Area Forecast Discussion
Issued by NWS St. Louis, MO

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FXUS63 KLSX 240005

Area Forecast Discussion...Updated Aviation
National Weather Service Saint Louis MO
705 PM CDT SAT APR 23 2016

.SHORT TERM...  (Through Late Tonight)
Issued at 255 PM CDT Sat Apr 23 2016

Surface ridge extending from MI southwest into eastern MO will move
eastward.  The stratus clouds across southeast IL should continue to
dissipate late this afternoon.  Few-scattered diurnal cumulus
clouds, especially across parts of northeast and central MO will
dissipate early this evening with the loss of daytime heating.
Mainly just a little high level cloudiness tonight.  Lows tonight
will be warmer than the previous night, mainly due to southeast
surface winds on the backside of the surface ridge.  The warmest
temperatures will be across central MO with the coolest temperatures
in southwest IL.  Lows tonight will be about 5 to 10 degrees above
normal for late April.


.LONG TERM...  (Sunday through Next Saturday)
Issued at 255 PM CDT Sat Apr 23 2016

Dry and warmer weather to persist on Sunday, but will see an
increase in high clouds as next weather system approaches region.
With gusty south winds will see highs in the upper 70s to low 80s.

Sunday night rain chances to approach region, but models are a bit
slower with onset, so lowered pops just a bit. Then Monday through
Tuesday, frontal boundary to slowly slide south through area with
mainly scattered showers and thunderstorms. Front to stall out
across southern Missouri on Tuesday. Highs will be in the upper 70s
to low 80s on Monday, then dip down into the low 70s to low 80s
Tuesday and Wednesday.

Decent instability north of front Tuesday night, so could see
elevated activity develop and slide along boundary on nose of decent
low level jet. Large hail would be the main threat with this round
of storms.

Models are still indicating decent instability, CAPES in excess of
1500 J/kg and shear with system Wednesday afternoon, Wednesday night
as warm front lifts north through forecast area. All of this still
points to our first real potential severe weather day this spring,
but a lot can happen in 5 days. Stay tuned to further updates.

With everything a bit slower, main cold front to slide through early
on Thursday with precipitation tapering off to just slight chance
pops through Friday. Then extended models showing next system
lifting northeast towards forecast area Friday night and Saturday
with increasing chances of showers and thunderstorms once again.

Once system exits region on Thursday, will see precipitation taper
off. Even though it will be a bit cooler Thursday, highs will still
be a bit above normal in the mid 60s to upper 70s. Extended models
beginning to indicate another system approaching region on Friday,
but timing is hard to pin down. So for now kept slight chance pops.



.AVIATION...  (For the 00z TAFs through 00z Sunday Evening)
Issued at 650 PM CDT Sat Apr 23 2016

Dry and VFR conditions are expected at the terminals. There may be
some patchy fog late tonight and early Sunday over southern
Illinois and southeast Missouri. Low level wind shear is still
possible at KUIN and KCOU between 09-15Z as a 35-40kt low level
jet sets up between 1000-2000 feet. This threat will end by mid
morning as mixing begins and the surface winds begin to pick up.
Do expect some gusts above 20kts during the late morning and
afternoon hours.

Specifics for KSTL: Dry and VFR conditions are expected the next
30 hours. Southerly winds will increase after 18Z on Sunday
afternoon with wind gusts over 20kts.





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