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277 FXUS64 KMOB 192229AFDMOBArea Forecast DiscussionNational Weather Service Mobile AL428 PM CST Sun Jan 19 2025...New NEAR TERM, SHORT TERM, LONG TERM, MARINE....NEAR TERM...(Now through Monday)Issued at 428 PM CST Sun Jan 19 2025A bitterly cold airmass locks in across the forecast area throughMonday. Surface high pressure continues to infiltrate the regionbringing with it an arctic airmass, and likely the coldest airmassof the year so far. Temperatures and wind chills are going to bethe biggest impacts through Monday with overnight lows tonightdipping into the upper teens and lower 20's for all of theforecast area. Winds remain slightly elevated through the night asthe pressure gradient is slow to relax, allowing for wind chillvalues to fall into the 8 to 15 degree range over much of theforecast area. Given this, have opted to upgrade the Cold WeatherAdvisory to an Extreme Cold Warning for dangerously cold wind chills. This magnitude of cold may result in frostbite on skin that endures a long exposure to the cold in addition to potentialfreezing/bursting of exposed pipes. Monday will continue to be very cold, with highs generally in the middle to upper 30's over the interior and upper 30's to lower 40's nearer the coast. MM/25&&.SHORT TERM...(Monday night through Wednesday night)Issued at 428 PM CST Sun Jan 19 2025...A significant winter storm is expected across the northern Gulf Coast, along with dangerously cold temperatures in place for multiple days...Synoptics... Longwave troughing over much of the CONUS at the start of the period will begin to lift to the northeast. An embedded shortwave will round the base of this longwave on Tuesday and will eject across our local area Tuesday night. At the surface, a massive high pressure system will help advect in a very cold, arctic airmass into the region. Additionally, a surface trough will develop over the western Gulf in association with the shortwave moving overhead. This trough will push very quickly to the east as it attempts to organize into a low pressure system. The trough/low will cross the Florida peninsula Tuesday night and move into the western Atlantic by Wednesday. Moisture will spread to the north of this surface trough, allowing for overrunning precip to occur across the area. With how cold the local area will be, winter storm conditions are becoming very likely across the area. Winter Storm Likely... A potentially significant winter storm is expected to affect areas along the northern Gulf Coast on Tuesday. At this point, the "dry scenario" is pretty much off the table, and with high probabilities suggesting that much of the area will see at least 1 to 2 inches of snow, the entire local area is now under a Winter Storm Watch from 6am Tuesday morning through 6am Wednesday morning. Although there are still some precip-type uncertainties along the coast, this will likely be an all-snow event for much of the local area. Along the coast, there may be just enough of a warm nose around the 850mb level to allow for some sleet pellets to be mixed in. Otherwise, looking at temperature profiles prior to the onset of precip, the dendritic growth zone looks to become fully saturated by around 09z-12z overtop a very dry 0-1km layer. Precip should initially start off as virga, or as very light flurries. Over the following couple hours, the dry lower levels will begin to moisten and cool (due to wet bulbing effects), likely bringing surface temperatures/dew points into the 20s. By this point, heavier snowfall rates will become realized and due to the colder temperatures at the surface, snow will start to accumulate. Looking at ensembles, the probability of accumulated snowfall greater than 3 inches continues to increase in comparison to previous days. Probabilities now stand at roughly 40 to 60 percent, which is why we are becoming increasingly concerned that this will be a significant event for the local area. If snow amounts over three inches actually occurred at KMOB, this would place us in the top 5 for historic snowfall amounts on record for the site. If three inches of snow occurs at KPNS, this would be actually be the highest accumulating event since the late 1800s! It should also be noted that probabilities have been pushed further to the south over the past couple days, with the best probabilities lining up around the I-10 corridor. Although there could still be some more minor fluctuations to where the heaviest snowfall will occur, these trends could lead to some major problems along our coastal counties. We urge residents and visitors to continue monitoring the forecast closely over the next few days and to begin preparing for this event. Dangerously Cold Temperatures... A long duration, anomalously cold airmass has already begun pushing into the local region. Temperatures will continue to tumble through the near term, with the coldest temperatures expected during this short term period. The high temperature forecast is still rather