Lots to talk about this early evening so let’s get right to it.  First as I’m sure youwill see shortly… I have changed and updated the December 2009 forecast.  I explained in the earlier post why I am doing this but I am sure some are going to raise questions for my comments so let me go over this one more time.

 

 Some of you folks have really got to stop looking at just the surface map to see what a big L is located. at 102 and 120 hrs that is NOT what is important. the area that has the best chance to see the best snows from this Low will be portions of the Ohio Valley and the eastern Great Lakes. For the entire East Coast this is purely a rainy that but as the low moves across the Appalachians to the northeast coast some of the precipitation over the higher terrain of PA and western and central NYstate and northern New England will change over snow and several inches are possible 12/3-12/4.

Ok now once we get past 12/4 and  the Big Low is now up in southeast Canada the Arctic air finally reaches the East Coast by 12/5.

The 12z 11/28 European model to show the threat off the southeast coast at day 7. Lets take a look at that for a second. Note as you can see on this image from the European site I have highlighted with a red line the southern short wave which is moving through the southeastern states. It should be noted that the tilt is negative which of course implies development and that is in fact what we see happen at 180 and 192 hrs…. but the lowest too far off the coast to coast the s/w trough develops the negative tilt too late… is too far to the east.

On the other hand if we look at the pattern a day 10 we can see another attempt by the model to phase the two streams with a significant short wave over western TX and OK and a s/w in the PJ dropping into the western Plains. The models implication here is clear that any sort of surface low development over Texas would track ENE or NE and climb much further off the coast. This sort of pattern could set the stage for a possible significant winter weather threat for portions of the Ohio Valley/ Lower Midweast and the Northeast 12/9 and 12/10.

  Taking a look at the day 10 ECMWF   MODEL  hemispheric shot we can see several important features. And I have highlighted them…

 
Feature A is the development of a huge large vortex of the North Pacific Ocean. If this feature stays where it is and does not progress to the east… a cold pattern over the central/ eastern US will hold. On the other hand if this huge 500 Low / Vortex in the northern Pacific does move east… a +EPO than the cold pattern will collapse.

FEATURE B is a block which has developed over the Bering Sea. This blocking High/ Ridge was originally part of the top of the ridge that was a Western Canada at day 6 and 7. The European model is saying that the Pacific jet is going to undercut it… and as it does so it will allow the block to retrograde back towards the Bering Sea.

FEATURE C… is a very intense poll for tax which is centered almost exactly over the North Pole. This vortex appears to have come over from Siberia… and represents the heart of the Arctic air. Where this featured propagates to next is anyone’s guess.

FEATURE D appears to be the development of a easten based -NAO… one that is east of Iceland and close tom the UK.

This last feature is of particular importance. The 12z 240 and 300 hrs GFS ensembles clearly show that this eastern based – NAO may be expanding or retrograde to the West… that is towards GREENLAND…. which can be seen here….

    

  This trend with these weather models will have to you watched over the next several days to see whether not this is just a glitch or whether a real trend.

 

 

 

  

The second big issue that has to be raised here in forecasting what a first half in December 2009 is going to look like… has to do with the overall recent model performance. Early next week is going to be a significant Low that will form over the Delta and track towards the Great Lakes . Again as I said above this is nothing new and has been the pattern since September    My point here is that if you go back and take a look at the GFS and the GFS ensembles from last week– NOV 14-20 there was absolutely no hint at all of this sort of significant feature developing. The GFS in the GFS ensemble did NOT show a sharp deep trough developing over the Plains….  they did NOT show a significant Low developing over the Delta tracking into the Great Lakes… they did NOT show a possible significant snowstorm over the western portions of the lower Plains (TX Panhandle much of OK KS ) and much of and into the western portions of the upper Mississippi Valley ( western MO IA western WI MN) .

Instead what we saw was run after run on the GFS in the GFS ensembles showing large-scale pretty serious looking cold air outbreaks with 850 temps of -10c and -15c pushing fairly far to the south across the central Plains into the middle Atlantic states. The models had no hint at all of the significant Delta to Great Lakes low forming 11/20 -12/1.

NONE.

Of course I am not expecting to see perfect accuracy on the GFS or GFS ensemble… the European or the European ensemble… the Canadian or the Canadian ensemble 10 days+ but some of the members at some point should have latched onto this Low and for the most part they really did not.

This feature is kind of important since not only was it completely missed in the 11-15 day forecast models and ensemble from last week… but how this Low develops is going to greatly determine where the cold air is going to come in first over the Plains and Midwest…. and how much of the cold air is going to make it into the Northeast in early December.

Yesterday all of the model data was depicting this Delta Low as a major Low from Louisiana into the Great Lakes on 11/30 and 12/1 but there is some uncertainty about this idea based upon the 0z Wed model data. The European model shows this Low coming out in bits and pieces as opposed to one big giant Low moving to the Gulf coast up to the Great Lakes. If the European model is corrected there could be some snow over the Oklahoma and Texas Panhandle 11/30 but it would not be a major event.

