Area Forecast Discussion
Issued by NWS New Orleans/Baton Rouge, LA
Issued by NWS New Orleans/Baton Rouge, LA
891 FXUS64 KLIX 171132 AFDLIX Area Forecast Discussion National Weather Service New Orleans LA 632 AM CDT Fri Oct 17 2025 ...New AVIATION... .SHORT TERM... (Today through Saturday) Issued at 627 AM CDT Fri Oct 17 2025 Upper ridging centered from southeast Louisiana to Lake Superior during the evening, with an upper trough from Montana to southern California. At the surface, the axis of high pressure was from Lake Huron to near Mobile. Regional upper air soundings during the evening continued to show precipitable water values near the 25th percentile (about 0.9 inches). This is reflected in the lack of any significant cloud cover over land until near the Ohio River. High temperatures Thursday afternoon were mostly in the upper 80s, although Bogalusa did reach 91. The upper ridge will continue to move eastward to the Appalachians by Saturday afternoon. The trough currently over the Rockies will be over the Plains States by Saturday afternoon, with a shortwave moving through the base of the trough over Oklahoma. As the surface high continues to move eastward, low level wind flow will become more southerly today, returning moisture to the area. Moisture levels still won`t be much more than near the 50th percentile today, and even Saturday morning, but will climb to near the 75th percentile (1.5 inches) by midday, and could be above the 90th percentile (1.8 inches) by sunset. Shear and instability will be increasing, but lapse rates will be rather weak (generally <6 C/km). May start to see some isolated convection by Saturday afternoon, but the main concern for convection will hold off until after sunset Saturday. Highs will again be in the 85 to 90 range for most of the area this afternoon, although the Mississippi coastal counties could be a few degrees cooler with the winds more fully coming off of cooler coastal waters (water temps 78-82F). Highs Saturday should be a couple degrees lower, in the mid 80s, due to cloud cover. Fog could again be an issue toward sunrise, but not confident enough to justify any advisories or significant mentions. If it does occur, it should burn off by about 9 AM CDT. && .LONG TERM... (Saturday night through Thursday) Issued at 627 AM CDT Fri Oct 17 2025 The shortwave and upper trough to our west Saturday afternoon will move across the lower Mississippi River Valley overnight Saturday night. The associated cold front will move across the area late Saturday night into Sunday morning. Moisture levels are forecast to be near the 90th percentile (1.8 to 2 inches), about 40 knots of shear over northern portions of the area, CAPE values around 1000 J/kg, mid level lapse rates around 6.5 C/km, and 0-1km SRH of 150 to 200. That`s certainly enough to monitor the risk for severe weather, with a Marginal Risk of severe weather in SPC`s outlook for Saturday night. Precipitation will be over by midday Sunday, and could be over by sunrise. A northern stream shortwave moving toward the East Coast trough axis is expected to push a reinforcing cold front through the area on Tuesday, but moisture will be extremely limited, and the front could move through completely dry. Not much on tap for Wednesday and Thursday as shortwave ridging moves across the area. High temperatures Sunday will be dependent on how quickly the cloud cover gets out of the way. If the clouds depart early, prior to noon, mid and upper 80s aren`t out of the question, especially if winds turn northerly over the Pearl River Basin. The 12z Thursday medium range temperature forecasts from the ECMWF and GFS were in significant disagreement, especially on overnight lows. Even within the ECMWF ensemble, there was quite a spread on lows. The most recent NBM numbers are pretty much a compromise between the operational ECMWF and GFS temperature forecasts. Hopefully, the significant differences between the ECMWF and GFS resolve somewhat. && .AVIATION... (12Z TAFS) Issued at 627 AM CDT Fri Oct 17 2025 High level cloud cover over the western portion of the forecast area that is associated with a passing shortwave trough axis has helped to limit fog and low stratus development over a larger area this morning. However, there are pockets of fog and low stratus that have formed and these areas are experiencing IFR and lower conditions. The most impacted terminals include ASD, PQL, and APS in the region. Otherwise, prevailing VFR condition will continue at the remainder of the terminals through the evening hours. Later tonight, conditions look favorable for another round of fog and stratus development as the shortwave trough pulls away and a weak area of increased ridging aloft builds in. The highest probabilities for IFR fog and stratus are at MCB and BTR where boundary layer winds will be just weak enough to allow for greater boundary layer decoupling. HDC will be borderline in terms of winds and have MVFR restrictions forecast. These fog and stratus conditions will take hold between 08z and 10z and should clear by 14z tomorrow as boundary layer winds increase. && .MARINE... Issued at 627 AM CDT Fri Oct 17 2025 High pressure centered over the area will continue to gradually shift to the east and southeast today. Winds will turn more east- southeasterly 10 to 15 knots through the day in response to the departing high. A frontal system is expected to slide through the waters Saturday night and Sunday. Winds may briefly get into the 15 to 20 knot range tonight into Saturday, but currently do not see any prolonged periods with wind speeds of 20 knots. After the front moves through on Sunday, winds will shift to the northwest, but choppy conditions will persist. && .PRELIMINARY POINT TEMPS/POPS... MCB 87 65 84 66 / 0 0 40 70 BTR 88 67 87 68 / 0 0 50 60 ASD 85 67 84 67 / 0 0 30 50 MSY 88 72 87 71 / 0 0 40 50 GPT 84 71 84 70 / 0 0 10 50 PQL 86 66 85 68 / 0 0 10 50 && .LIX WATCHES/WARNINGS/ADVISORIES... LA...None. GM...None. MS...None. GM...None. && $$ SHORT TERM...RW LONG TERM....RW AVIATION...PG MARINE...RW