Scientific Forecaster Discussion
fxus63 ksgf 291134
Area forecast discussion
National Weather Service Springfield MO
634 am CDT Thu Jun 29 2017
..12z aviation update...
Short term...(today and tonight)
issued at 235 am CDT Thu Jun 29 2017
Will monitor the southern extent of convection over northern MO
in the near term. Weak outflow boundary has made it into central
MO, but is weakening. Convection, or what's left of it, lags the
sfc boundary, so at this point not expecting much.
It will be another very warm and somewhat breezy day today.
Another mesoscale convective system is expected to develop/grow upscale from the corn
belt southwest into Kansas this afternoon and this evening as another
in series of shortwave impulses move form the plains into the
Midwest. This area is expected to move se or SSE as a low level
jet increases and it will have a better chance to move into our
forecast area this evening and overnight versus what we've had
tonight. While a weakening trend is expected tonight, strong/severe
winds may occur along/near the leading edge of the storms over
our northern counties. Convective allowing models (cams) vary on
the degree and timing of the weakening, but in general low level
vertical Thermo profiles become less favorable with some capping.
Some lift behind the outflow boundary may allow some elevated
convection to develop farther south toward or just south of the
I-44 corridor late tonight.
Long term...(friday through wednesday)
issued at 333 am CDT Thu Jun 29 2017
Looks like an active period for thunderstorms throughout much of
this time. Heavy rainfall/potential flooding will also need to be
monitored as individual storm complexes/clusters move through the
Friday-Friday night: convective boundaries/cold front will move
through the region during this time as a jet streak/shortwave
moves from the central rockies into eastern Kansas and MO by early
evening. Strong afternoon instability (2000-2500 j/kg) ahead and
vertical shear with 0-6km 30-50kts M/l will be in place for
organized storms as limited capping breaks in the afternoon.
Initial development/redevelopment should occur along low level
convergence boundaries mid/late afternoon with large hail and
damaging winds the primary threats. Couldn't rule out a tornado
early on as storms develop given the potential shear/vertical
Thermo combination. Convection should gradually shift southeast
We will also have to monitor for areas of heavy rainfall,
especially over southern MO as the front becomes more W-E
oriented late Fri-Fri night. Wpc is bullish on rain amounts. Fcst
database/grids/blends are not as bullish, but the overall setup
could be conducive for storm training depending on the small
Saturday-Saturday night: global models vary on how far south the
front and precip will get pushed Sat/Sat night. The 00z European model (ecmwf) and
gdps push the rain farther south versus the GFS. Split the
difference and left some lingering rain chances in for Saturday,
primarily in the morning.
Sunday-Monday-Monday night: yet another shortwave is expected
to move into the Central Plains/eastern Kansas by midday Sunday with
the front lifting back to the north over Kansas/western MO. Will
probably see additional small scale waves into Monday, but by this
time the mesoscale picture is Muddy. With a diffuse boundary
expected to be in place with abundant moisture, it looks like a
good set up for periodic storms.
Tuesday July 4th-wednesday: another shortwave will approach, but
as an upper level ridge builds over the western conus, the
downstream shortwave separates from the main belt of westerlies
and slowly moves southeast into the region. Guidance is all over
the place with this overall pattern change, but the common theme
is the same, unsettled weather with chances for showers/storms.
Aviation...(for the 12z tafs through 12z Friday morning)
issued at 634 am CDT Thu Jun 29 2017
Generally, VFR conditions can be expected this taf cycle. There
is a little bit of uncertainty toward the early morning hours on
Friday of perhaps some ts development for jln and sgf. If
convection does form, expected cloud bases and vis to be impacted
at least to some extent.
Southerly winds will increase again, especially for jln and sgf
similar to yesterday, though not as gusty. Southerly flow will
begin to transition to southwesterly flow with time and should
lighten closer to sunset. Also similar to last night, there is a
signal for a marginal low level wind shear threat. Left mention of that out for
now, but it may be added at some point in later updates.