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044 FXUS64 KLIX 172115AFDLIXArea Forecast DiscussionNational Weather Service New Orleans LA315 PM CST Mon Feb 17 2025...New SHORT TERM, LONG TERM, MARINE....KEY MESSAGES...1 - Marginal threat of excessive rainfall and severe weather overnight Tuesday night into Wednesday morning. Widespread rain amounts of two inches or more are possible across the area, which could cause some runoff issues, especially in urban areas. Main severe weather concern would be hail near quarter size. 2 - A strong cold front will bring widespread freeze conditions to most of the area Wednesday night and again Thursday night. This is likely to include portions of the New Orleans metro area, with potential for hard freeze conditions across SW MS and portions of SE LA near and north of Interstate 12. Wind chill values in the teens and lower 20s are likely across much of the area both Wednesday night and Thursday night. Expectation is that Cold Weather Advisories will be necessary for just about the entire CWA both nights.&&.SHORT TERM...(This evening through Tuesday night)Issued at 300 PM CST Mon Feb 17 2025Upper flow is generally zonal across the southern half of the country this afternoon. At the surface, high pressure extended from the Canadian Prairie Provinces to the lower Mississippi RiverValley. Clear skies across the area this afternoon with temperatures generally in the mid and upper 50s. Tonight will remain mostly clear with surface winds graduallycoming around to the east. Temperatures may not be quite as coldas this morning, but won't rule out isolated readings nearfreezing, especially in the Pascagoula River drainage region inJackson County.Isentropic processes will bring a lowering cloud deck to the areaduring the daytime hours Tuesday, with light rain potentiallyreaching the surface prior to sunset Tuesday. With the barocliniczone likely remaining off the Louisiana coastline Tuesday and Tuesday night, a developing surface wave is likely to moveeastward along this zone toward the area Tuesday night. Precipitable water values are expected to increase to the 75th to 90th percentile climatologically (1.25 to 1.6 inches). With the warm, moist air getting advected over the cold airmass, elevated,embedded convection is expected to develop. At this time, it appears that any surface based convection is likely to remain offshore, with the possible exception of lower Plaquemines Parish.That leaves hail (up to an inch in diameter) as a potential concern. Widespread rain amounts of around 2 inches can beexpected from Tuesday evening into Wednesday morning, with a fewspot totals in excess of 3 inches. Could be some isolated runoffissues, especially in urban areas, but most areas have seen aninch or less of rain over the last couple weeks. At this time, aFlood Watch is not anticipated. High temperatures Tuesday are expected to be warmer than today'sreadings, but are somewhat dependent on how quickly the cloudsthicken and lower. A few hours difference in timing could be thedifference between highs in the upper 50s and highs in the mid 60s. Temperatures will drop off somewhat Tuesday evening asprecipitation onsets, before flattening out until after thepassage of the surface wave. Across southern portions of the areanear the baroclinic zone, temperatures could even rise a bit aftermidnight. &&.LONG TERM...(Wednesday through Sunday night)Issued at 300 PM CST Mon Feb 17 2025With the passage of the surface wave to the east of the area Wednesdaymorning, precipitation will end, and the arctic airmass willarrive. Little, if any, recovery in temperatures is expectedduring the daytime hours Wednesday, especially if clouds hold inall day as expected. It's entirely possible that the highs for the day could occur before most folks get out of bed Wednesday morning. Sub-freezing temperatures will be likely for most of thearea both Thursday and Friday mornings, with hard freezeconditions likely, especially Friday morning, for at least thenorthern half of the area. It won't be as cold as the January coldwave, but considering the warmth of the last couple weeks, it isgoing to be a shock to both vegetation, which had already startedgreening up, and to people. Entirely possible that record lowswill be threatened in some areas, especially Friday morning. Windchill values in the teens and 20s are likely Thursday and Friday mornings. Cold Weather Advisories for much of the area are almost certain to be issued in later forecast packages for those mornings. Sunshine should allow temperatures to moderate somewhat by Friday afternoon. Another shortwave moving near the Gulf Coast may spread some lightprecipitation into the area by Saturday afternoon or Saturdaynight, but temperatures should have moderated sufficiently toeliminate the potential for freezing or frozen precipitation. Temperature forecast is going to be a battle for the second halfof the week. As noted above, we may not see any recoveryWednesday. For Thursday and Friday, current numbers are a blendedsolution, somewhat toward the non-ECMWF solution, but can'tdiscount those, as there is quite a bit of agreement within theECMWF ensemble. By Sunday into early next week, temperatures willhave moderated to near or above normal.&&.AVIATION...(18Z TAFS)Issued at 1138 AM CST Mon Feb 17 2025VFR conditions expected through the forecast period. Expect to seea mid-level cloud deck move in by late morning Tuesday, withceilings lowering to perhaps FL050 by late afternoon. Could seesome -RA by late afternoon as well, but don't expect any flightrestrictions until after sunset Tuesday. &&.MARINE...Issued at 300 PM CST Mon Feb 17 2025Wind conditions have relaxed across the waters, but this is only abrief respite. Easterly winds are expected to increase during theday Tuesday, and Small Craft Exercise Caution headlines, andpossibly Small Craft Advisories, are likely to be needed by tomorrow afternoon across the western waters. Mariners should expect a prolonged period of hazardous conditionsacross most waters from Tuesday afternoon or Tuesday night into atleast Friday morning, before there's significant improvement inconditions. &&.PRELIMINARY POINT TEMPS/POPS...MCB 34 63 41 48 / 0 10 100 20 BTR 39 65 45 53 / 0 20 100 10 ASD 36 64 49 57 / 0 10 100 40 MSY 44 64 51 58 / 0 10 100 40 GPT 38 62 46 57 / 0 10 100 60 PQL 35 65 47 60 / 0 10 100 70 &&.LIX WATCHES/WARNINGS/ADVISORIES...LA...None.GM...None.MS...None.GM...None.&&$$SHORT TERM...RWLONG TERM....RWAVIATION...RWMARINE...RW
