SPC AC 281959
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
ISSUED BY AFWA OFFUTT AIR FORCE BASE BELLEVUE NE
0259 PM CDT WED MAR 28 2007
VALID 282000Z - 291200Z
...THERE IS A MDT RISK OF SVR TSTMS FROM WRN NEBRASKA...THROUGH WRN
KANSAS...WRN OKLAHOMA...AND NW TEXAS...
...THERE IS A SLGT RISK OF SVR TSTMS FROM SD INTO SW TX...
...THERE IS A SLGT RISK OF SVR TSTMS FROM SRN VA INTO NC/NRN SC...
...WIDESPREAD SEVERE THUNDERSTORMS INCLUDING DAMAGING WINDS...VERY
LARGE HAIL AND POSSIBLY STRONG TORNADOES WILL DEVELOP OVER THE
WESTERN HALF OF THE CENTRAL AND SOUTHERN PLAINS LATER TODAY AND
TONIGHT...
...CENTRAL/SRN PLAINS...
STRONG UPPER LOW WILL SHIFT INTO THE CENTRAL ROCKIES AND THEN BECOME
STATIONARY OVERNIGHT. THE ASSOCIATED SURFACE DRY LINE EXTENDS FROM
A LOW OVER FAR NERN CO SWD ALONG THE KS/CO AND TX/NM BORDERS.
WIDESPREAD THUNDERSTORM DEVELOPMENT JUST EAST OF THE DRY LINE IS
EXPECTED IN THE NEXT FEW HOURS AS THE CAP WEAKENS...WITH SUPERCELLS
AND SEVERE WEATHER LIKELY. MLCAPE WILL RANGE FROM 1500-2500 J/KG
ACROSS THE AREA...WHILE LOW LEVEL AND DEEP LAYER SHEAR WILL BE
STRONG ALONG THE DRY LINE DESPITE STRONGEST MID LEVEL JET EXTENDING
NNEWD BEHIND THE DRY LINE OVER CO.
HOW LONG ACTIVITY REMAINS IN THE FORM OF DISCRETE SUPERCELLS REMAINS
HARD TO SAY...AS ACTIVITY WILL LIKELY EVOLVE INTO LINEAR STRUCTURES
AS IT MOVES ENEWD THROUGH THE EVENING. HOWEVER...VERY STEEP LAPSE
RATES AND STRONG SHEAR WILL ENHANCE THE POTENTIAL FOR
SIGNIFICANT/DAMAGING HAIL AND STRONG TORNADOES INTO THE EARLY-MID
EVENING WITH ANY DISCRETE STORMS. WIND DAMAGE THREAT SHOULD ALSO
INCREASE AS LINEAR ORGANIZATION BECOMES MORE PREDOMINANT THIS
EVENING...BUT THIS WILL BE TEMPERED BY SLOW FORWARD MOTION OF THE
CONVECTION DUE TO LINE PARALLEL FLOW. LACK OF EWD PROGRESSION WITH
OVERALL SYSTEM AND NARROW INSTABILITY AXIS SUGGESTS STORMS SHOULD
WEAKEN AS THEY MOVE ACROSS CENTRAL SD/NE/KS/OK LATER THIS EVENING.
NAM AND GFS ARE ALSO INDICATING SECONDARY LOBE OF ENERGY ROTATING
AROUND LARGE UPPER LOW AND INTO NERN NM/SERN CO LATE TONIGHT. THIS
SHOULD SUPPORT DEVELOPMENT OF ANOTHER MCS...POSSIBLY SEVERE...OVER
WRN TX INTO WRN OK/SWRN KS OVERNIGHT.
...SW SD/NW NE...
RUC SOUNDINGS INDICATE AROUND 500-1000 J/KG OF SBCAPE ALONG WITH
150-250 J/KG EFFECTIVE HELICITY AND 60-80 KNOTS OF DEEP LAYER SHEAR
IN PLACE ACROSS THIS AREA. CONVECTION IS CURRENTLY DEVELOPING IN
THE NEBRASKA PANHANDLE AND SUPERCELLS WITH LARGE HAIL AND A FEW
TORNADOES ARE POSSIBLE UNTIL AFTER SUNSET WHEN INSTABILITY WILL
DIMINISH.
...CENTRAL APPALACHIANS INTO NC...
DIFFUSE FRONTAL BOUNDARY IS FOCUSING CONVECTIVE DEVELOPMENT FROM
SOUTHERN VIRGINIA INTO NORTHERN NORTH CAROLINA WHERE MLCAPES ARE
AROUND 1000 J/KG. 25-30 KNOTS OF MID LEVEL FLOW WILL PROVIDE ENOUGH
SHEAR FOR MULTICELLULAR CONVECTIVE MODES WITH LARGE HAIL AND
DAMAGING DOWNBURST WINDS POSSIBLE IN THE STRONGER STORMS.
..AFWA.. 03/28/2007
CLICK TO GET WUUS01 PTSDY1 PRODUCT
NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 0100Z
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