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303 FXUS64 KLIX 221913AFDLIXArea Forecast DiscussionNational Weather Service New Orleans LA213 PM CDT Tue Jul 22 2025...New SHORT TERM, LONG TERM, AVIATION, MARINE....SHORT TERM...(This evening through Wednesday night)Issued at 100 PM CDT Tue Jul 22 2025Another warm and humid Summer day out there with the area in the lower to even mid 90s by 18z. A few more degrees and much of the area should be in the mid 90s with a few possibly hitting around 97-98 degrees but those warmer ambient temps may be a little easier to hit tomorrow. As for tomorrow there are a few potholes out there. One the sfc tomorrow could be very hot with widespread oppressive conditions but when looking a little deeper there are more than enough cracks that give pause to how hot and oppressive it will be tomorrow. Even the models and especially the NBM aren't in great agreement as it is playing both, the hot side of the forecast, and the wet side of the forecast for some areas. The ridge will continue to dominate the region centered over the Lower MS Valley to start the day and slowly sliding north by Wednesday night. At the same time deep tropical moisture that was actually partially from the system we had last week is coming back around and will begin to move into the area for the 2nd half of the work week underneath the ridge. First off rain chances will increase drastically this week and into the weekend as that deeper moisture pushes in but when exactly the rain moves in is a question. Unlike last week where the day before the deep tropical moisture was already on our doorstep it is far back to the east. NBM is carrying 40-60% PoPs mainly along and east of the Pearl River and across the southshore of Lake Pontchartrain. But if you currently look to our east the convection is well to the east mainly along a north/south line across the GA/AL state border and is making very slow progress west. Given that the thinking is the NBM is too fast/early with the precip tomorrow. Storms may still be likely across coastal MS but that will likely be closer to 22-00z which means we will already be on the other side of peak heating. With this we did back down PoPs some across most of the CWA or delayed it by a few hours. Any cooling from outflow rain/boundaries will likely be late in the day now. In addition not anticipating that much cloud cover either to keep the area from mixing well and heating up. The other favorable factor for heating up especially across coastal MS is the sfc/BL winds. These will be out of the north and north-northeast during the midday and afternoon hours. This provides some localized downsloping and really allows locations like PQL to heat up. We have been mixing up to h85 the last few days and with models indicating h85 temps of 21-22C. This mixed down to the sfc is 36-37C and with that it would not be a complete shock if a few locations across coastal MS (including Pearl River) possibly topped out right around the century mark. Big key will be to see how much we warm up today and if the progress of moisture/storms to the west speeds up any. On the other issues with the heat is mixing. We have already brought up the fact that we have been mixing fairly well and up to h85 but we have also been mixing down slightly drier LL air and that has been driving the dewpoints down in the lower 70s for much of our interior locations such as BTR and MCB. This is keeping the heat index in check a little and both along with numerous other locations across southwest MS and adjacent LA parishes have really struggle to get those rather oppressive heat index values. This isn't to take away from it being hot these areas are just mixing far more efficiently and have been remaining at marginal or below Heat Adv criteria. So how high does the heat index get to tomorrow in those areas, that is very valid questions. The ridge will have the strongest influence over these areas so they should have little problem heating up well with ambient temps likely in the mid to upper 90s (96 to 98 maybe a few 99s in there). But if they really do warm up that much how low will the dewpoint drop and will the heat index come close to the 113 needed for Extreme Heat criteria. Confidence in reaching those values across much of the FL parishes and southwest MS is rather low. Combine that with, if the NBM and some of the models are correct, the possibility of storms beginning from east to west earlier in the day (midday to early afternoon) drags the confidence down