Marine Weather and Tide Forecast for Belle Chasse, LA

UPDATE
Issued at 523 AM CDT Mon May 18 2026

Have trimmed back PoPs for today somewhat, as NBM numbers are coming a bit more in line with MAV/MET. While thunderstorm development can't be entirely precluded anywhere in the CWA today, the Baton Rouge area and points to the west have greater potential than anywhere else in our area.

SHORT TERM
(Now through Thursday)
Issued at 1213 AM CDT Mon May 18 2026

Upper ridging across much of the eastern half of the country tonight, with troughing over the Intermountain West. This is producing southwesterly upper flow just to our west. At the surface, a Bermuda High pattern extends west along the northern Gulf Coast. Frontal boundaries were over the Plains States.
Temperatures and dew points were generally in the 70s during the late evening hours.

With high pressure centered off the east coast, southeast winds will continue to bring moisture back into the area. A confluent zone between the high to our east and low pressure taking shape near the Four Corners is currently manifesting as a broad area of clouds stretching from southern Texas through the middle Mississippi Valley. The airmass remains rather moist with precipitable water values in the 1.6 to 1.8 range, in the neighborhood of the 90th percentile climatologically.

Today and Tuesday will see similar conditions as we had on Sunday, although moisture may be a touch less, but not enough to make much difference in the soundings. The highest rain chances will generally across northwestern areas and an isolated threat of stronger storms producing gusty winds and heavy rainfall. To be honest, current forecast PoPs for both days look a bit on the high side, at least 10 percent or so today, but that isn't a big enough change to chase. Will see how today plays out, but the expectation is that rain chances tomorrow will probably need lowered across the western half of the forecast area later today.

Shortwave energy Wednesday and Thursday will be much closer to the area and suppressing the ridge somewhat, so higher precipitation chances are entirely reasonable, but 80 percent at BTR seems a little high for this pattern, by probably 20 percent.
Will hold for now, as neighbors grids haven't departed from NBM either.

Little day to day change in temperature trends. One could probably get away with using persistence rather than guidance through much of the workweek. Cloud cover and timing of precipitation development would be the main factors in any departure from guidance, and those will change from day to day.

LONG TERM
(Thursday night through Sunday)
Issued at 1213 AM CDT Mon May 18 2026

The active southwesterly flow aloft will remain in place as the H5 ridge continues to reside over the northeast Gulf. Within the flow there will continue to be a series of upper level impulses that will help generate shower and thunderstorm activity, especially during the afternoon hours. The best potential for rainfall will be across the western half of the CWFA away from a bit stronger upper level subsidence in closer proximity to the ridge axis to our east. That said, there will be at least modest POPs for coastal MS. At this juncture, there will be a conditional severe threat...mostly associated with strong gusty winds. Additionally, the continued waves of showers and storms will also help produce at least a localized flooding threat, especially for the BTR area where there could be several days with afternoon convection. PWats are a also somewhat favorable with 1.5-1.8" with the higher values over the western portions of the CWFA. Again, this pattern pretty much locks in and remains in place throughout the long term period. With the increase in cloudiness and rain chances, temperatures will be a bit lower, but still around climo. (Frye)

AVIATION
(12Z TAFS)
Issued at 523 AM CDT Mon May 18 2026

Somewhat surprisingly, haven't really seen much in the way of low clouds this morning. Have seen a little development near KMCB in the last hour, but everyone else is VFR at this point. Do expect at least some MVFR ceilings to develop by mid-morning as cumulus field develops. Some potential for TSRA development this afternoon, but the only terminal the threat is high enough to mention is at KBTR, where PROB30 will be in place for late afternoon. Threat will be a little higher tomorrow afternoon. Also will have a threat of low ceilings/visibilities toward sunrise tomorrow, especially at KMCB (IFR or lower).

MARINE
Issued at 1213 AM CDT Mon May 18 2026

Onshore flow will persist as high pressure remains anchored over the western Atlantic. A tightening pressure gradient between this high and low pressure across the plains states will lead to strengthening winds, especially west of the Mississippi River.
Exercise Caution headlines will remain in effect through the overnight hours. As moisture increases across the region, he chance of daily showers and storms will gradually increase, with the best chances later in the week as a weak front approaches the area. Some storms will be capable of producing locally hazardous winds and waves.

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