Apr 21, 2018 0600 UTC Day 2 Convective Outlook
Updated: Sat Apr 21 05:31:43 UTC 2018 (20180421 0600Z Day 2 shapefile | 20180421 0600Z Day 2 KML)
Probabilistic to Categorical Outlook Conversion Table
Categorical Graphic
20180421 0600 UTC Day 2 Outlook Graphic
Day 2 Risk Area (sq. mi.) Area Pop. Some Larger Population Centers in Risk Area
MARGINAL 75,002 5,739,447 New Orleans, LA...Mobile, AL...Jackson, MS...Tallahassee, FL...Metairie, LA...
Probabilistic Graphic
20180421 0600 UTC Day Probabilitic Graphic
Probability of severe weather within 25 miles of a point.
Hatched Area: 10% or greater probability of significant severe within 25 miles of a point.
Day 2 Prob. Risk Area (sq. mi.) Area Pop. Some Larger Population Centers in Risk Area
5 % 74,522 5,696,677 New Orleans, LA...Mobile, AL...Jackson, MS...Tallahassee, FL...Metairie, LA...
   SPC AC 210531

   Day 2 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   1231 AM CDT Sat Apr 21 2018

   Valid 221200Z - 231200Z

   ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS SOUTHEAST
   LA...MUCH OF MS...SOUTHWEST/SOUTHERN AL...AND FL PANHANDLE...

   ...SUMMARY...
   Isolated severe thunderstorms are possible across portions of the
   Southeast states and Florida Panhandle.

   ...Synopsis...
   Upper low, centered over eastern OK at the beginning of the period,
   is expected to move gradually southeastward, reaching northern AL by
   the end of the period. Associated surface low will take a similar
   track with the overall system becoming increasingly vertically
   stacked throughout the day. Widespread showers and thunderstorms are
   anticipated across the TN Valley, Southeast states, and FL as the
   system moves eastward. 

   ...Eastern LA into FL Panhandle/Big Bend...
   Widespread showers and thunderstorms will likely be ongoing at the
   beginning of the period across portions of the Lower MS Valley and
   Mid-South. This activity may impede the moisture return across the
   Southeast states. Current expectation is for modest moisture
   advection (i.e. dewpoints in the low 60s) to occur ahead of the
   surface low (and attendant surface trough) across much of MS and AL
   but the better moisture (i.e. dewpoints in the upper 60s) will
   remain confined to the coastal areas. Strong low-level jet
   accompanying the cyclone will support widespread elevated
   thunderstorms north of the warm front and ahead of the surface low.

   Greater likelihood for surface-based convection is expected along
   the surface trough as it moves across southern MS/AL and FL
   Panhandle. Instability will be limited but strong wind field may
   support occasional updrafts organized enough to produce isolated
   damaging wind gusts and perhaps a tornado or two. Farther northwest
   (in central MS), clearing between the surface trough and cold front
   may result in enough insolation for destabilization and another
   round of thunderstorms. Limited low-level moisture is anticipated
   across the region but cold temperatures aloft (associated with the
   approaching upper low) will still support modest instability.
   Additionally, generally weak low-level wind fields are expected but
   mid-level flow will still be strong enough to support enough bulk
   shear for transient storm organization. Marginal severe
   probabilities were extended back northwestward to account for this
   scenario. Overall severe potential remains too low for anything but
   marginal severe probabilities.

   ..Mosier.. 04/21/2018

   NOTE: THE NEXT DAY 2 OUTLOOK IS SCHEDULED BY 1730Z