weatherwiz Posted January 31, 2011 Share Posted January 31, 2011 Discussion: We may be changing calender months but the weather pattern is far from changing as yet another significant winter storm will be impacting the region beginning mid morning Tuesday and then lasting through the overnight hours of Wednesday into the early morning hours of Thursday, now this will be a two part storm, just like the last one so there will be a lull in precipitation. The first part of the storm is going to be all snow and for everyone, I don't think there is any question regarding this. This snow will be associated with the warm front and warm air advection. The warm front lifting northward will provide a great deal of isentropic lift. With increasing moisture and moisture advection occurring out ahead of the front we will see a period of moderate to heavy snowfall. While this snow will only be around for several hours it may pack a decent punch and drop light to moderate snowfall accumulations in just a short period of time. As of now it doesn't appear this first round will provide any significant snowfall accumulations anywhere but it could certainly drop several inches of snow across most places. How much snow that occurs during round one could have a significant impact on the total severity of the storm as round two could be very nasty. After part one ends we get a lull as the second part of the system is still located back to our SW. Unlike part one, part two is very complex and there are a ton of variables to dissect here. Unlike the past systems we have seen this winter this system is going to phase the northern and southern stream energies very early, well to our west, what this does is allows for cyclogenesis to occur well off to our west and for system strengthening to our west. Normally when we see this scenario we are looking at a "Lakes cutter" a storm that basically rides up from the Ohio Valley through the Great Lakes and into Canada...this means we end up in a warm solution and will either see all rain or a brief period of snow before changing over to sleet/rain. However, this go around there are several different features in place which is not going to allow for this to happen. One thing to note is off to our north/northwest we have a pretty strong area of high pressure. This high pressure will do some special things, it will help to force the system more to the southeast, meaning it won't cut as far west as this system wants to. Remember, the flow around the area of high pressure is a clockwise flow, so the high being to our northwest means our winds in the lower levels of the atmosphere are going to be more out of the north...this will allow for Arctic air to stay into the region...in essence the cold air will be locked in. The second thing to note is the Polar Vortex is displaced just far southeast enough in southeast Canada to where it will provide a decent deal of confluence, this acts like a brick wall in a sense so as the storm trying to cut to our west meets this it gets pushed off to the southeast. Since this will try to cut to our west a warm front (the same warm front that will be responsible for the snows with part one) will attempt to lift northward through the region, now there are basically warm fronts at all levels of the atmosphere, one just above the surface, another up around 925mb, another around 850mb, 700mb, and then 500mb...the winds aloft from 925mb to 500mb are going to be out of the south/southwest...and will be very strong, this will really help to push the low-level and mid-level warm fronts northward. The surface warm front, however, will have a VERY TOUGH time advancing northward and these reasons were highlighted above...high pressure to the northwest helping to lock in the low-level at the surface and just above...cold air is more dense than warm air so it's going to fight back the warm air. We also have solid snow cover across the region as well which will also help to keep the cold air locked in as well...it slows down the progression of the warm air at the surface. From 925-700mb though the warm air will be able to lift a bit further northward than it will at the surface, this will create an overrunning situation (the less dense warm air overriding the more dense colder air)...this will create the potential for sleet/freezing rain across a portion of the area. Right now the major question is how far north does this warm air get? It shouldn't get any further north than the Mass Pike area, this means area to the north of the Pike should stay all snow and this is where MAJOR snowfall accumulations are expected to occur. South of the Pike is a different story, this is where we could be looking at sleet and/or freezing rain. Right now this is an extremely difficult call. The potential does exist for a significant ice storm for portions of the interior south of the MA Pike...coastal areas should not have much of an issue with freezing rain as they would likely go over to plain rain. The areas that could be affected by significant icing may also see as much as 2-5'' of snow prior to this, if a significant icing event were to occur we could be looking at serious issues with regards to widespread power outages and tree damage. This could be a potentially high impact situation and will be closely monitored over the next few days. What makes this storm such high impact is the fact that there is a good 15-30'' of snow on the ground already across much of the region and many structural buildings still have lots of snow on the roofs and we have seen numerous structural collapses due to the weight of the snow, with the potential for more snow, which may be wet and heavy in locations and even ice this problem could further escalate. Anyone who has lots of snow on their roof should get it removed as quickly as possible. This is going to be an extremely challenging forecast, especially for the areas in question of sleet or freezing rain. If we see more in the way of sleet than serious issues may be avoided, however, if freezing rain is the main player we may see serious issues. Forecast: Snow begins in the mid morning hours of Tuesday and lasting through the late afternoon. Total snow accumulations should be in the 3-7'' range across the region. This snow should be on the fluffier side. After this ends (part one) we get a several hour lull in the action. Part two looks to begin anywhere from midnight to 3 AM and will probably start off as snow for everyone, however, it is quickly expected to change over to sleet and/or freezing rain across areas south of the MA Pike and all rain for coastal sections. Areas north of the Pike can expect as much as 8-16'' of total snowfall...some spots could see as much as 18''! South of the Pike a total of about 4-8'' of snow can be expected then the question becomes do we see major ice accumulations or not...this will have to be worked out over the next few days. Link to comment Share on other sites More sharing options...
