Forecast Discussions mentioning any of "ACARS" "MDCRS" "AIRCRAFT" "TAMDAR" "AMDAR" "WVSS" received at GSD on 11/23/22

Area Forecast Discussion

National Weather Service Indianapolis IN

 1004 PM EST Tue Nov 22 2022

.Forecast Update...
Issued at 1002 PM EST Tue Nov 22 2022

Looking at the latest observations this evening, temperatures appear
to be highly dependent on topography and local wind conditions.
Readings from near 30 to around 40 degrees were common across the
area. Large differences in temperature across short distances were
apparent as well, with 5 to 10 degree variations within 10 or so
miles. Made slight adjustments given the current obs and continued
stabilization of the boundary layer, clear skies, and decreasing
winds. Kept low temperatures largely the same for most locations,
but added weight to hi-res models such as the HRRR which seem to
have a better grasp on the finer details seen in obs. Adding more
weight to the hi-res guidance allows forecast temps in features
such as river valleys to be a tad cooler than surrounding areas.
Vice versa for slightly elevated areas. Such adjustments should
help better capture the localized variability, as is common under
temperature patterns driven primarily by radiational cooling.
Aside from that, sky and wind grids look good with no changes
made.

&&

.Short Term...(This evening through Wednesday)
Issued at 250 PM EST Tue Nov 22 2022

* Warming trend continues through midweek with highs nearing 60F

* Very dry conditions persist

.This evening and tonight...

Current surface analysis shows surface high pressure stretching from
Texas towards the Mid Atlantic with lower pressure across the
Northern Plains and along the Front range. Clear skies are found
across the entire state as a very dry atmosphere and subsidence
under the high are keeping any clouds and precipitation away. 18z
IND ACARS soundings shows a very similar picture this afternoon as
the past few days with a shallow mixed layer near the surface
bringing down slightly drier air and stronger winds aloft. Today,
the LLJ is much weaker than yesterday resulting in sustained winds
only around 10-15 kts with gusts remaining under 20 kts so far. With
such a dry environment, temperatures have soared with ample sunshine
well above NBM 90th percentile high. Have continued to bump highs up
into the mid and even upper 50s across the region for this afternoon
and evening.

Expect temperatures to plummet once again tonight as conditions will
be conducive for radiational cooling to take place. Despite the
center of the high south and east of the region, the pressure
gradient is still weak enough for winds to relax and even go calm in
a few wind sheltered areas. With dew points in the lower 20s this
afternoon, would not be surprised to see many areas reach the mid to
upper 20s by tomorrow morning. Lower 30s likely around the Indy
Metro due to the urban heat island.

.Wednesday...

Very similar synoptic set up tomorrow with high pressure remaining
across the Mid Atlantic states and low pressure continuing to
develop across the western Plains in response to a deepening upper
trough. Southerly flow continues to slowly advect a warmer airmass
into the region as highs have been a few degrees warmer than the
previous day each day this week. With increasing upper heights and
temperatures aloft at 850mb rising from around 2C today to up to 6C
tomorrow, max temperatures will likely be pushing 60 degrees,
especially in known warmer areas such as the Indy Metro. Forecast
soundings show mixing heights up around 2-3 kft, so expect dry air
and stronger winds to mix down to the surface again during peak
heating of the day. With weak moist air advection taking place with
persistent southerly flow, dew points and RH will be slightly higher
than the previous day. Still, with such dry conditions at the
surface, expect RH values to significantly drop during the afternoon
making for a slightly elevated fire threat. Winds are not expected
to be strong with max gusts around 10-15 kts according to forecast
soundings.

Did similar forecast techniques as the past few days since it has
been verifying well and the pattern is remaining largely the same.
For max temperatures and winds going above NBM 90th percentile,
while trending towards the lowest end of guidance for Dew Point and
RH values due to afternoon mixing and very dry antecedent
conditions.

&&

.Long Term...(Wednesday night through Tuesday)
Issued at 250 PM EST Tue Nov 22 2022

* Mild and Dry through Thanksgiving
* Rain Chances return late Thursday Night through Sunday

Thanksgiving...

A ridge axis over the Mountain West will progress eastward,
supported by moderate 850-750mb WAA within SW flow. This flow will
also provide some moisture return, with a saturating moisture
profile above 800mb. Thursday morning will still be rather dry with
mostly clear conditions outside of upper level cirrus within a
strong upper level jet. Clouds will fill in throughout the day as
the upper atmosphere saturates. The PBL should be well mixed with
the near surface layer remaining dry. This should promote efficient
warming, with a slight cap on the afternoon with increasing cloud
cover. Expect afternoon highs in the upper 50s to low 60s.

Thursday Night through Friday...

An upper level trough will near from the west/northwest Thursday
night. The main vorticity lobe in the trough apex will separate from
the polar jet, leaving a weakly forced upper to mid level trough
over the upper Midwest. Precipitation over the Tennessee Valley will
limit surface moisture return, but the upper to mid levels will be
saturated. A seeder feeder effect within weak ascent should be
enough for light rain to occur overnight. QPF will be marginal, with
current expectations of less than 0.20". The trough axis will exit
Friday morning, with increasing heights promoting large scale
subsidence by Friday afternoon. Temperatures will remain mild with
little to no CAA behind the trough.

Saturday and Sunday...

The aforementioned vort max displaced from the polar jet will
progress to the NE later this week within a strong subtropical jet
streak on its eastern flank. This will once again push warm air over
the Ohio Valley, keeping conditions mild even with sustained cloud
cover. As the upper level low pushes NW, surface cyclogenesis is
likely to occur to its NE, quickly occluding as the Dry Conveyor
Belt wraps around. This should place a vertically stacked low over
the Western Ohio Valley late Saturday into Saturday night. Surface
moisture return should be much more sufficient for this event, and
with strong ascent within CVA, bands of moderate rain will likely
form. This should lead to higher QPF within this event (0.5-1.0").
There is still a lot of uncertainty with the track of the closed
low, leading to a wide array of precipitation solutions both timing
and amounts. By Sunday night, the low should be out of the region,
with precipitation chances decreasing rapidly.

&&

.Aviation...(00Z TAF Issuance)
Issued at 618 PM EST Tue Nov 22 2022

Impacts:

* None

Discussion:

VFR conditions are expected through the TAF period at all terminals.
Broad surface high pressure to our southeast will allow winds to
retain a south-southwesterly component through tonight and most of
tomorrow. A decaying cold front approaching from the northwest will
cause the surface pressure gradient to weaken a bit, so lighter
winds are expected tomorrow compared to today. Nevertheless, some
occasional gusts to around 10kts are possible at times during the
afternoon. No sensible weather is expected with the weakening front,
but some high clouds may begin to stream in from the southwest after
about 21z. Winds remain light into Wednesday evening, but slowly
become southeasterly after 00z as the surface high moves to the
northeast.


&&

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

&&

$$

Update...Eckhoff
Short Term...CM
Long Term...Updike
Aviation...Eckhoff