Forecast Discussions mentioning any of
"ACARS" "MDCRS" "AIRCRAFT" "TAMDAR" "AMDAR" "WVSS" received at GSD on 03/28/24
Area Forecast Discussion
National Weather Service Indianapolis IN
932 PM EDT Wed Mar 27 2024
.KEY MESSAGES...
- Clear skies with sub-freezing temperatures tonight
- Quiet weather Thursday
- Wetter weather appears to be on the horizon for this weekend
into next week.
&&
.FORECAST UPDATE...
Issued at 932 PM EDT Wed Mar 27 2024
Forecast is in good shape this evening. Skies were clear and winds
were diminishing.
Satellite shows some mid clouds across western and central Illinois,
but these continue to dissipate as they move east into a dry
atmosphere (as can be seen in latest IND ACARS sounding). A few of
these may eventually make it into central Indiana, but skies will
still remain mostly clear.
Temperatures will continue to fall with the lessening winds and
mostly clear skies. Given these conditions and current dewpoints,
nudged down low temperatures for favored cold spots.
&&
.SHORT TERM (This evening through Thursday)...
Issued at 322 PM EDT Wed Mar 27 2024
Tonight.
Chilly conditions with another potential hard freeze tonight with
efficient radiational cooling conditions expected. As of early
this afternoon the stratus deck that has been persistent for the
last 18 hours continues to slowly erode with expectations that skies
will be mostly clear by later this evening. These mostly cloudy skies
will combine with near calm winds as pressure gradients drop to
near 0 and dry surface air with dewpoints in the low to mid 20s.
Low to mid level subsidence will also be maximized during the late
overnight hours above the inversion layer.
Thursday.
Dry and quiet weather will continue into Thursday with plenty of sun
during the afternoon hours bringing warmer temperatures to central
Indiana. Surface flow will remain westerly through the day which
will limit the warm air advection, but think that with the abundant
sunshine through most of the day that highs into the 50s to near 60
look likely. Will have to keep an eye on a subtle area of
saturation at the top of the boundary layer for the potential of
transient cloud cover during the late morning and afternoon hours.
This combined with diurnal heating may end up keeping cloud cover
more widespread than currently forecast. With the relatively deep
mixing up to around 5000-6000 feet, occasional wind gusts to 25 mph
look likely during peak heating.
&&
.LONG TERM (Thursday night through Wednesday)...
Issued at 322 PM EDT Wed Mar 27 2024
Friday...
Upper-level height rises are expected to promote the retention of
surface high pressure through the beginning of the period as a
trough lifts out of the region. Towards the surface, warm air
advection is expected to quickly begin to bring warmer air in from
the southwest late Friday. The retreating cold air mass will act
as a pseudo- lifting mechanism to where some light, frontogenetic
precipitation will be possible throughout the afternoon/evening.
Forecast soundings from the northern portion of the CWA show a
shallow layer of weak lift and high RH from 850 - 700 mb, so any
precipitation that makes it to the surface will be light. Any
accumulations will be a trace at most. Into Friday/Saturday night,
this region of lift will move to our east and leave the region.
Residual moisture will still persist above 900 mb, and should
continue to build with support from southwesterly moisture
transport. Expect building clouds with highs in the 60s and virga
plus some sprinkles in our northern counties.
Saturday...
By this point in the forecast, a modest 700 - 300 mb jet streak is
progged to begin exiting the rockies over the plains, advecting into
the midwest by midnight Saturday. The core of this streak is well
advertised to be to our south, which will bring the left exit region
through the region into the morning. A surface low deepens in
response over the MS river in IA/IL at this time, enhancing
isentropic ascent over northern IL/IN into early Saturday morning. A
decent group of long and medium range models (GFS/ECMWF/GEFS/NBM)
show swaths of precipitation north of the I-74 corridor with storm
total QPF (00z Sat - 00z Sun) anywhere from .1" - .3" as you move
north. Most precipitation should exit the region to the east by 18z
Saturday with a quick cold-frontal passage. Wind gusts into the mid
20 knot range are also possible during the day.
Due to a steady axis of warm air advection, temperatures should only
drop into the upper 40s and low 50s by Saturday morning. With
regards to high temperatures, the NBM seemed way too high given
expected cloud cover and precipitation. So, we opted to reduce the
max temperature by a few degrees with the 25th percentile with highs
in the upper 60s. To note, however, max temperatures will likely
occur earlier in the afternoon in tandem with a frontal passage from
the north, from which point temperatures will begin to drop into the
evening hours with lows in the 40s and 50s into Sunday.
Sunday through Wednesday...
The amplification of the mid-latitude jet stream appears likely over
the eastern CONUS beginning Sunday as a longer-wave trough digs into
the west coast. Downstream of this feature, ridge amplification
remains relatively constant with a plume of Pacific moisture
overriding southerly warm advection from the Gulf of Mexico. At the
same time, the Saturday cold front will stall over central IN, and
with the southerly advection and a deepening lee surface trough in
CO/KS, there is support for this frontal zone to stall and
transition back into a warm front by Monday. Therefore, additional
precipitation is periodically expected starting Sunday through
Wednesday as the upper-level troughing exits the Rockies and
traverses the region.
At this time, there is too much uncertainty in the duration
and intensity of any precipitation episodes to give accurate
rainfall amounts. There is some support for convection from CIPS
guidance and the presence of relatively high surface moisture +
bulk shear overlap. But again, by this point we are discussing
days 5-7 in the long term period and normal long-range forecast
caveats such as location, timing, and amplitude, are always
applicable that might influence the juxtaposition of convection-
allowing features.
&&
.AVIATION (00Z TAF Issuance)...
Issued at 656 PM EDT Wed Mar 27 2024
Impacts:
- Wind gusts around 20kt Thursday afternoon
Discussion:
VFR conditions are expected through the period. There will be some
passing mid clouds at times, especially on Thursday.
Winds will diminish this evening, but will increase in speed on
Thursday. Gusts around 20kt will return Thursday afternoon,
especially after 18Z.
&&
.IND WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
UPDATE...50
SHORT TERM...White
LONG TERM...Nield/JAB
AVIATION...50