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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
