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000
FXUS63 KEAX 191731
AFDEAX

AREA FORECAST DISCUSSION
National Weather Service Kansas City/Pleasant Hill MO
1231 PM CDT Sat Aug 19 2017

.Discussion...
Issued at 253 AM CDT SAT AUG 19 2017

Generally quiet short-term forecast as a surface ridge slides
across the region early this morning, although sufficient residual
moisture pooling behind yesterday`s boundary, combined with light
and variable winds will allow areas of patchy fog to develop over
the next few hours. Temperatures will rise into the upper 80s to
perhaps low 90s today, without morning cirrostratus to inhibit
diurnal temperature rises early in the day, and with a fairly dry
boundary layer preventing a thick cu field from developing in the
afternoon.

Convection is expected to develop across central NE/northwest KS
this evening and push eastward during the overnight hours,
possibly reaching the western edge of the forecast area by sunrise
Sunday. Cold pool propagation away from the parent shortwave
trough along with diminishing instability will cause these storms
to weaken as they head eastward, and will likely cause weakening
or altogether dissipation of the storms prior to arriving in our
area, so have stuck with fairly low PoPs for Sunday morning.
Residual outflow boundaries from the convection could help
convection fire across the region Sunday afternoon or evening,
but remains uncertain without knowing the evolution of tonight`s
convective complex.

A robust nocturnal LLJ will feed into a nearly stationary boundary
that will set up across central IA on Sunday night, and will kick
off widespread convection across IA by early Monday morning. These
storms will be driven southeastward by their cold pool, which
could be quite significant if storms train over one area for a
period of time. Several models including the NAM Nest drive the
outflow from these storms in northern MO after sunrise Monday,
likely with an associated accas deck and potentially serving as a
focus for additional storm development later in the day. Not all
models are this aggressive with the cold pool and the resolution
of these types of features is definitely a weakness in non-
convection allowing models, but it remains a possibility that a
boundary and associated low to midlevel cloud cover could linger
through Monday. Additional convection is expected further to the
southwest in broad zonal to west-southwest flow aloft, which most
models morph into a cirrus shield that also streams over the
forecast area on Monday. This type of cloud cover may not be as
detrimental to eclipse viewing, but is still not ideal.

The low-level jet will bend southward on Monday night, feeding
into southern IA and the MO/IA border region, resulting in another
round of nocturnal thunderstorms Monday night. Since these storms
will form closer to or in the forecast area, they are much more
likely to impact the majority of the CWA as they drive southeast-
ward, and could produce some significant rainfall for northern
portions of the CWA. Showers and storms may linger into Tuesday,
then will push southward as a strong upper trough pushes through
the Northern Plains into the Great Lakes region. After the Monday
night-Tuesday system departs, quieter and cooler conditions are
expected for the remainder of the forecast period.

&&

.Specifics for the Total Solar Eclipse on August 21st...
Issued at 253 AM CDT SAT AUG 19 2017

Consensus currently indicates that cirrus will stream through the
region on Monday, emanating from convection across the southern
and central High Plains. This cirrus may be thin enough not to
completely inhibit eclipse viewing, but the chances for clear
skies remains low. There is also a possibility that dying storms
across central and southern IA could push thicker, lower-based
cloud cover into northern and central MO that could linger into
the afternoon, and outflow/differential heating from the dying
convection could serve as a focus for additional storm
development during the afternoon. High-res guidance as it starts
to filter in will help immensely, since the thickest and most
detrimental cloud cover will be very dependent on convection,
which is not well resolved by the broader, longer-range models.

.Aviation...(For the 18Z TAFS through 18Z Sunday Afternoon)
Issued at 1231 PM CDT SAT AUG 19 2017

VFR conditions expected through the majority of the fcst period
with precip holding off until after the 09z time frame as
convection tracks east from the Central Plains during the predawn
hours. Current indications suggest this activity should be
undergoinga weakening trend as it arrives, and have decided to
just go with a VCTS mention for now. Otherwise, weak southeast
winds will persist through the fcst period.

&&

.EAX WATCHES/WARNINGS/ADVISORIES...
KS...NONE.
MO...NONE.
&&

$$

Discussion...Laflin
Eclipse...Laflin
Aviation...32