IND issues Area Forecast Discussion (AFD) at Feb 21, 12:25 PM EST165
FXUS63 KIND 211725
AFDIND
Area Forecast Discussion
National Weather Service Indianapolis IN
1225 PM EST Fri Feb 21 2025
.KEY MESSAGES...
- Very light flurries possible at times through daybreak across
the northeastern half of central Indiana
- A gradual warming trend through the weekend into early next week,
with highs back in the upper 40s to mid 50s for the early portion
of the work week
- Breezy at times early next week
- A low chance for rain Monday night with more substantial chances
mid week
&&
.FORECAST UPDATE...
Issued at 943 AM EST Fri Feb 21 2025
Another cold, winter day expected for Central Indiana before a
weekend warm up. For this morning's update, focusing on the slowly
retreating area of low stratus clouds across East Central Indiana.
Latest satellite imagery shows the cloud deck along and east of the
I-69 corridor. IND ACARs soundings shows this cloud deck stuck under
a strong low level inversion less than 1 km agl, making it difficult
for low level moisture to lift. Expect this cloud deck to slowly
push eastward over the next few hours, with all locations within
Central Indiana under mainly sunny skies by the 12pm-1pm timeframe.
Along and west of the I-69 corridor, sunny skies should allow for
sufficient surface heating with highs moderating some compared to
the past few days as all locations reach the mid to upper 20s. If
clouds stick around longer for far eastern Indiana, those areas
could be stuck in the lower 20s. Despite highs still below freezing,
the increasing late February sun angle should aid in further snow
melt across the region.
&&
.SHORT TERM (Today and tonight)...
Issued at 317 AM EST Fri Feb 21 2025
A partially lake-enhanced stratus deck across the northeastern half
or so of central Indiana this morning is likely to enhance the
minimum temperature gradient this morning, keeping mins up a few
degrees under the cloud.
The more interesting element is that temperatures within the cloud
deck have been within the range of efficient ice nucleation, and
this, along with some very weak remnant forcing for ascent as the
tail end of the prior upper trough exits the area has been just
enough to squeeze out some very light flurries underneath the cloud
deck. On visual observation, they are difficult even to see, but
they are there, and being reported by observers at IND and a couple
of other sites to the east in Ohio staffed by overnight observers.
It is an incredibly shallow stratus deck, only about 1-3kft in
thickness per 88D VAD profiles, based just above 2kft AGL, so the
radar is either under or overshooting what few echoes there might
be, with the exception of some slight enhancement moving south out
of the city - this may be the result of industrial enhancement from
steam stacks on the near southside.
Nevertheless - these flurries may continue off and on through the
remainder of the night as the stratus deck slowly begins to shift
eastward with flow backing more westerly with time, but they are
highly unlikely to be of significant impact. Will carry a mention
through daybreak.
Once the stratus deck erodes/shifts eastward, mostly clear skies are
expected throughout the day with relatively light winds becoming
more westerly and then southwesterly and southerly with time through
the day and into tonight as the surface high pushes eastward across
the area. Some mid and high cloud will likely overspread the area
tonight ahead of an upper wave that will pass to our south, but
very dry low levels will prevent any measurable precipitation,
with even flurries difficult to come by given the magnitude of
dryness below 10kft.
Temperatures this morning will likely sink well into the single
digits where skies remain clear, but be held in the low to mid teens
under the cloud deck. Plentiful sunshine and weak warm advection
late in the day should bring highs this afternoon up into the upper
20s and perhaps the low 30s in a couple of spots, with another cold
night tonight but not quite so cold due to the aforementioned high
cloud and a slight increase in dewpoints - lows tonight look to drop
into the high single digits to mid teens across the area.
&&
.LONG TERM (Saturday through Thursday)...
Issued at 317 AM EST Fri Feb 21 2025
The long term period looks to be largely dry, but substantially
warmer than in recent days, at least late in the weekend through mid
week, when multiple days in the 40s to mid 50s appear likely,
despite continued northwest flow aloft or quasizonal flow at best.
Multiple weak upper level waves in the aforementioned northwest flow
aloft between the subtropical ridge near Baja California and the
polar vortex pivoting over Hudson Bay will move near the area
through the long term, though none of them are particularly
substantial or close enough to have an impact until later in the
period - one Monday night into Tuesday and another more significant
wave Wednesday into Thursday.
Despite the continuation of northwest flow, low to mid level warm
advection ahead of these waves and the erosion of low level Arctic
airmass associated with the weakening and retreating surface high
influencing the early portion of the forecast will bring
temperatures up substantially, with highs back into the 40s and
potentially 50s late in the weekend and into mid week next week.
Thus, precipitation associated with these disturbances is likely to
be primarily rain, and substantial amounts appear unlikely at this
time with no significant Gulf moisture available.
There is some signal late in the seven day period and into early
March for another Arctic intrusion into the region, but uncertainty
is high given substantial model differences.
Multiple breezy afternoons are likely early to mid next week as a
deepening PBL taps into moderate flow aloft and promotes gustiness.
Gusts at or above 25-30 MPH will be possible at times, particularly
Monday into Thursday.
&&
.AVIATION (18Z TAF Issuance)...
Issued at 1225 PM EST Fri Feb 21 2025
Impacts:
- None
Discussion:
High pressure will be the dominant weather influence across Indiana
over the next 24 hours with mainly VCM expected.
Surface high pressure slides over the region tonight before shifting
eastward tomorrow. Subsidence under the high and dry air will lead
to mainly clear skies other than a few high clouds passing by during
the morning hours tomorrow. Southwest winds will remain under 10 kts
this afternoon at all TAF sites then drop to near calm during the
overnight hours. A tightening pressure gradient tomorrow afternoon
in addition to boundary layer mixing may result in sustained winds
08-13 kts with gusts to 18 kts at times. No cig or vis issues
expected during the period.
&&
.IND WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
UPDATE...CM
SHORT TERM...Nield
LONG TERM...Nield
AVIATION...CM
Source:
IND issues Area Forecast Discussion (AFD) at Feb 21, 12:25 PM EST---------------
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