Area Forecast Discussion
Issued by NWS St. Louis, MO

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FXUS63 KLSX 291228

Area Forecast Discussion...Updated Aviation
National Weather Service Saint Louis MO
728 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 12z TAFs through 12z Saturday Morning)
Issued at 641 AM CDT Fri Apr 29 2016

Upper lvl system over the 4 corners will eject ewrd this
aftn/evng. Ongoing convection across ern OK/wrn AR shud remain S
of the terminals thru the day tho the nthrn edge of this cluster
may come close to the STL metro sites as is passes. I delayed
onset of precip by 3-6 hrs. Overnight...beginning of precip may
be several hrs of --ra/sprinkles/widely scttrd --SHRAs. But
eventually more substantial SHRAs/TSTMs should dvlp and lift NE as
a warm front becomes aligned along US HWY 36 in MO and I72 in IL
by this evng. Occnl SHRAs/TSTMs are expected to continue until all
the activity lifts N Sat mrng. MVFR CIGs are expected to dvlp with
the heavier precip but flight conditions may become IFR in some of
the heavier cores.

Specifics for KSTL:

VFR fcst thru 00Z. I delayed onset of precip by several hrs tho
very light VFR rain may dvlp this evng. Tried to cover this threat
with a VCSH group. Precip will become more widespread after
midnight...and continue in at least an occnl fashion until lifting
N Sat mrng. CIGs are expected to be VFR tonight but flight
conditions may drop to IFR in some of the heavier rain tongiht.



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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