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Medium-long range thread


tombo82685

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Wednesday, January 4, 2012 7:00 PM - 8:00 PM EST

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Webinar Registration

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Nice job by the Accuweather marketing team. Sure, I suppose "parts" of the US will experience brutal winter weather. And I sure that the northeast and New England will experience major storms (we've been having them ever since Irene). But a true weenie could read that as, "brutal winter storms for the northeast and New England".

Well played Accuweather. ;)

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Tonight's Euro is a swing and a miss for the 1/4 potential storm - for the op at least. Let's examine why, because it shows how much of a thread-the-needle event this will be.

Tue's 12z:

post-1820-0-00092200-1325057730.png

534 dam contour closed off in the east. Noticed the circled vort over Alberta. Ridge axis runs roughly Winnipeg to Rapid City.

Now look at tonight's run (Wed's 0z):

post-1820-0-29242200-1325057801.png

The trough is quite similarly modeled, for being 7 days out anyway, and I think given that the pattern is still very similar, we can consider this run to be a success even without a significant snowstorm.

The northwestern vort is more amped...look at the 552 dam contour dipping into the CONUS this run. On the MT/SK border, there's just a 6 dam h5 height difference between the two runs, but that's significant in this case. Because that vort is more amped (or at least closer to closing off), it pushes the ridge axis a bit farther east and flattens it out just a bit, just enough that the EC trough can't close off and we end up with a disorganized mess trying to form an SLP over the open ocean.

Personally I'm just glad to finally see an EC trough modeled consistently. That should be considered a win, and the major take-away here.

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Personally I'm just glad to finally see an EC trough modeled consistently. That should be considered a win, and the major take-away here.

FWIW, the GGEM lies in the Euro camp with the mean trof location but is really weak with the NW vorticity that TR pointed out on the Euro.....lacks that feature almost completely:

00zggem500mbvort144.gif

glancing blow:

00zggem850mbTSLPp06144.gif

Why were there so many concerns yesterday regarding this as becoming a cutter?? I don't see that solution as plausible due to the mean trof axis being where it is progged. It's either a glancing coastal hit or a swing and a miss imho. Any thoughts?

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Really not sure why people are expecting this cold shot (Jan 3-7) to be more than short lived. We're getting the IO MJO/MT response I wrote about last week a little earlier than I expected (see TC Thane and TC 4S), but once the forcing moves back over the Maritime Continent, we'll go right back to the torchy pattern we had for most of December.

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Really not sure why people are expecting this cold shot (Jan 3-7) to be more than short lived. We're getting the IO MJO/MT response I wrote about last week a little earlier than I expected (see TC Thane and TC 4S), but once the forcing moves back over the Maritime Continent, we'll go right back to the torchy pattern we had for most of December.

When i think of torch i think of 60 degree highs or better. Did we have many of those in December? I realize the month was well above normal but it just doesn't seem like it was a all out blow torch month.

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When i think of torch i think of 60 degree highs or better. Did we have many of those in December? I realize the month was well above normal but it just doesn't seem like it was a all out blow torch month.

Yeah, I guess it's semantics. When I think of "torch," I think of >+6 anomalies over a prolonged period of time, which we definitely had in Dec. But it's different for me given the field I work in.

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Yeah, I guess it's semantics. When I think of "torch," I think of >+6 anomalies over a prolonged period of time, which we definitely had in Dec. But it's different for me given the field I work in.

I wasn't disagreeing with you Adam or being picky about it. I'm just in the camp of if it isn't going to snow, let it be warm enough for me to golf. I didn't do any in December because it seemed on the warmest days it was pouring and then it would be windy with temps in the 40's after the rain. Bring on the super torch if the snow ain't coming. :sizzle:

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When i think of torch i think of 60 degree highs or better. Did we have many of those in December? I realize the month was well above normal but it just doesn't seem like it was a all out blow torch month.

PHL has had 5 days with highs in the 60s. Contrast that with just 1 day with a high below 40.

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PHL has had 5 days with highs in the 60s. Contrast that with just 1 day with a high below 40.

I just checked the month for Lancaster. We had one day reach 60 with 3 days of a high below 40 and 9 days of measurable rainfall. If this is what January has in store, i say bring on April.

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Really not sure why people are expecting this cold shot (Jan 3-7) to be more than short lived. We're getting the IO MJO/MT response I wrote about last week a little earlier than I expected (see TC Thane and TC 4S), but once the forcing moves back over the Maritime Continent, we'll go right back to the torchy pattern we had for most of December.

What mechanism exactly is driving this pattern?? I've heard alot of things being tossed around like the PNA, the QBO, the MJO, the NAO/AO, etc, but which of these is causing the torch and needs to change in order for us to have some average weather this year? Thanks in advance.

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What mechanism exactly is driving this pattern?? I've heard alot of things being tossed around like the PNA, the QBO, the MJO, the NAO/AO, etc, but which of these is causing the torch and needs to change in order for us to have some average weather this year? Thanks in advance.

I attribute it to two things: the tropical convection being focused over the Maritime Continent ("the MJO" - even though it's not a true MJO wave) enhances the subtropical ridge over the Pacific, leading to a +EPO state. Also, the polar vortex has been fairly strong/cold, leading to a +AO/+NAO state over the Atlantic. With no mechanism to generate blocking, the US has been flooded with Pacific air, leading to strong positive temperature anomalies.

In order for it to change, we need tropical convection to propagate eastward towards the dateline in order to force a -EPO or +PNA. Also, a weaker polar vortex disrupted by vertically, poleward propagating Rossby waves would also help force blocking over the Atlantic. Absent either of those things (which I don't see for at least 3 weeks), we'll maintain a dominant La Nina pattern, with the SE ridge in place, and storms either cutting to our west with rain or moving out to sea with no block in place.

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I wasn't disagreeing with you Adam or being picky about it. I'm just in the camp of if it isn't going to snow, let it be warm enough for me to golf. I didn't do any in December because it seemed on the warmest days it was pouring and then it would be windy with temps in the 40's after the rain. Bring on the super torch if the snow ain't coming. :sizzle:

Yeah it was kind of surreal golfing in short sleeves on the first day of winter last week. I do agree with you windy and cold and 17F does nothing for me except increase the amount of the check I write to PSE&G.

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Really not sure why people are expecting this cold shot (Jan 3-7) to be more than short lived. We're getting the IO MJO/MT response I wrote about last week a little earlier than I expected (see TC Thane and TC 4S), but once the forcing moves back over the Maritime Continent, we'll go right back to the torchy pattern we had for most of December.

I haven't looked at the forecast 850mb winds to see if it has a chance and this is more GFS based, but shouldn't there be another shot about the middle of the month (if) the MJO gets to those more favorable phases?

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I haven't looked at the forecast 850mb winds to see if it has a chance and this is more GFS based, but shouldn't there be another shot about the middle of the month (if) the MJO gets to those more favorable phases?

Sure, but that's a big if. It hasn't got to P7/P8 since early Nov and even then it was very weak. On top of that, the Euro ensemble and weeklies and the Roundy progs all show convection stalling over the Maritime Continent.

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Sure, but that's a big if. It hasn't got to P7/P8 since early Nov and even then it was very weak. On top of that, the Euro ensemble and weeklies and the Roundy progs all show convection stalling over the Maritime Continent.

I was just glancing at the Berlin site this morning, it doesn't look like that ssw had much downward success either. Yup one big if.

:yikes:

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