IND issues Area Forecast Discussion (AFD) at Nov 14, 5:35 PM EST974
FXUS63 KIND 142235
AFDIND
Area Forecast Discussion
National Weather Service Indianapolis IN
535 PM EST Thu Nov 14 2024
.KEY MESSAGES...
- Isolated to scattered brief showers and or drizzle through the
evening.
- Cloudy through early Saturday then partial clearing.
- Rain chances return Tuesday followed by a trend toward cooler
temperatures by the end of the week.
&&
.SHORT TERM (This evening through Friday)...
Issued at 220 PM EST Thu Nov 14 2024
In the wake of departing trough, advection is generally neutral. Low-
level moisture is still present as is evident in satellite imagery
with broad area of low stratus. Lower tropospheric moisture depth
and steepening low-level lapse rates may be enough for shallow
convective showers into the evening. These often have small drops
and are more like drizzle, though they can be heavier and more
intermittent. Coverage/intensity should decrease this evening, but
stratus will persist through tomorrow. We have lowered temperatures
slightly tomorrow as we expect similar condition to today with
persistent stratus limiting surface heating.
&&
.LONG TERM (Friday night through Thursday)...
Issued at 220 PM EST Thu Nov 14 2024
Fog initially seemed at least possible Friday night into Saturday
morning, but stratus looks to persist into this period. Low level
moisture trapped beneath a strong subsidence inversion this time of
year often results in prolonged stratus. On the western edge of the
stratus, fog is more likely, but this now appears to be in Illinois
or Missouri. With PBL moisture becoming less and mixing on Saturday,
stratus is likely to break around midday. By then, mid-high clouds
from the upstream system and Pacific moisture plume, in addition to
increasingly MSLP gradient should limit potential fog Sunday
morning.
We will be on the windward side of prograding mean ridge axis
Sunday, so temperatures will be about 10 degrees above mid-November
climo. We still have low probabilities of rain for portions of the
area Sunday night into early Monday, but trends in almost all of the
ensemble models have been for less coverage and further north. This
is tied to a trend toward a less amplified northern stream shortwave
trough. There is still modest moisture return indicated in the
models and ascent with a midlevel thermal gradient, so will leave
slight chance in.
Still warm Monday and Tuesday as ridging resurges preceding the next
system. There is limited ensemble spread on lead shortwave trough
passing to our northwest Tuesday. Its associated warm conveyer
belt/moisture surge should bring a band of rain Monday night and
early Tuesday, but cold advection will be minimal as this trough
weakens and moves east at the same time digging trough evolves over
the Plains.
Wednesday onward we will enter a period of low-mid range
precipitation probabilities and colder temperatures. The synoptic-
scale pattern is still somewhat uncertain as EPS-weighted clusters
hold the Plains trough west longer, while GFS is deeper and more
progressive. This may primarily impact temperatures Wednesday as the
former camp offers an opportunity to warm prior to the onset of
stronger cold advection, compared to the latter camp. Details with
regards to periods of enhanced forcing/ascent with rotating
vorticity maxima are unclear. Also, cold advection magnitude appears
to be modulated by substantial high-latitude ridging in this
blocking pattern, so whether or not temperatures are cold enough for
snow late next week is not totally clear. Temperatures will be
marginal. Steep lapse rates beneath the cold core low would support
a more showery regime.
Day 8-14 will start off with troughing, and there appears to be some
signal for this to persist. Near to below normal temperatures
and near normal precipitation would result.
&&
.AVIATION (00Z TAF Issuance)...
Issued at 534 PM EST Thu Nov 14 2024
Impacts:
- MVFR/IFR ceilings may improve after 21z Friday, mainly at KLAF and
KHUF
- Some visibility reduction due to mist/drizzle possible through
04z
Discussion:
MVFR and IFR ceilings will mostly continue through the TAF period as
Hi-Res soundings are revealing plenty of trapped low level moisture.
Also, brief MVFR and worse visibilities are also possible in fog
through late this evening. Some improvement in ceilings is possible
Friday afternoon as upper ridging moves overhead and Hi-Res
soundings show drying.
Winds will be WNW near 10 knots this evening but become light from
the northwest overnight and Friday.
&&
.IND WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
SHORT TERM...BRB
LONG TERM...BRB
AVIATION...MK
Source:
IND issues Area Forecast Discussion (AFD) at Nov 14, 5:35 PM EST---------------
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