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000
FXUS63 KIWX 202341
AFDIWX

Area Forecast Discussion
National Weather Service Northern Indiana
741 PM EDT Sat Apr 20 2024

.KEY MESSAGES...

- Dry and cool this weekend with frost possible Sunday and Monday
  morning.

&&

.DISCUSSION...
Issued at 144 PM EDT Sat Apr 20 2024

Main forecast challenge this shift has been the frost potential
overnight tonight. The fly in the ointment is the temporal and
spatial coverage of mid level clouds associated with a weak
trough axis that will move through the area tonight through
Sunday morning. The cloud cover will keep low temperatures a few
degrees higher. Latest thinking is the western edge of the cloud
deck with the trough axis will begin to erode eastward just
before daybreak which does leave a small amount of time for
increased radiational cooling to occur. Dew points will be in
the mid 20s which usually does not bode well for frost to form,
however with still fairly moist soils from recent rains there
should be a jacket of higher moisture close to the surface which
would increase chances for frost deposition/formation. The best
chances of frost potential looks to be our far northeast IN and
most northwest OH counties along with Hillside, Branch, and St.
Joseph MI counties. However, confidence is low due to the above
stated reasons. Therefore, we have opted to use a Special
Weather Statement across the CWA to address the frost risk. Be
sure to play it safe and protect your cold sensitive plants and
animals tonight. Lows from 30 to 37 degrees are expected
tonight. Highs on Sunday will top out around the mid

With an upper level ridge axis beginning to move into the
region on Sunday, skies will clear out. This will allow for
decent radiational cooling however the synoptic warming with
the ridging should allow for low temperatures on Monday to be a
few degrees warmer than the Sunday morning lows. Lows of 32 to
39 degrees expected. However, some patchy frost would not be out
of the question. Monday`s high temperatures will rebound nicely
and highs in the low to mid 60s forecasted.

As expected, due to the blocky pattern, there has been a slight
push back in timing on the next expected trough arrival now
into Tuesday morning. Less than .20 inches of precipitation for
most areas with that impulse. Perhaps a thunderstorm or two will
be possible Tuesday afternoon/evening. Highs in the lower 60s.
Slight cooling will arrive in the wake of the trough passage
and in a more zonal pattern ahead of upper midwest ridging that
will move eastward into the region by Thursday. Wednesday highs
in the 50s. Thursday morning we will have to watch as with good
radiational cooling conditions in place lows in the low to mid
30s could increase the risk for frost once again. Building ridge
then allows for further warming with highs on Thursday and
Friday in the 60s with continued dry weather conditions.

&&

.AVIATION /00Z TAFS THROUGH 00Z MONDAY/...
Issued at 740 PM EDT Sat Apr 20 2024

Low level cold advection will continue this evening and
resultant steep low level lapse rates in this cold advection
should keep VFR stratocu in place. Low level thermal trough
settles across the region tonight with some drier air advecting
in from west to east later tonight into Sunday morning. This
drier low level air and passage of a positively tilted upper
trough should result in mostly sunny skies for late morning
Sunday through Sunday afternoon. With core of low level
anticyclone dropping across KS/MO, a modest gradient will remain
in place on Sunday that should support west-northwest gusts into
the 15 to 20 knot range from around midday Sunday through late
Sunday afternoon.

&&

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

&&

$$

DISCUSSION...Andersen
AVIATION...Marsili