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December Forecast Discussion


REDMK6GLI

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I know people are becoming increasingly impatient with all of these long range threats that never seem to pan out, but the Euro has at least 3 storm threats over the next ten days including the one around New Years. The key will be the amplification of the Western ridge. As long as we have a screaming Pacific jet knocking everything down, the pattern won't allow much amplification.

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No Davis Strait centered -AO block to keep the STJ from riding too far north

when an amplified system ejects form the SW. There is nothing to

keep the SE Ridge suppressed for even the third system in the forecast.

The closer we get to the forecast, the warmer the solutions get. Notice 

how the earlier 240 hr forecast for the 28th had a -AO pattern

which the model is now backing away from. 

 

 

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No Davis Strait centered -AO block to keep the STJ from riding too far north

when an amplified system ejects form the SW. There is nothing to

keep the SE Ridge suppressed for even the third system in the forecast.

The closer we get to the forecast, the warmer the solutions get. Notice 

how the earlier 240 hr forecast for the 28th had a -AO pattern

which the model is now backing away from. 

 

attachicon.gifecmwf_z500a_nhem_7.png

 

attachicon.gif10.png

Even though multiple Red taggers, deeply respected, indicated major excitement over that same Davis Strait block only 3 days ago. I think thats where weenie impatience is eminating from. The cold & stormy pattern, a virtual certainty 5 days ago, now appears mirage like. We can do nothing but wait till the details shake out.

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Even though multiple Red taggers, deeply respected, indicated major excitement over that same Davis Strait block only 3 days ago. I think thats where weenie impatience is eminating from. The cold & stormy pattern, a virtual certainty 5 days ago, now appears mirage like. We can do nothing but wait till the details shake out.

 

The problem with that was the Euro was phasing the northern and southern streams on Wednesday that was pumping

the heights up toward Greenland. Now the storm is going to be much weaker and not have much of an impact on

the 500 mb height field.

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The problem with that was the Euro was phasing the northern and southern streams on Wednesday that was pumping

the heights up toward Greenland. Now the storm is going to be much weaker and not have much of an impact on

the 500 mb height field.

 

 

It's because of the progressive nature to the pattern...the PAC jet still has an influence IMO. But I would also think that same feature could prevent the storm around New Years from cutting...it may actually become weak and sheared out like this weekend was IMO. 

 

Edit: Probably not to that same EXTENT, but something more sheared out than current guidance certainly seems possible. 

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No Davis Strait centered -AO block to keep the STJ from riding too far north

when an amplified system ejects form the SW. There is nothing to

keep the SE Ridge suppressed for even the third system in the forecast.

The closer we get to the forecast, the warmer the solutions get. Notice

how the earlier 240 hr forecast for the 28th had a -AO pattern

which the model is now backing away from.

ecmwf_z500a_nhem_7.png

10.png

True. But the euro has been over amplifying systems in the mid range...last weekend for example and the Xmass cutter...its a progressive pattern, I think we have a shot

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I am not sure if this was worked on already, but I would love if someone (Unc usually develops lovely lists) could come up with a list of snowless, warm Decembers, in a slight Nino with no NA blocking and how Jan-Feb-Mar turned out. I would venture a guess and say not very good.

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True. But the euro has been over amplifying systems in the mid range...last weekend for example and the Xmass cutter...its a progressive pattern, I think we have a shot

Agree .  There is true arctic air behind this front , the press will be east .  Would worry about one of these working .

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I am not sure if this was worked on already, but I would love if someone (Unc usually develops lovely lists) could come up with a list of snowless, warm Decembers, in a slight Nino with no NA blocking and how Jan-Feb-Mar turned out. I would venture a guess and say not very good.

 

Well since 1950, Decembers with less then 2" of snow in KNYC yielded only an average of 16.5" for the seasonal total.

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I have 33 seasons at Philadelphia since 1950 with < 2" & the mean snow for the remainder of the season is 15.4" (median 13.6")

 

total seasonal snowfall during those years obviously includes OCT / NOV snow which is irrelevant at this point

 

I must've missed a few seasons.

NYC is definitely 16.5" though.

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I must've missed a few seasons.

