Forecast Discussions mentioning any of "ACARS" "MDCRS" "AIRCRAFT" "TAMDAR" "AMDAR" "WVSS" received at GSD on 06/07/23

Area Forecast Discussion

National Weather Service Indianapolis IN

 1010 PM EDT Tue Jun 6 2023

.Forecast Update...
Issued at 1010 PM EDT Tue Jun 6 2023

Only minor changes made to the going forecast overnight as a few
light showers move through the area. CAMs do indicate some potential
for a bit of an increase in coverage across the south/southwest late
tonight and will continue with middling chance pops in this area as
a result - capping at 40 percent given impact of the low level dry
air in place.

Temperatures appear to be in reasonable shape and will leave
minimums alone. Despite the cloud cover, some modest cold advection
and the aforementioned dry low levels should allow for the lows in
the mid 50s forecast in the northeast, while southwest areas remain
in the low to mid 60s.

&&

.Short Term...(This evening through Wednesday)
Issued at 234 PM EDT Tue Jun 6 2023

Rest of Today.

Latest ACARs soundings are showing the PBL has deepened to around
10,000ft but not quite at dry adiabatic levels.  This deep mixing
layer is allowing for the mixing out of dewpoints, but moisture
advection from the northwesterly winds is helping to counterbalance
the mixing with dewpoints generally in the upper 40s to around 50
across the area.  Current thoughts are that these should drop 3-5
degrees through 6 PM before gradually recovering during the
overnight hours.  Winds have begun to increase with the improving
lapse rates, but until 2-3 PM should remain infrequent.

Tonight.

A weak shortwave trough traveling along the more broad and strong
East Coast low pressure system will pass down Illinois into Indiana
during the overnight hours tonight with the potential for isolated
to scattered showers.  Much of the lift associated with the trough
is through the drier layers between 850mb and 500mb, but there may
be just enough forcing to overcome the dry layer and bring amounts
to around a tenth of an inch to the area.  Highest confidence in
precipitation will be across the southeastern counties where the
ambient surface moisture will be higher and some weak surface
convergence will be in place during the overnight hours.  The
increasing moisture and more abundant cloud cover during the
overnight hours will help keep conditions more mild with lows closer
to 60 expected.

Wednesday.

There may be a few lingering showers in the southern counties
through the morning hours, but dry air aloft will quickly work in
behind the exiting system and clear the skies by late morning.  The
surface flow will be oriented more northeasterly which will advect
cooler air into the area and keep temperatures limited to the upper
70s.

&&

.Long Term...(Wednesday night through Tuesday)
Issued at 234 PM EDT Tue Jun 6 2023

Changes are the horizon in the synoptic scale persistent central
CONUS blocking ridge and northeastern CONUS and eastern Canadian low
setup. Deterministic models and ensembles are in general agreement
that a wave will amplify over Manitoba and develop into a sharp
trough and later a closed low. The low is expected to pivot across
the lower Great Lakes late this weekend and early next week.
Although, there are run to run and model inconsistencies with this
feature. Nonetheless, this feature will force a cold front southeast
across central Indiana around Sunday. Model soundings are indicating
SSW flow will moisten the column along and ahead of the front and
upper low that will result in PWATs to around 1.5 inches. The
combination of synoptic forcing and deepening moisture may provide
the area with some much needed rain this weekend into early next
week, although it is still a bit early to gauge potential rainfall
amounts or even coverage. That said, Sunday looks to be the best
chance for rain with low PoPs reasonable by Saturday afternoon.
Instability does not look to be very impressive but the area is
pegged to be in the right rear quadrant of a seasonably moderately
strong 100kt upper Great Lakes speed max that could lead to enhanced
rainfall.

Less confidence in PoPs early next week as models and ensembles
differ in how long the upper low will hang around and what track it
will take. This will also lend lower confidence in temperatures but
overall look for cooler slightly below normal temperatures starting
Sunday due to the increased cloud cover and PoPs. Prior to the that,
stagnant pattern will likely keep temperatures above normal with
afternoon highs in the 80s.

&&

.Aviation...(00Z TAF Issuance)
Issued at 712 PM EDT Tue Jun 6 2023

Impacts:

* Light showers possible early in the period.

* MVFR ceilings possible at BMG Wednesday morning.

* Occasional wind gusts to around 15KT Wednesday afternoon.

Discussion:

A cold front and upper level disturbance moving through the region
will cause a wind shift to northerly and then northeasterly as the
period goes on, along with some light showers primarily early in the
period.

Ceilings will decrease a bit overnight but should remain VFR at all
but BMG, which may see a period of MVFR ceilings Wednesday morning.
VFR conditions should return by midday.

Winds will be 10KT or less throughout the period, gradually becoming
more northeasterly with time. Occasional gusts to around 15-16KT
appear possible during the day on Wednesday.

No significant obstructions to visibility are expected.

&&

.IND WATCHES/WARNINGS/ADVISORIES...None.

&&

$$

Update...Nield
Short Term...White
Long Term...MK
Aviation...Nield