673
FXUS63 KLOT 291905
AFDLOT

Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
205 PM CDT Wed May 29 2024

.KEY MESSAGES...

- Dry and pleasant weather is expected today through Friday as
  temperatures gradually warm.

- Periodic chances of showers and storms will return over the
  weekend into early next week.

&&

.DISCUSSION...
Issued at 205 PM CDT Wed May 29 2024

An upper level ridge will continue to build through Friday. As
it builds, better height rises and subsidence aloft will help
provide quieter weather through the short term. With onshore
flow expected each day (northeast today, becoming east
tomorrow, southeast Friday), plus diurnal heating, light
cumulus may develop each afternoon, but otherwise the sun should
have no issues shining through. Temperatures will steadily
climb from the 60s and low 70s today to the mid to upper 70s on
Friday, though cooler conditions can be expected along the lake
shore.

A short wave trough moves eastward out of the Plains late Friday
and into Saturday morning bringing rainy conditions back to
northern Illinois and northwestern Indiana. The GEFS model has
a comparatively stronger low at the surface that moves
northeastward over Illinois through Saturday, where the Euro
Ensemble has a weaker, less organized low moving toward
northwestern Indiana. Mid level lapse rates are not particularly
impressive and there will be a question to just how much
instability sufficient for thunderstorms can advect northward.
And while most models have the better chances for thunder more
confined to the track of the low, which may deviate in the next
48 hours, chances appear better near Chicago. With fairly weak
shear through the column, the primary expectation remains for
general thunderstorms, but if models start trending more toward
the GFS solution with a more northern track, perhaps a severe
risk can be re-evaluated. Lastly, models continue to trend the
timing slightly later and later where it may not arrive in
northwest Indiana until Saturday afternoon with lingering
showers trailing behind it.

Temperatures on Saturday will likely be kept in the middle 70s,
while low 80s are forecasted for Sunday. Both days look to be
noticeably cooler near the lakeshore, especially on the IL side.
Most of Sunday should be dry, but some models are spitting out
isolated pockets of rain during the day. Temperatures should
continue to warm into next week when we expect a return to the
80s for several days.

There has been a strong and consistent signal for a cold front
to pass through the region sometime between Monday and Monday
night with a favorable thermodynamic environment to support
thunderstorms building out ahead of it. The GEFS, CIPS, and CSU
severe prob guidance are all highlighting Monday for a potential
for severe weather in the region. A lot of that will be
dictated by the time of day that the front decides to move
through. A generally unsettled pattern will keep intermittent
rain chances in the forecast through midweek with another cold
frontal passage and thunder potential perhaps on the scope
around Wednesday.

DK/Doom

&&

.AVIATION /18Z TAFS THROUGH 00Z FRIDAY/...
Issued at 1222 PM CDT Wed May 29 2024

Satellite imagery shows some scattered cumulus across the area.
Meanwhile, satellite and radar imagery depict a boundary
pushing east towards the KORD and KMDW terminals with clear
skies behind the boundary. Winds will shift to northeasterly
behind the boundary by 18Z at KORD and KMDW, by 21Z at KDPA, and
by 00Z at KRFD. Winds will subside overnight to around 5 kts
with a shift back to a northwesterly direction. Another wind
shift will take place tomorrow morning with northeast winds at
5-10 kts expected through the day tomorrow. All TAF sites will
remain in VFR conditions through the end of the TAF period.

Carothers

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...Beach Hazards Statement until 10 PM CDT this evening for
     ILZ103-ILZ104.

IN...Beach Hazards Statement until 10 PM CDT this evening for
     INZ001-INZ002.

LM...Small Craft Advisory until 10 PM CDT this evening for Wilmette
     Harbor IL to Michigan City IN.

&&

$$

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