Marine Weather and Tide Forecast for Chalmette, LA

SHORT TERM
(This evening through Friday night)
Issued at 1215 PM CST Thu Mar 5 2026

Anomalous warm air aloft in addition to the moisture return flow on the western flank of the surface high is keeping temperatures well above normal for this time of year. Highs will continue to flirt with daily records through Saturday. Moisture return will also bring dew point temperatures close to the 70s along and south of the I- 10/12 corridor which will keep low temperatures elevated to near record warm minimum temperatures.

Onshore flow and anomalous low-level warmth will provide ample moisture and instability for weak convection to develop each afternoon, focused predominantly along areas of focused confluence where the return flow rounds the high pressure. Today, that focus will be comparable to yesterday where some showers and storms will try to develop along and west of the I-55 corridor. However, coverage appears to be more suppressed today than yesterday with less confluence to focus lift and vertical growth of updrafts. Much of the same can be expected tomorrow though coverage may expand farther eastward into southern MS as the western flank of the surface high erodes.

Elevated winds and cloud cover will limit fog development to more strictly advective in nature. The warm, unstable conditions with ample daytime mixing away from the apex of the surface high do not lend confidence to strong capping inversions that would promote dense fog development. As such, fog development will be limited to the colder shelf waters and adjacent coastal areas where the onshore flow carries the fog toward. REFS/HRRR probabilities indicate the highest likelihood (50-70%) of any dense fog developing tonight will be in the Mississippi Sound, Lake Borgne, northern Lake Pontchartrain and the adjacent northshore and coastal Mississippi areas inland. Confidence is medium in fog development, but it is low in how dense this fog will be as it will likely be induced by low stratus build down to a degree and be more patchy in nature.
Further monitoring of this will be needed into the evening hours to determine if dense fog products will be necessary.

LONG TERM
(Saturday through Wednesday night)
Issued at 1215 PM CST Thu Mar 5 2026

A large-scale western US trough will be "squeezed" between building ridges over the Pacific NW and the SE CONUS. This will pinch off the base of the highly positively-tilted trough into the SW CONUS. This pattern suggests what would eventually be the detachment of the lead energy/base of the shortwave going across the northern/central Plains into the Midwest, supporting widespread severe weather while the lingering energy is left behind to meander over Baja as the US transitions into a quasi- zonal pattern. As the best energy/lift advances into the northeastern US, we'll see a weakening front drift our way and slow with time as it becomes parallel to low/mid-level flow reducing it's forward momentum. Late Saturday, what is left from the earlier day's severe weather over the south/central US will surge east into the ArkLaTex to eventual MS valley region. The primary caveat to severe weather arriving into our area will be that these storms will be losing the greatest dynamic lift/support and losing daytime heating/supportive thermodynamics. It's cautioned, that the extent/scale of upstream convection in this region during the afternoon/evening could potentially create a cold pool, at a scale that could self-sustain lift and continue this activity east and even southeast nearing our area Saturday night/Sunday morning. Lots of "what if's" with this possible scenario and will likely fully depend on the upstream depth/extent of severe convection and if it could counteract the aforementioned lack of environmental support. Late- hour RRFS runs are beginning to hint at this potential, so something to keep an eye out on.

Beyond this going into Sunday to eventually early next week, we enter a slight break in subtle NW Gulf ridging ahead of the upper- level low stationed over NW MX, but it won't take long until this energy slides east into the southern US, positioning the SE US into a favorable synoptic setup for severe weather. Many things to watch including how deep this upper-low can maintain, the depth/extent of the kicker shortwave that tries to pick it up over the northern US and eventual position of the low itself which will reveal which area(s) may be more pinpointed in the risk for severe weather. Many things need to come together just right, so for now, will continue to message the potential for the risk around mid-week, but stay tuned to the forecast as we near closer.

AVIATION
(00Z TAFS)
Issued at 440 PM CST Thu Mar 5 2026

VFR to MVFR conditions prevail at all area airports. Conditions will drop to MVFR to IFR at all area airports for a few hours around daybreak due to lower ceilings and visibilities from fog conditions. These conditions will continue through mid-morning.
MSW

MARINE
Issued at 1215 PM CST Thu Mar 5 2026

Onshore southeasterly flow will persist today through the rest of the week and weekend averaging generally 8-12kts with gusts 12-15kts at times. Conditions will remain favorable for areas of coastal fog for nearshore waters each morning, mainly from 10PM-10AM. Otherwise, daily isolated to scattered shower/storm chances will persist each day closer to nearshore areas, with rain chances increasing more as we get into the weekend. Onshore southeasterly flow is expected to persist through atleast the middle of next week.

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