Area Forecast Discussion
Issued by NWS St. Louis, MO

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FXUS63 KLSX 190808
AFDLSX

Area Forecast Discussion
National Weather Service Saint Louis MO
308 AM CDT MON SEP 19 2016

.SHORT TERM...  (Through Late This Afternoon)
Issued at 306 AM CDT Mon Sep 19 2016

Through sunrise...have issued a Dense Fog Advisory for the srn half
or so of the CWA. The areas most impacted will be low lying areas
and near water sources. However, counties across the ern portions of
the adv shud continue to see lower visbys as temps drop and moisture
pools along the sfc ridge axis. Further west, can not rule out fog
along rivers, but overall, should not be an issue.

Otherwise, not much change to the prev forecast for today. Fog
should burn off quickly with an otherwise clear sky. The sfc ridge
will continue to build ewd with winds becoming swly thru low levels
allowing a quick warm-up. Have continued to trend temps aoa the
warmer guidance.

The warm temps with somewhat good moisture return across wrn and nrn
portions of the CWA will allow CAPE values to jump above 2000 J/kg
by this afternoon. However, expect a strong cap to remain in place
and will delay convection across the area until at least this
evening.

Tilly

.LONG TERM...  (Tonight through Sunday)
Issued at 306 AM CDT Mon Sep 19 2016

Surface ridge moves off to the southeast by tonight with a weak cold
front approaching northern MO. Storms expected to develop along this
boundary, but just barely brush our northern counties as most of
energy and support will be to our north. Otherwise, clear to partly
cloudy skies expected with lows in the 60s.

By Tuesday, frontal boundary to weaken even more and wash out with
surface ridge building back in. So will will see dry and
unseasonably warm conditions for the rest of the work week. There is
a slight chance of activity to affect far northern portions of
forecast area, closer to surface boundary, Thursday and Thursday
night.

Then by the weekend will see increasing chances of storms as main
system approaches region. Extended models continue to slow down this
system, so backed off on pops for Saturday. Will see better chances
of storms for last half of weekend and into early next week. With
slower onset, will see warmer temps for Saturday, so raised them a
few degrees.

Byrd
&&

.AVIATION...  (For the 00z TAFs through 00z Monday Evening)
Issued at 623 PM CDT Sun Sep 18 2016

VFR through the period except for fog in river valleys overnight.
Similar to the last few nights, conditions remain favorable for
fog, and vsbys should fall to IFR after 06z and remain there for a
few hours. Fog will begin to mix out after sunrise and VFR
conditions are expected thereafter. Winds will remain AOB 10 kts
through the period.

Kanofsky
&&

.PRELIMINARY POINT TEMPS/POPS...
Saint Louis     89  68  89  70 /   0  10  10   0
Quincy          88  68  86  68 /  10  20   5   5
Columbia        88  67  87  68 /   0  10   5   5
Jefferson City  90  67  89  68 /   0  10   5   5
Salem           87  63  86  64 /   0   5  10   0
Farmington      87  63  88  64 /   0   5   5   0

&&

.LSX WATCHES/WARNINGS/ADVISORIES...
MO...Dense Fog Advisory until 9 AM CDT this morning for Crawford MO-
     Franklin MO-Iron MO-Jefferson MO-Madison MO-Reynolds MO-
     Saint Charles MO-Saint Francois MO-Saint Louis City MO-
     Saint Louis MO-Sainte Genevieve MO-Washington MO.

IL...Dense Fog Advisory until 9 AM CDT this morning for Bond IL-
     Clinton IL-Fayette IL-Madison IL-Marion IL-Monroe IL-
     Randolph IL-Saint Clair IL-Washington IL.

&&

$$
WFO LSX



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