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Weekend Storm Discussion Part II, 2/18-2/19


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00z GFS BUFKIT for BWI

120218/2100Z 69 16005KT 43.3F RAIN 0.012

120219/0000Z 72 15007KT 40.6F RAIN 0.031

120219/0300Z 75 14008KT 39.0F RAIN 0.016

120219/0600Z 78 09005KT 36.3F RAIN 0.150

120219/0900Z 81 07013KT 35.1F RAIN 0.138

120219/1200Z 84 04017KT 34.0F RASN 0.307

120219/1500Z 87 03015KT 34.0F RASN 0.319

120219/1800Z 90 36014KT 34.0F RASN 0.154

120219/2100Z 93 33013KT 34.3F RASN 0.079

120220/0000Z 96 33012KT 34.5F RAIN 0.020

06z GFS BUFKIT for BWI

120219/0600Z 72 20005KT 40.6F RAIN 0.016

120219/0900Z 75 02004KT 39.9F RAIN 0.106

120219/1200Z 78 03010KT 37.6F RAIN 0.106

120219/1500Z 81 02017KT 35.2F RAIN 0.161

120219/1800Z 84 01018KT 32.5F RASN 0.146

120219/2100Z 87 35014KT 32.0F SNOW 0.213

120220/0000Z 90 35014KT 30.4F SNOW 0.161

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00z GFS BUFKIT for BWI

120218/2100Z 69 16005KT 43.3F RAIN 0.012

120219/0000Z 72 15007KT 40.6F RAIN 0.031

120219/0300Z 75 14008KT 39.0F RAIN 0.016

120219/0600Z 78 09005KT 36.3F RAIN 0.150

120219/0900Z 81 07013KT 35.1F RAIN 0.138

120219/1200Z 84 04017KT 34.0F RASN 0.307

120219/1500Z 87 03015KT 34.0F RASN 0.319

120219/1800Z 90 36014KT 34.0F RASN 0.154

120219/2100Z 93 33013KT 34.3F RASN 0.079

120220/0000Z 96 33012KT 34.5F RAIN 0.020

06z GFS BUFKIT for BWI

120219/0600Z 72 20005KT 40.6F RAIN 0.016

120219/0900Z 75 02004KT 39.9F RAIN 0.106

120219/1200Z 78 03010KT 37.6F RAIN 0.106

120219/1500Z 81 02017KT 35.2F RAIN 0.161

120219/1800Z 84 01018KT 32.5F RASN 0.146

120219/2100Z 87 35014KT 32.0F SNOW 0.213

120220/0000Z 90 35014KT 30.4F SNOW 0.161

Really nice improvement on the 06Z GFS.

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00z GFS BUFKIT for BWI

120218/2100Z 69 16005KT 43.3F RAIN 0.012

120219/0000Z 72 15007KT 40.6F RAIN 0.031

120219/0300Z 75 14008KT 39.0F RAIN 0.016

120219/0600Z 78 09005KT 36.3F RAIN 0.150

120219/0900Z 81 07013KT 35.1F RAIN 0.138

120219/1200Z 84 04017KT 34.0F RASN 0.307

120219/1500Z 87 03015KT 34.0F RASN 0.319

120219/1800Z 90 36014KT 34.0F RASN 0.154

120219/2100Z 93 33013KT 34.3F RASN 0.079

120220/0000Z 96 33012KT 34.5F RAIN 0.020

06z GFS BUFKIT for BWI

120219/0600Z 72 20005KT 40.6F RAIN 0.016

120219/0900Z 75 02004KT 39.9F RAIN 0.106

120219/1200Z 78 03010KT 37.6F RAIN 0.106

120219/1500Z 81 02017KT 35.2F RAIN 0.161

120219/1800Z 84 01018KT 32.5F RASN 0.146

120219/2100Z 87 35014KT 32.0F SNOW 0.213

120220/0000Z 90 35014KT 30.4F SNOW 0.161

Similar to DCA so def an improvement

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To support your statement even more - yes, 06z is much better.

I don't understand the differences between how BUFKIT and that meteogram forecast precip type, but no way do I see sleet. Soundings for 6z and 12z Sunday morning are definitely, much to my dismay, rain soundings on the 6z GFS. Freezing level is ~875mb and surface temp is in the upper 30s verbatim.

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I don't understand the differences between how BUFKIT and that meteogram forecast precip type, but no way do I see sleet. Soundings for 6z and 12z Sunday morning are definitely, much to my dismay, rain soundings on the 6z GFS. Freezing level is ~875mb and surface temp is in the upper 30s verbatim.

I have no idea, I just post them ;)

Posting the meteogram was more for visual purpose than anything, not everyone may be able to read and understand a BUFKIT print out.

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I don't understand the differences between how BUFKIT and that meteogram forecast precip type, but no way do I see sleet.  Soundings for 6z and 12z Sunday morning are definitely, much to my dismay, rain soundings on the 6z GFS.  Freezing level is ~875mb and surface temp is in the upper 30s verbatim.

Seems with heavier precip rates wet bulbing would overcome BL issues, yea not seeing sleet that's for sure.

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Model question here.

It probably has happened before, but isn't it unusual for the EC to take such a big jump in one run? And also, is the seemingly more consistent look to all of the models due to better data from the northern stream? If the answer to that last one is yes, then wouldn't it be logical to think that the wildness of the solutions is probably over, and we'll gradually hone in on the real solution?

