Forecast Discussions mentioning any of "ACARS" "MDCRS" "AIRCRAFT" "TAMDAR" "AMDAR" "WVSS" received at GSD on 12/12/22

Area Forecast Discussion

National Weather Service Indianapolis IN

 938 PM EST Sun Dec 11 2022

.Forecast Update...
Issued at 937 PM EST Sun Dec 11 2022

* Overcast Overnight

Surface analysis this evening shows high pressure in place north of
the Great Lakes, spilling southward into the Ohio Valley. GOES16
shows extensive cloudiness across the forecast area and the region.
Lower level flow was light and from the north, but will become
easterly as the night progresses as the high pressure system to the
north builds.

Forecast soundings and time heights show little overall change
overnight. Saturation remains within the lower levels. Forecast
soundings continue to show a strong inversion in place overnight,
continuing to trap lower level moisture. Thus will continue with
cloudy skies overnight. Given the extensive cloud cover and very
minimal temperature advection have trended lows slightly warmer to
the middle 30s.

&&

.Short Term...(This evening through Monday)
Issued at 256 PM EST Sun Dec 11 2022

Mean ridging and surface high will move eastward into Indiana
through Monday, between two shortwave troughs. ACARS and model
soundings show a strong inversion with moist low level air mass
beneath, and there`s not much of a signal to displace this through
the short term. Surface winds will veer to northeasterly later
tonight and bring slightly deeper moisture into the area, likely
ensuring stratus remains. Depth could be minimally supportive of a
few sprinkles or very light drizzle this evening across northeast
portions of the area. If this occurs, amounts are expected to be non-
measurable.

There is some signal in models of drier air advecting in from the
northeast but the subsidence inversion remains sharp. It is likely
not enough dry advection to cause stratus to break tomorrow. Since
the midlevel ridge axis will remain west of us through the diurnal
mixing cycle tomorrow, and stratus will likely struggle to decrease,
temperatures will probably be similar to today. Our forecast is
round the 25th percentile of blended guidance since diabatic surface
heating will be minimal due to persistent stratus that models can be
too optimistic with in these patterns.

&&

.Long Term...(Monday night through Sunday)
Issued at 256 PM EST Sun Dec 11 2022

* Dry early in the work week with above normal temperatures through
  mid week.

* Widespread soaking rainfall mid week, particularly Tuesday night
  into Wednesday.

* Lingering rain and/or snow showers possible late in the week as
  temperatures plummet.

Story remains much the same as the last several days, as models show
an amplified ridge across the area early in the work week, with
rapid lee cyclogenesis occurring east of the Rockies as a massive
closed low moves across the mountains. This low will be the primary
weather maker throughout the long term.

This low will weaken and slow as it occludes and moves eastward,
with a warm conveyor belt aloft along the occlusion moving through
the area Tuesday night into Wednesday, promoting a widespread
soaking rainfall. There are some growing signals that rainfall may
be a bit less than anticipated earlier as the area becomes isolated
along the developing occlusion between the richer low level moisture
south and the stronger mesoscale forcing to our northwest, but
should still see at least a widespread light soaking rain.

Rainfall chances will linger into early Thursday as the occlusion
slows and a possible secondary low forms at the triple point
somewhere over the Midwest. Once this secondary low and the surface
front pass, a brief dry period is expected before forcing associated
with disturbances pivoting around the larger upper low move through
the region late in the week. Temperatures will have dropped
significantly by this point with the surface boundary passage, and
any precipitation late in the work week will likely be in the form
of snow showers. Significant accumulations, if any, do not appear
likely at the moment. As next weekend begins, much drier air in
addition to colder conditions should keep a cap on any precip
despite the ongoing cyclonic flow, although flurries may occur at
times as often happens during cyclonic flow in the cool season.

Models continue to advertise an extended cold stretch beyond the 7
day period that may last into the holidays or beyond.

&&

.Aviation...(00Z TAF Issuance)
Issued at 559 PM EST Sun Dec 11 2022

Impacts:

* MVFR ceilings expected throughout the period

Discussion:

Strong...broad and cold high pressure in place over Ontario
continues to influence the weather across the Ohio Valley with cool
and moist and dirty easterly flow. GOES16 shows abundant cloud cover
across the region. Forecast soundings and time heights continue to
show trapped lower level moisture across the area. This is shown to
persist tonight and again into Monday. Thus will continue with MVFR
through the TAF period as no trigger is apparent to bring about
clearing.


&&

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

$$

Update...Puma
Short Term...BRB
Long Term...Nield
Aviation...Puma