What an event this is shaping up to be. This has to be one of the most interesting storms I've ever followed since it first showed up in the modeling. Already significant rainfall has occurred over much of the region, with a general 2-4 inches of rain racked up and isolated areas picking up about 5 inches! That definitely spells flooding for folks caught by the much heavier and persistent rain bands, which seems to have verified on the map I made previously. This system will continue to affect the Southeast over the next couple of days at least as rain will continue to fall but there are signs in the near future that the cut-off, once it gets going, will begin to wrap the colder air around itself quite rapidly, setting the stage for potential backside/underside snowfall. Anyone affected by the change of the airmass will likely experience a quick drop in temperatures, likely down into the 30s through the day tomorrow. This is associated with the process of dynamic cooling in combo with the already advancing colder airmass behind the front. It should eventually cause the moisture present at the time to fall completely as snow as we progress through the rest of Monday into the nighttime hours and for the day Tuesday.
With that said, my thoughts are that rain will still be present for a while through a part of Monday perhaps mixing with some snow before changing over to all snow across MS/AL/GA (particularly the northern and possibly central sections ) and TN, before the system begins its trek northeastward toward and along the Appalachians. It's still too early to tell exactly how much snow some will see out of this but I would have to guess that for anyone underneath the heaviest bands, a general 3-4" wouldn't be far-fetched with areas outside seeing 1-3" and if the nowcast modeling is under-doing the precipitation a little bit, then we can add a couple more inches to that. Ground temperatures are going to put up a fight against anything attempting to stick onto the surface but with heavy enough snowfall, grassy areas shouldn't be a problem so take that into consideration. There have been ULLs in the past that were so strong that despite warm ground temperatures, the snow was able to build which makes my confidence in any sort of accumulation low but the chance is there nonetheless. For the higher elevations across the mountains, I can easily see this standing a better chance and possibly cause some travel issues in the most likely areas. Some people continue to wonder the chances of some snowflakes just east of the Appalachians and right now that still looks quite low but that's not to say that I don't think our chances could improve a bit for maybe flurries across the western piedmont and along the foothills. Wouldn't get my hopes up on that but would be nice to see, even if it doesn't equate to accumulation.
One thing I should mention is that per the recent trend in the modeling, particularly the NAM, with such a significant system in store we also can't rule out that this becomes sort of a nasty severe weather event ahead in the warm sector due to increased potential for slightly more available instability and astounding shear. I don't think a big tornado threat is in store, though there could be a few isolated ones but it looks like the worst case scenario would be strong gusty winds associated with a linear-style convective mode. We'll have to keep watch and see how that plays out. Could be smaller or it may become a big deal of some sort.
Take care folks and hopefully some of you back west will see a good snow break out.
With that said, my thoughts are that rain will still be present for a while through a part of Monday perhaps mixing with some snow before changing over to all snow across MS/AL/GA (particularly the northern and possibly central sections ) and TN, before the system begins its trek northeastward toward and along the Appalachians. It's still too early to tell exactly how much snow some will see out of this but I would have to guess that for anyone underneath the heaviest bands, a general 3-4" wouldn't be far-fetched with areas outside seeing 1-3" and if the nowcast modeling is under-doing the precipitation a little bit, then we can add a couple more inches to that. Ground temperatures are going to put up a fight against anything attempting to stick onto the surface but with heavy enough snowfall, grassy areas shouldn't be a problem so take that into consideration. There have been ULLs in the past that were so strong that despite warm ground temperatures, the snow was able to build which makes my confidence in any sort of accumulation low but the chance is there nonetheless. For the higher elevations across the mountains, I can easily see this standing a better chance and possibly cause some travel issues in the most likely areas. Some people continue to wonder the chances of some snowflakes just east of the Appalachians and right now that still looks quite low but that's not to say that I don't think our chances could improve a bit for maybe flurries across the western piedmont and along the foothills. Wouldn't get my hopes up on that but would be nice to see, even if it doesn't equate to accumulation.
One thing I should mention is that per the recent trend in the modeling, particularly the NAM, with such a significant system in store we also can't rule out that this becomes sort of a nasty severe weather event ahead in the warm sector due to increased potential for slightly more available instability and astounding shear. I don't think a big tornado threat is in store, though there could be a few isolated ones but it looks like the worst case scenario would be strong gusty winds associated with a linear-style convective mode. We'll have to keep watch and see how that plays out. Could be smaller or it may become a big deal of some sort.
Take care folks and hopefully some of you back west will see a good snow break out.
very well written and great forecast
ReplyDeleteAndy Wood
Meteorologist - Greenville, SC
foxcarolina.com/weatherblog
Hi Reggie,
ReplyDeleteAgree with most of your post and would underscore the NE movement of the ULL that "may" keep most of the moisture west of our region (Piedmont/Foothills) of the Carolinas. Also, while the source region will be favorable for snow, the column of air below will be well above frz and it will take a lot of evap cooling to keep in snow anywhere below 2-3K'.
Flood threat? Certainly possible but with the low river and stream levels and the dry ground, I'll be surprised if this is the big event that so many over on Americanwx are touting, again, for our area. So, I'm expecting an underperforming system (as compared to what I'm reading in the majority) with maybe a period of snow at the tail end for areas outside of the high country.
It will be interesting to watch, that is for sure!
Oh, and duration....totally not seeing this lasting into Wednesday, in fact, expect to see a sunset late on Tuesday...there you have it...I'm way out on a limb as compared to modeling/forecasts/etc....right where I like it - lol!
ANONmet_LKJ
Andy and ANON: Thanks you two. Glad y'all took the time to read this. I did the best I could to attempt forecasting this thing (Yeah I know. It's a heck of a challenge with ULLs). Of course, we all know that it is rather difficult to pinpoint exactly who sees snow, when, and how much of it falls but I have some confidence that what I stated will play out. Plenty of time for those last-minute changes so I will be keeping watch on that for the duration of this event. As of this comment, winter weather advisories have already been put out across western TN, northern MS, and even back into parts of eastern AR. I would expect those to shift more eastward with time. Current radar shows the spin beginning to appear with precipitation filling back in back in MS. Can't wait to see how it evolves through the day today.
ReplyDelete