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Who Needs Hazel When You Have Sandy


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No I think it's a possibility. Probably more likely than a wild phase that sends the thing into PA as a 970mb hybrid lol

Oh I wasn't sure what you meant because as modeled the low moves slowly. I really don't know what to think. Sometimes the globals get phase happy and capture the low and whip it back to the west too quickly, but the blocking is also modeled to be ridiculous..so perhaps some validity there. GEFS sort of have the Noel idea, we'll see what the EC ensembles do.

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Oh I wasn't sure what you meant because as modeled the low moves slowly. I really don't know what to think. Sometimes the globals get phase happy and capture the low and whip it back to the west too quickly, but the blocking is also modeled to be ridiculous..so perhaps some validity there. GEFS sort of have the Noel idea, we'll see what the EC ensembles do.

Yeah I think the Noel idea at the end of the day is probably most likely.

I agree that the globals seem to love to D+7 super phase only to back off on later runs. Agreed about the blocking downstream... now it's just an issue of timing shortwaves out.

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So the key in all of these runs is with the ridging downstream of the western trough by the middle of the week, and the incredible ridging from the Bering Straight to Greenland.

For past New England TCs, a -NAO transitioning to a highly positive NAO is a rather large signal. In this case, the negative NAO isn't budging. BUT the consistent model projection is to bridge the eastern US ridge with the -NAO Greenland ridge creating this monster deep layer southerly flow from the Mid Atlantic to the North Pole!

Notice that we have largely achieved similar solutions with pretty variable evolutions of the incoming trough from the west. The consistent feature is this ridge-bridge.

Another huge signal in the past New England TC database is the TC being supported beneath the equatorward entrance region of a jet streak over the POSITIVE NAO ridging over the Atlantic. In this case, we have that jet streak and supportive quadrant over the TC, but the jet streak is on the upstream side of the ridge and oriented nearly straight south-north!! Pretty awesome.

Great post regarding the ridge bridge. As long as that bridge is connected, it's hard to imagine the system escaping to the east.

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Great post regarding the ridge bridge. As long as that bridge is connected, it's hard to imagine the system escaping to the east.

Monster rex block to monster ridge bridge to monster omega block between days 5 and 10. Pretty much the ideal scenario for getting something into the east coast.

The baroclinic interaction with Sandy and the westerlies over NOAM will determine whether this is just a bore or a storm that leads to big hydro issues or a legit hurricane-like event.

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Before we all start hallucinating with the latest 192 hour model guidance, lets look at the pattern in place. There is a pretty impressive blocking pattern that is being depicted by nearly all of the modeling in the 72-92 hour time frame.

sxjj7t.gif

So why is the blocking important? Because it sets the stage for the possible nor'easter being depicted by the latest numerical guidance. Looking at the 72 hour frame above, we have a nice 534 dam low located just north of Newfoundland. This low can't continue to progress northward because its blocked by the amplified anomalous ridging between 60-70 N. The end solution is that this low is force southeastward, a very atypical track for a mid-latitude low pressure in this part of the world (as a greenland low track is more favored).

103bkuv.gif

By 120 hours, you see this same low pressure I was alluding to diving to the southeast, in which it will continued to get blocked by the ridging overhead (a Rex Block). Such a configuration prevents Invest 99L from recurving out into the open atlantic, since the flow on the backside of this low pressure is northerly in the low-mid level steering block. Thus, its increasingly likely that 99L will have to impact the US in some fashion. I think this part of the forecast I'm pretty confident in. What sort of interaction we end up with is of much more uncertainty, because that is dependent on the flow originating over the West Pacific. The interaction of ex-Prapiroon with an extratropical disturbance is expected to be the catalysis of a major rige building event that will destroy the current -PNA in place. However, these TC/ET interactions are typically very poorly modeled, and Prapiroon has been a pretty prime example of this (its several days late and further west per last weeks guidance which this ET event).

At this point, I think there is a possibility for a very high amplitude event (along the lines of the ECMWF and GGEM) but its far too early to know if we are getting our shortwaves lining up just right for the proper TC/ET interaction. If the mid-latitudes don't cooperate, 99L could still be a significant nor'easter, but it would be far too warm for any snow and we wouldn't be looking at anything more substancial than a Noel 2007 solution.

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Before we all start hallucinating with the latest 192 hour model guidance, lets look at the pattern in place. There is a pretty impressive blocking pattern that is being depicted by nearly all of the modeling in the 72-92 hour time frame.

sxjj7t.gif

So why is the blocking important? Because it sets the stage for the possible nor'easter being depicted by the latest numerical guidance. Looking at the 72 hour frame above, we have a nice 534 dam low located just north of Newfoundland. This low can't continue to progress northward because its blocked by the amplified anomalous ridging between 60-70 N. The end solution is that this low is force southeastward, a very atypical track for a mid-latitude low pressure in this part of the world (as a greenland low track is more favored).

103bkuv.gif

By 120 hours, you see this same low pressure I was alluding to diving to the southeast, in which it will continued to get blocked by the ridging overhead (a Rex Block). Such a configuration prevents Invest 99L from recurving out into the open atlantic, since the flow on the backside of this low pressure is northerly in the low-mid level steering block. Thus, its increasingly likely that 99L will have to impact the US in some fashion. I think this part of the forecast I'm pretty confident in. What sort of interaction we end up with is of much more uncertainty, because that is dependent on the flow originating over the West Pacific. The interaction of ex-Prapiroon with an extratropical disturbance is expected to be the catalysis of a major rige building event that will destroy the current -PNA in place. However, these TC/ET interactions are typically very poorly modeled, and Prapiroon has been a pretty prime example of this (its several days late and further west per last weeks guidance which this ET event).

