Area Forecast Discussion
Issued by NWS Springfield, MO

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FXUS63 KSGF 270836

Area Forecast Discussion
National Weather Service Springfield MO
336 AM CDT Thu Apr 27 2017

...Significant Flooding Event Becoming Increasingly Likely...

.SHORT TERM...(Today and tonight)
Issued at 237 AM CDT Thu Apr 27 2017

A brief period of upper level short wave ridging will keep most of
today dry across the region. However, another short wave trough
will move east into the central Plains from later this afternoon
into tonight. This will result in increasing cloudiness with
showers developing and spreading east across the Missouri Ozarks
tonight. The best chance for showers will be from later this
evening into the overnight period as a low level jet stream
induces isentropic upglide. There may also be enough instability
for a few rumbles of thunder.

We went on the lower side of temperature guidance today with a
quicker increase in clouds expected. Most areas should warm into
the lower to middle 60s. Temperatures tonight should fall off in
the evening before steadying off overnight. Lows should be in the
lower to middle 50s.

.LONG TERM...(Friday through Wednesday)
Issued at 237 AM CDT Thu Apr 27 2017

A few showers or thunderstorms will remain possible into Friday as
that short wave energy shears off to the east. Attention then
turns to what will likely be a significant rainfall event for the
Friday night into Sunday time frame.

Upper level flow will become southwesterly with a low level
baroclinic zone sharpening up in a southwest to northeast fashion
from the Red River region, through the Missouri Ozarks, and
continuing into the Ohio Valley. Copious amounts of moisture will
be available with precipitable water value anomalies 2-3 standard
deviations above normal. Additionally, the presence of a nearly
continuous low level jet/moisture feed will result in regeneration
of convection for a long duration (versus a cold pool eventually
cutting off moisture).

Confidence in a flooding event has therefore become high enough to
post a Flash Flood Watch (will be out by 4 AM) for all of the
Missouri Ozarks and extreme Southeastern Kansas from Friday night
through Sunday. Widespread storm total amounts are still expected
to be in the 3-6" range, but with a caveat. With convective
elements in play for the duration of the event, locally higher
amounts are quite likely (in the 8" plus range). It is still a bit
early to nail down where the heaviest rain will fall.

Not to be outdone, the potential for severe storms will also be
present with this setup starting as early as Friday night. South
of that strengthening front, moderate amounts of instability will
be present with sufficient deep layer shear for strong to severe
storms. If supercells can develop, large hail to the size of golf
balls would be possible. The tornado threat will have to be
monitored as supercell motions would tend to parallel the front.
Even north of the front, elevated hailers will be possible.

The key to the severe potential Friday night will be where that
front sets up. The NAM has it draped across south-central Missouri
with the ECMWF a bit farther north. In contrast, the GFS keeps it
just south of the Arkansas border. We are leaning towards that
front at least making it as far north as southern Missouri. The
severe threat would then continue into Saturday, especially along
and south of where that front sets up.

The main upper level support for this system will then pull
through the region from Sunday into Sunday night. The main
shower/thunderstorm threat should begin to diminish later in the
day on Sunday, however some light wrap-around precipitation will
remain possible into Sunday night or even Monday.


.AVIATION...(For the 06Z TAFS through 06Z Thursday night)
Issued at 1144 PM CDT Wed Apr 26 2017

IFR to MVFR conditions will gradually give way to rising ceilings
overnight. VFR conditions are expected Thursday as surface high
pressure builds over the region.




SHORT TERM...Schaumann
LONG TERM...Schaumann
AVIATION...Foster is the U.S. government's official web portal to all federal, state and local government web resources and services.