107
FXUS64 KLIX 162331
AFDLIX

Area Forecast Discussion
National Weather Service New Orleans LA
631 PM CDT Fri Aug 16 2024

...New AVIATION...

.SHORT TERM...
(This evening through Saturday night)
Issued at 255 PM CDT Fri Aug 16 2024

Convective development has been noted across the area over the
past hour or two, mainly along the lake and sea-breeze boundaries.
This was a little earlier than expected but the lack of northerly
flow aloft (especially across the southshore) and PW around 2.1
helped kick things off a little earlier than expected. A slight
pocket of dry air between 500mb and 700mb is aiding in ample DCAPE
across the area for these storms to work with. This has
contributed to values upwards of 1100 j/kg across the area,
supporting an isolated damaging wind risk with any storm that gets
a strong core. The stronger the core, the more downward momentum
it will have with that dry air in place. Something else also
working for the strong gusty wind risk is the very high freezing
level, which is around 16kft. This will support decent melting of
the stronger core, promoting evaporational cooling and more
downward momentum. So, to sum things up, expect isolated strong to
severe winds in the strongest storms this afternoon and evening.
Any convection that does form should dissipate shortly after
sunset as we lose daytime heating.

Tomorrow will be similar to today as the higher moisture content
hangs around the area for one more day. PW will remain above the
75th percentile at around 2.1, so this, along with the departing
ridge to the west will support coverage similar to today. Much of
the coverage will be dictated by lake and sea-breeze boundaries
once again during the afternoon and evening timeframe. With the
ridge sliding to the west more tomorrow, we will be more firmly in
northerly flow aloft. Typically for northerly flow, convective
development is later in the afternoon and evening, so temps were
bumped up a little bit to account for the extra heating expected
before convection starts tomorrow. DCAPE will still be elevated
across the area in the 1100-1200 j/kg range due to that same patch
of dry air mentioned for today. Thus, strong to severe winds are
possible again with any strong storm that forms tomorrow. Similar
to today, any convection that forms should dissipate after sunset
around 9 or 10pm.

Outside of convection, although the upper-level ridge will be
departing to the west, the surface high over the SE CONUS will
continue to filter over the area tomorrow. This will cause temps
to slightly high than today. As mentioned before, convective
development will play a big role in high temperatures tomorrow, so
since it is expected to happen a little later, we should reach
heat advisory criteria during the late morning and afternoon
tomorrow.

&&

.LONG TERM...
(Sunday through Thursday night)
Issued at 255 PM CDT Fri Aug 16 2024

The aforementioned surface high will become centered over the area
by late Saturday and Sunday. At the same time, a pocket of very
dry air above 850mb will filter into the area from the north on
the perifery of the mid-level ridge, causing PW to drop to around
1.6-1.7 inches (which is below the median for that day). The
surface high combined with the upper-level dry air filtering in
will cause lower rain chances and much higher temperatures. An
excessive heat watch will likely be issued by tomorrow morning for
Sunday due to the expected heat indices from 110-115 during the
afternoon.

Models seem to agree that a backdoor cold front will make its way
across the SE CONUS Sunday and into the beginning of next week in
response to troughing over that region. This is definitely a good
sight to see in August, but the one thing to watch for is an MCS
that comes along with it. If this were to occur, it would be at
some point on late Sunday or Monday morning. The NAM tries to
show some semblance of a complex moving through, but low-level dry
air and unfavorable diurnal timing seems to be against any
complex. If one does make it through the area, gusty winds will be
the primary risk.

Beyond Monday, very dry mid-level air behind the front will filter
into the area. This will cause PW values to be lower than the 25th
percentile on Tuesday and near the daily minimum on Wednesday.
Needless to say it will be fairly dry across the area beyond
Monday, but at least dew points are expected to be in the 60s, so
it will not feel nearly as oppressive.

&&

.AVIATION...
(00Z TAFS)
Issued at 627 PM CDT Fri Aug 16 2024

Isolated TSRA over downtown New Orleans will necessitate carrying
VCTS for the first hour or two of the KNEW/KMSY forecasts until it
dissipates. May need an amendment for KBTR if storms do not
dissipate to their north in the next hour or so. Aside from that,
generally VFR conditions through the forecast period. Confidence
in development of TSRA tomorrow is not high enough to justify
carrying in the forecast.

&&

.MARINE...
Issued at 255 PM CDT Fri Aug 16 2024

Mostly benign marine conditions will continue throughout the
forecast period. Daily isolated to scattered rain chances remain
mainly during the early morning timeframe each day. A surface high
will set up over the area late Saturday and into Sunday, keeping
winds calm. Then, a backdoor cold front is expected to at least
make it into the area by Monday. So, expect slightly elevated
northerly winds with the front before slacking off when the
following surface high settles over later in the week.

&&

.PRELIMINARY POINT TEMPS/POPS...
MCB  75  97  74  99 /  20  30  10  10
BTR  79  99  79 101 /  10  30   0  10
ASD  78  96  78  99 /  10  30   0  20
MSY  80  96  79  99 /  10  30   0  10
GPT  79  93  79  97 /  10  30  10  20
PQL  78  97  77 100 /  10  20  10  30

&&

.LIX WATCHES/WARNINGS/ADVISORIES...
LA...Heat Advisory until 7 PM CDT this evening for LAZ034>037-039-
     046>048-056>060-064>071-076>090.

     Heat Advisory from 10 AM to 7 PM CDT Saturday for LAZ034>037-039-
     046>048-056>060-064>071-076>090.

GM...None.
MS...Heat Advisory until 7 PM CDT this evening for MSZ068>071-077-
     083>088.

     Heat Advisory from 10 AM to 7 PM CDT Saturday for MSZ068>071-077-
     083>088.

GM...None.
&&

$$

SHORT TERM...JZ
LONG TERM....JZ
AVIATION...RW
MARINE...JZ