weatherwiz Posted January 18, 2011 Share Posted January 18, 2011 Probably one of the worst calls ever and pretty bad but I tried...been going crazy over the past 7 hours typing something up and trying to sort things out myself without reading anyone else's thoughts which I can now do. I just like to do that so I can compare myself to what others think and see how much of an understanding I actually have on the situation. Discussion: Well folks the active string of weather continues as yet another significant winter storm is pegged to impact the region tomorrow. Unlike the past few storms, however, this one will feature more than just snow. We are looking at a mixture of sleet, freezing rain, and even regular plain old rain. It is this that will make this an extremely difficult forecast to make, it really doesn't get any harder than this. Despite the fact that we are within 12-15 hours from the onset of the confidence in this forecast is extremely low. This low confidence in this forecast is due to that fact there are tons of variables at play here and the slightest shift in storm track will have major implications on the outcome of the storm and how much snow falls, when some spots change to sleet/freezing rain and how much sleet/freezing rain occurs. Hopefully everything that needs to be covered here will be done so here and with as much detail and specifics as possible. I will say, as of right now I will hit this forecast on the harder side, just b/c of the significance of the potential impacts. While it may not pan out that way, it's probably best to prepare for the worst case scenario. An intensifying area of low pressure will be working up the coast through the overnight hours and tomorrow morning, it is this system that will be responsible for producing the nasty weather that will be occurring throughout the day tomorrow. The major question at this time is how close to our region does this area of low pressure track? With the past few systems they have at least tracked far enough to the east to where 99% of the region experienced all snow, with the exception of the Cape region. This system appears that it will track far enough to the west to where many of us will go from snow to sleet to freezing rain and to perhaps rain. The one thing that is pretty certain is just about everyone will see accumulating snowfall, with possibly the exception of eastern MA (this will be highlighted on one of the maps posted below). Areas that do receive accumulating snowfall with also have the potential to pick up possibly several inches of heavy, wet snow...interior southern New England (northern MA/NH may pick up as much as 8-15'' of snowfall as the cold air may stay locked in here for the duration of this event. The question regarding the snowfall portion of the storm is how long do certain locations see snowfall? At this point it's extremely difficult to pinpoint exactly how long everyone will stay all snow, this will really all depend on how long it takes for the warmer air that will be advecting aloft to work into the region, and how close the surface low tracks allowing for warmer air to work in at the surface. As what usually happens in the colder season warm air advection is usually quicker to occur aloft, usually several hundred feet to several thousand feet above the surface. This is b/c this time of year the water temperatures are usually on the chilly side, so as the surface wind comes off the water this slows down the northward progression of the warmer air towards the surface, meanwhile aloft the impact of the cooler water has less of an impact, thus it's a bit easier to bring in that warmer air. When trying to asses the advection of the warmer air there are certain things you want to look at, the track of the surface low as well as the areas of low pressure located at 925mb (~2500ft above sea-level), 850mb (5000ft above sea-level), 700mb (10,000ft above sea-level) and 500mb (18,000ft above sea-level). If these lows track to the west of your location or track pretty much over your location that places you in the warm sector of the storm as winds here are usually out of the south/southeast/east...this brings in warmer air. When dealing with this there are times where the low pressures at these levels will track in different directions. If the 700mb low is tracking to the west of your location this can often lead to your area being dry slotted at some point during this storm which can significantly decrease the amount of precipitation you see from the storm. If the 850/925mb lows track to your west or even over your location this can often lead to warm air advection occurring at these levels...if the surface low is tracking to your west this means the warm front will lift through your location and warmer air will work in at the surface. If these lows all track to your east and southeast then you will be locked in with cold throughout the entire storm and remain all snow. There are times where the surface low may track to your east and southeast while the 925/850mb lows track either over your location or