IND issues Area Forecast Discussion (AFD) at Aug 4, 10:01 PM EDT504
FXUS63 KIND 050201
AFDIND
Area Forecast Discussion
National Weather Service Indianapolis IN
1001 PM EDT Sun Aug 4 2024
.KEY MESSAGES...
- Mostly Clear Tonight; Patchy Fog possible.
- Mostly Sunny and Hot on Monday.
- Chance of thunderstorms Tuesday and Tuesday Night
- Not as hot and less humid Wednesday through next weekend
&&
.FORECAST UPDATE...
Issued at 1000 PM EDT Sun Aug 4 2024
The quieter, yet rather stagnant pattern will continue over central
Indiana tonight, under broad and weak surface high pressure
stretched across much of the eastern half of the CONUS. Synoptic-
scale gradients retracted well to our north will promote another
humid night with slightly above normal temperatures and more
importantly small dewpoint depressions. Lack of forcing will
promote mostly clear skies, light and variable winds...and therefore
increasing chances of fog.
Fog should be mainly patchy, yet the favorable combination of
factors may promote visibilities locally below 1 SM in the pre-dawn
hours. Should be some SCT mid/high clouds rolling across northern
zones later tonight which would favor southern counties for better
fog organization. Dewpoints will once again guide overnight lows
with readings dropping to around 70F across the realm.
&&
.SHORT TERM (This evening through Monday)...
Issued at 235 PM EDT Sun Aug 4 2024
Synopsis -
Surface analysis early this afternoon shows shows a broad area of
high pressure stretching from Southern MO, across TN/KY to NC/VA.
Winds were light to calm across Central Indiana. A slow moving
frontal boundary was found stretching from IA across WI/MI to
southern Ontario. GOES Imagery shows a an area of clouds on the
north side of this front. Otherwise, SCT CU was found across
Indiana. Aloft, strong high pressure in was place over the western
CONUS, with northwest flow the northern plains into the Ohio Valley.
The best subsidence across the area had moved to southern Indiana,
Kentucky and the deep south. Dew points across Central Indiana
remained quite high, in the upper 60s and lower 70s.
Tonight -
Little overall change will be expected in the weather tonight.
Indiana will remain under the influence of the strong area of high
pressure in across the area. Aloft the northwest flow will remain in
place, with little in the way of forcing dynamics passing across the
area. Forecast soundings show a dry column as mainly subsidence
looks to remain in play. Thus mostly clear skies and light winds
will be expected. Again with dew points in place across the area in
the upper 60s to around 70, dew point depressions will once again be
low, 1-2F, allowing for patchy fog development. Look for lows near
persistence, in the upper 60s to around 70.
Monday -
A slight change in the weather is expected on Monday. It will be
hotter.
Models suggest that the frontal boundary to the north will begin to
sag southward. This will allow a thermal ridge ahead of the boundary
to sag southward across Central Indiana on Monday. 850MB temps are
suggested to rise to near 20C by Monday afternoon. This is a few
degrees warmer than the air mass across our area today. The result
will be warmer temperatures, with many locations getting into the
90s. Elsewhere in the pattern, the surface high remains anchored to
our south, allowing a light and warm westerly surface wind. Again,
the northwest flow aloft remains predominate with little in the way
of forcing dynamics available. Forecast soundings continue to
suggest a dry column and with a warmer air mass expected, and CU
development should be less likely with higher convective
temperatures. Thus a mostly sunny and hot day is expected.
&&
.LONG TERM (Monday night through Sunday)...
Issued at 235 PM EDT Sun Aug 4 2024
The long term will start off with Debby moving slowly northeast over
the Florida/Georgia line Monday night even as a dome of high
pressure, across the Rockies, results in northwest flow over the
Great Lakes and Ohio Valley. At the surface, broad high pressure
will keep most or all of central Indiana dry through Monday night.
The exception will be overnight, when deeper moisture over the Great
Lakes along with a back door front could trigger some convection
over our northern and eastern counties. Tuesday may not be quite as
hot and humid, at least over northeastern sections as a surface wave
dips southeast and drags a cold front across central Indiana Tuesday
night. Moderate to strong instability and a moist column to around
10K feet per soundings, combined with the synoptic forcing could
trigger more convection into Tuesday night. With 0-6km Bulk Shear to
possibly 40 knots at times, combined with the unstable atmosphere, a
few storms could be severe, mainly Tuesday afternoon and night. Lack
of good low level inflow, tornadoes will not be a big concern, but
with wet bulb zeroes to around 13K feet, large hail could be a
concern in addition to damaging winds.
The passage of the cold front will bring cooler and drier weather to
central Indiana through the rest of the week and weekend, reinforced
by a moisture starved front Thursday night. Model consensus has
temperatures a few degrees below normal with highs in the upper 70s
to middle 80s. Perhaps even more noticeable will be the dew points,
that will likely return to the lower to middle 60s from the current
air mass that has been producing dew points in the 70s.
.
The upper pattern strong
favors that the remnants of Debby will not be a concern to central
Indiana but rather to the east coast in the form of periods of heavy
rainfall and potential flooding.
&&
.AVIATION (00Z TAF Issuance)...
Issued at 736 PM EDT Sun Aug 4 2024
Impacts:
- MVFR/possible IFR visibility expected from patchy fog outside of
KIND 10-13Z Monday
Discussion:
VFR conditions under broad yet very weak surface high pressure will
be the rule this evening and into the overnight. Mostly clear skies,
light/variable winds and low dewpoint depressions will, however,
promote development of at least patchy fog late tonight. MVFR
visibility is certainly possible at all TAF sites outside of
KIND, with potential for IFR VIS greatest at KHUF/KLAF.
VFR should return to all terminals by 13-14Z Monday ahead of a
modest rebound in west-southwesterly flow to mainly 3-6KT sustained
winds.
&&
.IND WATCHES/WARNINGS/ADVISORIES...None.
&&
$$
UPDATE...AGM
SHORT TERM...Puma
LONG TERM...MK
AVIATION...AGM
Source:
IND issues Area Forecast Discussion (AFD) at Aug 4, 10:01 PM EDT---------------
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