489
FXUS63 KIND 112237 AAA
AFDIND

Area Forecast Discussion...UPDATED
National Weather Service Indianapolis IN
637 PM EDT Tue Jun 11 2024

.KEY MESSAGES...

- Mostly Clear and Mild Tonight and Wednesday

- Warming trend beginning Wednesday, highs near 90 for Thursday

- Cold front Thursday night with chance for rain/storms

- Much warmer weather Monday into Tuesday

&&

.FORECAST UPDATE...
Issued at 637 PM EDT Tue Jun 11 2024

Forecast chances this evening will be minimal. We`ve lowered
temperatures slightly given an MSLP pattern supporting good
radiative conditions. Dry low-level air mass should preclude fog.
Light/variable winds may strengthen slightly by morning and shift
to southerly.

&&

.SHORT TERM (This evening through Wednesday)...
Issued at 224 PM EDT Tue Jun 11 2024

Synopsis:

Surface analysis early this afternoon shows a large area of high
pressure in place stretching from southern Ohio, across southern MI
and IN to SE MO. The high was controlling the weather across Indiana
and the region. Cool and light north to northwest were in place
across Central Indiana. Dew points across the area remained in the
comfortable middle 40s. Aloft a strong ridge axis of high pressure
was found stretching from MO to Lake Michigan and then northeast
toward NE Ontario and NW Quebec. This was resulting in strong lee
side subsidence across Michigan and Indiana. However a plume of
moisture was found on the windward side of the ridge over WI/IA and
much of IL. GOES16 shows clear skies across the state, but some mid
and high clouds were found across WI and IA, ahead of an approaching
surface trough.

Tonight...

Models suggest that the previously mentioned upper ridge axis will
slowly diminish tonight and drift east. This will leave northwest
Pacific flow aloft to the upper Midwest, spilling southeast to the
Ohio Valley. A weak upper wave within flow is expected to pass
within this flow aloft. The lower levels will remain quite dry
though. After two days of strong subsidence and dew points in the
40s, sufficient lower level moisture for precipitation will not come
to pass. Lower levels also remain unfavorable for precipitation as
the surface high pressure system is suggested to become elongated,
stretching from NY/PA to across the Ohio Valley. This will
effectively block any gulf moisture. Forecast soundings show a dry
column through the night. Thus only some high passing clouds will be
expected due to the passing wave aloft. The progression of these
high clouds will be able  to followed as seen on GOES16, as they
reside over IA and WI. With weak warm air advection in place tonight
along with some expected high clouds, lows will not be as chilly
tonight. Look for lows in the lower to middle 50s.

Wednesday...

The flow aloft on Wednesday is expected to be a continued Pacific
northwest flow. Little in the way of forcing dynamics appear to pass
as the overnight wave departs to the east. Within the lower levels
the previously mentioned high pressure system stretching across the
Ohio Valley will remain in place, providing weak southerly flow to
Central Indiana along with the beginning of warm air advection.
850MB surface shows moderate warm air advection through the day as
temperatures rise to near 16C by 00Z Thursday. Forecast soundings
continue to show a dry column with unreachable convective
temperatures. Thus another sunny day will be expected with warmer
temperatures. Look for highs in the middle 80s.

&&

.LONG TERM (Wednesday night through Tuesday)...
Issued at 224 PM EDT Tue Jun 11 2024

Wednesday Night Through Friday.

Conditions are expected to remain quiet through early Wednesday
evening with gradually warming temperatures as the stronger
northwesterly flow comes to an end and the surface air becomes more
stagnant ahead of a return to southerly flow later into the week.
There is a conditional risk for thunderstorms late Wednesday evening
with an approaching MCS, but there is fairly high confidence that
this system won`t be able to reach even the far northwestern
counties. The first shot of precipitation is expected late Thursday
evening into the early overnight hours as a cold front approaches
the area. There is at least some signal within the models for a
storm complex late Thursday night ahead of the front, but this
remains very uncertain more than 72 hours out. There should be just
enough lift with the front for at least isolated shower coverage,
but confidence is low.

Models are coming closer in line to the idea that temperatures will
be cooler on Friday with the NBM bringing highs closer to 80 than
the mid to upper 80s that had been suggested in days prior.  Even
that may be a bit warm with the northerly flow expected.

Saturday Through Monday.

The aforementioned ridge of high pressure will gradually shift
eastward going into the weekend in the aftermath of the frontal
passage. Confidence on the temperatures is low and will be dependent
on the final strength of the cold front with models gradually
trending towards a cooler for Saturday before the ridge moves
overhead late Saturday into Sunday. Surface high pressure off the
coast of Georgia and also across the Northern Plains will help to
funnel Gulf air into the Ohio Valley Sunday into Monday which will
bring some of the most humid air of the year by Monday with
dewpoints in the upper 60s to low 70s combining with highs in the
low to mid 90s to create near Heat Advisory level heat indices.

The warm and humid air will also create modest CAPE values in the
1500-2500 J/kg range but with a cap at the top of the boundary
layer, coverage should be fairly low even with the strong
instability and PWATs well into the 90th percentile. Any
thunderstorm that forms will be slow moving and capable of producing
localized flooding.

&&

.AVIATION (00Z TAF Issuance)...
Issued at 621 PM EDT Tue Jun 11 2024

Impacts:

- No noteworthy impacts

Discussion:

Light northwesterly flow will switch to light southerly. During the
transition, some variability in wind direction can be expected. VFR
conditions will prevail.


&&

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

$$

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