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Area Forecast Discussion (AFD)

Issued by Chicago, IL (LOT)

FXUS63 KLOT 232335

Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
635 PM CDT Fri Aug 23 2019

1220 PM CDT

Through Sunday...

Dry and cooler conditions will continue through Saturday, and 
generally for the weekend, though with plentiful sunshine.  

Inland clouds, with enhanced convergence in southern Wisconsin and 
northern Illinois and low coverage elsewhere, will shift inland 
and dissipate later this afternoon and evening. 

Otherwise, large surface high pressure over the upper Great lakes 
will slowly slide east this weekend, to be centered over New England 
by Sunday morning.  Conditions across the local area will be 
unseasonably cool and dry, with highs on Saturday in the middle to 
upper 70s and upper 70s to lower 80s for Sunday. Given the 
continental-polar origin of the associated air mass, dewpoints will 
also be relatively low, mainly in the middle 50s. Overall, this is 
expected to result in pleasant weather with ample sunshine across 
the area. As the high shifts and winds turn more solidly
southeast, the focus of higher waves will shift to the northeast 
Illinois shoreline. 



205 PM CDT

Sunday through Friday...

Surface high pressure is expected to shift over New England on
Sunday ahead of a developing storm system over the Plains. 
Pleasant weather is expected to continue Sunday, with highs into 
the upper 70s to around 80across the area. However, cloud cover 
will increase across the area Sunday night into Monday as moisture
increases across the area in association with the approach of a 
disturbance shifting eastward across the Lower Missouri Valley. 
This system could result in some light rain potential entering far
southern portions of the area as early as later Sunday night. 

On Monday a well defined mid/upper level trough is forecast to
dig in over the Upper Midwest. As it does so, an associated 
surface low will deepen late Monday and Monday night over western
Ontario. This will will then drive a cold front eastward across 
our area Monday night into early Tuesday morning. While there will
be some chances for showers and thunderstorms during the day on
Monday, the best chance for showers and thunderstorms looks to be
Monday night into very early Tuesday morning as the cold front
shifts across the area. Severe thunderstorms do not appear to be a
big issue with these storms, but some locally heavy rainfall will
be possible.

Any lingering showers should end quickly early Tuesday morning 
following the passage of this cold front. Dry and pleasant 
conditions should return to the area for midweek as a surface high
settles over the lower Missouri Valley. High temperatures are
likely to remain in the 70s through late week.

Overall, mainly dry conditions are expected mid to late week.
However, forecast guidance suggests that another cold front could
move over the area sometime later in the week, and this could 
result in a period of showers and storms. Since this is a week 
away, and timing is likely to chance, I have not strayed from the 
blended guidance during this period.



For the 00Z TAFs...

VFR conditions will prevail through the TAF cycle with continued
east to northeast winds. Winds will be strongest mid morning
through early evening, with some slackening of the winds at night.

- Izzi


IL...Beach Hazards Statement...ILZ006-ILZ014 until 4 AM Saturday.

IN...Beach Hazards Statement...INZ001-INZ002 until 4 AM Saturday.

LM...Small Craft Advisory...nearshore waters 
     until 4 AM Saturday.