textproduct: New Orleans/Baton Rouge

KEY MESSAGES

Updated at 1241 PM CDT Thu May 21 2026

- Expect high rain chances through the next several days. 7 day rainfall totals will range from 4 to 7 inches in the northwest to less than an inch of much of coastal MS and extreme SELA.

SHORT TERM

(Now through Sunday night) Issued at 1241 PM CDT Thu May 21 2026

The upper level pattern hasn't changed much lately. A cutoff low is located over the western Atlantic east of Florida while broad scale troughing encompasses nearly the entire CONUS except the southeastern portion of the country. Both low level southeast flow and mid level southwest flow continue to transport deep layer moisture into the local region. Evidence of this is clearly shown on the 12Z KLIX sounding, which had a PW of 2.07 inches (only 0.06 inches below the daily record value). This highlights just how moist and summer-like the airmass has become across the forecast area. Model soundings show little change through the afternoon and evening hours, with PW values generally remaining between 2.0 and 2.2 inches.

Mid level lapse rates and deep layer shear remain too weak to support an organized severe weather threat. However, storms will still be capable of producing very heavy rainfall rates given the deep moisture profile and warm cloud depths in place. Localized hourly rainfall rates of 2 to 4 inches per hour will be possible within the strongest cores this afternoon and evening. The weak steering flow regime, combined with Corfidi vectors generally below 20 knots, may allow for slow moving or occasionally backbuilding convection, especially near boundary interactions. This raises concern for localized training of storms and isolated flash flooding, particularly in urban and poor drainage areas.

Going into the overnight period, confidence remains lower regarding the evolution of any additional convective rounds tied to subtle impulses moving through the broad trough. CAM guidance remains split between sparse overnight showers versus another organized cluster of storms capable of producing a localized flash flooding threat.

Generally speaking, Friday looks like a similar pattern with another round of scattered to numerous showers and thunderstorms capable of producing torrential rainfall and localized flooding impacts. Warm and humid conditions combined with considerable cloud cover should continue to limit overnight cooling. It will certainly feel like early summer as lows struggle to fall below the lower to middle 70s. A quick look at record warm low temperatures shows forecast lows may approach records at several locations across the CWA.

MEFFER

LONG TERM

(Monday through Wednesday night) Issued at 1241 PM CDT Thu May 21 2026

An unsettled and moisture rich pattern will persist through much of the extended forecast period as broad ridging remains suppressed to the south and east while weak troughing lingers across the entire region. Daily rounds of predominately (but not definite) diurnally driven showers and thunderstorms are expected each afternoon through the weekend and into\ early next week.

Precipitable water values generally between 1.8 and 2.2 inches will continue to support efficient warm rain processes and locally heavy rainfall with any thunderstorms that develop. Rainfall coverage may fluctuate somewhat day to day depending on subtle mesoscale boundaries, convective overturning from prior day activity, and shortwaves passing through the base of the broad scale trough... but overall confidence remains high in continued high daily POPs. High temperatures will remain near climatological normals but lows above normal due to increased cloud cover and precipitation coverage.

Although widespread flooding is not anticipated at this time, isolated nuisance flooding and localized flash flooding issues will remain possible each day, especially in urban areas and locations that receive repeated rounds of convection.

MEFFER

AVIATION

(18Z TAFS) Issued at 1241 PM CDT Thu May 21 2026

Showers and storms have been impacting terminals off/on all morning long. Threat of TSRA may wane some this afternoon and evening but potential exists for new development during the overnight period. Main impacts will be torrential rainfall which lower visibilities and lightning strikes. Will handle that potential with TEMPO and PROB30 groups.

MARINE

Issued at 1241 PM CDT Thu May 21 2026

Persistent onshore flow of 10 to 15 knots will remain in place through this with high pressure generally centered east of the local coastal waters. Seas will remain well below any hazardous limits at 1 to 3 feet through this period. As we move into the back half of the week, we will see a weak cold front drift south towards the coast and stall along the northern Gulf Coast. That'll lead to both weaker winds overall as well as north or south winds depending on coastal zone's location in related to the boundary. A stronger upper level trough moves through the region Saturday morning. Expect to see at least Exercise Caution, possibly low in Small Craft Advisory, conditions behind this front.

MEFFER

LIX WATCHES/WARNINGS/ADVISORIES

LA...None. GM...None. MS...None. GM...None.