textproduct: New Orleans/Baton Rouge

KEY MESSAGES

Updated at 1052 PM CST Wed Nov 26 2025 - A substantial cool down Thursday and Friday nights with temperatures in the 30s and 40s. A few places could briefly touch freezing across SW MS, and within the Pearl and Pascagoula River drainage areas.

- Hazardous conditions for small craft through Thursday, possibly through the entire weekend.

- Rain threat increases for the weekend and early next week. The rain could be locally heavy at times.

SHORT TERM

(Tonight through Saturday night) Issued at 1052 PM CST Wed Nov 26 2025

Initially, the area will remain under the influence of deep layer northwest flow through Friday morning on the southwest periphery of a strong longwave trough axis dominating the eastern half of the CONUS. The core of a 925mb thermal trough axis will also be passing through the Lower Mississippi Valley today and tomorrow, and this will keep temperatures a good 10 degrees cooler than average through tomorrow afternoon. Model sounding analysis supports daytime highs only rising into the upper 50s and lower 60s today and tomorrow, and strong radiational cooling tonight will allow overnight lows to fall into the 30s and lower 40s both this morning and again Thursday night. The coldest night will be Thursday night as lows fall into the low to mid 30s to the north of the I-10/12 corridor. Temperatures are highly likely to touch freezing in the Pearl and Pascagoula River drainages, but the duration of the freeze will be short enough to not damage vegetation. As a result, a freeze warning will not be necessary for the drainages Thursday night into Friday morning. Overall, have opted to go with NBM 50th percentile temperatures for the overnight lows given the degree of radiational cooling expected both this morning and again on Friday morning.

Conditions will begin to shift Friday and Saturday as the longwave trough axis and associated thermal trough axis begins to lift out of the region and a more zonal flow regime takes hold. Temperatures will remain cool Friday night into Saturday morning due to the very dry airmass in place, but the overnight lows may occur earlier in the night as high level clouds begin to feed in by daybreak on Saturday. In the low levels, winds will begin to veer to a more easterly and eventually southeasterly direction on Saturday, and temperatures will warm back to more average readings for this time of year with highs in the upper 60s and lower 70s. These southeasterly winds will also allow for a surge of deeper Gulf moisture to quickly feed into the region on Saturday. PWATS will rise from the 25th percentile in the morning to the 75th percentile by late evening. Although a weak shortwave through embedded within the zonal flow will pass through the region on Saturday, moisture in the mid-levels will remain limited enough to keep rainfall at bay. However, a northern stream shortwave trough will merge with the southern stream energy over the Mississippi Valley Saturday night. The combination of increasing omega and PWATS further climbing toward the 90th percentile or around 1.25 inches will support rain development over the region. The highest PoP values will be west of I-55 where the deeper moisture and stronger forcing is expected. Most of the rainfall will be in the form of showers, but a few elevated thunderstorms with bases around 5000 feet or higher could form by late Saturday night as mid-level lapse rates approach 6.0 C/km. The rainfall could also turn locally heavy at times late Saturday night over the western half of the CWA.

LONG TERM

(Sunday through Wednesday night) Issued at 1052 PM CST Wed Nov 26 2025

A very unsettled stretch of weather will impact the forecast area from Sunday through Tuesday as a series of fast moving southern stream vorticity maxima slide through the region. As the initial system impacting the area Saturday night shifts to the east, another weak shortwave and jet streak will slide in from the west on Sunday. At the same time, a frontal boundary will slide further south in response to both the passing shortwave and general airmass density differentials. Ample deep layer forcing in the region will tap into the extremely moist airmass as noted by PWATS over 1.25 inches to produce fairly widespread rainfall. This rainfall will be heavy at times, especially from any elevated thunderstorms embedded within the broader moderate rain shield. Given the high moisture content in place, 1 to 2 inches of rainfall with locally higher amounts approaching 3 inches cannot be ruled from late Saturday night through Sunday evening. This beneficial rain will greatly help the ongoing drought conditions in the region. With the region still experiencing an onshore wind, temperatures will remain near average. However, highs may occur a bit earlier in the day as the frontal boundary slowly sinks southward and pushes offshore by the late afternoon hours.