to the west of your location...this is an instance where this may indeed occur. So what exactly does this mean? What happens during a case like this is you get warmer air to work in aloft (in this case between about 2000-6000ft) while at the surface the colder air gets locked in...this is called overrunning...the warm air is riding up and over the colder, more dense air at the surface. When this occurs you can either get sleet or freezing rain. Other things you want to pay attention to as well are if you have any snow cover (snow pack) over your region and if you have any sort of high pressure to your north. What the snow pack tends to do is help keep the colder air in place towards the surface a bit longer, remember snow is cold, and if you have alot of it it's going to radiate cold air and make it a bit more difficult for this warm air to work it smoothly. Having a high pressure to your north ensues that the wind direction will stay more out of the north, which means you can get colder air to drain down, making it even more difficult for the warmer air to work in, remember colder air is much more dense than warmer air so it's not going to give way to the warm air without a fight. In this case we do have a pretty solid snow pack throughout the region so this in a way should help us with keeping some colder air locked in a bit longer. While we don't have a high pressure to our north in this case there is one building in from the west, however, we also have an exiting area of high pressure to our east...it is this high pressure that could complicate things. Remember, the wind flow around an area of high pressure is clockwise, so if the high pressure is to your north and east that means the flow will be from the south and east...in our region that means a higher chance of warmer air working in. Something to note as well is some of the latest computer model runs show a stronger surface low working up the coast, with the area of high pressure to our east coupled with the stronger surface low what this does is create a stronger pressure gradient, when you have a stronger pressure gradient the response is strong winds, wind fields aloft are progged to be much stronger than previous model runs, what this means is we may see stronger and quicker warm air advection occur aloft which in turns means a quicker changeover from snow to sleet/freezing rain and then potentially rain if the surface temperature warms well above 32F. The challenging portion of this forecast here is assessing how much warm air advection takes places and how quickly it occurs. Right now we are dealing with a decent Arctic airmass in place over the region as temperatures are mainly in the teens and lower 20's...that is some solid cold. Temperatures aloft are also fairly cold as well although not relatively impressive cold...only around -10C to -12C at 925mb and -7C to -10C at 850mb. This is still pretty decent and will fight off the warm air advection at these levels as long as possible but eventually we'll see the warmer air work into these levels which is when the changeover from snow to sleet/freezing rain will occur. Given how we will see a surface low track to our south and east I think the forecast models are overdoing the level of warmth that will take place over the region, given this I think we'll see more in the way of sleet and freezing rain, rather than just plain rain. Thus, I think much of the region could be looking at the potential for some significant icing on top of potentially several inches of snowfall, if this were to occur we'd be looking at the potential for widespread power outages as we would see some tree/power line damage. Forecast: Precipitation should begin falling across the region anywhere from 5-8 AM and will start off as all snow. As much as 2'' to 14'' of snowfall will occur across the region. The lesser amounts of snowfall will occur out across eastern CT/RI/E MA with the highest snowfall accumulations occurring up across northern MA and southern NH. (Further details on this on snowfall map below). By 11 AM to 12:00 PM we will start seeing many locations begin the changeover from snow to sleet then freezing rain. This is when things may become rather troublesome as the potential will exist for some significant ice accumulations, I think northern CT and a good part of western and central MA and northern RI are all looking at this potential (Further details on this can be seen on map below). It is possible that we end up going from freezing rain to plain old rain, however, I think if this were to happen the most likely locations to see this would be southeast CT, central and southern RI and far eastern MA. The storm should begin winding down by 6-9 PM as the system works northeast and away from the region. Link to comment Share on other sites More sharing options...
NorEastermass128 Posted January 18, 2011 Share Posted January 18, 2011 Bullish...4-8" here. I'm thinking 1-3" -> IP/RN -> RN. Highs in the mid 30s...perhaps upper 30s. 40F+ on Wednesday? Link to comment Share on other sites More sharing options...
