Forecast Discussions mentioning any of "ACARS" "MDCRS" "AIRCRAFT" "TAMDAR" "AMDAR" "WVSS" received at GSD on 03/22/24

Area Forecast Discussion

National Weather Service Indianapolis IN

 937 PM EDT Thu Mar 21 2024

.KEY MESSAGES...

- Near freezing or below freezing temperatures northeast half tonight
- Light rain possible Friday afternoon and overnight
- Hard freeze expected Saturday night into Sunday morning
- Additional rain, possibly heavy early next week

&&

.FORECAST UPDATE...
Issued at 937 PM EDT Thu Mar 21 2024

Quiet...chilly conditions continue this evening with mainly clear
skies over central Indiana. Pockets of mid level clouds were
drifting across the region with coverage increasing over the upper
Midwest and western Great Lakes. 01Z temperatures ranged widely
from the lower 30s in some locations across the northern half of
the forecast area to the mid 40s in the lower Wabash Valley.

The forecast remains tranquil overnight as the Ohio Valley remains
between the storm system bringing wintry weather to the upper
Midwest and low pressure organizing over the southern Plains and
moving east. Mid level cloud coverage will increase across the
region during the predawn hours as moisture aloft advects into the
area from the northwest. Temperatures should have no problem falling
into the upper 20s and lower 30s over much of the forecast area with
ACARS soundings and RH progs highlighting very dry air through the
column.

Zone and grid updates out.

&&

.SHORT TERM (This evening through Friday)...
Issued at 250 PM EDT Thu Mar 21 2024

Rest of This Afternoon...

Based on latest trends seen on satellite, the initial area of mid
cloud across the northern forecast area will continue to gradually
thin out and/or exit. Meanwhile, some clouds across southern
Illinois will continue to move into the southern forecast area.
Thus, skies will average out partly cloudy.

A dry lower atmosphere will still bring low humidity values, but
lighter winds will continue to mitigate any fire weather threat.

Tonight...

Central Indiana will remain in between systems tonight. Some mid and
high clouds will move across the area at times, resulting in partly
cloudy skies. The lower atmosphere will remain quite dry with
surface winds still having an easterly component. Winds will remain
5 to 10 mph for most areas.

Cloud cover at times will help keep temperatures warmer than last
night`s. However, in periods of lighter winds and lower cloud cover,
temperatures will fall quickly with the dry air. Will go a little
below blended guidance due to this, with lows in the upper 20s to
middle 30s.

Friday...

A southern stream system will move across the southern USA during
Friday. An approaching cold front associated with the northern
stream will remain northwest of central Indiana until very late in
the period.

As the upper portion of the northern stream approaches on Friday
afternoon, it may be able to tap into the fringes of the southern
system`s moisture and perhaps produce some showers. However, forcing
will be weak, and the lower atmosphere will take a long time to
moisten up as winds don`t become southerly until afternoon.

Given the weaker forcing and limited moisture, will only go with
some chance PoPs southeast during the afternoon. Will also put some
low chance PoPs late in the day northwest as the cold front
approaches.

The southerly winds will bring warmer air back to the area. If winds
become southerly sooner and cloud cover is lower, temperatures could
reach the mid and upper 60s. However, for now, will stick with lower
to middle 60s.

&&

.LONG TERM (Friday night through Thursday)...
Issued at 250 PM EDT Thu Mar 21 2024

Friday night through Sunday night...

A cold front moving through early in the period will potentially
bring light precipitation to the area. Confidence in precipitation
chances have decreased for multiple reasons. A large broad surface
low associated with a southern stream trough across the south should
limit deeper moisture return ahead of the front. This along with
relatively weak overall forcing limits confidence in shower
coverage. POPs have been lowered over the area as a result. The cold
front is likely to move through late Friday night with cooler air
filtering in.

Surface high pressure building in will provide quiet weather
conditions over the weekend. Cold air advection should provide a
brief cooldown before temperatures begin to rebound. Expect below
normal temperatures for Saturday ranging from 43F-52F for highs and
lows in the mid-upper 20s. The cold overnight temperatures will
likely cause additional impacts to any vegetation that has greened
or bloomed. Look for temperatures to begin moderating towards the
end of the weekend as surface flow becomes southeasterly. Highs will
be near seasonal by Sunday.

Monday onward...

The weather pattern is likely to be more active next week with an
occluded surface low and deep broad trough moving into the region.
Some uncertainty remains in exact details, but anomalous moisture
return and increasing dynamics should support widespread
precipitation which could be heavy at times. Ensemble guidance shows
the bulk of precipitation falling from late Monday through Tuesday
evening. There is a low chance that light precipitation could linger
into Wednesday depending on how long it takes for the system to
exit. Expect increasing southerly flow to quickly warm temperatures
well into the 60s on Monday. A tightening pressure gradient is also
going to result in windy conditions early next week.

The highest uncertainty in the current forecast is expected rainfall
amounts. Initially a cold front associated with the occluded surface
low moving over the Upper Midwest will support increasing rain
chances. The forecast then becomes more complicated as guidance
suggest another surface low could develop across the south. Some
models show the low tracking towards the region along the
baroclinic zone associated with the aforementioned cold front
while others keep the system further south. If the system were to
remain further south then this would likely limit deeper gulf
moisture return and overall rainfall amounts. Forecast confidence
will increase in the coming days as model guidance becomes better
aligned.

&&

.AVIATION (00Z TAF Issuance)...
Issued at 638 PM EDT Thu Mar 21 2024

Impacts:

- None

Discussion:

Dry easterly flow continues early this evening as a high pressure
ridge moves away to the east. Expect periodic mid level clouds over
the region tonight into Friday morning as slightly deeper moisture
aloft advects into the area. Cloud coverage will gradually increase
Friday afternoon as a cold front approaches from the northwest and
moisture associated with low pressure tracking across the Gulf Coast
states spreads north into the Ohio Valley. Will see a few light
showers develop late afternoon but ceilings will remain VFR. Winds
will veer to southeast during the day then become variable in
direction before shifting to northerly Friday night as the front
passes by.

&&

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

&&

$$

UPDATE...Ryan
SHORT TERM...50
LONG TERM...Melo
AVIATION...Ryan