Probability of damaging thunderstorm winds or wind gusts of 50 knots or higher within 25 miles of a point. Hatched Area: 10% of greater probability of wind gusts 65 knots or greater within 25 miles of a point.
SPC AC 280055
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0755 PM CDT Sun Aug 27 2017
Valid 280100Z - 281200Z
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
SOUTHEAST TEXAS AND SOUTHWEST LOUISIANA...
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
SOUTHWEST KANSAS...FAR SOUTHEAST COLORADO INTO THE OKLAHOMA AND
TEXAS PANHANDLES...
...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS OUTSIDE OF THE
SLIGHT RISK AREA ACROSS PARTS OF SOUTHEAST TEXAS AND LOUISIANA...
...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS OUTSIDE OF THE
SLIGHT RISK AREA ACROSS PARTS OF THE SOUTHERN AND CENTRAL HIGH
PLAINS...
...SUMMARY...
A few tornadoes are possible along the Upper Texas Coastal Plain
into far southwest Louisiana this evening into tonight. An isolated
threat for wind damage and hail will also be possible from far
southwest Kansas into the Texas Panhandle this evening.
...Southeast Texas/Southern Louisiana...
The National Hurricane Center is forecasting the center of Tropical
Storm Harvey to move slowly southeastward toward the middle coast of
Texas to the southeast of Victoria, Texas tonight. Bands of heavy
rainfall will continue to develop to the north and northeast of
Harvey's center across central and east Texas into Louisiana
tonight. RAP data continues to show a reservoir of moderate
instability across the western Gulf of Mexico with the axis of
strongest instability impinging the coast near the Beaumont/Port
Arthur vicinity, where MLCAPE values are estimated to be around 1500
J/Kg. In addition, the WSR-88D VWP at Lake Charles shows 0-6 km
shear near 40 kt with substantial directional shear in the low to
mid-levels. The Lake Charles wind profile also shows 0-1 km shear of
20-25 kt with 0-3 km storm relative helicity near 250 m2/s2. This
shear environment will continue to support supercells and tornadoes
this evening into the overnight period. The greatest tornado threat
this evening should be in the Beaumont/Port Arthur area where the
combination of instability and shear is maximized. This tornado
threat could move eastward into southwest Louisiana as Harvey moves
slowly southeastward through tonight. Another band of heavy rainfall
just to the northeast of Harvey's center could also affect the
Houston/Galveston vicinity where tornadoes will also be
possible...see MCD 1589.
...Far Southwest Kansas/Texas and Oklahoma Panhandles...
The latest water vapor imagery shows an upper-level ridge over the
western U.S. with northerly flow in the mid-levels across the
central Plains. At the surface, a moist airmass is in place from
southwest Kansas into the Texas Panhandle where the RAP is analyzing
a pocket of moderate instability. A cluster of strong to severe
thunderstorms is ongoing in far southwestern Kansas and in the
western Oklahoma Panhandle near the maximum of instability. Regional
WSR-88D VWPs show backing winds with height but estimate that 0-6 km
shear is still about 35 kts. This may be enough for an isolated
severe threat for a few more hours. Isolated large hail and wind
damage will be possible with storms that rotate and with the
stronger multicells. The severe threat should become marginal late
this evening.
..Broyles.. 08/28/2017
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