Jan 27, 2021 1300 UTC Day 1 Convective Outlook
Updated: Wed Jan 27 12:52:22 UTC 2021 (20210127 1300Z Day 1 shapefile | 20210127 1300Z Day 1 KML)
Probabilistic to Categorical Outlook Conversion Table
Categorical Graphic
20210127 1300 UTC Day 1 Outlook Graphic
Day 1 Risk Area (sq. mi.) Area Pop. Some Larger Population Centers in Risk Area
MARGINAL 28,657 1,934,937 Jacksonville, FL...Tallahassee, FL...Albany, GA...Valdosta, GA...Hinesville, GA...
Probabilistic Tornado Graphic
20210127 1300 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 % 24,324 1,461,693 Tallahassee, FL...Albany, GA...Valdosta, GA...Hinesville, GA...Thomasville, GA...
Probabilistic Damaging Wind Graphic
20210127 1300 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 % 28,764 1,944,422 Jacksonville, FL...Tallahassee, FL...Albany, GA...Valdosta, GA...Hinesville, GA...
Probabilistic Large Hail Graphic
20210127 1300 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 271252

   Day 1 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   0652 AM CST Wed Jan 27 2021

   Valid 271300Z - 281200Z


   Thunderstorms will pose a marginal severe-weather threat today
   across southern Georgia and extreme northern Florida.

   In mid/upper levels, a high-amplitude trough will remain just
   offshore from the Pacific Coast through the period, as one
   accompanying cyclone now offshore from OR ejects northeast and is
   replaced by another developing into essentially the same area by 12Z
   tomorrow.  Associated cold air aloft will contribute to marginal
   instability for thunder near portions of the CA Coast.  Downstream,
   a strong shortwave trough was apparent in moisture-channel imagery
   over portions of KS/OK.  This perturbation will deamplify somewhat
   -- but still remain well-defined -- as it accelerates eastward
   across the Mid-South to the Tennessee Valley today.  By the end of
   the period, the trough should reach the eastern Carolinas. 

   As that occurs, a weak surface low -- analyzed at 11Z near MAI --
   should ripple east-northeastward along what is now a quasistationary
   frontal zone extending from southeastern LA across southern GA.  The
   low should move offshore around 00Z and merge with another cyclone
   developing in the cool sector over SC.  The combined cyclone should
   deepen substantially late tonight as it crosses Atlantic waters
   progressively farther offshore from GA and the Carolinas.  Behind
   the low this evening, the boundary should accelerate southeastward
   across the outlook area as a strong cold front, reaching south FL by

   ...Southern GA/northern FL, eastern FL Panhandle...
   Widely scattered to scattered thunderstorms are expected to move
   eastward across the area, mainly ahead of the surface front.  A few
   embedded/transient supercells are possible.  A marginal damaging-
   wind/tornado threat exists through late afternoon.  

   This regime will be bracketed on the north by relatively stable air
   north of the frontal zone.  The shortwave trough and related
   DCVA/cooling aloft will pass well north of the area, minimizing
   direct upper support and keeping deep-layer lapse rates weak.  This
   will keep MLCAPE around 500 J/kg or less in most areas.  Still,
   associated tightening of height gradients will strengthen deep/speed
   shear over the area, contributing to effective-shear magnitudes of
   45-55 kt, despite veered near-surface winds.  This flow geometry
   will limit low-level shear and lift, though:
   1.  Weak MLCINH should enable convective initiation with available
   frontal and near-cyclone lift anyway, and 
   2.  Forecast soundings do indicate enough hodograph curvature to
   support pockets of marginal (around 150 J/kg) effective SRH,
   especially midday over parts of the eastern FL Panhandle and
   southern GA.  The southwesterly surface flow also will advect
   better-modified Gulf air with greater moisture across the area,
   supporting greater eastward longevity of convection. 

   Weaker boundary-layer buoyancy and deep-layer lift are forecast with
   southward extent and time this evening over northern FL, reducing
   the severe potential.

   ..Edwards/Gleason.. 01/27/2021