387
FXUS64 KLIX 171858
AFDLIX

Area Forecast Discussion
National Weather Service New Orleans LA
158 PM CDT Mon Aug 17 2026

...New SHORT TERM, LONG TERM, AVIATION, MARINE...

.KEY MESSAGES...
Updated at 148 PM CDT Mon Aug 17 2026

- Dangerous heat continues with afternoon heat indices commonly
  reaching 110115F. Warm overnight temperatures will offer
  limited relief.

- Only isolated to scattered afternoon storms are expected the
  next couple days. Coverage should be somewhat greater toward
  the Mississippi coast and eastern portions of the forecast area.

&&

.SHORT TERM...
(Now through Thursday night)
Issued at 148 PM CDT Mon Aug 17 2026

Heat remains the primary forecast concern through the short term as
a broad mid/upper-level ridge centered near the Four Corners
continues to be extend eastward across the Lower Mississippi Valley
and Gulf Coast. The local area remains within the eastern periphery
of the ridge rather than beneath its strongest subsidence, which
will allow at least some convection each afternoon. However, the
combination of a warm low/mid-level thermal profile, generally weak
west to northwest low-level flow, and limited large-scale ascent
will continue to favor well above normal temperatures and only
modest convective relief. With little thermal profile change for
Tuesday, have issued an Extreme Heat Warning for the Mississippi
Coast and Louisiana parishes around Lake Pontchartrain...Heat
Advisory elsewhere.

Isolated to scattered convection will be possible this afternoon
along the sea breeze, lake breeze and any differential-heating
boundaries. Coverage should be somewhat greater across the
Mississippi coast and eastern portions of the forecast area, where
the influence of the upper ridge is weaker, with lower coverage
farther west toward Baton Rouge and the Atchafalaya Basin. POPs
generally in the 20 to 40 percent range appear reasonable through
mid week, highest east. Any storm will be capable of briefly
knocking temperatures down considerably, but the localized nature
and relatively late timing of convection will provide little area-
wide relief from the heat. A few storms could also produce brief
gusty winds given the dry air noted aloft.

By Wednesday and Thursday, troughing digging southward across the
eastern United States should begin to erode the eastern side of
the upper ridge. The change is gradual rather than abrupt, so
substantial cooling is not expected immediately. However, slightly
lower heights, a little more moisture and increasing
opportunities for mesoscale boundaries should support a modest
upward trend in afternoon convection. This should begin to shave a
degree or two off daytime temperatures in some areas,
particularly across the eastern half of the CWA and near the
coast. Interior western portions of the area will likely remain
the hottest and driest.

&&

.LONG TERM...
(Friday through Sunday night)
Issued at 148 PM CDT Mon Aug 17 2026

The broad-scale pattern becomes somewhat less favorable for
persistent excessive heat in the later half of the week and over the
weekend as the eastern portions of the Four Corners ridge is eroded
by an eastern U.S. trough. This should gradually weaken the ridge
aloft locally and allow somewhat greater convective coverage
compared with the first half of the week. For this reason, a
completely flat temperature forecast through late week into the
weekend appears less likely than at least modest cooling. Heat
indices around or above 108 degrees will become more and more
confined to areas near the coast where daytime dewpoints hold a bit
better than those farther inland that are able to mix out better.

By Saturday and Sunday, a combination of slightly lower mid-level
heights, increasing clouds and a somewhat better chance of afternoon
convection should trim daytime highs by a few degrees in at least
portions of the area. Rain chances should trend upward into the
chance category for more of the area Friday thru Sunday, with the
greatest coverage generally favored across the eastern and coastal
portions of the CWA. Not looking at widespread convection and
substantial day-to-day variability will remain dependent on
mesoscale boundaries and the evolution of the weakness over the
eastern Gulf.

That eastern Gulf feature, which is at the base of the trough over
the eastern US, is also the primary source of uncertainty for the
weekend. A farther west evolution would produce greater rain
coverage, more cloud cover and a more noticeable reduction in
afternoon temperatures. If it instead remains east of the area and
is absorbed into the larger eastern U.S. trough, stronger ridge
influence would linger locally and temperatures could remain on the
warm side of guidance. At this time, a gradual increase in
convection and modest reduction in afternoon heat appears to be the
most reasonable middle ground rather than either a major pattern
change or uninterrupted extreme heat through the entire weekend.

MEFFER
&&

.AVIATION...
(18Z TAFS)
Issued at 148 PM CDT Mon Aug 17 2026

VFR conditions will dominate the forecast outside of convection.
Isolated to scattered thunderstorms are possible during the
afternoon, with the greatest potential at eastern and coastal
terminals. Direct impacts remain too localized for prolonged
restrictions, but any terminal affected by a storm could briefly
experience IFR visibility in heavy rainfall along with gusty and
variable winds. Convection should diminish during the evening with
mainly VFR conditions overnight. A similar pattern is expected
Tuesday.

MEFFER
&&

.MARINE...
Issued at 148 PM CDT Mon Aug 17 2026

Surface high pressure centered over the central Gulf will maintain a
generally weak pressure gradient through much of the period. A
predominantly westerly flow regime will continue, with a typical
summertime diurnal fluctuation in both direction and speed. Winds
should generally increase during the overnight and early morning
hours to around 10 to 15 knots before relaxing to around 5 to 10
knots during the late morning and afternoon. Nearshore winds may
become more southwesterly during the afternoon as the sea breeze
develops. Seas over the open waters will generally be around 2 to 3
feet during the stronger nighttime flow and closer to 2 feet or less
during the day, with considerably lower wave heights across the
tidal lakes and protected waters. Isolated thunderstorms will remain
possible, particularly during the overnight and early morning hours
over the coastal waters and nearer the coast during the afternoon.
Locally higher winds and seas along with frequent lightning will be
possible near any thunderstorm.

MEFFER
&&

.LIX WATCHES/WARNINGS/ADVISORIES...
LA...Extreme Heat Warning until 8 PM CDT this evening for LAZ034>037-
     039-046>048-056>058-064-070-071-076>087-089>100.

     Heat Advisory from 11 AM to 8 PM CDT Tuesday for LAZ034>037-039-
     046>048-056-070-071-090-091-093>097.

     Extreme Heat Warning from 11 AM to 8 PM CDT Tuesday for LAZ057-
     058-064-076>087-089-092-098>100.

GM...None.
MS...Extreme Heat Warning until 8 PM CDT this evening for MSZ068>071-
     077-083>088.

     Heat Advisory from 11 AM to 8 PM CDT Tuesday for MSZ068>071-077.

     Extreme Heat Warning from 11 AM to 8 PM CDT Tuesday for
     MSZ083>088.

GM...None.
&&

$$

SHORT TERM...ME
LONG TERM....ME
AVIATION...ME
MARINE...ME