Area Forecast Discussion
Issued by NWS Indianapolis, IN

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000
FXUS63 KIND 151851
AFDIND

Area Forecast Discussion
National Weather Service Indianapolis IN
251 PM EDT Fri Mar 15 2024

.KEY MESSAGES...

- Clearing tonight, warmer on Saturday.

- Breezy during daytime Saturday through Monday

- Much colder early week with freezing temperatures Sunday night

- Hard freeze Monday night

&&

.SHORT TERM (This evening through Saturday)...
Issued at 250 PM EDT Fri Mar 15 2024

Synopsis:

Surface analysis early this afternoon shows strong high pressure in
place over Nebraska. Low pressure was centered over southern New
England with a cold front that stretches southwest across the middle
Atlantic States to Central TN. Heavier precipitation with this
system was found mainly south of this front and KIND radar has gone
quiet. GOES16 shows clearing skies across the northern parts of
Central Indiana with high CI blow off still in place across the
southern half of the state due to convection upstream over Arkansas
and Mississippi. Water vapor imagery shows a merging of the northern
upper flow and southern upper flow across the Tennessee and Ohio
river valleys. Central Indiana was mainly impacted by the northern
flow, providing cooler and NW flow across our state.

Tonight...

Clearing and quiet weather will be expected.

Models suggest the surface high pressure system over NB will extend
a ridge axis toward and across Central Indiana tonight. This will
lead toward cooler northwest flow initially this evening, however as
the axis shifts to the southern parts of Indiana overnight winds are
expected to become southwesterly, leading to the onset of warm air
advection. Aloft, northwest flow remains predominate, with a wave
within that flow over Canada, poised to push into Indiana on
Saturday. Little in the way of forcing dynamics or moisture remain
present within this flow overnight. Thus we will trend overall
toward skies becoming mostly clear and cooler lows in the
middle 30s.

Saturday...

The previously discussed wave over Canada is expected to
sag southward across Indiana and the Great lakes on Saturday,
passing through the course of the day. Meanwhile at the surface the
ridging is expected to sag farther southward while deeper low
pressure develops just north of the Great Lakes. This will allow for
the set up of a moderate pressure gradient across Central Indiana.
As the upper forcing passes, little in the way of moisture for this
system will be available. Forecast soundings remain very dry and
time heights just hint at some passing mid level clouds within the
flow aloft. Thus will continue with a dry forecast and partly cloudy
skies on Saturday. Given the development of gusty southwest flow and
warm air advection, highs in the lower 60s will be expected.

&&

.LONG TERM (Saturday night through Friday)...
Issued at 250 PM EDT Fri Mar 15 2024

The long range looks quiet, for the most part, as northwesterly flow
dominates the flow pattern aloft. Across the West Coast, ensemble
guidance shows blocking taking shape, which in turn amplifies the
large-scale wave pattern. Ridge-building extending northward out of
the Pacific Northwest is likely to dislodge Arctic air southward,
although bitterly cold temperatures will be modified by increasingly
strong solar insolation. A potent trough looks to dive southward on
Sunday together with a strong cold front. Despite very warm air in
front of the approaching boundary, very little moisture
exists...much of it having been pushed southward by yesterday`s
front. As such, little in the way of precipitation is anticipated
with the frontal boundary as it passes through Saturday night. Below-
freezing temperatures are highly likely each morning Sunday through
Wednesday. Sensitive vegetation may need to be protected.

Early next week, ensembles show western blocking breaking
down...allowing the upper flow pattern to become more zonal.
Guidance also hints at the polar and subtropical streams remaining
separate, which should preclude significant northward moisture flux.
Moderating temperatures with little in the way of precip is expected
for the coming week. There are some signs in guidance that the two
streams become a bit more phased, which allows a deeper trough to
emerge from the western States late in the week. Blended guidance
gives roughly 50 percent PoPs by Friday, which given the time frame
we are looking at is fairly high.

&&

.AVIATION (18Z TAF Issuance)...
Issued at 100 PM EDT Fri Mar 15 2024

Impacts:

- IFR ceilings early improving to VFR.

Discussion:

Satellite imagery across Central Indiana continues to indicate low
clouds over the southern half of the state with clearing found
across the northern 1/3 of the state. High clouds from convection
over Arkansas was streaming across southern Indiana within the flow
aloft.

The high pressure system to the west is expected to build a ridge
axis with associated subsidence across Central Indiana tonight and
on early Saturday. Forecast soundings and time heights trend toward
a dry column tonight and on Saturday as this occurs, thus a return
to VFR is expected tonight and this will persist on Saturday.

A moderate pressure gradient is expected to develop on Saturday as a
deep area of low pressure moves across Ontario. This will result in
some gusty winds of 20-25 knts on Saturday afternoon.


&&

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

&&

$$

SHORT TERM...Puma
LONG TERM...Eckhoff
AVIATION...Puma


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