U.S. Severe Weather Forecast (Convective Outlook)

Day Three

acus01 kwns 301246 
Storm Prediction Center ac 301244 

Day 1 convective outlook 
National Weather Service Storm Prediction Center Norman OK 
0744 am CDT Thursday Oct 30 2014 

Valid 301300z - 311200z 

..there is a marginal risk of severe thunderstorms across central Texas... 

widely scattered thunderstorms are possible today into tonight 
across parts of Texas...Florida...and the Ozarks to middle 
Mississippi River valley. A few strong storms may be possible across 
parts of central Texas late this afternoon and evening. 

An amplifying large-scale pattern will exist over the Continental U.S.. an 
eastward-shifting upper ridge over The Rockies/High Plains will be 
flanked by an amplifying upper trough over the eastern third of the 
Continental U.S....while an additional trough currently centered near 138w 
gradually approaches the Pacific northwest. A cold front will move 
slowly southward across the Florida Peninsula today...while an additional 
cold front sweeps south-southeastward across much of the 
central/Southern Plains and Ozarks/adjacent MS River Valley. 

..central Texas... 
A modestly moist air mass characterized by 50s/some lower 60s f 
surface dewpoints resides across central/south Texas in the wake of the 
prior frontal passage...with 100mb mean mixing ratios of 12.4/14.3 
g/kg observed in 12z observed soundings from del Rio/Corpus Christi 
respectively. A limited degree of northward moisture transition is 
expected to occur in advance of a fast-moving/south-southeastward 
moving cold front across the Central Plains. With the aid of a weak 
surface low and the approaching cold front...a loosely organized 
triple point should materialize across north-central Texas toward peak 
heating. Although large-scale influences will be weak on the 
anticyclonic side of the polar jet...sufficient frontal 
uplift/isentropic ascent in the presence of a modestly unstable 
boundary layer /750-1250 j per kg MLCAPE/ should contribute to at 
least isolated thunderstorm development by late afternoon/early 
evening. This is well-supported by various traditional deterministic 
guidance in addition to virtually all members of the 00z sseo 
including the WRF-NSSL. 

Given the aforementioned buoyancy...strengthening belt of 
north-northwesterly middle-level winds and strong turning with height 
will contribute to 35-40 knots of effective shear...which could support 
some organized storms including a couple of weak/transient 
supercells. As such...marginal-caliber severe probabilities have 
been introduced for mainly a hail risk late this 
afternoon/evening...with the greatest coverage of southward-moving 
thunderstorms expected after dark. 

A cold front will settle slowly southward across the 
northern/central Florida Peninsula through tonight...while an amplifying 
shortwave trough approaches south Georgia/North Florida. Ongoing thunderstorms 
over the eastern Gulf of Mexico may gradually approach the western 
Florida Peninsula today...while other relatively low-topped storms are 
likely to develop in vicinity of the front across the 
north-Central/Northeast peninsula later this afternoon/early 
evening. Although middle-level lapse rates will be weak...steepening 
low-level lapse rates and 60s f surface dewpoints will contribute to 
as much as 750-1000 j/kg MLCAPE this afternoon. While a 
strong/severe thunderstorm cannot be entirely discounted inland 
/such as kdab general vicinity/...current thinking is that severe 
probabilities remain below 5 percent given a marginal thermodynamic 

.Guyer/Bothwell.. 10/30/2014 

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