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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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189 FXUS64 KLIX 300456 AFDLIX Area Forecast Discussion National Weather Service New Orleans LA 1156 PM CDT Sat Jun 29 2024 ...New AVIATION... .SHORT TERM... (This evening through Sunday night) Issued at 341 PM CDT Sat Jun 29 2024 Main concern in the short term continues to be heat and humidity. While afternoon highs are only a couple degrees warmer than normal for this time of year, a very humid airmass is in place, with dewpoints in the mid to upper 70s. These high dewpoints have a twofold effect on the heat across the area - 1) it limits overnight cooling and 2) it results in high heat index values during the afternoon. Have upgraded the excessive heat watch to an excessive heat warning for areas generally along/south of the I-10/12 corridor but away from the immediate coast of SE LA, and also along the Atchafalaya River up through Wilkinson County. In these areas, higher dewpoints will combine with afternoon temperatures to result in heat index values of 110-115. While not everywhere in the warning will reach warning criteria (heat index of 113 or higher), there is enough threat that it seems warranted, especially since the overnight lows across most of the warning area will struggle to drop below 80 degrees. Those most vulnerable to heat effects will be the elderly, very young, and also those who are ill. The overnight lows will be especially impactful for those who lack access to adequate air conditioning since the warm temperatures will limit their ability to cool their bodies even overnight. With ample moisture in place, expect afternoon showers and storms to develop again tomorrow. However, onset will again be delayed until generally mid to late afternoon due to weak subsidence aloft associated with the high pressure centered to our north. Any showers/storms that develop will have plenty of moisture to work with, so while area average rainfall will be low, a few places could see half an inch or more in a relatively short period. && .LONG TERM... (Monday through Friday night) Issued at 341 PM CDT Sat Jun 29 2024 The northern stream upper level trough moves through the Great Lakes Sunday evening and continue eastward into the Atlantic Ocean Monday. The base of this trough doesn`t reach much farther south than the Appalachian Mountains as it shifts offshore. This track is why a weak backdoor front comes into the CWA from the northeast just ahead of the trailing ridge. That upper ridge, in the wake of this trough, will be sliding east across the entire Mississippi Valley Monday afternoon into Tuesday. Global models have been extremely consistent from run to run for a few days now showing a 596dm high will be centered near the Akrlatex region Monday afternoon. Excluding rain potential, increasing 500mb heights will bring already above normal weekend temps up even more. Guidance spread through the forecast period is fairly minimal and as of 12z runs, Monday has the potential to be the warmest with highs mid/upper 90s to 100 degrees which is nearly 10 degrees above normal. Convective coverage will probably be the bigger deciding factor on max temps and heat impacts. That previously mentioned weak backdoor front looks to stall near the Gulf Coast, which combined with forecast temps, would support scattered to numerous showers and storms. If convective initiation is early enough, heat indicies will get knocked down quickly. However, if not too early, widespread upper 70 to 80 degree dewpoints with hot temps may bring heat indicies well into Heat Advisory range and possibly many areas with Excessive Heat Warning temps. Tuesday will virtually mirror Monday as the upper ridge just slides slightly eastward. Still looking at the same heat/convection timing challenges in the late morning and afternoon hours. As the rest of the week progresses, repeated northern stream troughs/shortwaves will steadily flatten out the ridge aloft and eventually cause it to retrograde to the west. As the subsidence slowly fades from this upper level pattern change, should eventually see some less extreme temps and more widespread daily convection. && .AVIATION... (06Z TAFS) Issued at 1154 PM CDT Sat Jun 29 2024 All of the convection across the area has dissipated shortly after sunset. VFR conditions will prevail tonight and into tomorrow. Similar to yesterday, convection is expected to initiate around 18-19z tomorrow when the convective temperature is reached. Pinpointing where this will occur is a challenge, thus only VCTS was mentioned. Expect that activity to continue until the sun goes down around 02-04z. && .AVIATION... (00Z TAFS) Issued at 655 PM CDT Sat Jun 29 2024 Currently none of the convection across the area is impacting any terminals this evening. Expect that convection to dissipate shortly after the sun goes down. VFR conditions will prevail tonight and into tomorrow. Similar to today, convection is expected to initiate around 18-19z tomorrow when the convective temperature is reached. Pinpointing where this will occur is a challenge, thus only VCTS was mentioned. Expect that activity to continue until the sun goes down. && .MARINE... Issued at 341 PM CDT Sat Jun 29 2024 Daily thunderstorms will continue to be the primary concern across marine areas. Otherwise, conditions will remain fairly benign with gradient winds no higher than 10-15 knots and waves/seas mostly 3 ft or less. && .PRELIMINARY POINT TEMPS/POPS... MCB 92 75 93 76 / 50 20 60 20 BTR 96 80 98 79 / 50 20 50 20 ASD 94 81 95 80 / 60 20 50 20 MSY 94 81 95 83 / 50 10 60 20 GPT 92 80 95 80 / 50 20 60 30 PQL 95 80 97 79 / 50 20 60 40 && .LIX WATCHES/WARNINGS/ADVISORIES... LA...Excessive Heat Warning from 10 AM to 7 PM CDT Sunday for LAZ034- 035-046>048-056>060-064-065-076>090. Heat Advisory from 10 AM to 7 PM CDT Sunday for LAZ036-037-039- 066>071. GM...None. MS...Excessive Heat Warning from 10 AM to 7 PM CDT Sunday for MSZ068- 083>088. Heat Advisory from 10 AM to 7 PM CDT Sunday for MSZ069>071-077. GM...None. && $$ SHORT TERM...DM LONG TERM....ME AVIATION...JZ MARINE...DM