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February 8-12 model discussion


Rankin5150

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18Z gfs is not far from bringing SAV/CHS a rare snowfall due to deep supression. However, it weakens too much and gives them no more than .05" qpf with only borderline 0C 850's. That's not going to quite do the trick. However, perhaps that means that a deeply supressed system is back on the table of possibilities? Longterm (300 year) climo says that 2/8-15 is by far the peak for 2"+ snowfalls in SAV/CHS.

I think it is trying to sus out blocking that is coming. But...it may have been eating the mushrooms again :)

I'm going with the former though, especially after that great snow it was giving along the coast some runs ago. T

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Hi everyone! I'm new here to AmericanWX. Been on AccuWeather for a couple months and now decided to sign up here too. Anyway, the last couple of runs of the GFS are pretty interesting to say the least! :P

Hi, welcome to the forum. I'm new here too !!

Hey guys while we get off topic sometimes there is a check in thread that is pinned on the main sub forum. We try to at least keep this to the models and the storm itself. Welcome all the same though scooter.gif

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The gfs has a nagging tendency to over suppress features in the long range. When the gfs has a concrete shortwave, but does not amplify it, yet the ECWMF, GGEM, and UKMET have a much stronger feature, there is a high likelihood that its out to lunch.

In fact I'm still worried more that this system tries to cut too far north rather than suppression at this time, so the longer the gfs shows this really far south solution, the less time it has to trend all the way back into an Apps or Lakes cutter.

This. I agree. I'm not getting excited about this one for awhile. Doesn't mean there isn't potential, though. Obviously, I'm pulling for my backyard. I wouldn't be surprised if this took a run up the TN Valley in E TN.

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Anyone have any ideas on how we could make sure it doesn't start to snow in the Raleigh area until after 8 pm on Thursday? I'll be in Phoenix next week, and I'll be home by that time. Thanks!

Well we could all go outside on wednesday and start blowing towards the west for a couple hours as hard as we can lol. honestly though storms seems to end up slower than modeled until about 18-24 until the event. Then it creeps in quicker from there. So who knows, you might be okay by 8pm.

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This. I agree. I'm not getting excited about this one for awhile. Doesn't mean there isn't potential, though. Obviously, I'm pulling for my backyard. I wouldn't be surprised if this took a run up the TN Valley in E TN.

Not going to get excited here either. Especially with this forecast from RAL.

Thursday: A chance of rain and snow. Partly sunny, with a high near 40. Chance of precipitation is 40%.

Thursday Night: A chance of rain. Partly cloudy, with a low around 16. Chance of precipitation is 40%.

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Well we could all go outside on wednesday and start blowing towards the west for a couple hours as hard as we can lol. honestly though storms seems to end up slower than modeled until about 18-24 until the event. Then it creeps in quicker from there. So who knows, you might be okay by 8pm.

Hey, every little bit helps. :). I'm hoping the seasonal trend holds of systems coming in a bit later than progged. If not, I might see about a red eye Wednesday night.

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The new NAM is looking much stronger on the Southeast/TN Valley trough by 72 hours. Probably good for bombing out the low off New England later on next week, in addition to TN/NC mountain snow possibly as it passes by. The other models weren't quite this strong, but were trending stronger with it, so it too is something to watch mainly in higher elevations I think.

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The new NAM is looking much stronger on the Southeast/TN Valley trough by 72 hours. Probably good for bombing out the low off New England later on next week, in addition to TN/NC mountain snow possibly as it passes by. The other models weren't quite this strong, but were trending stronger with it, so it too is something to watch mainly in higher elevations I think.

Am I wrong with starting to feel that the Piedmont of the Carolnas may be looking at some snow or wintry precip Monday?

