Forecast Discussions mentioning any of "ACARS" "MDCRS" "AIRCRAFT" "TAMDAR" "AMDAR" "WVSS" received at GSD on 03/01/24

Area Forecast Discussion

National Weather Service Indianapolis IN

 1000 PM EST Thu Feb 29 2024

.Key Messages...

- Seasonal temperatures through Friday.
- A few snowflakes or rain/snow mix possible early Friday, then
  scattered rain showers and/or drizzle possible into Friday
  evening.
- Much warmer for the weekend, with 70s possible by Sunday into
  Monday.
- Chance for rain showers returns Monday onward, with thunderstorms
  possible late Monday night into Tuesday evening.

&&

.Forecast Update...
Issued at 959 PM EST Thu Feb 29 2024

Following a sunny but slightly subnormal leap day, tonight will
exhibit a seasonable transition into March.  Broad high pressure
sliding east across the Midwest will continue to promote rather
light south-southeasterly flow...while high clouds slowly thicken
ahead of the next, rather weak disturbance approaching from the
southern Plains. These features will allow temperatures to drop into
the upper 20s to around 30F.

Guidance is continuing to show chances of precipitation entering far
southwestern portions of the CWA by 12z...although what forcing and
associated virga that make it into Indiana will more likely saturate
lower levels than produce widespread or appreciable precipitation.
Can`t rule out a few flurries or isolated mixed precipitation
towards dawn...although suspect any minor impacts would be isolated
and very brief after sunrise.

&&

.Short Term...(This evening through Friday)
Issued at 252 PM EST Thu Feb 29 2024

As surface high pressure steadily departs the area this afternoon,
temperatures have recovered a bit to near normal across central
Indiana, with highs likely to hit the 40s most everywhere. Winds
will more southerly/southeasterly tonight as the high exits, though
will remain light throughout.

The entirety of the profile is quite dry today, per ACARS soundings,
and the low levels are extremely dry, with surface dewpoint
depressions of 25-30+ degrees common, and this low level dryness
will continue into tonight and early Friday - forecast soundings
across the board depict a persistently parched low-mid level airmass.

A fairly compact upper level shortwave trough will swing through the
Great Lakes Friday into Friday night, but the surface reflection of
this system will be weak and well to the south along with the
primary low level baroclinic zone. As a result, moisture transport
into the region will be somewhat disjointed, with mid and upper
level moisture arriving ahead of the upper level wave, and the low
levels relying to a significant degree upon evaporative processes to
saturate. Additionally, the upper levels begin to dry out fairly
quickly just after the low levels are able to moisten up. Have
capped PoPs on Friday at chance as a result, and any precipitation
that does occur should be quite light, though moist low levels
continuing into Friday evening will likely allow for clouds and some
lingering drizzle.

Precipitation early Friday, should it occur, may fall in the form of
a few snowflakes or a rain/snow mix, but little to no impact is
expected - more than likely, early precipitation will be in the form
of virga as the aforementioned evaporative processes take place. A
lack of a significant warm layer aloft should prevent any freezing
precipitation.

Despite increasing high cloud overnight, light winds and the very
dry low levels should allow for good diurnal cooling, and have cut
blend numbers by a few degrees as a result, closer to a MOS
consensus and nearer the low side of the guidance envelope. These
same increasing and lowering clouds, as well as scattered showers,
will limit diurnal heating on Friday, and have also cut blend
numbers similarly for highs.

&&

.Long Term...(Friday night through Thursday)
Issued at 252 PM EST Thu Feb 29 2024

Friday night through Sunday night...

Isolated light showers may be ongoing early Friday evening as a
shortwave trough will be directly overhead. The strongest forcing
should be well south and east of the area which keeps QPF amounts
light. Expect this upper level impulse to then quickly move out
during the evening with light showers tapering off. Increasing
subsidence aloft behind the departing system will keep low clouds
around through at least the morning on Saturday. Drier air should
then filter in during the afternoon promoting more sunshine. Both
ridging at the surface and aloft supports quiet weather conditions
over the weekend. The main story will be temperatures quickly
warming up thanks to increasing southerly flow. Highs near the mid
50s and low 60s Saturday are expected to warm into the upper 60s to
low 70s by Sunday. Breezy conditions are likely on Sunday due to a
strengthening surface pressure gradient.

Monday onward...

Look for increasing rain chances early next week as a cold front
associated with a developing surface low approaches. Ensemble
guidance is still not in good agreement which limits confidence in
exact details. However, increasing low-level theta-e advection ahead
of the cold front combined with increasing large scale ascent will
likely support widespread precipitation. Weak destabilization is
expected ahead of the approaching front which could support a few
thunderstorms. Timing of the front remains uncertain and some
guidance shows the front could stall near the Ohio River late
Tuesday into Wednesday before eventually moving back north as a warm
front later in the week. There is likely to be a brief dry period
after the front pushes south, but will stick with a blended approach
of low rain chances through Thursday for now due to model ambiguity.
Widespread highs in the low 70s are expected Monday before
temperatures begin to cool down. Record high lows are possible on
Monday with temperatures in the low-mid 50s.

&&

.Aviation...(00Z TAF Issuance)
Issued at 642 PM EST Thu Feb 29 2024

Impacts:

- Ceilings quickly deteriorating Friday to low-MVFR around 17-19Z
- CIG drop continuing to IFR at KIND/KBMG around 19-21Z

Discussion:

VFR will continue to prevail tonight over central Indiana tonight as
the broad surface high pressure`s center shifts to east of the
region.  Winds generally sustained at 4-7KT will continue from
mainly SSE headings.

A weak disturbance will slowly cross the region Friday and into
Friday evening, bringing most notably quickly deteriorating ceilings,
from south to north...with low-MVFR stratus arriving 17-19Z...and
IFR expected to settle into KIND/KBMG during 19-21Z.

Modest visibility reductions to low-VFR levels are possible under
VCSH/mist after 15z Friday, although confidence in VIS reduction too
low to include in any TAF.  KIND/KBMG may see briefly scattered
-SHRA Friday afternoon...with all VCSH expected to depart eastward
by 23z.  Patchy drizzle is also possible at KIND Friday evening.

Winds should exhibit a subtle increase during the day Friday...
sustained up to 10KT during the afternoon, continuing from the SSE.

&&

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

$$

Update...AGM
Short Term...Nield
Long Term...Melo
Aviation...AGM