IWX issues Area Forecast Discussion (AFD) at Oct 7, 3:34 AM EDT921
FXUS63 KIWX 070734
AFDIWX
Area Forecast Discussion
National Weather Service Northern Indiana
334 AM EDT Mon Oct 7 2024
.KEY MESSAGES...
* Dry weather pattern continues this week.
* Cooler, seasonable, temperatures to start the week, warming
back well into the 70s to near 80 by Friday and Saturday.
&&
.DISCUSSION...
Issued at 330 AM EDT Mon Oct 7 2024
Low level cold advection and synoptic upper level wave have
allowed stratocu to overspread the southern Great Lakes this
morning. Breaks in the stratocu have been experienced over the
past few hours across south central Lower Michigan with some low
level subsidence developing in the wake of mid/upper level
trough. Back across southwest Lower Michigan and NW Indiana,
some lake effect/enhancement to low clouds persists as lake-850
mb delta temps are in the 10 to 15 degree range this morning.
Moisture depth with these clouds appears to be very thin, and
some entrainment of drier low level air from the western Great
Lakes and eastward migration of core of low level thermal
trough should reduce these clouds toward daybreak. Some patchy
cirrus may spill over upstream upper ridge today, but mostly
sunny skies are expected. The position of the local area on
western fringe of low level thermal trough today should result
in seasonable temperatures in the mid-upper 60s, perhaps
approaching 70 across west central Indiana.
For tonight, another upper speed max is expected to dive
southward across the Upper Midwest/western Great Lakes with an
accompanying secondary weak low level trough. The bulk of low
level cold advection with this feature should remain across the
northern/eastern Great Lakes however, with a more neutral
temperature advection pattern across southern Great Lakes/Ohio
Valley as sfc anticyclone drops south across the Mid MS Valley.
This will provide a good radiational cooling setup with lows
expected to be in the low 40s most locations tonight.
For Tuesday and Wednesday, persistence forecast utilized with
just a slight moderation of low level temperatures each day as a
stable upper wave pattern develops across CONUS. A dry low level
airmass during this time will support fairly large diurnal
spreads and even a potential of temps to drop into mid-upper 30s
Tue-Wed nights across south central Lower MI.
Flow deamplification is expected to follow for Thursday and
Friday with bulk of medium range guidance depicting a more
active pattern of Pacific waves dampening the central CONUS
upper ridge. This evolution will allow warmer low level temps to
build in for Thursday-Saturday in advance of potential late
weekend frontal passage. A preceding westerly flow regime will
offer little to no opportunity for notable low level moisture
advection into the area which calls into question extent of
moisture quality with potential lake weekend frontal passage.
The nature of previous forecast/blended guidance will continue
to be utilized for late weekend/early next week with just slight
chance shower PoPs. Some higher confidence exists in a brief
shot of cooler air early next week, but feel that 00Z
deterministic GFS may be a bit on the aggressive side with this
cold advection. The majority of ensemble mean data suggests
strongest low level CAA and more amplification of upper trough
will occur across eastern Great lakes into northeast CONUS.
&&
.AVIATION /06Z TAFS THROUGH 06Z TUESDAY/...
Issued at 142 AM EDT Mon Oct 7 2024
Surface high pressure to our southwest continues to allow for
dryness across the area and for VFR conditions through the period.
Current low cloudiness in MI sinking southward appears to be
breaking up some, but may bring 4 to 5 kft CIGs to the terminals
overnight. A secondary front may pass through Monday
afternoon/evening, but that should just allow for scattered mid
level decks. Winds will continue to come out of the northwest
through the period. Could see a few gusts reach 18 or so kts
late in the evening behind the front, the low level jet is
fairly weak and low level lapse rates are not that strong even
that late in the day.
&&
.IWX WATCHES/WARNINGS/ADVISORIES...
IN...None.
OH...None.
MI...None.
MARINE...Small Craft Advisory until 5 PM EDT this afternoon for LMZ043-
046.
&&
$$
DISCUSSION...Marsili
AVIATION...Roller
Source:
IWX issues Area Forecast Discussion (AFD) at Oct 7, 3:34 AM EDT---------------
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