Area Forecast Discussion
Issued by NWS Lake Charles, LA
Issued by NWS Lake Charles, LA
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547 FXUS64 KLCH 170422 AFDLCH Area Forecast Discussion National Weather Service Lake Charles LA 1122 PM CDT Sun Jun 16 2024 ...New AVIATION... .SYNOPSIS... Issued at 405 PM CDT Sun Jun 16 2024 A disturbance coming out of the Central American Gyre is expected to move gradually west-northwest across the southern and western Gulf of Mexico through mid week. As of the last TWO, NHC has given tropical cyclone formation for the next 48 hours at 30 percent and through the next 7 days at 70 percent. The consensus looks like if the system does form a closed off low it will move into the northeast Mexico coast. However, it also looks like it will remain sloppy with most of the higher moisture and higher winds off and maybe well off to the north. Therefore, impacts as far as heavy rainfall that may lead to flooding, high wave heights, and high tides that may lead to coastal flooding are also possible. Both high rainfall rates and duration may be factors through mid week, along with high tide levels along the coast not allowing for proper drainage of river systems. Reasonable rainfall totals of 5 to 8 inches for lower southeast Texas and lower southwest Louisiana through Wednesday night, with 2 to 4 for the remainder of the forecast area. A Moderate Risk of Excessive Rainfall (Level 3 of of 4) is outlined for that lower southeast Texas and southwest Louisiana area, with greater potential from Tuesday morning through Tuesday night. If this risk continues then a Flash Flood Watch will be issued as we get closer to the event and confidence grows in the flood potential. There will also be increased winds and seas over the coastal waters, along with increased in tides and potential for coastal flooding. Please see the marine section for more details. Rua && .SHORT TERM... (Tonight through Tuesday night) Issued at 405 PM CDT Sun Jun 16 2024 Forecast in the short term will depend on how the disturbance in the southern Gulf develops over the period. For now will go with the scenario that system remains sloppy with best moisture plume extending well off to the north. The upper level ridge over the northwest Gulf continues to weaken today allowing highly anomalous moisture to move into the forecast area. This moisture has already worked with daytime heating and the sea breeze to produce shower and storm activity. This activity is expected to weaken this evening with the loss of daytime heating. Rich Gulf moisture will hang around into Monday allowing for widespread shower and storm activity to develop by mid to late morning and expand during the afternoon. Heavy rainfall will be the main concern from the activity with a quick 1 to 2 inches in a short period will be possible. The deeper tropical moisture plume will over take the forecast area on Tuesday. The air mass will definitely have a tropical origin to it with highly anomalous moisture values. Precipitable Water values will range from 2.2 to 2.5 inches which is well above the 90th percentile for this time of year of around 2 inches, and closer to max moving averages and daily highs. Also, 1000-500 mean layer relative humidity values will be over 90 percent and warm cloud layer depth will be between 14k-16k feet, which all means that convection will be highly efficient warm process rain makers. Right now, the higher moisture values are focusing on lower southeast Texas and lower southwest Louisiana, where also the better 85H-70H southeast flow will be parallel to the developing theta-e ridge, allowing for a possibility of training. With these possibilities a Moderate Risk (level 3 out of 4) is already outlined for that area, and a flash flood watch may be needed as we near closer to the event. Usually in these air masses, plenty of nocturnal activity will occur over the Gulf and right along the coast. Therefore, expect plenty of showers and a few storms over the coastal waters and just inland during the overnight hours. With low convective temperatures, this activity will spread quickly inland through the morning hours and continue into the afternoon before some decrease in activity during the evening with loss of any daytime heating. Some breezy winds may occur right along the coast, and also during any convection some of the stronger winds may