Area Forecast Discussion
Issued by NWS Springfield, MO

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FXUS63 KSGF 101740
AFDSGF

Area Forecast Discussion
National Weather Service Springfield MO
1140 AM CST Tue Jan 10 2017

...18z Aviation Update...

.SHORT TERM...(Today and tonight)
Issued at 301 AM CST Tue Jan 10 2017

The main forecast concern for today will be wind as surface low
pressure tracks from northeastern Kansas into the southern Great
Lakes. Pressure gradients have been slowly tightening across the
Ozarks which has resulted in portions of western Missouri and
southeastern Kansas reaching Wind Advisory criteria (sustained 30
mph or gusts to 45 mph) during the overnight hours.

As that low passes to our north, we expect the strong south to
southwest winds to continue this morning across the entire area.
Additionally, mixing potential will begin to increase which will
allow for increasing wind gust potential. Winds will shift to the
west and then northwest from west to east across the area this
afternoon behind a passing cold front. Winds should also diminish
just enough behind that front to allow the Wind Advisory to expire
at noon west of Highway 65. The advisory will continue through the
afternoon east of Highway 65.

In addition to the winds, we may see some patchy drizzle and
perhaps a shower as low level moisture continues to increase ahead
of that front. Temperatures today will be very mild with highs
over most areas reaching the lower to middle 60s. We do not think
any record highs are in jeopardy at this point.

Winds will then quickly diminish this evening with dry weather
expected overnight. Low temperatures should range from the upper
30s across central Missouri to the lower and possibly middle 40s
over southwestern Missouri.

.LONG TERM...(Wednesday through Monday)
Issued at 301 AM CST Tue Jan 10 2017

Southerly winds will then increase again on Wednesday as upper
level short wave energy induces height falls and developing low
pressure across the central High Plains. We may see a shower or
two develop on Wednesday as low level moisture begins to increase.
A slightly better shot at showers and perhaps even a few
thunderstorms will come from later Wednesday night into Thursday
morning as a strong cold front moves south through the region.

That cold front will then continue to march southward Thursday
night as Arctic high pressure builds southeast across the Dakotas.
Meanwhile, the upper level flow will remain southwesterly and
deepen as upper level low pressure dives south along the
California coast. This should result in at least weak isentropic
upglide along with increasing frontogenesis in the 850-700 mb
layer. We are therefore expecting a band of precipitation (perhaps
rather "thin" at first) to break out across northern Arkansas and
southern Missouri from later Thursday night into Friday morning.
By this time, atmospheric profiles should be supportive of
freezing rain/freezing drizzle. We will have to watch for some
convective elements which could introduce some sleet potential. We
will be able to get a better handle on precipitation placement and
type as we start getting some higher resolution model data for the
Thursday night/Friday morning period.

As we get into later Friday and this weekend, the overall setup is
still in question. Initially, the main focus will be on the
placement of that Arctic high. Global models almost always
struggle with low level temperature gradients in situations like
this as they "smooth" the gradient far too much. With that surface
front/trough likely located to the south of the Missouri Ozarks
along with northeast surface winds in place, we have gone on the
cold side regarding temperatures from Friday afternoon into
Saturday...and may still not be cold enough.

With synoptic scale lift also expected to increase starting later
Friday, we should see an overall expansion in precipitation. With
the aforementioned expectations for temperatures, this should
continue the threat for freezing rain over most areas with perhaps
the exception of far southern Missouri where temperatures may get
above freezing.

As that high then begins to drift off to the east and that upper
level low begins to swing out towards the Ozarks, we may then see
that surface front try and lift north from Saturday night into
Sunday. However, confidence in how this will play out is very low.
When this system clears out of the area also remains in question.
There is some consensus that the main upper level low may finally
drive through the region sometime later Monday or Monday night. We
will have to watch hydro concerns starting this weekend with the
prolonged precipitation potential.

Here is the bottom line regarding this storm system. We are
becoming increasingly confident in the late Thursday night into
Friday night time frame when it comes to freezing rain potential.
Ice accumulation amounts remain in question as smaller scale
details and ice accumulation efficiency are yet to be resolved.
Once we get into Saturday night and beyond, confidence starts to
decrease regarding how this system will evolve.

&&

.AVIATION...(For the 18Z TAFS through 18Z Wednesday afternoon)
Issued at 1127 AM CST Tue Jan 10 2017

Gusty winds will continue across the region. Winds should begin
to slowly level off around sunset. Before then, wind gusts well
over 30kts can be expected from time to time. A small band a
showers has developed between JLN and SGF this morning. This thin
line of showers will slide eastward with time and may clip the SGF
area.

Southerly winds will begin to increase once again on Wednesday
(though not as strong as today). There is a signal for low stratus
over BBG tomorrow morning. Kept this time MVFR. Otherwise, VFR
conditions can be expected.

&&

.SGF WATCHES/WARNINGS/ADVISORIES...
MO...Wind Advisory until 6 PM CST this evening for MOZ056>058-069>071-
     080>083-091-092-096>098-104>106.

     Wind Advisory until noon CST today for MOZ055-066>068-077>079-
     088>090-093>095-101>103.

KS...Wind Advisory until noon CST today for KSZ073-097-101.

&&

$$

SHORT TERM...Schaumann
LONG TERM...Schaumann
AVIATION...Frye



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