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Tuesday, January 16, 2007

WINTER BEGINS IN THE EAST

Ever have one of those days where you have so many problems because of your owns success that you just fall behind the matter how hard you try and a stick the schedule?
I still have not made it to the gym and I still No inner yet and this is already 90 minutes late.

If you recall a couple blog entries from way back last week

Saturday, Jan 06 the COMING STUNNING pattern flip
JAN 8 -- The trend is MY friend


In those entries I made two very important points. The first one was that by any definition of terms one wanted to use the pattern was going to flip provided of course if you had a correct understanding what was driving the atmosphere. Over the weekend a well-known meteorologist came out with some specious assertions about what constitutes a pattern change ... and used a certain criteria which nobody ever knew about until he asserted it.

The other important point I made is that it's imperative that one simply does NOT focus on ones own backyard as to whether not there is a pattern change. For example it is of course easily possible for a significant pattern change to occur over North America but at your particular location say the East Coast or perhaps the West Coast the overall pattern in terms of actual weather conditions might not be significantly different. If one were to base their assessment on whether the pattern change simply on own backyard then you got nothing because the criteria is so subjective and professional meteorologists outa to be able to look at things in totality rather than their own backyard.

To drive home the point about how fundamentally different the overall pattern has been and what's it going to be I posted the East to images at another form or I occasionally make an obnoxious comment.... and as you can see these images really speak themselves about how totally different pattern has become.

http://www.wxrisk.com/MODELFOLDERS/today/t-6.gif

http://www.wxrisk.com/MODELFOLDERS/today/abc.gif


JAN 19

The first issue to deal with is the triple point low-pressure area develops on the next Arctic front that sweeps thru Jan 118 over the Plains & Midwest and into the Northeast Jan 19. The NAM / WRF seems to be the most of aggressive with the development of the triple point low close enough to the coast so that it produces the first snow the season along the coastal areas all the Midlantic. Then as the feature movies off the coast and rapidly develops into a major system off the SE New England coast... and much better chance exists for the first significant snow for much of central and eastern New England late on the 19th.

Because we did not yet had any high latitude blocking or a 50-50 low over one-year Newfoundland Canada the surface low that forms on the triple point develops very rapidly and there's nothing to slow it down. In addition of the other problem for the coastal areas of the middle Atlantic is that the boundary level temperatures may be too warm to support all snow.
However what's really important out this feature is what it does as Nows off the coast. First the potential exists for a significant snow storm for New England as this low goes BOOM nar 40 and 70 and points to the north.

But more importantly is that this system plays a critical role in what happens to the NEXT and and potentially much bigger winter storm for the East Coast on January 21 --22.

JAN 21-22

Here is the 1st important rule than or first obstacle that must be overcome as the talk about the next system and its potential to be the first significant what do storm of the East Coast Jan 21-22. IF the Low that is suppose to BOMB out off the New England coast January 19 does NOT do so... the next event JAN 21-22 will NOT be a significant winter storm for the I-95 big cities of the Northeast and the precipitation fall primarily as RAIN.

This map from the midday European shows exactly why this is the case. The first map is the 120 hour European which shows the system from January 19 has now bombed out off th New England coast and we have a deep close cut off 500 Low over southeastern Canada - a classic 50/50 Low.
http://www.wxrisk.com/MODELFOLDERS/today/12z120ec.gif


That Low feature does TWO things. After the cold front comes through in the 19th in the new Arctic High slides into the eastern US the 50-50 low blocks the cold High for moving rapidly off the coast and more importantly establishes a strong PJ in a CONFULENT flow across the Great Lakes and far northern New England. This becomes the cold air source for the Arctic high over northern New England Jan 20-21.

It is for these two very important reasons that the next system and its potential for Bringing a significant winter storm toi the NE is heavily dependent upon the first Low of the New England coast on January 20 bombing out.

Parenthetically at 72 hours the midday Euro does not have a significant system forming on the triple point over the Middle Atlantic states... and the low does not develop until it passes through 40/70..

The next important aspect to the potential for the event on January 21-22 is the strong shortwave over the Southwest. The midday European shows this feature the best.
http://www.meteo.psu.edu/~gadomski/ECMWF_12z/f72.gif

12 z Tuesday Ukmet concurs
http://www.meteo.psu.edu/~gadomski/UKHEMI_12z/f96.gif

That shortwave is going to develop a significant amount of overrunning precip over southern & central TX and given the fact that the Arctic HIGH will be fairly South the potential exists for significant snow and ice event over places such as San Antonio Dallas into the upper Delta and the the Tennessee Valley Jan 19-20.
http://www.meteo.psu.edu/~gadomski/ECMWF_12z/f196.gif
http://www.meteo.psu.edu/~gadomski/ECMWF_12z/f120.gif
http://www.meteo.psu.edu/~gadomski/ECMWF_12z/f144.gif



The midday op GFS solution as well as the gfs 12z ensembles showed a reasonable solution at this time ... with the primary Low & the secondary Low at almost equal strength with some sort precipitation passing over the Northeast but not as an impressive system.
http://www.meteo.psu.edu/~gadomski/ENSHGT_12z/f144.html
http://www.meteo.psu.edu/~gadomski/ENSPRS_12z/f144.html

However most of the medium-range models are just now focusing on the developing - NAO that is forming over southern Greenland. Again once his feature IS in place AND we have that deep low over southeastern Canada -- the 50/50 Low -- when the main shortwave energy in the subtropical jet that comes out of lower TX it wil be forced to stay to the south as will the primary Low.

If we were taken made a European verbatim we would see a significant ice storm over the Southeast states and then snow over the I-95 cities that turned over to rain because the cold High slides out to sea... while inland some places could see a significant snow. And in this sort of set up my new location up here near Leesburg VA could benefit from the that kind of set up.
Behind that feature we had yet another plunge of Arctic air into the central and eastern CONUS.
Taking a look at the hemispheric depiction of the mean 8-10 day 500 MB heights we can see that the operationally European which yesterday was showing a fierce REX block developing over Greenland-- and hence a very strong negative NAO -- is now no longer showing that feature!
http://www.meteo.psu.edu/~gadomski/ECMWF_12z/hgtcomp.html

On the other hand the operational Tuesday 12z GFS which yesterday was showing a 500 MB ridge extending NOT into Greenland but east of it into Ireland... is now showing a severe negative NAO because the model is showing strong Omega block configuration developing there as well.


The 240 hour GFS ensembles and midday are amazingly cold and show a lot of consistency.
http://www.meteo.psu.edu/~gadomski/ENSHGT_12z/f240.html

The operational run shows a strong Arctic front already moving through with the Deep trough right along the East Coast... with several members showing equally strong troughs and some of them further to the WEST -- p04 p05 p06 p07 p08 p09


lastly have to mention the appearance on the operational GFS again of a severe Arctic outbreak developing sometime around the 26 427 the January. This first Started showing up late last week on some of the operational runs but of course we all know about the GFS famous cold bias.
Again however if we look at the GFS ensembles we see some support for the severe Arctic outbreak the operational model showing at midday.

the top row furthest LEFT represents the operational run... with the following mebers supporting the idea of a major arctic outbreak occurring at this time frame or about to occur P09 p07 p06 p05 p01
http://www.meteo.psu.edu/~gadomski/ENSHGT_12z/f336.gif

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