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003
FXUS63 KLOT 091721
AFDLOT

Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
1221 PM CDT Sun Jun 9 2024

.KEY MESSAGES...

- Northwest winds gusting 30-35 mph this afternoon.

- Cold front this evening with gusty northerly winds tonight and
  Monday along with building waves and dangerous swimming
  conditions for Lake Michigan beaches.

- A gradual warming trend is expected Tuesday onward with
  periodic thunderstorm chances mid-to-late week (20-40%).

&&

.DISCUSSION...
Issued at 155 AM CDT Sun Jun 9 2024

Through Monday:

With mainly clear skies and light winds, shallow ground fog has
develop in some areas early this morning. Low level winds are
expected to slowly increase through sunrise and this will likely
limit the fog potential early this morning.

Northwest winds will steadily increase this morning with gusts
into the 30-35 mph range this afternoon. These stronger winds
may begin to diminish some by late afternoon with increasing
clouds expected in the late afternoon and into the evening but
some gusts are likely to persist through sunset. High temps will
likely reach the upper 70s to around 80 most locations today.

A cold front will move south down Lake Michigan this afternoon
and arrive into northeast IL this evening, switching winds to
the north/northeast. Winds may increase into the 30-35 mph range
over southern Lake Michigan and remain at those speeds through
daybreak Monday morning, then only slowly diminish Monday.
These strong northerly winds will allow for high waves at Lake
Michigan beaches and create dangerous swimming conditions.

High temps on Monday will be well below normal, possibly only
reaching the upper 60s for many areas near the lake and perhaps
lower 70s further inland. cms


Monday Night through Saturday:

Short-wave ridging will move overhead heading into Tuesday with
the center of an expansive surface high pressure shifting east
of the area. This will turn winds back out of the southwest
ushering in a stretch of warm advective flow into the region
with high temperatures already warming back into the mid-upper
70s by Tuesday afternoon.

Beyond Tuesday the upper level pattern will feature
predominantly zonal flow across the northern Plains into the
Upper Midwest. This general pattern will continue the trend
toward warmer and more humid conditions along with the potential
for thunderstorms in the region. Confidence in timing and
placement of any potential shower/storm chances remains low
through the end of the week due to continued variability in
model timing of subtle waves moving within the upper flow and
any associated MCSs. At this range the best signal for storms in
our area exists during the Thursday afternoon/night timeframe.
Something to keep an eye on over the coming days!

Petr

&&

.AVIATION /18Z TAFS THROUGH 00Z TUESDAY/...
-- Changed Discussion --
Issued at 1221 PM CDT Sun Jun 9 2024

Forecast concerns for the terminals...

- Gusty northwest winds of 25-30 kts this afternoon

- Lowering ceilings with cold front this evening along with a
  northeast wind shift


West-northwest winds will continue to increase this afternoon
with gusts expected to top out in the 25-30 kt range. Though,
pockets of locally higher gusts in excess of 30 kts may occur if
deeper mixing is achieved. The gusts will begin to subside a
bit this evening as a cold front begins to drift out of
Wisconsin. While no precipitation is expected with the front,
ceilings will lower into the 2000 to 2500 ft range and persist
into the predawn hours Monday morning. Additionally, winds will
also turn northeasterly behind the front and remain breezy as
they do so. It should be noted that timing of the northeast wind
shift remains somewhat uncertain, but the general consensus is
that the wind shift should occur in the 01z to 03z timeframe.

Heading into Monday morning, winds will turn more northerly
around daybreak with speeds holding in the 10 to 14 kt range.
However, a lake breeze is expected to drift into the Chicago
terminals and turn winds back northeasterly around midday
(18-19z). Otherwise, expect ceilings to scatter to VFR
conditions Monday morning and remain as such through the rest of
the period.

Yack
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&&

.LOT WATCHES/WARNINGS/ADVISORIES...
-- Changed Discussion --
IL...Beach Hazards Statement from 9 PM CDT this evening through
     late Monday night for ILZ006-ILZ103-ILZ104.

IN...Beach Hazards Statement from 9 PM CDT this evening through
     late Monday night for INZ001-INZ002.

LM...Small Craft Advisory until 9 PM CDT Monday for the IL
     nearshore waters.

     Small Craft Advisory from 9 PM this evening to 9 PM CDT Monday
     for the IN nearshore waters.
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&&

$$

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