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Today
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Partly cloudy in the morning, then becoming mostly cloudy. A slight chance of thunderstorms in the afternoon. Highs in the upper 70s. Southwest winds 10 to 20 mph with gusts up to 40 mph. Chance of precipitation 20 percent. |
Tonight
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Mostly cloudy. A chance of thunderstorms in the evening, then showers likely with a chance of thunderstorms after midnight. Unseasonably mild. Lows in the lower 60s. South winds 10 to 15 mph with gusts up to 30 mph. Chance of precipitation 70 percent. |
Sunday
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Mostly cloudy with a chance of showers with a slight chance of thunderstorms. Highs in the upper 70s. South winds 10 to 20 mph with gusts up to 30 mph. Chance of precipitation 50 percent. |
Sunday Night
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Showers likely with a slight chance of thunderstorms in the evening, then showers with a chance of thunderstorms after midnight. Unseasonably mild. Lows in the lower 60s. South winds 10 to 20 mph with gusts up to 30 mph. Chance of precipitation 80 percent. |
Monday
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Showers likely with a slight chance of thunderstorms in the morning, then showers likely with a chance of thunderstorms in the afternoon. Highs in the lower 70s. Southwest winds 10 to 20 mph with gusts up to 30 mph. Chance of precipitation 60 percent. |
Monday Night
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Mostly cloudy with a slight chance of thunderstorms in the evening, then mostly clear after midnight. Lows in the lower 50s. Chance of precipitation 20 percent. |
Tuesday
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Mostly sunny. Highs in the mid 70s. |
Tuesday Night
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Partly cloudy in the evening, then mostly cloudy with a chance of thunderstorms after midnight. Lows in the upper 50s. Chance of precipitation 30 percent. |
Wednesday
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Mostly cloudy. A chance of thunderstorms in the afternoon. Highs in the upper 70s. Chance of precipitation 30 percent. |
Wednesday Night
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Mostly cloudy with a 50 percent chance of thunderstorms. Lows in the upper 50s. |
Thursday
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Mostly cloudy. A chance of thunderstorms in the morning, then showers likely with a chance of thunderstorms in the afternoon. Highs in the mid 70s. Chance of precipitation 60 percent. |
Thursday Night
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Mostly cloudy with a 40 percent chance of thunderstorms. Lows in the lower 50s. |
Friday
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Mostly cloudy. Highs in the mid 60s. |
Forecast from NOAA-NWS
for 2 Miles SE Peotone, IL. (Zone forecast for Eastern Will)
000
FXUS63 KLOT 270852
AFDLOT
Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
352 AM CDT Sat Apr 27 2024
.KEY MESSAGES...
- Summer-like conditions today with high temperatures in the
upper 70s to low 80s and increased humidity levels.
- Breezy today with wind gusts as high as 40-45 mph possible
from mid-morning through the early afternoon.
- Isolated showers and thunderstorms expected to develop this
afternoon with coverage increasing markedly tonight. There
are lower-end chances for damaging wind gusts with this
evening`s storms and for localized flooding tonight.
- After a break Tuesday, an active weather pattern returns
midweek with multiple periods of showers/storms expected
through Friday.
&&
.DISCUSSION...
Issued at 352 AM CDT Sat Apr 27 2024
Through Sunday:
After any lingering overnight convection clears the area this
morning, the already breezy southerly winds will get even
breezier by mid-morning as we begin to tap into 40 kt flow in
the lower part of an overhead low-level jet. This will likely
translate to 40-45 mph gusts being observed during a brief window
of time between the mid-morning and early afternoon before the
magnitude of the gusts lessens a bit as the low-level jet
continues to gradually wane going into this afternoon. These
southerly/south-southwesterly winds will also serve to advect in
an unseasonably warm and moist air mass, characterized by
summer-like dew points in the low to mid 60s and temperatures
that will likely climb into the upper 70s to around 80F with the
assistance of some filtered sunshine.
Height rises, large-scale subsidence on the backside of the
departing upper-level trough, and the development of a capping
inversion should ensure that most of our forecast area will remain
dry through the daytime hours. However, by about the mid-afternoon,
the capping inversion will likely be eroded as a result of surface
heating, and some combination of broad isentropic ascent and low-
level confluence should help isolated to scattered convection to
sprout. Confidence is highest in this occurring in our southern
counties, where high resolution models continue to suggest that
there may be a zone of more focused ascent, but can`t entirely rule
out a stray shower/storm or two popping up elsewhere, so continue
to carry slight chance PoPs across the entire CWA during the
mid-late afternoon. There will be a plentiful amount of instability
around come this afternoon (MLCAPE of up to around 2500 J/kg), so
would not be surprised if a couple of storms managed to grow deep
enough to support a threat for downbursts and/or hail, but the
latest thinking is that the relatively broad and modest forcing
for ascent should preclude the development of any overly
rambunctious convection capable of making full use of the available
instability.
