Area Forecast Discussion
Issued by NWS St. Louis, MO

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157
FXUS63 KLSX 300446
AFDLSX

Area Forecast Discussion...Updated Aviation
National Weather Service Saint Louis MO
1146 PM CDT FRI JUL 29 2016

.UPDATE...
Issued at 819 PM CDT Fri Jul 29 2016

Have updated for area of storms that are expected to continue
moving ESE this evening. The bulk of these storms shud be exiting
the CWA by 04z based on the RAP low level moisture convergence.
However, an isod shower/storm may linger, especially along the wrn
flank of the line.

&&

.SHORT TERM... (Through Saturday)
Issued at 245 PM CDT Fri Jul 29 2016

(Tonight)

Main area of consideration at this time for showers and storms
heading into early evening is what is now produced underneath upper
TROF digging in overhead.  Enough storms have formed and congealed
to our southwest for some organization to this convection, with any
threat from these storms being focused on short-term downburst wind
potential.  The area of concern for this will be southeast MO thru
sunset.  Some activity from this TROF may linger overnight but
should be few and far between and be restricted to a small portion
of southeast MO.

Otherwise, storms along the old frontal boundary have now exited
our CWA to the SE, and showers and storms to the north associated
with a surface TROF should remain to the north and are not expected
to drop sufficiently south to affect our region.

MOS min temps of mainly 60s with around 70 in STL heat island look
reasonable.

(Saturday)

The two main wx-makers from today will remain in play on Saturday
but probably not to the extent they were earlier.

The upper TROF axis will remain and may create enough lift in some
portions of the southern CWA to result in widely scattered showers
and storms again.  PoPs of 20-30% are forecast.

The surface TROF to our north will once again try to edge into our
northern CWA (mainly areas near central IL) and may result in a
small chance for a shower or storm in that area.

Otherwise, most areas should remain dry with max temps close to
average for late July, or a couple degrees higher than persistence,
with values in the mid to upper 80s.

Britt

.LONG TERM...  (Saturday night through Next Friday)
Issued at 245 PM CDT Fri Jul 29 2016

(Sunday and Monday)

NAM and GFS still appear similar in their handling of the upper
trough that will lift eastward out of the Midwest early next week.
One weak shortwave trough will move across the area on Sunday that
will cause the surface front to move slowly northeastward into
central and southeast Missouri by late in the day.  Upper high will
build over the Central Plains on Monday causing the upper flow to
become more northwesterly and the front to move farther to the
northeast.  This will cause the chance for showers and thunderstorms
to spread northeast across the area on by Monday.

Temperatures will stay in the 80s on Sunday, but likely warm into
the 90s by Monday over central Missouri as 850mb temperatures
climb to around 20C.

(Tuesday through Friday)

Global models are showing a similar evolution to the pattern mid to
late next week.  Shortwave trough will move southeast across the
area on Tuesday with an upper high centered over the Central Plains.
This will bring scattered showers and thunderstorms to the area.
Upper ridge will then build over the area Wednesday and Thursday
causing the front to lift northeastward. An upper trough will move
from the northern Plains into the Great Lakes late in the week
causing a cold front to move south into northern Missouri and
central Illinois by late Friday.  This will bring an increased
chance of showers and thunderstorms to Missouri and Illinois.

Temperatures will warm up into the lower-mid 90s with heat index
values exceeding 100 by the middle of next week given that 850mb
temperatures are expected to be around 22C and surface dewpoints
will be in the mid 70s.

Britt

&&

.AVIATION...  (For the 06z TAFs through 06z Saturday Night)
Issued at 1142 PM CDT Fri Jul 29 2016

Not a lot of change from the prev TAFs. Conditions still appear
set for at least some light fog developing overnight. Believe UIN
has the best chances for lower visbys overnight. Raising some
questions are the area of clouds across IA that continue to
dissipate as they move swd. Otherwise, expect winds to remain nwly
thru the period and light.

Tilly

&&

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

$$

WFO LSX



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