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

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382
FXUS63 KEAX 260357
AFDEAX

AREA FORECAST DISCUSSION
National Weather Service Kansas City/Pleasant Hill MO
1057 PM CDT Tue Apr 25 2017

.Discussion...
Issued at 246 PM CDT TUE APR 25 2017

At 19z a surface low was located generally over northeast
Oklahoma with a strong pressure gradient over eastern Missouri,
producing stronger winds than what`s currently being experienced
across eastern Kansas and western Missouri closer to the low
pressure center. Behind this surface low is a cold front, which is
located along a line from KFNB to KAVK. This cold front will
continue to push eastward with time, ultimately being the focal
point for convective development later in the day. The warm sector
on the eastern side of the surface low will likely be characterized
by temperatures in the lower to middle 70s with dewpoints in the
lower to middle 50s as far north as Kansas City. Further south,
toward Bates County and areas of SE KS and SW MO dewpoints will be a
bit higher, but it`s doubtful that those dew points will make it far
enough north to bring instability high enough for robust/explosive
convection. That being said, there will likely be enough instability
- in the 750 to 1250 J/kg MLCAPE range - to produce a few storms,
which could be strong. Expect the bulk of the storms to form in
SE/EC Kansas, then move east through the evening and into the
overnight hours. Deep layer shear values will be in the 40 to 50 kt
range, but shear vectors will be generally parallel to the cold
front so storm mode could be more linear by the time it reaches the
forecast area. Ahead of the line of storms will be
southerly/southeasterly surface winds which will combine with the
veering-with-height wind profile to contribute to good low level
shear, which will make the tornado concern non-zero.  Mitigating
tornado risk will be the linear/quasi-linear storm mode as well as
temperatures cooling after dark. By 00z to 02z storms will be moving
into the KC metro area, then eventually off to the east into
central Missouri through the 03z to 05z time frame.

Post frontal showers with maybe a few thunderstorms will continue
through the day on Wednesday, more toward western and Central
Missouri, with areas of northwest Missouri likely staying mostly dry
through the day on Wed. By Wednesday night conditions will dry out
across the area, bringing a lull to the weather until late in the
week and into the weekend.

By Friday night troughing will take place over the western CONUS,
putting SW flow aloft over the forecast area. Good moisture will
return by this time period, which will provide some fuel for several
periods of showers and thunderstorms through the weekend. The major
focus for this activity looks like it will be mostly anchored to a
surface boundary which will likely set up in southern Missouri.
Expect the bulk of the precipitation to occur south of the forecast
area, however there will be plenty of precipitation across the
forecast area as the trough out west provides lift for the rain.
Still looking at a fairly tight gradient between areas of southern
Missouri where the heavy rain will be more widespread and areas of
northern Missouri where rain will be lighter with more lulls.
Generally expecting perhaps an inch or two along and north of I-70,
with areas south of I-70 perhaps getting over 2 inches through the
weekend. There could be some flooding concerns with this prolonged
rain event, but they should be somewhat isolated in areas much
further north than I-44.

&&

.Aviation...(For the 06Z TAFS through 06Z Wednesday Night)
Issued at 1056 PM CDT TUE APR 25 2017

MVFR ceilings are expected move into the area at the beginning of
the period with some isolated showers and embedded thunderstorms
moving through on the backside of a cold frontal boundary. The
precipitation is expected to move out of the area around 10Z about
the same time an area of IFR ceilings are expected to move into
the general area. Some upstream observations are showing IFR
conditions so a TEMPO from 10-13Z was added to show this trend.
Ceilings will start to slowly rise throughout the day becoming VFR
in the evening timeframe. Some guidance is showing a chance of
isolated showers and thunderstorms in the afternoon, but with the
amount of uncertainty in this happening it was left out of the
TAFs for now.

&&

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

$$

Discussion...Leighton
Aviation...CDB/Barham



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