IND issues Area Forecast Discussion (AFD) at Oct 16, 6:17 PM EDT860
FXUS63 KIND 162217
AFDIND
Area Forecast Discussion
National Weather Service Indianapolis IN
617 PM EDT Wed Oct 16 2024
.KEY MESSAGES...
- Tonight: Widespread freezing temperatures and frost expected.
- A Freeze Warning is in effect tonight from 06z-13z.
- Additional frost likely Thursday night, trending warmer
afterwards.
&&
.SHORT TERM (This evening through Thursday)...
Issued at 239 PM EDT Wed Oct 16 2024
Cold air advection continues this afternoon from the north-
northwest. Long fetch over the still-warm Lake Michigan has allowed
for efficient lake-effect cloud cover today. The north-south
oriented band of clouds essentially runs the entire length of
Indiana. Some changes visible on satellite include a transition from
a smooth stratus to a convective stratocumulus appearance. This can
be attributed to boundary layer mixing amid a still efficient mid-
October sun. As we lose daytime heating this evening, lingering
stratocumulus is expected to rapidly diminish. A few pockets of
denser cloud cover could remain across our east into the late
evening hours, however.
With the core of a surface high pressure system moving in to the
region this evening, conditions favor excellent radiational cooling
potential. Diminishing clouds and calm to light winds will lead to a
rapid drop-off in temperatures in the 1 to 2 hour period following
sunset. As of this afternoon, 850mb temperatures are below freezing,
residing in the 0 to -4C range. Warm air advection aloft from the
northwest, interestingly enough, should allow these values to climb
into the 0 to 5C range. Despite this modest warm up in the mid-
levels, a cold night is anticipated given the aforementioned
radiative cooling potential.
A Freeze Warning has been issued for the entire CWA tonight, mainly
for temperatures in the 30 to 32 degree range. A few pockets of
upper 20s are possible in the typical rural cold spots, but these
shouldn't be widespread. On the contrary, some of our urban areas
may remain above freezing through the night. Nevertheless, most of
the area should see near to below-freezing temperatures and thus
feel that a Freeze Warning is justified. Frost will be widespread as
well. There is a low chance of patchy fog across portions of our
north and eastern counties, especially near warm bodies of water and
rivers.
Freezing temperatures, frost, and any fog quickly diminish after
sunrise. A rather large diurnal swing in temperatures is likely
tomorrow as mid-level warm air advection continues. Full sun and a
light south breeze should promote high temperatures into the lower
and middle 60s. A very dry column and continued subsidence will
inhibit diurnal cumulus growth during the afternoon hours.
&&
.LONG TERM (Thursday night through Wednesday)...
Issued at 239 PM EDT Wed Oct 16 2024
Thursday Night Through Monday.
Dry and quiet weather is expected going into the weekend as a broad
upper level ridge gradually moves into the Ohio Valley which will
continue the trend of warming temperatures along with mostly clear
to clear skies. Areas of frost are likely to return Thursday night
as skies clear out again, but with slightly warmer conditions
expected the impacts will be less than for what is expected tonight.
A Frost Advisory may end up being needed depending on how what the
dew point recovery looks like tomorrow as with clear skies and calm
winds, radiational cooling will be maximized. Will address these
concerns tomorrow after the expiration of the ongoing Freeze Warning.
Surface flow will be southerly beginning Friday morning, but air will
generally be advecting from eastern Kentucky with no connection to
the Gulf of Mexico which will keep surface dew points in the 30s.
This will combine with temperatures in the low to mid 70s Saturday
and Sunday to bring slightly elevated fire weather danger as RH
values drop to around 30 percent. Winds will be less than 10kts
which will limit the fire danger, but with many areas not having
seen more than a couple tenths of an inch this month, fuels will be
dry. The ridge will gradually begin to break down Sunday into Monday
with continued dry and seasonably warm conditions ahead of the next
upper level wave.
Tuesday and Wednesday.
Models continue to trend downwards on the rain threat associated
with a weak upper level low as it tracks from western Kansas into
the lower Great Lakes region. Moisture out ahead of the low will be
marginal at best with a lot of dry air below the moisture layer
which will likely lead to a gradual dissipation of showers Tuesday
into Tuesday night as the low tracks to the northeast. There is a
low chance for some rain, but the higher end ensemble outcomes show
only a tenth of an inch of rain or so with even the 75th percentile
near zero. Thus will keep the low chance POPs with the highest
potential Tuesday evening into the early overnight. Looking later in
the week, the pattern will trend more active while remaining near
normal on temperatures.
&&
.AVIATION (00Z TAF Issuance)...
Issued at 618 PM EDT Wed Oct 16 2024
Impacts:
- None
Discussion:
Stratocu are finally departing early this evening as high pressure
expands into the Ohio Valley. Expect light and variable winds
overnight with clear skies. Deeper subsidence will advect into the
region for Thursday maintaining clear skies. Light southerly flow
will develop at around 5kts.
&&
.IND WATCHES/WARNINGS/ADVISORIES...
Freeze Warning from 2 AM to 9 AM EDT Thursday for INZ021-028>031-
035>049-051>057-060>065-067>072.
&&
$$
SHORT TERM...Eckhoff
LONG TERM...White
AVIATION...Ryan
Source:
IND issues Area Forecast Discussion (AFD) at Oct 16, 6:17 PM EDT---------------
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