ChrisM Posted January 31, 2011 Share Posted January 31, 2011 Discussion: We may be changing calender months but the weather pattern is far from changing as yet another significant winter storm will be impacting the region beginning mid morning Tuesday and then lasting through the overnight hours of Wednesday into the early morning hours of Thursday, now this will be a two part storm, just like the last one so there will be a lull in precipitation. nice map paul but I tihnk a lot of areas are moving away from the ice storm threat Link to comment Share on other sites More sharing options...
TalcottWx Posted January 31, 2011 Share Posted January 31, 2011 USED: 12z guidance (without euro), NWS BTV and BOX snowfall maps taken heavily into consideration, extrapolated from BOX + BTV to develop GYX CWA snowfall totals. PRELIMINARY THOUGHTS*****... I think there is a POTENTIAL for this much snow to fall Link to comment Share on other sites More sharing options...
weatherwiz Posted January 31, 2011 Author Share Posted January 31, 2011 nice map paul but I tihnk a lot of areas are moving away from the ice storm threat Thanks. This is going to be a tough call to make, sometimes in these setups the models won't pick up on it precisely until the very last minute, the 12z NAM did move away from it and would be more snow/sleet but the GFS still appears to hint at the potential for icing. Either way this storm is going to be very ugly, were probably going to be dealing with wet snow in CT and that is not good. Link to comment Share on other sites More sharing options...
weatherwiz Posted January 31, 2011 Author Share Posted January 31, 2011 Discussion/Forecast: As discussed last night a very power and highly potent winter storm will be impacting the region over the next few days and the storm will come in two waves. The first wave will be mainly snow, although it is quite possible snow some locations see a mixture of snow/sleet, this is a bit different than the previous thinking that precipitation would be all snow. While the first wave won't be nearly as potent as the second wave it will still pack a fairly strong punch and should dump a good 3-7'' of snowfall across much of the region. The first wave will begin very early tomorrow morning, a bit faster in timing than previously thought and will probably end sometime in the mid to late afternoon hours. Snowfall will be moderate to heavy at times and may accumulate fairly quickly. Once we finish with the first wave we will get a several hour window with no action as the second wave is still back to our southwest. The second wave begins in the early AM hours of Wednesday, possibly as early as 2-3 AM and conditions will quickly deteriorate. Everyone should start off as snow but then as warmer air works in aloft snow will begin to change to sleet and then freezing rain, first across the coastal areas then areas further inland...this is the complex portion of the forecast, trying to determine how far north this mixing line gets, it's possible this line gets as far north as the MA Pike, but it should not get any more north than this. Last night there were concerns about the potential for a significant icing event, today's computer models don't really show this as a high potential but some areas may still have to deal with some icing...it may be a small and rather broad area so this will have to be watched very closely. While the threat may have backed off some this threat is not off the table yet and we could still deal with the potential for a significant icing event...this threat will be heavily monitored over the next day. If a significant icing event would occur it could be quite paralyzing. Areas that look to remain all snow looked to get crushed as the potential exists for as much as 10-18'' of snowfall in these areas...this will likely be confined to areas just north of the MA Pike up into southern NH. Here there should not be any mixing issues at all and snowfall growth and ratios will be a bit better than they will be off to the south. For areas south of the MA Pike the snowfall accumulation forecast may be on the tricky side as the amount of sleet/freezing rain contamination could have a big impact on snowfall totals. With this said between the first wave and second wave a good 8-12'' of snowfall should occur, however, the potential does exist for some higher snowfall amounts in these areas, especially if things aloft continue to trend colder...this will have to be watched very closely as well. For the coastal areas mixing and a possible changeover to rain will significantly reduce snowfall totals here, only expecting about 3-7'' of snow here, with most of the snowfall accumulations here occurring from the first wave of the storm. Another issue will be the potential for strong winds, especially across coastal sections, winds could guts up to 40 mph with isolated gusts in the 50-55 mph range certainly possible as well. Inland areas could gust to 25-35 mph. This could create isolated pockets of tree damage and power outages...this is something that will have to be watched as well. This will be a HIGH impact storm as much of the region already has a good 20-30'' of snow on the ground and there are many structures that have a great deal of snow on their roofs. There have already been numerous structural collapses across the region do to the heavy weight of the snow and this issue may become worse with this upcoming storm, especially for those who fail to take care of the situation now. The potential for significant icing could certainly make issues much worse, especially with tree damage and power outages, not to mention the fact that it would further add weight to the snow. This is a very complex forecast which will hopefully be more fine tuned later tonight and tomorrow morning. Link to comment Share on other sites More sharing options...
