U.S. Severe Weather Forecast (Convective Outlook)

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Day Three

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Storm Prediction Center ac 190820 


Day 3 convective outlook 
National Weather Service Storm Prediction Center Norman OK 
0220 am CST Tue Feb 19 2019 


Valid 211200z - 221200z 


..no severe thunderstorm areas forecast... 


... 
the risk of severe thunderstorms appears negligible across the U.S. 
Thursday through Thursday night. 


... 
Some further amplification of large-scale mid/upper troughing inland 
of the Pacific coast appears possible during this period, as a 
vigorous embedded short wave impulse continues digging into its 
base, and gradually pivots across Southern California and the 
adjacent southwestern international border area. Although not quite 
yet coming in-phase with the subtropical stream, models suggest that 
it may become increasingly so toward the end of the period. 


Downstream, broad mid/upper ridging is forecast to continue to build 
across much of the nation to the east of The Rockies, to the 
north/northwest of a subtropical ridge, centered at mid-levels 
east/southeast of the Bahamas. A remnant short wave impulse will 
progress around the crest of the ridge, before digging across New 
England and the Canadian Maritimes into the Atlantic. A developing 
frontal wave, near the northern mid Atlantic coast at 12z Thursday, 
is expected to rapidly deepen and become the primary associated 
cyclone as it migrates away from the coast Thursday through Thursday 
night. 


A quasi-stationary frontal zone trailing from this low, across the 
mid Atlantic and southern Appalachians through the lower Mississippi 
Valley and Texas Gulf Coast at 12z Thursday, may remain a focus for 
continuing weak thunderstorm activity early Thursday. This may 
persist through much of the period, as a continuing southerly return 
flow of moisture off the Gulf of Mexico maintains weak 
destabilization in a corridor across and above it. However, this 
boundary is expected to gradually shift or redevelop northward 
beneath the building upper ridge, with the corridor of highest 
thunderstorm probabilities expected to become focused across 
northeast Texas and the Ozark Plateau/mid south/Tennessee Valley 
region by late Thursday night. 


Meanwhile, weak thunderstorm activity may also develop across parts 
of the Rio Grande Valley into central Texas by Thursday night, 
aided by elevated moisture return and destabilization associated 
with the belt of westerlies emanating from the subtropical eastern 
Pacific. 


It also appears that the strong digging western impulse may 
contribute to weak destabilization and low-topped convection capable 
of producing lightning near the Southern California coast, and 
across parts of central Arizona, Thursday into Thursday night. 


.Kerr.. 02/19/2019 


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