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Pattern/storm inverted trough thread early Jan


Damage In Tolland

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At this point it wouldn't surprise me if it were partly sunny to mostly cloudy with a passing snow flurry for the duration.

[Enter sad trumpet: Whah wah wahhhh]

Flow is just too fast in the deep south and SE. Heights [probably] were just too high over the lower TV regions and adjacent Gulf and Florida.

In order for phasing to occur the frequency in the longitudinal direction needs to compliment that in the latitude (x and y corrdinate respectively). Here, too much longitudinal component results because the balance geostrophic medium was too compressed, causing winds to howl over 60kts. This is a destructive wave interference on S/W passing through, which effectively weakens the "trigger" for southward subsuming SPV. Result is that the SPV begins to come down, but it is limited as to how much [as well as being sheared] and instead of sloping negative, the result takes on a "tea-cup" in structure ... The field is just a mess this way and won't cohesive cyclogen the way earlier resolutions suggest.

I was speaking to Harv about this last night and he agrees, this can still come together, but it is amid the remoter of possibilities given to the immense perfection in timing that needs to take place in order to compensate for an overall wave interference pattern that exists between Ontario and the SE U.S.

Better luck on the next one, but already ... heh, not seeing a vastly improved medium down there.

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So we have 3 scenarios then, broadly

1. dream scenario, the sw digs hard, doesn't get pulled offshore, deepens, curls and pulls the whole pv down and under. Blizzard

2. the pv stays north, doesn't come under, low pressure develops offshore and deepens setting up a trough between the strong pv sitting back in nyc or the eastern great lakes which creates a norlun type trough somewhere and some scattered/light snow elsewhere

3. the pv does come under eventually but in a spread out diffuse manner with energy getting pulled out to sea in the intensifying offshore low. The result is some sort of inverted trough and some general light snow cause by have the pv energy underneath us.

Is this right and what do ya'll think of the odds of either scenario.

Another thought here is that if we get a low level ne e or se flow with all this energy to our west, this could create some long duration light snow in areas of elevation. Is that a possible scenario?

Thanks for your thoughts

It's possible 2 and 3 will have similar results. Both of these models have a lead s/w that develops a low way ots. Having the PV under sne, MAY extend the period of lighter snows, but the problem is that all the good PVA (positive vorticity advection) becomes disorganized and weak. We have left with pockets of unorganized forcing.

Yeah it's possible long duration erly flow may benefit someone. It could be closer to the coast with the typical land/sea convergence stuff...or even perhaps due to a weak CF separating e-ne winds vs more nrly winds. The other thing, is if we can get some good se flow from 950-850. This may help the upslope areas further west and nw...but again, this is more mesoscale stuff that will not be determined until we near the event.

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Nothing to write home about though. Probably a narrow stripe of 6-12" from the inverted trough, and a general 1-4" for everyone else. Pedestrian.

wheres the max QPF area most likely to set up in an event like this? I think I'm gonna read up on inverted troughs and try to learn a bit more about them. Wheres the modeled jackpot right now?

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At this point it wouldn't surprise me if it were partly sunny to mostly cloudy with a passing snow flurry for the duration.

[Enter sad trumpet: Whah wah wahhhh]

Flow is just too fast in the deep south and SE. Heights [probably] were just too high over the lower TV regions and adjacent Gulf and Florida.

In order for phasing to occur the frequency in the longitudinal direction needs to compliment that in the latitude (x and y corrdinate respectively). Here, too much longitudinal component results because the balance geostrophic medium was too compressed, causing winds to howl over 60kts. This is a destructive wave interference on S/W passing through, which effectively weakens the "trigger" for southward subsuming SPV. Result is that the SPV begins to come down, but it is limited as to how much [as well as being sheared] and instead of sloping negative, the result takes on a "tea-cup" in structure ... The field is just a mess this way and won't cohesive cyclogen the way earlier resolutions suggest.

I was speaking to Harv about this last night and he agrees, this can still come together, but it is amid the remoter of possibilities given to the immense perfection in timing that needs to take place in order to compensate for an overall wave interference pattern that exists between Ontario and the SE U.S.

Better luck on the next one, but already ... heh, not seeing a vastly improved medium down there.

Well said. Harv I think essentially said he wasn't even going to attempt to forecast this one yet.

The NAM is diving energy at a MUCH steeper angle this time but there's nothing to slow it down and it's shearing. It could come together but.

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Nothing to write home about though. Probably a narrow stripe of 6-12" from the inverted trough, and a general 1-4" for everyone else. Pedestrian.

I'll gladly take a widespread pedestrian event just to get something wintry going over a significant section of New England.

There is a large area of SW and central NE that has been in a snow drought since last Feb.

I know folks on the coast like to say "oh' it's the Ct River Valley snow hole" but that snow hole seems to be about 60 miles wide E to W and 100 miles long N to S.

I'd say that's a little more than a valley shadowing effect, no?

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It's possible 2 and 3 will have similar results. Both of these models have a lead s/w that develops a low way ots. Having the PV under sne, MAY extend the period of lighter snows, but the problem is that all the good PVA (positive vorticity advection) becomes disorganized and weak. We have left with pockets of unorganized forcing.

Yeah it's possible long duration erly flow may benefit someone. It could be closer to the coast with the typical land/sea convergence stuff...or even perhaps due to a weak CF separating e-ne winds vs more nrly winds. The other thing, is if we can get some good se flow from 950-850. This may help the upslope areas further west and nw...but again, this is more mesoscale stuff that will not be determined until we near the event.

Hey Scott thanks a lot for answering my questions.

I remember distinctly the Deco 19 and 21 SWFEs from 2008. The two events (around 12 inches each one) were separated by a 36 hour period of almost continuous light snow. I think this was probably due to leftover moisture tfrom system one and an easterly flow ahead of system 2 but I really have no idea. I am at 700 ft and there aren't any mountains to my ese. I'm about 300 ft higher than CON.

Anyhow...AST we await the SWFEs so we can all get love

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Hey Scott thanks a lot for answering my questions.

I remember distinctly the Deco 19 and 21 SWFEs from 2008. The two events (around 12 inches each one) were separated by a 36 hour period of almost continuous light snow. I think this was probably due to leftover moisture tfrom system one and an easterly flow ahead of system 2 but I really have no idea. I am at 700 ft and there aren't any mountains to my ese. I'm about 300 ft higher than CON.

Anyhow...AST we await the SWFEs so we can all get love

Yeah that was lots of leftover erly flow and moisture. Actually, 850 winds starting turning south, well ahead of the next system, which aided in waa and more light snow.

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wheres the max QPF area most likely to set up in an event like this? I think I'm gonna read up on inverted troughs and try to learn a bit more about them. Wheres the modeled jackpot right now?

Here's a paper to read on NORLUN events.

http://www.weatheranswer.com/public/NORLUN2.pdf

NORLUN is not interchangeable with inverted trough, but is related, and it's a good read.

I personally think we'll see the max QPF end up on the east slopes of the Berks. But it'll be very sensitive to the position of the trough axis. Modeled jackpot I think is a little further south, in NW CT and SW MA. I haven't taken a very close look at verbatim solutions yet though.

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