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Don't really want to extrapolate the 0z Nam. But at hour 84.. its a bit weaker with the leading storm verses its 18z counterpart. And the storm to be is digging pretty far west ... and the surface reflection is a good 50 miles further north at hour 84 compared to the 90 hour 18z gfs run. Would use the assumption that it would be north and west of the gfs run. How much so is not known to do the unknown features of how the leading storm will bomb out once near Greenland... and how the northern stream will interact with the energy coming out of the west.

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Don't really want to extrapolate the 0z Nam. But at hour 84.. its a bit weaker with the leading storm verses its 18z counterpart. And the storm to be is digging pretty far west ... and the surface reflection is a good 50 miles further north at hour 84 compared to the 90 hour 18z gfs run. Would use the assumption that it would be north and west of the gfs run. How much so is not known to do the unknown features of how the leading storm will bomb out once near Greenland... and how the northern stream will interact with the energy coming out of the west.

Looking at the orientation of the northern stream coming down through eastern Alberta compared to the GFS, I would argue that there would be less separation between the two features compared to what the GFS showed (northern and southern as t is stepped). Granted, this is dangerous territory, NAM outside of its useful range and extrapolating on that nonetheless, but the isohypses are almost oriented N-S on the NAM, compared to NW-SE on the GFS, which would allow the second piece to dive farther south than what the Global showed. Also, the NAM is less robust with what should be a maturing cyclone south of the Canadian Maritimes, and given the model agreement on such deepening, not really on the same page in that regard, despite what looks like an extremely potent negatively tilted trough coming through the SE at 72hrs.

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Looking at the orientation of the northern stream coming down through western Alberta compared to the GFS, I would argue that there would be less separation between the two features compared to what the GFS showed (northern and southern as t is stepped). Granted, this is dangerous territory, NAM outside of its useful range and extrapolating on that nonetheless, but the isohypses are almost oriented N-S on the NAM, compared to NW-SE on the GFS, which would allow the second piece to dive farther south than what the Global showed. Also, the NAM is less robust with what should be a maturing cyclone south of the Canadian Maritimes, and given the model agreement on such deepening, not really on the same page in that regard.

Agreed on all points there.

Extrapolating from hat time frame on a mesoscale model at the point of its least usefulness...is very gusty and risky to do. The best thing one can do is compare the end run at that time and compare it to other models at that time and how those models then develop the features. Nam is handling the storm on the 8th differently than the global models were doing during the 12z cycle. Will have to wait for other guidance to complete their 0z runs to see if the 0z nam has any truth behinds its depiction at the end of its run.

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One thing I notice in looking at the Euro maps from this morning is that we are going to have more cold air to work with this time around compared to the 1/24 shipwreck. It's all going to come down to the 850mb track. That low will be tracking SW to NE. If you are a smidge NW of that track, you should be good to go for snow. There will be a sharp gradient of increasing amounts of cold air to the NW of that track.

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Agreed on all points there.

Extrapolating from hat time frame on a mesoscale model at the point of its least usefulness...is very gusty and risky to do. The best thing one can do is compare the end run at that time and compare it to other models at that time and how those models then develop the features. Nam is handling the storm on the 8th differently than the global models were doing during the 12z cycle. Will have to wait for other guidance to complete their 0z runs to see if the 0z nam has any truth behinds its depiction at the end of its run.

typo, should have been eastern Alberta, fixed, but it is the NAM at 84hrs, not like it really matters... :arrowhead: What strikes me as an outlier with this run is the first storm south of Nova Scotia, 1004mb centered over ME at 84 hrs compared to the 12z GFS which was 980 and well to the east of there. The Euro was a little slower than the GFS, but still depicted 970-something crashing into Nova Scotia. So in that regard, this run is an outlier and given the higher resolution mesoscale models weaknesses as time is stepped, the tip is towards to the globals at this range. The trough is mature coming through the SE at 72 hrs, but at 78 the energy kind of splits over the MA, likely a result on enhanced resolution being a double edged sword, good in the short term, but sucks at resolving the overall feature in the medium range.

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