IND issues Area Forecast Discussion (AFD) at Feb 9, 10:57 PM EST923
FXUS63 KIND 100357
AFDIND
Area Forecast Discussion
National Weather Service Indianapolis IN
1057 PM EST Sun Feb 9 2025
.KEY MESSAGES...
- Active weather pattern with chances for wintry precipitation:
Tuesday, Wednesday night into Thursday, and next weekend.
- Snow possible on Tuesday across southern portions of central
Indiana with minor accumulations.
- More impactful system expected midweek with the potential for
multiple precipitation types, exact details remain uncertain.
&&
.FORECAST UPDATE...
Issued at 1004 PM EST Sun Feb 9 2025
Clouds are slowly clearing across the northwestern forecast area
this evening, but remain plentiful elsewhere. Adjusted sky cover to
reflect current conditions. Lower clouds should continue to erode,
but some mid and high clouds look to linger based on upstream
conditions.
Will allow skies to become at least partly cloudy all areas given
the above trends.
Low temperatures might be a little cool south if clouds do not break
up as much as expected, but left them alone for now and will
continue to monitor.
&&
.SHORT TERM (This evening through Monday)...
Issued at 301 PM EST Sun Feb 9 2025
Lower stratus has fully filled back in and encompassed central
Indiana since late morning. Under light northwest winds...19Z
temperatures were primarily in the low to mid 30s as the cloud deck
had stunted warming.
A broad area of high pressure will drift across the region through
late Monday with dry weather expected for the forecast area. Cloud
coverage will initially be a focus but clearing will take place
tonight and Monday morning as deeper subsidence advects into the
region. Monday will be an overall pleasant day prior to the much
more unsettled regime that develops by Tuesday and continues for
much of the next week.
The stratus is the result of moisture remaining trapped beneath an
inversion within the boundary layer. The inversion will give way
slowly this evening into the overnight as drier air filters down
into the lower levels...with lower clouds finally mixing out and
being replaced by thin mid and high level clouds moving through the
Ohio Valley. These higher clouds will persist on Monday for much of
the day with clouds thickening and beginning to lower by early
evening ahead of the next storm system developing and set to impact
the Ohio Valley by early Tuesday. More on this system in the Long
Term section below.
Temps...clearing skies and light winds overnight will enable
temperatures to drop into the teens over northern counties with
lower and mid 20s further south. Low level thermals support highs
ranging from the mid 30s north to the lower 40s south.
&&
.LONG TERM (Monday night through Sunday)...
Issued at 301 PM EST Sun Feb 9 2025
A transition to a more active pattern is expected later this week as
the baroclinic zone lifts back north with a more progressive and
amplified pattern developing aloft. The baroclinic zone setting up
near the region could lead to a sharp gradient in temperatures at
times which suggest opportunities for multiple precipitation types.
Monday night through Tuesday night...
The first system approaches central Indiana early in the period.
Latest guidance continues to show the disturbance moving south of
the Ohio River. While overall forcing and anomalous moisture favor
widespread precipitation near or south of the Ohio River, questions
remain on how far north the precipitation makes it. A sharp gradient
in QPF is likely from Kentucky/Tennessee to central Indiana due to
lingering low-level dry air towards the north. Thermal profiles will
be cold enough to support all snow for any areas that do see
precipitation. The best chance for snow is across the south with
minor accumulations possible on grassy or elevated surfaces.
Look for precipitation to taper off around Tuesday evening once the
aforementioned system shifts east followed by high pressure building
in. Increasing large scale-subsidence will briefly promote quiet
weather conditions Tuesday night into Wednesday morning before
another system moves in.
Wednesday through Friday...
A more impactful system looks likely late Wednesday as a stronger
low pressure system approaches the region. Exact details on the
track of this system or overall impacts continue to remain uncertain
due to a large spread in model solutions. Both ECMWF and GFS
ensemble surface low tracks range from portions of central IN to the
Deep South. In addition, forecast soundings show a developing warm
nose aloft from warm air advection which will lead to the potential
for a wintry mess of multiple precipitation types. At this time, it
appears areas N/W of Indianapolis have the best chance to remain all
snow and receive accumulating snow. Locations further south and east
could see little to no snowfall accumulation with sleet, freezing
rain, or even all rain mixing in. Uncertainty remains rather high on
how this event unfolds, but these details will become clearer in the
coming days once model guidance becomes better aligned.
Surface high pressure returns Thursday and Friday providing quiet
weather conditions. Cold air advection will likely support below
normal temperatures to end the work week. Overnight temperature are
going to be particularly cold Thursday night into Friday morning
with lows ranging from the single digits to teens.
Friday night onward...
Don't be fooled by the mundane weather Thursday/Friday as another
system sets its eye on central Indiana. Long range guidance shows
another potentially impactful winter system tracking near the region
next weekend. However, there is even larger spread in model
solutions as expected which leads to lower confidence. Impacts will
greatly depend on where the developing surface low tracks. There are
a few details that are becoming evident in the ensembles though. The
first being that very anomalous moisture will surge northward over
the eastern CONUS within a strong-broad LLJ. This combined with
increasing dynamics should favor heavy precipitation somewhere near
the deep south or Ohio Valley.
The uncertainty lies in how far north the rich gulf moisture surges.
Temperatures will be cold enough at times to support wintry
precipitation, but with the baroclinic zone nearby there is the
potential for multiple precipitation types. The second detail
becoming clearer is that a cold airmass will likely settle in behind
the system with below normal temperatures (possibly well below
normal at times) for much of the following week. The CPC 8-14 day
outlook supports this showing below normal temperatures across the
region.
&&
.AVIATION (06Z TAF Issuance)...
Issued at 1057 PM EST Sun Feb 9 2025
Impacts:
- Would not rule out brief MVFR ceilings through 09z and or
very shallow ground fog through 13z
Discussion:
Patches of stratocu remain across the area per GOES-16 RGB
Nighttime Microphysics and obs. So, will leave in a scattered
strato cu deck around 2500 feet in through 09z. Hi-Res soundings
suggest subsidence and drier air gradually filtering in will
result in the cu dissipating toward daybreak. Otherwise, plenty of
upstream mid clouds will move in in the southwest flow aloft. Hi-
res soundings and low dew point depressions also hint at possible
for shallow ground fog into the morning.
Winds will be very light northwest or calm tonight and then
becoming north and northeast later today and tonight.
&&
.IND WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
UPDATE...50
SHORT TERM...Ryan
LONG TERM...Melo
AVIATION...MK
Source:
IND issues Area Forecast Discussion (AFD) at Feb 9, 10:57 PM EST---------------
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