Area Forecast Discussion
Issued by NWS St. Louis, MO

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FXUS63 KLSX 231957
AFDLSX

Area Forecast Discussion
National Weather Service Saint Louis MO
257 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.

GKS

.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.

Byrd
&&

.AVIATION...  (For the 18z TAFs through 18z Sunday Afternoon)
Issued at 1104 AM CDT Sat Apr 23 2016

Surface ridge extending from the Great Lakes region southwest
into eastern MO will shift eastward this period. The low level
cloudiness over eastern IA into northeast MO should remain north
of UIN this afternoon. The stratus cloudiness across southeast IL
should gradually dissipate this afternoon with daytime heating,
mixing and drying and remain east of the St Louis metro area.
There may be a few diurnal cumulus clouds at the taf sites this
afternoon. There will be a little high level cloudiness late
tonight and Sunday morning.  Southeasterly surface winds should
strengthen at UIN and COU through the forecast period as the
surface pressure gradient gradually tightens, becoming more
southerly on Sunday. Light northeast wind in the St Louis metro
area will also strengthen as well through the period, veering
around to a southeast direction by early this evening, then
southerly Sunday morning. There will be some LLWS conditions in
UIN and COU very late tonight and early Sunday morning as a
southwesterly low level jet translates eastward into northwest MO
with both speed and directional shear in the lowest 1000 feet.

Specifics for KSTL: Stratus clouds across southeast IL should
gradually dissipate this afternoon and remain east-southeast of
STL. Few diurnal cumulus clouds may develop this afternoon due to
daytime heating, then dissipate early this evening. There will be
some high level cloudiness late tonight and Sunday. Light
northeast wind will increase in speed to 8-10 kts by late this
afternoon or early this evening as it veers around to a southeast
direction. The surface wind will become southerly Sunday morning
and possibly gusty Sunday afternoon.

GKS
&&

.PRELIMINARY POINT TEMPS/POPS...
Saint Louis     55  82  63  81 /   0   0  20  30
Quincy          56  81  61  79 /   5   5  30  30
Columbia        57  81  60  78 /   5   5  20  30
Jefferson City  58  82  61  80 /   5   5  20  30
Salem           51  79  60  80 /   0   0  10  20
Farmington      52  79  60  79 /   0   0  10  20

&&

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

$$
WFO LSX



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