065
FXUS63 KLSX 261746
AFDLSX

Area Forecast Discussion...Updated Aviation
National Weather Service Saint Louis MO
1246 PM CDT Mon Jun 26 2017

.SHORT TERM...  (Through Late Tonight)
Issued at 216 AM CDT Mon Jun 26 2017

Shortwave and associated cloud cover/showers developing ahead of it
evident on satellite/regional radar this morning across the northern
Plains and upper Midwest.  This feature will move south and bring
scattered showers and isolated thunderstorms to the CWA today. Think
greatest coverage will be this afternoon when diurnal heating aids
convective development. Have gone on warmer side of guidance for
temperatures given yesterdays highs and sunshine expected this
morning.

Any lingering convection should diminish quickly this evening with
loss of daytime heating and the shortwave exiting the region.
Temperatures will once again cool into the 50s areawide.

Sieveking


.LONG TERM...  (Tuesday through Sunday)
Issued at 216 AM CDT Mon Jun 26 2017

Upper level ridge to build in on Tuesday, so will see one more dry
and cooler day before going back to more summer like conditions for
the rest of the forecast period.

By Wednesday, upper level flow becomes zonal with active period
moving in. Will see several rounds of storms from Wednesday
afternoon through the rest of the forecast period. However, it will
not be continuous rain. First system on Wednesday will slowly drag a
frontal boundary south into forecast area. With upper flow being
zonal, boundary to stall out and will have the potential for locally
heavy rainfall for areas along and north of Interstate 70 through
Friday. The best chances will be from Thursday afternoon through
Friday.

By the weekend, upper level trof builds in allowing system to
finally push through region. Will still have chances of showers and
storms though.

As for temperatures, will see them moderate from mid week on with
highs back in the mid to upper 80s. Then dip back down a bit below
normal for the weekend.

Byrd

&&

.AVIATION...  (For the 18z TAFs through 18z Tuesday Afternoon)
Issued at 1237 PM CDT Mon Jun 26 2017

Area of light rain will impact KCOU early this afternoon, but VFR
visibilities expected. This area of rain should continue to weaken
as it approaches the metro terminals later on this afternoon so
have no mention in TAFs for now. Cannot rule out some very light
rain or sprinkles however. Isolated showers and perhaps a few
thunderstorms should develop across IA/IL this afternoon and sag
southward. Could see these storms approach KUIN very late this
afternoon/early this evening, but coverage too low to mention in
TAF. Wind direction the next several hours will be problematic,
but predominant winds behind the secondary cold front will be
light out of the north/northwest early on tonight. Light/variable
winds are expected late tonight and early Tuesday with surface
high in close proximity to area. Will have to watch for fog
tonight with a clearing sky and calm or near calm winds. With lack
of widespread measurable rain however, believe any fog would be
isolated to river valleys. For that reason, will have to watch
KSUS and possibly KCPS for fog development tonight.


SPECIFICS FOR KSTL:

Area of light rain to the northwest should weaken as it
approaches. Cannot rule out very light rain or a sprinkle however.
Secondary cold front should move through dry late this evening
with light northwest winds. Later tonight, light/variable winds
are expected near surface high pressure center. This high will
slide eastward so winds to become light out of the southeast on
Tuesday.


Gosselin

&&

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

$$

WFO LSX