textproduct: New Orleans/Baton Rouge

KEY MESSAGES

Updated at 517 AM CDT Sun May 17 2026

- Isolated to scattered afternoon showers and storms will return today, mainly for areas along/west of the I-55 corridor. A few storms may be locally strong and capable of locally heavy rainfall.

- Temperatures are forecast to be near to above normal through the middle of next week.

- Monitoring greater coverage in shower/storm chances late week as a front approaches the local area.

SHORT TERM

(Now through Monday night) Issued at 1153 PM CDT Sat May 16 2026

Starting things off with tonight, rather quiet overall underneath mostly clear skies. The earlier 00Z KLIX sounding illustrates a lot of what we expected today, with a (very) strong subsidence inversion parked right at 850mb from compressional warming/sinking in the low-levels resulting in lower total PW. This will be changing as we go into the next 12-18 hours with a few items to discuss. Taking a step back and looking aloft, we remain in a broad weakness aloft as H5 maps illustrate deepening western US troughing and an amplifying ridging pattern over the east coast. Downstream response ahead of this deepening western US trough will be in the form of strong sfc low genesis and attendant response of downstream low-level jet amplification. That low-level acceleration will be plenty to drag up deep NW Gulf moisture north across the southern MS valley region today, revealing a bit more humid feel to the air today as moisture advection wins over afternoon PBL mixing, with dewpoints well into the 70's areawide (maybe upper 60's east of I-59 closer to the surface high/removed from the moisture tongue setting up to the west). HRRR soundings for Sunday afternoon (specifically for KBTR) illustrate the transition of the airmass in the form of lifting/contracting of the strong low-level subsidence inversion in place thanks to rather impressive WAA/increasing low-level moisture regime. This, in conjunction with surface heating will set the stage aloft to provide ample building instability, and as mentioned yesterday, hail growth cape in the 800-900J/kg range. Additionally, HRRR sfc wind vectors illustrate broad confluent directional SE flow setting up this afternoon across SE LA, and given the potential of a skewed W/NW lake/seabreeze from Lake Pontchartrain/Maurepas, combined with targeted SE/NW oriented confluent cloud bands/cloud streets from Terrebonne, Lafourche and Plaquemines Parishes, convection might get it's spark near any of these complex boundary collisions/interactions. Targeting the most likely area will be generally along/west of I-55 into the Atchafalaya Basin/SW MS and including the river parishes towards the Southshore, near metro NOLA where boundary collisions will supply the necessary forcing to support isolated stronger updrafts for a few localized strong storms. H5 temps -10 to -11C and the aforementioned hail growth cape values will support hail in any locally stronger storm, with gusty winds and dangerous lightning a threat as well. Additionally, free storm motion (away from boundary influence) will be slow today, upwards of 4-6kts which could produce locally torrential rainfall. This will need to be watched, especially where updrafts become rooted to boundary collision points and could become temporarily stationary. Elsewhere, mainly dry east of I-55 away from the deeper low-level moisture. No adjustments were needed for highs today, as verification yesterday, the deterministic NBM and 50th percentile were just about aligned for all locations.

It's generally the same story on Monday with nothing major changing, with isolated to scattered pop-up storms mostly confided to boundary interactions once again, with the same isolated strong storm potential/isolated flash flood depending on how updrafts root themselves/interact with adjacent nearby storm outflow boundaries but chances appear best along/north of I-10/12 but also includes the River Parishes. KLG

LONG TERM

(Tuesday night through Saturday night) Issued at 1153 PM CDT Sat May 16 2026

The long term begins with an active H5 southwesterly flow with many ripples (shortwaves) within the flow to help generate an overall wetter period. Although POPs will be nonzero even during the overnight hours, the best potential is when these vorts/impulses move over the region during peak heating enhancing the likelihood of showers and storms. At the surface, southerly flow will continue to pump rich gulf moisture into the region. PWats range from 1.5-1.8" respectively, which could lead to localized flooding in low spots. Also, with the wider updrafts, DCAPE values and even forecast inverted V suggest strong wind gusts will also be possible.

The pattern will continue through the end of the week and into the upcoming weekend as the active southwest flow aloft remains over the region with continued series of impulses driving higher-end POPs. With the higher POPs afternoon temperatures will likely be held down, but still will have a chance to warm into the lower to middle 80s prior to convective initiation. Nights will be sultry with most locations not cooling below 70s. (Frye)

AVIATION

(12Z TAFS) Issued at 517 AM CDT Sun May 17 2026

Expect primarily VFR flight conditions for most area terminals through the morning hours. Will monitor for SCT TSRA chances primarily 18-23Z this afternoon, with greatest probabilities for KBTR, KMCB, KHDC, KHUM and near KMSY terminals. Any individual passing storm could contain gusty, erratic downdraft winds and reduced CIGs/low VIS due to heavy rain. However, outside of any SCT TSRA activity, expect prevailing VFR with all activity coming to an end around sunset. Seeing additional indications of lower CIGs late Sunday night/early Monday morning, which may be especially true for areas that sees rain later today, but further TAF updates will reflect greater confidence as we near closer. KLG

MARINE

Issued at 1153 PM CDT Sat May 16 2026

High pressure anchored to the east offshore the mid-Atlantic states will continue to provide onshore SE flow today, into next week. Onshore winds west of the MS river delta are expected to steadily increase to around 12-18kts as the pressure gradient tightens, with exercise caution headlines now in effect through Sunday night/Monday morning. Moisture steadily increasing will begin to provide a few scattered shower chances mainly next week, with best chances mainly late-week as a front approaches the northern Gulf coast. Waves/seas will steadily increase early next week given ongoing SE fetch reaching 3-5ft for outer Gulf waters (primarily west of the MS delta) to 2-3ft for nearshore waters, but winds back down some mid/late week reducing wave/seas. KLG

LIX WATCHES/WARNINGS/ADVISORIES

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