Area Forecast Discussion
Issued by NWS St. Louis, MO

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FXUS63 KLSX 171140
AFDLSX

Area Forecast Discussion...Updated
National Weather Service Saint Louis MO
640 AM CDT WED AUG 17 2016

.UPDATE...
Issued at 626 AM CDT Wed Aug 17 2016

Two quick updates for this morning. First, the visbys across SW
IL have dropped to one-quarter mile and stayed as-is for a little
while now. Have issued a dense fog adv for a few hours this
morning. While clouds may help the fog linger a little longer than
usual for this time of year, expect visbys to be well above one-
quarter mile by 900 am.

Thunderstorms have redeveloped within area of moisture convergence
across north central MO and are slowly moving ewd. Have added PoPs
across the nrn portions of the CWA. These storms are expected to
dissipate over the next few hours with the loss of the LLJ. So,
there is some question as to how far east these storms will
propagate before they dissipate. Some of the latest guidance
suggests that redevelopment will be possible late this afternoon
into the evening across the same region. However, uncertain how
much the cap, albeit fairly weak, will erode this afternoon,
especially given the low level WAA that guidance suggests. Have
held off making changes to this afternoon for now and will allow
the day shift to have another look at the latest data.

&&

.SHORT TERM...  (Through Late This Afternoon)
Issued at 318 AM CDT Wed Aug 17 2016

Weak surface ridge to remain in place today with lingering mid and
high clouds streaming northeast through forecast area. In the
meantime, convective debris from storms just northwest of forecast
area to stream in. So skies to slowly thin out with warmest temps
over central/northeast MO and west central IL where they will get
more sunshine. Highs will be in the upper 80s in this area with low
80s over southeast MO and southwestern IL.

On another note, patchy fog has developed over portions of
forecast area early this morning, so kept mention in through 14z.

Byrd

.LONG TERM...  (Tonight through Tuesday)
Issued at 318 AM CDT Wed Aug 17 2016

Dry weather to persist through Thursday night for the most part,
then as ridge moves to our east, southerly flow to return once
again. Will see increasing moisture and instability ahead of a
strong cold front. So storm chances on the increase Friday with best
chances Friday night and Saturday. Then precipitation chances wind
down for last half of weekend as cold front slides through exiting
region by Sunday morning.

Drier and colder weather to filter in late in the day on Sunday with
below normal temps expected for the last half of the weekend and
into early next week.

Byrd

&&

.AVIATION...  (For the 12z TAFs through 12z Thursday Morning)
Issued at 626 AM CDT Wed Aug 17 2016

Any fog that has formed will dissipate quickly this morning. Winds
will generally be sly and light. Can not rule out a TSRA impacting
UIN later this morning or late this afternoon into the early
evening hours. However, probability is too low to mention in TAF
attm. Redevelopment of fog is possible tonight, but expected to
remain east of terminals.

Tilly

&&

.PRELIMINARY POINT TEMPS/POPS...
Saint Louis     87  72  89  72 /   5   5  10  10
Quincy          88  70  90  70 /  20  10  10  10
Columbia        88  69  88  69 /  10   5  10  10
Jefferson City  88  69  89  70 /  10   5  10  10
Salem           83  69  86  70 /  10   5  10  10
Farmington      83  67  84  69 /   5   5  20  10

&&

.LSX WATCHES/WARNINGS/ADVISORIES...
MO...None.
IL...Dense Fog Advisory until 9 AM CDT this morning for Bond IL-
     Clinton IL-Fayette IL-Macoupin IL-Madison IL-Marion IL-
     Montgomery IL-Washington IL.

&&

$$

WFO LSX



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