Once we get past Sunday, the forecast confidence begins to falter as model differences increase on the positioning of the frontal boundary. The GFS stalls the front along the coast while the ECMWF and Canadian models push the front past the coastal waters and into the northern Gulf Sunday night. These differences have resulted in a very large temperature spread of around 20 degrees on average from Sunday night through Monday night. The main trend that has been noticed is that the NBM has been placing more weight toward the EURO/Canadian solution the last couple of runs. Given this trend and the decent agreement between these two models, have opted to lean toward a cooler solution to start off the week that ties in more closely with the NBM 50th percentile for temperatures. This results in overnight lows ranging from the upper 30s in southwest Mississippi to the lower 50s along the Louisiana coast both Sunday and Monday nights. Highs only warm into the 50s for most locations on Monday and Tuesday.

Additionally, another fast moving southern stream vorticity max will slide into the region on Monday. A highly difluent pattern aloft and favorable jet positioning will provide ample lift over a region of enhanced baroclincity in the northern Gulf. The end result will be the development of a potent Gulf low Monday into Tuesday that will bring widespread rainfall to the area. Additional forcing in the mid-levels will occur as southerly flow ahead of the system is isentropically forced over the cooler and more stable airmass to the north of the front, and this will further support widespread rainfall development across the entire forecast area. PWATS are projected to surge to the daily max value of around 1.5 inches over this period, so heavy rainfall will be a concern Monday into Monday night. Fortunately, convection looks to be limited as the lapse rates remain weak in the mid- levels, but an isolated elevated thunderstorm embedded within the broader rain shield cannot be completely ruled out.

All of the model guidance is good agreement that a northern stream system will dive southward on Tuesday and merge with the southern stream energy to produce another longwave trough over the eastern CONUS. As this system develops, a stronger frontal boundary will sweep through the region on Tuesday. Strong dry and cold air advection will take hold and skies will rapidly clear Tuesday afternoon and evening. Wednesday into Wednesday night will see northwesterly flow keep skies mainly clear and temperatures cooler than average as a dry and stable surface high builds in from the northwest.

AVIATION

(06Z TAFS) Issued at 1052 PM CST Wed Nov 26 2025

Gusty north winds of over 12 knots at MSY, HUM, GPT, and NEW will be the primary concern for aviators through the morning hours. These winds will begin to relax in the afternoon as a high pressure system becomes more centered over the region. Otherwise, VFR conditions will be in place at all of the terminals as a very dry and very stable airmass remains in firm control of the area.

MARINE

Issued at 1052 PM CST Wed Nov 26 2025

A cold and dry high pressure system will build over the waters through Friday. As this colder and drier air moves across the warmer waters, stronger winds aloft will transport down to the surface. As a result, an extended period of small craft advisory conditions due to northerly winds of 20 knots or greater and rough seas of over 7 feet will impact the waters through Friday. Winds will relax slightly to between 15 and 20 knots and begin to turn more southeasterly and southerly over the weekend as another low pressure system pushes through the region. A weak front will slide offshore and stall over the northern Gulf early next week. As this occurs, northerly winds will develop. At the same time, a low pressure system will strengthen over the northern Gulf Monday night into Tuesday. This will allow the winds to increase back into small craft advisory range as the low passes through.

PRELIMINARY POINT TEMPS/POPS

MCB 36 59 32 57 / 0 0 0 0 BTR 40 62 36 60 / 0 0 0 0 ASD 36 63 32 60 / 0 0 0 0 MSY 47 62 44 60 / 0 0 0 0 GPT 40 63 35 60 / 0 0 0 0 PQL 36 63 30 60 / 0 0 0 0

LIX WATCHES/WARNINGS/ADVISORIES

LA...None. GM...Small Craft Advisory until noon CST Friday for GMZ530-532-534- 536-538-550-552-555-557-570-572-575-577.

MS...None. GM...Small Craft Advisory until noon CST Friday for GMZ532-534-536- 538-550-552-555-557-570-572-575-577.