U.S. Severe Weather Forecast (Convective Outlook)

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Storm Prediction Center ac 311957 


Day 1 convective outlook 
National Weather Service Storm Prediction Center Norman OK 
0257 PM CDT Friday Oct 31 2014 


Valid 312000z - 011200z 


..no severe thunderstorm areas forecast... 


... 
severe thunderstorms are not expected today or tonight. 


..srn Lake Michigan and northwestern ind/far southwestern lower Michigan... 
The potential for lightning strikes should continue to diminish this 
afternoon and be confined to mainly inland locations to the south-southeast of 
Southern Lake Michigan. The strong impulse that has aided convective 
development through early afternoon will continue to shift away from 
this discussion area through the lower Ohio Valley...diminishing the 
thunderstorm potential from north to south. 


..S Texas... 
General thunderstorm area has been removed from south Texas as northerly flow in the 
lowest 3-4 km above ground level continues to usher in drier...cooler and more 
stable air. 


... 
No changes needed to the rest of the outlook. 


.Peters.. 10/31/2014 


Previous discussion... /issued 1100 am CDT Friday Oct 31 2014/ 


... 
The Rockies upper ridge will be flanked by a trough over the eastern 
third of the U.S. And a trough over the eastern Pacific/U.S. West 
Coast. As this eastern Pacific trough moves onshore...the upper 
ridge will slowly migrate east over the plains by 12z/Sat. A mean 
trough will be maintained across the eastern u... a couple of 
embedded vorticity maxima leading to a deepening of this system 
through Saturday morning. 


While cold/dry surface high pressure will dominate much of the central 
Continental U.S....areas of thunderstorms will be possible in a few locations. 
Across parts of California...height falls/cooling temperatures aloft 
accompanying the eastward progressing trough and moist...orographic 
ascent should allow for isolated thunderstorms this afternoon into 
the overnight hours. Additional thunderstorms will be possible in 
the vicinity of the southern rockies/Four Corners region as a lead 
shortwave impulse ejects eastward ahead of the main Pacific trough. 
Elsewhere...a Few Lake effect thunderstorms will be possible over 
Southern Lake Michigan an adjacent areas just downstream as a strong vorticity 
maximum pivots southeastward over this region. The resulting strong height falls 
and cooling temperatures/steepening lapse rates atop favorable 
trajectories over the relatively warmer lake waters may produce a 
few lightning strikes in addition to some sleet/snow. Later today 
into tonight...additional isolated storms may occur over parts of 
the southern Appalachians as a secondary shortwave impulse rotates 
through the base of the mean trough. 

Mesoscale Discussion


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Storm Prediction Center mesoscale discussion 151720 
paz000-mdz000-151945- 


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 
expected. 


.Jewell/corfidi.. 10/15/2014 


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


Attention...WFO...phi...ctp...lwx... 


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