442 
FXUS63 KLSX 152351
AFDLSX

Area Forecast Discussion...Updated Aviation
National Weather Service Saint Louis MO
651 PM CDT Fri May 15 2020

.SHORT TERM...  (Through Late Saturday Night)
Issued at 355 PM CDT Fri May 15 2020

Atmosphere remains rather stable over the region from the early
morning activity today. So focus shifts back to the stalled frontal 
boundary that is near the MO/AR border as of 20z. It will become a 
warm front and begin to slowly lift northward towards the forecast 
area late tonight. In the meantime, with light winds and plenty of 
low level moisture, could see some patchy fog develop, especially 
across portions of southeast Missouri. Added mention after 06z 
Saturday. Other issue is the chance for isolated showers and perhaps 
a clap of thunder, so kept slight/low chance pops along and south of 
I-70. 

On Saturday the warm front will slide northward through the region 
in response to the approaching upper level system from the west and 
backing flow aloft. Expect scattered showers and a few storms during 
the morning hours with this boundary, then focus then shifts to warm 
sector south of the warm front. ML CAPES between 500 and 1000 J/kg 
are expected by the afternoon with weak shear (around 10 to 15 kts), 
but still sufficient enough for isolated severe storms, mainly along 
and north of I-70 during the afternoon and evening hours. SPC has 
placed this area in a marginal risk with the main threats being 
large hail and damaging winds.

Saturday night, main cold front will begin to slide through region 
with showers and thunderstorms likely across the region.

Lows will be a bit above normal tonight in the mid 50s to mid 60s. 
Highs on Saturday will be warmer, in the mid 70s to low 80s, then 
lows Saturday night will be in the upper 50s to mid 60s.

Byrd

.LONG TERM...  (Sunday through Next Friday)
Issued at 355 PM CDT Fri May 15 2020

Showers and storms likely Sunday morning as cold front moves 
through. Then activity will taper off by early Sunday evening as 
surface ridge builds into region. So dry weather expected for the 
remainder of the forecast period. As for temperatures, the synoptic 
set up remains favorable for an omega block pattern that will keep 
the region in the northwest flow aloft, so temperatures will be near 
or slightly below normal through most of the work week, before 
temperatures begin to moderate once again.

Byrd

&&

.AVIATION...  (For the 00z TAFs through 00z Saturday Evening)
Issued at 646 PM CDT Fri May 15 2020

Dry and VFR conditions are expected through late tonight. Some fog
is expected to develop over southeast Missouri with MVFR or IFR
conditions. MVFR ceilings will develop at the terminals after 12Z
on Saturday morning, but rise above 3000FT by late morning.
Scattered showers and thunderstorms will move into the area during
the morning hours, and they will become more numerous during the
afternoon.

Britt

&&

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

$$

WFO LSX