279 FXUS64 KLCH 180037 AFDLCH Area Forecast Discussion National Weather Service Lake Charles LA 637 PM CST Wed Jan 17 2024 ...New AVIATION... .SHORT TERM... (Tonight through Friday night) Issued at 340 PM CST Wed Jan 17 2024 Mid-afternoon sfc analysis shows high pressure centered over the ArkLaMiss and ridging swwd, with a mainly light srly low-level flow now in place across the region. Water vapor imagery a general wrly mid/upper-level flow at the moment with a few weak disturbances noted upstream. Satellite imagery shows mostly clear skies overhead although some WAA-induced lower clouds are noted approaching the coast, currently moving ashore over coastal Jefferson County in fact. Sfc obs show some the forecast area is getting some much needed warmer conditions after the two very cold days with temps generally in the lower 40s. Regional 88Ds are PPINE. As previously expected, our brief pattern change is underway with our sfc high now east of the area and an onshore low-level flow developing. With much of the area seeing reasonable radiating conditions initially tonight, will see temperatures drop quickly with sunset, with minimums occurring this evening, before rising later in the evening and through the overnight hours as the srly flow takes a firm grip. The biggest near term question with this package was what to do with the inherited Hard Freeze Watch over e-cntl LA as we have moved into the time window for action. Latest guidance indicated mins in the 24-28 range over the watched area, but the window for these readings looks pretty short...maybe an hour or two. When combined with the fact that these temps shouldn't have much of an additional impact after the past couple nights in the 10s or lower, it was decided to cancel the watch as opposed to upgrading to a warning. An SPS was issued to address the brief shot of criteria temps this evening. For Thursday, after an initial disturbance crosses the area tonight, a 2ry slightly stronger shortwave within the wrly flow aloft will move into the area, while also helping spin up a sfc low over the Red River Valley. Latest forecast soundings continue to indicate a general lack of deep moisture during the day when best heating/lift are expected...however, there may be sufficient moisture for a few showers to develop, primarily over the ern zones where moisture/lift will be best. With the increasing onshore flow, Thursday continues to look downright balmy with highs in the 60s (pushing 70 over portions of lower Acadiana). The precip will move out of the area during the late afternoon or early evening hours as the sfc low pulls the next cold front across the area. Thursday night mins look to be a little warmer with lows expected to be in the mid 30s to around 40. With the next round of post-frontal CAA set to commence Friday and sfc high pressure builds back over the region, the end of the work week looks to bring a return to sunny/cold/breezy conditions. Afternoon highs are progged to run in the upper 40s/lower 50s while another hard freeze looks likely for the nrn zones Friday night (possible I-10 swd). Overnight wind chills into Saturday morning are again likely to be in the 10-20 degree range for much of the forecast area. 25 && .LONG TERM... (Saturday through next Tuesday) Issued at 340 PM CST Wed Jan 17 2024 The long term period begins with another cold snap and hard freeze conditions across much of the area early Saturday morning. A strong nearly 1045 mb surface high will be centered over the central US, sprawling an arctic airmass across much of the US east of the Rockies. Despite mostly sunny skies, strong CAA will keep daytime highs in the 40s across the area which, when combined with brisk northerly winds, will feel about 10 degrees colder. The surface high will slide east through the weekend, but the cold air will stick around through at least Sunday, with overnight lows again ranging from the upper teens across central LA to the upper 20s/near 30 along coastal areas, and daytime highs in the middle to upper 40s as surface winds veer more easterly. A significant shift in the weather pattern is expected for the start of the workweek as a trough moves over the SW US. A series of disturbances emanating from the base of the trough will overspread the area late Sunday into Monday, inducing a surface trough across S TX and along the TX coast. Moisture advection will increase on strengthening low level flow across TX, with moisture deepening in response to SW flow aloft. PWATs are expected to rapidly climb Monday, from less than an inch to beyond the 90th percentile (peaking around 1.5 to 1.6 inches Monday night). Increasing ascent associated with the disturbances and abundant moisture will lead to increased rain chances across the area Monday, and rainfall could potentially become heavy at times. This will mark the beginning of what looks to be a prolonged period of unsettled weather and possibly heavy rainfall through much of the workweek as the lead shortwave ejects northeast across the plains and a second piece of energy digs into the base of the trough from Monday into Tuesday. Energy begins to consolidate enough to form a cutoff low within the trough, with little movement expected. This will produce multiple rounds of showers and storms through and beyond the end of the forecast period. Better details will emerge as the event approaches, such as timing individual rounds, ascertaining when and where the heaviest rain will occur, and also QPF amounts. WPC guidance with this forecast package suggests general rainfall totals between 3 and 6 inches could be common from Monday through Wednesday of next week, and this is supported by NBM probabilities between 30 and 50 percent for at least 3 inches of rain across portions of the area during this time. A marked warmup will also accompany this increasingly wet timeframe as surface winds become more southeasterly. By Tuesday into Wednesday, highs are expected to be in the middle 60s to around 70, with lows in the 50s. One additional note for marine interests, thanks to the recent cold outbreak, there will be an increased risk for marine fog over the coastal waters as the warmer airmass advects over the relatively chilly shelf waters. 24 && .AVIATION... (00Z TAFS) Issued at 515 PM CST Wed Jan 17 2024 High pressure has moved to the east resulting in southerly winds across the area. This southerly fetch will soon be the catalyst to bring on deep moisture overnight, and with it, lower cloud ceilings/fog. Southwest terminals are already seeing this take place with periods of overcast skies around 2500 feet. Expect this low, MVFR cloud deck to spread northeast over the next several hours. The greatest return of moisture will take place after 06Z, and with it, expect even lower cloud ceilings and patchy ground fog area wide. Patchy fog of 2 to 5 SM and ceilings between 500 and 1000 feet can be expected from 09Z to around 18 to 20Z when some VIS/CIG improvement can take place in the afternoon. Winds will prevail from the southeast for much of the overnight period with a turn to the southwest after 12Z tomorrow when high pressure continues its trek eastward. 11/Calhoun && .MARINE... Issued at 340 PM CST Wed Jan 17 2024 The CWF looks to remain headline-free until probably late Thursday night when strong offshore flow develops behind the next passing cold front...at this time, expecting just SCA conditions, which look to last into Saturday afternoon before diminishing with the approach of high pressure. 25 && .PRELIMINARY POINT TEMPS/POPS... AEX 24 63 32 48 / 0 10 0 0 LCH 33 65 39 52 / 10 10 0 0 LFT 33 68 40 51 / 0 20 0 0 BPT 38 66 39 55 / 10 10 0 0 && .LCH WATCHES/WARNINGS/ADVISORIES... LA...None. TX...None. GM...None. && $$ SHORT TERM...25 LONG TERM....24 AVIATION...11