U.S. Severe Weather Forecast (Convective Outlook)

Day Three

acus01 kwns 211930 
Storm Prediction Center ac 211929 

Day 1 convective outlook 
National Weather Service Storm Prediction Center Norman OK 
0229 PM CDT Tuesday Oct 21 2014 

Valid 212000z - 221200z 

..no severe thunderstorm areas forecast... 

isolated to widely scattered thunderstorms will continue into the 
evening over parts of The Rockies...southwest and south 
Texas...South Florida...as well as southern New England and 
middle-Atlantic region. 


Current forecast remains on track with only minor adjustments made 
with this update. 

.Dial.. 10/21/2014 

Previous discussion... /issued 1123 am CDT Tuesday Oct 21 2014/ 

An initial shortwave trough will eject northeastward from the middle Atlantic 
coast to southeast New England coast and weaken this afternoon...as an 
upstream closed low forms over the upper Ohio Valley/central 
Appalachians. This closed low will then drift eastward to the middle 
Atlantic region by early Wednesday. Associated surface cyclogenesis 
is expected near and just off the middle Atlantic coast later today 
into tonight. Though low-level moisture will be limited over land 
in this pattern...cooling temperatures aloft and relatively steep 
lapse rates will contribute to weak buoyancy and the risk for 
isolated thunderstorms in the zone of ascent preceding the 
developing midlevel low. 

Elsewhere...a pronounced shortwave trough will progress east-northeastward from 
Idaho to the northern High Plains and weaken gradually by late tonight. 
Steep midlevel lapse rates and modest low-midlevel moisture will 
support weak buoyancy and a continued risk for widely-scattered 
thunderstorms into parts of the northern rockies this afternoon. A few 
thunderstorms will again be possible from SW Texas into nm within the 
lingering moisture plume associated with a weakening southern stream 
trough. A few thunderstorms are also expected within the northern fringe 
of the tropical air mass across S Texas and S Florida today. 

Mesoscale Discussion

acus11 kwns 151721 
sels mesoscale discussion 
Storm Prediction Center mesoscale discussion 151720 

Mesoscale discussion 1899 
National Weather Service Storm Prediction Center Norman OK 
1220 PM CDT Wednesday Oct 15 2014 

Areas affected...central Maryland into southeastern PA 

Concerning...severe potential...watch unlikely 

Valid 151720z - 151945z 

Probability of watch issuance...20 percent 

Summary...an isolated strong wind gust or brief/weak tornado cannot 
be ruled out with storms as they develop northward from Maryland into southeastern PA. 

Discussion...an isolated strong cell with substantial vertical 
development continues to propagate northward along a north-S oriented boundary 
which extends into PA and links with an existing front across eastern PA 
which currently separates the more moist/unstable air to the southeast. 

This particular storm has had a persistent and broad circulation 
with it...but nothing particularly strong or tight probably due to 
weak low-level buoyancy/acceleration. While deep-layer flow is 
strong above the ground...most of the shear is relegated to the 
near-surface layer and other cells away from the outflow boundary 
have shown little if any shear. Therefore...any wind/tornados threat is 
expected to be brief...short-lived and isolated...and a watch is not 

.Jewell/corfidi.. 10/15/2014 

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


Latitude...Lon 39157664 39007677 38987688 39067699 39267696 39617690 
40007679 40347640 40457615 40407593 40137594 39617620