U.S. Severe Weather Forecast (Previsión convectiva)

día tres

acus01 kwns 170541 
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

acus11 kwns 170646 
sels mesoscale discussion 
Storm Prediction Center mesoscale discussion 170646 

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 

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... 


Latitude...Lon 40889127 41239317 41709455 42649404 42989286 42679145 
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