Confuzzled Posted January 18, 2011 Share Posted January 18, 2011 I think Quincy was right and we (CT) will see one heck of an ice storm tomorrow and very little rain except near the coast. I think the combination of early snowfall with extremely cold and extremely dry air has caused it to cool even more across the state the last few hours. With the exception of the immediate shoreline, several places have seen 2-4 degree temp drops....Its now 16 with a dusting and and light but steady snow falling (Waterbury) it was 18 here an hour ago. The temperature is probably a good 5 degrees above what NAM MOS runs had it at... GFS seems to be better on point right now... per BDL.... but It had DXR at 21 and 22 at 6z and 9z... while it was 18 at 06z and at 8z currently its still the same. It seems 08z temps in CT KBDL 16 KBDR 23 KDXR 18 KGON 24 KHFD 18 KHVN 22 KIJD 18 KMMK 18 KOXC 16 KSNC 19 Link to comment Share on other sites More sharing options...
FitzWx Posted January 18, 2011 Share Posted January 18, 2011 Nice discussion Wiz. You put a lot of thought and analysis in to it. I think it will be colder than model, thats based on historical ops. Thanks for your insight, hope works. Probably one of the worst calls ever and pretty bad but I tried...been going crazy over the past 7 hours typing something up and trying to sort things out myself without reading anyone else's thoughts which I can now do. I just like to do that so I can compare myself to what others think and see how much of an understanding I actually have on the situation. Discussion: Well folks the active string of weather continues as yet another significant winter storm is pegged to impact the region tomorrow. Unlike the past few storms, however, this one will feature more than just snow. We are looking at a mixture of sleet, freezing rain, and even regular plain old rain. It is this that will make this an extremely difficult forecast to make, it really doesn't get any harder than this. Despite the fact that we are within 12-15 hours from the onset of the confidence in this forecast is extremely low. This low confidence in this forecast is due to that fact there are tons of variables at play here and the slightest shift in storm track will have major implications on the outcome of the storm and how much snow falls, when some spots change to sleet/freezing rain and how much sleet/freezing rain occurs. Hopefully everything that needs to be covered here will be done so here and with as much detail and specifics as possible. I will say, as of right now I will hit this forecast on the harder side, just b/c of the significance of the potential impacts. While it may not pan out that way, it's probably best to prepare for the worst case scenario. An intensifying area of low pressure will be working up the coast through the overnight hours and tomorrow morning, it is this system that will be responsible for producing the nasty weather that will be occurring throughout the day tomorrow. The major question at this time is how close to our region does this area of low pressure track? With the past few systems they have at least tracked far enough to the east to where 99% of the region experienced all snow, with the exception of the Cape region. This system appears that it will track far enough to the west to where many of us will go from snow to sleet to freezing rain and to perhaps rain. The one thing that is pretty certain is just about everyone will see accumulating snowfall, with possibly the exception of eastern MA (this will be highlighted on one of the maps posted below). Areas that do receive accumulating snowfall with also have the potential to pick up possibly several inches of heavy, wet snow...interior southern New England (northern MA/NH may pick up as much as 8-15'' of snowfall as the cold air may stay locked in here for the duration of this event. The question regarding the snowfall portion of the storm is how long do certain locations see snowfall? At this point it's extremely difficult to pinpoint exactly how long everyone will stay all snow, this will really all depend on how long it takes for the warmer air that will be advecting aloft to work into the region, and how close the surface low tracks allowing for warmer air to work in at the surface. As what usually happens in the colder season warm air advection is usually quicker to occur aloft, usually several hundred feet to several thousand feet above the surface. This is b/c this time of year the water temperatures are usually on the chilly side, so as the surface wind comes off the water this slows down the northward progression of the warmer air towards the surface, meanwhile aloft the impact of the cooler water has less of an impact, thus it's a bit easier to bring in that warmer air. When trying to asses the advection of the warmer air there are certain things you want to look at, the track of the surface low as well as the areas of low pressure located at 925mb (~2500ft above sea-level), 850mb (5000ft above sea-level), 700mb (10,000ft above sea-level) and 500mb (18,000ft above sea-level). If these lows track to the west of your location or track pretty much over your location that places you in the warm sector of the storm as winds here are usually out of the south/southeast/east...this brings in warmer air. When dealing with this there are times where the low pressures at these levels will track in different directions. If the 700mb low is tracking to the west of your location this can often lead to your area being