Area Forecast Discussion
Issued by NWS St. Louis, MO

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FXUS63 KLSX 210458
AFDLSX

Area Forecast Discussion...Updated Aviation
National Weather Service Saint Louis MO
1158 PM CDT Thu Apr 20 2017

.SHORT TERM...  (Through Late Tonight)
Issued at 245 PM CDT Thu Apr 20 2017

Front currently making its way through the forecast area is
bringing some showers and thunderstorms to the southern counties.
The trend is for this activity to continue to move toward the ESE,
exiting the forecast area by this evening. Much of the area will
then see a bit of a dry period before more widespread precip
chances reemerge by tomorrow morning.

WFO LSX

.LONG TERM...  (Friday through Next Thursday)
Issued at 245 PM CDT Thu Apr 20 2017

General model consensus is for showers and thunderstorms to pick
back up tomorrow, with off and on chances culminating later in the
day Saturday as a low pressure system traverses through. Moderate
to locally heavy rainfall will be possible later tomorrow through
Saturday. The 12Z GFS and ECMWF agree on a southern MO track
while the Canadian takes the surface low on a much further south
track. Despite these spatial differences, overall model consensus
is for those periodic precip chances through Saturday night, upon
the low`s departure.

The forecast area will enter into a dry period for the latter half
of the weekend into the early part of next week. While there are
increasingly divergent model solutions for the next system
approaching/crossing the region by mid-week, long-term models
depict a front moving through with precip chances popping up along
and ahead of it. The ECMWF is the fastest of the three
aforementioned models with the Canadian the slowest; Tues. night
fropa, early Thur. morning fropa, respectively. Have elected to
lean more toward the slower solution(s) given the typical
tendencies.

WFO LSX

&&

.AVIATION...  (For the 06z TAFs through 06z Friday Night)
Issued at 1151 PM CDT Thu Apr 20 2017

High pressure will settle into the region tonight as the cold
front continues to move southward into AR and TN. VFR flight
conditions are expected at the terminals overnight and through the
day on Friday with mid and high clouds spreading across the region
overnight and into Friday morning and gradually lowering VFR cigs
on Friday afternoon. Still some question on the northern exent of
any precipitation on Friday. Most of it will be centered across
southern MO. I can`t rule out a few showers at KCOU or the St.
Louis terminals in the afternoon, but confidence is not high and
any such occurrence will still result in VFR flight conditions.
Rain will gradually spread north on Friday night and impact all
the terminals except KUIN.

SPECIFICS FOR KSTL:

High pressure will settle into the region tonight. VFR flight
conditions are expected and through the day on Friday with mid
and high clouds spreading across the region overnight and into
Friday morning and gradually lowering VFR cigs on Friday
afternoon. Still some question on the northern exent of any
precipitation on Friday. Most of it will be centered across
southern MO. I can`t rule out a few showers at KSTL, but
confidence is not high and any such occurrence will still result
in VFR flight conditions. Rain will gradually spread north on
Friday night and become continuous.

Glass

&&

.LSX WATCHES/WARNINGS/ADVISORIES...
MO...None.
IL...None.
&&

$$

WFO LSX



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