U.S. Severe Weather Forecast (Convective Outlook)

Day Three

acus01 kwns 130501 
Storm Prediction Center ac 130500 

Day 1 convective outlook 
National Weather Service Storm Prediction Center Norman OK 
1200 am CDT Tuesday Oct 13 2015 

Valid 131200z - 141200z 

..no severe thunderstorm areas forecast... 

areas of isolated to widely scattered...generally weak thunderstorm 
activity are possible today...mainly near the Gulf Coast...and along 
the Atlantic Seaboard. 

Within the middle-latitude westerlies...broad upper ridging across the 
eastern Pacific into the Lee of the U.S. Rockies...and broad upper 
troughing across the Mississippi Valley through the Atlantic 
Seaboard...will be maintained through this period. The most 
prominent embedded short wave trough...now crossing the Great Lakes 
and Ohio Valley region...is forecast to accelerate through the 
northeastern U.S. Today...with the leading edge of associated 
low-level cooling and/or drying advancing across much of the 
Atlantic coast...and into the Gulf Coast/lower Rio Grande 
Valley...by 12z Wednesday. 

A narrow corridor of destabilization ahead of this latter feature 
may provide the focus for thunderstorm development...but this is 
generally expected to remain weak...with weak low-level forcing for 
ascent also contributing to rather sparse potential coverage/low 
probability of occurrence. Moisture return could contribute to 
sizable cape across parts of the lower Rio Grande Valley. 
However...primary forcing for thunderstorm development may be within 
the low-level upslope flow into the higher terrain to the South/West 
of the river...with deep layer flow fields/shear tending to keep 
activity on the Mexican side of the river. 

.Kerr.. 10/13/2015 


Mesoscale Discussion

acus11 kwns 122049 
sels mesoscale discussion 
Storm Prediction Center mesoscale discussion 122049 

Mesoscale discussion 1851 
National Weather Service Storm Prediction Center Norman OK 
0349 PM CDT Monday Oct 12 2015 

Areas affected...far southern Illinois...far southern ind...western Kentucky...western Tennessee...far southeast 
MO...far NE Arkansas 

Concerning...severe potential...watch unlikely 

Valid 122049z - 122315z 

Probability of watch issuance...20 percent 

Summary...a marginal severe threat may develop late this afternoon 
into early evening across parts of the middle MS valley and lower Ohio 
Valley. A few strong wind gusts will be possible as cells gradually 
intensify over the next few hours. Ww issuance is not expected due 
to the marginal nature of the threat. 

Discussion...latest surface analysis shows a cold front located from 
scntrl ind southwestward into southeast MO with a corridor of low-level moisture 
extending northeastward into the lower Ohio Valley just ahead of the front. 
Scattered thunderstorms have developed this afternoon near and just 
ahead of the front. The airmass ahead of the front is weakly 
unstable but surface dewpoints are in the upper 50s and lower 60s f. 
This airmass should become a bit more unstable over the next few 
hours. In addition...the Paducah WSR-88D vwp shows moderate 
deep-layer shear with some veering of winds with height from 0 to 2 
km above ground level. As thunderstorms continue to gradually organize into a line 
over the next couple of hours...the environment may support a 
marginal wind damage threat. 

.Broyles/Hart.. 10/12/2015 

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


Latitude...Lon 35588865 35238909 35118952 35379005 35869011 36748931 
37718803 38108739 38248701 38148640 37988616 37588608 
36928672 36328767 35588865