Area Forecast Discussion
Issued by NWS New Orleans/Baton Rouge, LA
Issued by NWS New Orleans/Baton Rouge, LA
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580 FXUS64 KLIX 020223 AFDLIX Area Forecast Discussion National Weather Service New Orleans LA 923 PM CDT Wed May 1 2024 ...New UPDATE... .UPDATE... Issued at 914 PM CDT Wed May 1 2024 Monitoring a small cluster of showers or thunderstorms southeast of Baton Rouge over the last 30 minutes. Seeing radar returns as high as 30,000 feet, so we can`t rule out a little lightning with it, but certainly not anticipating severe weather. May be a weak boundary out there as there was about a 10 degree F difference in dew points between Baton Rouge and Gonzales at 8 PM CDT. Expect that it should rain itself out in the next 30-60 minutes as wind fields continute to weaken. Due to the extremely limited areal coverage, not currently planning on a forecast update unless areal coverage of precipitation increases. Secondary concern will be for fog development again tonight. Would note that NBM probabilities for visibilities less than a mile are running about 10-15 percent lower than the same time last night. Not enough confidence for an advisory at this time. && .SHORT TERM... (This evening through Thursday night) Issued at 211 PM CDT Wed May 1 2024 A fairly strong mid to upper level shortwave ridge axis continues to dominate the Gulf South today and this will continue into the overnight hours. Beneath this mid to upper level ridge, southeast flow off the Gulf of Mexico will continue. This onshore flow regime will continue to pump Gulf moisture into the low levels, and dewpoints will remain elevated in the 60s. This will also limit overnight cooling with lows only falling into the upper 60s and lower 70s tonight. These values are 5 degrees warmer than average. Although conditions do not look as favorable for fog development tonight due to stronger boundary layer winds of around 15 knots and increasing cirrus coverage from storms over Texas, some patchy fog development could occur right around daybreak over inland areas. Tomorrow will see a fast moving shortwave trough axis push in from Texas. The majority of the forcing with this system will be shunted to the north of the CWA due to the strength of the ridge axis aloft, but weakening band of showers and thunderstorms could push into the northwest third of the CWA tomorrow afternoon. Have bumped PoP values to 50 to 60 percent for areas to the north and west of Baton Rouge where the combination of higher upper level omega and enough cooling aloft to weaken the strong mid-level cap should be in place to support updraft development. Away from this region, the influence of the ridge and resultant subsidence will be strong enough to keep the mid-level cap in place. This is evident by weak mid-level lapse rates of around 5.5-5.7 C/km tomorrow afternoon across coastal Louisiana and coastal Mississippi. Fortunately, for the areas that could see some convective activity tomorrow afternoon, shear values will remain weak, and severe storms are not expected. By tomorrow evening, the convective threat will diminish as the shortwave trough pulls to the northeast and a brief period of increased ridging and negative vorticity takes hold of the northwest third of the CWA. Temperatures will be closer to average tomorrow into tomorrow night as increased cloud cover reduces overall solar insolation. && .LONG TERM... (Friday through Tuesday night) Issued at 211 PM CDT Wed May 1 2024 Another shortwave trough will quickly move through the region on Friday, and this trough is expected to impact the area more effectively. This will be due to both the lingering weakness in the ridge from the previous system on Thursday, but also a more southern origination over the Texas coast that will push the core of the shortwave trough the Lower Mississippi Valley. With the core of the shortwave moving more over the region, the mid-level cap will break down more easily, and this will allow for greater MLCAPE of 500-1000 J/KG in the afternoon hours when temperatures rise into the upper 70s and lower 80s. Have went with fairly high PoP of 50 to 70 percent for areas along and north of the I-10 corridor in Southeast Louisiana and Southwest Mississippi where overall forcing and instability will be maximized. A fairly sharp cut-off in convective activity is expected to the south, and have only went with a 20 to 30 PoP for areas around New Orleans and the River Parishes Friday afternoon. PWATS will surge to around 1.75 inches, so some locally heavy downpours will be the primary concern with the deeper convection that develops. Shear values will remain limited, so severe storms are not anticipated on Friday. The trough axis will pull east of the area Friday evening, and a rapid reduction in convective activity is expected during the evening hours. The mid to upper level ridge will intensify over the region on Saturday and continue to build in strength through early next week. As this occurs, subsidence and warming aloft will begin to greatly limit convective potential over the area and also lead to very warm temperatures for this of year. Saturday will be the last day with any convective threat as another fast moving shortwave feature slides through the Mid-Mississippi Valley, but only isolated storms are expected as mid-level lapse rates start to weaken with the strengthening cap in place. By Sunday, any rain chances will be finished with the ridge fully dominating the region. Temperatures will warm into the mid 80s on Saturday, and will further warm into the upper 80s and lower 90s by Monday. With onshore flow and higher dewpoints persisting through the extended period, lows will only cool into the upper 60s and lower 70s each night. It will be a very Summer-like feel out there early next week, and extra caution is advised for those working outdoors due to a lack of acclimation. A few record highs could be approached or broken. && .AVIATION... (00Z TAFS) Issued at 635 PM CDT Wed May 1 2024 Most or all of the afternoon cumulus clouds will dissipate over the next hour or so. There continues a potential for radiational type fog during the late overnight hours with IFR or lower conditions beyond about 08z Thursday. Improvement to MVFR, then VFR at most terminals during the morning hours on Thursday. Potential exists for scattered thunderstorms to impact northwestern terminals during the afternoon hours on Thursday, and will carry VCTS for several hours at KMCB/KBTR/KHDC. && .MARINE... Issued at 211 PM CDT Wed May 1 2024 A persistent surface ridge centered over the Southeast CONUS will keep southeast winds of around 10 knots in place through the weekend and into early next week. Seas will also be fairly persistent at 1 to 3 feet through the period. Overall, no significant concerns to maritime operations are anticipated through early next week. && .PRELIMINARY POINT TEMPS/POPS... MCB 63 84 66 80 / 0 50 40 60 BTR 70 85 70 81 / 0 50 30 50 ASD 67 84 69 83 / 0 30 20 30 MSY 71 84 72 82 / 0 30 20 20 GPT 68 81 71 81 / 0 20 10 20 PQL 65 82 69 82 / 0 10 10 10 && .LIX WATCHES/WARNINGS/ADVISORIES... LA...None. GM...None. MS...None. GM...None. && $$ SHORT TERM...PG LONG TERM....PG AVIATION/UPDATE...RW MARINE...PG