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Early March threats - Mar 1st-8th Period


free_man

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A 96 hour forecast from an 18z run is definitely better than a 102 hour forecast from a 12z run. 

 

The way data is assimilated into the models now there's virtually no difference between 12z/00z and 06z/18z runs anymore.

 

It's not as bad as it used to be, I agree, but the 06z/18z GFS runs still perform below the 12/00z runs when it comes to verification.  This is not a bash on the 6/18z runs, but I still take them with a little less weight than the 12/00z runs.  I really am leaning on the Ensm right now and the Euro/GFS are pretty close imo on this one.

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A 96 hour forecast from an 18z run is definitely better than a 102 hour forecast from a 12z run. 

 

The way data is assimilated into the models now there's virtually no difference between 12z/00z and 06z/18z runs anymore.

 

Doesn't this get discussed literally every time someone/we analyze either a 6z or 18z run of any model?  lol.

 

Someone needs to pin something that says all model runs are created equally.

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Uh, that pretty much anything "shuts" this area down. People can't drive

an inch of rain, let alone an inch of snow around here. Not sure my post needed explanation, given the context.

meh, all big city traffic blows but Boston was fully functional within 72 hours after 25'' fell. Cant say the same for DC back in '10
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So would that imply that the 12z would still be more accurate than the 18z run 6 hours later for the same event?  And same with 00z and 6z? Or is that verifying for a fixed amount of time out in the future...ie 120 hours out from 12z and 120 hours out from 18z... vs 120hrs from 12z compared with 114hrs at 18z?

 

Not sure if what I'm saying makes sense...

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So would that imply that the 12z would still be more accurate than the 18z run 6 hours later for the same event?  And same with 00z and 6z? Or is that verifying for a fixed amount of time out in the future...ie 120 hours out from 12z and 120 hours out from 18z... vs 120hrs from 12z compared with 114hrs at 18z?

 

Not sure if what I'm saying makes sense...

i guess the scores bob posted sorta back up what you both said...if that's possible.....

 

the grades are so close that i don't really know if there is statistically a significant difference......and one can infer (pretty safely) that since they are pretty damn near close to the same....as 96 hr 18z would be at least as accurate as the 12z 102 hr.

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Dynamics will help under the upper level low for RIC/CHO/ORF. I think they have a chance for heavy accumulation especially if the low closes off a little later.

Dynamics can help it snow by cooling aloft and somewhat coolinh the surface, but do not help the fact that the BL is marginal and that peak rates occur during the day in central VA on 3/7.

I think NE VA has a chance for bigger accumulation, not downtown RIC

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Dynamics can help it snow by cooling aloft and somewhat coolinh the surface, but do not help the fact that the BL is marginal and that peak rates occur during the day in central VA on 3/7.

I think NE VA has a chance for bigger accumulation, not downtown RIC

 

Virginia has had plenty of big snowfalls in March. In fact RIC's latest accumulating snowfall was in mid-April if I remember correctly (1919? 1941?). I think the storm is gradually shifting north so that puts the threat more towards DC, but I wouldn't worry about it being March down there if the dynamics and track are well modeled. They'll do fine if they get that much precip with sub 0C 850s...it's not as if it hasn't snowed down there before in early March. 

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Virginia has had plenty of big snowfalls in March. In fact RIC's latest accumulating snowfall was in mid-April if I remember correctly (1919? 1941?). I think the storm is gradually shifting north so that puts the threat more towards DC, but I wouldn't worry about it being March down there if the dynamics and track are well modeled. They'll do fine if they get that much precip with sub 0C 850s...it's not as if it hasn't snowed down there before in early March.

Oh yeah I know. I'm not saying its going to rain, I really am trying to look at it from a perspective if I was down there forecasting for it. I would definitely temper my expectations with the factors on the table right now.

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Oh yeah I know. I'm not saying its going to rain, I really am trying to look at it from a perspective if I was down there forecasting for it. I would definitely temper my expectations with the factors on the table right now.

 

Some precipitation will definitely be wasted due to rain, but I think the heavier banding will be snow just inland from the coast, especially as it gets later in the day. I could see someone in north central VA receiving 12"+ if the storm holds as modeled. I think some of the suburbs outside of DC will do a little well, especially those in the 300-500' elevation band as you head outside the City. The threat may be fading for RIC south just because the general track of the storm is further north, not because of the boundary layer.

 

Meanwhile, the 0z GFS shows a solid snowstorm for snow-starved parts of the Midwest like Chicago. 

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I actually think there's a reasonable likelihood this storm brings some meaningful precipitation into SE areas as this will be a massive storm diameter-wise. Once the storm occludes and becomes vertically stacked, the precipitation shield will expand to the point where SE New England could be impacted by some of the outer bands, even if the low is well offshore. While I wouldn't expect a major event, it is something to keep an eye on. Precipitation type could also be an issue due to the east winds.

 

In addition, the easterly flow north of the storm could advect enough moisture inland that there could be some easterly upslope along the east side of the Berkshires. Again, this likely wouldn't be significant, but it could mean some accumulating snow for these spots.

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