IND issues Area Forecast Discussion (AFD) at Jul 10, 12:31 AM EDT249
FXUS63 KIND 100431
AFDIND
Area Forecast Discussion
National Weather Service Indianapolis IN
1231 AM EDT Wed Jul 10 2024
.KEY MESSAGES...
- Windy on Wednesday; Beryl remnants exiting.
- Shower and Thunderstorms chances Thursday through Monday.
- Highs in the upper 80s and lower 90s Thursday-Monday.
&&
.FORECAST UPDATE...
1016 PM EDT Tue Jul 9 2024
The surface remnants of Beryl were across the southwestern forecast
area this evening. A warm front extended from the low northeast to
near Shelbyville. The dry slot of the system had worked ahead of the
surface low along and west of a Terre Haute to Bedford line.
Satellite images show cloud tops warming across central Indiana, and
convection has been on a general downward trend this evening as
well. Mesoanalysis still shows some decent effective shear and 0-3km
CAPE east of the dry slot, but convection is having a hard time
tapping into that energy.
Will still have to keep an eye on the convection as it moves east as
850mb winds are still expected to increase some before the line
exits. However, with diurnally weakening CAPE and storms already
having trouble using the available energy, feel that odds of severe
weather will continue to lower this evening.
With plentiful moisture remaining in place, locally heavy rain will
remain a threat, especially north of the surface low track.
Adjusted PoPs and temperatures as needed to reflect current trends.
Low temperatures look good, so made no changes there. Winds will
increase in speed late tonight in the far west and the current
forecast reflects this week.
&&
.SHORT TERM (This evening through Wednesday)...
Issued at 306 PM EDT Tue Jul 9 2024
The remnants of Beryl are in the midst of an extratropical
transition this afternoon, as indicated by the presence of a robust
baroclinic leaf on satellite imagery. The remnant circulation is
centered over far southeastern Missouri at this moment, and looks
poised to push directly through central Indiana overnight.
More than plentiful moisture and ample forcing continue to be
expected as this occurs, with precipitable water values at or above
climatological maximum and strong midlevel deformation just
northwest of the low track, particularly this evening into early
overnight.
Storm total rainfall amounts will vary across the area, from near an
inch to as much as 3 inches with localized higher amounts. The
highest amounts are likely to be across the far northwestern
forecast area, including Lafayette metro, and the far
southern/southeastern forecast area, where a swath of up to 2 inches
or so appears likely given more opportunity for convection in that
area. Relatively dry antecedent conditions may limit a more
widespread flash flood threat and resultant longer term river flood
threat, though a localized flash flood threat definitely exists
through tonight. Will forgo a flood watch and continue to message
through other venues.
Plentiful deep layer and low level effective shear southeast of the
low track will present a concern for a tornado threat through this
evening, primarily across the southern/southeastern forecast area.
Late tonight into Wednesday, as the remnant low continues to
transition and pulls northeastward, a tightening pressure gradient
and strong low level flow is likely to result in windy conditions,
peaking during the daytime hours. Frequent wind gusts of 35-40 MPH
are likely, with a few gusts of 45-50 MPH possible. CAMs are quite
aggressive in this respect, but have shown some good skill in such
situations in the past. This may require a headline tonight, though
given lingering uncertainty and hydro/tornado threat for this
evening, will hold off on this.
&&
.LONG TERM (Wednesday night through Tuesday)...
Issued at 306 PM EDT Tue Jul 9 2024
While the remnants of Beryl dominate the short term focus, a trend
towards hotter and more humid conditions is anticipated through the
long range.
SYNOPTIC OVERVIEW
The current synoptic setup over the CONUS can be characterized by
troughing over the Plains. The trough, which is currently capturing
Beryl, will slowly propagate northeastward with time. It should
begin to flatten and exit off into the Atlantic by the weekend.
Thereafter, ensemble guidance shows a strengthening ridge taking
shape over the intermountain west. Neutral to at times trough-like
upper flow pattern looks to persist over the midwest and
northeastern US.
Closer to the surface, high pressure over the Atlantic (The Bermuda
High) is modeled to build westward into the southeastern US. This
should allow for a prolonged period of westerly to southwesterly low-
level flow over the Ohio River Valley and lower midwest.
Guidance shows occasional shortwave troughs / vorticity maxima
diving southeastward after cresting the western ridge. These may
occasionally bring rain/storm chances through much of the long
range. Spatial and temporal details still need to be worked out,
however. Guidance agrees on the first vort max to at least a
reasonable level, which looks to arrive on Thursday. As such, will
include a greater chance for showers and storms Thursday compared to
subsequent days. Upper-level flow looks weak, and CAPE diminishes
with eastward extent, so and showers and storms may be short-
lived/pulse-like in nature with a low severe risk. The greatest
likelihood would be west of Indianapolis and the greatest threat
would be sub-severe gusty winds.
EXPECTED WEATHER
In addition to the rain/storm chances mentioned above, we may see
occasional fog each morning through Saturday morning. Plenty of
moisture leftover from Beryl combined with good radiational cooling
potential should set the stage for this. A limiting factor would be
cloud cover associated with the Thursday trough.
Despite ridging well to our west, temperatures are expected to
increase under persistent southwesterly/westerly flow. Additionally
dew points should increase leading to heat indices into the 90s.
Temperatures are not anticipated to be excessively hot, but still a
bit above the climatological norm for this time of the year.
&&
.AVIATION (06Z TAF Issuance)...
Issued at 1230 AM EDT Wed Jul 10 2024
Impacts:
-MVFR to IFR cigs through 17Z
-Brief MVFR vsbys at LAF through 14Z with rain
-Wind shift from the southeast to northwest after 12Z
-Brief wind gusts to 40kts from 15Z to 22Z
Discussion:
Periodic light rain showers will continue at LAF, but otherwise
expect mostly dry conditions through the TAF period. Cigs will
gradually become MVFR to occasionally IFR from 09Z through 17Z with
a pretty sudden wind shift from the south to northwest towards 09Z-
12Z. Afterwards expect gusty winds through the day with brief gusts
to 40kts possible. These stronger winds should relax after 22Z.
&&
.IND WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
UPDATE...50
SHORT TERM...Nield
LONG TERM...Eckhoff
AVIATION...White
Source:
IND issues Area Forecast Discussion (AFD) at Jul 10, 12:31 AM EDT---------------
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