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

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000
FXUS63 KEAX 140836
AFDEAX

AREA FORECAST DISCUSSION
National Weather Service Kansas City/Pleasant Hill MO
336 AM CDT Mon May 14 2018

.Discussion...
Issued at 331 AM CDT MON MAY 14 2018

A shift in the weather pattern today with front finally progged
to push southward tonight and Tuesday. Also, expect a bit more
action today weather-wise as compared to the previous several days.
Ongoing morning convection across portions of southeast Nebraska,
southwest Iowa, and far northwest Missouri will reinforce the
frontal boundary and help shift it a bit further south this
morning/early afternoon. Increasing mid-level moisture and slight
cooling in the mid-levels will allow the stubborn 850-700mb cap to
weaken significantly by early afternoon. The 5Z HRRR has
convection breaking out across much of the forecast area by 18-19Z
(1-2 pm), but the NAM and RAP are holding off convection until
much later in the afternoon...and focus convection across
northeast KS and northwest Missouri moving it southward with time.
The NAM eventually develops an MCS feature that will push into
eastern Missouri around midnight but is also hinting at a second
round of storms across western Missouri after 00Z. Previous runs
of the HRRR also had a similar scenario of convection initiating
across northwest Missouri and eventually merging into an MCS that
works east with time. Current thinking is that we might see a
combination of these scenarios with convection across northwest
Missouri and scattered convection in the warm sector eventually
merging and racing east along the the front and instability
gradient once the MCS becomes more cold pool dominant.

Dewpoints in the mid to upper 60s and steep lapse rates will lead to
a moderate to strongly unstable environment. Mixed-layer CAPE
values of 2000-3000 J/kg will allow for strong updrafts and
despite the lack of deep layer shear, storms should be capable of
large hail. Given steep lapse rates, damaging winds will also be a
concern. As the storms merge and begin to translate east...the
hail threat will transition into more of a wind threat. Storm
motion should be relatively slow and with PWAT values of 1.5 to
1.75" and boundary in the region...the likelihood of heavy rain
will also be a concern. However, with this said...there is still
quite a bit of uncertainty as to how today will play out given the
frontal position and morning convection possibly impacting
convection later today.

By Tuesday morning, we could still see a few lingering showers and
cooler temperatures settling in on the backside of the front. The
Rex block across the western conus will begin to break down
Wednesday. Periodic rain chances will continue through the
remainder of the week with the best chance this weekend with the
approach of another cold front.

&&

.Aviation...(For the 06Z TAFS through 06Z Monday Night)
Issued at 1046 PM CDT SUN MAY 13 2018

VFR conditions are expected for the TAF period, with the main
concern being pinning down timing for storm chances. For tonight,
northeast KS and far northwest MO have the best chance for seeing
nocturnal convection along the boundary as the LLJ ramps up.
The activity should start diminishing in the early morning hours
as the LLJ weakens. Tomorrow, diurnal cumulus and gusty winds are
expected again with some storm chances across much of the area,
though there is not great consensus on where afternoon storms
will develop. Northeastern KS and northwestern MO have the greater
chance in the afternoon to see isolated storms before the
activity becomes widespread in the evening. This is when the
boundary will finally push through the area in conjunction with a
LLJ. Most likely a line of convection, oriented southwest to
northeast, will move to the southeast through the entire area at
the end of the TAF period.

&&

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

$$

Discussion...Pietrycha
Aviation...Grana



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