U.S. Severe Weather Forecast (Convective Outlook)

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Storm Prediction Center ac 191616 


Day 1 convective outlook 
National Weather Service Storm Prediction Center Norman OK 
1116 am CDT Thu Oct 19 2017 


Valid 191630z - 201200z 


..there is a marginal risk of severe thunderstorms over southern 
New Mexico and far West Texas... 


... 
Isolated marginally severe hail and thunderstorm gusts are possible 
this afternoon into early evening over a portion of southern New 
Mexico and far West Texas. 


..southern New Mexico and far West Texas... 


In wake of lead impulse over southeast nm, a secondary vorticity 
maximum located over central Arizona will advance east today, reaching 
nm later this afternoon into evening. Between these two features, 
visible satellite imagery shows an area of clearing spreading east 
through southwest toward south-central nm where surface dewpoints 
are near 50f. Diabatic warming in presence of steep mid-level lapse 
rates will contribute to marginal (400-800 j/kg) MLCAPE and deeply 
mixed, inverted-v boundary layers this afternoon. Thunderstorms are 
expected to develop over the higher terrain of central through 
southwestern nm and increase in coverage with approach of deeper 
forcing for ascent attending the upstream shortwave trough. While 
vertical shear will remain weak and supportive of multicells, the 
thermodynamic environment will promote at least a marginal risk for 
a few instances of hail and locally strong wind gusts later this 
afternoon into early evening. 


.Dial.. 10/19/2017 


$$ 

Mesoscale Discussion


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Storm Prediction Center mesoscale discussion 151903 
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Mesoscale discussion 1719 
National Weather Service Storm Prediction Center Norman OK 
0203 PM CDT sun Oct 15 2017 


Areas affected...from eastern Ohio across Pennsylvania and into 
western/central New York 


Concerning...severe potential...watch possible 


Valid 151903z - 152000z 


Probability of watch issuance...40 percent 


Summary...a narrow line of low-topped showers and thunderstorms will 
develop eastward with a threat of strong to severe wind gusts this 
afternoon. 


Discussion...multiple segments of low-topped showers and storms are 
developing from southwest Ontario into eastern Ohio along an 
intensifying cold front. The strongest area of lift currently exists 
over Canada, and this is where sporadic lightning activity is 
occurring. 


Surface observations show gradually warming temperatures, with 
dewpoints in the lower 60s. The deeper moist plume exists mainly 
just ahead of the front, with drier air/lower precipitable water values from the 
Appalachians into New England. Temperatures aloft are not very cold 
except for well behind the front into Michigan, leading to only weak 
cape values. In addition, much of the instability exists mainly in 
the parts of the atmosphere. 


With mean winds in excess of 40 kt in the lowest few km, these 
showers and storms along the cold front will likely Transfer 
momentum to the surface with 40-50 mph wind gusts possible, and 
perhaps an isolated severe gust. The most likely area for severe 
winds would appear to be over New York where mean wind speeds are 
strongest, and in closest proximity to the shortwave trough. In 
addition, veering winds with height and sufficient srh may result in 
embedded areas of rotation in qlcs fashion. This, however, will be 
dependent on sufficient instability being present. Ample heating 
over New York lends some confidence of this possibility. 


.Jewell/Hart.. 10/15/2017 


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


Attention...WFO...btv...aly...bgm...buf...ctp...pbz...cle... 


Latitude...Lon 45137382 44617383 43857421 42877523 41847651 40797811 
40338016 40308120 40628143 41138132 41808085 42798018 
43597918 43997754 44407616 44927537 45137464 45137382