Sunday, July 22, 2018, 10:28 AM EDT
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Area Forecast Discussion
Valid At
Wed, Dec 31, 7:00pm EST
FXUS63 KLOT 212335

Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
635 PM CDT Sat Jul 21 2018

157 PM CDT

Through Sunday...

Isolated to scattered rain showers continue through Sunday as the 
low over Northern Indiana slowly shifts southeast. An isolated 
thunderstorm is possible this afternoon.  Areas west of a McHenry to 
Rensselaer, IN line may see an end to the rain late tonight, while 
areas closer to the lake will have a chance of showers.

Temperatures are climbing quickly when there are breaks in the 
clouds, so I raised high temps to the upper 70s to around 80 this 
afternoon. Temps will be cooler when the clouds roll back overhead.

Additional showers are possible Sunday as vorticity streamers rotate 
around the upper level low. I have higher confidence in scattered 
showers near and south of the lake Sunday. Isolated showers are 
possible inland especially if a strong vorticity streamer moves 
over northern IL.  Overall, my confidence is low in exact shower 
placement and timing, but expect dry hours. 

I left Sunday's forecast high temps alone since breaks in the clouds 
have led to warming the past two days. So expect mid to upper 70s 
when it's cloudy, but upper 70s to near 80 when the sun shines 



130 PM CDT

Sunday night through Saturday...

Mainly dry and quiet weather is expected to set up over the area 
for much of next week following the departure and weakening of the
upper low currently over the region. While the winds will 
generally be north-northwesterly, temperatures are expected to
warm back into the mid 80s (mainly inland from Lake Michigan) as 
the airmass over the region modifies and cloud cover clears across
the area. Onshore flow near the Lake Michigan shores will likely 
result in a bit cooler weather for areas along the immediate 

Later in the week a bit cooler weather looks to return to the
area, along with some chances for showers. This looks to occur as
model guidance forecasts an upper trough to begin to dig over the
Great Lakes Region by late week. 



For the 00Z TAFs...

635 pm...Forecast concerns include wind directions...ifr cigs 
tonight/Sunday morning and continued scattered showers.

Winds are generally northerly across the area early this evening.
Various outflow boundaries have allowed winds to shift to the
northwest and northeast at times. Wind directions may begin to
favor a north/northwest this evening but confidence remains low.
Wind directions are expected to shift back north/northeast Sunday
morning and then turn more to the northeast by late morning and
into Sunday afternoon. Speeds in the 10-15kt range with higher
gusts this evening and again Sunday. Speeds/gusts will diminish
quickly with sunset Sunday evening.

Cigs are generally vfr except near/over the lake. Guidance is in
good agreement with cigs lowering to ifr across northeast IL and
northwest IN later this evening and continuing into Sunday
morning. There will likely be some variability to the cigs but
trended into ifr given the model consensus. Some timing tweaks can
be expected. Cigs will lift through mvfr late Sunday morning/early
Sunday afternoon then to vfr later Sunday afternoon.

Scattered showers will be possible through early Sunday afternoon
across the entire area. The best times appear to be the next few
hours and then again overnight into Sunday morning. Changes to
precip timing are also possible as trends emerge. cms


157 PM CDT

Low pressure over Northern Indiana will gradually shift to the Ohio 
River by Sunday morning. Counter-clockwise flow around the low 
center will give way to 20-30 kt north to northeast winds across the 
lake through this evening. Small Craft Advisory will remain in 
effect through Sunday afternoon for all of the nearshore waters. 
Scattered showers and possibly a thunderstorm or two will continue 
through tonight. There is a slight chance for waterspouts through 
Sunday morning, particularly over the southern half of the lake. 
Winds will begin to gradually diminish through the day Sunday as 
high pressure builds into the Upper Midwest. Winds will become light 
Monday and Tuesday as the high shifts into the western Great



IL...Beach Hazards Statement...ILZ006-ILZ014 until 5 PM Sunday.

IN...Beach Hazards Statement...INZ001-INZ002 until 5 PM Sunday.

LM...Small Craft Advisory...nearshore waters until 5 PM Sunday.





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