Indianapolis, Indiana 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

493
FXUS63 KIND 221156
AFDIND

Area Forecast Discussion
National Weather Service Indianapolis IN
656 AM EST Sun Dec 22 2024

.KEY MESSAGES...

- Warming trend begins today, continues through the upcoming week

- Numerous chances for rain for next week, including Christmas Day,
but precipitation amounts look minimal

- Temps possibly flirting with upper 50s to around 60 by Fri and Sat

&&

.SHORT TERM (Today and tonight)...
Issued at 223 AM EST Sun Dec 22 2024

Relatively tranquil weather pattern remains over the Ohio Valley
today, as high pressure remains the key feature albeit centered just
east of the region. This will result in stable atmospheric
conditions across Central Indiana today. Weak pressure gradient
oriented from the southeast turning southerly should keep winds
under 10kts for much of the day. Minimal moisture throughout the
boundary layer will also translate into minimal clouds today but
there is a narrow ribbon of moisture around 15KFT AGL that could
result in a few cirrus based clouds traversing the area this
afternoon.

With parcels seeing minimal moisture presence at the surface, expect
a slow and steady warming trend this morning across Central Indiana
with temperatures approaching seasonal conditions or possibly a
touch above seasonal south of Indy Metro. The longwave pattern
overhead is still depicting a weak ridge axis at 500mb displaced
across the Eastern CONUS that is aiding in the weak height gradients
over the Ohio Valley and also resulting in the weak upper level
flow.

Tonight...Anti-cyclonic ridge will continue to drift east, which
will allow the boundary layer isallobaric gradient to return.
Orientation of the gradient will be southwest to northeast along the
western periphery of Central Indiana, fortunately this will occur
during the nocturnal period and the lack of a well mixed near
surface environment should keep things decoupled for the most part
and winds will likely just be in the 5-10kt range. There is some
indication that ascending parcels could strengthen in the mid-lvls
after midnight enough to further thicken the cloud shield that will
be cirrus based. But confidence in this scenario remains minimal at
the moment. The longwave pattern is still progressive in the zonal
orientation, but there will be a developing mid-lvl trough axis
across the Northern Plains that will begin to slide south, this will
become the next feature to monitor for Monday.

&&

.LONG TERM (Monday through Saturday)...
Issued at 223 AM EST Sun Dec 22 2024

Monday...Upper level flow will feature a 500mb trough steadily
sliding east/southeast into Great Lakes region. This will cause a
slight modification to geopotential heights across Central Indiana,
with an associated boundary layer pressure gradient oriented from
the southwest to northeast along the lee-side of a developing
surface vorticity feature in Wisconsin. This will cause parcels to
ascend through a moistening column across Indiana midday. With
presence of some minimal forcing through the mid-lvls that will be
seeing an increase in moisture, it is favorable that as precip
develops it will likely be small hydrometeors at onset Mon
afternoon. With a thickening cloud footprint, this should prevent
temps from warming too much from the low/mid 40s despite the modest
thermal ridge that is advecting warmer air into Central Indiana.

A boundary does appear to become quasi-zonal oriented over Indiana
late Mon eve, which could prolong the drizzle or light rain. The one
concern for Mon ngt could end up being a decoupled boundary layer
that is saturated and might lead to a period of some patchy fog with
more drizzle.

Christmas Eve - Tuesday...500mb weak ridging will sneak into the
Ohio Valley which will be coupled with a weak area of warm air
advection beneath at 850-700 mb layer as a thermal gradient across
Central Indiana will begin to lift northward. Overall Tue should
still produce a stratus layer across the region in advance of the
next mid-lvl trough axis that will be developing across the southern
Plains. It is possible diffluent air and some weak height rises in
the near surface environment will translate into a mostly dry Tue,
but expect an increase potential for precip in the western portions
of the forecast area by late Tue.

Christmas - Wednesday...Mid-lvl trough axis continues to demonstrate
some modest strengthening, which may result in a slight negative
tilt to the surface shortwave that will be lifting into Southern MO.
Strong V-wind component will be in place ushering in additional
moisture ahead of the evolving shortwave. This will couple with
ascending parcels and expand the precip footprint across much of
Central Indiana by mid-morning Christmas Day. Expect at onset
droplets will likely be smaller, but with added forcing and a
strengthening mid-lvl shortwave as the day progresses the precip
shield will likely become more steady rain in portions of Central
Indiana. Continued unseasonably warm surface will keep temps in the
40s possibly near 50 in the far southern portions of Central
Indiana.

Thursday...Amplified shortwave trough quickly pivots east of the
region, with a weak area of divergence aloft in the wake from a
potent jet streak. This should allow for a period of stronger upward
vertical motion but should be short-lived as the progressive pattern
continues and modest height rises return to the mid-lvls across the
Great Lakes and Ohio Valley. Stronger mid-lvl vort max progged for
the lee-side of the rockies, with a surface feature taking shape.
Strong meridional flow returns but with a delayed moisture return,
this time with a stronger thermal ribbon advecting north into
Central Indiana. Expect a nice surge ahead of the next system, with
temps likely nearing the low/mid 50s. If there is enough breaks in
clouds in the morning hours, might even see temps push higher.

Friday through Saturday...Similar pattern to close out the active
weak, with the continued southerly flow of moist and warm/mild air.
The difference for Fri and Sat could be that temps will be flirting
with the upper 50s to lower 60s.

Weeks 2 Through 4 Period:

While the period will begin mild...the long wave pattern is expected
to shift toward the new year as a building western ridge allows a
deep trough to develop across the central and eastern CONUS by early
January with several potential short waves crossing the region
through mid month.

The period from Christmas to the beginning of the new year looks
very mild but also likely to be wet with an above normal
precipitation signal lined up through the Ohio valley. With warm
temperatures this precipitation should be mostly in the form of rain
with even a possibility of thunder at times.

As pattern begins to shift near New Years, timing of colder air
infiltration with pcpn signals will need to be watched for
possibility of snow as this transition develops. Once cold air
becomes established...there is uncertainty with regards to pcpn
signals. Below normal precipitation is favored in the GFS and EC
weekly anomalies, and favored by CPC, but CFS looks rather active
with several short waves and potential storm systems crossing the
central CONUS. This could bring rain or snow depending on storm
tracks and timing which cannot be resolved by any means at these
projection times. Overall temperatures during this period should be
near or below normal.

&&

.AVIATION (12Z TAF Issuance)...
Issued at 656 AM EST Sun Dec 22 2024

Impacts:

- No Impacts through current TAF period

Discussion:

High pressure continues to provide VFR conds for all airfields in
Central IN early this morning, and projected to persist through the
current TAF period. High pressure will slowly push east of the
region this afternoon into the evening, and allow winds to turn
southeasterly and increase to around 7kts. Then early Mon clouds
will increase along with winds increasing from the south. Precip
chances will increase by Mon afternoon with a few MVFR CIGs.

&&

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

$$

SHORT TERM...Beach
LONG TERM...Beach
AVIATION...Beach