305
FXUS63 KIND 270137
AFDIND

Area Forecast Discussion
National Weather Service Indianapolis IN
937 PM EDT Fri Jul 26 2024

.KEY MESSAGES...

- Slightly warmer Saturday with increased cirrus clouds

- Increasing rain chances Sunday

- Increasing threat for multiple storm clusters to impact the region
  next week

&&

.FORECAST UPDATE...
Issued at 935 PM EDT Fri Jul 26 2024

Fair weather will be the rule overnight as broad surface high
pressure centered over far southeastern Ontario continues to prevail
over most of the Midwest.  A dry column will promote rain-free
conditions while allowing only cirrus clouds...which will be FEW in
number north of a Terre Haute to Seymour line, closer to the slowly-
departing ridge.  Light winds spilling out of the high will
continue to prevail from generally easterly directions, although
flow will likely go variable by pre-dawn hours for most sheltered
and low-lying areas.

Decreasing dewpoints are expected to outrun any potential for
patchy fog formation. Below normal minimum readings tonight will
range from the mid-50s in Fishers and to points north/east...to
the low 60s inside Interstate 465 and across most areas to the
south/west.

Grids and update out.

&&

.SHORT TERM (This evening through Saturday)...
Issued at 227 PM EDT Fri Jul 26 2024

Various satellite products show western wildfire smoke at minimal
magnitude and most concentrated west of us over Illinois, near the
base of an upper level trough. So, minimal obscuration is currently
being observed. Trajectories and HRRR smoke model suggest minimal if
any haziness will be observed through the short term period, as most
of the smoke will be relegated to the polar jet at higher latitudes
in Canada.

Diurnal cumulus will diminish this evening with loss of surface
diabatic heating. Meanwhile, amplification of ridge of subtropical
jet will result in increased cirrus coverage through tomorrow. With
increased ridging will come slightly warmer temperatures, to about
late July climatology (mid-upper 80s).

Some diurnal cumulus is again expected tomorrow. Richer moisture per
IVT plots will hold to our southwest through the day tomorrow,
though high-level moisture will increase downstream of Plains upper
low, further enhancing cirrus coverage.

&&

.LONG TERM (Saturday night through Friday)...
Issued at 227 PM EDT Fri Jul 26 2024

Saturday Night Through Tuesday.

Quiet weather is expected for the start of the long term period, but
conditions are expected to become active through much of next week
as ridging across the Ohio Valley breaks down and the pattern favors
northwesterly flow as the ridge across the Rockies builds. Ahead of
the northwesterly flow, rain chances begin to increase going into
Sunday as a weak trough interacts with the moist airmass to bring
scattered showers and a few thunderstorms Sunday afternoon. Isolated
showers are expected to persist through early Monday with a fairly
stagnant airmass in place but by Monday night the aforementioned
northwesterly flow aloft will begin to dominate the weather pattern.

The first threat for ridge-riding thunderstorms will be Monday night
into early Tuesday with fairly good model agreement in potential
impacts to Indiana but with only marginal shear, not expecting a
high severe threat with a strong cold pool looking unlikely. This
may set the table though for potential flooding later into the week
if successive storm complexes further impact the same area.

Wednesday Through Friday.

The next most likely potential for a storm complex will be
Wednesday, but there remains quite a bit more model uncertainty as
to whether this system would impact Indiana.  This system is more
likely to occur during the late afternoon through early evening
hours which should allow for a more organized thunderstorm complex
with much better shear and instability compared to the storms
earlier in the week.  This system if it ends up impacting Indiana
has the potential for both damaging winds and isolated flooding.

There could be additional rounds of storms Thursday into Friday but
this will all be dependent on how the mesoscale environment is
impacted by the storms earlier in the week with low confidence on
even the synoptic environment by Friday as models rapidly diverge.
What does look likely is between Friday and Sunday, a more organized
upper level low should drop southeast from Canada with impacts to
the general Great Lakes Region.

Confidence in temperatures towards the middle to end of next week
begins to fall off with the general pattern favoring temperatures
near 90, but overnight convection may leave cloud debris which could
cause for some days to end up closer to 80.

&&

.AVIATION (00Z TAF Issuance)...
Issued at 713 PM EDT Fri Jul 26 2024

Impacts: None

Discussion:

VFR conditions to continue through Saturday evening as central
Indiana remains under the southwestern portions of broad surface
high pressure aligned from the southern Great Lakes to the Jersey
shore. SCT/BKN cirrus should stay mainly south/west of terminals
through midday Saturday...before returning northeastward during
the afternoon.

Generally east-northeast winds will be light if not variable
tonight...before veering to more east-southeasterly flow Saturday
morning albeit continued light.

&&

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

$$

UPDATE...AGM
SHORT TERM...BRB
LONG TERM...White
AVIATION...AGM