U.S. Severe Weather Forecast (Convective Outlook)

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Day Three

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Storm Prediction Center ac 160811 


Day 3 convective outlook 
National Weather Service Storm Prediction Center Norman OK 
0211 am CST Sat Feb 16 2019 


Valid 181200z - 191200z 


..no severe thunderstorm areas forecast... 


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


... 
Although embedded short wave developments remain somewhat unclear, 
models indicate that larger-scale western U.S. Mid-level troughing 
may undergo some amplification during this period. It appears that 
this will occur as another in a series of short wave perturbations 
digs inland of the Pacific coast: this one to the south/southwest of 
the preceding impulses, across the southwestern international border 
area. 


Downstream, while mid-level subtropical ridging centered near/east 
of the Bahamas remains prominent, short wave ridging within the 
mid-latitude westerlies is forecast to build, in phase with the 
subtropical stream, across lower portions of the Southern Plains 
into the lower Ohio and Tennessee valleys. As a vigorous short wave 
impulse digs within a branch of westerlies to the north, to the 
southwest of Hudson Bay, it appears that increasingly confluent 
mid-level flow will support the southeastward development of the 
center of an expansive cold surface ridge, across the northern 
plains through southern portions of the Great Lakes region. 


The shallow southern/leading edge of the cold surface-based air 
appears likely to advance off the South Atlantic coast, while 
remaining quasi-stationary, beneath the mid-level ridging, across 
northern portions of the Florida Peninsula through much of the 
remainder of the northern Gulf Coast vicinity. Above it, a 
southerly return flow will be maintained, including further 
moistening off a modifying boundary layer over the western Gulf of 
Mexico, into the western and central Gulf Coast states. 


In the presence of weak (but increasing) elevated instability, 
modest strengthening of the return flow (including 30-40 kt at 850 
mb) may be accompanied by steepening isentropic ascent supportive of 
increasing potential for scattered thunderstorm development by late 
Monday night. Depending on the magnitude of cape and depth of the 
convective layer, the environment could become conducive to severe 
hail in the presence of strong vertical shear, mainly in a narrow 
corridor roughly across central Louisiana and adjacent portions of 
Texas and Mississippi. However, due to a number of lingering 
uncertainties, including timing near the end of the period, severe 
probabilities still appear less than 5 percent at the present time. 


.Kerr.. 02/16/2019 


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