U.S. Severe Weather Forecast (Конвективни Outlook)

Day Three

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Storm Prediction Center ac 141627 

Day 1 convective outlook 
National Weather Service Storm Prediction Center Norman OK 
1127 am CDT Tue Aug 14 2018 

Valid 141630z - 151200z 

..there is a slight risk of severe thunderstorms over parts of 
northeast Wyoming... 

A few severe thunderstorms are possible this afternoon into evening 
over parts of the north-central rockies/High Plains region. Other 
strong storms may occur over eastern North Carolina, portions of 
Oklahoma and southern Kansas, and southern Arizona. 

Morning water vapor loop shows a deepening upper trough over western 
Mt/WY. This feature will track eastward across Wyoming today, providing 
large scale forcing for ascent and scattered thunderstorm 
development. Southeasterly low level winds east of the big horns 
will maintain ample moisture, with afternoon heating yielding steep 
low level lapse rates and MLCAPE values of 1000-1500 j/kg. Given 
the favorable vertical shear profiles, steep mid-level lapse rates, 
and consensus of 12z guidance that several storms will form, have 
upgraded portions of this region to slight risk for large hail. 
Activity may persist well into the evening, spreading eastward into 
parts of western South Dakota/Nebraska before diminishing. 

Several vort maxima continue to rotate around an upper low over 
western Kansas. Broken cloud cover will help to destabilize a corridor 
over much of OK and southeast Kansas today, leading to moderate cape 
values and scattered thunderstorm development. Deep layer shear is 
marginal. However, strengthening low level flow this 
afternoon/evening and ambient vorticity beneath cyclonic flow field 
may be sufficient for a few rotating cells capable of damaging wind 
gusts, an isolated tornado or two, and perhaps hail. 

Full sunshine and dewpoints in the 70s are leading to MLCAPE values 
of 1500+ j/kg over eastern NC today, beneath moderately strong 
westerly flow aloft. Scattered thunderstorms will continue to 
develop in this region and spread eastward toward the coast. Steep 
low-level lapse rates and sufficient cape will lead to a few 
multicell clusters capable of gusty/damaging wind gusts. Refer to 
recent mesoscale discussion #1285 for further details. 

12z guidance is becoming more consistent in the likely development 
of clusters of thunderstorms forming in Southeast Arizona later this 
afternoon and spreading eastward across southern Arizona overnight. 
Ample low level moisture and cape, coupled of steep low level lapse 
rates, will promote strong outflow winds in the stronger cells. 

.Hart/squitieri.. 08/14/2018 


Mesoscale Discussion

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sels mesoscale discussion 
Storm Prediction Center mesoscale discussion 141610 

Mesoscale discussion 1285 
National Weather Service Storm Prediction Center Norman OK 
1110 am CDT Tue Aug 14 2018 

Areas affected...eastern North Carolina 

Concerning...severe potential...watch unlikely 

Valid 141610z - 141815z 

Probability of watch issuance...20 percent 

Summary...storms are expected to increase in coverage over the next 
few hours with isolated severe hail or wind possible. 

Discussion...visible satellite shows an expanding cumulus field across 
central and southeast NC, with the northern edge coincident with 
more substantial moisture and acting as an effective warm front. 
Continued heating will result in moderate instability, which will 
favor strong updrafts. As of 16z, an isolated cell was already 
ongoing across central NC, and this storms should persist as it 
travels eastward along the lifting boundary. Other cells may 
eventually develop on its southwest flank, where towering cumulus were developing 
toward the SC border. West/southwest 850 mb flow will result in weak 
warm advection into northeast NC as well, supporting any cells that 
move leftward into that area. 

Shear profiles are only marginally supportive of long-lived storm 
potential as midlevel flow is around 35 kt with weak low-level 
winds. However, increasing instability going into the peak heating 
hours and ample precipitable water should allow storms to be 
maintained for a while, propagating eastward with strong outflow and 
marginal hail. 

.Jewell/Hart.. 08/14/2018 

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


Latitude...Lon 35707897 35887861 36257685 36187639 35917605 35507586 
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