Area Forecast Discussion
Issued by NWS Springfield, MO

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000
FXUS63 KSGF 211052
AFDSGF

Area Forecast Discussion
National Weather Service Springfield MO
552 AM CDT Sat Oct 21 2017

...12Z AVIATION UPDATE...

.SHORT TERM...(Today and tonight)
Issued at 300 AM CDT Sat Oct 21 2017

Steady south winds and mid level cloud cover were keeping temps
about 5-10 degrees warmer than this time last night. Most
locations were in the 60s and dont expect them to drop much
further. The region was on the eastern edge of a very strong
(60kt+) low level jet across the Central Plains. A few showers
will remain possible mainly across south central missouri Today.
An EML, as seen on water vapor, was located from western KS to
western TX moving east and will act to cap things off Today.
Therefore locations further west will likely remain dry, warm and
windy today ahead of the approaching storm system.

Setup/Ingredients: As a strong shortwave moves into the plains
this evening, a line of showers and thunderstorms will develop
across Eastern Kansas into Northern Oklahoma. Not much has
changed with the overall thinking on severe potential. While low
level moisture has continued to increase across the region,
overall moisture quality still has some work to do, as seen by the
LZK evening sounding. The OUN sounding looked better and this
airmass will continue to move north over the next 12-24hrs. Expect
60-65F dewpoints to arrive across the region by this evening.
Models have come into slightly better agreement on the instability
this evening. Overall 1000-2000j/kg of CAPE will be present for
the evening and early overnight hours with the NAM still the most
bullish however early runs of the RAP are coming in similar to
the NAM. Models are hinting at a slight uptick in instability
(including low level instability) during the 03z- 08Z timeframe,
this is somewhat concerning given that wind shear will also be
increasing as a 50kt low level jet develops. This uptick in
instability during the overnight appears to be tied to increasing
low level moisture directly ahead of the line of storms. This will
need to be monitored as it will have direct implications on storm
severity. 0-6km shear will be around 40kts with 0-3km shear will
be around 30kts. SRH will also be high given the southeast surface
wind component, therefore hodographs have a nice loop to them
during the overnight hours.

A general 1-2 inch rainfall is expected across the area. This may
cause a limited/marginal risk for flooding, mainly across SE
kansas into western Missouri. Most locations further east can
absorb the rainfall.

Timing: While some minor timing differences remain, Hi res models
are showing that line of storms entering our SE Kansas counties
between 7-10pm, likely reaching Joplin around 10pm or so. Then
progressing eastward, reaching the Springfield and US Highway 65
corridor in that 11pm- 1am timeframe. The storms will then move
east and slowly weaken, exiting the eastern ozarks by 5-6am.
Lingering showers will continue for most of the morning.

Hazards:Given ample instability and wind shear, we do expect the
storms to have severe potential for areas mainly along and west of
US Highway 65. Damaging winds are the main risk given strong wind
fields and linear structure. There will also be the potential for
isolated tornadoes that could develop within line segments that
surge to the northeast. While not a great setup for large hail,
steep lapse rates and lowering freezing levels due support a large
hail risk, mainly early on in the event.

Locations along and west of US Highway 65 need to pay attention to
forecast updates Today and Tonight on this severe weather threat.
The amount of instability Overnight will be critical in
determining the severity of storms.

.LONG TERM...(Sunday through Friday)
Issued at 300 AM CDT Sat Oct 21 2017

The shortwave trough will then get cut off from the mid level flow
and slowly move to our southeast Sunday into Monday. Showers will
be possible mainly across the Eastern Ozarks. A cooler airmass
will move in as well.

A strong trough will move down on Tuesday, reinforcing the cooler
conditions with highs in the 50s Tuesday. A brief warmup occurs
by Thursday then global models really diverge for the end of the
week into the weekend with regards to the mid level pattern.
Precipitation chances look very low for much of the upcoming week.

&&

.AVIATION...(For the 12Z TAFS through 12Z Sunday morning)
Issued at 546 AM CDT Sat Oct 21 2017

A stratus deck will move into the area this morning and MVFR
conditions are possible for a few hours during the morning into
early afternoon hours. Confidence is not very high regarding the
this stratus deck and when it will erode/mix out today. Winds
will be gusty out of the south all day with gusts of 25-30kts
possible. A line of showers and thunderstorms will develop tonight
to our west and push into the area after 02Z at JLN and after 05Z
at SGF and BBG. Ceilings will lower behind this line of storms as
well as winds switching to the northwest. IFR conditions are
possible by 12Z tomorrow morning with showers. Low level wind
shear is likely not only this morning but again tonight before the
front passes through.

&&

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

$$

SHORT TERM...Burchfield
LONG TERM...Burchfield
AVIATION...Burchfield


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