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

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FXUS63 KEAX 092215
AFDEAX

AREA FORECAST DISCUSSION
National Weather Service Kansas City/Pleasant Hill MO
415 PM CST Mon Jan 9 2017

.Discussion...
Issued at 314 PM CST MON JAN 9 2017

...Impactful winter storm increasingly possible this weekend...

Tonight - Tomorrow Night:

Wave ejecting out of the Rockies will allow for the development of
a weak surface low in the Plains, traversing across the area.
This system will allow for some light precip to possibly fall in
portions of the forecast area, primarily focused on the eastern
half to two-thirds. Given that available moisture will be
contained to the lowest portions of the atmosphere, it`ll likely
be in the form of drizzle. As for temps, they`ll likely remain
above freezing during the overnight hours (although it`ll be
rather close to the freezing mark along the IA border) so freezing
drizzle chances should be negligible. As the low progresses
northeastward tomorrow, precip chances will go with it, leaving
the area dry late tomorrow through early Wednesday. Winds tonight
will continue to increase as the pressure gradient tightens and
temperatures tomorrow will rise well into the 50s south of the
Missouri River and range from the 40s to lower 50s north of the
river.

Wednesday - Thursday:

Temperatures will continue to be on the increase Wednesday with
highs topping over 60 degrees for most locations south of the
Missouri River. As a cold front crosses the area late Wednesday,
precip chances will be on the increase, particularly in the
eastern portions of the forecast area where better moisture
availability and overall forcing exists. Despite surface temps
dropping behind the front overnight Wednesday, warm air aloft
doesn`t seemingly want to give up control so any precip that falls
could be in frozen form or freeze at the surface. While this
doesn`t look like the type of situation that will produce
significant impacts, thanks to currently lower end PoPs forecast
behind the front, it will still be worth watching a bit more
closely as this time approaches. Surface high pressure over the
northern Plains will move in, allowing for the precip to move out
by later in the day Thursday.

Friday - The Weekend:

This is the time frame that we`ll continue to watch very closely
and as the headline states, could be rather impactful for the
forecast area. While there is still notable variability in model
solutions this far out, the models have been coming into
increasingly better agreement with each other, with the ECMWF
continuing to remain consistent in its run-to-run solutions.
Increasing confidence exists on an elevated warm layer combining
with below freezing surface temps to create a messy situation for
much of, if not the entire, forecast area. The depth of this warm
layer is rather deep on model forecast soundings, providing a good
sense that freezing rain could very well be the predominant precip
type for at least the southern half to two-thirds of the forecast
area. It currently looks like a classic freezing rain setup on
said model soundings. Moisture looks to not be a limiting factor
as the GoMex opens up for business, thanks to ridging over the SE
U.S. allowing for an open stream of southerly to southwesterly
flow to bring its moisture into the local region. However, and
this is important to note and stress, especially for the latter
half of the weekend, this system is still 5+ days out so the
forecast has PLENTY of time to change. Can`t ignore the signals
though, such as the CIPS analogs, that the models are depicting a
setup similar to past ice storm events. Definitely stay tuned.

&&

.Aviation...(For the 12Z TAFS through 12Z Tuesday Morning)
Issued at 448 AM CST MON JAN 9 2017

VFR conditions to prevail much of the day today with gusty southwest
winds of 20-25 kts possible. Winds will not weaken much this evening
as a strong low pressure center passes to our north. Main items of
concern during the overnight will be possible LLWS conditions along
with lowering CIGS and reduced VSBYs. Quick look at area fcst
soundings shows unidirectional flow aloft, suggesting speed shear
alone will be the main factor. As such, have a LLWS mention with this
morning`s issuance. Latest model guidance also now backing off on
IFR mention overnight as gusty southwest winds will likely result in
enough mixing to prevent VSBYs and potentially CIGS, from falling
too far despite increasing low-level moisture. As a result...have
elected to back off ever so slightly in accordance with latest
guidance trends, however confidence decreases after the 0z time
frame.


&&

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

$$

Discussion...lg
Aviation...32



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