U.S. Severe Weather Forecast (Previsione fenomeni)

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Storm Prediction Center ac 261941 


Day 1 convective outlook 
National Weather Service Storm Prediction Center Norman OK 
0141 PM CST sun Feb 26 2017 


Valid 262000z - 271200z 


..there is a marginal risk of severe thunderstorms from central 
through northeast Texas into northern Louisiana... 


... 
Thunderstorms are expected to develop from central to northeast 
Texas this evening and spread into northern Louisiana tonight. A 
few instances of large hail are possible with the strongest 
activity, and a marginal risk for strong to damaging wind gusts will 
also exist, especially from far eastern Texas into northern 
Louisiana. 


..northeast Texas into northern Louisiana... 


The primary change to previous outlook has been to expand the 
marginal risk area farther east into northern la to account for the 
possibility of a few instances of strong to damaging wind gusts. 
Storms are expected to develop in evolving warm advection regime 
from central through northeast Texas this evening in association with a 
progressive, low-amplitude shortwave trough. Initial storms will 
likely be at least slightly elevated with some threat for large 
hail. However, consensus among cams is that activity will eventually 
evolve into a forward propagating mesoscale convective system. This suggests at least a 
marginal threat will exist for a few strong to damaging wind gusts 
from far eastern Texas into northern la later tonight. 


.Dial.. 02/26/2017 


Previous discussion... /issued 1025 am CST sun Feb 26 2017/ 


..northeast Texas... 
Morning water vapor loop shows a low-amplitude shortwave trough 
digging across Southern California. Weak mid-level height falls and 
strengthening southwesterly low-level winds ahead of this system 
over Texas will result in warm advection and lift, with scattered 
showers and thunderstorms forming later this afternoon and evening. 
Forecast soundings suggest that elevated cape values of up to 1500 
j/kg may develop, along with favorable deep layer shear for a few 
rotating storms. Hail will be the main threat from isolated 
stronger cells. At this time, the overall severe threat appears 
marginal. 


$$ 

Mesoscale Discussion


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Storm Prediction Center mesoscale discussion 252324 
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Mesoscale discussion 0214 
National Weather Service Storm Prediction Center Norman OK 
0524 PM CST Sat Feb 25 2017 


Areas affected...southeastern Vermont...southern New Hampshire...far southern 
ME...MA...eastern CT...and Rhode Island 


Concerning...severe potential...watch unlikely 


Valid 252324z - 260030z 


Probability of watch issuance...20 percent 


Summary...a watch downstream of Severe Thunderstorm Watch 40 is 
unlikely due to an unfavorable airmass. 


Discussion...radar imagery as of 2315z shows a bowing line of 
thunderstorms across the lower Hudson Valley of New York moving into the 
eastern part of Severe Thunderstorm Watch 40. These thunderstorms 
have recently (2244z) produced a measured severe wind gust of 69 mph 
at the Montgomery Airport in Orange County NY, along with some tree 
damage. As this convection continues eastward along a cold front 
into much of the remainder of New England, it is expected to quickly 
weaken due to a stable airmass. Southeasterly winds off the Atlantic 
across this region have prevented appreciable destabilization into 
much of Massachusetts/CT/RI/VT/NH, with rap mesoanalysis suggesting MUCAPE of 
100 j/kg or less downstream of the ongoing convection. While a very 
isolated strong to damaging wind threat may persist slightly to the 
east of the current Severe Thunderstorm Watch, downstream watch 
issuance is unlikely due to the hostile thermodynamic environment. 


.Gleason/guyer.. 02/25/2017 


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


Attention...WFO...gyx...box...btv...okx...aly... 


Latitude...Lon 42797276 43677238 43627091 43257041 42537060 41367116 
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