Area Forecast Discussion
Issued by NWS Northern Indiana

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000
FXUS63 KIWX 190724
AFDIWX

Area Forecast Discussion
National Weather Service Northern Indiana
324 AM EDT Tue Mar 19 2024

.KEY MESSAGES...

- Gusty winds between 30 and 40 mph are expected today with a
  few sporadic 45 mph gusts possible.

- Cold, below freezing overnight low temperatures are expected
  tonight through the weekend with the coldest lows occurring
  Wednesday and Saturday nights, when lows in the 20s are
  likely.

- The next chance for precipitation is later Thursday night
  through Friday with some combination of snow and rain
  possible.


&&

.DISCUSSION...
Issued at 316 AM EDT Tue Mar 19 2024

The trough and its attendant vorticity that brought the colder
temperatures Monday shifts east as surface high pressure noses into
the area from the south. Meanwhile, a second vort max passes through
the Northern Great Lakes today forcing a clipper system on a track
eastward to north. Plenty of low level dry air will keep any
precipitation at bay despite the passage of a cold front this
afternoon and evening. Warm air advection out in front of the cold
front will help warm temperatures back into the mid 40s to mid 50s
today and will also provide a low level inversion restricting
mixing. A 45 kt low level jet will slide through the area today
increasing wind gusts across the area. NAM bufkit soundings indicate
30-39 kt (35 to 44 mph) gusts could easily be brought down to the
surface with the occasional 40 kt (around 45 mph) gust possible. The
upper mixing threshold seems to reach 45 to 50 kts, which may allow
the cold front to bring down such winds. Am a little skeptical of
such an occurrence given the warm advection pattern we`re in. With
the dry air (30-40 percent MinRH values), warm temperatures,
and gusty winds, this is generally the first clue for fire
weather, however, the 10 hr fuels are still a little moist in
the 10-15 percent range as opposed to the single digits, which
would point to more sporadic grass fires if anything does get
going. With the aforementioned trough axis shifting eastward
today, 850 mb temperatures will be increasing overnight and the
boundary layer remains coupled enough to restrict radiational
cooling such that we bottom out in the low 30s to upper 20s as
opposed to the mid to upper 20s last night.

As is typical behind clipper systems, the surface high pressure
system following behind it noses in keeping the area dry Wednesday
and Thursday. The cold advection behind the clipper system helps
high temperatures fall back below seasonal norms to between the mid
30s and the mid 40s. Additionally, it will also help lows to fall to
the low 20s and upper teens Wednesday night It`ll take until
Thursday to relax the pressure gradient overhead as the high
pressure center approaches allowing 25 to 30 mph gusts Wednesday,
but sustained winds failing to exceed 10 kts on Thursday. Wednesday
may make another run at fire weather potential with the gusty winds
and dry weather (25 to 40 percent MinRH) along with drier 10 hr
fuels.

Chances for precipitation increase Thursday into Friday as a low
pressure system ejects off the Rockies. A setup where the energy for
this system actually goes to the north and the moisture plume stays
to the south is a possibility with this system, which may make for a
later start time and could cut out any snow mention at all. The GFS
seems to advertise such a solution, but it`s an outlier from the EC
and GEM solutions. It does look like warming takes place even on the
ECMWF despite precipitation occuring in its solution so rain may be
able to mix in during the day times. This looks to vacate the area
Friday night. We are currently advertising upper 30s to upper 40s
for highs Friday, but, again, depending on if it precipitates, could
see these dropping in future runs.

The weekend has begun to look drier as an upper low over eastern
Canada has trended southward slowing the advance of moisture out of
the Plains towards the region. Temperatures trend warmer through the
40s on Saturday to reaching 50 in our south Sunday. Models diverge,
next week, as it pertains to the sharpness of the trough ejecting
from the southwest. It could cause a low pressure system to ride
northward to the west of our region or it may graze our west.

&&

.AVIATION /06Z TAFS THROUGH 06Z WEDNESDAY/...
Issued at 1235 AM EDT Tue Mar 19 2024

VFR this period. Fast moving clipper skirting the nrn lakes will
yield a period of intense warm advection today with deep mixing
developing quickly this morning. Expect swrly winds will escalate
quickly after sunrise with peak gusts to 40kts or better this aftn.

&&

.IWX WATCHES/WARNINGS/ADVISORIES...
IN...None.
OH...None.
MI...None.
MARINE...Small Craft Advisory until 8 PM EDT this evening for LMZ043-
     046.

&&

$$

DISCUSSION...Roller
AVIATION...T


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