620
FXUS63 KLOT 110538
AFDLOT

Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
1238 AM CDT Sun Aug 11 2024

.KEY MESSAGES...

- Dangerous swimming conditions persist into this evening,
  mainly at Lake Michigan beaches in and east of Porter county
  IN.

- The period will feature low humidity levels, seasonable to
  seasonably cool temperatures, and low (30% or less) chances
  for rain.

&&

.DISCUSSION...
Issued at 241 PM CDT Sat Aug 10 2024

Through Sunday night:

A seasonably cool airmass continues to be housed beneath a
persistent Great Lakes upper trough, which currently resides
along the southern periphery of a slow moving an upper low
across southern Ontario. Consequently, afternoon air
temperatures across our area today are only topping out in the
low to mid 70s. For reference, this is about 6 to 9 degrees
below our average highs in the low 80s this time of year. While
a weak disturbance across west central MN is expected to pass
across southern WI this evening, no precipitation it expected in
our area. In fact, we will actually see cloud cover and our
breezy northwest winds diminish through the evening as a large
surface high begins to settle in across the Mid-Mississippi
Valley. Efficient radiational cooling is this setup should thus
foster another very cool night for most areas. Overnight low
temperatures are forecast to bottom out generally in the low 50s
outside Chicago and away from the lake, though a few of the
coldest spots could fall into the upper 40s.

The weather on Sunday should be somewhat similar to that
experienced today, with the exception that the winds will be
lighter and temperatures will be a couple of degrees warmer.
Accordingly, high temperatures for Sunday will be in the upper
70s. Dry weather will continue Sunday, but eyes will be on the
next approaching weather disturbance that could produce a period
of rain showers across parts of the area on Monday.

KJB

Monday through Saturday:

No major chances were made this period from previous thinking
highlighted below.

Large scale pattern across the country through the upcoming work
week will generally feature modest ridging across the west and
with troughing to the east with Midwest in the middle with
generally west-northwest flow. Several shortwave troughs are
expected to ripple through the WNW flow bringing occasional
chances for some rain. Temperatures are expected to rebound back
close to seasonable norms.

First shortwave of interest is progged to move across the region
Monday. This wave will move across the region before Gulf
moisture will have had much of a chance to return north, with
what moisture/instability there is for it to work with likely to
lead to MCS development well to our south and southwest across
the Ozarks. Convection down in the Ozarks could further disrupt
northward moisture transport into our area, so while there could
be some scattered showers around Monday (especially
southwestern) CWA, rainfall should be spotty and on the lighter
end of the spectrum.

Dry weather is expected Tuesday and probably through Wednesday
as a transient and low amplitude shortwave ridge moves across
the area. The ridging should allow for temps to rebound back
into the low to mid 80s for highs.

Another shortwave is expected to bring shower and thunderstorm
chances back into the region late in the week, but confidence is
low with respect to timing and placement of best convective
chances. Given the lower confidence, opted to make no changes to
the chance pops offered up by the NBM Wednesday night through
Friday.

- Izzi/KJB

&&

.AVIATION /06Z TAFS THROUGH 12Z MONDAY/...
Issued at 1238 AM CDT Sun Aug 11 2024

VFR conditions are expected through this TAF forecast cycle.
West to west-northwest winds will pick up a bit this morning to
around 10kt. There will probably be a few sporadic gusts in the
upper teens late this morning into the afternoon, but
prevailing gustiness is unlikely. Winds will ease toward sunset.

- Izzi

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...None.
IN...None.
LM...None.

&&

$$

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