dry slotted at some point during this storm which can significantly decrease the amount of precipitation you see from the storm. If the 850/925mb lows track to your west or even over your location this can often lead to warm air advection occurring at these levels...if the surface low is tracking to your west this means the warm front will lift through your location and warmer air will work in at the surface. If these lows all track to your east and southeast then you will be locked in with cold throughout the entire storm and remain all snow. There are times where the surface low may track to your east and southeast while the 925/850mb lows track either over your location or to the west of your location...this is an instance where this may indeed occur. So what exactly does this mean? What happens during a case like this is you get warmer air to work in aloft (in this case between about 2000-6000ft) while at the surface the colder air gets locked in...this is called overrunning...the warm air is riding up and over the colder, more dense air at the surface. When this occurs you can either get sleet or freezing rain. Other things you want to pay attention to as well are if you have any snow cover (snow pack) over your region and if you have any sort of high pressure to your north. What the snow pack tends to do is help keep the colder air in place towards the surface a bit longer, remember snow is cold, and if you have alot of it it's going to radiate cold air and make it a bit more difficult for this warm air to work it smoothly. Having a high pressure to your north ensues that the wind direction will stay more out of the north, which means you can get colder air to drain down, making it even more difficult for the warmer air to work in, remember colder air is much more dense than warmer air so it's not going to give way to the warm air without a fight. In this case we do have a pretty solid snow pack throughout the region so this in a way should help us with keeping some colder air locked in a bit longer. While we don't have a high pressure to our north in this case there is one building in from the west, however, we also have an exiting area of high pressure to our east...it is this high pressure that could complicate things. Remember, the wind flow around an area of high pressure is clockwise, so if the high pressure is to your north and east that means the flow will be from the south and east...in our region that means a higher chance of warmer air working in. Something to note as well is some of the latest computer model runs show a stronger surface low working up the coast, with the area of high pressure to our east coupled with the stronger surface low what this does is create a stronger pressure gradient, when you have a stronger pressure gradient the response is strong winds, wind fields aloft are progged to be much stronger than previous model runs, what this means is we may see stronger and quicker warm air advection occur aloft which in turns means a quicker changeover from snow to sleet/freezing rain and then potentially rain if the surface temperature warms well above 32F. The challenging portion of this forecast here is assessing how much warm air advection takes places and how quickly it occurs. Right now we are dealing with a decent Arctic airmass in place over the region as temperatures are mainly in the teens and lower 20's...that is some solid cold. Temperatures aloft are also fairly cold as well although not relatively impressive cold...only around -10C to -12C at 925mb and -7C to -10C at 850mb. This is still pretty decent and will fight off the warm air advection at these levels as long as possible but eventually we'll see the warmer air work into these levels which is when the changeover from snow to sleet/freezing rain will occur. Given how we will see a surface low track to our south and east I think the forecast models are overdoing the level of warmth that will take place over the region, given this I think we'll see more in the way of sleet and freezing rain, rather than just plain rain. Thus, I think much of the region could be looking at the potential for some significant icing on top of potentially several inches of snowfall, if this were to occur we'd be looking at the potential for widespread power outages as we would see some tree/power line damage. Forecast: Precipitation should begin falling across the region anywhere from 5-8 AM and will start off as all snow. As much as 2'' to 14'' of snowfall will occur across the region. The lesser amounts of snowfall will occur out across eastern CT/RI/E MA with the highest snowfall accumulations occurring up across northern MA and southern NH. (Further details on this on snowfall map below). By 11 AM to 12:00 PM we will start seeing many locations begin the changeover from snow to sleet then freezing rain. This is when things may become rather troublesome as the potential will exist for some significant ice accumulations, I think northern CT and a good part of western and central MA and northern RI are all looking at this potential (Further details on this can be seen on map below). It is possible that we end up going from freezing rain to plain old rain, however, I think if this were to happen the most likely locations to see this would be southeast CT, central and southern RI and far eastern MA. The storm should begin winding down by 6-9 PM as the system works northeast and away from the region. Link to comment Share on other sites More sharing options...
