Wed-Fri Storm Bust Analysis
Monday, March 11, 2013
So how about that widespread 15"+? Most meteorologists busted with this storm, and haven't heard the end of it. This storm matches closely with the April Fools storm of 1997 where there was a very similar setup (April 1, 1997 Analog). Many forecasters ended up changing their totals about three to four times but it wasn't just that. It was in the short amount of time they were changing their forecasts. Bust potential is imminent when you have meteorologists running back to the drawing board once the snow is already falling to change their totals. The best part? Meteorologists STILL busted after they adjusted their amounts. The NWS went from 3"-6" for Boston, to 6"-8", back down to 3"-6", then 8"-10", then finally 18"-24", all in a matter of a few hours. These ranges may not be exact, but you get the idea. You don't see this type of uncertainty very often which makes this whole event one for the ages.
So what the hell happened? Well as we all know, there was this large cut off low pressure a few hundred miles offshore. The distance this low was off the coast was not supposed to produce the significant snowfall amounts that it did. What made this all happen was another area of low pressure over New York. The energy of this low pressure moved east, wrapped around, and eventually coalesced (Fujiwhara Effect) with the cut-off low offshore, enhancing the easterly flow, which streamed all this extra moisture in off the ocean (mets like to call it "firehose"). There was also a TROWAL in place (trough of warm air aloft). This TROWAL occurs between 850-700 mb and provides nice lift of warmer, ocean air over the cooler air over land. These are usually associated to the north of an occluded front. That being said, it provides heavy bands of snowfall for some due to enhanced lift. If there wasn't such a prevalent block to the north and if the Fujiwara Effect didn't happen, the cut-off low would continue to scoot off to sea and the winds would not remain easterly for close to as long as they did; they would turn northerly faster. This second low basically "built a bridge" for strong easterly winds to remain so to speak, and with it, a boat load of moisture. It also "held onto" the cutoff low to prevent it from moving offshore too fast. Once all this moisture reached land, winds were NNE just due to the circulation of the low, which helped surface temps remain cool enough for accumulation in addition to the heavy snowfall rates that were occurring. What was special about this storm was that a change of 1 degree could've altered this whole thing for some areas.
As far as the models, the Euro wins once again. The GFS picked out the track of this storm first, but struggled mightily with the QPF amounts with this system. Below are the images of the Fujiwara/firehose event. The second low is the area of vorticity over Ontario/Upper Midwest.
So how about that widespread 15"+? Most meteorologists busted with this storm, and haven't heard the end of it. This storm matches closely with the April Fools storm of 1997 where there was a very similar setup (April 1, 1997 Analog). Many forecasters ended up changing their totals about three to four times but it wasn't just that. It was in the short amount of time they were changing their forecasts. Bust potential is imminent when you have meteorologists running back to the drawing board once the snow is already falling to change their totals. The best part? Meteorologists STILL busted after they adjusted their amounts. The NWS went from 3"-6" for Boston, to 6"-8", back down to 3"-6", then 8"-10", then finally 18"-24", all in a matter of a few hours. These ranges may not be exact, but you get the idea. You don't see this type of uncertainty very often which makes this whole event one for the ages.
So what the hell happened? Well as we all know, there was this large cut off low pressure a few hundred miles offshore. The distance this low was off the coast was not supposed to produce the significant snowfall amounts that it did. What made this all happen was another area of low pressure over New York. The energy of this low pressure moved east, wrapped around, and eventually coalesced (Fujiwhara Effect) with the cut-off low offshore, enhancing the easterly flow, which streamed all this extra moisture in off the ocean (mets like to call it "firehose"). There was also a TROWAL in place (trough of warm air aloft). This TROWAL occurs between 850-700 mb and provides nice lift of warmer, ocean air over the cooler air over land. These are usually associated to the north of an occluded front. That being said, it provides heavy bands of snowfall for some due to enhanced lift. If there wasn't such a prevalent block to the north and if the Fujiwara Effect didn't happen, the cut-off low would continue to scoot off to sea and the winds would not remain easterly for close to as long as they did; they would turn northerly faster. This second low basically "built a bridge" for strong easterly winds to remain so to speak, and with it, a boat load of moisture. It also "held onto" the cutoff low to prevent it from moving offshore too fast. Once all this moisture reached land, winds were NNE just due to the circulation of the low, which helped surface temps remain cool enough for accumulation in addition to the heavy snowfall rates that were occurring. What was special about this storm was that a change of 1 degree could've altered this whole thing for some areas.
As far as the models, the Euro wins once again. The GFS picked out the track of this storm first, but struggled mightily with the QPF amounts with this system. Below are the images of the Fujiwara/firehose event. The second low is the area of vorticity over Ontario/Upper Midwest.
I also want to note that I did not update my previous forecast (below) before model guidance changed.
Wed-Fri Storm UPDATE
Wednesday, March 6, 2013
So winter still does not want to end, despite meteorological spring beginning on March 1st, which is also my birthday (that's not weird or anything). This whole snow in March thing isn't anything new, especially since temperatures favorable for snowfall are a lot of times still in place. Currently, the atmospheric pattern for North America is still favorable for East Coast storms (at least through the middle of the month), however the deeper we get into March, rain events should become more likely.
