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

Home | 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 42 43 44 45
000
FXUS64 KLIX 121720
AFDLIX

Area Forecast Discussion
National Weather Service New Orleans LA
1220 PM CDT Tue Mar 12 2024

...New AVIATION...

.SHORT TERM...
(Today through Wednesday)
Issued at 320 AM CDT Tue Mar 12 2024

Surface high pressure over the southeastern quarter of the country
early this morning with quasi-zonal mid-level flow. One shortwave
moving through that flow has passed just to the east of the area
over the last few hours, with another trough from Colorado to Baja
California. Locally, satellite loops showed scattered to broken
mid level clouds across the area associated with the shortwave
passing to the east. Early morning temperatures generally ranged
from the mid 40s to mid 50s.

With the high pressure now to the east, winds will gradually
become southeast to south today and start to increase low level
moisture. Dew points probably won`t respond much until late in the
day, and have undercut the NBM deterministic dew points a bit,
between the 25th and 50th percentile.

The trough to the west is forecast to move across the area during
the day on Wednesday. There may be just enough moisture available
(precipitable water 1.0-1.25 inches) to produce a few showers and
perhaps a rumble or two of thunder during the afternoon, but
widespread rainfall isn`t anticipated at this time.

Didn`t make significant adjustments to NBM temperatures in the
short range as for the most part, not much variation in guidance.
Where there was, the NBM deterministic tended toward the higher
guidance on high temperatures.

&&

.LONG TERM...
(Wednesday night through Monday)
Issued at 320 AM CDT Tue Mar 12 2024

Upper trough is forecast to cut off over the Desert Southwest by
late in the week, and remain there through the weekend into early
next week. That will turn the mid level flow more southwesterly by
late in the week. A northern stream shortwave moving through the
Great Lakes will push a front toward the area by Friday, but as
the front becomes parallel to the mid level flow over the Lower
Mississippi River Valley, it will become nearly stationary for
several days. Shortwave energy moving through the southern stream
will produce several rounds of showers and thunderstorms, but the
global models aren`t in particularly good agreement regarding
timing of the shortwaves, nor where the frontal boundary becomes
situated. GFS and its ensemble tend to keep most of the
significant rainfall to the north of the local area, while the
ECMWF tends further south. For now, will hang with the NBM PoPs,
understanding that some adjustments will be necessary for some
portions of the area. The frontal boundary is likely to become a
focus for heavy rainfall later in the week, with the GFS based
solutions somewhat more favored at this point by WPC. The GFS
based solutions would also be a bit more favorable for strong
thunderstorms during the afternoon hours from Thursday into the
weekend with favorable instability, although shear appears to be a
bit limited.

One other concern would be at least some potential for advection
fog later in the week. Water temperatures are generally in the
lower and middle 60s, except for the Mississippi River, which is
in the mid and upper 50s. Dew points aren`t expected to be
sufficient for fog away from the river waters Wednesday night, but
are expected to be in the mid and upper 60s by Thursday night.
Forecast dew points would indicate at least some potential near
the coast through at least Saturday night before the front
progresses far enough south to limit the threat.

With the lack of confidence in details of frontal positioning each
day, the temperature forecast will remain close to the NBM, which
is generally above normals through the weekend, with temperatures
cooling to a bit below normal early next week.

&&

.AVIATION...
(18Z TAFS)
Issued at 1216 PM CDT Tue Mar 12 2024

VFR conditions prevail at all area airports and will persist
through the forecast period. Some clouds will start to move in
tonight into tomorrow with some lower ceilings, but no category
changes expected. MSW

&&

.MARINE...
Issued at 320 AM CDT Tue Mar 12 2024

Onshore flow will become more prominent today and continue through
most or all weekend. There may be a few periods Thursday and or
Friday where winds exceed 15 knots briefly, but are expected to
remain below advisory criteria. Winds may become strong enough for
advisories early next week behind the cold front, but that`s
beyond the marine forecast range at this point.

There is at least some threat for sea fog as we get out to around
Thursday or Thursday night as very moist air moves across cooler
waters. The fog may onset first near the mouth of the Mississippi
River where water temperatures are in the upper 50s. Fog may be a
factor through the weekend in portions of the waters, and we`ll
continue to monitor the threat.

&&

.PRELIMINARY POINT TEMPS/POPS...
MCB  51  76  61  78 /   0  20   0  50
BTR  58  80  66  84 /   0  30  10  40
ASD  55  77  63  80 /   0  20  10  40
MSY  59  77  66  80 /  10  20  10  50
GPT  54  74  62  76 /   0  10  10  40
PQL  51  77  61  79 /   0  10  10  40

&&

.LIX WATCHES/WARNINGS/ADVISORIES...
LA...None.
GM...None.
MS...None.
GM...None.
&&

$$

SHORT TERM...RW
LONG TERM....RW
AVIATION...MSW
MARINE...RW


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