U.S. Severe Weather Forecast (Convective Outlook)

Day Three

acus01 kwns 151952 
Storm Prediction Center ac 151950 

Day 1 convective outlook 
National Weather Service Storm Prediction Center Norman OK 
0250 PM CDT Mon Oct 15 2018 

Valid 152000z - 161200z 

..there is a marginal risk of severe thunderstorms across portions 
of the middle-Atlantic region and into southern New England... 

Isolated strong wind gusts yielding tree damage remain possible 
across the mid-Atlantic states to southern New England between about 
8 PM to midnight EDT. 

As a cold front continues to cross the eastern U.S. Today, a frontal 
convective band -- now developing across parts of central and 
western PA/western WV -- is forecast to strengthen a bit as it 
crosses the Appalachians and encounters a modestly more-unstable 
airmass -- particularly near the mid-Atlantic and southern New 
England coasts. Very strong flow aloft observed continues to 
suggest potential for isolated stronger wind gusts, but overall risk 
-- as per prior forecasts -- should remain limited in coverage and 

.Goss.. 10/15/2018 

Previous discussion... /issued 1120 am CDT Mon Oct 15 2018/ 

..mid-Atlantic states to southern New England... 
Have made a small expansion to the southwest of the marginal risk 
based on morning cams, but otherwise previous forecast reasoning 
remains valid. 

An amplified shortwave trough over the upper Great Lakes will move 
east towards the lower Saint Lawrence valley through tonight. A 
surface cyclone near the Ontario/Quebec border will deepen as it 
shifts east, with an attendant occluded cold front pushing east 
across the northern/central Appalachians this afternoon and towards 
the northeast coast this evening. Widespread cloud coverage will 
limit boundary-layer heating north of Maryland/de, but a plume of mid 60s 
boundary-layer dew points should advect northeast into southern New 
England ahead of the front. The lack of greater heating along with 
weak mid-level lapse rates should yield only meager buoyancy with 
MLCAPE remaining below 500 j/kg. However, low-level ascent along the 
front will contribute to the development of a narrow band of 
low-topped convection with some embedded lightning. With 
strengthening of low/mid-level southwesterlies (55-65 kt at 700 mb), 
downward momentum transport in the weak convection could support 
isolated strong gusts that yield tree damage during the late 


Mesoscale Discussion

acus11 kwns 150430 
sels mesoscale discussion 
Storm Prediction Center mesoscale discussion 150430 

Mesoscale discussion 1585 
National Weather Service Storm Prediction Center Norman OK 
1130 PM CDT sun Oct 14 2018 

Areas affected...northeast Texas 

Concerning...Severe Thunderstorm Watch 415... 

Valid 150430z - 150500z 

The severe weather threat for Severe Thunderstorm Watch 415 

Summary...although locally strong winds and small hail cannot be 
ruled out with the remaining storms advancing across the small valid 
portion of ww 415, this watch should be allowed to expire as 
scheduled at 05z as the overall convective trends weaken. 

Discussion...trends in radar imagery and lightning data with the 
convection across northeast Texas indicated a substantial decrease in 
intensity and coverage, respectively. This is likely due to the 
increasing influence of strengthening surface-based inhibition, and 
these trends will continue to limit the severe-weather threat into 
the overnight. 

.Peters.. 10/15/2018 

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


Latitude...Lon 32829530 33219461 32399467 32169496 32129536 32829530