a little more and not just in those area but across much of the region.With respect to the Heat products for tomorrow. As mentioned confidence is not the greatest given the possible timing of convection, how hot the ambient temperature gets, and how much mixing we see to drive the dewpoints down some. That said the highest confidence in heat becoming a dangerous problem is in the same areas it has been for the past few weeks, the triangle between I 10 and 12 in SELA and along the immediate MS coast. This area is surrounded by marshes and the warmer tidal lakes and MS Sound. The higher moisture content along with the highs topping out in the mid to possibly upper 90s should yield heat index readings in the 110-115 range around midday and early afternoon. It is that area that has been upgraded to an Extreme Heat Warning. Outside of the warning the Extreme Heat Watch remains in effect given the lower confidence. Yes that looks a little odd with a Warning north of our CWA and another in the middle and southern portions of the CWA but given how much those areas of southwest MS and adjacent LA parishes have struggled to even reach Heat Adv levels and the given this forecast doesn't come close to warning criteria, just not enough there to justify the upgrade yet. Will allow the evening and overnight shifts to see how things finished this afternoon and where convection is overnight before a decision is made to go with a warning or an advisory. /CAB/&&.LONG TERM...(Thursday through Monday night)Issued at 100 PM CDT Tue Jul 22 2025Forecast looks rather wet again for much of the extended. Medium range models are in fairly good agreement and given the deep moisture to our east that is expected to move in and linger through the weekend. NBM at a glance looks good with high pops each day and any adjustments would be very minor. The controlling feature is actually the ridge that is slowly moving to the north tomorrow. This ridge will become centered over the TN Valley and the southern Appalachians Thursday and then by the end of the week and into the weekend will extend from the TX panhandle across the TN Valley and southeast off the SC/NC coast. This ridge wraps around the Gulf but yet is displaced far enough to the north that it will not suppress convection and will allow that area of deep tropical moisture to slowly drift west if not trap it. The deep moisture alone doesn't necessarily mean we will get widespread showers and thunderstorms however there is a mid lvl inverted trough that just lays up across the Lower MS Valley Friday through the weekend. This will provide lift across the region and combine that with the moisture in place numerous to widespread showers and thunderstorms should have little difficulty developing each day with storms driven diurnally, inland during the day and over the coastal waters at night. /CAB/&&.AVIATION...(18Z TAFS)Issued at 100 PM CDT Tue Jul 22 2025No concerns for any of the terminals at this time. VFR conditionsshould persist through 18z tomorrow but convection may start tomove in around ASD/GPT/MSY/NEW just before 00z Thursday. /CAB/&&.MARINE...Issued at 100 PM CDT Tue Jul 22 2025High pressure remains in control of the forecast through tomorrow,helping to keep winds light. It along with a weak area of low pressure moving along the northeastern Gulf coast will bring aboutoffshore flow tomorrow through Wednesday night. During the day Thursday that weak area of low pressure will slide west leading toonshore flow returning late Thursday and winds increasing some. SCS headlines may be needed for the open waters Thursday night andFriday. Convection will remain very isolated in nature tonight and the first half of the day Wednesday before we see tropical moisture return to the region, increasing our chances of rain and thunderstorms. /CAB/&&.PRELIMINARY POINT TEMPS/POPS...MCB 76 98 76 93 / 0 20 10 70 BTR 77 97 78 94 / 0 20 10 80 ASD 77 96 75 90 / 10 30 40 90 MSY 81 97 80 91 / 0 40 40 90 GPT 79 97 77 90 / 10 50 50 90 PQL 77 97 75 91 / 10 60 50 90 &&.LIX WATCHES/WARNINGS/ADVISORIES...LA...Heat Advisory until 7 PM CDT this evening for LAZ034>037-039- 046>048-056>060-064-065-071-076>090.GM...None.MS...Heat Advisory until 7 PM CDT this evening for MSZ068>071-077- 083>088.GM...None.&&$$SHORT TERM...CABLONG TERM....CABAVIATION...CABMARINE...CAB
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Topic: [Alert]LIX issues Area Forecast Discussion (AFD) at Jul 22, 2:13 PM CDT ...New SHORT TERM, LONG TERM, AVIATION, MARINE... (Read 139 times)
