Dec 20, 2017 1630 UTC Day 1 Convective Outlook
Updated: Wed Dec 20 16:32:16 UTC 2017 (20171220 1630Z Day 1 shapefile | 20171220 1630Z Day 1 KML)
Probabilistic to Categorical Outlook Conversion Table
Categorical Graphic
20171220 1630 UTC Day 1 Outlook Graphic
Day 1 Risk Area (sq. mi.) Area Pop. Some Larger Population Centers in Risk Area
MARGINAL 33,147 5,574,637 Atlanta, GA...Montgomery, AL...Columbus, GA...Macon, GA...Warner Robins, GA...
Probabilistic Tornado Graphic
20171220 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
2 % 11,003 1,068,603 Montgomery, AL...Columbus, GA...Auburn, AL...Phenix City, AL...Prattville, AL...
Probabilistic Damaging Wind Graphic
20171220 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
5 % 33,157 5,574,639 Atlanta, GA...Montgomery, AL...Columbus, GA...Macon, GA...Warner Robins, GA...
Probabilistic Large Hail Graphic
20171220 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
No Risk Areas Forecast
   SPC AC 201632

   Day 1 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   1032 AM CST Wed Dec 20 2017

   Valid 201630Z - 211200Z

   ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS
   OF ALABAMA AND GEORGIA...

   ...SUMMARY...
   A few strong to severe storms remain possible this afternoon mainly
   from southern/eastern Alabama into Georgia.

   ...Deep South...
   Bands of showers and a couple of embedded thunderstorms continue to
   progress generally eastward late this morning across northern GA,
   eastern/southern AL and extreme southeast MS. Within a high
   shear/weak CAPE regime, most of this low-topped convection is
   linearly organized with a few weak/transient mesovortices noted
   since daybreak across parts of AL. This activity is occurring ahead
   of a surface low located near the MS/TN border as of 16Z and
   along/south of a semi-stationary front that extends eastward across
   north-central AL/GA into SC.

   The increasingly open mid-level wave, centered over the Ozarks late
   this morning, will continue steadily eastward toward the coastal
   Carolinas by late this evening. Even with some weakening of this
   mid-level trough, low/mid-tropospheric winds will remain very strong
   while continuing to become largely unidirectional
   (west-southwesterly) over time. Thermodynamic limitations are likely
   to preclude an organized/sustained severe risk. Cloud cover remains
   prevalent within the warm sector and most of the convection/forcing
   for ascent will tend to outrun the more appreciable low-level
   moistening and destabilization. While the overall risk should wane
   by late afternoon/evening, localized wind damage and/or perhaps even
   a brief tornado cannot be ruled out with some of the more sustained
   low-topped convection this afternoon.

   ..Guyer/Dean.. 12/20/2017

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