Area Forecast Discussion
Issued by NWS New Orleans/Baton Rouge, LA
Issued by NWS New Orleans/Baton Rouge, LA
924 FXUS64 KLIX 101835 AFDLIX Area Forecast Discussion National Weather Service New Orleans LA 135 PM CDT Thu Sep 10 2026 ...New SHORT TERM, LONG TERM, AVIATION, MARINE... .KEY MESSAGES... Updated at 109 PM CDT Thu Sep 10 2026 - Deep tropical moisture moving into the area is causing localized heavy rainfall and flooding across urban parts of the I-10/12 corridor. - This elevated risk for localized heavy rainfall leading to street flooding and overflowing of poor drainage will continue on Friday and into Saturday. && .SHORT TERM... (Now through Sunday night) Issued at 109 PM CDT Thu Sep 10 2026 Deep tropical moisture has pushed back into the local area as indicated by the LIX 1200 UTC sounding which had a 2.42" PWAT value, near the daily maximum for September 10th. This is in association with a weak area of low pressure situated south of Port Fourchon that is slowly encroaching on coastal Louisiana. The enhanced low- level convergence in association with this feature and deep tropical moisture is aiding in the development of small bands of showers and storms that are producing highly efficient rainfall rates (2-3" per hour) and frequent lightning. In addition, these bands are anchoring and training over the same areas which is only exacerbating the locally heavy rainfall threat. Localized areas of the New Orleans metro, coastal MS, and Hammond area have received upwards of 3 to 6 inches of rain over the least 6 hours per radar estimates and a few unofficial gauge locations. This illustrates just how efficient and real the threat for locally heavy rainfall that can cause street flooding and overflowing of poor drainage areas. As this weak area of low pressure rounds the surface high centered over the Carolinas, it will gradually lift northward into southeast Louisiana tonight and into Friday. This will keep the risk for locally heavy rainfall elevated as PWATs remain in excess of 2.3 inches. This will mean the excessive rainfall risk will follow this low inland. The latest CAM guidance seemed to be less enthused about coverage of showers and storms on Friday compared to today, but the environment will still be in place to support locally heavy rainfall if any storm sits in one place too long. The main caveat and reasoning for less coverage would be to do with the surface trough and associated surface convergence weakening though simultaneously there will be height falls associated with a weak shortwave trough dipping into the lower Mississippi River valley that would aid updraft growth so there`s some uncertainty here regarding which factors will prevail with storm coverage. As we move into Saturday, this mid-upper shortwave trough will slow and gradually weaken over the area. This will cause heights to slowly rise. Even though PWATs will still remain elevated (>2"), the confidence in afternoon shower and storm coverage has decreased somewhat compared to what is advertised as "Definite" by NBM guidance. As such, PoPs have been lowered 5-15% in most places, but still advertise 60-75% across much of the area which could be generous still. && .LONG TERM... (Monday through Wednesday night) Issued at 109 PM CDT Thu Sep 10 2026 Ridging over the southeast CONUS will gradually expand and intensify as the weak shortwave trough lifts out on Sunday. Healthy afternoon rain chances will linger though they will gradually lower into early next week as rising heights and strengthening ridging put a stronger cap in place and limit afternoon pop up shower and storm activity. This will also mean high temperatures will creep back toward the mid 90s as we kick off the new work week and heat indices could get closer to 108 degrees in a few places, especially over southeast Louisiana. The resurgence in hotter conditions in mid September doesn`t appear to be long-lived as the ridge retrogrades back toward the west and east coast troughing erodes the eastern periphery of the ridge. This would invite the potential for backdoor or decaying fronts by late next week. && .AVIATION... (18Z TAFS) Issued at 109 PM CDT Thu Sep 10 2026 Scattered to numerous SH/TS continue to spread across the area and all terminals are expected to continue to see intermittent TSRA impacts through 2200 to 0100 UTC. Locally higher winds upwards of 20 to 25 knots, frequent lightning, and short IFR to LIFR conditions will be associated with TSRA. SH/TS activity will gradually wane after sunset and MVFR CIGs to VFR conditions will prevail with light to near calm winds. Additional impacts from TSRA will be possible on Friday, especially just beyond the forecast period so new PROB30s will likely be introduced in subsequent forecast cycles as forecast confidence in timing increases. && .MARINE... Issued at 109 PM CDT Thu Sep 10 2026 Though no reports of waterspouts have been received, the surface vorticity associated with a weak surface low near Port Fourchon and high 0-3km CAPE (>150 j/kg) has been create highly favorable environment for waterspout development off the southeast Louisiana coast. A weak area of low pressure will move through the waters today with light and variable winds of 10 knots or less are expected. As the low shifts to the west on Friday, winds will turn more south- southwesterly at 10 to 15 knots. These conditions will persist into Saturday. High pressure centered over the eastern Gulf and southeastern United States will become more dominant as we move into next week, and this will cause winds to turn more south- southeasterly at 5 to 10 knots from Sunday onward. Seas will generally remain in the 1 to 3 feet range with the highest seas well offshore. Additionally, thunderstorm activity will develop each day, peaking in the early to mid-morning hours, and these storms will produce higher wind gusts, waterspouts, and lightning concerns. && .LIX WATCHES/WARNINGS/ADVISORIES... LA...None. GM...None. MS...None. GM...None. && $$ SHORT TERM...TJS LONG TERM....TJS AVIATION...TJS MARINE...TJS