040
FXUS63 KIND 221601
AFDIND

Area Forecast Discussion
National Weather Service Indianapolis IN
1101 AM EST Fri Nov 22 2024

.KEY MESSAGES...

- Cloudy and cold today.

- Light Rain showers possible along and east of a Kokomo to
  Indianapolis line.

- Clouds linger tonight.

- Warming trend this weekend with a chance of light rain Monday.

- Lower than normal forecast confidence the second half of next week
  with some wintry precipitation potential.

&&

.FORECAST UPDATE...
Issued at 847 AM EST Fri Nov 22 2024

25-35 knot fetch off Lake Michigan could bring a few showers in
across areas mainly near and east of Delphi, Indianapolis and
Rushville today. As the day goes on, this flow will become more
northwest which should confine any showers to far northeastern
sections. Hi-Res soundings, and wet bulb temperatures are supportive
of rain only as the precipitation type. Cyclonic flow around the
East Coast high and boundary layer moisture beneath a strong
inversion will keep the low clouds around across all of central
Indiana. Warm advection ahead of a Plains to Great Lakes thermal
ridge should allow temperatures to climb back into the 40s despite
the thick cloud canopy.

&&

.SHORT TERM (Today and tonight)...
Issued at 250 AM EST Fri Nov 22 2024

Synopsis:

Surface analysis early this morning shows deep low pressure in place
over CT/RI. This deep low was was providing cyclonic flow to much
of the eastern half of the country. Cold northerly surface flow
was in place across Central Indiana. Aloft, water vapor showed an
associated large and broad upper low over the middle Atlantic
States, also influencing the flow across the eastern half of the
country. GOES16 imagery shows cloudy skies across Indiana and much
of the region, with the clearing line being found across Eastern
MO and Central IA. Radar mosaics show isolated light showers
within the cyclonic flow across Central Indiana. Of note, a band
of Lake Effect showers was found over Lake Michigan pushing
southward. Temperatures across the area remained in the lower to
middle 30s.

Today -

Models suggest the upper low over the middle Atlantic states will
make slow progress northeast today, still influencing much of the
upper flow across Central Indiana. As the upper low does slide
eastward late in the day, weak ridging aloft over upper midwest will
begin to sag southward to our state. This will provide subsidence
and drying aloft. However forecast soundings suggest the lower
levels will remain saturated with, with cold air trapped beneath a
mid level inversion. Thus clouds will be expected to remain through
the day.  HRRR shows the lower level flow remaining northerly
through the day. This allows for some lake effect rain showers to
reach areas across northern Central Indiana, mainly along and east
of a IND-OKK line. HRRR suggests that as the day progresses, flow
across Central Indiana will become more northwesterly. This will
allow for a gradual west to east progression of these light
showers across OKK to AID and eventually toward MIE late in the
day. Forecast soundings today show enough warm air within the
lower levels that precip type should remain rain. Thus will try to
keep pops limited to that area.

Slight warm air advection from the north is expected today as the
cold core of air exits to the southeast. However, this should not
have an overly large impact on temperatures. Highs will reach the
lower to middle 40s under the clouds.

Tonight -

Models show ridging aloft continuing to build across Central
Indiana. This is expected to continue to provide subsidence and
drying aloft. Meanwhile forecast soundings and time heights continue
to suggest trapped lower level moisture across the forecast area.
Lower level flow remains northwest to westerly tonight, and there
does not appear to be enough of an impact to result in enough mixing
to break up the lower level cloudiness. Thus another cloudy night
will be expected.  Given the weak temperature advection, overnight
lows will be mainly in the upper 30s.

&&

.LONG TERM (Saturday through Thursday)...
Issued at 250 AM EST Fri Nov 22 2024

The large stacked low pressure system that brought yesterday`s
snowfall will depart eastward this weekend. Mid to upper-level
ridging induced by strong warm air advection over the Plains will
allow temperatures to rebound quickly by Sunday. However, the warm
up looks to be short-lived as a fast-moving trough arrives on
Monday. The pattern becomes a bit more complex thereafter as the
upper-level flow pattern trends more zonal. Energy over the west
coast then ejects eastward mid to late next week, potentially
leading to development east of the Rockies. Significant uncertainty
resides in this portion of the forecast period, however, and details
are murky regarding any resulting system.

Saturday through Monday

Low stratus persists through most of Saturday, clearing from
southwest to northeast by evening. This process could be slow,
perhaps a bit more than guidance suggests. Nudged temperatures
across our northeast downward a bit to compensate. Any lingering
snow cover should be completely melted by evening.

The aforementioned warm air advection will be in full force come
Sunday. Strong south-southwesterly flow in the lower-levels will
scour out lingering stratus. Ensembles are in generally good
agreement showing temperatures climbing into the mid to upper 50s by
Sunday afternoon. As low-level flow intensifies ahead of the
approaching shortwave, temperatures may not drop a whole lot Sunday
night into Monday morning. Lows may only be 5 to 10 degrees off the
previous afternoon`s high.

The trough arrives Monday, with only a weak surface low passing
north over the Great Lakes. Nevertheless, a potent cold front is
associated with the trough and should sweep through Indiana during
the afternoon hours on Monday. As such, high temperatures are
expected to occur early in the day before falling after fropa. Some
rain showers are possible along front as it passes through, but
given the fast-moving nature of the parent trough...amounts should
be light, generally under a quarter of an inch.

Tuesday through Friday

This period of the long range presents the greatest forecasting
challenge. Of particular interest is a potential system in the
Wednesday-Thursday timeframe. A few of the deterministic models have
occasionally shown a robust system passing south of Indiana such
that accumulation snow falls somewhere in the state. These solutions
seem to be outliers, as of now, with little support in the ensemble
suite. While accumulating snow is a possible outcome, it remains a
low-probability outcome at the moment. Nevertheless, with a
baroclinic zone emplaced by Monday`s trough over the central US,
progressive flow aloft, and energy situated along the western US...a
system of some kind developing and tracking eastward could be
favored. Details such as precipitation type, amount, location would
be determined by how this potential system develops and where it
tracks. We will keep precipitation chances under 50 percent for now,
and maintain a simple mention of "rain and snow" given the
uncertainty.

Days 8-14

Taking a peek at the very long range, model uncertainty remains high
but a few signals can be picked out from the noise. Namely, ridge-
building over the eastern Pacific showing up by late next week. A
highly amplified ridge edging into western Canada has the tendency
to dislodge cold air and shunt it southward. Such a pattern would
favor colder-than-average temperatures across much of the CONUS.

&&

.AVIATION (18Z TAF Issuance)...
Issued at 1101 AM EST Fri Nov 22 2024

Impacts:

- IFR ceilings will improve to MVFR by or very shortly after
  issuance time

- Winds 290-320 degrees with gusts to 20+ knots through 23z at
  KBMG and later at the other terminals

Discussion:

Would not rule out a lake-effect rain shower at KIND this afternoon,
otherwise confidence is good that IFR ceilings will improve to MVFR
by or shortly after 18z. The cyclonic flow and moisture trapped
below a strong inversion will keep skies cloudy until after 08z and
later when drying lower levels support a trend towards VFR.

Winds will be northwest and gusty through much of tonight and then
west and northwest Saturday less than 10 knots as surface high
pressure builds in.

&&

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

$$

UPDATE...MK
SHORT TERM...Puma
LONG TERM...Eckhoff
AVIATION...MK