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

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000
FXUS63 KEAX 232018
AFDEAX

AREA FORECAST DISCUSSION
National Weather Service Kansas City/Pleasant Hill MO
318 PM CDT Thu Mar 23 2017

.Discussion...
Issued at 318 PM CDT THU MAR 23 2017

For the rest of this afternoon, a few light rain showers or a
stray isolated storm are possible across far northwest Missouri,
and mainly quiet conditions are expected otherwise. Gusty south
winds are expected to continue as a strong LLJ develops this
evening; however, the weak inversion that sets up overnight may
be just enough to a void wind advisory criteria in our forecast
area.

Convection developing along the High Plains this evening is
expected to dissipate before reaching our forecast area Friday
morning, but a prefrontal trough may combine with isentropic lift
and increasing instability to support the development of showers
and embedded thunderstorms during the late morning hours Friday.
The trough axis may be east of the Kansas City area before firing
up, so have focused most PoPs with this round mainly east of the
MO/KS state line. At least some instability and around 40-50 kts
of deep layer shear may support elevated marginal supercell
structures with this first round, but expect it to be a lower-end
event as far as severe weather is concerned as storms will likely
be elevated and cloud cover will prevent surface-based instability
from building.

The main concern for tomorrow will be the potential for a second
round of storms to develop along the dryline/cold front in eastern
KS during the afternoon, and trek eastward into better moisture
and shear during the evening. Since the first round of convection
may develop east of KC, the environment may be a bit more primed
for robust convection. Models indicate up to 1500 J/kg of MUCAPE
by late afternoon, and deep layer shear will be very strong as the
stacked low shifts eastward. Since the low is so vertically well-
aligned, a thermal axis drawing up just ahead of the 850 hPa low
may weaken lapse rates just ahead of the surface low, and impede
updraft acceleration for surface-based parcels. In addition,
although deep layer shear is quite strong, winds are fairly uni-
directional, which keeps 0-1 km shear more on the order of 10-15
kts and the 0-3 km shear vector oriented nearly due north. Many of
the pieces for severe convection are in place, but with just a few
missing elements, feel that the severe threat is still somewhat
conditional for tomorrow. The highest risk for severe weather with
that second round will likely be in our western 2-3 rows of
counties, where instability will be strongest and storms will be
earlier in their genesis, then without the right shear orientation
to organize a defined MCS, morphology could become messy as
storms progress east.

Showers and perhaps an isolated storm will continue to fill in and
wrap around the surface low through at least part of the day on
Saturday, then drier air will move in behind for Sunday. Another
system is still expected to follow behind Sunday night and Monday,
but with a slightly further-south track to the surface low and a
modest moisture return, storms are not expected to be as robust.
A wetter pattern will continue through the rest of next week, but
have still decreased PoPs in the extended as it is still difficult
to nail down when and where any additional systems will track, and
do not want to "over promise" rainfall in areas that need it.
Although up to an inch of rainfall is possible with the rounds of
storms tomorrow through Saturday, the convective nature and the
speed of precipitation may prevent all areas from seeing that
much.


&&

.Aviation...(For the 18Z TAFS through 18Z Friday Afternoon)
Issued at 1233 PM CDT THU MAR 23 2017

Gusty south winds and VFR conditions will continue through the
next several hours, and while scattered cumulus may develop this
afternoon, bases should remain above 5,000 ft. Low-level wind
shear will be a concern tonight as winds between 1-2 kft begin to
increase to around 50 kts, and will continue until gusts begin to
translate to the surface after sunrise Friday. A few light rain
showers are possible across far northwest MO this afternoon and
across portions of central MO on Friday morning, but should stay
primarily north and then east of the terminals. Have added some
VCSH for Friday morning as showers develop, but again, expect
those showers to increase in coverage and intensity once they are
east of all terminals. Thunderstorms are possible just beyond the
end of the forecast period.


&&

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

$$

Discussion...Laflin
Aviation...Laflin



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