SURFACE LOW THROUGH CENTRAL
KS TO SRN MO AND LOWER OH VALLEY WILL RETREAT STEADILY NWD...
STRETCHING FROM NRN KS EWD THROUGH NRN MO TO CENTRAL IL AND SRN IND
BY LATE THIS AFTERNOON/EVENING. MEANWHILE...DRY LINE IS EXPECTED TO
ADVECT/MIX RAPIDLY NE AND E TO VICINITY OF CENTRAL/SRN KS SWD ALONG
OR JUST W OF I-35 CORRIDOR IN OK/N TX AND THEN EXTEND SWWD TO NEAR
DRT BY MID AFTERNOON.
..CENTRAL/SRN PLAINS...
EXTENSIVE AREA OF CLOUDS CURRENTLY LOCATED ACROSS THE ERN HALF OF
THE CENTRAL/SRN PLAINS IS EXPECTED TO SHIFT EWD AWAY FROM THE WARM
SECTOR ALLOWING FOR STRONG SURFACE HEATING TODAY. THIS COUPLED WITH
SLY LOW LEVEL FLOW ADVECTING RICH MOISTURE NWD WILL SUPPORT MODERATE
INSTABILITY ALONG/E OF DRY LINE.
AT 12Z TODAY...AN AREA OF ELEVATED...AND POTENTIALLY SEVERE... TSTMS
ARE EXPECTED TO BE ONGOING WITHIN STRONG LOW-LEVEL WAA REGIME NEAR
AND N OF WARM FRONT ACROSS NRN KS INTO SRN NEB. THIS ACTIVITY
SHOULD PERSIST THROUGH MUCH OF THE MORNING INTO EARLY AFTERNOON
WITHIN CONTINUED ZONE OF STRONG WAA NEAR AND N OF RETREATING WARM
FRONT. SURFACE-BASED CONVECTION MAY TEND TO DEVELOP FAIRLY EARLY IN
THE DAY OVER PARTS OF WRN INTO CNTRL KS AS LARGE-SCALE FORCING FOR
ASCENT ACTS ON A WEAKLY CAPPED AIR MASS. DESPITE BEING EARLY IN THE
DIURNAL HEATING CYCLE...FORECAST SOUNDINGS INDICATE MODERATE
INSTABILITY AND STRONG DEEP LAYER AND LOW LEVEL SHEAR VALUES
SUPPORTIVE OF SUPERCELLS PRODUCING TORNADOES AND LARGE HAIL. TSTMS
ARE EXPECTED TO INCREASE IN AREAL COVERAGE INTO THE
AFTERNOON/EVENING ACROSS CNTRL/ERN KS AS DRYLINE SURGES
NEWD/EWD...AND ALSO ALONG WARM FRONT WITH A CONTINUING THREAT OF
SUPERCELLS PRODUCING TORNADOES /A FEW STRONG/ AND VERY
LARGE/DESTRUCTIVE HAIL.
FARTHER S...MODELS ARE NOT AS CONSISTENT WITH TIMING OF TSTM
INITIATION SWD ALONG DRY LINE INTO CENTRAL OK/N TX...GIVEN STRONGER
CAP ACROSS THIS REGION. DESPITE THIS INCONSISTENCY...PATTERN
RECOGNITION SHOWING STRONG HEIGHT FALLS AHEAD OF MID/UPPER LEVEL LOW
AND STRENGTHENING WIND FIELDS WITHIN MOISTENING AIR MASS SUGGESTS
CONVECTIVE DEVELOPMENT WILL LIKELY OCCUR SWD ALONG DRY LINE BY MID
TO LATE AFTERNOON. MOST OF THE MODELS EXCEPT FOR THE NAM SUGGEST
TSTM INITIATION MAY NOT OCCUR UNTIL JUST AFTER 00Z. DESPITE THESE
TIMING DIFFERENCES...STRONG DEEP LAYER AND LOW LEVEL SHEAR VALUES
WILL BE SUPPORTIVE OF TORNADIC SUPERCELLS ALSO PRODUCING VERY LARGE
AND DESTRUCTIVE HAIL. THIS POTENTIAL WILL LIKELY DEVELOP SSWWD
ALONG DRY LINE INTO CENTRAL/SWRN TX TO NEAR DRT.
POTENTIAL EXISTS FOR TORNADIC SUPERCELLS TO PERSIST EWD INTO ERN
KS/ERN OK INTO WRN MO/AR THIS EVENING/TONIGHT AS MID/UPPER LEVEL LOW
SHIFTS EWD. MEANWHILE...AS SRN EXTENT OF MID/UPPER LEVEL TROUGH
SPREADS EWD THROUGH SRN/SERN OK AND MUCH OF CENTRAL/ERN TX
TONIGHT...MODELS SUGGEST AN INCREASING POTENTIAL FOR LINEAR
STRUCTURE WITH BOWING SEGMENTS PRODUCING DAMAGING WINDS TOWARD THE
ARKLATEX AND ERN/S CENTRAL TX.
..LOWER MO/MID MS VALLEYS IN THE OH VALLEY...
SSWLY LLJ...ASSOCIATED WITH SUB-TROPICAL SHORT WAVE TROUGH...NOW
LOCATED OVER CENTRAL/NRN TX INTO SRN OK...IS EXPECTED TO TRANSLATE
EWD RESULTING IN MOISTURE ADVECTION INTO THE MID MS/LOWER OH VALLEYS
TODAY. WEAKER MID LEVEL LAPSE RATES SHOULD TEND TO TEMPER THE
DEGREE OF INSTABILITY THAT DEVELOPS BY THIS AFTERNOON ACROSS THIS
REGION...DESPITE SURFACE DEWPOINTS EXPECTED TO BE IN THE LOWER-MID
60S. TSTMS SHOULD DEVELOP IN THE VICINITY OF THE WARM FRONT FROM
SRN MO TO WRN KY THIS AFTERNOON...WITH EFFECTIVE BULK SHEAR VALUES
SUPPORTING PRIMARILY MULTICELLS...THOUGH A FEW SUPERCELLS WILL ALSO
BE POSSIBLE.
.PETERS.. 04/24/2007
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