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
New Orleans, LA...Baton Rouge, LA...Mobile, AL...Jackson, MS...Metairie, LA...
SPC AC 210058
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0658 PM CST Fri Jan 20 2017
Valid 210100Z - 211200Z
...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
SOUTHERN AND CENTRAL LA/MS...AND SOUTHWEST AL...
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS EXTENDING FROM
SOUTHEAST TX ACROSS THE LOWER MS VALLEY INTO AL AND THE FL
...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS SURROUNDING THE
Scattered severe storms are expected to continue developing this
evening across southeast Texas, and spread across the lower
Mississippi Valley and into Alabama and the Florida Panhandle
tonight through Saturday morning. A few tornadoes, some of which
could be strong, large hail, and damaging winds will all be
Reminder: This Day 1 Convective Outlook will be valid THROUGH 12Z
Saturday (7 AM EST/6 AM CST). An upcoming Day 1 Convective Outlook
will be issued around 06Z (1 AM EST/Midnight CST), which will be
valid BEGINNING at 12Z Saturday, and continuing through 12Z Sunday.
...Southeast TX into the Lower MS Valley and Adjacent Gulf Coast
A cluster of thunderstorms has developed across the Houston metro
area over the past several hours along a sea breeze as large-scale
ascent associated with an upstream shortwave trough overspreads this
region. This activity is expected to continue northeastward/eastward
across the lower Sabine River valley through the evening. Better
low-level moisture characterized by mid 60s to lower 70s dewpoints
currently resides near/along coastal LA/MS/AL and the western FL
Panhandle. This moisture will likely move northward into central
LA/MS/AL as an effective warm front through 12Z Saturday as a 40-50
kt low-level jet strengthens across this region.
Overall thinking regarding convective evolution through this
evening/overnight and into early Saturday morning remains generally
unchanged from the prior outlook. Upscale growth of initial
cluster/discrete development in southeast TX/southwest LA appears
probable given the strength of the low-level jet and large-scale
ascent associated with a 120+ kt upper jet moving over the lower MS
Valley. While large hail may be an initial threat given steep
mid-level lapse rates, damaging winds would appear to be the greater
concern with time as this line of thunderstorms moves eastward
across southern/central LA/MS and into southwest AL overnight. Some
adjustments have been made to the 30% wind probabilities and
corresponding Enhanced Risk area to account for a slightly faster
eastward progression of this line per most recent convection-
allowing model guidance.
In addition, a 10% tornado probability area has been included for
parts of southern LA/MS and far southwest AL, including the Mobile
metro area. There will be a greater potential for discrete supercell
development with southward extent ahead of the previously mentioned
line of thunderstorms. Forecast soundings across this region suggest
that any tornadoes that do form in this environment could be strong
with southwesterly winds around 850 mb strengthening to around 50 kt
overnight, and corresponding effective SRH in excess of 300 m2/s2.
For additional information on the near-term severe threat (through
about 0230Z) across southeast TX through southwest LA, see recently
issued Mesoscale Discussion 80.
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NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 0600Z