Bloomington, Indiana 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

747
FXUS63 KIND 231038
AFDIND

Area Forecast Discussion
National Weather Service Indianapolis IN
538 AM EST Sat Nov 23 2024

.KEY MESSAGES...

- Cloudy and cool morning before becoming Partly Cloudy this
  afternoon

- Warming trend this weekend

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

- Turning colder late in the coming week

&&

.SHORT TERM (Today and tonight)...
Issued at 252 AM EST Sat Nov 23 2024

Synopsis:

Surface analysis early this morning shows a large area of high
pressure in place throughout the Mississippi River Valley. This
large high was resulting in cool northwest flow across Central
Indiana. GOES16 shows continued cloudiness across Indiana and much
of the region. A clearing line from this low stratus was found
near the Mississippi river. The upper pattern aloft showed strong
and broad ridging in place over the Rockies, while a deep upper
low was found over New Jersey, influencing the pattern across the
East Coast. Indiana was between these two systems, with northwest
flow and subsidence in place aloft. Radar was quiet across the
region, however, the low clouds were resulting in some patchy
drizzle across the area.

Today -

Models today show the slow progression of ridging aloft over the
Rockies toward to the plains states. This will result in continued
northwest flow aloft along with subsidence through the day.
Meanwhile within the lower levels, the surface ridge axis near the
Mississippi Valley is expected to nudge eastward through the day,
reaching Indiana tonight. Warm air advection is show to arrive this
afternoon aloft. Forecast soundings and time heights keep the lower
level stratus across the area through the morning hours.  It is not
until the mid to late afternoon, when warm air advection and more
southwest lower level flow arrive, that time heights and forecast
soundings show a mixing out and drying of the lowest levels. Thus we
will expect a cloudy and cool morning, but some partial sunshine
by mid to late afternoon. Highs in the mid to upper 40s should be
reached this afternoon.

Tonight -

Subsidence will remain across Indiana tonight as the ridging over
the plains pushes toward the Mississippi River keeping weak lee side
flow in place across Central Indiana. The surface ridge axis
associated high pressure moving across the deep south will also push
across Indiana through the night. Forecast soundings and time
heights trend toward a dry column with subsidence and dry air
within the lower levels while continued warm air advection is seen
aloft. Thus will trend toward a mostly clear night, with lows in
the middle 30s.

&&

.LONG TERM (Sunday through Friday)...
Issued at 252 AM EST Sat Nov 23 2024

Two systems of interest are present in the long range. One,
arriving on Monday in the form of a cold front, looks to bring rain
to much of central Indiana. The second, arriving during the second
half of the coming week, may bring a mixture of precipitation types.

Sunday and Monday

Mid to upper-level ridging over the Great Plains builds into the
Midwest on Sunday. Increasing southwesterly flow ahead of an
approaching trough will allow temperatures to warm up into the
50s/60s. Continued warm air advection should prevent low
temperatures Sunday night from dropping too much. Lows may only be 5
to 10 degrees off the previous afternoon`s highs.

The aforementioned trough and its associated cold front arrive on
Monday. Cyclogenesis over the Great Lakes looks to occur late in the
day, which may be a little too late for significant precipitation in
Indiana. Nevertheless, models suggest light rain develop ahead and
along the cold front Monday morning and afternoon. Expect amounts no
greater than 0.25" on average. MSLP gradients tighten a bit, but not
enough for significantly gusty winds. Gusts up to 25mph are the most
probably outcome at the moment.

Tuesday and Wednesday

Much colder conditions are expected on Tuesday behind Monday`s cold
front. Strong cold air advection brings a quick shot of Cp air with
850mb temps of -5 to -10C. Despite a stiff northwesterly breeze,
surface temps likely drop well into the 20s by Tuesday morning,
especially north of the I-70 corridor. Highs Tuesday afternoon
recover only into the 30s / near 40. Low stratus may keep high
temperatures a bit lower than guidance suggests, especially across
our northeastern counties.

Wednesday should be quite similar to Tuesday. Modest warm air
advection associated with weak return flow should be offset by
increasing mid to high-level cloud cover. These clouds are a result
of increasing ascent ahead of a trough that is poised to eject into
the Plains. How the system evolves from there is shrouded in
uncertainty, as a variety of potential scenarios exist.

What can be said with most confidence is that there will be a storm
of some kind. A majority of guidance now shows the system in one
form or another, and its impacts to Indiana will depend on its track
and intensity. Our uncertainty stems from significant deviations
between various models, and even within in the same models run to
run, regarding the system`s track. Some of the deterministic
guidance (GFS) keep the system shunted far to the south without
Indiana seeing any precipitation at all. Others (ECMWF) show a more
robust system with Indiana firmly within the northern precipitation
shield. Despite the deterministic GFS being far to the south, its
ensembles still show a fair amount of members with a solution
similar to the ECMWF.

Another complicating factor is the trough itself may be loosely
organized as it emerges from the western states. Some guidance shows
it emerging in two pieces, which may or may not interact/merge.
Regardless, the trough looks to maintain a positive tilt on its
journey across the CONUS. Given a progressive zonal flow pattern
aloft, this should allow the system to move along quite quickly.

So what does this mean for Indiana? Given our position north of the
system and a relatively cold air mass in place...snow is a
possibility should the system track optimally. Until guidance comes
into greater consensus on the track, not much can be said about
potential amounts. Rain may complicate things further if the system
ends up too far north.

Thursday through Saturday

Regardless of how the mid-week system evolves, it should be exiting
the region by Friday (still some model differences in timing).
Decent model agreement exists with what happens afterward...namely,
much colder air dropping south as the system departs eastward.
Uncertainty exists with how cold of an air mass drops south of out
Canada, but it has potential to bring the coldest temperatures of
the season so far. Exactly how cold may also depend on potential
snow cover.

&&

.AVIATION (12Z TAF Issuance)...
Issued at 537 AM EST Sat Nov 23 2024

Impacts:

- IFR/MVFR ceilings through at least early afternoon.
- Light westerly flow today becoming southwest tonight.

Discussion:

Little overall change from the previous TAF issuance.

GOES16 continues to show extensive cloud cover across Central
Indiana and the region. Moisture within the lower levels looks to
remain trapped under an inversion over central Indiana at least
until early/mid afternoon. IFR and Low-MVFR ceilings to be the rule.

As warm air advection and southwesterly flow resumes by late
afternoon. This heating and mixing should bring about and end to the
MVFR/IFR Cigs. However confidence remains low for this. Forecast
soundings and Time heights at that time show a loss of saturation
within the lower levels.

Uncertainty remains. If not enough mixing occurs, lower level cloud
decks may be slow to clear this evening and overnight.

&&

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

$$

SHORT TERM...Puma
LONG TERM...Eckhoff
AVIATION...Puma