Area Forecast Discussion Issued by NWS Indianapolis, IN
000
FXUS63 KIND 151334
AFDIND
Area Forecast Discussion
National Weather Service Indianapolis IN
934 AM EDT Fri Mar 15 2024
.KEY MESSAGES...
- Breezy during daytime Saturday through Monday
- Much colder early week with freezing temperatures Sunday night
- Hard freeze Monday night
&&
.FORECAST UPDATE...
Issued at 934 AM EDT Fri Mar 15 2024
- Mostly cloudy this morning, Decreasing cloudiness this afternoon;
Cooler.
Surface analysis late this morning shows strong high pressure in
place over the Central Plains. Low pressure was centered over
eastern NY with a surface with a cold front that stretches southwest
across southern PA to central KY and Western TN. Heavier
precipitation with this system was found mainly south of this front,
although KIND radar does show a thin band of showers of very light
precipitation across southern parts of Central Indiana drifting
southeast. GOES16 continues to show extensive cloudiness in place
across Central Indiana, with plenty of low cloud across the state
amid the ongoing cold air advection, while southern areas of the
state remained with the flow of convective debris higher clouds.
Water vapor imagery shows a merging of the northern upper flow and
southern upper flow across the Tennessee and Ohio river valleys.
Central Indiana was mainly impacted by the northern flow, providing
cooler and NW flow across our state.
This afternoon, the northwest flow aloft is expected to continue to
be predominate across Central Indiana. Forecast soundings show a
gradual drying through the course of the day, particularly by late
afternoon. However ongoing cold air advection is shown to continue
through the day and plenty of low clouds are found upstream. DESI
ensemble members suggest a gradual clearing from northwest to
southeast, mainly during the afternoon. Forecast soundings show a
gradual drying through the course of the afternoon and time heights
keep lower level moisture lingering through the afternoon. Thus will
keep skies cloudy through the morning hours and begin a clearing
trend by mid to late afternoon as subsidence and drying builds
across the forecast area.
&&
.SHORT TERM (Today and tonight)...
Issued at 140 AM EDT Fri Mar 15 2024
Low-amplitude shortwave passage has displaced warm conveyor belt
and associated deep moisture plume southeast of the area, and has
nudged modest cP air mass into Indiana. Noticeably cooler and
drier post-frontal air mass will occur today. There could be deep
enough mixing and momentum transfer for some gusts in the 15-20
mph range this afternoon and this would be more likely if the
stratus layer breaks early enough in the day. As of now, it
appears enough PBL moisture will be present to maintain a stratus
deck into at least mid-afternoon.
Our model blend starting point for temperatures has had a cool
bias that we`ve adjusted for the last few days, but with a shift
to a cold advection regime, it should perform reasonable well.
Near to slightly above normal temperatures are expected (mid-50s
for maximum temperatures).
Subsident end of upper jet and associated high MSLP should
enhance radiative conditions tonight and 1. with moist ground
lead to some patchy fog potentially, and 2. justify use of 25th
percentile blended guidance. The colder option is in line with
statistical and high-res guidance which handle these situations
better, typically.
&&
.LONG TERM (Saturday through Thursday)...
Issued at 140 AM EDT Fri Mar 15 2024
The synoptic-scale pattern this weekend will become much more
amplified with brief blocking in the west and high-latitude ridging
in western Canada helping to force deepening troughing over the
Great Lakes region. This is a configuration that should be
effective at dislodging Arctic air over central Canada and
bringing it southward in a modified state into our region. As a
consequence, by early next week we`ll likely be dealing with a
frost/freeze situation.
By mid week GEFS-weighted clusters are less amplified and lags
troughing some, and the Canadian ensemble-weighted cluster is
quicker and more amplified with ridging building in by the end of
the week. The sensible weather implications are a gradual warming
trend with greater chances of exceeding currently forecasted
temperatures than having to trend the forecast cooler. Throughout
this period, although there are some transient minor shortwave
perturbations and periods of ascent, increased cloud cover should
be the extent of the impacts. Meaningful moisture remains
confined to low latitudes until the very end of the week. Until
then, we don`t expect precipitation and chances, and only low
chances are anticipated by the end of the week.
Day 8-14: Ensemble clusters are largely out of phase with the
synoptic-scale trough/ridge pattern, and there is no discernible
signal for anomalous temperatures or precipitation at this time.
&&
.AVIATION (12Z TAF Issuance)...
Issued at 524 AM EDT Fri Mar 15 2024
Impacts:
- IFR ceilings trending MVFR and gradually improving later today
Discussion:
Northerly winds could gust as high as 15-18 knots during the warmest
part of the day today. Stratus should diminish by midday or early
afternoon, but IFR/MVFR ceilings will prevail until then. Ground
moisture and marginally favorable radiative conditions could lead to
patchy fog in some areas overnight, however the probability of
visibility reductions at TAF sites is low.
&&
.IND WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
UPDATE...Puma
SHORT TERM...BRB
LONG TERM...BRB
AVIATION...BRB