Sunrise 6:26 AM   Sunset 7:34 PM Moonrise 3:51 PM   Moonset 3:49 AM

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GMZ530 Lake Pontchartrain And Lake Maurepas- 939 Am Cdt Sat Apr 20 2024
Today - North winds around 5 knots, becoming east around 5 knots this afternoon. Waves 1 foot or less. A slight chance of showers late this morning and afternoon. Tonight - East winds 5 to 10 knots, becoming northeast after midnight. Waves 1 foot or less, then around 2 feet after midnight. A slight chance of showers in the evening, then a chance of showers after midnight. Sunday - North winds 10 to 15 knots with gusts up to 20 knots. Waves 3 to 4 feet. Showers likely, mainly in the morning. Sunday night - North winds 15 to 20 knots with gusts up to 30 knots. Waves 3 to 4 feet. A slight chance of showers in the evening. Monday - Northeast winds 15 to 20 knots with gusts up to 25 knots, becoming north 5 to 10 knots in the afternoon. Waves 2 to 4 feet in the morning, then 1 foot or less. Monday night - Northeast winds 5 to 10 knots. Waves 1 foot or less.Tuesday - East winds 5 to 10 knots. Waves 1 foot or less, then around 2 feet in the afternoon. Tuesday night - Southeast winds 5 to 10 knots. Waves 1 to 2 feet. Wednesday - Northeast winds around 5 knots, becoming southeast in the afternoon. Waves 1 foot or less. Wednesday night - South winds 5 to 10 knots, becoming southwest after midnight. Waves around 2 feet in the evening, then 1 foot or less.

GMZ500 939 Am Cdt Sat Apr 20 2024
Synopsis for pascagoula to atchafalaya river out 60 nm -
southeast winds of 5 to 10 knots will persist through this afternoon, but a cold front will gradually shift winds to the north tonight into tomorrow. By tomorrow night, these northerly winds will strengthen to 15 to 25 knots and then linger into Monday. By Monday night, high pressure moving over the waters will allow the winds to relax back to 10 to 15 knots and also shift winds to the northeast and eventually southeast. These southeast winds of 10 to 15 knots will then remain in place into the middle of next week.

FXUS64 KLIX 201146 AFDLIX

Area Forecast Discussion National Weather Service New Orleans LA 646 AM CDT Sat Apr 20 2024

New AVIATION

SHORT TERM
(Today through Sunday Night)
Issued at 307 AM CDT Sat Apr 20 2024

A cold front currently draped just north of the forecast area along the I-20 corridor will continue to drift south and will move through the northern third of the CWA by this evening. This southward drift will be entirely driven by density differentials between the cooler airmass to the north and the warmer and more humid airmass to the south as no strong synoptic scale forcing mechanisms are forecast to pass through the region today. As the cold pool moves into the northern third of the CWA, weak isentropic forcing over the cold pool will combine with broad region of increasing positive vorticity advection in advance of a shortwave trough kicking out of the Four Corners. This will support the development of scattered showers and possibly a weak thunderstorm by this afternoon. Overall, rainfall should not be excessive with this event with rainfall totals of less than half an inch expected. Temperatures will be slightly cooler behind the front in the upper 70s while readings ahead of the front will climb back into the mid 80s.

The shortwave energy kicking out of the Four Corners will sweep through the Lower Mississippi Valley tonight into tomorrow morning. At the same time, the development of a weak mid-level low pressure system along the 850mb frontal boundary will allow the surface front to sweep southward toward the Louisiana coast by tomorrow morning. The combination of continued isentropic forcing over the cooler low level airmass behind the front and stronger deep layer forcing in the mid and upper levels will support the development of numerous showers and a few elevated thunderstorms, especially after midnight. PoP values will peak out in the 70 to 80 percent range from midnight through Noon tonight into tomorrow morning, and QPF should peak out around an inch. A few spots may see locally higher amounts of up to 2 inches, but overall flood risk is low with this event as most of the rainfall will be stratiform in nature. Temperatures will be cooler as the front sweeps to the south with temperatures ranging from the mid 50s in Southwest Mississippi to the upper 60s along the Louisiana coast.
Overall, have stuck with a blend of the NBM 50th and 75th percentiles for tonight as rain cooled air dips down toward the dewpoint.