Thanks, Good luck.

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Seems with heavier precip rates wet bulbing would overcome BL issues, yea not seeing sleet that's for sure.

No sleet, but precip rate will certainly determine changeover time (or even if there's a changeover).

Just remember, we are still relatively far away from Sunday aftn. Some things can happen between now and then, so it's important just to remain objective.

Indeed. Despite the surprisingly good consensus on track that occurred with the overnight runs, I'd like to get a couple model cycles of consistency under our belt before we get down into the nitty-gritty of RA/SN lines and changeover times.

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I don't understand the differences between how BUFKIT and that meteogram forecast precip type, but no way do I see sleet. Soundings for 6z and 12z Sunday morning are definitely, much to my dismay, rain soundings on the 6z GFS. Freezing level is ~875mb and surface temp is in the upper 30s verbatim.

The 06z GFS verbatim has the switchover between 15z and 18z for all three airports. There is still 0.5-0.6" of precip after 15z, and 0.3-0.4" after 18z. You do have to wonder about the lower level temps on the GFS if the 850 low is tracking through southern Virginia.

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Model question here.

It probably has happened before, but isn't it unusual for the EC to take such a big jump in one run? And also, is the seemingly more consistent look to all of the models due to better data from the northern stream? If the answer to that last one is yes, then wouldn't it be logical to think that the wildness of the solutions is probably over, and we'll gradually hone in on the real solution?

Thanks, Good luck.

Yes it happens. Also, perception [regarding consistency, not skill] about the ECMWF is so different than the other models since they only distribute products twice/day (instead of 4x).

The more consistent look has as much to do with the lead time for the event (error growth in the models) than anything. Solutions always become clearer closer to the event.

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Model question here.

It probably has happened before, but isn't it unusual for the EC to take such a big jump in one run? And also, is the seemingly more consistent look to all of the models due to better data from the northern stream? If the answer to that last one is yes, then wouldn't it be logical to think that the wildness of the solutions is probably over, and we'll gradually hone in on the real solution?

Thanks, Good luck.

The large jumps can be a bit deceiving though. The evolution of the ns and ss vorts has been kinda subtle for the most part. Variations in strength and timing but they have been in the same general areas for a couple of runs now.

6z gfs is showing the ns out in front of the ss and this is nice to see. The earlier inland and amped up gfs solutions were just variations in the timing of the 3 areas of vorticity. It wasn't really the huge model swings that people made it out to be.

It's kinda cool (and scary) the all the models are converging on a near perfect interaction for us. I posted yesterday that I thought a stronger version of the euro ots would be our best chance for snow and zwyts semi agreed but said he is hoping for a more amped up and moisture laden system and so far it looks like his version is on the table.

We're really only one ingredient away from being squarly in the crosshairs of a significant event and that's temps. Kinda the story of the winter lately. If you look at the 6z gfs, the hp supplying us with our cold air is still only in the 1024 range. In a normal winter in mid Feb this would be sufficient but we just haven't been blessed with cold air on our side of the globe.

Surface flow leading up to the precip onset is steady from the nw on the 6z gfs. That's encouraging and precip onset is at night and that's going to help with marginal temps too.

oh man, why can't it be sat afternoon.....

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You do have to wonder about the lower level temps on the GFS if the 850 low is tracking through southern Virginia.

With the track of the low and a high to the NW, the ingredients are pretty classic for an all-snow event. But given how warm boundary layer temps have been in the last few "storms", even with plenty cold 850 temps and northerly flow, I don't think you can discount the idea the GFS has.

I was a bit skeptical of the idea that the lack of snowcover to our north was hurting our low-level temps that much in these storms, but I'm warming up to the idea in the last few days/week.

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The large jumps can be a bit deceiving though. The evolution of the ns and ss vorts has been kinda subtle for the most part. Variations in strength and timing but they have been in the same general areas for a couple of runs now.

6z gfs is showing the ns out in front of the ss and this is nice to see. The earlier inland and amped up gfs solutions were just variations in the timing of the 3 areas of vorticity. It wasn't really the huge model swings that people made it out to be.

Well said. I'll add that the ensembles have been showing the volatility/uncertainty. Certain evolutions/paradigms/regimes have larger error growth characteristics than others....just as certain regimes are ridiculously easy to forecast. This is a case where very small perturbations (initial condition differences, for example) can project onto rapidly growing modes (i.e. small error leads to large error) resulting in different looking forecasts (even with fairly short lead times).

People focus so much on the surface reflection and precipitation skewing the perception of consistency.

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With the track of the low and a high to the NW, the ingredients are pretty classic for an all-snow event. But given how warm boundary layer temps have been in the last few "storms", even with plenty cold 850 temps and northerly flow, I don't think you can discount the idea the GFS has.

I was a bit skeptical of the idea that the lack of snowcover to our north was hurting our low-level temps that much in these storms, but I'm warming up to the idea in the last few days/week.

Interesting analysis. So, it looks like a classic NE'r pummeling setup, but because everyone has had a warm/snowless winter, we get hosed? Kick us while we're down. I'm wondering how much of the confusion of the storm in the models is the high surface temps. Might be something they don't handle well. I'll admit to being someone who likes watching these wildly different predictions from models because it adds to the enterntainment factor in storm tracking.

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