Marine Weather and Tide Forecast for Erath, LA

DISCUSSION
(Today through Thursday)
Issued at 1210 AM CDT Fri Apr 17 2026

A surface high pressure system over the Atlantic Ocean east of the Florida coast will continue to ridge westward along the northern Gulf coast and into the forecast area through early Saturday. This will keep a warm and muggy air mass in place. Both high and low temperatures will be around 5 degrees above climo norms.

A mainly dry west-southwest wind aloft will be over the forecast area through early Saturday that will help keep a cap in place.

Cooling of the boundary layer at night will help form clouds in the low level moisture under the cap. However, boundary layer winds are expected to stay up enough to create mixing to keep any widespread fog from forming with mainly a low stratus cloud deck. During the daytime, heating will also produce some cloud decks, however the cap will keep any significant shower activity from forming.

On Saturday, the upper level ridge over the Gulf will flatten and weaken as it shifts to the south. Meanwhile, a significant upper level storm system originating from the Pacific Northwest will continue to move eastward and deepen into a sharp upper level trough from the Canadian Prairies to the Southern Plains. As it moves further eastward, this system will help move a surface cold front across the forecast area Saturday evening into the overnight.

Both East Pac and western Gulf moisture will be picked up ahead of the upper level trough and pool ahead of the frontal system. The moistening airmass will help erode the cap and along with frontal lift help initiate showers ahead of the front by late Saturday afternoon. Instability is enough during the late afternoon and early evening hours that a few thunderstorms should mix in with the shower activity.

Not much has changed in the guidance with this system from looking at it yesterday. Anomalously high moisture values are expected by late Saturday afternoon into Saturday night with PWAT values above the 90th percentile of 1.6 inches and near the max moving value of 1.9 inches. Meanwhile, Mean Layer Relative Humidity values are progged to be above 80 percent. Which means any storms that form could be efficient precipitation producers. As the front moves eastward during the overnight, instability will decrease and intensity of the shower activity should also decrease as the activity moves toward Acadiana and the Atchafalaya Basin.

Forecast rainfall amounts will follow that scenario with highest rainfall amounts expected northwest of a Beaumont/Port Arthur to Lafayette line with average rainfall amounts between 0.50 and 1.25 inches. The probability of a "wetting" rain or amounts greater than 0.25 inches is between 50 and 80 percent in that area, and probability of over 1 inch is 30 to 50 percent in that area.

Reasonably highest rainfall amounts or the 90th percentile from the NBM is between 2 and 3 inches, again northwest of a Port Arthur to Lafayette line. These amounts could be reached in localized areas as progs show the mean wind speed decreases and winds become parallel to the theta-e ridge along the front in the evening hours.
Therefore, there is some potential that the stronger convection with high rainfall rates may fall for a length of time over the same locations. Thus, a Marginal Excessive Rainfall Outlook (level 1 out of 4) during the Saturday night time period is outlined for much of southeast Texas, central and southwest Louisiana.

Behind the front, high pressure ridging down from the upper Midwest will bring a continental air mass from the Canadian Prairies into the region with cooler temperatures and drier conditions. Through Monday lows and highs will be some 5 to 10 degrees below climo norms.

Also, as this air mass moves in, gusty northerly winds will develop, especially over the coastal waters. This will bring about the potential for some marine hazards. LREF is showing between a 50 and 70 percent chance of gusts over gale force on Sunday morning, with the NBM showing between a 20 to 30 percent chance during the same time period, with the higher probabilities west of Cameron.
Therefore, a Gale Watch or Warning for frequent gusts over 34 knots will be possible.

Also, on Sunday afternoon, low relative humidity values between 25 and 35 percent and 20 foot northeast winds around 15 mph with some higher gusts may bring about some degree of fire danger, however a lot will depend on how much rain falls on Saturday night.

By mid week, temperatures begin to warm up again. A more active southwest flow will also allow for a chance of showers.

07/Rua

AVIATION
(12Z TAFS)
Issued at 605 AM CDT Fri Apr 17 2026

Patchy fog is causing MVFR conditions along the coast but IFR conditions inland. After sunrise conditions will improve to VFR with winds from the south around 10 knots. Overnight more fog is expected.

MARINE
Issued at 1210 AM CDT Fri Apr 17 2026

Surface high pressure will ridge across the northern Gulf from off the Florida coast through Saturday with low pressure forming over the Plains. This will allow for a persistent modest southerly flow.
A cold front is forecast to move through on Saturday night with strong and gusty northerly winds along with building seas behind it.
There is the potential for frequent gusts over 34 knots and gale force conditions on Sunday morning, especially west of Cameron and a Gale Watch/Warning may be needed.

FIRE WEATHER
Issued at 1210 AM CDT Fri Apr 17 2026

Although fuels remain dry across the region with various degrees of drought continues, persistent southerly flow for into Saturday will bring in low level moisture that will allow for minimum afternoon relative humidity values to range from 40 to 60 percent, this will help keep the fire danger somewhat in check through Saturday. A cold front will move across Saturday night that may bring some portions of the area a wetting rain. Strong northerly winds and low relative humidity values are expected behind the front on Sunday that may bring about a fire danger depending on how much rain falls on Saturday night. The low relative humidity and dry conditions will persist into Monday with some potential fire danger, although winds are expected to be lighter.

LCH WATCHES/WARNINGS/ADVISORIES
LA...None.
TX...None.
GM...None.