009
FXUS63 KIWX 020421
AFDIWX

Area Forecast Discussion
National Weather Service Northern Indiana
1221 AM EDT Thu May 2 2024

.KEY MESSAGES...

* Warm temperatures continue with highs in the 70s for much of
  the period. 80s will be most possible south of US-30 on
  Thursday.

* An unsettled pattern keeps a mention of showers and
  thunderstorms in many of the upcoming days with Friday and
  Tuesday having the greatest chance.

&&

.DISCUSSION...
Issued at 255 PM EDT Wed May 1 2024

A cold front through this afternoon into the evening providing
a renewed push of cooler and drier air for this evening. As
such, cloudy skies will evaporate and gusty winds to 20 to 25
mph this afternoon are expected to relax this evening. Cool
temperatures come in this evening and overnight tonight, falling
to the upper 40s to mid 50s. However, the cold front settles
across the southern tier of our counties or just south of the
forecast area, which also helps to provide a bit of a floor for
overnight temperatures.

With the surface high pressure to our east, a warm advection pattern
takes over Thursday as yesterday`s cold front now pushing northward
as a warm front. 60F degree dew points make a return Thursday
morning and there is some upper support and marginal instability
around for showers, and maybe a thunderstorm most possible after
sunrise. Upper support diminishes during the morning, but the
developing instability still may be able to maintain any
thunderstorms. If there is any chance for severe storms, it would be
closer to the better shear associated with the warm front, but
that`s mainly for Lake MI-adjacent counties in our NW. DCAPE looks
to creep towards 900 J/kg behind the warm front through the day so
perhaps a gusty wind could be had with collapsing cores.

What appears to be our best and most widespread chance for showers
and perhaps a thunderstorm moves in late Thursday night through
Friday in conjunction with the arrival of a cold front. This wide
time frame is as a result of what appears to be the front stalling
to our west. Given its early arrival in the west, would tend to
downplay any thunder chance there. Areas east of IN-15 and probably
more like east of I-69 could see thunderstorms as long as debris
clouds remain out of the area. The GFS has much more debris clouds
and is, therefore, more suppressed with the instability in our
east. Some sporadic wind shear is modeled to exist over our
forecast area and with 1.5 in PWATs, perhaps a moisture loaded
wind burst could be had from some of the stronger thunderstorms.

For Saturday, it appears a wave of low pressure forms along the
stalled cold front/baroclinic boundary and rises north moving
through nearby the forecast area. The NAM/ECMWF camp contains much
more instability despite similar similar BUFKIT soundings with the
GFS. Will account for this with slight and chance PoPs. Model
differences creep again for Sunday with the GFS pushing the cold
front through Saturday night, but the ECMWF holds the front back
still. Because of this difference, the ECMWF is much more active
with Monday`s weather, whereas the GFS is dry.

Slightly better model agreement with a Tuesday system allows for yet
another chance for showers and storms. Some shear appears to be in
reach for storms to tap into allowing for another severe weather
chance, but this time, damaging wind gusts and perhaps some hail
will be the main threats. Thunderstorms will, once again be possible
on Wednesday with that cold front still stalled out nearby. Finally,
by Thursday, an interaction between an upper low over the Northern
Plains and another in eastern Canada allows for some vorticity to be
pushed southeastward through the area pushing the stalled cold front
through the area and allowing for a cool down.

Through this period, temperatures rising into the 70s will be common
with Sunday still being the warmest and with the best chance to see
80F degree highs. It is interesting that the ECMWF hangs onto 60F
degree dew points with its stalled out front nearby through much of
the period. Perhaps a brief break in that humidity arrives Monday.

&&

.AVIATION /06Z TAFS THROUGH 06Z FRIDAY/...
Issued at 1218 AM EDT Thu May 2 2024

VFR through the period with light/calm winds tonight increasing
out of the southeast during the day on Thursday. A warm front
does lift into northern IN late this afternoon/evening with non-
zero chances for widely scattered convection.

&&

.IWX WATCHES/WARNINGS/ADVISORIES...
IN...None.
OH...None.
MI...None.
MARINE...None.

&&

$$

DISCUSSION...Roller
AVIATION...Steinwedel