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New Years Storm System, Dec 30th - Jan 2nd


northpittweather

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MPX busted with their 2-4" call here today...dry slotted with temp still at 35...hopefully tomorrows storm will refresh the slushy snowpack around here.

Wow, even yesterday it was obvious there would be no snow, just rain and perhaps a little sleet. It could have been a sharp gradient that made it into your forecast with the grid system.

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If anyone wants a good example of how the potential energy in a strong low level baroclinic zone is worked, check the storm over the Northern Plains now. Pretty intense gradient and strong low level response with a low amplitude broad shortwave. Now, remember the superbombs the GFS had 192 hours out? Look at the second storm coming in 36 hours and the size of the upper disturbance. This first wave is a "sacrificial lamb", and if this storm came in one chunk, it would have been an epic storm since the amount of potential energy being converted by this first "sacrificial lamb" shortwave is significant. If that second wave came first, this would be a major winter storm, and if it all came in one chunk, historic. Non-linear growth doesn't add up in the 2 pieces.

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I've been surprised how fast our snow has melted. I thought we'd still have a few inches after tomorrow, but that won't happen. After the last snowstorm we had 10.5 inches of snow on the ground, but now my yard is down to about 2 inches and open areas are becoming bare. At this point I hope the rest of the dirty snow will melt so we can start over.

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crazy. there are 55-60dbz returns in there. heavy rain now here.

The NAM has some pretty beefy low level mass convergence near the inversion in response to the low amplitude wave.

post-999-0-38560600-1293752925.png

As typical with low amplitude waves over a moist baro zone, mid level height falls are rapid and induce cooling in the mid levels.

post-999-0-06720700-1293752974.png

Soundings suggest a layer of conditional instability above the inversion. Looks like the convection is lining up along the periphery of the low level mass response.

post-999-0-77252100-1293753084.png

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Impressive WV display for what seems like a run-of-the-mill low amplitude shortwave. Goes to show how amped that low level baro zone is. The models grossly underestimated how much the upper wave would amplify. This first wave is stealing some of the thunder from the second wave.

post-999-0-37922100-1293755080.jpg

Look at how poorly the GFS simulated the amplification of the S/W as it interacted with the low level baro zone. Oz GFS 24 hours into the forecast:

post-999-0-55311000-1293755239.png

Compare to 18Z today. Huge difference, the the much greater amplification of this wave is wreaking havoc in ND with the blizzard. The second storm was supposed to be the biggie, but now this first one is dominating.

post-999-0-39755200-1293755223.png

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so the 2nd wave probably won't be as strong as the current one? NWS was saying the 2nd was the strongest of the 2

That was the way it looked until this thing over-amplified big time. I didn't foresee this, I don't think anyone did, even with that amped low level baro zone. Everything is spiraling and feeding back to the system. Looks like 985 was its peak, still 5-6 hpa lower than the guidance suggested at 21Z.

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My outlook from earlier today on the winter event as well as some contributions from the other team members as well. Enjoy.

Note: May need to zoom in on the picture as I tried to make it as big as possible with a screen cap :)

post-822-0-82524700-1293764668.png

Who is this forecast for?

Also, I think the blizzard warnings are for the event now, not the second.

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Who is this forecast for?

Also, I think the blizzard warnings are for the event now, not the second.

Blizzard Watches have been posted for the Fri-Sat event across the northern Plains. Most of the current warnings are for the on-going event. Only blizzard warnings for Friday at this time are across WY/NE.

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Who is this forecast for?

Also, I think the blizzard warnings are for the event now, not the second.

The midwest, and I will have to re-examine, for the second event there are some areas with blizzard warnings, so I'll get back to you. Never really forecasted much for this area, did a lot of work on severe weather in the southern plains but am expanding out for a couple of reasons.

Correction: There are blizzard warnings for this storm in the warned areas, with blizzard watches in effect for the second storm. Thanks for bringing that to my attention. I asked another forecaster about it and he reported the warnings for the second storm. Will correct in the 1AM STA. Once again thanks.

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The midwest, and I will have to re-examine, for the second event there are some areas with blizzard warnings, so I'll get back to you. Never really forecasted much for this area, did a lot of work on severe weather in the southern plains but am expanding out for a couple of reasons.

Correction: There are blizzard warnings for this storm in the warned areas, with blizzard watches in effect for the second storm. Thanks for bringing that to my attention. I asked another forecaster about it and he reported the warnings for the second storm. Will correct in the 1AM STA. Once again thanks.

Yeah no problem. The blizzard warning went up late too, it was not expected to be this intense today. This first storm is over-achieving big time.

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Yeah no problem. The blizzard warning went up late too, it was not expected to be this intense today. This first storm is over-achieving big time.

Definitely, I was checking with some of our affiliate guys out there and they said it was really surprising to them what this first system was bringing. Interesting developments out there and makes me wonder what is going to occur out there with this second storm and its chances of overperforming.

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