IWX issues Area Forecast Discussion (AFD) at Mar 13, 6:22 AM EDT469
FXUS63 KIWX 131022
AFDIWX
Area Forecast Discussion
National Weather Service Northern Indiana
622 AM EDT Thu Mar 13 2025
.KEY MESSAGES...
- The next 24 to 36 hours will be rather quiet, with much
warmer temperatures returning along with breezy conditions by
Friday.
- A period of showers and storms is expected overnight Friday.
While confidence remains low, there is potential for strong to
severe storms with locally damaging wind gusts west of I-69.
Outside of any storms, it will be breezy.
- Stronger winds are likely Saturday prior to the passage of a
strong cold front. A period of gusts to 45 mph or possibly
higher exists along with a risk for strong to severe storms
with locally damaging wind gusts east of I-69 Saturday evening
&&
.DISCUSSION...
Issued at 410 AM EDT Thu Mar 13 2025
Forecast fairly straight forward in the next 24 to 36 hours as an
increasing SW flow sets up to usher in warmer temperatures with
highs in the 70s still in store for Friday. We await the evolution
and eventual impacts of deep low pressure set to raise havoc for
many areas Friday afternoon into Saturday. Outside of the noted
issues below there are some fire weather related concerns that will
be addressed separately.
Forecast challenges are sandwiched in the Friday night to Saturday
evening time frame, with 2 potential windows of strong to severe
storms and a greater confidence wind event in the middle. Although
subtle strength and positions exist in the models, overall consensus
is for rapid cyclogenesis to take shape as a 120+ kt jet streak round
the base of the deep trough to the west with the stacked low
tracking from the general area of western KS at 18Z Fri to northern
WI at 18Z Sat. As this occurs, the LLJ will increase, peaking out at
70 to 80 kts Friday night in advance of a fast moving dry line that
will be accompanied by an area of steep mid level lapse rates and
plentiful shear/helicity. As has been discussed, these very dynamic
systems in the early spring can be huge troublemakers for our
forecast area with regards to QLCS development accompanied by
pockets of damaging winds and mesovort spin-ups. While these
concerns do exist, all signs continue to suggest the greatest threat
will reside back to our west and south (in the recently upgraded
moderate risk area) where greater instability and DCAPES exist with
lower level capping and lessing instability likely leading to a
decaying line as it enters our western counties maybe as early as 6Z
Sat. New DY2 maintained the slgt risk in SW counties with an
expansion of the marginal risk across the remainder of the area. If
the line can become established enough with some sort of cold pool
ti will stand a better chance of producing damaging winds gusts
across a larger area. However, the main concerns could only end up
for a few hours with a transition to more 40 to 50 mph gusts. By no
means should your attention be taken away from the potential as
while confidence is low, impacts could be high if this was to
maintain itself. Overall QPF/flood threat will be minimal given the
rapid speed and limited moisture.
Unlike the aformentioned severe weather concerns, much higher
confidence exists in a solid advisory level wind event across much
of the area Saturday as strong subsidence occurs in the wake of what
has transitioned to more of a pre-frontal trough with a stout low
level flow still in place. Models have been consistent on wind gusts
in the 35 to 40 kt range (translating to 40 to pushing maybe 50 mph)
mid morning in the afternoon. While the confidence is high, there
are some factors that could either enhance or limit the full
potential with some signals of sightly higher gust potential in NW
areas (maybe pushing 55 mph or so) and increasing cloud cover and
possible precip southeast (to be discussed in the next section).
Collaboration took place on a high wind watch with LOT/IND/ILX with
the majority leaning against a watch for now. Will continue with
increased messaging to highlight the concerns.
The final of the 3 concerns centers around the baroclinic zone that
will reside just southeast of out area with with low pressure set to
develop (convectively induced to some extent) and track into central
OH by 6Z Sun. A much better influx of gulf moisture will accompany
this feature with some of our SE counties possibly being grazed by
it. As the moisture arrives (as early as Saturday afternoon), the
same heating that will bring the stronger winds could also allow
temperature to warm nicely into the 70s with dewpoints in the mid
50s resulting in a narrow window of instability near or either side
of 00Z Sun. By far the greater severe chances will reside south
where a moderate risk exists across the AL/MS area but at least some
rain/embedded storms are possible. New DY3 outlook keeps a glancing
slgt risk near Lima, OH with marginal risk back to I-69 (similar to
thinking of the past couple of days).
While we will see a bit of a breather Sunday into Monday (including
a return to more seasonable temps), the rather energetic pattern
will persist with yet another deepening trough setting up for the
middle of next week (lots of differences on strength as expected)
with yet another (maybe somewhat weaker) wave on its heels.
&&
.AVIATION /12Z TAFS THROUGH 12Z FRIDAY/...
Issued at 621 AM EDT Thu Mar 13 2025
Dry air and VFR conditions remain with continued east winds
through the period. Winds may increase some during peak heating
time, but should remain at or below 10 kts so it won't require
another group.
&&
.FIRE WEATHER...
Issued at 414 AM EDT Thu Mar 13 2025
County fire officials have reported numerous grass and field
fires over the past several days as landowners and farmers take
advantage of the warmer weather. However, these same warm
temperatures, combined with afternoon relative humidity values
at or below 50 percent and most importantly periods of gusty
winds lead to unsafe conditions for burning. The concerns will
amplify further Friday into Saturday so wind gusts increase
further, possibly to 45 mph or higher by Saturday. Min RH
thresholds and 10 hour fuel levels are not expected to be met
with regards to red flag conditions, but this doesn't negate the
concerns for rapidly spreading fires, especially those not
attended or with proper precautions and extinguishing
techniques.
Even as winds subside and cooler temperatures return late in
the weekend, chances for wetting rainfall are not promising so
the overall dry conditions will persist.
&&
.IWX WATCHES/WARNINGS/ADVISORIES...
IN...None.
OH...None.
MI...None.
MARINE...None.
&&
$$
DISCUSSION...Fisher
AVIATION...Roller
FIRE WEATHER...Fisher
Source:
IWX issues Area Forecast Discussion (AFD) at Mar 13, 6:22 AM EDT---------------
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