U.S. Severe Weather Forecast (Convective Outlook)

Day Three

acus01 kwns 241956 
Storm Prediction Center ac 241955 

Day 1 convective outlook 
National Weather Service Storm Prediction Center Norman OK 
0155 PM CST Monday Nov 24 2014 

Valid 242000z - 251200z 

..there is a marginal risk of severe thunderstorms from the Florida Panhandle through 
southern Georgia into the eastern Carolinas... 

A marginal threat for isolated strong wind gusts will persist next 
few hours from the Florida Panhandle to the eastern Carolinas. 


No significant changes to ongoing forecast. Convection including a 
few thunderstorms continue developing generally along and in wake of 
a weakening outflow boundary from the Florida Panhandle into the eastern 
Carolinas. Activity is embedded within strong southwesterly unidirectional 
deep layer winds...but cape and lapse rates are very marginal...and 
both observed and forecast soundings indicate an inversion around 
600 mb. These factors should remain detrimental to the development 
of more robust updrafts and serve as a limiting factor for a greater 
severe threat. Nevertheless a few of the stronger storms could 
produce isolated strong to damaging wind gusts particularly in 
vicinity of the boundary over northern Florida/southern Georgia. 

.Dial.. 11/24/2014 

Previous discussion... /issued 1023 am CST Monday Nov 24 2014/ 

A series of embedded speed maxima will rotate through the 
large-scale trough that is now established over most of the Continental U.S.. 
the strongest jet streak will translate northeastward from the upper Ohio 
Valley to the Saint Lawrence valley through the afternoon...while a 
separate wave moves east-southeastward from the southern rockies to the Southern Plains. 
The primary surface cyclone has already developed north-northeastward to the north of 
Lake Huron...while the trailing cold front moves eastward across the Ohio 
Valley. The southern extent of this front will move much slower to the east 
across Alabama/GA/srn Appalachians...in response to the approach of the 
upstream trough over the Southern Plains. 

..upper Ohio Valley to the lower Great Lakes today... 
Ascent in the left exit region of the primary upper jet streak...in 
conjunction with low-level lift along a surface cold front...is 
supporting a band of low-topped convection across central/north central 
Ohio. The depth and vigor of this convection has been diminishing 
over the past 1-2 hours...and the risk for additional lightning has 
decreased. Still...downward momentum Transfer with shallow 
convection could support isolated strong gusts through this 
afternoon across NE Ohio...northwest PA...and western New York. 

..NE Gulf Coast to the southeast Atlantic coast through tonight... 
A band of pre-frontal convection is ongoing along the gradient in 
low-level moisture/buoyancy from the central Florida Panhandle to southeast Georgia. 
Though rich low-level moisture is present to the east-southeast of the 
convection /boundary layer dewpoints in the low 70s/...12z soundings 
revealed poor lapse rate profiles from the surface to almost 500 mb. 
Deep-layer vertical shear and buoyancy will be sufficient for some 
organized cells/line segments within the band. However...limited 
surface heating...poor lapse rate profiles aloft...and a tendency 
for weakening low-level shear with time should keep the damaging 
wind risk in the marginal category. 

Mesoscale Discussion

acus11 kwns 241517 
sels mesoscale discussion 
Storm Prediction Center mesoscale discussion 241517 

Mesoscale discussion 1951 
National Weather Service Storm Prediction Center Norman OK 
0917 am CST Monday Nov 24 2014 

Areas affected...portions of central and eastern Ohio...western 
Pennsylvania...northern West Virginia Panhandle...southwest New York 

Concerning...severe potential...watch unlikely 

Valid 241517z - 241745z 

Probability of watch issuance...5 percent 

Summary...low-topped convection...with little to no lightning...will 
cross portions of the lower Great Lakes and Ohio Valley region into 
the afternoon hours and will be capable of producing gusty winds as 
it spreads NE. A ww will not be needed. 

Discussion...quasi-linear convective segments continue spreading NE 
within broadly confluent flow preceding a front analyzed from 
central lower Michigan to northwestern Kentucky. As the second vorticity maximum in a series of 
three training midlevel perturbations lifts into southwestern 
Ontario...stronger ascent and the aforementioned surface features will 
progress rapidly northeastward...with convection spreading NE into the 
afternoon -- reaching Columbus and Cleveland in the next hour or so. 
However...as stronger middle-level DCVA spreads NE of the international 
border...convection will continue to trend toward a low-topped 
regime. This is evidenced by the recent...rapid decrease in 
lightning coverage in northwestern/N-cntrl Ohio...along with a notable 
subsidence inversion sampled by the 12z Wilmington Ohio radiosonde observation just 
below the 700-mb level. The presence of pre-frontal dewpoints in the 
lower 50s will support a dearth of buoyancy -- MLCAPE of 100-300 
j/kg with el temperatures warmer than -20c. However...very strong 
low-level flow -- east.G. 60-70 knots swlys sampled by the Wilmington and 
Cleveland Ohio vwps at 1 km above ground level will enhance convective momentum 
transport with the potential for strong to perhaps locally 
marginally severe wind gusts into the afternoon. The paucity of 
buoyancy/dearth of moisture...and lagging stronger 
frontal/baroclinic circulations...should preclude a greater severe-thunderstorm 
risk from occurring. 

.Cohen/Thompson.. 11/24/2014 

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


Latitude...Lon 41298251 41618170 41978056 42407931 40598014 39728192 
39588338 40298333 41298251