Area Forecast Discussion
Issued by NWS New Orleans/Baton Rouge, LA
Issued by NWS New Orleans/Baton Rouge, LA
983 FXUS64 KLIX 290512 AFDLIX Area Forecast Discussion National Weather Service New Orleans LA 1212 AM CDT Fri Aug 29 2025 ...New SHORT TERM, LONG TERM, AVIATION, MARINE... .SHORT TERM... (Today through Saturday) Issued at 1206 AM CDT Fri Aug 29 2025 Upper troughing continued from Quebec Canada to Florida this evening, with ridging along the lee side of the Rockies, virtually unchanged from last night. Shortwave energy over Arkansas was driving convection southeastward across northern Louisiana during the evening hours. At the surface, a boundary had moved about as far south as the Interstate 10-12 corridor, and convection is likely to follow this boundary across roughly the northern half of the area overnight if it doesn`t dissipate. The evening upper air soundings from LIX, LCH and JAN all showed precipitable water values right around 2 inches. Evening dew points were generally in the lower and middle 70s, which wasn`t much different than last night. Little change is expected in the overall pattern through Saturday, with the main issue timing of shortwave energy moving toward the base of the trough. Don`t anticipate any significant drying of the column across the area through Saturday, and the 00z HRRR run actually shows moisture near 2.3 inches Saturday afternoon. We`ll need to monitor the potential for localized hydro problems depending on the track of each complex of storms. Would not at all be surprised to see a decent chunk of the area see 36 hour rain amounts in excess of 2 inches, with a few spots getting considerably more. Fortunately, most of the area has been dry this week and should be able to tolerate a couple inches of rain, but could be some localized issues. Cloud cover and precipitation should hold high temperatures in the 80s both days. && .LONG TERM... (Saturday night through Thursday) Issued at 1206 AM CDT Fri Aug 29 2025 There continues to be quite a difference in the forecast scenario between the operational GFS and ECMWF runs for Sunday into at least Tuesday. This is due to the difference in how far southward the frontal boundary reaches over the next several days. The ECMWF operational runs and a significant majority of ensemble members push the boundary well into the Gulf and produce no more than isolated convection beyond about midday Saturday. The GFS cluster doesn`t really allow the front very far south of the Louisiana coast until Tuesday or Wednesday, which is the difference between a mostly dry forecast (ECMWF) beyond Saturday, and scattered to numerous showers and storms (GFS) each day through Tuesday. Over the past couple of days, there`s been internal consistency within the 2 model families, which doesn`t help in narrowing down a target of opportunity. The current forecast solution is much closer to the GFS depiction. Beyond Tuesday, both solutions are in much better agreement with a mostly dry forecast with the front more significantly clear of the coastline. Of course, with the significant difference in precipitation forecasts, guidance carries relatively different values for temperatures, mainly daytime highs. The GFS operational numbers are anywhere from 3 to 8 degrees cooler than the ECMWF for Sunday through Tuesday. With the GFS family of solutions regarding precipitation carrying the load for the NBM, it`s not a surprise that the temperature solutions take a similar tack with highs in the 80s. If the drier solution eventually becomes preferred, highs would need to get nudged upward in later forecasts. && .AVIATION... (06Z TAFS) Issued at 1206 AM CDT Fri Aug 29 2025 Convection moving across northern terminals at issuance time and will carry TEMPO at most terminals through about 09z with MVFR to IFR conditions where there are direct impacts. Could be some fog, particularly at KMCB with IFR conditions mentioned through 13z. MVFR ceilings will redevelop by mid-morning with scattered convection by late morning, and potentially more widespread coverage during the afternoon hours as another impulse moves toward the base of the trough. Not as confident regarding how much convection lingers beyond sunset. && .MARINE... Issued at 1206 AM CDT Fri Aug 29 2025 Main marine concern during at least the first half of the forecast period will be the threat for thunderstorms that could produce locally higher winds and seas. Forecast confidence is a bit lower by late in the weekend, with an approaching cold front. The current wind forecast would indicate generally offshore flow by late Sunday afternoon for most or all of the waters. If the front makes it well into the Gulf similar to the ECMWF solution by Labor Day, that might increase wind speeds enough to justify Small Craft Exercise Caution headlines by Monday or Tuesday. For now, will hold with the current 10 to 15 knots. && .PRELIMINARY POINT TEMPS/POPS... MCB 80 69 85 69 / 90 60 60 20 BTR 86 72 89 71 / 80 50 70 20 ASD 85 70 87 69 / 70 50 70 30 MSY 90 76 89 76 / 60 50 70 30 GPT 83 71 85 71 / 70 60 70 30 PQL 83 70 86 69 / 70 60 80 40 && .LIX WATCHES/WARNINGS/ADVISORIES... LA...None. GM...None. MS...None. GM...None. && $$ SHORT TERM...RW LONG TERM....RW AVIATION...RW MARINE...RW