Greenfield, Indiana 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

942
FXUS63 KIND 300222
AFDIND

Area Forecast Discussion
National Weather Service Indianapolis IN
922 PM EST Wed Jan 29 2025

.KEY MESSAGES...

- Above average highs mostly in the 40s and 50s into early next week

- Rain expected Thursday afternoon into Friday, with rainfall amounts
  from around a half inch to near an inch (highest south).

&&

.FORECAST UPDATE...
Issued at 922 PM EST Wed Jan 29 2025

Clear skies continue across the region this evening as high pressure
slides by to the south. Winds had lightened considerably from
earlier and temperatures had fallen in response since sunset with
02Z readings in the 30s.

The forecast for tonight is in great shape. The high will drift off
to the east overnight but remain the primary influencing feature with
model soundings and RH progs highlighting an abundance of dry air and
subsidence through the column. The expanding cloud shield lifting
out of the southern Plains and lower Mississippi Valley will
gradually expand towards the Ohio Valley with the leading edge of
high level clouds likely expanding into southern portions of central
Indiana near or just after daybreak Thursday.

With winds becoming light and variable overnight...expect a good
radiational cooling setup which will enable a cooler night than
Tuesday night. Lows will fall predominantly in the the upper 20s.
Zone and grid updates out.

&&

.SHORT TERM (This evening through Thursday)...
Issued at 246 PM EST Wed Jan 29 2025

Quiet weather will continue overnight into early Thursday, as an
elongated area of surface high pressure from the southeastern US
into the Missouri Valley steadily slides eastward toward the east
coast overnight.

A closed upper level low ejecting east/northeastward out of the Four
Corners region will push toward central Indiana during the day on
Thursday, with some weak isentropic lift pushing into the area by
midday. That said, a fairly dry antecedent low level airmass, along
with integrated water vapor transport (IVT) progs that suggest the
best moisture transport will be off to our south for much of the day
and perhaps beyond imply that rain onset in central Indiana, which
will come from the southwest, will likely be no earlier than about
late morning to midday, with much of the area remaining dry until
the afternoon hours.

Additionally, ensemble probability matched mean values suggest
relatively light amounts for most of the area tomorrow, with WPC
amounts of up to a quarter to half inch in the far south/southwest
looking quite reasonable despite fairly good synoptic forcing for
ascent, as more robust convection to the south may account for the
aforementioned weaker IVT into the area.

Low temperatures tonight will be slightly above normal, though did
go a bit below blend numbers with fairly good radiational cooling
conditions in place. The mid to upper 20s appear to be a good bet
for lows tonight.

Fairly strong low level warm advection tomorrow will push highs back
into the mid 40s to low 50s, though increasing cloud cover and
evaporative cooling as rain begins later in the day will limit this
a bit. Did go above blend numbers a bit owing to later onset of
rainfall across most of the area.

&&

.LONG TERM (Thursday night through Wednesday)...
Issued at 246 PM EST Wed Jan 29 2025

Thursday Night and Friday...

As the upper low approaches the area Thursday night, southwesterly
flow will continue to pump in moisture to the area. Forcing from the
system will work with this moisture to bring rain to central
Indiana. Will go high PoPs all areas Thursday night.

Models have been trending farther south with the heaviest rain as
the 850mb jet is pointed more into Kentucky. Frontogenetic forcing
will now be shifted southeast as well, and convection to the south
may rob moisture up this way. Thus, any heavy rain threat looks to
be south of central Indiana, and QPF will be lower than previously
thought.

On Friday morning, the dry slot of the system will work into the
area and lower the coverage of rainfall, especially south. Friday
afternoon, the TROWAL associated with the system will move across
northern Indiana and could bring more rain to northern portions of
central Indiana. Will keep some low end likely PoPs in the north
Friday afternoon.

Rainfall amounts now look to be around a half inch across the
northern half of central Indiana, with a tight gradient to around 1
inch in the far south.

Temperatures will be able to warm into the upper 40s to middle 50s
on Friday.

Saturday into Tuesday...

Near zonal flow aloft will keep cold air bottled up to the north and
forcing with any systems to the north as well. Will go with a dry
forecast with above normal temperatures through this period.  The
warmest days will be Sunday and Monday when highs will be in the 50s
for a good part of the area.

Wednesday and beyond...

Uncertainty ramps up to higher than usual for this far out as models
are struggling on how much cold air moves into the area. If an upper
trough in the northwest USA is deeper, upstream ridging will keep
colder air at bay for central Indiana. If the system is weaker,
ridging would be weaker and allow colder air in.

Blended guidance differences between the 25th and 75th percentiles
for Indy range from a high of 37 to a high of 57 respectively. For
now will just stick near the 50th percentile highs in the lower to
middle 40s most areas.

Some rain is possible as the colder air tries to work in, so will go
with low PoPs for now.

&&

.AVIATION (00Z TAF Issuance)...
Issued at 553 PM EST Wed Jan 29 2025

Impacts:

- Winds relaxing this evening and becoming light and variable
- Deteriorating conditions by mid to late afternoon Thursday as rain
  overspreads the terminals

Discussion:

High pressure remains across the region this evening and will keep
skies mainly clear through daybreak Thursday. Westerly winds are in
the process of decreasing and will become light and variable
overnight as the center of the high passes by to the south.

Mid and high level clouds will encompass the terminals by midday
Thursday as progressively deeper moisture advects into the Ohio
Valley. Low pressure will track into Arkansas and Missouri by
Thursday evening with a warm front extending east near the Ohio
River. As moisture and lift increase over the region...rain will
become widespread over central Indiana by late afternoon. Expect
ceilings to drop rapidly with the onset of rain...with IFR
conditions developing near the end of the forecast period. Winds
throughout the day Thursday will be from the S/SE at 5-10kts.

&&

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

&&

$$

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