U.S. Severe Weather Forecast (Конвективни Outlook)

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Day Three

000 
acus01 kwns 170541 
swody1 
Storm Prediction Center ac 170540 


Day 1 convective outlook 
National Weather Service Storm Prediction Center Norman OK 
1140 PM CST Sat Feb 16 2019 


Valid 171200z - 181200z 


..no severe thunderstorm areas forecast... 


... 
a few thunderstorms are expected over a portion of the southeast 
states as well as California. 


..southeast states... 


A low-amplitude shortwave trough over the Central Plains will move 
east northeast today, reaching the Ohio and Tennessee valleys later this 
afternoon and evening, preceded by a minor impulse. A southerly 
low-level jet will strengthen across the southern Appalachians 
within exit region of an intense upper jet located within base of 
the shortwave trough. A few thunderstorms may be ongoing by 12z over 
the Tennessee Valley in association with the lead impulse. In wake of this 
feature, low-level Theta-E advection along the warm conveyor belt 
will promote a corridor of very marginal instability in the presence 
of weak mid-level lapse rates. Additional showers and a few 
thunderstorms are expected to develop within cold frontal zone as it 
advances eastward later today and evening. 


..California through Great Basin region... 


Steep mid-level lapse rates resulting from cold air aloft will 
persist within the broad circulation of a large upper trough, 
contributing to very weak instability with 100-300 j/kg MUCAPE. 
Vorticity maxima moving through this feature will promote areas of 
showers as well as a few embedded thunderstorms. Isolated 
thunderstorms will be possible farther east into the Great Basin, 
especially as the boundary layer destabilizes this afternoon. 
However, coverage will probably remain less than 10%. 


.Dial/squitieri.. 02/17/2019 


$$ 

Mesoscale Discussion


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acus11 kwns 170646 
sels mesoscale discussion 
Storm Prediction Center mesoscale discussion 170646 
iaz000-ilz000-171045- 


Mesoscale discussion 0106 
National Weather Service Storm Prediction Center Norman OK 
1246 am CST sun Feb 17 2019 


Areas affected...central into eastern Iowa 


Concerning...heavy snow 


Valid 170646z - 171045z 


Summary...heavy snow, with up to 1 inch/hr snowfall rates, is 
expected to continue for a few more hours. 


Discussion...a mid-level shortwave trough continues to impinge on 
the discussion area, with strong divergence noted at 300 mb 
associated with the left-exit region of a pronounced jet streak. As 
such, adequate upper-level support for ascent remains in place to 
encourage the lifting of saturated parcels through a deep dendritic 
growth layer (-12 to -17 c), where heavy snow will remain possible, 
including at least brief occasions of 1 in/hr snowfall accumulation 
rates. 


As sunrise approaches, the intensity of the primary band of snow is 
expected to wane, with much lower snowfall rates expected per latest 
high-resolution model guidance. 


.Squitieri.. 02/17/2019 


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


Attention...WFO...dvn...arx...dmx... 


Latitude...Lon 40889127 41239317 41709455 42649404 42989286 42679145 
42099056 40949059 40889127