Area Forecast Discussion
Issued by NWS New Orleans/Baton Rouge, LA
Issued by NWS New Orleans/Baton Rouge, LA
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618 FXUS64 KLIX 132048 AFDLIX Area Forecast Discussion National Weather Service New Orleans LA 348 PM CDT Thu Jun 13 2024 ...New SHORT TERM, LONG TERM, MARINE... .SHORT TERM... (This evening through Friday night) Issued at 149 PM CDT Thu Jun 13 2024 In a nutshell, hot. In more detail....An upper level ridge of high pressure will build eastward into the area becoming more centered over the lower Mississippi Valley tomorrow and especially Saturday. With the high centered near the region, subsidence aloft will suppress convection and POPs are generally 10 percent or less through the weekend. The lack of showers/storms and cloud cover will also allow temperatures to rise into the mid to upper 90s and a couple places may even touch the century mark on Saturday. While dewpoints won`t be pleasant, slightly drier air mixing down from aloft during the afternoon should help keep the heat index from rising to oppressive levels. Current forecast calls for max heat index readings in the 98 to 102 range on Friday and in the 100 to 105 degree range on Saturday. && .LONG TERM... (Saturday through Wednesday night) Issued at 149 PM CDT Thu Jun 13 2024 Saturday evening, upper ridging will be centered over Alabama and moving northeastward to West Virginia by Tuesday and over the Mid Atlantic States by mid to late week next week. That will eventually open up the local area to mid-level easterlies by Sunday or Monday. By early next week, the Central American Gyre will likely aid in the development of low pressure in the Bay of Campeche. The easterlies should be sufficient to move any low pressure that does develop westward into Mexico by mid to late week next week. The low will strengthen the surface pressure gradient between it and the Bermuda High. The low level onshore flow will allow moisture levels to rapidly increase from about 1.4 inches Saturday evening to about 2 inches by Monday evening, and remaining in the 2.0 to 2.2 range near and south of Interstate 10 through midweek next week. As shortwaves move westward through the easterlies, they will produce rounds of rain and thunderstorms. There have been differences between the GFS and ECMWF families regarding the strength of the ridge to the northeast and how quickly they move away, with the ECMWF based solutions generally stronger with the ridging. These solutions tend to keep the focus of heavier rain amounts generally over the Gulf of Mexico and/or west of our CWA. Over the last couple of days, the area of heaviest rainfall has gradually shifted westward in both the NBM and WPC solutions. That`s certainly not to say we are looking at a dry week by any means, but any heavy rain/flooding threat doesn`t appear to be quite as high as it appeared a couple days ago. The heaviest rain amounts at this point in our area look to be perhaps a general 2-3 inches between Interstate 10 and the Louisiana coast, with lighter amounts to the north, although there is still some uncertainty involved in the forecast. As moisture levels increase, this will likely have a significant impact on low temperatures near south of Interstate 10 from Saturday night onward until we get out of the wetter pattern, with overnight lows 75 to 80 (and maybe a few lower 80s) common for much of that area. We`ll likely have one more day of above normal high temperatures on Sunday with highs in the mid 90s if precipitation holds off long enough. Convective temperatures are forecast to fall off to around 90 on Monday for most of the area, and into the mid to upper 80s for the middle of next week. Any areas that are fortunate enough to not get rained on during a particular midday period could get a little warmer than those values, but not much. As guidance has been drifting toward the previous ECMWF solutions, the slightly warmer NBM readings vs GFS seem to be the way to go. && .AVIATION... (18Z TAFS) Issued at 1239 PM CDT Thu Jun 13 2024 All terminals currently VFR. However, the higher moisture content across the southeast half of the area has become apparent over the last hour or so with a fairly widespread cumulus field southeast of a KMCB-KBTR line, where most cloud bases are well above FL030. We`ve even seen a few SHRA/TSRA south of Lake Pontchartrain that will be close enough to KMSY and KHUM to justify at least VCTS for the next few hours. It appears that light northwest winds may provide enough of a lake shadow the next few hours to keep cells far enough away from KNEW to leave them out of that terminal area. Forecast soundings do show lower precipitable water values progressing southeastward during the afternoon hours and convective areal coverage should diminish prior to sunset. Should see VFR conditions overnight, and little or no SHRA/TSRA development tomorrow. && .MARINE... Issued at 149 PM CDT Thu Jun 13 2024 High pressure building into the area will keep conditions generally benign through Saturday with light winds and seas 2 feet or less, though a few showers/storms could produce locally higher winds and seas, mainly across the outer waters. As the high shifts eastward on Sunday in response to a broad low developing over the Bay of Campeche, the pressure gradient will tighten somewhat and cause winds to strengthen to 10 to 15 knots. Additionally, a surge of deeper moisture will result in higher rain chances by Sunday as well. Expect the moderate onshore flow to persist through the early part of the week, with potential for strengthening to advisory criteria in the Monday/Tuesday time frame. Will need to keep an eye on the tides going into Monday and especially Tuesday. If the moderate to strong southeast winds persist as currently forecast, minor coastal flooding would be possible. && .PRELIMINARY POINT TEMPS/POPS... MCB 67 94 70 96 / 0 0 0 10 BTR 72 97 75 99 / 0 0 0 10 ASD 73 96 74 98 / 0 0 0 10 MSY 78 95 79 96 / 10 0 0 10 GPT 74 95 76 95 / 0 0 0 10 PQL 71 98 73 99 / 0 0 0 10 && .LIX WATCHES/WARNINGS/ADVISORIES... LA...None. GM...None. MS...None. GM...None. && $$ SHORT TERM...DM LONG TERM....RW AVIATION...RW MARINE...DM