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E PA/NJ/DE Winter 2018-19 OBS Thread


Rtd208
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GFS beat out both the Euro and Ukie on the last system.  I'd be curious to know how often that happens (my guess is: not very).  It was relatively accurate even six days out.  Didn't waiver much, if at all.

Long range: I'm not sophisticated enough in this hobby to know all the details, but to me it appears one of the biggest issues is the MJO, which is more or less doing laps in the warm phases.  Not that it's warm, mind you, but I would think these phases deter a -NAO establishing itself.  Basically, a -NAO wants the warmer air over Greenland, while these MJO phases want the air over the CONUS.  In other words, a +NAO and these MJO phases sync up.  Again, pure speculation on my part because I don't know the extent of their interaction with one another.  Perhaps it's the other way around.

I will say, the one positive appears to be the AO dropping off.  Obviously, long-range determination hasn't been reliable this season, so that could end up either direction, but a -AO can definitely work in our favor.  As long as the MJO isn't super amped, I'm not overly worried about it.  The NAO just seems like it doesn't want to go negative and stay there lately, say within the last number of years.  Constantly transient.  I don't know why that is.

Getting excited about anything long-range this winter has been dangerous.  As long as the moisture conveyor remains active, I think there will be chances, everything else just needs to align at once.  We've certainly been close.

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The worry over the lack of a -NAO doesn't make sense to me. The Mid-Atlantic region typically needs a -NAO for a good snowstorm. We don't. All we need is a nice PNA and EPO which the 28th time period is advertising. Now the lack of an -NAO makes it easier for either a suppressed system or a amped system to occur, but would you rather have a broken down western ridge with mild Pacific air flooding the CONUS? The 28th time frame is a tricky, risky, and almost thread-the-needle type event. The orientation of the western ridge argues for a coastal hugger but the TPV orientation argues for a miss out to sea. But I'll take my chances. We've already struck out 4 or more times this winter. Might as well swing for the fences and hope for a home run.

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18 hours ago, Newman said:

The worry over the lack of a -NAO doesn't make sense to me. The Mid-Atlantic region typically needs a -NAO for a good snowstorm. We don't. All we need is a nice PNA and EPO which the 28th time period is advertising. Now the lack of an -NAO makes it easier for either a suppressed system or a amped system to occur, but would you rather have a broken down western ridge with mild Pacific air flooding the CONUS? The 28th time frame is a tricky, risky, and almost thread-the-needle type event. The orientation of the western ridge argues for a coastal hugger but the TPV orientation argues for a miss out to sea. But I'll take my chances. We've already struck out 4 or more times this winter. Might as well swing for the fences and hope for a home run.

I respectfully disagree good sir :). We need a slight neg nao here to slow the pattern down otherwise we are relying on perfect timing. We've scored in positive naos though due to the reasons you stated above. The AO tanking would be big because then at the very least we should see a few clippers and a supply of cold to work with so we can actually have true thump events even if it changes over. I think the 29th favors a coastal hugger or slight inland runner with a change over likely for 95 at this time. We'd do decent before us does though unlike this weekend because we'll have cold air to work with in place  If we can get the nao slightly negative though we'd be in business to suppress it a bit se.

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The NAM is very marginal for interior icing Wednesday. When precip arrives, temperatures for the interior are right around 30-31 degrees so it will start as ice.

namconus_T2m_neus_41.png

nam_2019-01-21-18Z_048_43.828_281.042_38

 

But just 3 hours later temperatures have risen into the 33-35 degree range. However, that is just the 2m temperatures. The roads may indeed still be below freezing with this arctic air mass we have in place. So even if the model is showing rain, it may still be freezing on contact.

namconus_T2m_neus_42.pngnam_2019-01-21-18Z_051_43.828_281.042_38

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