U.S. Severe Weather Forecast (Convective Outlook)

Day Three

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Storm Prediction Center ac 151602 

Day 1 convective outlook 
National Weather Service Storm Prediction Center Norman OK 
1002 am CST Thu Nov 15 2018 

Valid 151630z - 161200z 

..there is a slight risk of severe thunderstorms this afternoon 
over far eastern North Carolina... 

Isolated damaging gusts and a tornado or two may occur from late 
this morning through afternoon over portions of near-coastal eastern 
North Carolina. 

..eastern NC... 
Only minor changes have been made to the ongoing forecast. Latest 
surface analysis shows a deepening surface low just off the NC coast 
near Cape Fear, with a warm front extending eastward out to sea. 
Several significant supercells are noted on radar along this 
boundary. Observational trends suggest that destabilization over 
eastern NC is occurring slightly slower than anticipated due to this 
widespread convection. The back edge of the convection is also 
progressing eastward faster than guidance. Present indications are 
that the Outer Banks and coastal counties of far eastern NC may be 
briefly in the warm sector this afternoon. If this occurs, very 
strong low-level shear will pose a threat of damaging wind gusts and 
perhaps a tornado in any persistent convective core. However, the 
area and time period of potential is decreasing. 

.Hart/Kerr.. 11/15/2018 


Mesoscale Discussion

acus11 kwns 151700 
sels mesoscale discussion 
Storm Prediction Center mesoscale discussion 151659 

Mesoscale discussion 1649 
National Weather Service Storm Prediction Center Norman OK 
1059 am CST Thu Nov 15 2018 

Areas affected...far eastern North Carolina...Outer Banks vicinity 

Concerning...severe potential...watch unlikely 

Valid 151659z - 151930z 

Probability of watch issuance...20 percent 

Summary...some risk for thunderstorms accompanied by potentially 
damaging wind gusts, or perhaps a tornado, may develop across parts 
of far eastern North Carolina and the Outer Banks area through 3-5 
PM EST. Due to the isolated, somewhat marginal, nature of this 
threat, it is not clear that a severe weather watch will be needed, 
but trends will be monitored. 

Discussion...an area of ongoing convection and embedded thunderstorm 
activity now east of the North Carolina coast appears supported by 
warm advection and convergence along the surface warm front, and a 
southward trailing pre-cold frontal low-level confluence zone. This 
also appears to be occurring beneath strongest difluence aloft, 
which is forecast to continue developing north/northeastward through 
early/mid afternoon. As it does, strongest boundary-layer based 
thunderstorms appear likely to pass to the south/east of the Outer 
Banks vicinity. 

However, increasing surface pressure falls are now underway across 
much of eastern North Carolina into Virginia, and a developing area 
of low pressure along the surface frontal zone appears likely to 
migrate inland near/east of Wilmington, before continuing across the 
coastal plain toward the Hampton Roads area through 20-22z. As this 
occurs, backing and strengthening near surface flow may allow for an 
influx of seasonably high boundary layer moisture content across the 
Outer Banks area and nearby coastal areas during the next few hours. 
Despite generally weak to modest low/mid-level lapse rates, 
forecast soundings suggest that this may be sufficient to contribute 
to mixed-layer cape on the order of 500-1000 j/kg. 

Given this destabilization, there may be a window of opportunity for 
isolated renewed thunderstorm development across far eastern North 
Carolina and the Outer Banks. Although it appears that the 
clockwise curvature in the low-level hodographs may decrease by this 
time, momentum/shear beneath 50+ kt southerly 850 flow will still 
provide some potential for strong wind gusts, if not an isolated 
tornado or two. 

.Kerr/Hart.. 11/15/2018 

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


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