Meanwhile, to our west and southwest, a frontal zone is expected to
light up with convection during the afternoon and evening as large
scale forcing for ascent increases in advance of another upper-level
trough ejecting into the Great Plains. Convection that originates in
Iowa and Missouri is likely to grow upscale with time and track in
our general direction, with most of the latest CAM runs envisioning
that at least a semi-organized multicell storm cluster will be
knocking on the doorstep of our western CWA by mid-evening. While
these storms are expected to lose steam with time and eastward
extent, forecast soundings indicate that the degree of available
buoyancy here this evening could still be adequate to support the
development of new, deep updrafts along the storm cluster that
would carry a threat to produce strong to severe downburst winds,
particularly across our northwestern CWA. This threat largely
hinges upon this storm cluster developing a robust consolidated
cold pool that would be able to overcome increasing nocturnal
boundary layer stability, which does not appear to be a given at
this time.
Of additional interest with tonight`s thunderstorms is the potential
for localized flash flooding. It does not have the look of an ideal
flash flood setup by any means, but it does appear that storm
orientation could somewhat align with storm motion vectors for a
time and promote some potential for training convection. The
nose of a strong low-level jet to our southwest will also pivot
in our direction tonight and provide a continuous replenishment
of moisture into the region, which will likely keep thunderstorms
and heavy rainfall ongoing in at least part of our forecast
area throughout the night. Thus, some potential for localized
minor flooding does seem to exist in our forecast area tonight,
and WPC`s Marginal Risk in their Day 1 Excessive Rainfall
Outlook continues to look appropriate for highlighting this
possibility.
Shower and storm coverage is likely to diminish after daybreak on
Sunday as the low-level jet diurnally weakens. However, with surface
low pressure and an associated cold front still to our west, warm
conveyor belt showers and storms will likely continue in some
capacity in our forecast area during the day on Sunday, with
the highest chances for precipitation remaining across our
western counties through sunset.
Ogorek
Sunday Night through Friday:
Heading into Sunday evening upstream convection is likely
across Iowa and Missouri and pushing east of the Mississippi
River. This activity reaches the area by late evening. While
instability will be on a weakening trend, the arrival of better
forcing and a strengthening low-level jet would support a
localized damaging wind and large hail threat, especially west
of a McHenry to Kankakee, IL line.
A continued slower eastward progression of the surface cold
front will likely allow for showers to persist into the day on
Monday. Instability is much more muted compared to over the
weekend, though a few thunderstorms can`t be ruled out,
potentially lingering into the afternoon and early evening hours
east of I-57. Severe weather is not expected. Once showers exit
to the east late Monday, skies clear out as weak mid-level
ridging builds in allowing overnight lows Monday night to dip
back into the upper 40s to lower 50s. Tuesday will be noticeably
less humid as we remain between weather system. Ample sunshine
and a return to southwest flow will still allow temperatures to
warm well into the 70s again.
The break in the precipitation appears to be short lived as
ensemble guidance continues to support a return to an active
weather pattern midweek with multiple chances for showers and
thunderstorms Tuesday night through Friday as multiple
disturbances move within the broader northern stream quasi-zonal
upper jet.
Petr
&&
.AVIATION /06Z TAFS THROUGH 12Z SUNDAY/...
Issued at 1250 AM CDT Sat Apr 27 2024
Key Aviation Messages:
- Scattered SHRA with isolated TS early this morning
- SW wind gusts over 30kt expected after daybreak
- Periods of MVFR ceilings through the period
- SHRA/TSRA redevelops late evening through early Sunday AM
A narrow line of elevated convection will lift across the
Chicago area terminals near the start of the TAF period and are
accounted for with a TEMPO for TS from 6-7Z. Confidence in
whether additional showers/storms develop overnight remains on
the lower side, and accordingly opted to convert to a VCTS
mention through ~10Z to account for the back edge of a cluster
of storms west of Peoria that are lifting northeast toward the
area. Any lingering showers will diminish in coverage toward
daybreak.
Winds early this morning are breezy out of the southeast around
25kt with sporadic gusts near 30kt in the metro. Directions
will gradually veer S to SW with time overnight. More persistent
gusts in excess of 30kt are expected to develop after daybreak
and continue into the afternoon before easing toward sunset.
Additional isolated showers can`t be ruled out during the
afternoon, though confidence remains too low for a formal TAF
mention. Confidence does increase in showers developing by mid-
late evening along with the potential for embedded TS. The
timing for this period will continue to be refined with later
updates.
Petr
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...None.
IN...None.
LM...Small Craft Advisory until 10 PM CDT this evening for the IL
and IN nearshore waters.
&&
$$
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NWS LOT Office Area Forecast Discussion
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