Area Forecast Discussion

KEY MESSAGES

- A few sprinkles of rain may occur over southeast Texas through Monday evening. Otherwise, cool and dry air will remain in place through Tuesday morning before light east winds turn more southeasterly

- Rain chances increase Tuesday into Wednesday as a surge of moisture moves up the TX coast. A Marginal Risk for Excessive Rainfall is in place on Wednesday

- Warmer temperatures, humid conditions, and isolated shower activity can be expected through the later half of the period

DISCUSSION

(This evening through next Sunday) Issued at 226 PM CDT Mon Apr 20 2026

Surface high pressure currently dominates the picture across much of the eastern CONUS, with ridging generally extending from the Great Lakes into the Deep South. The resulting northeasterly to easterly flow is quite dry, with resulting PWAT values ranging from 0.3 inches across central LA to 0.7 inches over southeast TX. The 18Z KLCH sounding reported a PWAT of 0.40 inches, which is below 10th percentile and approaching daily minima per SPC sounding climatology. A weak upper level disturbance is entering our southeast Texas counties today, bringing widespread cloud cover and a few light showers to these areas. With the aforementioned dry airmass in place, not much of this is expected to reach the ground, but a few sprinkles can't be ruled out. Introduced some low end pops to southeast TX for this afternoon and early evening to account for this possibility, but would not anticipate any measurable rainfall from these. Afternoon highs should be in the mid to upper 70s area- wide.

Heading into Tuesday, a low pressure area will develop over south Texas which will turn flow more to the southeast. As a result, rain chances will increase over much of the region Tuesday into Wednesday as a few upper level disturbances track through the area. Moisture will be anomalously high, with PWAT values approaching 1.5 inches (90th percentile) west of I-49. Accordingly, the Weather Prediction Center maintains a Marginal Risk (level 1/4) of excessive rainfall for southeast TX and most of southwest LA Wednesday where this greatest moisture will be located. However, it is worth noting that instability does not look too impressive due to continued surface ridging and what will likely be extensive cloud cover over the region, which may act to limit the heavy rainfall threat and keep any thunderstorm chances relatively low.

The surface ridging will shift off to the east after midweek, keeping a moist southerly flow in place over the area as a few more upper disturbances push eastward across the CONUS. This should keep a threat for isolated to scattered convection going each afternoon heading into the weekend. This pattern will keep temperatures on a warming trend, with afternoon highs reaching the mid 80s by the weekend.

64/Silas

AVIATION

(00Z TAFS) Issued at 656 PM CDT Mon Apr 20 2026

Radar shows showers continuing to inch closer to our SETX terminals; however, very little rain is falling. We could see some light showers tonight but this was omitted from the TAFs. Another round of showers is expected to move into SETX tomorrow morning, and spread across the rest of the area through the afternoon to evening hours.

MARINE

Issued at 226 PM CDT Mon Apr 20 2026

Elevated easterly winds around 15-20 kt will be expected through this afternoon, then gradually diminish to 10-15 kt overnight tonight. A developing disturbance over south Texas will cause flow to begin acquiring an onshore component as well as increase rain chances over the area through midweek. As this disturbance weakens after Wednesday, southerly winds around 10-15 kt will be expected through the end of the week and into the weekend, along with isolated to scattered showers and thunderstorms each afternoon.

FIRE WEATHER

Issued at 226 PM CDT Mon Apr 20 2026

A dry continental airmass currently sits over the CWA, with afternoon minimum RH values expected around 25 to 40 percent. However, not much in the way of fire weather concerns is expected with light easterly winds around 5-10 kt. Winds will begin shifting to the southeast by Tuesday, which will bring Gulf moisture into the area and increase rain chances. Anomalous moisture and elevated rain chances should persist through the end of the week and limit any fire weather concerns.

LCH WATCHES / WARNINGS / ADVISORIES

LA...None. TX...None. GM...None.