Area Forecast Discussion
Issued by NWS Kansas City/Pleasant Hill, MO

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FXUS63 KEAX 191154
AFDEAX

AREA FORECAST DISCUSSION
National Weather Service Kansas City/Pleasant Hill MO
654 AM CDT Sat May 19 2018

.Discussion...
Issued at 443 AM CDT SAT MAY 19 2018

The primary forecast challenge will be focused on the short-term
period, generally this morning through Sunday morning. Several
rounds of convection are expected to move through the forecast area,
with all modes of severe possible...especially later this afternoon
and evening. However, each round of storms will impact later rounds;
thus, there is still a bit of uncertainty as to how each potential
round of storms may play out.

This Morning: Models have been pretty consistent with tracking this
mornings MCS up into northeast Kansas and northwest Missouri.
Current radar trends have the southern half of the MCS a bit further
south than models tend to place it, so could see some storms make
their way into west-central Missouri...including the KC metro. Gusty
winds, and maybe a bit of small hail, is all that is expected as
this system begins to decay this morning. Further east across
central Missouri...dense fog has developed behind the upper low
that has been positioned over the region the past few days. Fog is
expected to mix out by 9 am this morning with improving
visibilities.

This Afternoon and Evening: Focus then shifts towards this afternoon
and evening with shortwave trough ejecting out of the central
Rockies. Higher resolution models have morning MCS gradually
weakening with time, with a period of clearing during the late
morning into early afternoon. The longer range models are not as
ambitious with clearing things out and if that scenario plays
out...could impact overall severe threat. If we are able to clear
out, we have a decent chance of recovering by late afternoon. But
if cloud cover hangs around and continued showery activity...this
could put a damper on afternoon storms. That said, the overall
potential for severe weather remains high with hail, damaging
winds, and a few tornadoes possible.

Surface low will deepen by this afternoon as it moves up into
Kansas. The attendant warm front will surge northward and should be
across northern Missouri by this evening. The low-level jet will
ramp up this afternoon with general speed axis positioned from
central Texas northward to eastern Kansas. Shear values 40-50 kts in
the 0-6 km range and CAPE values of 2500-3500 J/kg will allow for
strong rotating updrafts. Steep mid-level lapse rates in the hail
growth zone will be favorable for large hail. The aforementioned
trough will becoming an important forcing agent this afternoon, with
initial storms expected to be more supercellular in nature and
transition to a more linear system as storms merge and translate
eastward in the vicinity of the warm front. Model derived
hodographs continue to show a nicely curved graph and conditions
look supportive of tornadoes near the triple point. As the storms
merge and become more linear, the southwesterly jet looks to favor
a decent QLCS set-up later tonight with a few quick spin-ups
possible. The MCS will weaken over northeast Missouri and
southeast Iowa early Sunday.

Sunday: Showers and thunderstorms are once again possible with a bit
of wrap-around activity and some redevelopment along old outflow
boundaries.

Monday-Friday: A bit cooler for Monday with warmer temperatures
returning by Tuesday. Periodic chances for showers and thunderstorms
through much of the week as we generally remain in southwest flow
aloft. Late in the week looks to be our best chance for wide-spread
rain chances with the passage of a cold front.

&&

.Aviation...(For the 12Z TAFS through 12Z Sunday Morning)
Issued at 640 AM CDT SAT MAY 19 2018

A potentially complicated TAF period with severe rounds of rain
and thunderstorms possible. The current round of convection will
work northeast with time and is expected to weaken and dissipate
later this morning. The next round of convection is expected
to develop between 22Z-00Z this afternoon with storms exiting the
vicinity of the terminals near 03Z-06Z. Scattered rain showers on
the backside of the upper level trough may linger into early
morning Sunday. The complications in the forecast are due to how
this early morning activity will impact afternoon storms. For now,
have trended current forecast towards hi-res model timing and
area. However, the forecast could change if morning storms
continue into the early afternoon.

&&

.EAX WATCHES/WARNINGS/ADVISORIES...
KS...NONE.
MO...Dense Fog Advisory until 9 AM CDT this morning for MOZ008-017-
     025-033-040-046.

&&

$$

Discussion...Pietrycha
Aviation...Pietrycha


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