textproduct: New Orleans/Baton Rouge

SHORT TERM

(Tonight through Sunday night) Issued at 1112 PM CDT Thu Jul 10 2025

Little change in thinking from the previous forecast package in terms of the overall pattern across the central Gulf coast through the weekend. A weak upper level trough axis that has been over the region the last several days has started to slowly dissipate tonight and will continue to do so through the day on Friday. As this occurs, a broad upper level ridge centered over Florida and eastern Gulf will expand westward and eventually become directly centered over the region on Sunday. Increasing upper level subsidence will both warm and dry the mid to upper levels of the atmosphere, and this will effectively induce a decent mid- level capping inversion around 700mb. This inversion will help to limit updraft growth, except where low level forcing mechanisms like the seabreeze boundary and any outflow boundaries from previous thunderstorm activity are in place. As a result, cloud development and overall convective coverage will be lower than observed the past few days. This is reflected in the PoP forecast which drops from 50 to 60 percent on Friday down to 30 to 50 percent for Saturday and Sunday. The highest PoP is in coastal areas where seabreeze interactions will allow for more convective development as noted previously. Model sounding analysis continues to show favorable conditions for some wet microbursts to occur on Saturday and Sunday with the deepest updrafts that develop. DCAPE is forecast to be around 1200 J/KG and dry air entrainment into these stronger updrafts is highly probable each day. The end result is that a few strong to severe wind events could occur both Saturday and Sunday afternoon.

Temperatures will also warm due to the combination of subsidence aloft, greater solar insolation, and slightly lower humidity as the dry air aloft mixes into the boundary layer. Highs will climb from the upper 80s and lower 90s today into the lower to middle 90s for Saturday and Sunday. Heat index values values will also increase as temperatures warm, but should remain below heat advisory limits both on Friday and Saturday. By Sunday, heat indices will begin to exceed advisory levels with values generally between 108 and 110 degrees. A heat advisory will most likely be needed for Sunday over non-coastal portions of the forecast area.

LONG TERM

(Monday through Thursday night) Issued at 1112 PM CDT Thu Jul 10 2025

The upper level ridge and resultant deep layer subsidence will remain the dominant feature across the area through Wednesday. This will keep warmer than average temperatures, dangerous heat index values of 108 to 112, and lower rain chances in place through the middle of next week. Heat advisories will likely be needed each day through Wednesday as temperatures climb into the middle to upper 90s beneath the dome of high pressure. The strong mid-level capping inversion still in placed will limit most convection to coastal locations where the seabreeze will continue to serve as a low level forcing mechanism. Additionally, the wet microburst potential will also remain elevated each afternoon as DCAPE values remain above 1000 J/KG. This will keep the low end severe risk of some isolated damaging wind gust events in place each day through Wednesday.

All of the model guidance is in good agreement that the upper level ridge will begin to shift further to the west by Thursday. At the same time, a broad inverted trough will approach from the east. This approaching trough will do two things, increase our moisture aloft and provide increased lift. The combination of PWATS returning back to more seasonal averages for this time of year and greater deep layer forcing will support more convective activity during peak heating hours on Thursday. PoP values reflect this by increasing back into the 40 to 50 percent range, or pretty much the normal PoP for mid-July. The greatest convective activity will still be confined to the coast as the influence of the ridge will not be completely gone on Thursday, but this convective activity will help to lower temperatures back to near average in the upper 80s and lower 90s for coastal locations. Further inland, temperatures should warm back into the mid 90s before any thunderstorm activity forms in the mid to late afternoon hours on outflow boundaries from the coastal convection. As a result, heat index values should be supportive of one more day of heat advisories for our inland locations.

AVIATION

(06Z TAFS) Issued at 1233 AM CDT Fri Jul 11 2025

A pocket of a IFR to LIFR stratus has formed over rain-saturated areas along and east of the Mississippi River between Baton Rouge and McComb. TEMPOs have been added to account for SCT to BKN stratus to intermittently affect BTR, HDC, and MCB through the overnight hours as surface winds remain too weak to move this out of the area. Cannot rule out some of this stratus spreading eastward toward the Pearl River Basin such as BXA and ASD prior to sunrise. Low stratus and MVFR fog will gradually clear out after sunrise at these terminals. Thunderstorm activity will be most likely between 17z and 23z, and this threat is reflected by PROB30 wording in the forecast at all of the terminals. If a storm directly impacts a terminal, brief downpours will produce a period of reduced visibilities, gusty winds, and lightning. Any convective impacts should generally be 30 minutes or less.

MARINE

Issued at 1112 PM CDT Thu Jul 10 2025

Marine conditions will be benign through the period outside of any localized impacts from convection. In response to a broad ridge over the Gulf, winds will generally be out of the south/southwest at 10 kts or less aside from areas near the immediate coastline where sea/lake/land breeze cycles will have an influence on both direction and speed. Otherwise, a fairly typical summertime convective pattern will persist with showers and storms developing during the late night, peaking during the morning hours, and diminishing through the afternoon and evening.

PRELIMINARY POINT TEMPS/POPS

MCB 72 93 72 94 / 10 40 20 30 BTR 74 94 75 93 / 10 50 30 50 ASD 74 93 73 93 / 10 40 20 40 MSY 78 94 78 93 / 10 40 30 50 GPT 76 91 76 92 / 20 40 20 40 PQL 74 92 73 93 / 20 40 20 30

LIX WATCHES/WARNINGS/ADVISORIES

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