Jump to content

OceanStWx

Meteorologist
  • Posts

    19,778
  • Joined

  • Last visited

Everything posted by OceanStWx

  1. Flow looks pretty favorable for NH. Good moisture, a moderate (3-5”) upslope event seems like a good forecast.
  2. Well the best WAA push will likely shoot through SNE, like inside 95. This becomes a bit of a pivoting band (I would pin it somewhere between 95 and 495), but is moving so quickly that lollis around 10” sounds about right.
  3. That’s the key, where the best snow growth is. And it’s usually just above 700 mb, which is why we want the best fgen forcing there. It all depends on the type of band. A WAA forced laterally translating band will sweep across the region with fairly uniform totals, because screw zones will move with the band. But a lateral quasi stationary band (like the last event) has the potential for subsidence to really screw the cold side of the heaviest lift.
  4. That screams something about initialization affecting the runs, if it truly is a 00/12z 06/18z tango. Balloon data is the primary difference that I know of.
  5. Clicking around some GFS soundings there are decent lapse rates over the interior just above the DGZ, even absent a MAUL. It would take much to really make the most of that.
  6. We're right on track for another bump or two NW followed by the messenger shuffle late to leave us right about where we are now. I see that poking in from RI.
  7. Taking a look at the forecast soundings the snow growth zone is rather low in the atmosphere. I don't think that changes substantially even with a further north track. So if your above H7 lift is good it's actually not in the heart of the DGZ like it normally is.
  8. It's nice to see what you, Bob, and Dave think. Kind of like forecast consensus. Not going to hurt my waistline any. We legal. To me it seems like the NAM has spaced things out a little better as the lead shortwave exits sooner and the trailing one hangs back just a bit.
  9. It's pretty well sampled at this point, or at least won't be better sampled. But the more it digs tonight the better these runs should get.
  10. Yeah, there were some late closures there that were congrats Nova Scotia, but if we can get that going between MTP and CHH it becomes a rosier picture.
  11. Oh we know there's a bias keeping the QPF too close to the low center for one. But even the 12z GFS has a decent banding signal from central LI through BOS despite what it's QPF/snow output shows.
  12. As an example, here is February 1 of last winter. Northern NJ is showing an EFI around 1, meaning every EPS member was more extreme than the model climate. And with a SOT value of 2, the top 10% of EPS members were also quite extreme. And well...
  13. There's some good news I guess. Based on the 00z EPS, the extreme forecast index is okay for the AEMATT crowd. This index essentially shows how unusual the EPS forecast is based on the last 20 years of the model climate in the 5 weeks centered on the date (the climate built by many model runs, not state of the climate according to the model). Values between 0.5 and 0.8 are unusual, above 0.8 very unusual or extreme. A value of 1 means that every EPS member is more extreme than the model climate. The thing to keep in mind is that significant snowfall, even in the winter, is unusual. Most days it doesn't snow. But there is a signal for some significant impacts possible according to the EPS. Also note that this index doesn't say how extreme. It could be a little more extreme than the model climate, or a lot more extreme. That's where the black lines come into play, that's the shift of tails (SOT). A value of 1 indicates that the 90th percentile of the forecast is one times the distance between the 90th and 99th percentile of the model climate. A value of 10 would be ten times. A SOT appears when at least 10% of EPS members are forecasting an event greater than the model climate extreme. Say the model climate extreme is 6 inches and the difference between the model climate 90th and 99th percentile is 1 inch, with a SOT value somewhere between 0 and 1 (call it 0.5) this 90th percentile forecast would be 6.5 inches. Notice how the SOT values are higher and the EFI higher down around DC. That's because snow is more extreme in that area than New England, and more likely to be an extreme event based on forecasts.
×
×
  • Create New...