019 FXUS64 KLIX 020849 AFDLIX Area Forecast Discussion National Weather Service New Orleans LA 249 AM CST Sat Jan 2 2021 .SHORT TERM (Today through Monday Night)... On the weather maps this morning, a secondary weak frontal boundary has provided another reinforcing shot of cooler air at the surface, with surface winds all across the area switching from the SW to the NW overnight. This post-frontal air is very shallow according to model soundings early this morning - only at around 1500ft AGL before winds quickly back from the W to SW through the rest of the column to the tropopause. Taking a larger synoptic scale overview shows a secondary shortwave trough swinging across southern Texas, with troughing all the way down into the low- levels to our west helping to pump ongoing moisture in the mid to upper-levels on top of this post-frontal airmass. Observations this morning show a few layers of clouds, mainly in the 850mb to 700mb layer, and again in the 300 to 200mb layer along this progressive SW flow. It is looking like we will see partly to mostly cloudy skies today as the base of the trough at the mid/low levels approaches the area - helping to support enough downstream divergence and ascent to keep clouds around at times. RAP guidance for later this morning indicates building moisture advection in the low-levels, especially across coastal LA and MS that may lead to a few isolated showers or drizzle between 15Z and 21Z today. However, proximity soundings in this region illustrate that there will likely be enough dry air above the LCL to the base of the deeper moisture at and above 850MB to prevent a lot of this from reaching the ground, regardless of evaporative cooling processes at work. Blended guidance came in shy with PoP coverage and will keep this rolling. Although, cant rule out some light drizzle for coastal SE LA and/or eastern parts of the MS coast but chances will be low. Otherwise, temperatures today will struggle to warm with highs in the 50's and a few 60's. This trough quickly pulls to our northeast later tonight which will build in upper-level upstream convergence/surface high pressure to settle in along with clearing skies. Model soundings indicate rather strong radiational cooling/subsidence along with nearby surface high pressure and calm winds to tank temperatures all across the area. Fortunately, nothing excessively cold with temperatures likely ranging in the lower to mid 30's. Cant rule out a few areas touching freezing for an hour or two - especially for areas along and north of I-10/12 (and in traditionally colder drainage basins) but should refrain from seeing any freezing temperature issues - other than areas of frost daybreak Sunday. Guidance also suggests the potential for patchy fog along the Atchafalaya Basin and around BTR daybreak Sunday. Decided to back off on the extent and coverage wording from areas to patchy - as only some select VIS guidance hints at this potential but wanted to keep the mention there. Otherwise Sunday will be gorgeous with ample sunshine but a bit chilly with afternoon highs ranging around normal to slightly below normal. We warm up a bit more on Monday with highs in the mid to upper 60's but remain calm and dry with ample sunshine. A great way to start the week. KLG .LONG TERM (Tuesday through Friday Night)... High pressure will begin to shift eastward Tuesday night as an upper trough pushes a surface low and cold front into the plains states. Models generally agree a closed low will form in the base of the trough, though the depth of this low is still in question. Still some differences in the timing of the cold frontal passage through the local area as well. A blend continues to seem reasonable given the uncertainties at this lead time. Will mention there is considerable potential for a busted temperature forecast for Wednesday night into Thursday. Currently carrying a forecast in which the front does not come through until around daybreak Thursday, but if the front comes through earlier, temperatures could be several degrees cooler than forecast. Alternatively, if the front slows down further, highs on Thursday will need to be raised. 95/DM && .AVIATION... .Valid 06z Jan 02 through 12z Jan 03... Upper trough will move through the local area accompanied by passing clouds. The question is at what altitude any ceilings will be. Have included TEMPO groups at a few sites for MVFR or IFR cigs near daybreak due to shallow low level moisture, but am generally calling for prevailing VFR conditions otherwise. Should note that MVFR ceilings could very well spoil the forecast as the upper trough moves through between 12z and 18z, however. Will need to monitor trends and update accordingly if lower ceilings look to sneak into the local area. After 18z, trough axis shoves remaining low level moisture east of the local area and VFR conditions should prevail through the remainder of the period. 95/DM && .MARINE... A weak cold front has passed across the northern Gulf coast early this morning, helping to provide a reinforcing shot of cooler air and switching surface winds from the northwest today. Winds may be gusty at times - specifically west of the Mississippi Delta to around 10 to 15 knots, but will refrain from reaching advisory criteria. Additionally, this offshore flow will begin to build seas offshore the MS delta and to the west reaching 4 to 6 feet - with occasional 7 feet possible across offshore 20 to 60nm zones through tonight. Can't rule out some showers and a few storms east of the MS Delta later this morning and afternoon - with any of this activity exiting to the east around sunset today. High pressure will build in Sunday with winds diminishing along with seas becoming much more calm through early and the middle parts of next week. KLG && .PRELIMINARY POINT TEMPS/POPS... MCB 54 33 60 37 / 0 0 0 0 BTR 54 34 60 39 / 0 0 0 0 ASD 59 35 60 38 / 0 0 0 0 MSY 57 41 58 42 / 0 0 0 0 GPT 60 37 59 39 / 10 0 0 0 PQL 62 36 60 36 / 10 0 0 0 && .LIX WATCHES/WARNINGS/ADVISORIES... LA...None. GM...None. MS...None. GM...None. && $$