Jan 20, 2017 1630 UTC Day 1 Convective Outlook
Updated: Fri Jan 20 16:31:57 UTC 2017 (20170120 1630Z Day 1 shapefile | 20170120 1630Z Day 1 KML)
Probabilistic to Categorical Outlook Conversion Table
Categorical Graphic
20170120 1630 UTC Day 1 Outlook Graphic
Day 1 Risk Area (sq. mi.) Area Pop. Some Larger Population Centers in Risk Area
ENHANCED 19,736 1,172,754 Jackson, MS...Hattiesburg, MS...Clinton, MS...Pearl, MS...Brandon, MS...
SLIGHT 89,002 12,016,210 Houston, TX...New Orleans, LA...Baton Rouge, LA...Mobile, AL...Pasadena, TX...
MARGINAL 58,563 20,377,892 Los Angeles, CA...San Diego, CA...Long Beach, CA...Santa Ana, CA...Anaheim, CA...
Probabilistic Tornado Graphic
20170120 1630 UTC Day 1 Tornado Probabilities Graphic
Probability of a tornado within 25 miles of a point.
Hatched Area: 10% or greater probability of EF2 - EF5 tornadoes within 25 miles of a point.
Day 1 Tornado Risk Area (sq. mi.) Area Pop. Some Larger Population Centers in Risk Area
5 % 75,417 6,726,567 New Orleans, LA...Baton Rouge, LA...Mobile, AL...Jackson, MS...Metairie, LA...
2 % 40,417 10,618,577 Houston, TX...Long Beach, CA...Huntington Beach, CA...Oxnard, CA...Oceanside, CA...
Probabilistic Damaging Wind Graphic
20170120 1630 UTC Day 1 Damaging Wind Probabilities Graphic
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.) Area Pop. Some Larger Population Centers in Risk Area
30 % 19,088 1,161,042 Jackson, MS...Hattiesburg, MS...Clinton, MS...Pearl, MS...Brandon, MS...
15 % 89,031 11,989,859 Houston, TX...New Orleans, LA...Baton Rouge, LA...Mobile, AL...Pasadena, TX...
5 % 32,182 18,482,348 Los Angeles, CA...San Diego, CA...Long Beach, CA...Santa Ana, CA...Anaheim, CA...
Probabilistic Large Hail Graphic
20170120 1630 UTC Day 1 Large Hail Probabilities Graphic
Probability of hail 1" or larger within 25 miles of a point.
Hatched Area: 10% or greater probability of hail 2" or larger within 25 miles of a point.
Day 1 Hail Risk Area (sq. mi.) Area Pop. Some Larger Population Centers in Risk Area
SIG SEVERE 49,365 8,712,527 Houston, TX...Baton Rouge, LA...Pasadena, TX...Lafayette, LA...Beaumont, TX...
15 % 98,691 12,529,354 Houston, TX...New Orleans, LA...Baton Rouge, LA...Mobile, AL...Jackson, MS...
5 % 60,378 4,448,427 Birmingham, AL...Montgomery, AL...Tuscaloosa, AL...Hoover, AL...Pensacola, FL...
   SPC AC 201631

   Day 1 Convective Outlook CORR 1
   NWS Storm Prediction Center Norman OK
   1031 AM CST Fri Jan 20 2017

   Valid 201630Z - 211200Z

   ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS TONIGHT OVER
   PARTS OF SOUTHERN MS AND CENTRAL LA...

   ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER MUCH OF THE
   LOWER MS VALLEY REGION AND ADJACENT AREAS...

   ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM THE MIDDLE
   TX GULF COAST INTO PARTS OF AL/FL...

   ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ALONG THE
   SOUTHERN CA COAST...

   CORRECTED FOR THUNDER OUTLOOK LINES

   ...SUMMARY...
   Severe storms will develop this evening and spread across the lower
   Mississippi Valley tonight through Saturday morning, with a few
   tornadoes, large hail, and damaging winds all possible. Strong
   thunderstorms with at least some severe-weather potential are also
   possible near the southern California coast this afternoon.

   ...Lower Mississippi Valley...
   The latest surface analysis shows a weak warm front extending from
   just off the upper TX Gulf Coast into southern LA/MS.  This boundary
   will likely be the main focus for strong to severe storms later this
   afternoon and tonight.  Model solutions suggest that activity will
   first form along or just north of the boundary near HOU/VCT later
   this afternoon and spread east-northeastward during the evening. 
   Relatively steep mid level lapse rates and sufficient deep layer
   shear suggest the potential for rotating storms capable of large
   hail and gusty winds.  Very large hail is possible in the stronger
   cells as they track eastward into LA.

   Overnight, a consensus of 12z solutions indicates that the
   convection tracking eastward across LA will coalesce into a bowing
   complex that tracks across southern MS.  Meanwhile the NAM/RAP/HRRR
   solutions indicate a strengthening low-level jet and low-level
   cyclogenesis occurring.  Low level vertical shear profiles will also
   strengthen over this area, posing some risk of isolated tornadoes. 
   These trends suggest an enhanced risk of locally damaging winds, so
   have added an ENH area for this scenario.

   ...Coastal Southern California...
   Radar and satellite loops show several bands of showers spreading
   eastward and inland into southern CA.  This pattern will persist
   into the afternoon, when a combination of daytime heating and
   cooling mid level temperatures will result in marginal CAPE values
   and scattered thunderstorm activity.  Strong mid and low level
   winds, combined with some orographically induced veering, may result
   in a marginal risk of gusty/damaging winds and/or a brief tornado.

   ..Hart.. 01/20/2017

   NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 2000Z