About a week ago when models where picking out this storm, they all had it to the south of us. Beginning yesterday, the GFS hinted at a more northerly track, in addition with a swath of precipitation for much of the Northeast. Eventually, the rest of the models came on board and now we have another storm of concern. This storm is special because we have a large and strong blocking pattern to our north, which basically prevents this storm from just sliding on by us. For my forecast, I am primarily referring to the GFS solution, especially since it picked this storm out first, and has been very consistent.
This storm was initially supposed to be predominately a rain event for most eastern areas, however model guidance has cooled, meaning a widespread snow event for most other than the Cape and Islands. This is another long duration event, which means snow totals by the end of this are hard to determine, especially since ground temperatures (especially roads) may be slightly too warm to accommodate significant accumulation, but if the snow falls fast enough, that can all change.
FORECAST
Flakes may begin falling tomorrow afternoon, however I don't expect this thing to really "start" till tomorrow overnight, with this bulk of it falling all day Thursday into Thursday night. Precipitation should begin to taper off by Friday morning/early afternoon.
The main difficulty with this storm is where the rain/snow line will set up. Since 850 mb temps will be below freezing, I expect most to see snow out of this except for extreme coastal areas, in addition to the Cape/Islands, where surface temperatures may impede any significant accumulation so a mix/rain is more likely.
That being said...
Norfolk/Middlesex/Essex/SE Interior MA/Worcester/Western MA/RI/CT: 3"-7". For the CT River Valley folks you should see the bottom end of this range. For those in the Berkshires and higher elevations in CT there is a chance you could see 7", maybe even 8". I also wouldn't rule out NW RI and parts of N CT seeing the upper end of these values as well, considering wind directions are predominately from the N for this event, despite starting ENE, which locks the cold temps in place.
Southern NH: 3"-5".
Central NH: Coating-3".
Suffolk County/far exterior coasts (including CT/RI coasts)/Cape/Islands: You'll most likely see rain and a mix, which will really hurt your accumulation totals, but snow should be falling by the end of this, so I am going with nothing to 3".
Again, my biggest concern is that the snow may not fall fast enough to accumulate to reach the high end of my forecast totals, but when forecasting to the public, you always have to assume the worst possible scenario, which to me is reflected upon the totals I have forecasted. This will also be a very windy event, with sustained winds of 25-35 mph and gusts up to 50 mph (especially for coastal areas), so power outages are a possibility, since this will be a wet, heavy snow for most. Gusty winds should stick around till Saturday afternoon.
This forecast is really general, so if you want a specific forecast, feel free to ask.
So winter still does not want to end, despite meteorological spring beginning on March 1st, which is also my birthday (that's not weird or anything). This whole snow in March thing isn't anything new, especially since temperatures favorable for snowfall are a lot of times still in place. Currently, the atmospheric pattern for North America is still favorable for East Coast storms (at least through the middle of the month), however the deeper we get into March, rain events should become more likely.
About a week ago when models where picking out this storm, they all had it to the south of us. Beginning yesterday, the GFS hinted at a more northerly track, in addition with a swath of precipitation for much of the Northeast. Eventually, the rest of the models came on board and now we have another storm of concern. This storm is special because we have a large and strong blocking pattern to our north, which basically prevents this storm from just sliding on by us. For my forecast, I am primarily referring to the GFS solution, especially since it picked this storm out first, and has been very consistent.
This storm was initially supposed to be predominately a rain event for most eastern areas, however model guidance has cooled, meaning a widespread snow event for most other than the Cape and Islands. This is another long duration event, which means snow totals by the end of this are hard to determine, especially since ground temperatures (especially roads) may be slightly too warm to accommodate significant accumulation, but if the snow falls fast enough, that can all change.
FORECAST
Flakes may begin falling tomorrow afternoon, however I don't expect this thing to really "start" till tomorrow overnight, with this bulk of it falling all day Thursday into Thursday night. Precipitation should begin to taper off by Friday morning/early afternoon.
The main difficulty with this storm is where the rain/snow line will set up. Since 850 mb temps will be below freezing, I expect most to see snow out of this except for extreme coastal areas, in addition to the Cape/Islands, where surface temperatures may impede any significant accumulation so a mix/rain is more likely.
That being said...
Norfolk/Middlesex/Essex/SE Interior MA/Worcester/Western MA/RI/CT: 3"-7". For the CT River Valley folks you should see the bottom end of this range. For those in the Berkshires and higher elevations in CT there is a chance you could see 7", maybe even 8". I also wouldn't rule out NW RI and parts of N CT seeing the upper end of these values as well, considering wind directions are predominately from the N for this event, despite starting ENE, which locks the cold temps in place.
Southern NH: 3"-5".
Central NH: Coating-3".
Suffolk County/far exterior coasts (including CT/RI coasts)/Cape/Islands: You'll most likely see rain and a mix, which will really hurt your accumulation totals, but snow should be falling by the end of this, so I am going with nothing to 3".
Again, my biggest concern is that the snow may not fall fast enough to accumulate to reach the high end of my forecast totals, but when forecasting to the public, you always have to assume the worst possible scenario, which to me is reflected upon the totals I have forecasted. This will also be a very windy event, with sustained winds of 25-35 mph and gusts up to 50 mph (especially for coastal areas), so power outages are a possibility, since this will be a wet, heavy snow for most. Gusty winds should stick around till Saturday afternoon.
This forecast is really general, so if you want a specific forecast, feel free to ask.