tricky when talking about ongoing winter precip on Tuesday and lingering snowpack on Wednesday. For Tuesday, have kept areas west of I-65 at or below freezing for high temperatures, given the earlier start to snowfall leading to wetbulb effects. I think that areas east of I-65 could briefly rise into the mid to upper 30s, but temperatures will likely quickly dive back into the 20s once precip starts. For Wednesday, the NBM was painting the area with highs in the low 40s. Although, yes, cloud cover will decrease allowing for plentiful sunshine, I'm very hesitant to go that warm due to the lingering snowpack across the area. In fact, looking at ensembles, the probability of getting above the freezing mark is only at around 55-65 percent for Wednesday. Therefore, I have lowered highs on Wednesday by about 4-7 degrees from the NBM output and am only forecasting highs around 34 to 38 degrees. These temperatures could even be a bit too warm especially if higher snow amounts are realized. The reason this is significant is that we may be below freezing for a longer period of time which could prolong the lingering effects from the Tuesday winter storm. Looking at lows, Monday night should drop into the 20s across the area, with mid to upper teens to the lower 20s in place for Tuesday and Wednesday nights. Factoring in winds, apparent temperatures (wind chills) may be in the single digits tothe lower teens across the area on Monday night and will almost definitely drop into the single digits for Tuesday night across the area. Therefore, an Extreme Cold Watch is now in effect starting 9PM Monday night through 10AM Wednesday morning. We continue to urge residents and visitors to make preparations to protect people, plants, pets, and pipes from this cold weather. /96&&.LONG TERM...(Thursday through Sunday)Issued at 428 PM CST Sun Jan 19 2025Upper troughing persists across the eastern CONUS through Friday in the wake of our winter weather event, with upper ridginggradually starting to build in Saturday into Sunday. Some residual impacts to area roads and bridges may be possible each morning through Friday associated with black ice as any melting of snow could refreeze on surfaces as overnight lows remain bitterly cold in the upper teens and lower 20's. Highs will only be topping out in the lower to middle 40's Thursday and Friday, which could be on the generous side depending on the magnitude of snow cover across the area. We warm up into the lower to middle 50's for highs Saturday and potentially even middle 60's by Sunday. Morning lows only finally make it above freezing by the time we get to Saturday night into Sunday morning with lows in thelower to middle 30's over the interior and upper 30's and lower 40's nearer the coast. Cold Weather Advisories may continue to beneeded Thursday night as overnight wind chills fall into themiddle teens areawide. MM/25&&.MARINE...Issued at 428 PM CST Sun Jan 19 2025A strong northwest flow continues through tonight and Monday in the wake of a strong cold front with a Small Craft Advisoryremaining in effect for all marine waters through late Mondaymorning. The strong northwest flow decreases and becomes northeast mid to late Monday. Another storm system will pass across the region on Tuesday allowing for strong offshore flow to continue through Wednesday morning. Confidence is increasing on the occurrence of gale force gusts Tuesday into Wednesday morning and a Gale Watch has been issued for the 20 to 60nm gulf waters. Another Small Craft Advisory goes into effect early Tuesday morning through Wednesday morning for the rest of the marine waters. MM/25&&.PRELIMINARY POINT TEMPS/POPS...Mobile 22 40 24 32 17 36 20 44 / 0 0 10 80 40 0 0 0 Pensacola 27 42 30 36 22 36 25 44 / 0 0 0 80 70 10 0 0 Destin 29 44 33 40 26 39 30 48 / 0 0 10 80 80 10 0 10 Evergreen 22 39 21 33 15 38 17 46 / 0 0 0 70 50 10 0 0 Waynesboro 19 37 20 31 13 37 17 45 / 0 0 10 70 20 0 0 0 Camden 20 37 20 31 13 36 18 42 / 0 0 0 70 30 0 0 0 Crestview 23 42 23 37 19 36 18 46 / 0 0 0 80 80 10 0 0 &&.MOB WATCHES/WARNINGS/ADVISORIES...AL...Extreme Cold Warning from 9 PM this evening to 11 AM CST Monday for ALZ051>060-261>266. Extreme Cold Watch from Monday evening through Wednesday morning for ALZ051>060-261>266. Winter Storm Watch from Tuesday morning through late Tuesday night for ALZ051>060-261>266.FL...Extreme Cold Warning from 9 PM this evening to 11 AM CST Monday for FLZ201>206. Extreme Cold Watch from Monday evening through Wednesday morning for FLZ201>206. Winter Storm Watch from Tuesday morning through late Tuesday night for FLZ201>206.MS...Extreme Cold Warning from 9 PM this evening to 11 AM CST Monday for MSZ067-075-076-078-079. Extreme Cold Watch from Monday evening through Wednesday morning for MSZ067-075-076-078-079. Winter Storm Watch from Tuesday morning through late Tuesday night for MSZ067-075-076-078-079.GM...Small Craft Advisory until noon CST Monday for GMZ630>636-650- 655-670-675.&&$$This product is also available on the web at:www.weather.gov/mob
