Forecast Discussions mentioning any of "ACARS" "MDCRS" "AIRCRAFT" "TAMDAR" "AMDAR" "WVSS" received at GSD on 06/20/22

Area Forecast Discussion

National Weather Service Indianapolis IN

 1116 PM EDT Sun Jun 19 2022

...Updated Aviation Discussion...

.Forecast Update...
Issued at 956 PM EDT Sun Jun 19 2022

Surface analysis this evening shows strong high pressure in place
over southern OH and northern KY with a ridge axis extending north
across the Great Lakes. GOES16 shows high clouds over the Great
Lakes associated with an embedded wave within the upper flow riding
the ridge. Subsidence still remains in place across Central Indiana,
with the protective ridge in place aloft. Water vapor imagery still
shows the upper ridge axis west of Indiana, close to the Mississippi
river valley. Dew point temps across the forecast area remained
mainly in the upper 40s and lower 50s.

No major changes to the ongoing forecast. The high cloud approaching
on satellite will remain mainly east of much of the forecast area
while subsidence remains in place across Central Indiana. The
surface high will remain the dominant feature as it slowly drifts
east and southerly surface flow begins on Monday morning. Thus will
continue mostly clear skies overnight.

&&

.Short Term...(This evening through Monday night)
Issued at 256 PM EDT Sun Jun 19 2022

Soak up the beautiful weather today before heat returns tomorrow.
Aloft, a blocked upper high, the same high that brought the heat
last week, will slowly expand and inch into the region. Meanwhile, a
surface high that is currently over the Ohio Valley will slowly push
southeasterly through the period, allowing for surface winds to be
variable through tonight before becoming more southerly by tomorrow.
The southerly flow will advect warmer air back into the region as
well as increase moisture with dew points going from the 40s today
to the 50s tomorrow. Both ACARS and model soundings show a very dry
layer at the mid levels today that is getting mixed down to the
surface, allowing for low RH values. Luckily winds are fairly light
and the fuel moisture is high enough that fire conditions are not
really a concern. Tomorrow`s high temperatures will be near 90 with
the WAA. Together, these high pressure systems will continue the
existence of dry air through the column in addition to plenty of
subsidence which will allow skies to remain mostly clear through the
period.

&&

.Long Term...(Tuesday through Sunday)
Issued at 256 PM EDT Sun Jun 19 2022

* Hot temperatures return
* Humidity and rain chances increase by Wednesday
* Drier to end the week

Tuesday

Hot weather is expected to return as a large upper-level ridge
begins to move eastward. Interestingly, this ridge is the same ridge
that brought last week`s heat. Instead of moving off to the east as
is typical, the ridge flattened while retrograding westward before
re-amplifying. Now with renewed strength, the ridge is heading back
in our direction.

Though it`s the same ridge that brought us the previous heat wave, a
few things will be different this time around. Namely, generally
lower humidity and soil moisture levels. These differences will
affect how hot we get and how hot it feels. Lower humidity and soil
moisture should allow air temperatures to rise more effectively.
Despite slightly cooler 850mb temps, the ambient air temps should be
comparable to last week. However, less humidity means lower apparent
temperatures, so it may not seem as hot as it did before. Max heat
indices should be near 100 throughout the CWA.

Wednesday and Thursday

Humidity levels should increase by Wednesday as the axis of the
ridge once again begins to flatten and retrograde southwestward.
Increasing southwesterly flow at the surface on the northwest edge
of the ridge should provide sufficient moisture advection to lift
dewpoints back into the 70s. Wednesday may be the overall hottest
day of the week, as the ridge will still be overhead despite the
initiation of a flattening trend. Additionally, the added humidity
may put max heat indices upwards of 105 degrees...which is near
advisory level. Will need to monitor trends over the next few days
regarding dangerous heat potential.

Concurrently, a weak cold front should be dropping south during the
day. While a majority of guidance depicts this front to some extent,
differences in timing and intensity will lead to lower confidence
regarding shower and thunderstorm potential. Northwest flow returns
in the post-front environment by Thursday, allowing temperatures and
dew points to drop a bit.

Friday through Sunday

Ensemble solutions begin to diverge late in the week, leading to
greater uncertainty regarding the evolution of the overall pattern.
A tendency towards more zonal flow is shown in both GFS and ECMWF
ensembles, with some slight ridging beforehand on Saturday. A shift
towards a generally flatter pattern makes sense, given the highly
amplified flow we currently find ourselves in. A flatter upper-level
pattern would open up the possibility for fast-moving shortwaves to
pass by, which would increase precip chances if timing is right. And
given the propensity for the jet stream to remain slightly north of
Indiana this time of the year...will maintain high temperatures in
the low 90s through the weekend and keep PoPs in the slight category
for now.

&&

.Aviation...(06Z TAF Issuance)
Issued at 1114 PM EDT Sun Jun 19 2022

IMPACTS:

* VFR Conditions are expected this TAF period.

DISCUSSION:

Little change to the ongoing and previous forecast.

High pressure across the Great Lakes, Indiana and Ohio will continue
to provide VFR conditions tonight and Monday. GOES16 shows some
clouds within the flow aloft over the Great Lakes. These clouds
should continue to subside overnight...resulting in just some
passing high cloud across the Taf sites. Forecast soundings on
Monday continue to show unreachable convective temperatures. As the
surface high sets up east of Indiana on Monday...southerly surface
winds are expected to develop. Continued subsidence under the high
will keep skies clear. No visibility issues expected.

&&

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

$$

Update...Puma
Short Term...KH
Long Term...Eckhoff
Aviation...Puma