vttaconics Posted February 1, 2011 Share Posted February 1, 2011 USED: 12z guidance (without euro), NWS BTV and BOX snowfall maps taken heavily into consideration, extrapolated from BOX + BTV to develop GYX CWA snowfall totals. PRELIMINARY THOUGHTS*****... I think there is a POTENTIAL for this much snow to fall Your map gives me goosebumps!!! LOL A wicked deformation band seems likely to set up over central VT and NH..... looks like a solid prediction to me.... Link to comment Share on other sites More sharing options...
Ryan Posted February 1, 2011 Share Posted February 1, 2011 Tuesday round #1: Wednesday-Thurs AM round #2: Didn't have time to put together a total totals map... but you can do the math Link to comment Share on other sites More sharing options...
ROOSTA Posted February 1, 2011 Share Posted February 1, 2011 Crude Link to comment Share on other sites More sharing options...
weatherwiz Posted February 1, 2011 Author Share Posted February 1, 2011 Forecast: Snow is already working towards the region as part one of the storm associated with warm air advection from a northward advancing warm front is closing in on the region. In fact snow will begin flying in just a matter of hours, first beginning in southwest and western CT. This first round looks to pack a decent punch as strong isentropic lift and increasing moisture will make for a period of moderate to heavy snowfall. Snowfall will begin accumulating rather quickly as well given the rates it will be coming down and the very cold ground. It looks like a good 4-7'' of snowfall will occur across the region with this first round, although some locations could end up with as much as 8-9''! It is also possible some locations mix with and/or change over to a mix of sleet and freezing rain, this is likely to be confined to southern CT though, although it's possible cities as far north as Hartford could change over towards the end of the first round. The first round should be over with by 6:00 to 7:00 PM. Round 1 snowfall totals will also have an impact on the total storm accumulations as round 2 brings in some questions, especially for areas south of the Mass pike. After a several hour lull in the action round two will likely begin during the overnight hours of Tuesday and early AM hours on Wednesday. Mainly everyone should begin as all snow, however, it's possible some spots in CT, especially down towards the coast start off as a mix of snow/sleet. Heavy precipitation will quickly overspread the region by mid morning. Basically areas south of the Mass Pike will see a mix and/or changeover to sleet and freezing rain. The big question here becomes how much freezing rain occurs? This might not totally be known until Wednesday morning. There still remains potential for a significant icing event across a good part of CT, possibly extending as far north as Springfield, MA. If this solution does occur and we see more than 0.50'' to 0.75'' of ice accretion along with several inches of accumulating snows from round 1 we could be looking at serious issues with downed tree limbs and widespread power outages. If, however, we see more in the way of sleet, then we will avoid serious problems. This is still a very complex call. The heaviest snowfall totals will occur from areas north of the Mass Pike into southern NH where as much as 12-18'' of snow will occur, however, isolated amounts of 20'' are certainly possible. (These totals also include snow from round 1). Areas along the coastal plain may eventually turn over to all rain, however, it's possible they see more in the way of sleet/freezing rain as well so this will have to be watched. There is also the threat for strong winds across the region, especially along the coastal plain. Winds could gust to as high as 35-45 mph with gusts up to 55 mph possible. This could further add to the potential for downed trees/limbs as well as power outages. There still remains high concern over weakened building structures due to the weight of the snow that has already accumulated on them. With more major snow accumulations expected this will further add to this issue. We've already seen numerous structural collapses due to the weight of the snow on roof tops. Hopefully people have taken the proper precautions to remove snowfall from their roofs. Round 2 should end late evening on Tuesday but snow sowers may be on and off through the remainder of the night Link to comment Share on other sites More sharing options...
