Area Forecast Discussion
Issued by NWS New Orleans/Baton Rouge, LA
Issued by NWS New Orleans/Baton Rouge, LA
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138 FXUS64 KLIX 092120 AFDLIX Area Forecast Discussion National Weather Service New Orleans LA 320 PM CST Sat Nov 9 2024 ...New SHORT TERM, LONG TERM, MARINE... .SHORT TERM... (This evening through Sunday night) Issued at 305 PM CST Sat Nov 9 2024 Tropical Storm Rafael, now with its center exposed, continues to weaken over the central Gulf of Mexico and will come to almost a complete halt, at least briefly, over the next 12-24 hours. A deep upper low was over Nebraska this afternoon, and was pulling moisture from Rafael northward across Louisiana ahead of a frontal boundary along the Texas border. Precipitable water values near climatological maxima for mid-November of 2.1 inches or higher, per LCH sounding, have aided in the production of heavy rainfall across western Louisiana with ground truth reports of 2 to 4 inches or more have been noted since 6 AM CST. Meanwhile, the morning soundings at LIX and JAN showed drier air between 700 and 900 mb, with precipitable water values closer to 1.6 inches. The shortwave moving through the upper trough will lift to the northeast overnight with probably a 6 hour period of heavy rainfall potential for the extreme northwest portion of the CWA. There`s likely to be a fairly sharp cutoff between excessive rainfall and comparatively light totals. While the main threat area is likely to be just west of our area in the LCH CWA, it`s entirely too close to call as whether any heavy rain occurs within our CWA. Have opted to issue a Flood Watch for Excessive Rainfall for a couple southwest Mississippi counties and adjacent southeast Louisiana parishes overnight through midday Sunday. At this point, the threat appears to be lower for the Baton Rouge and McComb areas, but the threat there is non-zero. Certainly can`t rule out 2 to 4 inch totals with spot amounts much higher wherever the heaviest band sets up. Low level moisture will remain across the area through Sunday night, but forcing diminishes Sunday morning. Mostly cloudy skies with scattered showers are likely to be the end result for the afternoon and overnight hours as drier air only slowly filters in from the west. Temperatures tonight and Sunday will continue to be near record warmth, but overnight lows Sunday night may finally return to the 60s, instead of breaking records. With wind fields subsiding over the next 24 hours, and astronomical tide ranges diminishing, the threat for minor coastal flooding should gradually subside as well. Will leave current advisories in place, but do not anticipate additional issuances. && .LONG TERM... (Monday through Friday night) Issued at 305 PM CST Sat Nov 9 2024 Rafael finally gets out of the way on Monday with ridging building over the northern Gulf of Mexico with zonal flow to the north of that. An active northern stream will move s strong shortwave across the center of the country Tuesday and Wednesday, likely pushing a cold front through the area Wednesday night. Latest model guidance arriving in the last hour or so is coming in wetter than the nearly dry forecast we`ve had riding, so it is entirely possible that in the next forecast package or two, rain chances will need to be increased significantly. Other than that frontal passage, the forecast is likely to be dry going into the weekend. Monday high temperatures will be only slightly cooler than the last few days, but humidity values should be somewhat lower. For mid and late week, the operational GFS and ECMWF solutions have essentially swapped positions, with the ECMWF solution now being the cooler of the two, with readings closer to normal. There`s quite a spread in low temperatures within the respective ensembles for Wednesday night through Friday night, so forecast confidence leaves a little to be desired. A little better agreement on high temperatures with most of the area probably in the 70s. && .AVIATION... (18Z TAFS) Issued at 1219 PM CST Sat Nov 9 2024 Ceilings have generally improved to MVFR or VFR this afternoon as temperatures have warmed. Can`t rule out a few showers, but any impactful precipitation likely to hold off until well after sunset. Main threat of TSRA would be for KBTR during the overnight hours with potential for IFR or lower ceilings and visibilities. All terminals could see some flight restrictions in rain Sunday morning. While MVFR conditions are likely at that time, IFR is certainly a possibility. Gusty winds to 25 knots are likely this afternoon at KMSY/KNEW/KHUM, but we should see those subside somewhat after sunset. && .MARINE... Issued at 305 PM CST Sat Nov 9 2024 As Rafael gradually winds down over the next 36 hours or so, wind fields should similarly weaken. However, it will take some additional time for seas to subside. We will keep the Small Craft Advisory in place through mid-morning Sunday, but may need an extension of the advisory for seas in the outer waters. Beyond that point, should be a bit quieter few days until after the cold front passage toward the middle or end of the workweek. && .PRELIMINARY POINT TEMPS/POPS... MCB 69 78 64 77 / 70 70 50 30 BTR 74 83 67 82 / 70 60 30 20 ASD 73 81 67 80 / 50 60 40 30 MSY 75 82 70 79 / 60 60 40 30 GPT 73 80 67 79 / 30 60 40 30 PQL 73 83 67 84 / 20 50 30 30 && .LIX WATCHES/WARNINGS/ADVISORIES... LA...Flood Watch from 6 PM CST this evening through Sunday morning for LAZ034>036. Coastal Flood Advisory from 9 PM this evening to 10 AM CST Sunday for LAZ057-058-060-066>070-076>078-080-082-084-086- 087. Coastal Flood Advisory from 9 PM Sunday to 9 AM CST Monday for LAZ066>070-076-078. GM...Small Craft Advisory until 10 AM CST Sunday for GMZ550-552-555- 557-570-572-575-577. MS...Flood Watch from 6 PM CST this evening through Sunday morning for MSZ068-069. Coastal Flood Advisory from 9 PM this evening to 10 AM CST Sunday for MSZ086>088. Coastal Flood Advisory from 9 PM Sunday to 9 AM CST Monday for MSZ086. GM...Small Craft Advisory until 10 AM CST Sunday for GMZ552-555-557- 570-572-575-577. && $$ SHORT TERM...RW LONG TERM....RW AVIATION...RW MARINE...RW