H2Otown_WX Posted January 18, 2011 Share Posted January 18, 2011 I think Quincy was right and we (CT) will see one heck of an ice storm tomorrow and very little rain except near the coast. I think the combination of early snowfall with extremely cold and extremely dry air has caused it to cool even more across the state the last few hours. With the exception of the immediate shoreline, several places have seen 2-4 degree temp drops....Its now 16 with a dusting and and light but steady snow falling (Waterbury) it was 18 here an hour ago. The temperature is probably a good 5 degrees above what NAM MOS runs had it at... GFS seems to be better on point right now... per BDL.... but It had DXR at 21 and 22 at 6z and 9z... while it was 18 at 06z and at 8z currently its still the same. It seems 08z temps in CT KBDL 16 KBDR 23 KDXR 18 KGON 24 KHFD 18 KHVN 22 KIJD 18 KMMK 18 KOXC 16 KSNC 19 Somehow my weather station is saying 19.9 but Taft School is 14.9 and they're south of me. Link to comment Share on other sites More sharing options...
Confuzzled Posted January 18, 2011 Share Posted January 18, 2011 Somehow my weather station is saying 19.9 but Taft School is 14.9 and they're south of me. There is a hot spring under your house that always lowers your snow totals. That is why the PNS reports are always five inches greater than what you measure Link to comment Share on other sites More sharing options...
H2Otown_WX Posted January 18, 2011 Share Posted January 18, 2011 There is a hot spring under your house that always lowers your snow totals. That is why the PNS reports are always five inches greater than what you measure I think heat from my house is skewing my temp. I'll have to look into it tomorrow. Link to comment Share on other sites More sharing options...
weatherwiz Posted January 18, 2011 Author Share Posted January 18, 2011 Nice discussion Wiz. You put a lot of thought and analysis in to it. I think it will be colder than model, thats based on historical ops. Thanks for your insight, hope works. Thank you! Link to comment Share on other sites More sharing options...
weatherwiz Posted January 18, 2011 Author Share Posted January 18, 2011 El busto on my part as far as the icing goes. Link to comment Share on other sites More sharing options...
Damage In Tolland Posted January 18, 2011 Share Posted January 18, 2011 El busto on my part as far as the icing goes. I don't understand what you are talking about..there's gonna be moderate -heavy zr well into the nite..in fact you've got some over you now Link to comment Share on other sites More sharing options...
weatherwiz Posted January 18, 2011 Author Share Posted January 18, 2011 I don't understand what you are talking about..there's gonna be moderate -heavy zr well into the nite..in fact you've got some over you now Absolutely nothing going on here right now lol...I know the radar shows it but there is really nothing occurring. I think we will see some throughout the day but nothing that will cause any issues, except for driving of course. Link to comment Share on other sites More sharing options...
weatherwiz Posted January 18, 2011 Author Share Posted January 18, 2011 El busto on my part as far as the icing goes. I retract this statement. Link to comment Share on other sites More sharing options...
weatherMA Posted January 18, 2011 Share Posted January 18, 2011 Wiz your map varified pretty well...only thing to change would be to cut totals north. Your 8-14" could have been 6-10. Looks good though. Link to comment Share on other sites More sharing options...
ma blizzard Posted January 18, 2011 Share Posted January 18, 2011 nailed the heavier totals just E of ORH, nice work Link to comment Share on other sites More sharing options...
weatherwiz Posted January 18, 2011 Author Share Posted January 18, 2011 Thanks guys! Yeah I could have went lower with the totals up north and they did end up mixing/changing over. I am very happy with myself though., I was going through hell last night trying to compose this...worked on the discussion for nearly 7 hours lol. Link to comment Share on other sites More sharing options...
TalcottWx Posted January 19, 2011 Share Posted January 19, 2011 Map from two days ago has verified nicely. I think Sunday River will lolli for me. I got 12" in North Bridgton Link to comment Share on other sites More sharing options...
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