be brought down to the surface. If there is some good news, high temperatures should be a little below normal and stay in the 80s. Rua && .LONG TERM... (Wednesday through next Saturday) Issued at 405 PM CDT Sun Jun 16 2024 The start of the longterm period carries the remainder of widespread showers and thunderstorms from disturbance navigating the western Gulf of Mexico. Regardless of whether a closed low pressure center develops in the short term, guidance continues the trend of pushing this system into either eastern Mexico or southeast Texas late Wednesday into Thursday. The large northward displacement of rainfall away from the low will be the driver for rain chances Wednesday with some influence for Thursday. Global models keep an airmass with PWATs well above 2.25 inches (greater than the daily climo max) entrenched over the region in conjunction with rainfall for at least Wednesday, thus we can expect very efficient rain rates and flooding concerns to prevail. High pressure ridges over the seUS and into Mississippi by Thursday. This feature and east to northeast flow aloft will help to move some dry(er) air into the region with forecast PWATs Thursday ranging from 1.60 to 1.75 inches in cenLA to around 2.00 inches at the coastline. With ridge and aforementioned airmass moving in from the north and east, the efficiency and northward extent of convection should be limited to typical afternoon convection along the coastline and I-10 corridor Thursday and Friday. Longterm models continue hinting at the possibility of another inverted trof moving along the northern Gulf of Mexico over the next weekend. If this solution is correct, another period of heavy rain and widespread showers and thunderstorms will be possible. Rain-and-cloud-cooled temperatures in the 80s on Wednesday will give way to highs closer to climate normals in the lower 90s for the remainder of the work week and weekend. 11/Calhoun && .AVIATION... (06Z TAFS) Issued at 1105 PM CDT Sun Jun 16 2024 A thunderstorm is located near LCH otherwise conditions are VFR across the region. The next round of showers will being near sunrise as showers move onshore. Rainfall will be persistent with occasional thunder. Other than convection conditions will be VFR across the region with south winds. && .MARINE... Issued at 405 PM CDT Sun Jun 16 2024 A trough from a disturbance moving out of Central America will gradually move west-northwest across the southern and western Gulf of Mexico from early to mid week. The gradient between the trough and high pressure to the northeast will bring moderate to strong east to southeast winds at or above 20 knots by Monday afternoon, that will continue through mid week. This prolonged wind field will allow for a significant increase in wave heights and swells. Wave heights are expected to be 4 to 8 feet on Monday increasing to 6 to 12 feet on Tuesday and Wednesday. A small craft advisory is in effect. Also, with the long duration and fetch of the easterly winds, Ekman spiral affects will allow for water piling along the coast increasing tide levels. Tides will be around 2 feet above astronomical predicted levels. P-ETSS guidance shows actual tide levels during high tide times staring late Monday night through Wednesday at 1.5 to 2.0 Mean Higher High Water (MHHW) which are in coastal flood advisory category, with 10 percent exceedance, reasonable highest tide levels possible, in the 2.5 to 3.5 MHHW which would be over coastal flood warning criteria. Currently a coastal flood advisory will be in effect for Monday night through Wednesday, and portions of it, especially the Cameron Parish and Jefferson County coast may be upgraded to a coastal flood warning as we get closer to the event. Deep moisture will also be associated with this system that will bring widespread shower activity across the coastal waters through mid week. Rua && .PRELIMINARY POINT TEMPS/POPS... AEX 73 88 71 83 / 20 80 20 60 LCH 76 87 74 83 / 40 80 50 80 LFT 75 88 76 84 / 40 80 50 80 BPT 76 88 75 84 / 50 80 50 80 && .LCH WATCHES/WARNINGS/ADVISORIES... LA...Coastal Flood Advisory from 1 AM Tuesday to 4 PM CDT Wednesday for LAZ073-074-252>254. TX...Coastal Flood Advisory from 1 AM Tuesday to 4 PM CDT Wednesday for TXZ615. GM...Small Craft Advisory from 1 PM Monday to 7 AM CDT Thursday for GMZ450-452-455-470-472-475. && $$ SHORT TERM...07 LONG TERM....11 AVIATION...14