U.S. Severe Weather Forecast (Convective Outlook)

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swody1 
Storm Prediction Center ac 240559 


Day 1 convective outlook 
National Weather Service Storm Prediction Center Norman OK 
1259 am CDT Sat Jun 24 2017 


Valid 241200z - 251200z 


..there is a marginal risk of severe thunderstorms early over 
portions of coastal southern New England... 


..there is a marginal risk of severe thunderstorms over portions of 
the Carolinas and northeast Georgia... 


..there is a marginal risk of severe thunderstorms over portions of 
New Mexico... 


... 
Isolated severe thunderstorms with damaging winds will be possible 
over portions of the southeast on Saturday, with isolated severe 
hail and strong winds over parts of New Mexico. Isolated damaging 
winds and perhaps a brief tornado will be possible across southern 
New England Saturday morning. 


... 
Within a broad cyclonic mid-level flow regime from the 
central/northern plains east to the northeast U.S., A notable 
embedded impulse will move southeast across the upper Midwest and 
Great Lakes on Saturday. In response, slight amplification of the 
upper-level trough will occur and an increase in mid-level flow will 
occur across the Carolinas/portions of the mid-Atlantic region. 
Farther west, an upper-level anticyclone will strengthen in the 
vicinity of the Arizona/Mexico border. A surface cold front will 
extend near the New England coast southwest across the Carolinas, 
and west through the lower Mississippi Valley/central Texas and then 
curving north across the high terrain of New Mexico Saturday 
afternoon. A very moist (upper 60s/lower 70s surface dew points) 
air mass will remain in place south of the frontal boundary. 


... 
Diurnal heating of a very moist air mass along and south of the 
front will result in pockets of moderate MLCAPE by afternoon, and 
moderate southwesterly flow aloft will result in 30-40 kts of 
effective shear. Despite generally weak low-level flow, updraft 
water loading in the presence of precipitable water values in excess of 2 inches 
should result in isolated strong/damaging gusts with the strongest 
storms during the afternoon and early evening hours. 


..New Mexico... 
Southeasterly low-level flow will continue to transport increasing 
moisture into the high terrain Saturday, and areas of moderate 
surface-based instability will develop during the afternoon. 
Thunderstorms developing near the Continental Divide in the presence 
of 20-35 kts of northwest mid-level flow may become sufficiently 
organized with mid-level rotation to pose a risk for isolated large 
hail. In addition, the presence of a well-mixed boundary layer will 
promote a risk for damaging winds. 


..coastal southern New England early... 
Forecast soundings depict strong low-level wind fields and 
unidirectional flow in advance of the front during the morning 
hours, in part due to a notable southerly low-level jet from near 
the mid-Atlantic coast into southern New England. Although 
instability will be meager, some high-res guidance continues to 
suggest a potential for short line segments near the immediate 
coast, and will introduce a focused area with low severe 
probabilities for isolated damaging winds and perhaps a tornado. 


..lower Mississippi Valley into central Texas... 
Although mid-level flow and deep-layer shear will be generally weak 
across this area, at least some potential for strong/severe storms 
may exist during the afternoon as storms diurnally intensify in the 
vicinity of the front or perhaps along remnant outflow from prior 
convection. With moderate instability expected to develop, severe 
probabilities may be introduced in later outlooks where confidence 
in greater storm coverage increases. 


.Bunting/Mosier.. 06/24/2017 


$$ 

Mesoscale Discussion


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sels mesoscale discussion 
Storm Prediction Center mesoscale discussion 240525 cor 
ncz000-scz000-240715- 


Mesoscale discussion 1144 
National Weather Service Storm Prediction Center Norman OK 
1225 am CDT Sat Jun 24 2017 


Areas affected...central North Carolina 


Concerning...severe potential...watch unlikely 


Valid 240525z - 240715z 


Corrected to change WSR-88D vwp reference to Roanoke, Virginia 


Probability of watch issuance...20 percent 


Summary...an isolated wind damage threat may develop across central 
North Carolina over the few hours. However, the threat is expected 
to remain marginal and weather watch issuance is not expected. 


Discussion...radar imagery shows the remnants of Cindy moving 
eastward across the southern and central Appalachians. A couple 
bands of convection are ongoing across western Virginia extending 
southward into western North Carolina. The airmass ahead of this 
convection is very moist with surface dewpoints in the 70s f across 
much of North Carolina which is resulting in a corridor of moderate 
instability across the Piedmont of North Carolina. MLCAPE values are 
estimated in the 1000 to 2000 j/kg range from near the NC-SC 
Stateline extending northeastward into southeastern Virginia. In 
addition, the WSR-88D vwp at Roanoke, Virginia shows a strong deep-layer 
shear profile with 0-6 km shear of 50 to 55 kt and substantial speed 
shear in the lowest 1km above ground level. This appears representative of the 
environment in central North Carolina and may support an isolated 
wind damage threat as the line segment moves eastward into central 
North Carolina over the next couple of hours. The latest cam 
solutions suggest that the line that is currently in west-central 
North Carolina may persist for a couple more hours and then weaken. 
This seems reasonable and weather watch issuance remains unlikely 
due to the short duration that is expected for any wind damage 
threat. 


.Broyles/dial.. 06/24/2017 


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


Attention...WFO...rah...ilm...rnk...cae...gsp... 


Latitude...Lon 35007822 34747989 34798055 35228086 35988002 36407917 
36097801 35007822