IWX issues Area Forecast Discussion (AFD) at May 10, 7:30 PM EDT868
FXUS63 KIWX 102330
AFDIWX
Area Forecast Discussion
National Weather Service Northern Indiana
730 PM EDT Sat May 10 2025
.KEY MESSAGES...
- Temperatures will be above to much above normal with highs around
75 to near 80 today through Wednesday.
- Chances for showers and thunderstorms replace our dry weather
beginning later Monday afternoon and continue through the
upcoming week. Thursday afternoon and evening has a chance for
severe weather.
&&
.DISCUSSION...
Issued at 234 PM EDT Sat May 10 2025
Surface high pressure and mid level ridging affects the area into
the first part of Monday providing dry conditions. One break in the
high pressure comes from a cold frontal passage that takes place
today, but given dry air it is expected to be a dry frontal passage.
The main thing this front is expected to do is increase wind gusts,
but the low level jet is relatively weak only reaching 25 kts at its
peak over Lake MI with around 20 kts just off Lake MI and into
southern Lower MI. 70 degree highs will once again be common on
Sunday as it was today.
With the aforementioned high pressure center now east of the region
on Monday and a trough entering the western US, a gap is opened up
to allow the ingredients/energy from a stalled upper low to our
south to move toward the region into Monday night. Dew points
between the 30s and 50s this weekend will now be securely into the
50s with 60s possible south of US-24. Given the antecedent dry air,
it may take some time to moisten the column until more like 3z
instead of around 21z. Models indicate better instability will be
around in the earlier the rain arrives with lesser chances by around
3z and depict this in the PoT Thunder grids.
The fringes of the energy from the upper low were reaching to the
area on Monday, but now, on Tuesday, the upper low center is just to
our south. So the area has bubbling instability and energy to work
with, but still lacks enough shear to provide a severe chance.
Scattered showers and storms will be possible especially during the
peak heating periods. Wednesday's setup is a similar to Tuesday's,
but perhaps a little bit warmer and more humid. Scattered showers
and storms will still be possible.
For Thursday, mid level ridging behind the now departing upper low
likely suppresses showers and storms Thursday morning, but another
trough is hot on its tails for Thursday afternoon and evening.
Given a low level jet out in front of a cold front arrives with
this trough, there is a better chance that shear will be around
increasing odds for severe weather. As always, we'll have to see
if instability is influenced by cloud cover, but the main
moisture axis moves through between 17z Thu and 7z Thu night.
So, locally heavy rain could be possible in this setup. An axis
of 7 C/km mid level lapse rates swings through that could help
hail formation and sustain convection into the night. DCAPE
comes in after 6z, which may be too late to be a factor and may
indicate more that dry comes in later in the overnight to lessen
severe weather chances, but still, cannot completely rule out a
damaging wind risk. SPC has highlighted our area in D6 Slight
risk for severe weather. 850 mb temperatures usually conducive
to 90 degree temperatures are right on our doorstep later
Thursday so we could make a run at the upper 80s to perhaps near
90 in spots before day's end.
Behind the cold front, Friday looks less humid with only 50 degree
dew points, but temperatures still look warm enough to get back into
the 80s with continued southwest flow. While Friday looks mostly
dry, one thing to watch will be a wave that circles around the upper
low that brought the severe chance Thu night. Models look to be
developing something convective in conjunction with this wave that
appears to emulate an MCS Friday night into Saturday. Depending on
where the cold front ends up after Thu night, it could still scrape
our south/southwest or it could stay south of us.
&&
.AVIATION /00Z TAFS THROUGH 00Z MONDAY/...
Issued at 725 PM EDT Sat May 10 2025
Surface cold front has cleared terminals early this evening with
some post-frontal northwest gusts to around 20 knots persisting
as of 23Z. Decoupling should result in loss of these gusts by or
shortly after 01Z this evening. Wind directions will gradually
veer to the northeast overnight as a broad ridge of high
pressure from the northern Great Lakes to James Bay area settles
across southeast Ontario Sunday morning. This will set up
easterly flow regime for Sunday with speeds generally around 10
knots. In terms of sky cover, few-sct high cirrus will lift
north at times into Sunday morning from the cut-off low to the
south, but VFR conditions should persist through this forecast
valid period.
&&
.IWX WATCHES/WARNINGS/ADVISORIES...
IN...None.
OH...None.
MI...None.
MARINE...Small Craft Advisory until 5 AM EDT Sunday for LMZ043-046.
&&
$$
DISCUSSION...Roller
AVIATION...Marsili
Source:
IWX issues Area Forecast Discussion (AFD) at May 10, 7:30 PM EDT---------------
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