Forecast Discussions mentioning any of "ACARS" "MDCRS" "AIRCRAFT" "TAMDAR" "AMDAR" "WVSS" received at GSD on 11/09/23

Area Forecast Discussion

National Weather Service Indianapolis IN

 937 PM EST Wed Nov 8 2023

.Key Messages...

- Light showers will continue tonight with highest coverage across
  the northern counties
- Seasonable and dry weather Thursday through Tuesday
- Early indications of anomalous warmth returning late next week

&&

.Forecast Update...
Issued at 937 PM EST Wed Nov 8 2023

Some showers have developed as expected along a cold front that was
not far west of central Indiana this evening. Adjusted timing and
coverage of PoPs based on the latest trends seen on radar.

Surface convergence is decent with the front, and there is some weak
instability that the showers are moving into. This may increase the
coverage of showers a bit. However, the instability is just too weak
to expect any thunder.

Will continue to keep chance to low end likely PoPs into the
overnight as the front marches east.

Some wind gusts up to 30 mph will continue along and for a while
behind the front.

Adjusted hourly temperatures as needed but made no significant
changes to overnight lows with colder air moving in quickly behind
the front.

&&

.Short Term...(This evening through Thursday)
Issued at 125 PM EST Wed Nov 8 2023

Rest of Today.

Focus for the rest of the day will be on the record to near record
heat across central Indiana and gusty winds. As of early this
afternoon, portions of southern Indiana had already climbed in the
80s as an extremely warm EML which originated from the Southern
Plains where surface temperatures were in the 90s earlier this week
continues to advect into the area. ACARs soundings show 850mb temps
at around 16C which is almost 20C above normal for this time of the
year.  RH values near the bottom of the EML are around 100 percent
which is contributing to the cu field across central Indiana.
Surface temperatures have climbed into the mid to upper 70s for all
but the far northern counties with low 80s in the southwest where
cloud coverage has been lowest.

Wind gusts have begun to ramp up which indicates that the mixing
layer has begun to deepen but the 850mb cap should limit the maximum
gusts to around 30kts. Expect that wind gusts will continue to
slowly ramp up through 22Z before gradually relaxing. There is a low
probability potential for a quick burst of winds in excess of 30kts
between 22Z and 02Z as the 850mb winds approach 45kts, but mixing
will become much less efficient by due to the cooling surface
temperatures.

Tonight.

Focus tonight then shifts to the incoming rain as a cold front
passes through central Indiana. The front is currently expected to
pass through from around 05Z to 09Z with best rain chances just
ahead of the front.  Model soundings show some limited elevated
instability but that instability is generally focused north of the
forecast area where there is a non-zero thunder potential.  Across
central Indiana the instability should remain too limited for even an
isolated rumble.

Thursday.

Temperatures behind the front will only fall to around normal for
this time of the year with the polar air remaining well into Canada.
Winds will remain somewhat elevated with the lingering pressure
gradients but expect that wind gusts should remain below 20 mph.
Skies will also briefly clear during the daytime hours before high
level clouds return late into the day.

&&

.Long Term...(Thursday night through Wednesday)
Issued at 125 PM EST Wed Nov 8 2023

Generally a tranquil weather pattern for the long term with a return
to near normal temperatures in the post-frontal air mass Friday. A
shortwave trough will pass to our north tomorrow but the
deeper/anomalous moisture remains associated with the subtropical
branch and thus rainfall should be confined to near/south of the
Ohio River. We may see high level clouds on the northern edge of
remnant frontal slope, however we think it is quite a stretch for
measurable rain to make it northward into our southern tier of
counties.

In fact, for the entire long term period precipitable water will be
neutral to negative, so any weak perturbations in the flow aloft
will be ineffective at generating precipitation. By the middle of
next week we will see rising midlevel heights and a warming trend.
Blended starting point appears to have a cool bias and we have
nudged toward raw guidance the middle of next week.

For the 8-14 Day period: There is a strong and consistent signal in
medium range ensemble placement and magnitude of significant ridging
across the Plains by the latter half of next week. This will nudge
into our region with time bringing anomalous warmth. The signal for
precipitation during this period is less consistent at this time,
and if happened would probably be limited to a closed/cut off low in
a blocking pattern that some medium-range models show.

&&

.Aviation...(00Z TAF Issuance)
Issued at 613 PM EST Wed Nov 8 2023

Impacts:

* Low level wind shear this evening even with some gusts at the
  surface
* Pronounced wind shift to northwest by 06Z
* MVFR ceilings developing this evening and continuing into Thursday
  morning

Discussion:

Wind gusts will come down some for the early part of the TAF, but
strong winds aloft will create low level wind shear conditions for
the first few hours of the period. As a cold front moves through mid
to late evening, winds will shift to northwest and gust for a bit
longer.

MVFR ceilings and scattered showers will develop this evening.
Showers will diminish by early overnight, but MVFR ceilings will
persist into Thursday morning. Some uncertainty remains on when
these will break up, but VFR is expected during the afternoon.


&&

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

$$

Update...50
Short Term...White
Long Term...BRB
Aviation...50