Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Springfield MO
754 PM CDT Wed Apr 1 2015
Short term...(late this afternoon and tonight)
issued at 336 PM CDT Wednesday Apr 1 2015
A large area of showers and thunderstorms developed this afternoon
due to a returning warm front and leftover mesoscale convective
vortex (mcv) from convection across Oklahoma on Tuesday. We have
received a few hail reports along with reports of strong
straight-line winds with a few embedded line segments (but no damage
to this point).
This activity will continue to shift northeast late this afternoon
and this evening although it will run into a drier low level air
mass. We may also see some redevelopment behind this main activity
early this evening as a low level jet stream strengthens. Most of
this activity should shift out of the area by late this evening.
We will then be watching additional convective development across
the Central Plains later tonight along a cold front. This activity
should begin to shift into extreme southeastern Kansas and
west-central Missouri before sunrise. Lows tonight should be pretty
close to 60 over most areas.
Long term...(thursday through wednesday)
issued at 336 PM CDT Wednesday Apr 1 2015
That front will then push into central Missouri Thursday morning but
will begin to stall. Showers and thunderstorms should overspread
most of the Missouri Ozarks Thursday morning. Activity should then
decrease in coverage for a time from late morning into early
afternoon as upper level short wave ridging occurs.
Convective re-development will then be possible later Thursday
afternoon...especially if we can see any sunshine. It remains a
tough call as to whether or not the cap will break and we will see
surface-based convection. Deep layer shear will easily be sufficient
for storm organization as a mid and upper level speed Max spreads
into the region. The orientation of the front when compared to wind
fields may not Bode well for supercells...although motions of any
discrete storms would tend to move along that boundary.
We will also have to watch any convection that can manage to
develop across eastern Oklahoma as it may stand a better chance of
being supercellular. This is also highly questionable given that
the cap may hold.
Otherwise, the main play from late Thursday afternoon into
Thursday night may actually be multicells and line segments with an
attendant straight-line wind and hail threat. Low level wind shear
vectors may also be supportive of embedded mesovortex potential
for anything bowing to the east or northeast (especially along
that front or any remaining outflow).
Surface low pressure will then track from the Southern Plains
through northern Arkansas or far southern Missouri from later
Thursday night into Friday morning. As this happens, that low level
jet will firm up and override that front. We are therefore looking
at widespread convective potential. We will have to watch the
Hydro situation closely. We considered a flood or Flash Flood Watch
with this forecast package. However, we would like to wait and see
where some key features begin to set up (e.G. Low level front and
main Theta-E advection) before honing in on a possible watch area.
We would also like to see how much rainfall we get tonight.
That front will then plow southeast later on Friday which will bring
an end to the precipitation threat. Brisk north winds will develop
with some areas possibly pushing Wind Advisory criteria. A decent
surface high will build south into the Central Plains Friday night
and will open the door for a decent frost setup with lows in the
upper 20s to lower 30s.
Low level winds will then shift back around to southerly by Sunday
as that high scoots southeast of the area. Gulf moisture will begin
to return early next week as the upper level flow GOES from flat to
southwesterly. This will likely result in unsettled weather
conditions with several opportunities for showers and thunderstorms
during the early and middle portion of next week. After that cool
start to the weekend, temperatures should warm to above normal
values by early next week.
Aviation...(for the 00z tafs through 00z Thursday evening)
issued at 744 PM CDT Wednesday Apr 1 2015
For the ksgf/kjln/kbbg tafs: scattered thunderstorms have moved
east of the taf sites for now. Thunderstorms ahead of a cold front
over the plains will move into the region toward 12z-15z with
MVFR/IFR conditions. Late in the taf period some thunderstorm re-
development will be possible but it will be hard to be precise on