Indianapolis, Indiana 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

617
FXUS63 KIND 220641
AFDIND

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

.KEY MESSAGES...

- Mostly Clear and cool weather tonight and Sunday.

- Warming trend begins on Sunday, continues through through
the upcoming week.

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

&&

.FORECAST UPDATE...
Issued at 958 PM EST Sat Dec 21 2024

Dry conditions are evolving as expected so far this evening across
central Indiana...en route to what should be the coldest overnight
for the remainder of the calendar year.  The inflection point amid
broad upper level flow...between a deep trough over eastern North
America and a more zonal ridge back through the northern Rockies...
will continue to pivot near Illinois.  An embedded H500 vort
currently crossing eastern Wisconsin will slide to the eastern
Midwest by daybreak....promoting at times SCT/BKN mid/high cloud
ahead of it over our local zones east of I-65.

Across the low-levels, the amplified ridge of polar high pressure
aligned from Ontario to the Lower Mississippi Valley will continue
to steadily drag its axis east across the region through dawn.  This
will result in light surface winds veering through easterly
directions.  Some concern over at least patchy fog developing given
more impressive radiational cooling so far under the southwestern
(clear) half of the CWA, where colder spots have already fallen into
the low 20s.  Nevertheless confidence too low so far to increase
patchy fog past the modest coverage now in the grids.  Lows tonight
expected around 20F north of I-70, with low 20s over southern zones.

&&

.SHORT TERM (This evening through Sunday)...
Issued at 309 PM EST Sat Dec 21 2024

Synopsis:

Surface analysis this afternoon shows strong high pressure in place
over Ontario, WI and IL. This was resulting in cold, northerly
surface flow across Central Indiana. GOES16 shows scattered diurnal
CU clouds across Central Indiana. Additionally, lake cloud was
blowing off of Lake Michigan across northern parts of Indiana.
Aloft, Ridging was found over the Rockies, while a trough was in
place over the east coast. This was resulting cooler NW flow aloft
with subsidence across the region. The Lake cloud was resulting in a
few flurries reaching Madison and Delaware counties as well as parts
of NE Indiana. Temperatures were in the low 30s.

Tonight and Sunday -

Quiet, benign weather is expected tonight and again on Sunday.

Through Sunday night, the strong high pressure system to the north
of Central Indiana will remain the major player in control of
Central Indiana`s weather. Models suggest this large, broad and cold
surface high will push to the eastern Great Lakes and Ohio by Sunday
morning, and then remain over NY State on Sunday. Indiana will
remain under it`s influence during this time, with backside
southerly flow developing on Sunday along with warm air advection.
Forecast soundings tonight and again on Sunday reveal a dry column,
with plentiful dry air and subsidence suggested. Aloft, northwest
flow is expected to remain in place as weak ridging builds toward
Indiana on Sunday. All of this amounts to support a dry forecast
with mostly clear skies.

Diurnal CU will be lost this evening as heating is lost, leading to
clear skies.  Given the dry dew points upstream in the teens, lows
overnight will fall to the teens and low 20s.

On Sunday with mostly sunny skies and stronger warm air advection
arriving aloft, high temperatures will start a warming trend
reaching the middle and upper 30s.

&&

.LONG TERM (Sunday night through Saturday)...
Issued at 309 PM EST Sat Dec 21 2024

The long term period will see a warming trend with multiple chances
for rain throughout the week and beyond thanks to a dynamic weather
pattern for the region. Highs will warm into the 40s for the first
part of the week with further warming for the latter part of the
week with highs in the 50s likely.

The larger upper level pattern will be a trough, progressing
eastward that will have several short wave troughs embedded within.
These shortwaves, as well as associated WAA and moisture advecting
from the Gulf, are what will help bring rain to the Ohio Valley and
Great Lakes regions next week.

To start the period off, flow will be relatively zonal with the
first system set to move across the upper Great Lakes with a
boundary stretched back to the southern Plains. Light rain will be
possible for central Indiana along this boundary with models showing
minimal accumulations from late in the day Monday through overnight.
Ahead of the rain, breezy winds will form with tighter pressure
gradients near the passing boundary.

The next system will quickly follow suit, this time with a few
tenths more for accumulations possible and the surface low itself
tracking closer to the Tennessee Valley. The more southern track
of that low will help to keep a bulk of the moisture south of
central Indiana but still won`t keep all the rain away from the
area for Christmas.

Finally, the end of the week will see the most potent of the systems
this week but still not seeing a concerning amount of precipitation
with it at the moment. Models lack agreement on how this last system
will play out but across solutions a decent surge of moisture from
the Gulf looks plausible with PWATs slightly above average for this
time of year.

&&

.AVIATION (06Z TAF Issuance)...
Issued at 140 AM EST Sun Dec 22 2024

Impacts:

- Isolated Fog for a few smaller airfields, otherwise VFR conds
prevail

Discussion:

Broad high pressure and a mostly dry column will lead to mainly VFR
flying conditions through the TAF period, although there is a small
chance for MVFR and or briefly worse fog at the smaller airports
overnight into early this morning per Hi-Res soundings.

Very light northeast to calm winds will become southerly up to 10
knots this afternoon as the high shifts to the east.

&&

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

$$

UPDATE...AGM
SHORT TERM...Puma
LONG TERM...KF
AVIATION...Beach