On the other hand the GFS model still very bullish with the system . It devlops a Major Low over the Delta that develops rapidly into a significant system as it heads towards the Great Lakes. This sort of track and its deep closed 500 Low over OK would set the stage for another significant early-season snow but this time instead of being over eastern Colorado Western Kansas… the snow would fall over the Texas Panhandle and much of OK and KS on 11/30. The 0z and 6z GFS also show a fairly large cold High situated over the eastern Rockies that would provide low-level cold air and set up the potential for significant snow in the lower Plains on the 30th. If the GFS solution is right they significant snow area would also move into MO IA MN and WI on 12/1. The GFS solution is also supported by the early-morning Canadian as well as the British model.

Behind the system the GFS shows a significant outbreak of cold air for the first time this season across the Plains and the Midwest which eventually moves into the East Coast. The European model agrees but this model has the heart of cold air further to the west centered over the Plains and the Rockies and over the WCB.

The next issue obviously we have to start talking about is how long does the cold pattern last? If you’re convinced or you really think that the December 2009 is going to be as cold as December 2000…. and /or one of the top 10 cold as Decembers and my advice to use stop reading right now.

In order for such an extreme situation to develop… be at December January February March… you have to have a heart of the cold air on this side of the world. Right now you can see the main Polar Ortex (PV) is still situated way over and China and Siberia. There is no hint that any the model data that I have seen this morning that the vortex is going to leave and shift over into the Western Hemisphere in the 11-15 day. And without the vortex setting up in the Western Hemisphere presumably over central / eastern Canada is no way to keep the cold pattern in place. Without having a PV in place there is no resistance when the pattern begins to break down and Pacific jet once again reassert itself.

One last point… it is of course possible to have several PVs across the northern hemisphere during the winter months. It is not a case of having only one PV. So I suppose it is possible that in the 11-15 day or beyond we may see a PV developed over central and eastern Canada at some point. But that’s an awful long way off and so far were not seeing any hint of that sort of development on any of the models.

In earlier post I discussed how the ALL of the models in Mid NOV   missed the significance of this major and first BIG winter storm of the season for the eastern US.    As we get them closer to the event we can see a lot more Model consistency; but once again we continue to see snow enthusiasts and overzealous forecasters attempt to find some possible way to bring the Low of the Coast and bring some sort of snow into the forecast even over the interior Northeast.

This is simply not going to happen and it’s obvious from the synoptic pattern at 500 MB why. The 11/28 12z GFS at 102 hrs shows is quite clearly. We can see two distinct pieces of energy…one over the Upper Plains and the big southern closed Low over the Delta. This is waaaaay too far to the west to allow for some sort of phasing that’s going to benefit the East Coast. Finally after being much further east than any other model the 12z GFS FINALLY got a clue and shifted to the west with the system tracking through the spine of the lower and central Appalachians.

Some of you folks have really got to stop looking at just the surface map to see what a big L is located. at 102 and 120 hrs that is NOT what is important. the area that has the best chance to see the best snows from this Low will be portions of the Ohio Valley and the eastern Great Lakes. For the entire East Coast this is purely a rainy that but as the low moves across the Appalachians to the northeast coast some of the precipitation over the higher terrain of PA and western and central NYstate and northern New England will change over snow and several inches are possible 12/3-12/4.

Ok now once we get past 12/4 and acted below is now up in southeast Canada the Arctic air finally reaches the East Coast by 12/5.

The 12z 11/28 European model to show the threat off the southeast coast at day 7. Lets take a look at that for a second. Note as you can see on this image from the European site I have highlighted with a red line the southern short wave which is moving through the southeastern states. It should be noted that the tilt is negative which of course implies development and that is in fact what we see happen at 180 and 192 hrs…. but the lowest too far off the coast to coast the s/w trough develops the negative tilt too late… is too far to the east.

On the other hand if we look at the pattern a day 10 we can see another attempt by the model to phase the two streams with a significant short wave over western TX and OK and a s/w in the PJ dropping into the western Plains. The models implication here is clear that any sort of surface low development over Texas would track ENE or NE and climb much further off the coast. This sort of pattern could set the stage for a possible significant winter weather threat for portions of the Ohio Valley/ Lower Midweast and the Northeast 12/9 and 12/10.

Taking a look at the day 10 hemispheric shot we can see several important features. And I have highlighted them… Feature A is the development of a huge large vortex of the North Pacific Ocean. If this feature stays where it is and does not progress to the east… a cold pattern over the central/ eastern US will hold. On the other hand if this huge 500 Low / Vortex in the northern Pacific does move east… a +EPO than the cold pattern will collapse.

FEATURE B is a block which has developed over the Bering Sea. This blocking High/ Ridge was originally part of the top of the ridge that was a Western Canada at day 6 and 7. The European model is saying that the Pacific jet is going to undercut it… and as it does so it will allow the block to retrograde back towards the Bering Sea.

FEATURE C… is a very intense poll for tax which is centered almost exactly over the North Pole. This vortex appears to have come over from Siberia… and represents the heart of the Arctic air. Where this featured propagates to next is anyone’s guess.

