Area Forecast Discussion
Issued by NWS St. Louis, MO

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FXUS63 KLSX 152133
AFDLSX

Area Forecast Discussion
National Weather Service Saint Louis MO
333 PM CST Sun Jan 15 2017

.SHORT TERM...  (Through Late Monday Afternoon)
Issued at 326 PM CST Sun Jan 15 2017

Freezing line continuing to lift northward through region this
afternoon. So freezing rain slowly changing over to all rain from
south to north. Have expired/cancelled Ice Storm Warning and
replaced portions over northeast MO, west central IL with a Freezing
Rain Advisory til 6 pm. Any ice accumulation in this area will be
less than a tenth of an inch.

Otherwise, most locations to see a bit of a break from precipitation
til after 06z tonight. Main shortwave/trof over southwestern US to
lift northeastward towards area with increasing surface temps and
low level moisture. So precipitation chances to be on the increase
after 06z Monday. During the day on Monday, surface dewpts to rise
into the low 40s to low 50s, decent low level jet and MU capes
between 100 and 500 J/kg, so slight chance of thunderstorms, mainly
during the afternoon hours.

As for temperatures, with system lifting northeast towards region,
will see steady or increasing temperatures tonight. Decent WAA ahead
of system on Monday with highs in the low 40s to upper 50s, a good
10 to 15 degrees above normal for this time of year.

Byrd

.LONG TERM...  (Monday Night through Next Sunday)
Issued at 326 PM CST Sun Jan 15 2017

The models are in relatively good agreement with the large scale
features Monday night into early Tuesday with the upper low moving
from NW MO into the lower Great Lakes. The associated surface low
will follow a similar track with the southward trailing cold front
sweeping across the entire area Monday night, and located east of
the CWA by 12z Tuesday. Good deep large scale ascent will continue
to favor showers/rain through the warm sector ahead of the front
on Monday night, with weak instability supporting isolated
thunderstorms. Tuesday will be largely dominated by weak CAA in
the wake of the cold front and extensive post-frontal stratus.
Temperatures while cooler than Monday, will still be above
average. There is a secondary northern stream short wave trof
progged to dig from the northern Plains into the mid/upper MS
Valley in the Monday night-Tuesday Night time frame. The GFS is
the odd model out with a slower solution showing more digging, and
this could maintain clouds longer and even help generate some
spotty pcpn if correct. At this time it has been largely discounted.

By Wednesday, a low level WAA regime gets well underway and this
should promote well above average temps at least on Wednesday. The
models diverge during the later part of the week with the
evolution and northeast movement of the lagging southwestern U.S.
upper low/trof. Both the GFS and ECMWF are similar bringing this
lifting upper trof/low into the MS Valley in a negatively-tilted
fashion however differ by timing on the order of 18 hours, with
the ECWMF faster centered from late Wednesday night-Thursday
night. Regardless of timing, temps should be above average, its
just how much above average and then timing on the attendant
threat of showers and maybe thunder. In the wake of this system,
deep southwesterly flow will evolve into the weekend keeping above
average temps going strong.

&&

.AVIATION...  (For the 12z TAFs through 12z Monday Morning)
Issued at 528 AM CST Sun Jan 15 2017
IFR conditions expected at all TAF sites through this period.
Freezing rain will continue through at least mid morning at both
KCOU and KSTL metro TAF sites, with freezing rain possibly mixed
with sleet at the onset moving into KUIN by around 18Z. After 15Z
to 18Z, surface temps should warm at KCOU and KSTL TAF sites to
above freezing. Ceilings will likely lower at KUIN to IFR by
around 20Z. Winds will gradually veer to east southeast during the
day.


SPECIFICS FOR KSTL: IFR ceilings will persist through this TAF
period. Temperatures are hovering very near freezing and
observations from KSTL indicate light icing on elevated surfaces.
Freezing rain will continue through around 15Z when temperatures
finally rise above freezing. Precipitation should end by 00Z
Monday. Light northeast winds will veer to southeast by late
Sunday evening.

Browning

&&

.LSX WATCHES/WARNINGS/ADVISORIES...
MO...Freezing Rain Advisory until 6 PM CST this evening for Knox MO-
     Lewis MO-Marion MO-Shelby MO.

IL...Freezing Rain Advisory until 6 PM CST this evening for Adams IL-
     Brown IL.

&&

$$

WFO LSX


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