IND issues Area Forecast Discussion (AFD) at Feb 17, 11:59 PM EST
753
FXUS63 KIND 180459
AFDIND
Area Forecast Discussion
National Weather Service Indianapolis IN
1159 PM EST Mon Feb 17 2025
.KEY MESSAGES...
- Cold Weather Advisory through 9AM with wind chills below -10.
- Accumulating snow is expected Tuesday night. The highest amounts
of an inch or two will be south of Bloomington.
- Temperatures will remain brutally cold through the week with
moderating temperatures starting this weekend.
&&
.FORECAST UPDATE...
Issued at 904 PM EST Mon Feb 17 2025
- Cloudy, very cold, with flurries possible Overnight.
Surface analysis late this evening shows a ridge or arctic high
pressure stretching from the northern plains, across IA to southern
Indiana and eastern KY. Cold, arctic air has settled across Central
Indiana with temperatures in the teens and dew points in the single
digits. A moderate pressure gradient remains across Central Indiana.
This was allowing for wind chill values from -2 to around 10 across
the forecast area. Water vapor across the area shows nearly zonal
flow across Central Indiana however this zonal flow was a part of a
very broad and elongated cyclonic circulation centered near the Gulf
of St. Lawrence that stretched westward across the Canadian
provinces to Alberta. Water vapor showed a stream of Pacific
moisture streaming across Baja California to Kansas and MO. Some of
that was resulting in snow showers or flurries across
Kansas/Missouri and even eastern IL.
Overnight, models continue to suggest the moderate pressure gradient
across the area will remain in place, allowing for winds around 10
mph while cold air advection continues. HRRR fails to pick up on the
ongoing flurries or suggest their progress across the area. At the
moment, it appears too dry within the lower levels as forecast
soundings through the night do not suggest saturation there at any
point. Thus feel the bulk of any precipitation will remain as
flurries or virga. Ceilings across the area are failing to be
present below 4-5,000 feet and in many cases are 8,000 to 12,000
feet, indicative of dry air. Thus will limit any precipitation
chances overnight, but keep the flurry mention.
Given the cloud cover and expected winds, models show wind chill
values near -10 across the Kokomo and Lafayette areas, with single
digits at most other locations. Given this ongoing Cold Weather
advisory seems on the mark, with single digit lows at most spots.
&&
.SHORT TERM (This evening through Tuesday)...
Issued at 235 PM EST Mon Feb 17 2025
A baroclinic zone set up to the southwest of the area along with
cold surface high pressure will be the influences in
the weather across central Indiana during the short term.
Clouds will continue to increase across central Indiana for the
remainder of the afternoon as moisture aligns with the baroclinic
zone. Isentropic forcing to the west along this zone will generate
some light snow across Illinois, but this should have a hard time
making it into central Indiana as it moves away from forcing and
encounters very dry low levels.
Will add some flurries to portions of the western forecast area
later this afternoon as some flakes may survive the dry low levels.
Similar conditions will persist tonight into early Tuesday, but
some isentropic forcing will be close to or even in the southwestern
portions of the area. Short term models are more bullish with snow
coverage, dropping a few tenths of snow across the southern forecast
area. Other models have little if any accumulating snow.
With the surface high still bringing in very dry low level air, the
snow will still have to fight to reach the ground. Will keep PoPs
low for now and confined to the southwest third or so of the area
(with flurries extending farther northeast from there). Will leave
out any accumulation for now.
Will have to watch though, because if more of the snow reaches the
ground, given it's fluffy nature in the cold airmass, accumulations
up to around a half inch could occur quickly (which could have an
impact on morning drivers in the southwest).
The baroclinic zone will get pushed southwest some for the
remainder of Tuesday, and the cold high pressure will remain
dominant at the surface. Will keep some low PoPs going in the
southwest. Skies will be partly to mostly cloudy.
Looking at temperatures, even with clouds around readings will still
fall back into the low single digits above zero north to around 10
far south. With the center of the surface high well north, winds
will still be up, pushing wind chills to near Cold Advisory numbers
(-10). However, for now, looks like if those numbers are reached it
won't be for long enough for an Advisory to be issued. Will continue
with a SPS for cold.
With the cold start and plentiful clouds around, highs on Tuesday
will be in the teens most areas.
&&
.LONG TERM (Tuesday night through Monday)...
Issued at 235 PM EST Mon Feb 17 2025
Tuesday Night through Wednesday...
An upper low will close off over the upper Midwest Tuesday night as
a lead short wave is ejected around the base of the low and into the
Ohio Valley. This synoptic forcing along with a 140 knot upper jet
nearby and deep moisture through a deep dendritic growth zone per Hi-
Res soundings will support at least some light snow accumulation and
mainly over areas well south of I-70. Snow ratios of 16-20:1 could
result in higher than anticipated amounts for now will roll with
near WPC amounts of an inch or two south of Bloomington and much
lesser amounts further north.
The system will move to the east on Wednesday which should any
accumulating snow. Meanwhile, cold advection around a 1050 millibar
Arctic high over the Dakotas will continue to filter in the brutally
cold temperatures with overnight lows mostly in the single digits
and wind chills as cold as a degree or two below zero over northern
sections.
Wednesday Night through Monday...
The cold advection will continue through late week as the Arctic
high plunges south into the Middle Mississippi Valley on Friday. The
coldest temperatures and lowest wind chills look to be Wednesday
night with lows in the single digits and wind chills to 10 or more
degrees below zero over the Upper Wabash Valley, where some clearing
is possible per model soundings. Could see a few snow showers or
flurries Wednesday night as the Upper Midwest closed low moves
through but with moisture lacking, only expect another dusting or so.
The weekend will see moderating temperatures as the high moves to
the south. Temperatures will likely return to above normal in the
upper 30s to lower 40s by Sunday and even warmer next Monday.
&&
.AVIATION (06Z TAF Issuance)...
Issued at 1158 PM EST Mon Feb 17 2025
Impacts:
- Brief MVFR vsbys/cigs 08Z to 13Z with light snow
Discussion:
Generally VFR conditions expected through the TAF period with brief
periods of light snow early this morning. Highest confidence in snow
will be at BMG and HUF with low chances at IND and near zero at LAF.
Cigs may briefly drop into MVFR but looking upstream, chances are
low. Otherwise cloudy to mostly cloudy skies expected through the
rest of the TAF period with cigs around 050 and winds northerly at 6-
10kts.
&&
.IND WATCHES/WARNINGS/ADVISORIES...
Cold Weather Advisory until 9 AM EST Tuesday for INZ021-028>031-
035>041-043>046.
&&
$$
UPDATE...Puma
SHORT TERM...50
LONG TERM...MK
AVIATION...White
Source: IND issues Area Forecast Discussion (AFD) at Feb 17, 11:59 PM EST (https://mesonet.agron.iastate.edu/p.php?pid=202502180459-KIND-FXUS63-AFDIND)
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