LIX issues Area Forecast Discussion (AFD) at Aug 18, 9:57 PM CDT ...New UPDATE...801
FXUS64 KLIX 190257
AFDLIX
Area Forecast Discussion
National Weather Service New Orleans LA
957 PM CDT Sun Aug 18 2024
...New UPDATE...
.UPDATE...
Issued at 949 PM CDT Sun Aug 18 2024
A strong outflow boundary associated with a weakening line of
thunderstorms currently sweeping through portions of central
Mississippi will begin to impact Southwest Mississippi in the
next hours. Based on the expected time of arrival of the outflow
boundary and associated weakening convective line, have increased
PoP values to 40 to 50 percent for this area. The biggest impact
will be gusty winds of around 40 mph as the outflow boundary
sweeps through closer to 11 pm. The impacts from the outflow
boundary and line will diminish as the system enters southeast
Louisiana and continues to weaken. However, there is the potential
for additional development along the stalling outflow boundary as
it slowly sinks southward late tonight into early tomorrow
morning, and now have a 30 to 40 percent chance of convective
development along the I-10 corridor after 3 am this morning. PG
&&
.SHORT TERM...
(This evening through Monday night)
Issued at 230 PM CDT Sun Aug 18 2024
Another hot day across the region. In fact, a little under an hour
ago here at the WFO LIX hit a heat index of 116F. These types of
numbers are common across the region with the Excessive Heat
Warning remaining in effect areawide. Low level moisture has been
tough to mix out today due in part to moisture pooling ahead of a
backdoor cold front moving generally toward our region from the
Tennessee and mid MS River Valley. This front should make it
through the region tonight and along with it we still cannot rule
out some isolated shower or storm activity later this evening
especially over the MS Gulf Coast or interior south MS. Parameters
are supportive of a strong wind gust or two and perhaps some
lower-end hail in the most robust updrafts. Coverage is
questionable due to an excessive amount of dry air, which is the
main limiting factor to the overall conditional severe weather
potential.
Eyes will shift upstream later tonight and into Monday morning.
Globals and most mesoscale models are developing an MCS over the
Ozarks, which when caught in the northerly flow drops due south
along the surface boundary. Nearly all forecast guidance want to
decay this feature as or just before it moves into the western
portions of the forecast area Monday morning or early afternoon.
Given timing this seems to be the most likely solution. However,
the NAM is pushing the MCS through generally along and west of
I55. Given that the feature is likely to develop there is just
enough signal to keep lower-end POPs in the forecast respectively.
With that, if the MCS maintains we could see a strong wind gust or
two...but that is a BIG IF.
Temperatures tomorrow will be interesting and there is some
uncertainty lingering in there especially with any cold pool that
develops from the potential MCS. Even if the MCS doesn't arrive
the outflow or cold pool still might. This would disrupt the high
temp forecast. That said, there are more signs that we will not be
lucky enough for that so kept the previous maxT forecast going.
Also, dry air does start to filter into the region generally north
of the I10/12 corridor. Regardless of TEMP, with the lower
humidity there will not be a need for a heat headline for these
areas on Monday. However, moisture will remain rather firm closer
to the frontal boundary and tidal lakes so south of I10 a heat
advisory was issued. But again, the temperature forecast is
dependent on the MCS/cold pool. (Frye)
&&
.LONG TERM...
(Tuesday through Saturday night)
Issued at 230 PM CDT Sun Aug 18 2024
Tuesday and going into the middle part of the new workweek we will
reside under a mostly dry northerly flow aloft on the eastern
periphery of a strong 598dam ridge over the Texas Panhandle or
desert southwest. The residual boundary looks to remain generally
over central parts of Louisiana (north to south). That said, the
very dry boundary layer should keep rain chances in check, at
least over the landbased zones. Marine, maybe some isolated
diurnally driven convection. Otherwise, temperatures will still be
above average, but with dewpoints dropping, especially during the
afternoon hours with proper mixing, the heat will be slightly more
tolerable with heat index values at rough or just slightly higher
than the actual temp.
Going into Thursday and beyond, globals are in good agreement that
the trough across the eastern U.S. begins to pinch off into a mid
and upper level low. As this feature drops southward over the
Gulf, shower and storm chances increase again. At the surface,
low level moisture gradually works back into the area and with a
bit cooler temps aloft with the weak ULL, the convective coverage
should by a bit more numerous going into Friday and especially
the upcoming weekend. (Frye)
&&
.AVIATION...
(18Z TAFS)
Issued at 1210 PM CDT Sun Aug 18 2024
VFR conditions expected through the cycle. Low convective chances
this evening for the MS Gulf Coast terminals...covered with VCs.
Winds will generally remain northerly and less than 10 knots
through the period. (Frye)
&&
.MARINE...
Issued at 230 PM CDT Sun Aug 18 2024
Overall favorable marine conditions continue outside of any
potential showers or storms. Naturally, convection will increase
winds and seas locally. Otherwise, a surface front will eventually
push into the local waters to start the new workweek. Outside of
the chance of additional shower and thunderstorm activity, winds
will turn more to the north or northeast Monday and into Tuesday.
Lower-end cautionary headlines will be possible early next week,
especially for the MS Sound areas. High pressure will eventually
take back over late in the period and allow winds to shift back to
a more southeasterly direction. (Frye)
&&
.PRELIMINARY POINT TEMPS/POPS...
MCB 75 93 70 92 / 40 20 10 10
BTR 80 97 76 96 / 20 30 20 10
ASD 78 96 73 96 / 30 20 10 10
MSY 81 96 79 94 / 30 50 10 20
GPT 78 96 74 94 / 30 20 10 10
PQL 77 99 71 97 / 30 10 10 10
&&
.LIX WATCHES/WARNINGS/ADVISORIES...
LA...Heat Advisory from 10 AM to 7 PM CDT Monday for LAZ034-046-
056>060-064>070-076>078-080-082-084>090.
GM...None.
MS...None.
GM...None.
&&
$$
SHORT TERM...RDF
LONG TERM....RDF
AVIATION...RDF
MARINE...RDF
Source:
LIX issues Area Forecast Discussion (AFD) at Aug 18, 9:57 PM CDT ...New UPDATE...---------------
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