FXUS64 KLCH 190543 AFDLCH Area Forecast Discussion National Weather Service Lake Charles LA 1243 AM CDT Tue May 19 2026 ...New DISCUSSION, AVIATION, MARINE, FIRE WEATHER... .KEY MESSAGES... - An unsettled pattern will be in place from late Tuesday into the weekend as the southern jet stream brings a series of upper level disturbances to work with a very moist air mass. - The showers and thunderstorms that develop will have the potential to produce high rain rates and there is a risk of heavy rainfall and a risk for flooding into early next week. - Temperatures will remain on the warm and humid side. && .DISCUSSION... (Today through Monday) Issued at 1240 AM CDT Tue May 19 2026 With a low pressure system along a frontal boundary over the Southern Plains, gradient is expected to stay up enough for southeast winds to bring in low level Gulf moisture. This will allow for low clouds to form under the cap and make for a muggy night. During Tuesday, a cap around 70H is expected to hang around that will help suppress convection for the most part with just some hit or miss type storms during the afternoon. Hot and muggy conditions will continue on Tuesday. The first question in the forecast is for Tuesday evening into Tuesday night. Frontal boundary over the Southern Plains will continue to sag southeast and initiate showers and thunderstorms over north central and northeast Texas on Tuesday afternoon. Just how strong this activity gets and the strength of any convective outflow boundary will tell if the forecast area receives any shower activity during the evening into the overnight hours. Some of the CAMs indicate a MCS forming that will be able to make it into the northwest portion of the forecast area before weakening. Therefore, a marginal risk of both severe weather (mainly winds) and excessive rainfall will be outlined to account for this. A shift to a more active pattern will come by Wednesday that looks to last through this week and even into next week bringing high chances for rain and above climo norm precipitation amounts. Generally an upper level trough will be found across the Western US into the Rockies with an upper level ridge over the eastern Gulf and northwest Caribbean. In between the sub-tropical jet will stream over the forecast area bringing mid and upper level moisture from the Tropical Pacific to go along with the low level Gulf moisture. This will allow the forecast area to see a highly anomalous moist air mass with daily PWAT values over the 90th percentile of 1.79 inches and near the Max Moving Average of 2+ inches. Meanwhile, mean layer relative humidity between 100H-50H will be over 80 percent. Warm cloud precipitation processes will also be noted as the warm cloud layer is projected to be from 11k to 15k feet, noting an almost tropical like air mass. So, we do know that there will be several days of high rain chances with possible locally heavy rainfall and a flood risk. WPC has outlined a majority of the forecast area in a Marginal (1 out of 4) or at least a 5 percent chance of excessive rainfall leading to flooding for each day through Friday, and extended WPC hazards keep a risk of heavy rainfall with flooding possible all the way through May 27. What is of a lower confidence is the timing each day of when the precipitation will be the most widespread and at its heaviest. It will not rain all the time, but the timing of each upper level disturbance and if it comes during max daytime heating, will be the story of when the rain chances will be the highest. So each day will be more fine tuned the closer in time we get to each day. Otherwise, temperatures will remain rather warm with humid conditions through the period. 07/Rua && .AVIATION... (06Z TAFS) Issued at 1240 AM CDT Tue May 19 2026 With low pressure over the Southern Plains, southerly boundary layer winds will stay up enough during the overnight that fog is not expected with MVFR ceilings developing below the cap. Breezy southerly winds will again occur after sunrise on Tuesday with ceilings gradually lifting to VFR after 19/18z. The cap is expected to hold enough that convection is expected to be very spotty during the afternoon. There is the possibility of a complex of thunderstorms to move into the forecast area after 20/00z, however there is not enough confidence to mention anything other than vicinity convection to account for it. 07/Rua && .MARINE... Issued at 1240 AM CDT Tue May 19 2026 Breezy onshore winds will decrease some by morning with light to moderate southeast flow and light to modest seas then expected to persist through the week. Chances for showers and thunderstorms will increase by Wednesday and remain high through the week into the weekend as a stalled frontal boundary and a series of upper level disturbances produce several waves of precipitation. && .FIRE WEATHER... Issued at 1240 AM CDT Tue May 19 2026 Expect modest southerly winds to continue through the next several days bringing in rich amounts of Gulf moisture. Afternoon Minimum RH values will be above 60 percent through the week. High chances for daily showers and thunderstorms are expected through the week into early next week as a stalled frontal boundary and a series of upper level disturbances provide waves of precipitation each day. Some locally heavy rainfall will be possible. && .LCH WATCHES/WARNINGS/ADVISORIES... LA...None. TX...None. GM...Small Craft Advisory until 4 AM CDT early this morning for GMZ450-452-470-472. && $$ PUBLIC/FIRE/MARINE...07 AVIATION...07