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

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902
FXUS63 KEAX 212332
AFDEAX

AREA FORECAST DISCUSSION
National Weather Service Kansas City/Pleasant Hill MO
532 PM CST Sun Jan 21 2018

.Discussion...
Issued at 319 PM CST SUN JAN 21 2018

A stout surface low is currently situated over central Kansas,
with a good push of warm southerly flow affecting east central
Kansas and west central Missouri. A pretty obvious quasi-
stationary warm front is located at the northern border of
Missouri, and is characterized by temperatures well in the 50s and
60s south of the boundary and temperatures in the 40s north of the
boundary. Expect the warm sector to be the region of some weak
thunderstorm activity as we go through the next 12 hours. In the
mid levels, there is a strong trough upstream of the forecast
area, which will approach through the next few hours. The
approach of this trough will help increase the coverage of some
scattered showers and thunderstorms later this afternoon.
Instability this afternoon will be somewhat limited, but still
relatively high considering the mid January date. MU CAPE of
around 500 J/kg can be expected later this evening and overnight
as the trough approaches and the cold air aloft associated with
the trough helps to steepen the mid level lapse rates. Surface
based activity does not appear all that likely with this activity,
as forecast soundings indicate a fairly thick layer of marginal
to weak instability, as the better lapse rates take hold of any
parcels around 5000 feet off the surface. The showers and
thunderstorms this evening could come in two rounds. The first
round would be in conjunction with a low level jet nosing into the
area, but with a slot of dry air aloft it may push the better
chances a little east of the KC Metro area. The second round of
thunderstorms would be in conjunction with some colder air aloft
arriving to the area, which would steepen mid level lapse rates
even more. This second round, indicated on the Hi-Res models might
be western Missouri`s (including the KC Metro area) best chance
for some thunderstorms. The first round would likely come through
around 00z, while the second round would be more in the 03z to 06z
time frame. Overall, not expecting this activity to be severe,
considering the minimal CAPE, but with good shear and good mid
level lapse rates it would not be out of the question to see a
strong storm or two after dark tonight.

The dry slot in the mid levels push the area clear of any
precipitation overnight as the main trough itself ejects through
the area. The prospects for winter weather become a little muddier
going into Monday/Tuesday. Virtually all models to this point have
been very pessimistic with respect to potential for winter weather
on the backside of the departing low pressure system. Consensus
model guidance also suggests surface temperatures much too warm
for any winter precipitation, which would relegate the backside
precipitation to mostly drizzle and rain. However latest model
guidance has suggest a slight southern shift in this system, which
may put far northern Missouri in better play for some light snow
during the day on Monday. While the KC metro area and the I-70
corridor still seem rather safe from much in the way of wintry
precipitation the next 12 hours or so will need to bear some
watching for another shift south of the system, and perhaps a
better chance for some light wintry precipitation for areas along
the I-70 corridor.

By Tuesday the system ejects out of the area, and a relatively
quiet week of weather ensues. Above normal temperatures are
expected, with a gradual increase in daily highs through at least
Friday, when highs are expected to be in the middle 50s. Mid level
pattern shows some ridging, which will help with the warm and fair
conditions. The next trough is expected to come through the area
next weekend with some light rain, and perhaps some light wintry
precipitation on the backside as it ejects out.

&&

.Aviation...(For the 00Z TAFS through 00Z Monday Evening)
Issued at 532 PM CST SUN JAN 21 2018

3500FT-4500FT cigs are movg ewd into the terminals this evening.
Light scattered showers and perhaps an isolated thunderstorm is
expected to develop in the VC of this terminals around 02Z with
MVFR cigs btn 2-3kft. These storms are expected to continue to
affect the terminals btn 02Z- 06Z. After 06Z, the area is expected
to move into a dry slot with conds drying out and cigs returning
to VFR conds. Tomorrow morning btn 10Z-13Z lgt drizzle will be
possible at the terminals as MVFR cigs/vis move back into the TAF
sites. Tomorrow as the main area of low pressure moves thru the
area another round of rain or perhaps a rain/snow mix will be
possible. However, temperatures and surfaces should remain warm
enough to keep runway conds good. Winds will be light out of the
south tonight before veering to the southwest tomorrow morning.
Late in the TAF pd a cold front will move thru the terminals
veering winds to the northwest while increasing to 12kt-18kt.

&&

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

$$

Discussion...Leighton
Aviation...73



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