NYC is definitely 16.5" though.

 

I missed one season too, it's actually 34 seasons, mean -15.7" median - 13.7"

 

good (PHL wise) seasons the rest of the way were 1978, 1979, 2005, 1966, 1987, 1993 & 1994

 

1987 pops up in quite a bit this season, that year was a case a maximizing our windows of oppotunity

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I missed one season too, it's actually 34 seasons, mean -15.7" median - 13.7"

 

good (PHL wise) seasons the rest of the way were 1978, 1979, 2005, 1966, 1987, 1993 & 1994

 

1987 pops up in quite a bit this season, that year was a case a maximizing our windows of oppotunity

 

NYC has had 24 seasons since 1950 with 2" or less in December.

Only 1 season, 1977-1978, ended well above average (50.7").

1 more season ended near average, 1978-1979 (29.4") and the remaining 22 seasons ended below average.

14 seasons ended with less then 17".

 

Mean is 16.5", which for KNYC is pretty mediocre.

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NYC has had 24 seasons since 1950 with 2" or less in December.

Only 1 season, 1977-1978, ended well above average (50.7").

1 more season ended near average, 1978-1979 (29.4") and the remaining 22 seasons ended below average.

14 seasons ended with less then 17".

 

Mean is 16.5", which for KNYC is pretty mediocre.

 

Ag3,  thanks for the stats.  How many of those Decembers had over 5" of monthly liquid equiv precip?

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euro has not handled this pattern well!

But here is thing though: the King has been the best model for several years going with others lagging behind and GFS and NAm largely becoming a bad joke, except on certain rare ocassions within the 48-72 hr window so if the Euro is having difficulties as it appears to be now where do we turn? For all intents and purposes and even from pros it appears everyone is a bit dumbstruck outside of 5-7 day window. When you are expecting a radical pattern change right outside that window that leaves us all in a difficult predicament.

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No model really has, the GFS having a progressive bias has probably helped it look better...I would not be surprised if the NOGAPS has been doing very well too given its such a progressive model.

 

Not a big deal, but its the NAVGEM now.. NOGAPS was retired (wouldn't surprise me if some sites still call it the NOGAPS, though... )

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losing the midwest bomb was probably a major factor in the modeled increase of the AO recently.

http://mp1.met.psu.edu/~fxg1/ECMWF0.5_12z/tr24f96.php

the delay in intensification means the storm enhances the PV instead of disrupting it. as you go forward in time the system becomes more consolidated in SE canada instead of occluding and broken up on prior runs

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losing the midwest bomb was probably a major factor in the modeled increase of the AO recently.

http://mp1.met.psu.edu/~fxg1/ECMWF0.5_12z/tr24f96.php

the delay in intensification means the storm enhances the PV instead of disrupting it. as you go forward in time the system becomes more consolidated in SE canada instead of occluding and broken up on prior runs

 

If we were really relying on that to turn the AO negative long term it was not going to work, that probably would have been only a 5-7 day pattern change that flipped right back.

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losing the midwest bomb was probably a major factor in the modeled increase of the AO recently.http://mp1.met.psu.edu/~fxg1/ECMWF0.5_12z/tr24f96.phpthe delay in intensification means the storm enhances the PV instead of disrupting it. as you go forward in time the system becomes more consolidated in SE canada instead of occluding and broken up on prior runs

Are the euro ensembles over doing the EC ridge in the face of its own ensemble killing the MJO in phase 5 and a declining SOI.

Shouldn't that argue for a trough in the east like the GFS sees ?

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Euro pops a nice little frontal wave this weekend for 2 - 5" event. That would be the one to save winter, haha but it's 6 days away and we all know what that means. Can only hope it's better this go around.

 

This weekend? FWIW, it shows it for Monday into Tuesday.

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Interesting how that system looks very sheared to an extent on the 06Z GFS and Euro...possibly the Pac jet at work again despite the SE ridge.

Has a post SB look to me . Pressing arctic front with low level cold air that will easily funnel to the base of the trough .

It meets the SE ridge there`s resistance and the center moves NE to a point .

 

For me it`s either snow or no .  If it misses it would be to the S and not rain .

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