U.S. Severe Weather Forecast (Convective Outlook)

Day Three

acus01 kwns 241630 
Storm Prediction Center ac 241628 

Day 1 convective outlook 
National Weather Service Storm Prediction Center Norman OK 
1128 am CDT sun Jul 24 2016 

Valid 241630z - 251200z 

..there is a slight risk of severe thunderstorms over northestern Illinois/extreme southeastern 
WI/southwestern lower Michigan and northern Indiana... 

..there is a slight risk of severe thunderstorms over eastern Colorado... 

..There is a marginal risk of severe thunderstorms from the Great Lakes into the 

..there is a marginal risk of severe thunderstorms over central/southern Florida... 

severe thunderstorms capable of producing damaging wind gusts and 
large hail will be possible over parts of eastern Colorado...and 
over parts of northeast Illinois...extreme southeast 
Wisconsin...southwest lower Michigan and northern Indiana...mainly 
during the later afternoon and evening. Isolated severe storms will 
be possible across the Great Lakes and Midwest regions...and over 
the central and southern Florida Peninsula. 

..northeast Illinois/extreme southeastern WI/southwestern lower Michigan and northern Indiana... 
Ongoing storms over lower Michigan have generated a composite outflow 
boundary extending from northwestern Ohio and northern Indiana into Southern Lake Michigan. 
Widespread cloud cover to the north of this boundary is expected to 
limit diabatic heating and strengthen the thermal gradient along the 
composite warm front/outflow boundary. To the S/SW of this 
boundary...strong heating and diurnal destabilization will occur 
within an environment characterized by ample moisture with surface 
dew points in the upper 70s...resulting in MLCAPE of 2500-4000 j/kg 
likely this afternoon. 

Although large scale ascent associated with the upper trough 
translating eastward over northern Minnesota and Lake Superior will remain north of 
this area...weak low-level convergence along an approaching cold 
front...potentially enhanced near a projected outflow boundary/front 
intersection...may be sufficient to initiate widely scattered 
thunderstorms over this region during the late afternoon and evening 
hours. Modest vertical shear will promote a few organized multicell 
clusters with potential for damaging wind gusts and large hail to 

..ern Colorado... 
Moist upslope low-level flow will become better established across 
the area this afternoon as strong heating occurs over the mountains 
and plains...with surface dew points remaining in the 50s especially 
across the plains. Steep middle-level lapse rates will contribute to 
moderate instability with MLCAPE of 1000-2000 j/kg developing this 
afternoon. Model consensus indicates storms will develop near the 
Front Range by middle-afternoon with activity spreading eastward across the 
plains through the evening. Strong directional shear with height 
will enhance storm organization with more intense storms capable of 
producing large hail and strong wind gusts. 

..central/southern Florida... 
As an upper low moves westward across the southern peninsula...thunderstorms 
are expected to continue developing over the central/southern parts of 
the state. Relatively cool middle-level temperatures are enhancing 
lapse rates with potential for isolated strong/severe storms this 
afternoon and evening. See mesoscale discussion 1385 for more detailed information. 

..parts of northern/eastern Ohio into western PA... 
Satellite/radar animations suggest presence of an mesoscale convective vortex over Northern Ohio 
that is moving slowly eastward. A few stronger storms are associated 
with the mesoscale convective vortex at this time...and convective development may be 
enhanced downstream from the mesoscale convective vortex into this evening. For this 
reason...have extended the marginal risk area farther east/southeast across 
eastern Ohio into western PA where storms capable of producing gusty winds and 
marginally severe hail may occur. 

.Weiss/Dean.. 07/24/2016 


Mesoscale Discussion

acus11 kwns 241703 
sels mesoscale discussion 
Storm Prediction Center mesoscale discussion 241703 

Mesoscale discussion 1386 
National Weather Service Storm Prediction Center Norman OK 
1203 PM CDT sun Jul 24 2016 

Areas affected...portions of northern/eastern Ohio...western PA...the northern WV 

Concerning...severe potential...watch unlikely 

Valid 241703z - 241930z 

Probability of watch issuance...5 percent 

Summary...thunderstorms will continue to increase in number/intensity 
through the afternoon across parts of the upper Ohio Valley and 
vicinity. Locally strong thunderstorms -- some possibly approaching severe 
limits -- may occur...though ww issuance is not anticipated. 

Discussion...visible satellite loops and surface observations indicate a 
warm front advancing northeastward across parts of western PA and northestern Ohio...with 
dewpoints into the upper 60s/around 70f on the warmer side of this 
boundary. Broad cumulus fields SW of the warm front highlight the 
moist/destabilizing boundary layer. 

With little capping...and given forcing for ascent related to an mesoscale convective vortex 
moving eastward across the Cleveland area...a surface boundary moving southward 
across parts of northwestern/N-cntrl Ohio...differential-heating-induced 
baroclinicity on the edge of multi-layered clouds across Northern Ohio -- 
thunderstorms should continue increasing in coverage/intensity this 
afternoon. This activity will spread generally ewd/esewd. 

With moderately unstable air characterized by MLCAPE around 
1500-2000 j/kg continuing to build northeastward across the upper Ohio 
Valley...a few vigorous updrafts may evolve. The cle vwp suggests 
only around 20 knots of 0-6-km bulk shear present...though a few 
multicell clusters with locally damaging wind gusts could occur. 

Generally poor middle-level lapse rates and the lack of stronger deep 
shear should prevent a more substantial severe risk from evolving. 

.Cohen/Weiss.. 07/24/2016 

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


Latitude...Lon 40098064 40228191 40688315 41058336 41178292 41068169 
41328055 40967941 40267973 40098064