Forecast Discussions mentioning any of
"ACARS" "MDCRS" "AIRCRAFT" "TAMDAR" "AMDAR" "WVSS" received at GSD on 10/23/22
Area Forecast Discussion
National Weather Service Indianapolis IN
1152 PM EDT Sat Oct 22 2022
...Updated Aviation Discussion...
.Forecast Update...
Issued at 937 PM EDT Sat Oct 22 2022
High clouds along with some mid clouds will continue to move across
central Indiana overnight as an upper trough moves nearby. Adjusted
sky cover based on latest trends seen on satellite and in
observations. Not expecting any sprinkles from the mid clouds as the
atmosphere remains dry in the lower levels.
Temperatures look on track given the expected conditions, so made no
changes to low temperatures.
&&
.Short Term...(This evening through Sunday)
Issued at 255 PM EDT Sat Oct 22 2022
* Well above average temperatures persist through the weekend
* Dry and breezy conditions accompany the warmth
.Synopsis...
Deep trough diving southeast across the West phases with the
subtropical jet resulting in a rapidly deepening surface low across
the Northern Plains by Sunday. Ahead of the developing system, upper
ridging builds across the Midwest as the subtropical jet surges
north allowing a more moist and warm airmass to spread into the
region.
This evening and Tonight...
Current satellite imagery and surface analysis show mainly dry
conditions across the region with a few high clouds moving in from
the southwest. Left exit region of the subtropical jet is currently
located around SE KS/ SW MO placing the midwest in an area of upper
level divergence and enhanced lift. Moist air advection aloft
combined with a favorable region for lift has result in high clouds
over the Ohio Valley and Indiana this afternoon and evening. These
clouds are forecast to push northward tonight then clear out
tomorrow morning. Only impact from them will likely be keeping low
temperatures from dropping much overnight.
Still keeping an eye on RH values this afternoon as 18z IND ACARS
soundings still shows a very dry layer around and under 2 km with
dew points as low as -25C. The inversion this afternoon has already
broken and mixing is occurring up to around 0.5 km, just under the
very dry layer above. With continued warming, there is a chance low
level lapse rates may steepen enough to break the subsidence
inversion above it and allow much drier air to reach the ground. If
this does happen, low RH values in the 30s would only be present for
a few hours during peak heating this afternoon and evening. Keeping
the SPS for elevated fire risk out through the evening. Do not
believe conditions will warrant an upgrade to a Red Flag Warning.
With such a tight pressure gradient, winds may remain elevated
overnight around 4 to 10 kts which will also prevent temperatures
from falling too much. Overnight lows in the upper 50s to near 60
will make it feel more like summer than late October!
.Tomorrow...
Subtropical jet begins to lift north as it phases with the trough
out west. The best warm and moist air advection remains to the west
as the core of the strong 35 to 50 kt low level jet runs along the
Mississippi River in MO and IL and points northward; however still
expect some increase in both temperatures and humidity on Sunday
locally. Tight southerly pressure gradient will result in another
breezy afternoon with steep low level lapse rates likely mixing down
higher gusts of 20 to 25 kts down to the surface. With 850 mb
temperatures around 11-13C and abundant PBL heating and mixing, high
temperatures approaching 80 degrees is likely for a few locations
around Central Indiana. RAP forecast soundings show mixing heights
upwards of 1 to 1.5 km tomorrow and with modest moisture advection
through the entire column, fire weather conditions will be limited
as Min RH values should not fall below the mid 30s to around 40
percent range. Still will keep an eye on forecast and ACARS
soundings as guidance has had a moist bias lately this month.
Expect mid and high level clouds to begin advecting into the region
from the south and west late Sunday afternoon into Sunday evening
ahead of the developing system in the Plains begins and as the
subtropical jet pushes northward. By late Sunday afternoon, the
strong low level jet begins to inch closer to the region increasing
moisture advection through the column. That combined with weak
isentropic lift should lead mid and higher clouds moving into the
region. Expect this trend to persist into Monday.
