503 
FXUS63 KLSX 061547
AFDLSX

Area Forecast Discussion...Updated
National Weather Service Saint Louis MO
1047 AM CDT Sat Jul 6 2019

.UPDATE...
Issued at 1041 AM CDT Sat Jul 6 2019

Visibilities in central MO have been gradually improving over the
past few hours and the Dense Fog Advisory was allowed to expire. 
Upstream METARs and satellite observations suggest that the 
gradual improvement will continue this morning as the fog and 
stratus mixes out. 

Kanofsky

&&

.SHORT TERM...  (Through Late Tonight)
Issued at 322 AM CDT Sat Jul 6 2019

Patchy fog continues to reduce visibilities to less than a mile at 
times, but should improve after 13z Saturday.

Despite upper ridging aloft, a weak cold front over northern Iowa 
will continue to drift to the south today, moving into the forecast 
area after 12z Saturday. Some weak lift ahead of boundary combined 
with surface based CAPES in excess of 2500 J/kg and decent low level 
moisture, will see showers and thunderstorms develop especially 
during the afternoon hours. The best chances of rain will be over 
portions of northeast Missouri and west central/southwestern 
Illinois. Otherwise, another warm and humid day with highs in the 
mid 80s to low 90s with peak heat index values between 95 and 100 
this afternoon.

Showers and storms will tapering off by midnight as frontal boundary 
exits region and surface ridge builds in. Drier, less humid air 
will filter in with lows will be in the mid 60s to low 70s.

Byrd

.LONG TERM...  (Sunday through Friday)
Issued at 322 AM CDT Sat Jul 6 2019

(Sunday - Tuesday)

A similar pattern aloft to what we have seen the past several days 
will continue through early next week with upper level disturbances 
tracking around the periphery of an upper HIGH center to our south 
that will slowly retrograde westward across the south-central CONUS. 
The expected track of these disturbances on Sunday should edge the 
southern part of the forecast area in southern MO, and will 
correspond well to where the better moisture should be positioned 
with a surface front to our south.  Sufficient dry air in the column 
is expected to build in to justify removal of mentionable PoPs on 
Sunday save for a few areas in central and southeast MO. 

The surface front is already anticipated to buckle back to the north 
over the Plains on Monday and will push towards our region as a warm 
front late in the day.  This will allow mentionable PoPs to return 
to the area, albeit low ones.  Better chances for thunderstorms are 
expected on Tuesday when this warm front pushes through. 

Slightly below normal temperatures can be expected Sunday and Monday 
with the main surface front to our south, but should return to near 
normal or even slightly above normal by Tuesday.

(Wednesday - Friday)

At some point next week, the models continue to advertise the upper 
RIDGE center moving into the Rockies or High Plains and amplifying, 
resulting in NW flow aloft over our region.  This should easily 
allow a more significant front to push through at the start of the 
pattern change and deliver a period of cooler and drier weather. 
Models have come into a decent consensus on this beginning by late 
Wednesday.  The result should be another seasonably very warm day on 
Wednesday with below normal temps after, possibly carrying into the 
following weekend.

TES

&&

.AVIATION...  (For the 12z TAFs through 12z Sunday Morning)
Issued at 620 AM CDT Sat Jul 6 2019

Areas of dense fog, as well as IFR ceilings, over portions of 
central/northeast MO as well as west central IL will gradually 
improve by 14z Saturday. VFR flight conditions expected for the 
remainder of the forecast period outside of storms. Otherwise, light
and variable winds will become northwest to north as a cold front
slowly sinks south across the region today. 

SPECIFICS FOR KSTL: 
IFR ceilings over St. Louis metro area will gradually lift and
scatter out by 13z Saturday with VFR flight conditions expected 
for the remainder of the forecast period outside of storms. 
Otherwise, light and variable winds will become northwest to north
as a cold front slowly sinks south across the region today. 

Byrd

&&

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

$$

WFO LSX