Marine Weather and Tide Forecast for Jefferson, LA

SHORT TERM
(Now through Saturday)
Issued at 1224 AM CDT Wed May 20 2026

Upper ridging over New England this morning, with a weak upper low stuck underneath it over the Bahamas. The main upper trough extended from Lake Superior to Arizona, but there were shortwaves over Missouri and Texas moving northeast in the southwesterly mid level flow. At midnight, an outflow boundary was over extreme northwest portions of the area to the west of Baton Rouge and McComb, while the true cold front extended from near St. Louis to near Dallas. A weakening band of showers and thunderstorms was just ahead of the outflow boundary. Temperatures around the area at midnight were in the 70s.

The general upper pattern doesn't show a lot of change across our area through the end of the week. We stay in southwesterly flow with impulses moving through that flow at 18 to 24 hour intervals.
Each impulse will have the potential to produce a few hours of showers and thunderstorms. Timing of individual impulses moving through the flow becomes increasingly problematic as we get further out in the forecast. Precipitable water values remain in the 1.7 to 1.9 range, which puts it close to the 90th percentile climatologically. So, any of these thunderstorms could put down a quick inch or two of precipitation. If repeat cells occur in a short period over an urban area, it's going to cause a problem. In the near term, there's not much agreement as to which area gets dumped on. A few areas could get several inches of rain while others get little or nothing. Actually more concerned about the cumulative effect on areas than on short term events. Between now and Saturday afternoon, it won't be a surprise if somewhere near Baton Rouge or McComb gets dumped on more than once, but confidence isn't high enough to pin point an area consistently to justify a flood watch just yet.

Little day to day change in temperatures for the rest of the week. What will determine high and low temperatures is when does the rain occur. Areas that see thunderstorms in the late morning hours will be least likely to reach their forecast highs and lows.

LONG TERM
(Saturday night through Tuesday)
Issued at 1224 AM CDT Wed May 20 2026

The active pattern will persist into the long term period as the active southwesterly flow aloft continues along with the series of impulses leading to more scattered to numerous showers and storms, especially when the diurnal cycle and each impulse match up in terms of timing. Overall, the pattern doesn't appear to change through the period. The higher QPF will reside west of I55 with somewhat lower rainfall amounts over the MS Gulf Coast closer to the upper level ridge that will remain parked over the northeast Gulf or western Atlantic. With PWATS nearing 2.0" at times and several rounds of convection, hydro concerns will continue to remain possible through most of the medium range with poor drainage and urbanized areas most at risk. Otherwise, temperatures will remain mild, but with cloudiness and higher rain chances, temps will be right around average for late May.

AVIATION
(06Z TAFS)
Issued at 1224 AM CDT Wed May 20 2026

VFR/MVFR conditions through the cycle with a couple of opportunities for convective development. First will be overnight for the western half of the area as a decaying line of storms moves closer to those terminals. Additional convective development will be possible this afternoon and evening. If convection moves over a terminal there will be a bit more erratic winds as well as IFR or perhaps lower in the heaviest rainfall.
Otherwise, winds will remain light to moderate from the south.

MARINE
Issued at 1224 AM CDT Wed May 20 2026

A large area of high pressure will remain situated over the western Atlantic through the week and into the weekend. This will maintain light to moderate onshore flow through the time. Winds will bounce around headline criteria with sustained winds right around to slightly below 15 kts, especially closer to the coast and west of the MS River. As for showers and thunderstorms, daily isolated to scattered showers will be possible each day however the bulk of the coverage will remain inland. With any thunderstorms locally hazardous winds and waves can be expected.

Any minor coastal flooding that occurred yesterday should quickly abate and expecting tides to be a little lower each day through the remainder of the week and into the weekend.

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