Area Forecast Discussion
Issued by NWS St. Louis, MO

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FXUS63 KLSX 030908
AFDLSX

Area Forecast Discussion
National Weather Service Saint Louis MO
408 AM CDT TUE MAY 3 2016

.SHORT TERM...  (Through Late This Afternoon)
Issued at 405 AM CDT Tue May 3 2016

In the short term, concern will be duration of fog that has
developed over portions of central MO. Cloud cover and slightly
drier air advecting into that region is complicating the forecast
and increasing the uncertainty as to how long any fog will persist.
Will go with a Dense Fog Adv thru about 13z for portions of central
MO and address changes as needed.

Otherwise, main concern today will be cloud cover, and therefore,
also temps today.

Mdls are in fairly good agreement with phasing of the upper trof and
pushing swd thru the area today. This shud be just enuf support to
generate isod SHRA again this afternoon. However, do not believe
that coverage will be as great as yesterday and shud be confined to
the srn third or so of the CWA. This same area will see much more
cloud cover than the remainder of the area.  Have therefore trended
aob the cooler guidance for today in these areas. Elsewhere, trended
twd a compromise.

Tilly

.LONG TERM...  (Tonight through Monday)
Issued at 405 AM CDT Tue May 3 2016

While upper level shortwave exits forecast area, secondary cold
front to approach region this evening. Will see activity continue to
fire up along the boundary, moving into northern portions of forecast
area by 04z Wednesday. Some decent instability, so would not be
surprised to see showers with some isolated thunderstorms as
activity sinks south tonight. Best chances will be along and east
of Mississippi River. Otherwise, it will be a bit milder with lows
in the mid 40s to low 50s.

On Wednesday, cold front to exit forecast area with some lingering
precipitation over eastern portions of forecast area. With northerly
flow over region, will see highs in the mid 60s to low 70s, just a
bit below normal.

Region dries out for remainder of work week as surface ridge builds
in. Temperatures to moderate, warming back up into the mid to upper
70s on Friday, then into the upper 70s to low 80s on Saturday.

No major changes to forecast for last half of weekend as next system
moves into the region. Showers and thunderstorms will be on the
increase Saturday night and persist through Monday.

Byrd
&&

.AVIATION...  (For the 06z TAFs through 06z Tuesday Night)
Issued at 1056 PM CDT Mon May 2 2016

Surface ridge was just northwest of our area this evening with
gradual clearing from the northwest. This clearing trend should
continue overnight at UIN and the St Louis metro area. Low stratus
and fog developed quickly at COU after the sky cleared out this
evening and this may happen at the other taf sites as well. The
stratus and fog will dissipate Tuesday morning followed by the
development of diurnal cumulus cloudiness, especially in COU and
the St Louis metro area with VFR conditions. Light surface wind
late tonight, then a west-northwest wind on Tuesday.  The low
level clouds will clear out Tuesday evening with the wind backing
around to a southwest direction.

Specifics for KSTL: VFR, low level cloud ceiling may gradually
clear out overnight with the development of stratus clouds and
fog towards morning. This stratus and fog will dissipate by late
Tuesday morning followed by the development of diurnal cumulus
clouds late Tuesday morning and afternoon in the VFR catagory.
These clouds should dissipate Tuesday evening. A light surface
wind late tonight will increase to around 7 kts from a northwest
direction Tuesday afternoon. The surface wind will back around to
a southwest direction Tuesday evening.

GKS
&&

.PRELIMINARY POINT TEMPS/POPS...
Saint Louis     67  53  66  46 /  20  20  10   0
Quincy          68  49  64  43 /  10  30   5   0
Columbia        67  50  67  44 /  10   5   5   0
Jefferson City  68  50  69  45 /  10   5   5   0
Salem           65  49  64  44 /  10  40  30   5
Farmington      63  46  67  43 /  20  10  10   0

&&

.LSX WATCHES/WARNINGS/ADVISORIES...
MO...Dense Fog Advisory until 9 AM CDT this morning for Boone MO-
     Callaway MO-Cole MO-Moniteau MO.

IL...None.
&&

$$
WFO LSX



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