U.S. Severe Weather Forecast (Convective Outlook)

Day Three

acus01 kwns 271629 
Storm Prediction Center ac 271627 

Day 1 convective outlook 
National Weather Service Storm Prediction Center Norman OK 
1127 am CDT Thu Apr 27 2017 

Valid 271630z - 281200z 

..there is a slight risk of severe thunderstorms over parts of 
Alabama...GA...and SC... 

..there is a marginal risk of severe thunderstorms over much of the 
eastern United States... 

..there is a marginal risk of severe thunderstorms over parts of 
the Central High plains... 

A few intense storms capable of damaging winds and perhaps hail or a 
tornado will be possible over parts of Georgia and South Carolina. 
Otherwise, isolated severe wind gusts may accompany thunderstorms 
from portions of the Great Lakes region to the southeast states 
today into this evening, and across portions of the central and 
southern Great Plains late this afternoon into this evening. 

An ongoing band of strong thunderstorms continues to occasionally 
Show Low/mid level rotation and indications of severe threat. This 
scenario will likely continue through the afternoon as more storms 
form eastward across central Georgia and eventually into western SC. 
Local VAD profiles and forecast soundings suggest that low/deep 
layer shear is favorable for organized thunderstorms including 
supercells and bowing structures. Continued daytime heating and 
destabilization along the southern fringe of cloud cover across the 
risk area would support an upgrade to slight risk. Locally damaging 
wind gusts are probably the main threat in the strongest cells. 
However, an isolated tornado or two, along with some hail, is 

The latest surface analysis shows a cold front sweeping eastward 
across lower Michigan and western Ohio. Only broken cloud cover ahead of the 
front is helping surface temperatures to climb through the mid 70s, 
resulting in steep low-level lapse rates and marginal instability. 
12z cam solutions are relatively consistent that scattered showers 
and thunderstorm development this afternoon along/ahead of the front 
from eastern Ohio into much of WV and western PA. The storms will 
eventually spread into central PA/Virginia and western Maryland this evening. 
Strongly considered an upgrade to slight over parts of this corridor. 
However, forecast soundings suggest very little cape and mid-level 
lapse rate only in the 6.0 c/km range. It is likely that a few 
fast-moving showers and thunderstorms will pose a risk of 
gusty/damaging wind gusts this afternoon. This region will be 
re-evaluated for an upgrade to slight at 20z. 

A few high-based thunderstorms are expected this afternoon and early 
evening over parts of southeast co, southwest KS, and portions of 
the Texas/OK panhandles. Instability will be quite limited. However, 
steep mid level lapse rates and favorable wind fields suggest some 
risk of hail and gusty winds in the strongest cells. 

.Hart/Mosier.. 04/27/2017 


Mesoscale Discussion

acus11 kwns 271730 
sels mesoscale discussion 
Storm Prediction Center mesoscale discussion 271730 

Mesoscale discussion 0572 
National Weather Service Storm Prediction Center Norman OK 
1230 PM CDT Thu Apr 27 2017 

Areas affected...far southeast Alabama...central Georgia...far western SC 

Concerning...severe potential...watch possible 

Valid 271730z - 271900z 

Probability of watch issuance...60 percent 

Summary...radar trends are being monitored for a potential watch 
across portions of central Georgia. Primary severe threat is expected to 
be damaging wind gusts although hail and brief tornadoes are also 

Discussion...thunderstorms within the ongoing line of storms 
extending from far west-central Georgia into southeast Alabama have continued 
to show sporadic intensification/updraft rotation with several 
storms currently exhibiting low-level rotation. Diurnal heating 
continues to destabilize the downstream environment with 
temperatures across central Georgia now into the low to mid 80s. Recent 
mesoanalysis suggests these surface temperatures amidst dewpoints 
mid 60s are supportive of MLCAPE on the order of 1500 j/kg and 
little to no cin. Recent warm air advection development out ahead of the line 
across west-central Georgia further supports the mesoanalysis estimation 
of little to no cin. Given the supportive downstream environment and 
recent radar trends, a transition to more of a linear cluster 
appears probable with a resultant threat for damaging wind gusts 
across much of central Georgia. However, this transition has not 
completely occurred yet and most of the current radar signatures 
across far southeast Alabama and far west-central Georgia are indicative of a 
few semi-discrete supercells embedded within the line. Trends with 
much of this development thus far is for transient rotation 
supportive of brief tornadoes and gusty winds. 

.Mosier/Hart.. 04/27/2017 

..please see www.Spc.NOAA.Gov for graphic product... 


Latitude...Lon 31438621 32968489 33488368 33948224 33628137 32628187 
32098286 31438621