By tomorrow afternoon, rapidly improving conditions are expected as upper level trough axis pulls to the east and the front is driven further offshore. Mid-level flow will turn northwesterly, and this will cut off isentropic forcing and also usher in a drier airmass by tomorrow evening. Fully expect to see dry conditions over all land based zones by Sunday evening as well as clearing skies. Temperatures will be significantly cooler as the heart of a 925mb thermal trough axis advects into the area behind the front. Highs will only warm into 60s and lows will upper 40s and lower 50s.

LONG TERM
(Monday through Friday)
Issued at 307 AM CDT Sat Apr 20 2024

Monday and Tuesday will see a deep layer northwest flow regime dominate the Gulf South, and this will keep conditions clear and dry each day. With dry air in place, temperatures will see a larger diurnal range. Highs will warm into the lower 70s on Monday and the upper 70s on Tuesday, and lows will fall into the low to mid 40s north of I-10 and the low to mid 50s south of I-10 Monday night. Overall, have went with NBM 75th percentile values for highs and NBM 50th percentile values for overnight lows.

Wednesday will see a northern stream shortwave trough axis slide through the area, and weak attendant front will slip into the area and dissipate. This system will be moisture starved as PWATS remain around an inch, and do not expect to see much more than some passing cirrus as this system moves into the region.
Temperatures will continue to modify and highs are forecast to climb back into the lower 80s by Wednesday afternoon. The large diurnal range will also persist with temperatures cooling into the 50s Tuesday night. By Wednesday night, the return of onshore flow will support rising dewpoints, and expect to see lows only dip into the upper 50s and lower 60s. Boundary layer flow is expected to below 10 knots, and some radiation fog could develop over inland areas Wednesday night with this increase in low level humidity.

A strong longwave ridge will build over the area on Thursday and Friday, and the deep layer subsidence associated with this ridging will keep conditions dry both days. Temperatures will also continue to warm beneath this strong ridge with highs climbing back into the mid to upper 80s. Continued onshore flow will also keep pushing dewpoints up into the upper 50s and lower 60s, and this will result in lows only dropping into the 60s for Thursday night. However, boundary layer winds look to increase enough to keep fog development at bay on Thursday night.

AVIATION
(12Z TAFS)
Issued at 638 AM CDT Sat Apr 20 2024

IFR stratus has developed in the past hour at MCB in the wake of a frontal passage. These IFR ceilings will persist at MCB until around midday when daytime heating will mix out the boundary layer enough to support ceilings of 1500 to 2000 feet. The remainder of the terminals will see a mix of MVFR and VFR conditions as ceilings range from 2500 to 3500 feet today. Post-frontal scattered shower activity is also expected to become more pronounced after 18z and have included VCSH wording from 18z to 00z at MCB, HDC, ASD, BTR, and GPT. After 00z, the front will continue to move south and a broad area of IFR stratus and more persistent stratiform rainfall will overspread the area through the overnight hours and into early Sunday morning.

AVIATION
(06Z TAFS)
Issued at 307 AM CDT Sat Apr 20 2024

Have refreshed TAFs to back off onset of IFR CIGs at terminals with impacts most likely to be intermittent between 1000-1400 UTC.
Still can expect some drops to VIS to MVFR as well around sunrise. VCSH adjusted and -RA introduced closer to the end of the TAF period with low CIGs returning after 00 UTC. Winds will remain light and somewhat variable (initially south prevailing) as the front approaches the area.

MARINE
Issued at 307 AM CDT Sat Apr 20 2024

A cold front will push through the waters tonight into tomorrow, and northerly winds of 15 to 20 knots will develop after the front moves through. These winds will persist through Monday morning before easing as high pressure builds over the waters. Seas will respond to the stronger winds and could build to high as 5 feet over the open Gulf waters by Monday morning. As the high pulls to the east on Tuesday, a return to southeast winds of around 10 knots is expected. This southeasterly flow regime will persist through Thursday.

PRELIMINARY POINT TEMPS/POPS
MCB 78 54 62 44 / 50 70 60 10 BTR 84 61 66 48 / 30 50 50 10 ASD 84 62 68 48 / 30 50 70 20 MSY 83 66 68 55 / 20 50 70 20 GPT 81 63 69 50 / 30 40 70 20 PQL 81 63 69 48 / 30 40 70 20

LIX WATCHES/WARNINGS/ADVISORIES
LA...None.
GM...None.
MS...None.
GM...None.

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