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March 5 Snow Thread-Model Discussion ONLY


stormtracker

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LOL it does sound weenie but it's 3 models showing a similar situation. HRRR is at the end of the run showing that outcome and it takes on a look that seems to speed up. Noise id assume. The Lightning probs look to show that this thing will have dynamics in its favor. I'm game either way I just wish this was happening 6 hours earlier so I could ski a powder day.

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Yeah there's been a couple fill-ins east of the blue ridge in narrow bands today at different times to fizzle and rebuild. This has expanded north of the MD and is building south too. This should be out steady rain until it changes over Id imagine.

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rain changing to snow is almost never a favorable pattern for significant accumulations in the Middle Atlantic...except in March! That has been researched. If it's going to happen this would be the time to do it. But...those rates are gonna have to be intense to pile those widespread 6-10 inch amounts. If we lose the rates then the warning level snows will go with it.

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Second wave will have plenty of moisture to tap. Tapping from two oceans and a constant fetch. We are not dealing with a coastal low situation. We have enough moisture to build a rain forest.

The issue is the dense cold dry airmass that comes in and west to northwest flow is a down sloping flow...dry slotting or sharp gradients in precip. I think the nam and gfs are seeing this. PLUS...bands are very difficult to pinpoint even a few hours out let alone days!

We are likely to see intense narrow bands that dump very heavy rates in spots while steady light to moderate snow falls everywhere. Where those bands setup...only God knows!

 

Thanks for explaining. I figured the cold airmass would be the cause. But we need cold for snow!

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My personal forecast would be for a flip to Snow from 4:00am-9:00am NW/SE, DC should be changing over around 7-8am. Light to Moderate Snow through the rest of the day with Heavy Snow in the bands, this should last for 6-9hours. Total Snow in DC will be 2-5", Northern Maryland 4-7".

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My personal forecast would be for a flip to Snow from 4:00am-9:00am NW/SE, DC should be changing over around 7-8am. Light to Moderate Snow through the rest of the day with Heavy Snow in the bands, this should last for 6-9hours. Total Snow in DC will be 2-5", Northern Maryland 4-7".

Conservative. I respect that.

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rain changing to snow is almost never a favorable pattern for significant accumulations in the Middle Atlantic...except in March! That has been researched. If it's going to happen this would be the time to do it. But...those rates are gonna have to be intense to pile those widespread 6-10 inch amounts. If we lose the rates then the warning level snows will go with it.

Yeah I don't see much in terms of rates... I hope it pans out better than what the models are showing.

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Yeah I don't see much in terms of rates... I hope it pans out better than what the models are showing.

 

What models are you talking about.... the 18z NAM gives Washington Baltimore area 4 inches south to as much as 10 inches to the north.  All other models gives at least 4 inches.  Why so down?

 

The RAP has the northern counties up to at least 3 inches by 11 AM

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What models are you talking about.... the 18z NAM gives Washington Baltimore area 4 inches south to as much as 10 inches to the north. All other models gives at least 4 inches. Why so down?

I am still pissed off about the 6z gfs... Sent my entire day in to a tail spin. I think the ten inch totals will verify at around 6 or 7 and the 4 inch totals at like 2 or 3. There is no way we get max potential from qpf... So you gotta shave a little off. 3 or 4 inches really sucks compared to what the two globals were showing yesterday.

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I am still pissed off about the 6z gfs... Sent my entire day in to a tail spin. I think the ten inch totals will verify at around 6 or 7 and the 4 inch totals at like 2 or 3. There is no way we get max potential from qpf... So you gotta shave a little off. 3 or 4 inches really sucks compared to what the two globals were showing yesterday.

 

BWI averages 1.9 inches in March.  So 4 inches would be a major win.  Getting double digits in March is very hard to do.  March like last year comes once in a life time

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What I have for DC.  QPF is amount after the flip to snow.  As much of this as possible is verified, but I had to educated guesstimate for some.  

 

18z GFS - 0.38", 12-13z 

18z NAM - 0.54" - 14z 

18z4kNAM - 0.45" - 14z

18z RGEM - 0.45" - 13z

12z GGEM - 0.60" - 14z

12z EURO - 0.70" - 13z

12z UKMET - 0.60" - 14z

21z RAP - TBD - 14z

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What I have for DC.  QPF is amount after the flip to snow.  As much of this as possible is verified, but I had to educated guesstimate for some.  

 

18z GFS - 0.38", 12-13z 

18z NAM - 0.54" - 14z 

18z4kNAM - 0.45" - 14z

18z RGEM - 0.45" - 13z

12z GGEM - 0.60" - 14z

12z EURO - 0.70" - 13z

12z UKMET - 0.60" - 14z

21z RAP - TBD - 14z

 

Average:  ~.55

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What I have for DC. QPF is amount after the flip to snow. As much of this as possible is verified, but I had to educated guesstimate for some.

18z GFS - 0.38", 12-13z

18z NAM - 0.54" - 14z

18z4kNAM - 0.45" - 14z

18z RGEM - 0.45" - 13z

12z GGEM - 0.60" - 14z

12z EURO - 0.70" - 13z

12z UKMET - 0.60" - 14z

21z RAP - TBD - 14z

Even 0.4" is a good event here. Only concern would be how much of those qpf numbers would be good accumulating snow. Would think it could take an hour after changeover to start piling on all surface but I could be wrong. I guess a period of sleet would help in that regard more than a quick change to from rain to snow.

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What I have for DC.  QPF is amount after the flip to snow.  As much of this as possible is verified, but I had to educated guesstimate for some.  

 

18z GFS - 0.38", 12-13z 

18z NAM - 0.54" - 14z 

18z4kNAM - 0.45" - 14z

18z RGEM - 0.45" - 13z

12z GGEM - 0.60" - 14z

12z EURO - 0.70" - 13z

12z UKMET - 0.60" - 14z

21z RAP - TBD - 14z

If I may ask, when do we flip to IP...earlier the better it would seem

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Even 0.4" is a good event here. Only concern would be how much of those qpf numbers would be good accumulating snow. Would think it could take an hour after changeover to start piling on all surface but I could be wrong. I guess a period of sleet would help in that regard more than a quick change to from rain to snow.

 

I think we'll accumulate right away....It may take a while for the roads to capitulate but that doesnt really matter

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