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.
Day 1 Wind Risk
Area (sq. mi.)
Some Larger Population Centers in Risk Area
Memphis, TN...Shreveport, LA...Little Rock, AR...Tyler, TX...Longview, TX...
SPC AC 260548
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1248 AM CDT Wed Apr 26 2017
Valid 261200Z - 271200Z
...THERE IS A MODERATE RISK OF SEVERE THUNDERSTORMS ACROSS THE
...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS FROM NORTHEAST
TEXAS TO EXTREME SOUTHERN MISSOURI...
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM SOUTHERN
LOUISIANA TO SOUTHEAST MISSOURI...
...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM THE UPPER
TEXAS COAST TO NORTHWEST INDIANA...
Severe thunderstorms are expected across the Lower Mississippi
Valley Wednesday. Tornadoes, large hail, and damaging winds should
focus from northeast Texas across southern Arkansas and northern
Louisiana primarily during the afternoon hours. Isolated severe
thunderstorms may extend as far north as Illinois and into the
central Gulf States during the overnight hours.
...Lower MS Valley...
Early-morning water vapor/radar imagery depict a well defined upper
circulation over northeast NM shifting east-southeast in line with
late-evening model guidance. High-level flow is increasing across
the southern Rockies and 500mb speeds on the order of 75kt will
translate into central TX later today. This feature will induce
significant mid-level height falls across the lower MS Valley and
encourage strengthening LLJ over LA/AR by 18z.
26/00z observed soundings across TX depict very steep mid-level
lapse rates, on the order of 8.5-9 c/km, and this lapse-rate plume
should spread across the Arklatex region prior to convective
development. Current thinking is thunderstorms will struggle to
develop across much of TX due to significant CINH and this should
allow air mass to destabilize across the MDT risk region as surface
temperatures warm to near 80F with near 70F dew points. Forecast
NAM soundings by early afternoon depict SBCAPE in excess of 3000
J/kg across northeast TX where convection should initiate prior to
frontal passage. Shear profiles strongly favor supercells, though
mid-level height falls and slightly backed mid-level flow could
eventually lead to a more complex MCS as the trough ejects toward
the Mid-south after dark. Very large hail could accompany the
supercells across the Arklatex region and tornadoes appear possible.
Strong/severe convection should spread into the central Gulf States
during the evening/overnight hours as entrance region of upper jet
shifts into this region during the latter half of the period.
...Mid MS Valley...
Southwest-northeast oriented squall line has evolved from eastern OK
into southwest MO early this morning. Models suggest this activity
should be ongoing at the beginning of the period but possibly a bit
farther east than deterministic data would suggest. This early-day
convection will certainly disrupt and overturn buoyancy across much
of the mid Mississippi Valley. It's not entirely clear how unstable
MO/IL region will be ahead of this activity and forecast soundings
suggest poor lapse rates and weak buoyancy. For these reasons have
lowered severe probs across much of IL/MO due to limited
instability. Otherwise, forced squall line could certainly produce
isolated severe wind gusts but the more robust convection should
remain across the Ozark Plateau and points south.
NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 1300Z