Forecast Discussions mentioning any of "ACARS" "MDCRS" "AIRCRAFT" "TAMDAR" "AMDAR" "WVSS" received at GSD on 09/01/22

Area Forecast Discussion

National Weather Service Indianapolis IN

 1112 PM EDT Wed Aug 31 2022

...Updated Aviation Discussion...

.Forecast Update...
Issued at 919 PM EDT Wed Aug 31 2022

High pressure, clear skies and light to calm winds will result in
ideal radiational cooling tonight which should allow temperatures to
bottom out in the upper 50s to lower 60s. Patchy fog is possible
overnight to just after daybreak as was the case last night. Chances
may be even a little higher tonight as dew points are a bit higher
in the 60s at some many locations. That said, BUFKIT was showing
very dry just off the surface, so any fog should be shallow and
brief.

&&

.Short Term...(This evening through Thursday night)
Issued at 237 PM EDT Wed Aug 31 2022

...Seasonably warm and dry conditions through the end of the week...

...Increasing clouds Thursday into Thursday night...

...Tonight...

Benign weather is expected to persist through the short term as an
surface high pressure tracks through the region. Current satellite
imagery this afternoon shows clear skies across the entire Wabash
Valley as surface high pressure sits just west of the region over
Missouri. Northwest flow on the east side of the high has ushered in
a much drier airmass with dew points falling into the low 50s.
Strong subsidence under the high and a very dry column as seen on
the 18z IND ACARS sounding has kept cumulus clouds from developing
despite afternoon mixing. High pressure moves directly overhead
tonight keeping skies mainly clear and creating optimal conditions
for radiational cooling. Isolated areas of fog may develop overnight
as temperatures fall towards forecasted dew points; however
confidence remains low on any fog as the boundary layer has dried
out significantly today. Keeping any mention of fog out of the
official forecast, but will keep a close eye to obs and satellite
tonight in case a few areas do form.

...Thursday...

The weather pattern begins to change on Thursday, but tranquil
weather is still in the forecast for the entire region. Weak upper
level troughing begins to develop in the Central Plains tomorrow as
ridging strengthens over the west. Moist air is drawn northward in
the upper levels as flow becomes southwesterly aloft in response to
the deepening trough to the west. Therefore, expect high clouds to
increase through the day from south to north across Indiana. Despite
an increase in clouds, hot and dry weather will still persist as the
surface high pressure tracking east across the Ohio Valley remains
the dominant weather influence. Temperatures aloft around 850mb warm
to around 15-16C Thursday as the low level ridge axis pushes east,
supporting surface high temperatures in the mid 80s. If upper level
clouds move in too fast or become thick, high temperatures may be a
couple degrees cooler than forecasted highs. Upper level clouds are
forecast to continue streaming into the region from the southwest
Thursday night into Friday morning, which will likely keep low
temperatures elevated overnight in the mid to upper 60s rather than
falling to upper 50s like on Wednesday night.

&&

.Long Term...(Friday through Wednesday)
Issued at 237 PM EDT Wed Aug 31 2022

After a dry and pleasant start to the extended as high pressure
currently across the region continues to influence weather...expect
a gradual shift back to a warmer and more humid airmass for the
holiday weekend with the potential for isolated diurnally driven
afternoon convection as deeper moisture returns to the Ohio Valley
and interacts with a weak remnant frontal boundary.

Zonal flow will develop as the upper low over James bay this
afternoon will retreat to the north through the second half of the
work week. There is growing confidence in a weakness in the upper
flow regime developing however by Friday in between a strengthening
upper ridge over the Intermountain West and expanding ridging over
the western Atlantic. This feature now is likely to become at least
an indirect factor for the Ohio Valley perhaps as early as Saturday
as the weakness aloft in the form of a weak upper low lifts into the
area. While the high pressure will remain close enough to maintain
dry and seasonable weather Friday...return southerly flow will start
to advect deeper Gulf moisture north into the Ohio Valley for the
weekend. The arrival of the low level moisture plume Saturday will
manifest with a noticeably more humid airmass and temperatures
pushing 90 degrees.

The weakness aloft combined with a moist and modestly unstable
airmass will likely bring a threat for isolated diurnally driven
convection during the afternoon and evening on Saturday...with the
arrival of a weak frontal boundary drifting into the lower Great
Lakes by Sunday contributing to additional threats for isolated
showers and storms during peak heating Sunday and Monday. Extended
model guidance remains uncertain on specifically where the frontal
boundary lays out before stalling early next week...but it will be
in a close enough proximity to serve as an influence for potential
convection. In the absence of more substantial forcing aloft and
with virtually no BL shear present...convection is likely to remain
largely isolated and of a pulse subsevere intensity through the
holiday weekend. Main impacts from any convection would be brief and
localized heavy rainfall and perhaps gusty winds as cores collapse.

Warm and humid conditions will persist into early next week with
highs in the mid and upper 80s through Tuesday as the weakness aloft
retrogrades back into the central Plains and diminishes with broad
ridging reestablishing over the region.

&&

.Aviation...(06Z TAF Issuance)
Issued at 1112 PM EDT Wed Aug 31 2022

Impacts:

- VFR FLYING conditions expected to dominate the TAF period

- Small chance of very brief IFR fog at the smaller airports
  09z-12z

Discussion:

High pressure and a dry column will provide VFR flying conditions
through the TAF period with increase in high level moisture
supportive of some cirrus by this morning . Would not rule out brief
shallow IFR fog toward and through daybreak at the smaller airports,
as was the case last night, as light to calm winds support radiative
cooling.

&&

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

$$

Update...MK
Short Term...CM
Long Term...Ryan
Aviation...MK