Overall a warm, dry, and breezy end to the weekend for Central
Indiana
&&
.Long Term...(Sunday night through Saturday)
Issued at 255 PM EDT Sat Oct 22 2022
* Above-average temperatures continue into next week
* Breezy and dry, with elevated but non-critical fire weather
conditions possible through Monday
* Increasing confidence for rain Tuesday into Wednesday
Saturday Night into Monday
Strong southerly flow ahead of a deepening west coast trough will
continue through the weekend. A persistent LLJ between 40-50kts at
850mb has dramatically increased temperatures over the past couple
days. Additionally, low-level moisture advection has been
increasing. Very dry surface fuels, between 5-6 percent, are present
across most of the region. With no rain expected, dry surface fuels
should persist into next week. A tight surface pressure gradient and
diurnal mixing will create windy conditions at times. Enhanced
downward momentum transfer during peak mixing may tap into the LLJ,
producing gusty winds at times. Wind gusts between 20-30mph are
possible at times through Monday, mainly during the afternoon hours.
Winds may gradually gain a slight southeasterly component on
Sunday which could allow some dry air to advect into the area.
Combined with the warm temperatures, relative humidities drop to
as low as 30-35 percent at times. Therefore, elevated fire
weather conditions are possible through Monday. Critical fire
weather thresholds are not currently anticipated, due to increase
low-level moisture advection preventing excessively dry RH
values.
High-level moisture advection should also increase ahead of the
western trough. Intervals of cirrus clouds are likely until thicker
cloud cover arrives later on Monday. High temperatures each day
should top out in the mid to upper 70s, with a few locations
reaching 80. A tight surface pressure gradient will maintain breezy
conditions into the night, preventing low temps from dropping beyond
the mid 50s.
Tuesday into Wednesday
The deep western trough is modeled to reach its peak strength midday
Sunday. After this, guidance splits the trough into two distinct
pieces of energy, with one racing off the the northeast into Canada
and another lagging behind in the four-corners region. The northern
piece should pass well to our northwest, and any precip associated
with this feature should not affect Indiana. The southern piece of
energy, however, will eventually bring impactful weather to our
state.
To the southwest of the deep trough, a cut-off low is located
off the coast of Baja California. As this feature moves
northeastward, guidance phases it with the southern piece of energy.
Cyclogenesis then begins across the southern Great Plains on Monday.
Confidence lowers after this point, but has generally been
increasing as guidance comes into agreement on the track and timing
of the low. The northern jet stream reconnects over the US-Canadian
border and the phased southern system becomes partially cut off.
This may limit the amount of strengthening the system is capable of
before reaching Indiana. Peak intensity occurs just upstream,
somewhere over Missouri or southern Illinois, with weakening
thereafter. Precipitation amounts and thunderstorm probabilities
will depend on timing and how strong the system is when it arrives.
Thursday through Saturday
After the passage of Tuesday`s system, temperatures begin to warm
once again. With the northern branch of the jet stream reestablished
north of the departing system, broad ridging and warm air advection
quickly resumes on Thursday. Temperatures rebound into 60s to close
out the week along with dry weather. Ensemble guidance hints at
another trough entering the Plains on Friday in a split flow
pattern, which could bring rain back into the forecast by Saturday.
Chance PoPs have been added though confidence is quite low.
&&
.Aviation...(06Z TAF Issuance)
Issued at 1152 PM EDT Sat Oct 22 2022
Impacts:
- Winds 160-180 degrees will increase to 12 to 17 knots with gusts
over 20 knots after 14z
- Non-convective low level wind shear possible at KLAF and KHUF 12z-
14z
Discussion:
Status quo regarding breezy afternoon southerly winds that will gust
over 20 knots by mid morning and near 30 knots in the afternoon,
mainly at LAF. In addition, persistent dry column leads to very high
confidence in VFR flying conditions with just passing cirrus and
mainly overnight as an upper trough swings through.
Non-convective low level wind shear is possible for a few hours
toward daybreak, mainly at KLAF and KHUF.
&&
.IND WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
Update...50
Short Term...CM
Long Term...Eckhoff
Aviation...MK