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Area Forecast Discussion
Issued by NWS New Orleans/Baton Rouge, LA
Issued by NWS New Orleans/Baton Rouge, LA
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789 FXUS64 KLIX 290505 AFDLIX Area Forecast Discussion National Weather Service New Orleans LA 1205 AM CDT Wed May 29 2024 ...New AVIATION... .SHORT TERM... (This evening through Wednesday night) Issued at 400 PM CDT Tue May 28 2024 Convection is firing as expected across the area just a tad farther to the southwest than initially expected but there is still quite a bit of convection off to the west trying to slide towards our area. Thee is still a convergent line in the LL just south of the Southshore (NO metro) and runs WNW to LFT. This has nudged south from where it was a few hours earlier and it will likely keep the strongest convection contained to area along and south of I-10 with little if anything around I-12 and especially north of that for the remainder of the afternoon and through the evening. Storms that have fired off to our west have had a history of producing severe hail and severe winds with hail up to 1.25" so far but multiple reports of winds 50 to 60 and a peak wind speed near Beaumont of 73 mph! The closest report to our CWA so far has been New Iberia (ARA) with a measurement of 58 mph at the ASOS. After we start to lose the daytime heating these storms will begin to wane and could dissipate quickly as there is no real disturbance associated with this activity as they have been almost been exclusively driven by mesoscale features such as boundary collision (sea, lake, outflow, differential heating, etc). The atmosphere is just juicy enough that storms just needed to get going and then the storms could basically provide the rest until we lose the instability. Tomorrow and Thursday we will continue to see the possibility of convection and just like today and yesterday it will primarily be driven by what develops overnight upstream across TX, Red River Valley, and Arkansas. The digging L/W trough over the eastern CONUS will try to place the area under weak northwest flow and this usually leads to convection being later, sometimes much later in the day. But the ridging over the western Gulf may nudge north into the area and this could suppress convection but the key will be if convection to our northwest dives southeast eroding the s/w ridging or if the ridging is too strong and forces most of the convection more south just off to our west. Thursday seems to be fairly similar but possibly a touch better for rain potential as we should at least see the Gulf ridge retro grade with much more energy working to the Plains and southern Plains Wednesday night through Thursday. Again the thing to watch will be convection upstream as that will dictate what happens here. As for the potential for strong to severe this risk should not be as impressive as today with not as favorable mid lvl lapse rates, slightly cooler temps leading to less instability over the area as well. Only thing to keep an eye on is the possibility of the seabreeze activating. With the sfc high becoming established across the CONUS between the MS Valley and the Appalachians we will see onshore flow return with mostly southerly winds from the sfc to h85 and this could help provide enough LL convergence and forcing to get a few storms to pop but with that and the possibility of weak northwest flow, wouldn`t anticipate much convection until at least the afternoon if not mid afternoon. /CAB/ && .LONG TERM... (Thursday through Monday night) Issued at 400 PM CDT Tue May 28 2024 Forecast is not getting any easier in the extended portion of the forecast. Some of the medium range models have trended in the opposite direction from where they were the past 48 hours with the ECMWF trending wetter for Friday and the GFS now slightly drier (not dry just not quite as bullish as yesterday). That said there is more confidence now that ridge building west of the current eastern CONUS L/W trough will not be quite as stout and the base will be north of the region. This provide weak northwest to possibly mostly zonal flow and thus any disturbances that dig into the southern Plains and central/east TX should be able to undercut the ridge enough to push into our area. Again looking at the NBM and it has increased the PoPs for almost each through Sunday. With the increase in confidence in the pattern this is a good trend and will stick with the 40 to even 60% PoPs it is advertising at times. The biggest question is the afternoon highs. These will absolutely be dictated by timing over convection and cloud cover and with no confidence at all in the overall timing best option is to stick with what the NBM has however if we have a great deal of cloud cover and rain most of these daily highs in the forecast will likely be too warm. On the other side with the LL temps being advertised if we find ourselves in a break at the wrong time (basically mid morning through the afternoon) the current forecast is a few degrees too cool. Friday may be the one day with the least amount of convection. The L/W trough will dig across the eastern seaboard and the ridge will amplify in response but as long as it is connected with the broad riding to the SSW over the Gulf and across Mexico we should still be able to get some afternoon convection. LL temps of 22-24 would suggest highs in the upper 80s to maybe mid 90s but with the expectation of clouds and storms providing cooling rain mid 80 to near 90 is probably the right call. This weekend looks to provide one possibly two good shots of rain across the area. The trough currently coming onshore out of the Pacific will work across the CONUS over the next few days and there may actually be multiple impulses associated with it as it tries to merge with some energy coming out of the Pacific over Mexico and southern TX. Multiple things being to take place late Friday and into the weekend. First our L/W trough over the east coast slides east into the Atlantic with the ridge continuing to work east as well. This will lead to less of an impact from the ridge. In addition the ridge over Mexico builds but is centered along the western Mexican coast with the ridge axis building into the 4 corners late Saturday. This will help to place the CWA in northwest flow but there will be a few disturbances that work through the Lower MS Valley. Timing these right now is futile but when these occur we can expect to see scattered to numerous storms across the region. Good thing is as of right now it doesn`t look like there is that much of a threat of strong to severe storms. Biggest impact could be in the form of heavy rain. /CAB/ && .AVIATION... (06Z TAFS) Issued at 1202 AM CDT Wed May 29 2024 All convection has died at this point leaving conditions quiet. VFR conditions expected through the forecast period with light winds less than 5kts and high clouds if any for most areas. && .MARINE... Issued at 400 PM CDT Tue May 28 2024 No major concerns over the coastal waters outside of convection. The one thing to keep a close eye on is the possibility of a wake low tonight if current convection over south-central and southeast LA starts to surge to the southeast again. The is a rather impressive meso high behind the convection and if this continues we could see a wake low develop providing a 2-3 hours window of strong winds over the coastal waters west of the mouth of the MS this evening. High pressure will be come re-established well off to our north and northeast and onshore flow will redevelop and become moderate at times through the rest of the week and into the weekend. /CAB/ && .PRELIMINARY POINT TEMPS/POPS... MCB 66 87 66 86 / 20 50 20 40 BTR 73 89 72 90 / 20 60 10 40 ASD 71 90 71 91 / 10 30 20 30 MSY 76 91 74 90 / 10 40 20 40 GPT 73 88 71 88 / 10 20 20 30 PQL 69 91 69 90 / 10 20 20 20 && .LIX WATCHES/WARNINGS/ADVISORIES... LA...None. GM...None. MS...None. GM...None. && $$ SHORT TERM...CAB LONG TERM....CAB AVIATION...HL MARINE...CAB