Jan 20, 2017 0830 UTC Day 3 Severe Thunderstorm Outlook
Updated: Fri Jan 20 06:18:45 UTC 2017 (20170120 0830Z Day 3 shapefile | 20170120 0830Z Day 3 KML)
Probabilistic to Categorical Outlook Conversion Table
Categorical Graphic
0830 UTC Day 3 Outlook Graphic
Day 3 Risk Area (sq. mi.) Area Pop. Some Larger Population Centers in Risk Area
ENHANCED 50,981 10,715,640 Jacksonville, FL...Tampa, FL...St. Petersburg, FL...Orlando, FL...Tallahassee, FL...
SLIGHT 85,233 13,733,499 Miami, FL...Hialeah, FL...Montgomery, AL...Columbus, GA...Fort Lauderdale, FL...
MARGINAL 66,142 12,680,672 Atlanta, GA...Raleigh, NC...Birmingham, AL...Fayetteville, NC...Columbia, SC...
Probabilistic Graphic
20170120 0830 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 3 Prob. Risk Area (sq. mi.) Area Pop. Some Larger Population Centers in Risk Area
30 % 51,391 10,744,252 Jacksonville, FL...Tampa, FL...St. Petersburg, FL...Tallahassee, FL...Savannah, GA...
15 % 84,046 13,673,740 Miami, FL...Hialeah, FL...Orlando, FL...Montgomery, AL...Columbus, GA...
5 % 66,116 12,661,693 Atlanta, GA...Raleigh, NC...Birmingham, AL...Fayetteville, NC...Columbia, SC...
   SPC AC 200618

   Day 3 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   1218 AM CST Fri Jan 20 2017

   Valid 221200Z - 231200Z

   ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
   SOUTHERN GA AND NORTHERN/CENTRAL FL...

   ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM THE FL
   PANHANDLE TO COASTAL NC...

   ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM THE CENTRAL
   GULF STATES TO EASTERN NC...

   ...SUMMARY...
   Severe thunderstorms, with damaging winds and perhaps some hail, are
   expected across much of the southeastern US Sunday.

   ...Southeast...

   Short-range models begin to diverge a bit by Sunday afternoon as the
   NAM is considerably faster and farther north with the upper low
   center than the GFS/UKMET/Canadian which advance the low into
   northern AL.  The NAM would suggest a faster and more advanced
   squall line into the southeastern states early in the period as
   large-scale forcing is substantially east of the other models at
   22/12z.  Even so, quality boundary-layer air mass resides over the
   Gulf basin and this should advance inland easily ahead of stronger
   forcing and expected convection.

   Severe thunderstorms, in the form of a squall line, may be ongoing
   at 22/12z...a continuation of late day2 convection that will be
   supported by a strong progressive mid-level speed max on the order
   of 110kt.  In response to this feature, LLJ will increase over the
   northeastern Gulf basin into coastal Carolinas.  Associated warm
   advection will aid convection as it advances through a well-defined
   ascent corridor.  Current thinking is a squall line should migrate
   across the Gulf states, eventually progressing across the FL
   peninsula as flow strengthens from the west.  Damaging winds and
   perhaps some hail and possibly a few tornadoes can be expected with
   this activity.

   ..Darrow.. 01/20/2017

   NOTE: THE NEXT DAY 3 OUTLOOK IS SCHEDULED BY 0830Z