TalcottWx Posted February 1, 2011 Share Posted February 1, 2011 Crude 27-30 awesome inches here Link to comment Share on other sites More sharing options...
weatherwiz Posted February 2, 2011 Author Share Posted February 2, 2011 Well part one of the storm has come to an end but not before dropping anywhere from about 4'' to as much as 8-9'' across the region with the highest snowfall totals occurring across portions of MA. Towards the end of round one we also saw many locations actually end as some light freezing drizzle, in fact some locations, especially in southwest CT have had a few tenths of an inch of ice accretion. This will set the stage for some potentially major issues tomorrow. We also saw numerous reports of roof collapses as the weight of the snow on top of buildings have heavily weakened some structures, as many as 7-8 reports of this happening occurred today and this situation will not get any better over the next several days. Part two of the storm is only several hours away, part two is expected to be much more intense than part one was and this has the potential to create some serious issues across a major chunk of the region. Part two is going to throw lots of weather at us as we will have to deal with snow, sleet, freezing rain, and even strong winds. The further north you go the better chance you have of seeing mainly snow...it appears this will be areas to the north of the Mass Pike...while some mixing is possible here the mixing is not expected to be bad enough to significantly cut down on snowfall accumulations from part two. Many of these areas this afternoon with part one received as much as 4-8'' of snow, this is already on top of the incredible snow depth that is already on the ground. This lead to some roof collapses across this region today and has probably lead to the weakening of several other structures, with as much as another 6-10'' of snow possible with part two this could lead to more significant issues with roof collapses. As you get closer to the Mass Pike the snow may actually start to become more wet and heavy...if this does occur this will heavily increases the potential for more roof collapses. This could become a very serious issue tomorrow. For areas south of the Mass Pike the forecast becomes a bit more complicated, it is pretty certain that snow will changeover to sleet and freezing rain but the questions are; How much snowfall occurs before the changeover? How long does the period of sleet last? How much freezing rain and accretion occurs? These are the major questions that we probably won't be able to answer until later on tonight unfortunately. Areas more towards southern CT may not even start as snow, they may begin as sleet or even freezing rain...now many locations here, especially in southwest CT have already seen a few tenths of an inch of ice, if they begin as freezing rain they are likely to stay all freezing rain...if this occurs than we will be looking at a major ice storm in this area and could potentially see some major issues with widespread power outages as well as downed tree limbs. The potential here exists for as much as 0.40'' to 0.60'' of ice accretion, although it's possible we could see some locations near 0.70'' of ice accretion. This situation will have to be heavily monitored. As you work more towards the northern part of the state precipitation may start off as all snow or a snow/sleet mix...it is here where the potential for an additional 1-3''...perhaps 4'' of snow is possible...now the issues with this is the snow would probably be fairly wet and heavy in nature. This area as well already has an incredible amount of snow on the ground and has issues with lots of snow on top of building structures, while there haven't been as many roof collapses as in the southern part of the state or in MA there have been a few, with the potential for a few inches of heavy, wet snow this could really escalate the issue across the northern part of the state. It's possible areas on the extreme coast change over to plain rain which would greatly reduce any major icing issues and problems here. The MAJOR question here is once the snow changes over does it go to sleet or freezing rain...or perhaps sleet then freezing rain? Latest indications seem to point towards the freezing rain side of things, depending on how much ice accretion occurs we could be looking at some major issues across northern parts of the state as well. Right now it appears that as much as 0.20 to 0.30'' of ice accretion could occur, however, it is still possible we could see totals of up to 0.50'' depending on how quickly the snow goes over. This could lead to some power outages as well as downed tree limbs. This will have to be very closely watched. Part two will also have the potential to produce strong winds across the region, especially along the coastal areas, winds could gust to 25-35 mph although gusts up to 40-50 mph are certainly possible. This could lead to areas of tree damage and power outages as well. Part two should begin just after midnight in western areas and last through the morning and into the mid to late afternoon hours. Due to the timing this will have a significant impact on morning and afternoon travel. Conditions are expected to be very bad. By tomorrow morning more will be known on the extent of the ice threat and which areas will be at most risk. As for the map below...keep in mind the snowfall totals ALSO INCLUDE part one...so for example, the 12-18'' swatch is not an additional 12-18'' but will be storm total for part one and part two. Link to comment Share on other sites More sharing options...
TalcottWx Posted February 2, 2011 Share Posted February 2, 2011 Epic fail.... overall self grade of D+... wish I hadn't jumped on the noyes weenie bandwagon LOL... I did this bad and it was similar to the NWS forecast maps in all CWA's... FML Link to comment Share on other sites More sharing options...
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