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March 2- 4 Snowstorm Potential


NEG NAO

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Not sure why people are arguing about sun angles and melting for a storm that's 6 days away, but if you're going to argue, at least get the science right.  Yes, the sun angle is significantly higher in early March than in early January, so yes, significantly greater snow melting rates will occur during the day, especially between about 9 am and 3 pm, for the same surface temperature.  It's a pretty simple equation where accumulation rate = snowfall rate - snow melting rate and the melting rate is unquestionably greater now. 

 

However, at 28F, for example, that melting rate is probably about 1/4" per hour now vs. maybe 1/16" per hour in early January, which means that as long as we get a heavy enough snowfall rate, the snow will still accumulate - but it won't accumulate as well as it would in early January - that's a simple fact.  One point to keep in mind, however: once the snow starts accumulating on paved/dark surfaces, that snow layer will begin reflecting the incoming UV radiation, greatly reducing the snow melting rate from what it was prior to the snow covering up the darker/paved surfaces. 

 

Time to repost this for all the people who somehow seem to think sun angle doesn't matter.  It does.  As I said above, for the same given temperature, significantly more snow will melt during daylight hours (especially between 9 and 3) in early March than in early January and that will be exacerbated on paved/dark surfaces that absorb UV radiation (and convert it to IR/heat), until they are covered and then that factor won't matter, as the snow will reflect most of the UV.  Moderate to heavy snow will still accumulate - just not as much, since the melting rate is absolutely greater in March, due to the sun. Just look at today - we've had most of an inch melt in the ~2 hours since the snow stopped here (granted, that was mostly full sun and not indirect sunlight, but just illustrating the concept). 

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The weenie map on WxBell for the 12z GFS is pretty crazy. Just to give a general breakdown. The Harrisburg area is 30-36", Western NJ is 18-22", NYC proper is 10"+ with something in between 10 and 20" for NE NJ depending on your exact location. LHV area is also 12"+ with the Sullivan County area in the upper teens or lower 20". Same for Western, CT.

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Yeah a few GFS ensembles throw a weak overrunning disturbance and hold the ULL back, then blow it up, but not until Wednesday ish lol....Still a long way out guys a lot can change. Wouldn't be shocked if EURO throws something totally different at us.

 

Yanks, I know temps aren't important, but when you have LP over MD you can assume its warm which is what I was talking about

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Time to repost this for all the people who somehow seem to think sun angle doesn't matter. It does. As I said above, for the same given temperature, significantly more snow will melt during daylight hours (especially between 9 and 3) in early March than in early January and that will be exacerbated on paved/dark surfaces that absorb UV radiation (and convert it to IR/heat), until they are covered and then that factor won't matter, as the snow will reflect most of the UV. Moderate to heavy snow will still accumulate - just not as much, since the melting rate is absolutely greater in March, due to the sun. Just look at today - we've had most of an inch melt in the ~2 hours since the snow stopped here (granted, that was mostly full sun and not indirect sunlight, but just illustrating the concept).

What's the melting rate at 20 degrees? And no one is arguing it will melt after. Most in general think with temps progged by the model to be as low at the upper teens and low 20s that melting won't be too big of an issue.

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Yeah a few GFS ensembles throw a weak overrunning disturbance and hold the ULL back, then blow it up, but not until Wednesday ish lol....Still a long way out guys a lot can change. Wouldn't be shocked if EURO throws something totally different at us.

 

Yanks, I know temps aren't important, but when you have LP over MD you can assume its warm which is what I was talking about

I disagree respectfully, low pressure will be riding the stationary front, anything north of the track should be all snow, or close to it.

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Time to repost this for all the people who somehow seem to think sun angle doesn't matter.  It does.  As I said above, for the same given temperature, significantly more snow will melt during daylight hours (especially between 9 and 3) in early March than in early January and that will be exacerbated on paved/dark surfaces that absorb UV radiation (and convert it to IR/heat), until they are covered and then that factor won't matter, as the snow will reflect most of the UV.  Moderate to heavy snow will still accumulate - just not as much, since the melting rate is absolutely greater in March, due to the sun. Just look at today - we've had most of an inch melt in the ~2 hours since the snow stopped here (granted, that was mostly full sun and not indirect sunlight, but just illustrating the concept). 

Of course it plays some role especially when it comes to melting, that role is enhanced if temperatures are closer to freezing, but it's overstated far too often. The March superstorm had snow very far to the south. 

 

Models are getting into pretty good agreement with the overrunning, but the consolidated coastal is still the wildcard and that will have to be watched. It is only Wednesday so there's still a lot that can happen but there's a good chance we see a period of snow by late weekend to early next week. 

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The weenie map on WxBell for the 12z GFS is pretty crazy. Just to give a general breakdown. The Harrisburg area is 30-36", Western NJ is 18-22", NYC proper is 10"+ with something in between 10 and 20" for NE NJ depending on your exact location. LHV area is also 12"+ with the Sullivan County area in the upper teens or lower 20". Same for Western, CT.

Did eastern NJ cease to exist on this map?

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