355
FXUS63 KLOT 280607
AFDLOT

Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
107 AM CDT Fri Jun 28 2024

.KEY MESSAGES...

- Quiet conditions will persist into the overnight hours.

- A Marginal Risk for severe weather exists Friday over most of
  the area and southeast of Chicagoland on Saturday. While the
  threat isn`t particularly high-end, some gusty winds can`t be
  ruled out with any of the stronger storms.

&&

.UPDATE...
Issued at 905 PM CDT Thu Jun 27 2024

Mid level moisture continues to move in from the west and there
are some weak lobes of vorticity moving in out of ahead of a
shortwave in northwestern Iowa. This has resulted in some
returns developing on radar; however, dew points over
northeastern Illinois remain in the 40s to low 50s and the 00Z
KDVN sounding shows a pretty robust drier layer below 700 mb.
And while there was brief sprinkles reported in Dubuque about an
hour or so ago, the forecast was kept dry through the night.

Winds will be light and remain out of the east, before turning
to the southeast and eventually south late morning. Better warm
air and moisture advection will allow for PoPs to increase
through the morning but will really struggle with the drier air
in place as well as the limited forcing available. As such, the
PoPs were adjusted slightly to account for the eastward movement
of the wave, but were clipped to keep the chance (25 to 45
percent) for showers tomorrow morning west of the Fox Valley,
limiting the Chicago Metro area to only a slight chance. Model
CAPE is better far west of the area and does not start to
encroach into the forecast area until Friday evening at the
earliest, so thunder was kept out of the forecast through much
of Friday.

DK

&&

.DISCUSSION...
Issued at 244 PM CDT Thu Jun 27 2024

Through Friday Night:

Quiet conditions will persist into the overnight hours as a
moderately strong high pressure lingers over Lake
Ontario/Upstate New York. Warm advection will increase over the
Western Corn Belt tonight and isentropic upglide over an
approaching warm front will lead to showery precipitation over
Iowa tonight. Going into tomorrow, this rain will have to fight
some lingering low level dry air from the high pressure system,
but with time, the low levels will saturate and light rain
should spread in from the east and northeast with time, mainly
in the afternoon. CAPE with this activity is projecting to be
weak so widespread thunderstorms are not expected, but a few
rumbles of thunder may move through especially in the late
afternoon/early evening when models project a weak shortwave
moving through. There may be a bit of a lull around midnight,
before more showers and rumbles of thunder occur overnight as a
sfc front approaches from the northwest. There may be a bit
more elevated CAPE along the front. Any strong storms that occur
during this time period may have some gusty winds, but severe
weather chances attached the Marginal Risk look low.

NWS Chicago


Saturday through Thursday:

The sfc cold front is expected to slide southeast with time late
Saturday morning into the afternoon hours. As the front moves
through, dew points and temperatures should ease with time
leading to comfortable and cool conditions Saturday night into
Sunday. Comfortable and seasonable conditions are then expected
Sunday and Monday as high pressure exerts it`s influence over
the Upper Midwest.

An unsettled pattern is then projected to return Tuesday into
the rest of the extended as long-range models depict multiple
shortwaves and bouts of warm advection into late next week,
spurring daily chances for showers and thunderstorms.

NWS Chicago

&&

.AVIATION /06Z TAFS THROUGH 12Z SATURDAY/...
Issued at 1239 AM CDT Fri Jun 28 2024

Key Aviation Messages:

- ESE winds turn southeast by morning, then become breezy from
  the south-southwest by early afternoon.

- Scattered showers and sprinkles expected in the area by late
  morning/midday, most likely at KRFD with lower coverage
  farther east. TSRA chances appear minimal until late evening,
  and increase after midnight.

Multiple waves of showers will make their way toward the area
from the west through the TAF period, but for much of the
daytime hours will have some challenges overcoming dry low
level air. As winds turn more southerly and eventually southwest
by later in the evening and overnight, increasing low level
moisture will support better chances for showers and eventually
thunderstorms.

Lenning

&&

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

&&

$$

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