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

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445
FXUS63 KEAX 161736
AFDEAX

AREA FORECAST DISCUSSION
National Weather Service Kansas City/Pleasant Hill MO
1236 PM CDT Wed Aug 16 2017

.Mesoscale Discussion...
Issued at 1204 PM CDT WED AUG 16 2017

Trends continue to be monitored for renewed convection this
afternoon as long awaited surface cold front starts working
through the area. Latest GOES-16 imagery showing plenty of
clearing in the wake of this morning decaying MCS activity, and
increasing instability is expected this afternoon as a result.
Latest BUFKIT fcst soundings suggest anywhere between 2-3000 J/kg
of MLCAPE this afternoon, with increasing deep-layered shear also
expected as upstream trough axis begins moving further east
across the Central Plains. Furthermore, 7.34 GOES-16 water vapor
channel showing a stream of warmer brightness temps advecting
northeast towards our area, which appears to be indicative of
steepening lapse rates resulting from an elevated mixed-layer
plume (note 12z Amarillo, TX sounding). In any event, look for
convection to develop along the cold front around 21z, with
discrete cells initially leading to an isolated tornado threat
before activity congeals into a forward propagating MCS. After
this occurs, main threat will transition to a damaging wind threat
as the line continues moving through west-central and central
Missouri.

&&

.Discussion...
Issued at 353 AM CDT WED AUG 16 2017

The main concerns in the short term will be for the chance for
severe weather this evening into tonight. Also, heavy rain this
evening may allow for localized flash flooding to occur.

Early this morning a large complex of showers and thunderstorms is
moving across central and eastern Nebraska and northwestern Kansas.
These storms are developing north of a east-west surface boundary
that runs from northern Missouri into south central Nebraska and
back to northwestern Kansas where the low level jet is focused. A
cold front extends from a surface low in northwestern Kansas into
western Kansas where additional storms have developed. This cold
front will be the main player in the potential for severe weather
this evening. However, this morning, scattered warm air advection
showers and thunderstorms out ahead of the system will bring
precipitation to the area this morning into this afternoon. Although
there will be significant cloud cover this morning, models still
suggest that as the front approaches the forecast area this evening
moderate instability of around 2000J/Kg will be available, and 0-6KM
shear will be around 40kts. These parameters would be sufficient for
storms capable of damaging winds and large hail. These storms will
also be capable of very heavy rainfall with PWAT values between 2"-
2.5". Storms are not expected to train but they will be slow movers
which may lead to localized flash flooding. These storms are expect
to progress across the CWA tonight as the cold front will exit the
area by tomorrow morning.

Temperatures will be near normal again today with highs in the mid
to upper 80s however with dewpoints in the low to mid 70s, heat
index values will reach into the low to mid 90s. Behind the cold
front on Thursday, temperatures will be a couple degrees cooler
however, without any cold air advection behind the front, highs will
still reach the low to mid 80s. Tranquil conditions will continue
Thursday night into Friday as high pressure resides over the area.
However, Friday afternoon high pressure will shift east and we get a
return to southerly flow allowing to warm a couple degrees into the
mid 80s.

The next chance for precipitation will come Friday night as a upper
level trough digs from the northern Plains into the Midwest. This
will force another cold front through the area and bring the chance
for storms...potentially severe...to the area. The remainder of the
weekend then looks to remain dry with a warming trend as a upper
level ridge build over the southeastern and south central CONUS by
Sunday. Expect highs in the mid 80s Saturday and in the mid to upper
80s by Sunday.

&&

.Specifics for the Total Solar Eclipse on August 21st...
Issued at 628 AM CDT WED AUG 16 2017

Warm conditions look to continue into Mon 8/21 as a upper level
ridge remains entrenched over the south central and southeastern
CONUS. This will allow temperatures to reach into the upper 80s to
near 90. However, those highs continue to look like they may be
tempered by not just the sun disappearing but, by cloud cover and
(as it stands now) a slight chance for showers (20%). Models
continue to depict weak shortwaves rounding the upper level ridge
axis and moving into the area. What models do not agree on is the
timing and precise locations of these features. As has been
mentioned with previous forecast issuances, this forecast is still 6
days out and much can change between today and Monday.

&&

.Aviation...(For the 18Z TAFS through 18Z Thursday Afternoon)
Issued at 1236 PM CDT WED AUG 16 2017

Convection expected to initiate along a cold front later this
afternoon with impacts expected at all KC area terminals. Expect
activity to develop towards the 21-22z time frame, with storms
steadily moving east through the early evening hours. With any
activity that impacts terminals, expect brief IFR VSBYs due to
very heavy rainfall rates. Storms should be start clearing to the
east after 00-01z, with VFR conditions then expected through the
duration of the fcst cycle. Further north at STJ, a bit more
uncertainty exists as to whether storms will impact the airport,
but for now decided to play it safe until convective trends can be
established this afternoon. Winds out of the southeast between
5-10 kts will shift to the northwest later tonight after frontal
passage.

&&

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

$$

Mesoscale Discussion...32
Eclipse...73
Discussion...73
Aviation...32



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