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

Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41
FXUS64 KLIX 040425 AAB

Area Forecast Discussion...UPDATED
National Weather Service New Orleans LA
1125 PM CDT Tue Oct 3 2023


(This evening through Wednesday night)
Issued at 255 PM CDT Tue Oct 3 2023

Current upper level pattern in place across the country is fairly
simple in the fact that there`s a broad ridge extending from the
Gulf of Mexico to the Great Lakes and a deep longwave trough draped
across the Rockies. Strong subsidence from this high pressure and
very dry air throughout the atmospheric column locally will keep the
land areas of the CWA rain free. The only exception in along the LA
coastal areas where surface dewpoints are in the mid 70s and there`s
a sharp gradient of higher deeper moisture content with PW`s over
1.5". Temps continue to be at or slightly above normal due to upper
ridge nearby and relatively dry air in place.

The upper trough to the northwest will broaden across the
Canadian/US border on Wednesday while the southern apex of it lags
behind in eastward progression. This will cause the northern side of
the upper ridge to erode but still have some semblance of high
pressure aloft to keep most of the CWA from seeing any rainfall
outside of continued coastal showers. Also won`t see appreciable
chances in temperatures from the last several days. Not much spread
in guidance so stayed with deterministic NBM. A cold front embedded
within the base of the approaching trough should be moving through
east Texas and just nudging into far NW LA by the end of this
forecast period, 12Z Thursday. Model consensus fairly high at this
point that it won`t reach the CWA before then, so have kept POPs out
of the forecast for now.


(Thursday through Monday night)
Issued at 255 PM CDT Tue Oct 3 2023

No significant changes in thinking from previous forecasts. A strong
northern stream trough axis will dig into the eastern half of the
CONUS on Friday and Saturday.  An attendant cold front will
accompany this trough axis with the frontal passage expected to
occur during the day on Friday.  Modest moisture return as evidenced
by PWATS of around 1.75 inches in advance of the front will support
the development of some scattered shower and weak thunderstorm
activity.  This is reflected by PoP values of 30 to 40 percent over
most of the CWA. In fact, model sounding analysis indicates very
limited mid-level instability, so any thunderstorm activity should
remain isolated and be very short-lived.  By Friday night, a surge
of much drier air is expected to begin sweeping into the area, and
this will effectively shut off any rain chances by Saturday morning.
As deep layer northwest flow and strong negative vorticity advection
takes hold over the weekend, clear skies and low humidities can be
expected from Saturday through early next week.

Little spread in the model solutions exists in terms of temperature
forecasts on Friday and Saturday, and have largely stuck with the
deterministic NBM output through this period.  Daytime highs on
Friday should be near average in the mid 80s, but colder air will
begin to advect into the region Friday night. This colder airmass
will push 925mb temperatures into the upper 50s, and this support
daytime highs at the surface in the upper 70s. A gradual
modification of the airmass is expected by Monday and Tuesday, but
daytime highs will remain below average in the lower 80s. The
combination of clear skies, dry air, and light winds will allow
overnight lows will dip into the 50s over most of the forecast area
Saturday, Sunday, and Monday nights. However, a few locations in
southwest Mississippi and in the drainages of the Pearl and
Pascagoula Rivers could dip into the upper 40s.  To the south of
Lake Pontchartrain, northerly winds off the warmer lake waters will
keep temperatures more modified in the lower 60s each night.
Overall, a very pleasant stretch of weather is expected after the
front pushes through on Friday.


(06Z TAFS)
Issued at 1123 PM CDT Tue Oct 3 2023

Mostly VFR conditions anticipated through this TAF cycle. BTR,
HUM, and MCB will have an opportunity to drop into the MVFR range
for visibility by around sunrise. Any shallow fog should
dissipate shortly after sunrise allowing for mostly clear skies
once again. Otherwise, light easterly or southeasterly winds
anticipated through the early morning. Winds should become more
moderate (generally 10-15kts) by mid to late morning and continue
through around sunset/00z Thurs. (Frye)


Issued at 255 PM CDT Tue Oct 3 2023

There`s a strong surface ridge situated underneath a broad upper
ridge centered northeast of the CWA. To the northwest, a surface
trough is deepening while tracking into the Rockies. This is
resulting in a tight pressure gradient across the local coastal
waters. That gradient currently supports Small Craft Advisory winds
in open Gulf waters with Exercise Caution conditions in the tidal
lakes and sounds. However, the gradient will start to relax some
this evening and tonight as the surface ridge slides east. Thus, the
SCY will drop off and just carrying SCS headline through tonight.

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  91  63  91  65 /   0   0   0   0
BTR  93  67  93  69 /  10   0   0   0
ASD  89  65  90  67 /  10   0   0   0
MSY  89  72  89  73 /  10   0   0   0
GPT  86  66  86  69 /   0   0   0   0
PQL  89  62  90  66 /   0   0   0   0


LA...Coastal Flood Advisory until 7 AM CDT Wednesday for LAZ067>070-

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

MS...Coastal Flood Advisory until 7 AM CDT Wednesday for MSZ086.

     Coastal Flood Advisory from 7 PM Wednesday to 7 AM CDT Thursday
     for MSZ086.



MARINE...ME is the U.S. government's official web portal to all federal, state and local government web resources and services.