IWX issues Area Forecast Discussion (AFD) at Aug 17, 12:40 PM EDT227
FXUS63 KIWX 171640
AFDIWX
Area Forecast Discussion
National Weather Service Northern Indiana
1240 PM EDT Sat Aug 17 2024
.KEY MESSAGES...
-There are chances for showers and a few thunderstorms this
weekend. Severe weather is not expected. Highs will be in the
mid 70s and low 80s. Lows will be in the upper 50s and 60s.
-Hazardous swimming conditions are expected on Lake Michigan
through Monday, with a moderate swim risk today becoming a
high swim risk Sunday into Monday night. A beach hazards
statement is in effect for Sunday into Monday night. High wave
action and life threatening currents are expected.
-Dry next week with partly to mostly clear skies. Highs will be
in low to mid 70s through Wednesday, then climb into the upper
70s and low to mid 80s for Thursday into the weekend.
&&
.DISCUSSION...
Issued at 511 AM EDT Sat Aug 17 2024
An upper low will settle overhead for this weekend, bringing chances
for showers and a few thunderstorms (non-severe) as we deal with
various waves rotating around the low. This morning we have a cold
front to our west (over Chicago) that will move through our forecast
area today, eventually providing a focus for precipitation chances
as we get further into daytime heating, in addition to some better
mid level lapse rates (around 6.0 C/km) and window of better bulk
effective shear (0-6 km around 20-30 knots). Expect scattered
showers this afternoon in addition to a few rumbles of thunder.
Highs will be in the mid to upper 70s and low 80s.
Gusty westerly winds today will cause waves on Lake Michigan to
build to 2 to 3 feet, with periods around 4-5 seconds. Breaking
waves and currents are expected. Have a moderate swim risk for both
Berrien, MI and La Porte, IN County beaches.
Shower and thunderstorm activity will dwindle outside of peak
heating tonight into early Sunday as the upper low continues it's
eastward progression. Expect shower activity to become more confined
to the lakeshore (some enhancement there with slight cold air
advection) and further east (along/east of I 69) as the last of the
shortwaves swing through our area. Greatest chances will be Sunday
afternoon when we can get around 200-600 J/kg sfc based CAPE and
perhaps some better mid level lapse rates (some models suggest this
is disjointed and more behind the front). Have chance/likely pops
for the Sunday afternoon and evening period, with potential for a
few thunderstorms.
Winds shift more north-northwest behind the front into Sunday night
and strengthen, with waves on Lake Michigan building closer to 4 to
9 feet. A beach hazards statement is in effect from Sunday into late
Monday night for the expected high wave action and resulting
dangerous currents (nearly direct approach and wave periods of 6 to
8 seconds). Those visiting the beaches should plan to stay out of
the water. A small craft advisory is also in effect for that period.
Monday into Saturday will be dry as an upper level ridge builds in
overhead. By Monday afternoon the expansive ridge will extend from
the desert southwest/Southern plains all the way up into the
Canadian Prairies, with surface high pressure encompassing the Upper
Great Lakes. This will slowly meander eastward and flatten through
next weekend as several shortwaves attempt to break it down on the
northeastern periphery. Expect cooler temperatures through
Wednesday, with highs in the low to mid 70s and lows in the 50s.
Thursday into the weekend temperatures rebound into the mid to upper
70s and low to mid 80s. Lows will climb into the upper 50s and low
to mid 60s.
&&
.AVIATION /18Z TAFS THROUGH 18Z SUNDAY/...
Issued at 1237 PM EDT Sat Aug 17 2024
A large area of low pressure centered over Lower Michigan is
bringing clouds and showers to much of the Great Lakes region
this afternoon. As this system slowly pivots through our area
over the weekend, scattered showers remain possible this
afternoon. Ceilings have fluctuated between 3-5 kft at the
terminals today, with the better chances for MVFR ceilings at
KSBN. Northwest winds could gust to 20 kts this afternoon.
Shower chances end this evening, and there may be a brief return
to VFR ceilings before more clouds move in overnight. By 06-09Z
Sunday, there is about a 40-50% chance of IFR ceilings down to
around 1000 ft. Additional chances for scattered showers arrive
Sunday afternoon.
&&
.IWX WATCHES/WARNINGS/ADVISORIES...
IN...Beach Hazards Statement from Sunday morning through late
Monday night for INZ103.
OH...None.
MI...Beach Hazards Statement from Sunday morning through late
Monday night for MIZ177-277.
MARINE...Small Craft Advisory from 11 AM Sunday to 5 AM EDT Tuesday for
LMZ043-046.
&&
$$
DISCUSSION...MCD
AVIATION...Johnson
Source:
IWX issues Area Forecast Discussion (AFD) at Aug 17, 12:40 PM EDT---------------
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