IND issues Area Forecast Discussion (AFD) at Nov 13, 8:26 AM EST497
FXUS63 KIND 131326 AAA
AFDIND
Area Forecast Discussion...UPDATED
National Weather Service Indianapolis IN
826 AM EST Wed Nov 13 2024
.KEY MESSAGES...
- Rain arrives late in the day and continues into Thursday, possibly
heavy at times.
- More rain chances next week
- Above normal temperatures expected through early next week
&&
.FORECAST UPDATE...
Issued at 826 AM EST Wed Nov 13 2024
Classic baroclinic leaf is seen in satellite imagery upstream this
morning, indicative of an approaching trough and its associated
forcing for ascent. This will lead to rain later today and tonight.
The previous forecast has this covered well with probabilities at
certainty levels. Opportunities to add more precesion will primarily
be with onset timing, potentially breezy conditions this eveing, and
rain departure timing. We will refine this today but expect only
minor changes at most.
It appears by around mid-afternoon ascent and moistening of the
lower troposphere will be enough for rain to start. The contiguous
area of rain should last until the pre-dawn hours, after which low-
level saturation and convergence beneath the dry conveyor belt may
lead to lingering light showers and/or drizzle into early Thursday.
&&
.SHORT TERM (Today and tonight)...
Issued at 300 AM EST Wed Nov 13 2024
Current satellite imagery shows extensive high clouds stretching
from the Ohio Valley to the southern Plains. These clouds are
associated with moisture streaming in ahead of an upper trough which
is going to provide another round of beneficial rainfall to the
area. Temperatures overnight have struggled to cool much, currently
range from the upper 30s to low 40s. The reason for this is a
tightening pressure gradient between a strong surface high over
Quebec and a deepening low across the central Plains has kept winds
elevated.
Quiet weather conditions should persist through midday, but the
upper trough and attendant surface low moving through late in the
day will promote widespread precipitation. Increasing large scale
ascent combined with warm-moist advection quickly moistening what
is currently a very dry column, should allow for precipitation to
start overspreading the area by mid-late afternoon. Precipitation
will then continue through tonight as the system gradually
progresses across the region. Most guidance suggest a dry slot
moves in late tonight leading to slightly lower coverage of
showers. In addition, the strongest forcing begins to shift
eastward by this time. POPs were gradually lowered after 1am for
these reasons.
Beneficial rainfall amounts around 0.5 to 1.0 inches are possible in
most locations, thanks in part to deeper moisture from the remnants
of Hurricane Rafael lifting northward. Southwest portions of central
Indiana could see over an inch where guidance shows deeper moisture.
An increasingly drier airmass further north and east will tend to
limit overall QPF some. Expect above normal temperatures through the
short term. The diurnal temperature swing from today into tonight
will be rather small due to widespread cloud cover and
precipitation.
&&
.LONG TERM (Thursday through Tuesday)...
Issued at 300 AM EST Wed Nov 13 2024
An upper low will move across central Indiana on Thursday. The area
will also be under the influence of the left exit region of an upper
jet. Although the deeper moisture will have moved east of the
forecast area by 12Z Thursday, enough moisture should still linger
for the forcing to work with to produce scattered to numerous
showers, with highest coverage east where better moisture will
linger.
Will go likely category PoPs for the eastern half or so of the area
Thursday morning, with chance PoPs west. PoPs will diminish during
the afternoon as the system moves east. Will have to watch out for a
couple of things though. A TROWAL may bring another area of rain to
the northeast Thursday afternoon if it develops, and drizzle may
linger behind the showers.
Will keep some low PoPs Thursday evening across the northeast to
account for the potential TROWAL. Drizzle may linger as well, but
at the moment am not confident enough to put it in the forecast. Low
clouds most likely will linger through the night, which should
prevent widespread fog.
An upper ridge will move in for Friday into Saturday. Low clouds may
linger longer on Friday than models indicate (which is typical for
November), but more sunshine will be around for Saturday.
Uncertainty then ramps up for the remainder of the long term period,
as questions remain on how fast a large upper low will develop and
then move east into the area. Using the DESI viewer shows
clustering among long range ensembles show a split among a few
different solutions.
For now, will not deviate much from blended guidance, which keeps
chances for rain in the forecast from Sunday night into Wednesday.
Temperatures will be above normal for much of the long term, with a
potential for cooler temperatures on Wednesday depending on the
speed of the upper system.
Looking beyond Wednesday, if the upper trough settles across the
area later next week, below normal temperatures will occur along
with chances for precipitation.
&&
.AVIATION (12Z TAF Issuance)...
Issued at 633 AM EST Wed Nov 13 2024
Impacts:
- Rain arrives by mid-late afternoon today
- Ceilings to rapidly deteriorate to IFR and visibilities to
MVFR or worse during the late afternoon or evening
- Wind gusts to around 18-20 kts late afternoon with higher gusts
possible into the evening
Discussion:
High pressure will keep conditions quiet through midday today. Winds
will become more southeasterly after daybreak as high pressure
shifts east.
A gradual increase in mid and high clouds is expected before rain
pushes into the area late in the day. Wind gusts around 18-20KT out
of the southeast are possible in the afternoon. There is potential
for stronger gusts as heavier rain moves in during the evening.
Ceilings will rapidly deteriorate to IFR within a few hours of rain
onset as the rain becomes more widespread and a bit heavier.
Visibilities will also likely become MVFR with a few periods of IFR
possible in the heaviest showers. LIFR conditions cannot be ruled
out either.
Depending upon persistence of gusts, there may be potential for
modest low level wind shear tonight, but this remains uncertain.
&&
.IND WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
UPDATE...BRB
SHORT TERM...Melo
LONG TERM...50
AVIATION...Melo
Source:
IND issues Area Forecast Discussion (AFD) at Nov 13, 8:26 AM EST---------------
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