At this point, I think there is a possibility for a very high amplitude event (along the lines of the ECMWF and GGEM) but its far too early to know if we are getting our shortwaves lining up just right for the proper TC/ET interaction. If the mid-latitudes don't cooperate, 99L could still be a significant nor'easter, but it would be far too warm for any snow and we wouldn't be looking at anything more substancial than a Noel 2009 solution.

The catalyst is a s/w that rips off from the GOA low. If you look at h5 on the euro, it's quite convoluted up there.

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The catalyst is a s/w that rips off from the GOA low. If you look at h5 on the euro, it's quite convoluted up there.

Yeah that's the thing... I think we can all agree the pattern is conducive for a highly anomalous track of whatever comes out of the Caribbean thanks to highly anomalous ridging to the northeast.

The issue is going to be the baroclinic interaction between the westerlies and 99-L. Timing, shortwave orientation, and exact track of 99-L will be very tough to pin down for some time.

I like the Noel (2007 I think) analog as the kind of solution that is quite plausible but not particularly exciting from a sensible wx perspective.

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No about a strengthening Extratropical cyclone coming in somewhere over us or south of us. I think that is the most probable occurrence right now.

Nothing is escaping east of the east coast with that blocking. Nothing like Noel

Well... Noel had the downstream blocking that prevented it from recurving out to sea.

I think it will still take a mini miracle for a full-on phase south of our latitude to capture this storm and explosively deepen it. It's possible... but it's incredibly rare... and quite unlikely here.

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Well... Noel had the downstream blocking that prevented it from recurving out to sea.

I think it will still take a mini miracle for a full-on phase south of our latitude to capture this storm and explosively deepen it. It's possible... but it's incredibly rare... and quite unlikely here.

When some very well respected mets like Raleighwx,Icebreaker, and others from outside our region entertain that this is a very real possibility..it should make folks take notice

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Well... Noel had the downstream blocking that prevented it from recurving out to sea.

I think it will still take a mini miracle for a full-on phase south of our latitude to capture this storm and explosively deepen it. It's possible... but it's incredibly rare... and quite unlikely here.

Maybe 5% chance right now

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When some very well respected mets like Raleighwx,Icebreaker, and others from outside our region entertain that this is a very real possibility..it should make folks take notice

I mean if you're expecting a hurricane than I wouldn't say it's a "very real possibility"... if you're expecting a typical/strong nor'easter type of solution then yeah it's a real possibility.

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The catalyst is a s/w that rips off from the GOA low. If you look at h5 on the euro, it's quite convoluted up there.

Indeed... the GOA low is a direct consequence of the ridge building event taking place with the remnants of Prapiroon interacting with a mid-latitude shortwave.

Here is a nice annotation of the forthcoming interaction below. These type TC/ET interactions can be difficult for the modeling to handle, but the real uncertainty lies when the GOA low cutoffs below a formidable Rex block over Alaska. These little shortwave pieces that eject out of this large upper level disturbance are pretty much nearly impossible to forecast beyond day 5, especially in a region that has poor upper air observation sampling.

orrz7t.gif

I should mention that this is a dynamic tropopause (DT) map, plotting pressure on the DT surface, winds, and cyclonic relative vorticity layer mean average from 925-850 hPa.

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Nobody was saying ots won't happen, just that to just about lock any solution in at this point isn't right. Ots very well could happen. And Noreaster has a history of saying everything will bust well in advance.

I know he's a bit of a troll. In this case though he's right. Odds most certainly favor the solution he mentioned. While a more extreme/anomalous solution is possible it's highly unlikely even though most of the 12z runs showed it happening.

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18z GFS refuses to give up on it... although Sandy goes OTS, there's still a weaker retrograding low, widespread rains but still less impressive than the 6z-12z runs. Model hugging is pointless 192 hours out, the potential is clearly there for a significant storm to affect the Northeast, but as with any extreme solution this far out it's only a possibility.

gfs_namer_240_850_temp_mslp_precip.gif

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18z GFS refuses to give up on it... although Sandy goes OTS, there's still a weaker retrograding low, widespread rains but still less impressive than the 6z-12z runs. Model hugging is pointless 192 hours out, the potential is clearly there for a significant storm to affect the Northeast, but as with any extreme solution this far out it's only a possibility.

gfs_namer_240_850_temp_mslp_precip.gif

So it does. Maybe the EURO won't change that much.

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What's up with the massive low pressure over Alaska in the long range? Ugly. Does that have any support in the euro ensembles?

Yes it does unfortunately...AK vortex comes back on the ensembles....but at least it does look like it starts to erode again and reload to the SW by the end of the ensemble run. Still too early for me to get nervous like back in Nov 2011...but if this were 3 weeks from now, I'd start getting pretty concerned.

Siberian snow cover is doing very well right now too, so that is something going for us that was not last year too.

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What's up with the massive low pressure over Alaska in the long range? Ugly. Does that have any support in the euro ensembles?

Yeah we've mentioned it for a few days now. It's orientation is such that we actually get some ridging out of it, but optimally, we would want it further SW in the winter.

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