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

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FXUS63 KEAX 151931

National Weather Service Kansas City/Pleasant Hill MO
231 PM CDT Tue Aug 15 2017

Issued at 231 PM CDT TUE AUG 15 2017

A fairly active 24 hour period shaping up for the lower Missouri
Valley as at least 2 rounds of convection are possible before
through tomorrow evening. Starting things off, an unrelated area
of convection continues to churn through far south-central Iowa
this afternoon, with latest radar trends showing some spillage
over the state line into north-central Missouri. Fortunately, wind
fields aloft remain weak this afternoon and none of this activity
is expected to achieve severe limits. Regardless, pops have been
adjusted to account for latest radar trends for areas north of
Route 36. Further south, skies have cleared enough to allow temps
to warm into the middle to upper 80s under a fairly healthy veil
of diurnal cu.

Moisture return slatted to increase later tonight following the
passage of a weak frontal boundary that should begin moving
through around the 3z time frame. This feature combined with a
strengthening low-level jet will set the stage for redeveloping
convection during the predawn hours, as isentropic ascent along
the 295-305 theta surfaces increases over time. This activity
should have anywhere between 1000-1500 Joules of MUCAPE to work
with, however weak wind fields should preclude much in the way of
severe wx development. Latest model trends have delayed the
departure of this first round of convection Wednesday morning,
which leads to significant uncertainty for redeveloping convection
later in the day out ahead of the main cold front that is
expected to move through the region through the afternoon and
evening hours. Inspection of latest BUFKIT soundings seems to
verify this concern, with latest 12z guidance showing less
available instability that previous runs. Regardless, increasing
wind fields aloft will support a greater threat for severe weather
should enough instability develop to support robust updraft
development. Quick look at wind profiles shows a unidirectional
appearance, suggesting short line segments or splitting cells
would be possible with isolated strong wind gusts and marginally
severe hail. In short however, current day 2 SPC marginal risk
appears well suited given the cloud cover and instability
concerns mentioned above.

Precip to come to an end through Thurs morning as high pressure
begins sliding east from the Plains. This should lead to
seasonable temps with dry conditions persisting through Friday.
Cyclonic flow to become better established through Friday night
and the upcoming weekend as a large trough begins pushing east
through southern Canada. This will lead to renewed precip chances
by early Saturday morning as weak shortwave energy combines with
an incoming cold front to result in nocturnal MCS activity.
Unfortunately the active weather pattern looks to continue right
through the end of the forecast period as several rounds of
shwrs/storms will be possible through the middle portion of next
week. This could have implications for Monday`s eclipse viewing
and more details are provided below.


.Specifics for the Total Solar Eclipse on August 21st...
Issued at 231 PM CDT TUE AUG 15 2017

Forecast guidance this afternoon continues to hint at the
possibility of lingering convection across the Lwr Missouri Vly
on Monday, as energy moving across the northern U.S. suppresses
ridging to the American Southeast. Given this scenario if it were
to materialize, cloud cover would most certainly be possible
and/or likely across portions of area, with the highest
potential north of Interstate 70. It should be stressed however
that Monday still remains a sizable distance into the forecast
period and model fluctuations will undoubtedly occur between now
and then.


.Aviation...(For the 18Z TAFS through 18Z Wednesday Afternoon)
Issued at 1235 PM CDT TUE AUG 15 2017

VFR conditions expected this afternoon under an increasing veil
of fair wx cu centered between 3-4 kft. Winds this afternoon will
remain between 5-10 kts out of the south before weakening this
evening. Fcst models continue to highlight increasing chances for
precipitation in the form of shwrs/isolated storms after 06z as
the low-level jet interacts with a northward lifting warm front.
As such, all terminals will likely stand a chance of seeing
measurable precipitation before the bulk of activity exits to the
northeast between 12-15z. After this, expect several hours of dry
conditions before convection redevelops Wednesday afternoon as the
main cold front begins moving through the area.




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