Good Read on Next 45 days into 2004-05 Winter Season

[Anonymous]

There has been a LOT of talk from some other sources about a BIG shift coming in the overall pattern for the Eastern US by the end of OCT and/ or early November... with the Trough position returning to the Eastern US. Not only is this utterly not true but the data is overwhelmingly against it and as such it is not really a forecast -- more like speculation or -removed-.

That being said let me say that the mild overall pattern over the eastern Half of the US here in the middle of October is NOT going to be the winter pattern... and YES this current pattern is a slowly evolving one and in fact in the right circumstances a DESIRABLE one if one want a active cold winter ... and I will explain that point in a bit more detail later.

Essentially over the next 30-45 days -- which will takes us to the end of November... the overall pattern will feature wetter than normal pattern over the Pacific Northwest… Upper Rockies… Upper Plains… Drier than Normal over the Southeast states. Temperatures will run Below Normal over the Western US… Near Normal temps over the Upper Plains and Midwest and Above Normal temps over the Southeast and Middle Atlantic. There is some "hint" that in week 4 the overall pattern may shift or begin to change .

I will start with a overview of the current pattern over the Northern Hemisphere at 500 MB on OCT 13. For most of the Spring and Summer 2004 the overall pattern featured a Ridge on the West coast / deep trough over the Eastern US. In the second week of August 2004 this pattern collapsed after the event of Hurricane Charley. The new pattern featured the trough in the western US and a Ridge over the western Atlantic and coastal areas of the southeast US which was conducive to numerous landfalling hurricanes. This pattern was a Positive Phase WP or WESTERN PACIFIC pattern.

However since 1 OCT the pattern over North America has been in transition and this can be seen in several areas… most notably with the sudden Decrease of Hurricane activity in October which was an event correctly forecasted by WXRISK but caught some forecasters by surprise.

Over the past few days I have begun to see strong signals that the first TRUE cool season pattern is now developing.

FIGURE 1 is a map of the SSTAs (Sea Surface Temperature Anomaly) as of OCT 15. I have highlighted THREE distinct areas which are having an impact on overall pattern. Any forecaster who attempts to see past day 10 that does not take into consideration SSTAs is not going to produce a good forecast. Research over the last 10 years has established a strong correlation between the Jet stream pattern’s position of Ridges and Trough and large pools of cold and warm Ocean water temperatures. In particular there is a strong correlation between the close proximity of large pools of cold Sea Surface temperatures and warm Sea surface Temperatures. There areas are referred to as "COUPLETS" .



AREA A is a significant COUPLET of warm and cold SSTA that covers the Northern Pacific from the China coast eastward to the West coast of the US. Please note the several pools of warm SSTA in close proximity of Cold water SSTA. This sort of couplet aligned in a west to east direction covering the entire north Pacific from coast to coast is a strong signal that a Pacific Jet Pattern -- known as a + EP Pattern --is about to begin….

AREA B is a large pool of warm SSTAs that covers all of the Bering Sea area. This pool of warm water was much large in late September so the trend with this pool of warm SSTAs is weakening.

The AREA C is a large pool of warm SSTA that have reappeared near Greenland over the past 10 days. If this pool of warm water increases it would be conducive for a Greenland Block to develop.

FIGURE 2 is the same map of SSTAs with the Jet stream patterns highlighted. The developing Greenland block can be seen clearly. Also I highlighted the very long COUPLET of cold and warm SSTA in the Northern Pacific which shows that the enhanced Pacific Jet is in very close proximity to this long couplet





DAY 10 ECMWF from OCT 15

The 00z run of the ECMWF ( the European) model shows very clear and unmistakable signs of a very strong + EP or eastern Pacific Pattern developing over the Northern Hemisphere. The very deep Polar Vortex (PV) can be seen clearly and is located over the Bering sea and far western Alaska. With a Huge PV of this size there is going to be a lot of zonal or due West to East flow across the Pacific Ocean... which is referred to the Pacific Jet-- but also note the Ridge of High pressure over the central Pacific which acts as a Choke point for the Pacific jet enhancing its power and velocities. I outlined this feature in BLACK along with the words "PAC JET". And lastly we can see a Greenland Block (which is a form of the Negative NAO pattern).



That model run as well as the 00z 16 OCT run take us to OCT 27-30 but then what happens? Typically with Positive EP pattern they can last several weeks. Indeed looking at 0z OCT 15 GFS ensemble mean… we see the pattern staying very much the same as the day 10 ECMWF is showing. That is the PV is over in eastern SIBERIA which implies a slow Retrogression of the Day position of the PV over Alaska. Either way the GFS ensemble is clear…. That the Pacific Jet will carve out a deep trough just off the West coast of the Pacific Ocean and feed a series of Low pressure areas into the western and central portions of North America.





I cannot figure why snownuts and winter weather folks get worried about warm OCTOBERS!? I mean who gives a poop if the temps are Above Normal or Below Normal in October? Most of the time cold pattern in OCT and NOVEMBER will NOT last through to March. In a lot of ways the overall pattern is similar to the middle of OCT from last year!





What is far more important folks is the development of early season cold over the arctic and sub arctic regions and SNOW cover in central and Northern Canada.

In this regard the current pattern is IDEAL. even a cursory glance at the 850 temps over the Northern Hemisphere will show http://weather.unisys.com/upper_air/ua_nhem_850.html cold air development is EXCEEDING the norm by a wide measure.

Moreover while this current pattern will bring numerous bouts of temps into the 80s and 70s into the Midwest and Ohio valley as well as the Deep South over the next 10-14 days.... having this trough over the Pacific NW and a Moderate Block over Labrador Canada will ensure a STORMY active pattern (snow cover) for central and northern Canada.

DAY 6 EURO VALID OCT 22 VALID OCT 23








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[CaptinCrunch]

you forgot the URL for the pics

http://www.wxrisk.com/meteopage.html

[farmwx]

you forgot the URL for the pics

http://www.wxrisk.com/meteopage.html

whose site is this? It is mighty arrogant ("updated, when I feel like it") what is up with that. No wonder nobody reads it..

[yoda]

you forgot the URL for the pics

http://www.wxrisk.com/meteopage.html

whose site is this? It is mighty arrogant ("updated, when I feel like it") what is up with that. No wonder nobody reads it..

Its Dave's... DT. He can be a bit arrogant... but he is a good read and is usually correct in his forecasts.

[QCWx]

you forgot the URL for the pics

http://www.wxrisk.com/meteopage.html

whose site is this? It is mighty arrogant ("updated, when I feel like it") what is up with that. No wonder nobody reads it..

Thats DT's website and EVERYBODY reads it.

[LAwxrgal]

^ Yes it's DT and he correctly predicted a couple hurricanes this year.