U.S. Severe Weather Forecast (Convective Outlook)

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Storm Prediction Center ac 200059 


Day 1 convective outlook 
National Weather Service Storm Prediction Center Norman OK 
0759 PM CDT Fri Oct 19 2018 


Valid 200100z - 201200z 


..no severe thunderstorm areas forecast... 


... 
severe storms are not expected over the U.S. Tonight. 


... 
Upper troughing is forecast to continue digging southeastward across 
the Great Lakes and Midwest overnight, with cyclonic flow 
surrounding the trough gradually expanding to encompass essentially 
the entire eastern two-thirds of the country by the end of the 
period. Elsewhere, ridging will persist in the west, though a large 
-- but weak -- upper cyclone will remain just off the California coast 
through the period. 


At the surface, a deepening low will move gradually across western 
Quebec, while the trailing cold front continues to shift southward 
and eastward with time, reaching a position from roughly the 
Appalachians, across the Gulf Coast states, and into northern Mexico 
by the end of the period. 


Showers and thunderstorms continue over portions of the Gulf and 
portion of Mexico, but onshore lightning has been minimal over the 
past hour -- limited to the middle Texas coastal area. A few 
strikes will remain possible overnight across portions the Gulf 
Coast states -- particularly eastern parts of Texas and into western 
Louisiana, and possibly portions of the Texas Big Bend/Davis 
Mountains vicinity. However, most lightning should remain offshore 
over the Gulf, and south of the Rio Grande, through the end of the 
period. A strike or two may also occur across eastern North 
Carolina very late in the period, with possible convection 
developing ahead of the advancing cold front. However, greater 
convective development potential will remain offshore over the Gulf 
Stream. 


.Goss.. 10/20/2018 


$$ 

Mesoscale Discussion


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sels mesoscale discussion 
Storm Prediction Center mesoscale discussion 162228 
ncz000-scz000-170100- 


Mesoscale discussion 1587 
National Weather Service Storm Prediction Center Norman OK 
0528 PM CDT Tue Oct 16 2018 


Areas affected...portions of NC/SC 


Concerning...severe potential...watch unlikely 


Valid 162228z - 170100z 


Probability of watch issuance...5 percent 


Summary...strong/gusty winds may occur on an isolated basis through 
the evening. Watch issuance is unlikely. 


Discussion...glancing influence of large-scale ascent associated 
with an upper-level jet over the mid-Atlantic/northeast coupled with 
modest low-level convergence along a stalled front should support 
isolated to scattered convective development through the evening 
across the southern half of NC and parts of SC. This generally 
east-west oriented front will likely serve as a focus for 
thunderstorms, with a couple attempts at convective initiation noted 
recently near gsp in upstate SC. A meso-low noted on 22z surface 
analysis near Fay may also subtly enhance low-level convergence 
along the front in southern NC. 


Some cloud breaks to the south of the front have contributed to 
temperatures in the low 80s at 2228z. A moist-level airmass is also 
present across the warm sector, with dewpoints generally in the 
upper 60s to lower 70s. Daytime heating and plentiful moisture are 
supporting MLCAPE around 250-1000 j/kg, with poor mid-level lapse 
rates limiting even greater destabilization. 40-50+ kt of 
west-southwesterly mid-level flow is present across much of the 
Carolinas, and a strengthening wind profile with height is 
contributing to around 40-50 kt of effective bulk shear. Mid-level 
rotation within thunderstorm updrafts will likely occur given this 
degree of shear, and a couple transient supercells cannot be ruled 
out. A small line segment or thunderstorm cluster will probably 
consolidate along the front as it moves eastward through the 
evening. 


Even with nocturnal cooling commencing soon, already steepened 
low-level lapse rates should encourage efficient momentum Transfer 
of convective downdrafts to the surface. Isolated strong/gusty winds 
primarily capable of tree damage appear to be the main severe 
threat, but very isolated hail may also occur. Regardless, the 
thermodynamic environment will remain quite marginal, and watch 
issuance is unlikely at this time. 


.Gleason/Edwards.. 10/16/2018 


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


Attention...WFO...mhx...rah...ilm...cae...gsp... 


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