IWX issues Area Forecast Discussion (AFD) at Oct 29, 4:02 AM EDT635
FXUS63 KIWX 290802
AFDIWX
Area Forecast Discussion
National Weather Service Northern Indiana
402 AM EDT Tue Oct 29 2024
.KEY MESSAGES...
- Near record or record highs near 80 degrees expected on today
and Wednesday.
- Elevated fire danger Tuesday and Wednesday.
- Rain chances late Wednesday night into Thursday.
&&
.DISCUSSION...
Issued at 331 AM EDT Tue Oct 29 2024
A warm front continues moving east northeastward this morning, but
rain mainly stayed north of Indiana. Behind the warm front,
warm air continues streaming in as 850 mb temperatures warm from
the low teens Celsius to the mid to potentially upper teens
Celsius. Dew points are also able to eclipse the 50 degree mark.
It still appears that mixing will struggle today as mid level
cloud decks last into the early afternoon. Even still, wind
gusts will be able to surpass 30 kts (between 30 and 40 mph)
today, but may struggle attain 40 kts, and therefore stay below
advisory threshold. Some mixing may occur this afternoon enough
to allow a drop from the mid 50 dew points back towards 50
degrees. With all of this mind, MinRH values will be able to
stay in the 30 percent range today, especially for areas south
of US-30. Areas north of US-30 probably stay above 40 percent
MinRH. The data that we do have for 10 hr fuels are above
threshold, but the observation site is in some of our more moist
areas so there are probably other areas closer to threshold.
Given partner collaboration from the dayshift with lowered MinRH
criteria, have transitioned the Fire Weather Watch to a
warning.
Low level lapse rates today are forecast to achieve around
8C/km and there will be similar lapse rates forecast for
Wednesday. Mixing is slightly higher than today's and there are
pockets of 40 kts in the 850 mb jet, which makes a few gusts to
advisory strength winds possible on Wednesday. It appears that
less high level clouds may be around Wednesday afternoon, but
there could be better low level moisture that could cut into
mixing efficiency. All told, it could be a similar day to today
on Wednesday with highs right around 80 degrees again.
Between today and Thursday, a low pressure system across the western
CONUS undergoes a cyclonic wave break and cuts off from the upper
flow slowing the progression of energy from west to east.
Additionally, a vort max down at the base of the trough in Arizona
strengthens Wednesday and rises northeastward along the slowed front
towards the western Great Lakes. As it passes by to our northwest
late Wednesday night into Thursday, it pushes the cold front
eastward. It's moisture plume is able to push far north into Canada
and contains 2 to 4 SDs above normal PWATs owing to a very moist
column. However, quick storm motion and lacking instability
struggling to reach 300 J/kg of MUCAPE all contribute to lower
rainfall output. With the main low pressure system going northward
and the large scale ascent staying across our southern counties and
farther south, think the heavier rain largely splits the area. There
is still a 50 percent chance of 0.5 inch of rain along our Lake MI
adjacent counties as well as from White county to Jay county
Indiana. All other areas have a lower probability. One other aspect
of this front is that there may be just enough mixing to get gusts
up into the 30s of mph to mix down along it.
For Halloween/Trick or Treaters, it looks like gusty winds 25 to 35
mph will be possible during the morning and into the afternoon
before dissipating in the evening. Decorations may be lofted. Areas
west of I-69 have the greatest chance to have a rain free trick or
treat time.
Surface high pressure follows for Friday and Saturday. Behind the
cold front, a cold night with low temperatures back into the low to
mid 30s will be possible Friday night and high temperatures Friday
and Saturday will struggle to achieve 65 degrees.
It is a quick rebound though, as a deepening trough across the
western CONUS sees another wave break occur. This coupled with a
deepening ridge in the Gulf of Mexico sets up a stream of moisture
through the Plains States and towards the Great Lakes. There's still
some question on timing and location, but it looks to start Sunday
and probably continues at times into the next work week with the
potential for multiples waves to move northeastward along the
baroclinic zone.
&&
.AVIATION /06Z TAFS THROUGH 06Z WEDNESDAY/...
Issued at 153 AM EDT Tue Oct 29 2024
VFR conditions are expected at the TAF sites this period, with
winds gradually strengthening out of the south-southwest and
gusting to around 30-35 knots. Until then, we'll have
intermittent gusts and LLWS to contend with thanks to a warm
front to our southwest. Showers and thunderstorms with the LLJ
were moving just north of KSBN, so have VCSH for the next few
hours until the wave moves eastward tonight. Winds stay up
overnight and into Wednesday-with gusts around 25-30 knots
expected.
&&
.IWX WATCHES/WARNINGS/ADVISORIES...
IN...Red Flag Warning from 1 PM EDT /noon CDT/ this afternoon to 8
PM EDT /7 PM CDT/ this evening for INZ012>015-017-018-020-
022>027-032>034-116-203-216.
OH...None.
MI...None.
MARINE...Small Craft Advisory until 8 AM EDT this morning for LMZ043-
046.
Gale Warning from 8 AM this morning to 5 PM EDT Wednesday for
LMZ043-046.
&&
$$
DISCUSSION...Roller
AVIATION...MCD
Source:
IWX issues Area Forecast Discussion (AFD) at Oct 29, 4:02 AM EDT---------------
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