Area Forecast Discussion
Issued by NWS New Orleans/Baton Rouge, LA

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FXUS64 KLIX 042004

Area Forecast Discussion
National Weather Service New Orleans LA
304 PM CDT Wed Oct 4 2023


(This evening through Friday night)
Issued at 249 PM CDT Wed Oct 4 2023

An upper trough is broadening while moving east across the
midsection of the country while the southern apex of it lags behind
to some degree. This is starting the erosion process of the northern
side of the upper ridge that encompasses the Gulf Coast to the
Northeast US. Low level moisture from easterly flow across the Gulf
is increasing and bringing slightly hazy conditions over southern
portions of the CWA. This will continue through tonight into
Thursday morning. Not thinking impactful fog, but will be noticeable.

The real changing will be coming late Thursday into Friday. A cold
front embedded within the base of the approaching trough should be
moving through east Texas and just nudging into far NW LA Thursday
morning and reaching into the local forecast area Thursday night into
Friday morning. Showers and possibly a few isolated thunderstorms
will pass across the region as the boundary comes through Friday.
Minimal instability and shear means not looking at anything remotely
severe or even strong. Coverage will probably decrease as the day
progresses with much of the rain shifting to coastal areas late in
the day to the overnight period. Pretty good consensus between GFS
and CAMs that this will be the case, but still some models
suggesting a slower progression of activity. Thus, latest POPs
account for that slower potential with scattered showers hanging on
until later Friday night. The same goes for temps. With earlier
arrival of the boundary and shower/cloud activity, will have highs
limited to lower/mid 80s on Friday.


(Saturday through Tuesday)
Issued at 249 PM CDT Wed Oct 4 2023

Deep layer northwest flow on the backside of a strong longwave
trough axis will dominate the area through the weekend. On the
back of this northwest flow regime, a much colder and drier
airmass will advect into the region. This will result in clear
skies and cooler than average temperatures for both Saturday and
Sunday. Model sounding analysis indicates that 925mb temperatures
will only peak in the mid to upper 50s over the area, and this is
supportive of daytime highs only warming into the mid to upper 70s
on both Saturday and Sunday. These readings are a good 5 degrees
below average for this time of year. The combination of dry air
and clear skies will also support strong radiational cooling each
night, and expect to overnight lows dip into the upper 40s and
lower 50s for areas along and north of the I-10/12 corridor. Lows
will dip into the upper 50s and lower 60s south of Lake
Pontchartrain and along the immediate coast of Louisiana.

By Monday and Tuesday, the longwave trough over the eastern third
of the CONUS will begin to lift out, and a more zonal flow regime
will take hold of the Gulf South. The main impact from this more
zonal flow regime will be a gradual increase in daytime highs back
to more average readings in the low to mid 80s. Little in the way
of moisture advection is expected as northerly flow persists in
the low to mid-levels on the eastern side of a mid-level ridge
axis, and this will support continued large diurnal temperature
ranges. Lows will easily fall into the 50s over inland areas and
the lower 60s south the lake and along the coast Monday night.


(18Z TAFS)
Issued at 249 PM CDT Wed Oct 4 2023

Latest observations across the region show a mix of VFR and MVFR
conditions, mainly due to visibilities. This will continue through
the rest of this afternoon and overnight hours as low level moisture
increases. The latest forecast accounts for this plus possibly some
isolated to scattered showers Thursday morning at a few terminals.

Issued at 249 PM CDT Wed Oct 4 2023

The pressure gradient that was supporting Exercise Caution
conditions is beginning to relax. So have let that headline expire.

First significant cold front of the fall season still looks to come
marching through Friday night. Expecting Small Craft conditions to
develop behind the front. Probably looking at a 24 to 36 hour
duration of those conditions before the gradient relaxes.


MCB  65  89  66  84 /   0  20  40  20
BTR  69  92  70  88 /   0  30  40  20
ASD  68  89  70  86 /   0  20  60  30
MSY  73  89  74  85 /   0  20  60  40
GPT  70  86  70  86 /   0  20  60  30
PQL  66  89  68  87 /   0  10  50  40


LA...Coastal Flood Advisory from 7 PM this evening to 7 AM CDT
     Thursday for LAZ067>070-076-078.

MS...Coastal Flood Advisory from 7 PM this evening to 7 AM CDT
     Thursday for MSZ086.



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