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

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000
FXUS63 KEAX 051732
AFDEAX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE KANSAS CITY/PLEASANT HILL MO
1232 PM CDT Tue May 5 2015

.DISCUSSION...
Issued at 319 AM CDT TUE MAY 5 2015

For today, we should see very warm temperatures with enough humidity
to make things feel more uncomfortable than is normal for this time
of year. High temperatures look to climb into the low to mid 80s for
most locations. While most of the area looks to remain dry, there
will be a chance for some diurnally driven showers and storms in
mainly our southern zones. Forecast soundings in our south show an
uncapped environment with convective temperatures being exceeded by
the early afternoon. Several models also move some showers/storms
north during the day from southern Missouri. This activity looks to
be more isolated in nature, since there is no larger scale forcing to
drive things. However, remnant out flow boundaries from last
evening`s convection may be present and aid in development. The
severe potential looks relatively low with only modest CAPE and weak
shear. This activity should diminish with the loss of daytime heating
and as a result there should be a lull in activity from the early
evening hours until the predawn hours on Wednesday.

For Wednesday, a strong negatively tilted shortwave trough is
expected to eject into the Plains from the main long wave trough over
the western states. This will initiate what may be vigorous
convection in western Kansas and Oklahoma Tuesday afternoon and
evening. It then looks like this activity will be forced eastward
through the night ahead of the advancing shortwave trough and along
a strong low level jet with strong moisture transport nosing into
eastern Kansas and western Missouri. Models show instability weakening
with eastward progression of this potential convective system. Shear
also decreases further east, as one moves away from the stronger mid
to upper level winds closer the shortwave. So it looks like a
weakening line of convection is possible early Wednesday morning for
eastern Kansas and western Missouri. With the weak instability and
weak shear, the threat of severe weather Wednesday morning looks low.
That system, and its cloud cover, look to have an effect on our weather
throughout the day Wednesday. So temperatures should only climb into
the low to mid 70s as a result. As is the case this time of year, if
clouds break up sooner, or precipitation is heavier for longer into
the day, temperatures could be much warmer or cooler. But for now low
to mid 70s looks like a reasonable forecast at this point.

Active weather looks to persist through the end of the week and
right through Mother`s Day. The troughing over the western states
through the end of the work week will allow for persistent southerly
flow through the eastern Plains and lower Missouri Valley. This will
maintain ample moisture for convective development and it looks like
there is good chance for storms nearly every period from Thursday
onward. For Thursday, while shear looks relatively weak early on, it
should increase by the afternoon as stronger southwesterly flow
moves over the region. With CAPE building to perhaps as much 2000
J/kg during the afternoon, there appears to be some potential for
severe storms during the afternoon and evening hours. This trend
looks similar for Friday, although uncertainty begins to increase as
influences from the previous rounds of convection could play a role
in any subsequent convection (cloud cover, boundaries, etc.). The bottom
line is that, we remain in a favorable pattern for thunderstorm
development with varying degrees and combinations of instability and
shear. This adds uncertainty to the timing of and intensity of any
storms Friday and Saturday. But for late in the weekend and into
early next week, models show a good deal of consistency moving a
strong, negatively tilted upper trough into the Plains and developing
a strong surface low as a result. Synoptically, this looks like a
severe weather outbreak kind of pattern for the Central Plains given
the time of year. It`s still early and things could change but the
consistency in the models depicting the environment is impressive that
far into the future.

&&

.AVIATION...(For the 18Z TAFS through 18Z Wednesday Afternoon)
Issued at 1228 PM CDT TUE MAY 5 2015

Made some wholesale changes to this forecast. Most notably added a
VCTS group for this afternoon. Cumulus field on satellite, as well as
HRRR model guidance suggests a few scattered cells will be possible
across the area this afternoon. Tough call whether or not the
terminals will be directly affected, but there could be some
vicinity issues. Also, overnight added some wind gusts, per model guidance.
RAP sounding for the overnight period is a bit enigmatic with respect
to gusts reaching to surface due to diurnal decoupling, but would
suggest that if gusts don`t occur that a LLWS concern will develop
overnight, with winds around 40 kts about 800 feet off the surface.
Also added -SHRA group with VCTS for 15z Wed for rain showers
encroaching from the west.

J. Leighton

&&

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

$$

DISCUSSION...CDB
AVIATION...Leighton






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