Area Forecast Discussion
Issued by NWS New Orleans/Baton Rouge, LA

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560 FXUS64 KLIX 180913 AFDLIX Area Forecast Discussion National Weather Service New Orleans LA 413 AM CDT Tue Jun 18 2024 ...New SHORT TERM, LONG TERM, MARINE... .SHORT TERM...
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(Today through Wednesday) Issued at 405 AM CDT Tue Jun 18 2024 Upper ridging centered over the Carolinas this morning with a trough over the Rockies and Intermountain West. Still have the low over the Bay of Campeche that has been designated Potential Tropical Cyclone One. Still have a fairly significant surface pressure gradient between the Bermuda High and the circulation over the Bay of Campeche, although winds haven`t been quite as strong as anticipated to this point. We continue to be in a very moist airmass with precipitable water values near or above 2.10 inches, which is above the 90th percentile for mid June and approaching the daily maxima. Similar to last night, an impulse is noted on water vapor imagery moving northward through the lower Mississippi River Valley that took most of the earlier rain with it. However, we can see on radar, indications of the next impulse moving into the southern portion of our coastal waters at 3 AM CDT. Temperatures at that time were mainly ranging from the mid 70s to around 80. The upper ridge to the east may nudge the cyclonic flow with the system to our southwest a bit further westward over the next 36 hours. That may not be particularly noticeable in forecast precipitable water values today, as they remain in excess of 2 inches, but we do expect a noticeable drying across at least the east half of the area on Wednesday, when precipitable water values fall to about 1.7 inches. Still expect pretty extensive coverage of showers and a few storms today, especially once we get some heating. Most areas should see less than an inch of rain today, but highly efficient rainfall rates could produce a brief problem or two. Areal coverage and rainfall amounts on Wednesday should be somewhat less than today, and shifted westward. High temperatures today, even with the occasional showers and storms, should at least get into the 85 to 90 range, and probably a degree or two higher on Wednesday.
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&& .LONG TERM...
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(Wednesday night through Monday) Issued at 405 AM CDT Tue Jun 18 2024 The ridging off to our northeast appears to strengthen a bit, and retrograde westward over the next few days. This suppresses the circulation to the southwest enough to force it into Mexico. It also serves to dry our airmass somewhat, especially north of the Interstate 10/12 corridor. In those areas, we may not see much in the way of rain for at least Thursday through much of the weekend. South of there, moisture levels may remain high enough, precipitable water values in the 1.5 to 1.8 range, to support isolated to scattered afternoon showers/storms, especially along lake/sea breeze boundaries. NBM PoPs may be a bit overdone over the weekend, but current forecast is in agreement with neighboring offices. As ridging continues to push westward, moisture levels will again be on the upswing early next week with a resulting increase in areal coverage of convection. With the somewhat drier airmass pushing into the area, high temperatures will return to the lower and middle 90s going into the weekend. dew points may settle a little lower, but we may get close to heat advisory criteria over the weekend.
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&& .AVIATION... (06Z TAFS) Issued at 1134 PM CDT Mon Jun 17 2024 Convection has become more scattered this evening. Mostly light to moderate rainfall continues generally across coastal Louisiana. TS should be mostly limited tonight. Convection looks to again be possible on Tuesday with the best potential over the south/western terminals such as BTR and HUM. Could see brief MVFR CIG/VIS in the heaviest convection. Southeasterly winds will increase and become gusty with some of the southern terminals approaching gusts in excess of 30 kts. (Frye) && .MARINE...
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Issued at 405 AM CDT Tue Jun 18 2024 Over the last 24 hours, winds haven`t been quite as strong across the coastal waters as earlier anticipated, mainly in the 20 to 25 knot range. With PTC One not expected to significantly strengthen, confidence in gale conditions occurring is not strong enough at this time to justify gale watches/warnings. Have coordinated with WFO LCH to hold with strongly worded Small Craft Conditions at this time. Can`t entirely rule out the eventual need for gales, especially late tonight or tomorrow. Hazardous conditions are expected over much of the open waters for the next several days, however, and Advisories may need to be extended beyond the current expiration over some or most of the waters. No changes to Coastal Flood Products at this time, as current forecast levels continue to be 1-2 feet above normal, which fits advisory criteria.
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&& .PRELIMINARY POINT TEMPS/POPS...
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MCB 85 71 90 71 / 50 10 20 0 BTR 87 76 92 77 / 70 20 40 0 ASD 88 76 90 75 / 70 10 60 10 MSY 88 81 90 81 / 70 20 70 20 GPT 88 77 90 77 / 60 20 50 20 PQL 92 75 93 74 / 40 10 30 20
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&& .LIX WATCHES/WARNINGS/ADVISORIES...
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LA...Coastal Flood Advisory until 4 PM CDT Wednesday for LAZ066>070- 076-078. GM...Small Craft Advisory from 7 AM this morning to 7 AM CDT Thursday for GMZ530-532-534. Small Craft Advisory until 7 AM CDT Thursday for GMZ536-538-550- 552-555-557-570-572-575-577. MS...Coastal Flood Advisory until 4 PM CDT Wednesday for MSZ086>088. GM...Small Craft Advisory from 7 AM this morning to 7 AM CDT Thursday for GMZ532-534. Small Craft Advisory until 7 AM CDT Thursday for GMZ538-550-552- 555-557-570-572-575-577.
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&& $$ SHORT TERM...RW LONG TERM....RW AVIATION...RDF MARINE...RW