Area Forecast Discussion
Issued by NWS Springfield, MO

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FXUS63 KSGF 161741
AFDSGF

Area Forecast Discussion
National Weather Service Springfield MO
1241 PM CDT Wed Aug 16 2017

...Mesoscale Discussion and Update to Aviation...

.MESOSCALE DISCUSSION...
Issued at 1218 PM CDT Wed Aug 16 2017

Concerns have been increasing all morning regarding a flash
flooding risk across portions of western Missouri and southeastern
Kansas. Unfortunately, it appears that these concerns may be
playing out.

An east/west orientated outflow boundary has now nearly stalled
along, or just south of the Kansas/Oklahoma state line. This
boundary then curls in a northeasterly fashion into western
Missouri and extends from near Joplin to Osceola.

We are beginning to see training of thunderstorms from extreme
northeastern Oklahoma and southeastern Kansas into far
southwestern Missouri. This is occurring as a persistent low level
jet stream overrides the outflow boundary. Farther to the north,
convection from Stockton towards Truman lake is a bit more
progressive to the east given that low level shear vectors are
nearly perpendicular to the outflow.

As we head into the rest of this afternoon, it is quite possible
that regeneration of convection continues from northeastern
Oklahoma into western Missouri. Corfidi vectors remain very weak
across this region, thus the potential for training storms remains
high. Additionally, precipitable water values will remain around
2.00". Thus, we are looking at the potential for torrential
rainfall and flash flooding. This prompted the issuance of a Flash
Flood Watch for much of western Missouri and southeastern Kansas
through tonight.

The severe weather threat remains somewhat in question. A rogue
severe storm will be possible into this afternoon along and out
ahead of the outflow. However, deep layer shear rapidly decreases
the further east you go across the Ozarks.

We will have to watch for a severe storm threat later this evening
as redevelopment takes place along a frontal boundary across
central Kansas. This activity will likely develop into a line and
move southeast across the Missouri Ozarks from later this evening
into the overnight period. The expectation of this additional
convection was the reason for keeping the Flash Flood Watch going
through tonight.

&&

.SHORT TERM...(Today through Thursday)
Issued at 300 AM CDT Wed Aug 16 2017

Scattered showers/storms were slowly tracking northeast across the
area on the nose of a weak low level jet. Short term models continue
this trend through the morning hours, with mainly showers and
perhaps isolated thunder. A broad area of warm advection ahead of an
approaching cold front will produce lift for more scattered
convection this afternoon and evening as the cold front pushes
across central Kansas. Short term models are indicating an uptick in
intensity and coverage across eastern Kansas late this afternoon
and then push eastward. The biggest question will be how quickly
we can get some instability this afternoon. Still some
uncertainty regarding this but still feel confident we will see
stronger and possibly severe storms develop, with mainly hail and
damaging winds the main threat later this afternoon and evening.
At this point western and central Missouri and southeast Kansas
looks to have the better chances for any severe storms. With low
level and surface winds progged to remain south-southwest over the
area, the tornado potential at this point looks to be minimal.

Warm sector temperatures will push into the mid and upper 80s and
with dew points in the low to mid 70s will yield heat index readings
in the middle 90s.

Expect somewhat better coverage of showers/storms just ahead of the
front late this evening and overnight, but instability should be
waning by this time and severe weather threat also diminishing.
However, precipitable water values remain 1.5 to 2 inches, so
locally heavy rainfall will be likely with any of the storms ahead
of the front. The actual front does not push through until after 12Z.

Lingering showers Thursday morning will give way to quieter weather,
as high pressure builds for the afternoon and overnight hours.
Slightly cooler and less humid weather will settle in on Thursday,
but heat index readings will still manage to top off near 90.

.LONG TERM...(Friday through Tuesday)
Issued at 300 AM CDT Wed Aug 16 2017

Upper ridging begins to build across the inter-mountain west on
Friday, with both the GFS and ECMWF depicting a shortwave dropping
south out of the Dakota`s towards Missouri. Timing is somewhat of a
question, but it looks like showers/t-storm chances will ramp out
later Friday into Friday night and perhaps linger into Saturday.

For later in the weekend and into early next week 500mb heights rise
across southeast Kansas and the Missouri Ozarks. Cannot rule out
small rain chances during this time frame, but overall looks like a
dry period.

Temperatures look to be seasonal through the period, with a warming
trend late in the weekend and early next week as heights rise, where
heat index readings may push the century mark by Monday.

&&

.AVIATION...(For the 18Z TAFS through 18Z Thursday afternoon)
Issued at 1218 PM CDT Wed Aug 16 2017

Scattered to numerous showers and thunderstorms will continue from
this afternoon into tonight. These storms will produce torrential
rainfall, thus pilots should expected IFR visibilities with these
storms.

The storms will end from northwest to southeast across southern
Missouri late tonight. We may see a period of MVFR ceilings
develop from late tonight into early Thursday morning behind a
passing cold front.

Surface winds will remain southerly to southwesterly today outside
of thunderstorms, with gusty and erratic winds likely around
storms. Winds will then shift to the northwest late tonight behind
that front.

&&

.SGF WATCHES/WARNINGS/ADVISORIES...
MO...Flash Flood Watch through Thursday morning for MOZ066>068-
     077>080-088>091-093-094.

KS...Flash Flood Watch through Thursday morning for KSZ073-097-101.

&&

$$

MESOSCALE...Schaumann
SHORT TERM...Raberding
LONG TERM...Raberding
AVIATION...Schaumann



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