Area Forecast Discussion
Issued by NWS St. Louis, MO

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FXUS63 KLSX 290817

Area Forecast Discussion
National Weather Service Saint Louis MO
317 AM CDT FRI APR 29 2016

.SHORT TERM...  (Through Late This Afternoon)
Issued at 315 AM CDT Fri Apr 29 2016

Mid and high clouds from next system already streaming across
forecast area early this morning. But with dry east flow at surface,
it will take some time for the moisture to return. Instability will
be marginal as well. So mainly showers and a few thunderstorms will
develop over southern/western Missouri and increase in coverage to
the northeast. Otherwise, temperatures will be near normal in the
low 60s to around 70 for highs.


.LONG TERM...  (Tonight through Thursday)
Issued at 315 AM CDT Fri Apr 29 2016

Models still have some placement issues with the area of low
pressure with the NAM further north than the GFS, and the ECMWF
somewhere in between. For now feel that warm front to develop and
lift north across forecast area tonight, stalling out along the
I70 corridor. Decent low level jet helping to bring in plenty of
moisture and will see elevated convection develop and track east
northeast across forecast area.

On Saturday, if system is further north we could see more of a
severe weather threat. With surface dewpts in the low to mid 60s,
will see surface based CAPES in excess of 2000 J/kg, but shear will
be weak. So SPC has placed areas along and south of I70 in a slight
risk for Saturday with the main threat being large hail.

All models are indicating closed upper level low to open up and lift
out late Saturday night and Sunday with rain coming to an end by
Sunday evening.

For the rest of the forecast period, it looks to be dry as a surface
ridge builds in. Will see some weak upper level shortwaves slide
across southern portions of the forecast area through this period,
but little in the way of precipitation is expected. Temperatures
will be a bit below normal on Monday, but expect highs in the low to
mid 70s by Wednesday and Thursday.


.AVIATION...  (For the 06z TAFs through 06z Friday Night)
Issued at 1101 PM CDT Thu Apr 28 2016

The low level cloudiness over UIN has been shifting slowly
northward this evening and may actually clear out of UIN, at
least briefly overnight. May have a period of MVFR cigs early
Friday morning at UIN. Further south, just high level cloudiness
will spread into the taf sites late tonight. VFR, low-mid level
cloudiness will move into COU and the St Louis metro area by
Friday afternoon as moisture spreads into the area ahead of an
approaching storm system in the southern Plains and north of a
warm front. Showers may move into COU and the St Louis metro area
as early as Friday afternoon, but more likely Friday evening. Cigs
and vsbys may lower into the MVFR category Friday evening with
these showers and as the low levels saturate. Weak northwest
surface winds will veer around to an easterly direction by Friday
afternoon as they gradually strengthen.

Specifics for KSTL: Light surface wind will gradually veer around
to an easterly direction and increase to around 8-10 kts Friday
afternoon. Just some high level clouds spreading into STL late
tonight and Friday morning, then the cloud ceiling will gradually
lower Friday afternoon and night as showers move into STL late
Friday afternoon or evening. Cigs and vsbys will lower into the
MVFR category Friday night.



Saint Louis     70  58  74  56 /  20  80  80  50
Quincy          66  52  64  49 /  10  70  80  50
Columbia        67  56  74  52 /  40  80  60  50
Jefferson City  69  58  76  54 /  40  80  60  50
Salem           69  57  72  57 /  10  80  80  50
Farmington      68  57  76  56 /  40  80  70  50



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