Forecast Discussions mentioning any of
"ACARS" "MDCRS" "AIRCRAFT" "TAMDAR" "AMDAR" "WVSS" received at GSD on 08/21/23
Area Forecast Discussion
National Weather Service Louisville KY
725 PM EDT Sun Aug 20 2023
...Updated Aviation Discussion...
.Short Term (Now through Monday)...
Issued at 310 PM EDT Sun Aug 20 2023
...Excessive Heat Warning NW of the I-64/I-65 Corridors This Week...
...Excessive Heat Watch Remains for Portions of Central KY...
Still seeing a few blips on radar from the mid level ACCAS showing
up on visible satellite imagery. Again, the inflow bases of these
showers are being convectively released around 600mb, so only
mentioning a chances of sprinkles out of the high bases across SW
Indiana. Otherwise, the main forecast focus will be on heat
headlines heading into the new work week.
Temperatures have climbed into the upper 80s and low 90s this
afternoon, and still have another couple hours to squeeze out a
degree or two more. This should still put most folks in the low 90s
for highs. Some cloud cover stretching NW from the Louisville Metro
up through Paoli could hurt temps just a bit, but overall looking
pretty good. Did want to note that forecast soundings and real time
aircraft soundings verified that we were only mixing to about 875-
900 mb today, so not quite getting the full effect from 850 mb temp
analysis, however we are still getting close to meeting expected
temps outside of a few cloud cover issues. That gives some
confidence that the deeper mixing and continually increasing 1000-
850 mb thickness days ahead should yield the mid and upper 90s mid
to late week.
Look for a mostly clear and quiet night, with perhaps some patchy
fog around. Look for lows in the low to mid 70s along and west of I-
65, with areas east of I-65 mainly in the upper 60s to around 70.
The 602 dm upper ridge centers over the lower Missouri River Valley
tomorrow, with increasing 1000-850 mb thicknesses and slightly
deeper mixing tomorrow. As a result, would expect to see another 2-3
degree rise from today`s highs. There is a pretty decent signal for
some decent upper sky cover tomorrow, especially across our NE CWA
which hurts confidence in how full of the potential heating we will
get. Nevertheless, the combination of low to mid 90s highs, and low
to mid 70s dew points should put areas along and west of I-65, and
along and north of I-64 (basically our NW CW) right around 105 for
afternoon peak heat indices. Given that this will be the 1st of at
least 4, if not 5 days, of expected Advisory criteria decided to
issue a duration-based Excessive Heat Warning in coordination with
PAH and surrounding offices. It is possible our SW KY counties will
flirt with 105 tomorrow afternoon as well, and may extend the
warning a little bit farther south toward the Bowling Green region
if enough confidence is gained.
East of the warning, will keep the Excessive Heat Watch going, and
even extend it eastward a tier of counties in anticipation of likely
needing additional headlines Tue through at least Thursday. Still
possible that these areas could need duration based products,
especially if Friday ends up being similar to Thursday. See long term
discussion for more details on that lower confidence day.
.Long Term (Monday Night through Saturday)...
Issued at 317 PM EDT Sun Aug 20 2023
---------------------------------------------------------------------
Key Messages:
- Hot and humid conditions with oppressive heat indices this week
- Relief from the heat and highs in the 80s by next weekend
---------------------------------------------------------------------
The focus through at least Friday remains the hot and humid weather
conditions. Strong expansive upper ridge will remain centered over
NE/IA/KS/MO at the start of the period then slowly weaken and drift
southward through midweek. Temperatures at 850mb look to be between
21-23C on Tuesday before higher values between 23-25C advect in from
the west-northwest for the second half of the week. Hottest day of
the week looks to be about Thursday but the challenge remains just
how hot will maximum temperatures get each day. NBM guidances
remains overcooked due to the high GFS values so decided to scale
back values just a bit keeping highs just below the century mark for
now. Other factors like potential cloud cover as well as some models
not showing the mixing level reaching the 850mb level went into
scaling temperatures back a touch. Even with these slight
adjustments, it will remain hot and with dew points in the low 70s
allowing apparent temperatures to reach and/or surpass 105F or each
day Tue-Thu. With daytime highs in the mid/upper 90s approaching
100, high heat indices and overnight lows around the mid 70s heat
headlines will continue through much of the forecast period.
Upper level low will work in across the PacNW Tues and move over the
northern peripheral of the upper ridge Wed & Thu along the
US/Canadian border before opening up into a shortwave trough by the
end of the week. This will help to flatten the ridge and even allow
it to retrograde slightly westward towards the end of the period.
While the deterministic models agree on this overall trend, they
differ on how deep the trough gets as it moves across the Great
Lakes. We do expect this to change the pattern and bring relief to
the heat for next weekend with highs dropping back into the 80s.
&&
.Aviation (00Z TAF Issuance)
Issued at 722 PM EDT Sun Aug 20 2023
Relatively quiet evening in store for our region, with VFR
conditions expected to continue through the period. A few SCT upper
clouds are noted near HNB, but otherwise a dry forecast will remain.
For the overnight, light and VRB winds and SKC should allow some
patchy fog development, mainly for HNB, but also possible for
BWG/LEX. Kept mention of 6SM BR for those three terminals, but
believe HNB would have the best chance of possibly seeing brief
MVFR near sunrise. Expect VFR tomorrow with mainly SCT upper clouds.
&&
.LMK WATCHES/WARNINGS/ADVISORIES...
KY...Excessive Heat Warning from 1 PM EDT /noon CDT/ Monday to 11 PM
EDT /10 PM CDT/ Thursday for KYZ023>026-030.
Excessive Heat Watch from Monday afternoon through Thursday
evening for KYZ027>029-031>034-038-045-053-061>063-070>074.
IN...Excessive Heat Warning from 1 PM EDT /noon CDT/ Monday to 11 PM
EDT /10 PM CDT/ Thursday for INZ076>078-083-084-089>092.
Excessive Heat Watch from Monday afternoon through Thursday
evening for INZ079.
&&
$$
Short Term...BJS
Long Term...BTN
Aviation...CJP