U.S. Severe Weather Forecast (Convective Outlook)

Day Three

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Storm Prediction Center ac 060544 

Day 1 convective outlook 
National Weather Service Storm Prediction Center Norman OK 
1244 am CDT Monday Jul 06 2015 

Valid 061200z - 071200z 

..there is a slight risk of severe thunderstorms across portions of the 
Midwest/south-Central Plains... 

..there is a marginal risk of severe thunderstorms from the southern High Plains 
to the upper Great Lakes... 

..there is a marginal risk of severe thunderstorms across the Middle-Atlantic 

..there is a marginal risk of severe thunderstorms across the Florida 
Peninsula/southeast states... 

Strong to severe thunderstorms will be possible mainly this 
afternoon and evening in parts of the Midwest and south-Central 
Plains in addition to areas including the Florida Peninsula and 
Middle-Atlantic States. 

A semi-progressive large-scale pattern will exist particularly over 
the northern half of the Continental U.S....highlighted by an amplifying upper 
trough over northern Ontario and the adjacent upper Midwest/upper 
Great Lakes. An extensive southeastward-moving cold front across the 
upper Midwest/upper Great Lakes...MO valley...and south-Central 
Plains will be a general focus for thunderstorm development 
particularly into this afternoon/evening. 

..IA/upper MS River Valley... 
Primary larger-scale forcing for ascent will overspread the upper MS 
River Valley/upper Great Lakes today...while a cold front will 
spread southeastward across the region. While a moist/potentially 
unstable air mass would otherwise continue to advect into the region 
from the southwest...it seems likely that extensive overnight/early 
day convection and related outflow/cloud cover will be prevalent 
within the pre-frontal warm sector...particularly 
north-northeastward into WI/Upper Michigan where the opportunity for 
consequential destabilization should remain limited. That 
said...storms could redevelop near the front this afternoon with 
some potential for wind/hail mainly across Iowa into southern WI 
and/or possibly near remnant outflow a bit farther east into areas 
such as northern Illinois/lower Michigan. 

..lower MO valley/south-Central Plains/Ozarks... 
Steepening low-level lapse rates and frontal uplift will lead to at 
least widely scattered thunderstorms late this afternoon/early 
evening near the southeastward-moving front across the MO 
valley/south-Central Plains including a corridor across northern MO 
to eastern/southern Kansas...northern OK...and the Texas Panhandle/eastern 
nm. While vertical shear will be weak...a hot/moist pre-frontal 
boundary layer will support the potential for episodic downbursts 
capable of localized wind damage and possibly some marginally severe 

Elsewhere...a few other strong/potentially severe pulse-type 
thunderstorms capable of downbursts with localized wind damage may 
also develop within a very unstable air mass across the 
Ozarks/middle MS River Valley this afternoon/early evening. 

..mid-Atlantic states... 
An upper low will continue to move/accelerate northeastward and 
generally tend to weaken over the Appalachians prior to eventually 
phasing with northern stream westerlies early Tuesday. A modestly 
enhanced south-southwesterly low/mid-tropospheric wind field should 
accompany the eastern periphery of the aforementioned upper 
low...with a warm front otherwise spreading northward across the 
region. Middle-level lapse rates will be very weak...but sufficient 
cloud breaks/heating may allow a few strong storms to develop this 
afternoon. A couple of downbursts and/or weak/transient supercells 
will be possible pending sufficient destabilization...but even 
so...the overall severe potential should remain marginal. 

..FL/coastal southeast states... 
Although portions of the region experienced extensive convection on 
Sunday...thermodynamic conditions should be at least marginally 
supportive of some stronger storms this afternoon with downburst 
potential across the Florida Peninsula and possibly adjacent areas 
including parts of Alabama/GA/coastal SC. 

.Guyer/Gleason.. 07/06/2015 

Mesoscale Discussion

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sels mesoscale discussion 
Storm Prediction Center mesoscale discussion 060601 

Mesoscale discussion 1313 
National Weather Service Storm Prediction Center Norman OK 
0101 am CDT Monday Jul 06 2015 

Areas affected...southeastern South Dakota / northwestern Iowa / extreme southwestern Minnesota 

Concerning...Severe Thunderstorm Watch 393... 

Valid 060601z - 060630z 

The severe weather threat for Severe Thunderstorm Watch 393 

Summary...the wind damage threat may extend beyond the eastern bound of 
severe watch 393. 

Discussion...kfsd radar showed rapid tornadogenesis with a 
mesovortex around 0520z /per 50 knots rotational velocity and cirrocumulus 
minimum/ as a gust front from leading convection over southwestern Minnesota/southeastern 
South Dakota intersected the bowing segment. The overall convective 
organization is partly associated with a well-developed mesoscale convective vortex in the 
trailing stratiform region near the Keya Paha County Nebraska/Tripp 
County South Dakota border. As the cold pool continues to move east/southeastward across 
the tri-state area...an appreciably moist boundary layer /surface 
dewpoints in the lower 70s/ amidst a veering flow regime will 
support the notion for additional strong to severe storm activity. 
The primary wind damage risk will likely be associated with the 
bowing segment and any subsequent mesovortices that manage to 
develop. As a result of this expected risk...a watch 
extension-in-area or a new watch may be needed to address the 
evolving threat. 

.Smith.. 07/06/2015 

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


Latitude...Lon 43519714 43709622 43819534 43349498 42879548 42719625 
42769726 43519714