104
FXUS63 KIND 241621
AFDIND

Area Forecast Discussion
National Weather Service Indianapolis IN
1221 PM EDT Sat May 24 2025

.KEY MESSAGES...

- Below normal temperatures continue, mainly highs in the 60s and
  lows 45-55 degrees into early next week

- Scattered showers over far southwest central Indiana Sunday with
  better chances over the entire area Monday night through Wednesday

- Temperatures recovering to near normal levels by the second half
  of next week

&&

.FORECAST UPDATE...
Issued at 919 AM EDT Sat May 24 2025

Skies were mainly clear this morning across the northeast half of
central Indiana with mid and high cloud debris from convection
across the Ozarks back into eastern Oklahoma. Cool easterly flow was
in place with 13Z temperatures in the 50s.

The current forecast is in solid shape for the remainder of the day
as high pressure centered over the Great Lakes keeps rain and
convection well to our southwest throughout the day outside of a
stray sprinkle this afternoon across far southern counties. The
northern flank of the mid and high level clouds associated with that
convection will persist across the southwest half of the forecast
area for much of the day and will likely produce a mostly cloudy sky
for the afternoon. Further to the northeast...expect scattered
diurnal cu to form by late morning courtesy of surface heating and
while sun will be more plentiful than further southwest...expect
cloud coverage to increase here as well into the afternoon.

Nudged highs back slightly with the increasing clouds...but expect a
range of mid 60s northeast into the lower 70s southwest this
afternoon. Zone and grid updates out.

&&

.SHORT TERM (Today and tonight)...
Issued at 310 AM EDT Sat May 24 2025

The short term features fairly benign conditions for all of Central
Indiana as high pressure remains the dominant weather influence at
the surface. A northwest flow regime aloft will advect in higher
clouds this morning and through the weekend with the best moisture
advection and forcing for ascent remaining well south and west of
Indiana. A very cool airmass is still in place over the Great Lakes
as the source region from the high overhead is from Central Canada.
E/NE winds today will keep this cooler airmass at the surface, while
higher clouds limit substantial surface heating. ACARs soundings
over the past 12 hours show a fairly high subsidence inversion
aloft, around 750mb, allowing for deep mixing and steep lower and
mid level lapse rates during peak heating of the day. Despite a cool
airmass overhead, this deeper mixing and periods of sunshine today
should allow for surface temperatures to make it into the upper 60s
to lower 70s. Winds through the mixed layer are fairly light, so
even with deeper mixing winds should remain under 10 mph.

For tonight, not expecting temperatures nearly as cold as the past
few nights where some rural, low lying locations dropped into the
upper 30s with patchy frost. Higher clouds and light NE winds should
prevent temperatures from plummeting too much overnight. Forecast
lows range from the mid 40s in North Central Indiana to the low to
mid 50s in SW and South Central Indiana.

&&

.LONG TERM (Sunday through Friday)...
Issued at 310 AM EDT Sat May 24 2025

The long term period starts off on a dry and mild note across
Central Indiana; however wet weather returns next week for portions
of the state.

.Sunday...

High pressure keeps its influence on surface conditions for Central
Indiana on Sunday, while an area of low pressure and frontal
boundary approach from the southwest. Aloft, forecast soundings
indicate moisture advection increasing in the mid and upper levels
as subtle waves pass through within the jet stream resulting in
mostly cloudy skies Sunday. Dry antecedent conditions and lack of
low level moisture advection should keep the boundary layer dry
enough to inhibit precipitation development across most of Central
Indiana. The best forcing for ascent and moisture for precipitation
should remain further south in the lower Ohio Valley and Ozarks
where the warm frontal feature sets up. Model trends over the past
several days support this set up keeping rainfall away from the
region until at least late Monday night.

Some guidance tries to portray isolated showers over Central Indiana
Sunday, however in reality, this will likely present itself as
virga. So while it may look like it could rain Sunday, dry lower
levels will likely result in rainfall evaporating before reaching
the surface. Would not rule out a drop or two making it to the
ground, especially south of I-70, but overall expect a dry day.

Clouds and NE winds keep temperatures below average for this time of
year with highs only in the mid 60s.

.Next week...

The overall weather pattern begins to shift next week as the upper
jet becomes more west-southwesterly aloft and the storm track lifts
northward into Indiana. Closer to the surface, high pressure begins
to lose its influence over the state as a developing area of low
pressure in the Plains and associated frontal boundaries lift
northward into Indiana. Low pressure is expected to ride along the
warm front extending over the Ohio Valley and provide perhaps the
best opportunity for more widespread rain and embedded thunderstorms
Monday night through Tuesday. The focus for greatest convective
coverage will again be over southern counties in closest proximity
to the warm front and track of the surface low. By Wednesday, an
upper low will be in place over the Upper Great Lakes while Indiana
is in in the wake of the passing surface low to the east. While it
is difficult to forecast subtle waves within the upper jet this far
out, this pattern would support continued mostly cloudy conditions
with showers as weak waves rotate around the upper low to the north.
Keeping the forecast more pessimistic mid week based on the overall
weather pattern.

Confidence decreases mid to late next week and into the following
weekend as some longer range models have been consistent in showing
another cut off low pattern developing. Guidance usually struggles
with patterns featuring weakly forced systems, so confidence remains
low in the finer details this far out. For now, keeping a close eye
on the potentially cool and wet pattern going into early June as any
warm up back to normal may be fairly brief.

Should the forecast pan out with highs remaining below 70 through at
least Tuesday here at Indy, this would mark a consecutive string of
8 straight days of sub-70 degree weather extending back to this past
Tuesday 5/20. The last time Indianapolis experienced this for such a
long period of time this late in the Spring was from 5/25 to 6/2 in
1889. The search for a return to more persistent warmth likely is
still 7-8 days out and possibly beyond with 80s likely to return by
early in the week of June 2.

&&

.AVIATION (18Z TAF Issuance)...
Issued at 1221 PM EDT Sat May 24 2025

Impacts:

- None

Discussion:

VFR conditions will continue through the forecast period. Dry
weather continues through tonight as the region resides under the
influence of high pressure over the Great Lakes. Mid and high level
clouds will however continue to drift through the area with a warm
front to the southwest of the region from the southern Plains east
into the Tennessee and lower Ohio Valleys. E/SE winds near 5-10kts
will become light overnight.

The boundary will lift closer to the region Sunday but the airmass
will largely remain dry below the 800 to 750mb layer. An increase in
isentropic lift may enable sprinkles to impact the terminals at
times on Sunday. Northeast winds will be under 10kts.

&&

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

&&

$$

UPDATE...Ryan
SHORT TERM...CM
LONG TERM...CM
AVIATION...Ryan