FEATURE D appears to be the development of a easten based -NAO… one that is east of Iceland and close tom the UK.

This last feature is of particular importance. The 12z 240 and 300 hrs GFS ensembles clearly show that this eastern based – NAO may be expanding or retrograde to the West… that is towards GREENLAND…. which can be seen here….

This trend with these weather models will have to you watched over the next several days to see whether not this is just a glitch or whether a real trend.

This is simply not going to happen and it’s obvious from the synoptic pattern at 500 MB why. The 11/28 12z GFS at 102 hrs shows is quite clearly. We can see two distinct pieces of energy…one over the Upper Plains and the big southern closed Low over the Delta. This is waaaaay too far to the west to allow for some sort of phasing that’s going to benefit the East Coast. Finally after being much further east than any other model the 12z GFS FINALLY got a clue and shifted to the west with the system tracking through the spine of the lower and central Appalachians.

Some of you folks have really got to stop looking at just the surface map to see what a big L is located. at 102 and 120 hrs that is NOT what is important. the area that has the best chance to see the best snows from this Low will be portions of the Ohio Valley and the eastern Great Lakes. For the entire East Coast this is purely a rainy that but as the low moves across the Appalachians to the northeast coast some of the precipitation over the higher terrain of PA and western and central NYstate and northern New England will change over snow and several inches are possible 12/3-12/4.

Ok now once we get past 12/4 and acted below is now up in southeast Canada the Arctic air finally reaches the East Coast by 12/5.

The 12z 11/28 European model to show the threat off the southeast coast at day 7. Lets take a look at that for a second. Note as you can see on this image from the European site I have highlighted with a red line the southern short wave which is moving through the southeastern states. It should be noted that the tilt is negative which of course implies development and that is in fact what we see happen at 180 and 192 hrs…. but the lowest too far off the coast to coast the s/w trough develops the negative tilt too late… is too far to the east.

On the other hand if we look at the pattern a day 10 we can see another attempt by the model to phase the two streams with a significant short wave over western TX and OK and a s/w in the PJ dropping into the western Plains. The models implication here is clear that any sort of surface low development over Texas would track ENE or NE and climb much further off the coast. This sort of pattern could set the stage for a possible significant winter weather threat for portions of the Ohio Valley/ Lower Midweast and the Northeast 12/9 and 12/10.

Taking a look at the day 10 hemispheric shot we can see several important features. And I have highlighted them… Feature A is the development of a huge large vortex of the North Pacific Ocean. If this feature stays where it is and does not progress to the east… a cold pattern over the central/ eastern US will hold. On the other hand if this huge 500 Low / Vortex in the northern Pacific does move east… a +EPO than the cold pattern will collapse.

FEATURE B is a block which has developed over the Bering Sea. This blocking High/ Ridge was originally part of the top of the ridge that was a Western Canada at day 6 and 7. The European model is saying that the Pacific jet is going to undercut it… and as it does so it will allow the block to retrograde back towards the Bering Sea.

FEATURE C… is a very intense poll for tax which is centered almost exactly over the North Pole. This vortex appears to have come over from Siberia… and represents the heart of the Arctic air. Where this featured propagates to next is anyone’s guess.

FEATURE D appears to be the development of a easten based -NAO… one that is east of Iceland and close tom the UK.

This last feature is of particular importance. The 12z 240 and 300 hrs GFS ensembles clearly show that this eastern based – NAO may be expanding or retrograde to the West… that is towards GREENLAND…. which can be seen here….

This trend with these weather models will have to you watched over the next several days to see whether not this is just a glitch or whether a real trend.

This is simply not going to happen and it’s obvious from the synoptic pattern at 500 MB why. The 11/28 12z GFS at 102 hrs shows is quite clearly. We can see two distinct pieces of energy…one over the Upper Plains and the big southern closed Low over the Delta. This is waaaaay too far to the west to allow for some sort of phasing that’s going to benefit the East Coast. Finally after being much further east than any other model the 12z GFS FINALLY got a clue and shifted to the west with the system tracking through the spine of the lower and central Appalachians.

Some of you folks have really got to stop looking at just the surface map to see what a big L is located. at 102 and 120 hrs that is NOT what is important. the area that has the best chance to see the best snows from this Low will be portions of the Ohio Valley and the eastern Great Lakes. For the entire East Coast this is purely a rainy that but as the low moves across the Appalachians to the northeast coast some of the precipitation over the higher terrain of PA and western and central NYstate and northern New England will change over snow and several inches are possible 12/3-12/4.

Ok now once we get past 12/4 and acted below is now up in southeast Canada the Arctic air finally reaches the East Coast by 12/5.

The 12z 11/28 European model to show the threat off the southeast coast at day 7. Lets take a look at that for a second. Note as you can see on this image from the European site I have highlighted with a red line the southern short wave which is moving through the southeastern states. It should be noted that the tilt is negative which of course implies development and that is in fact what we see happen at 180 and 192 hrs…. but the lowest too far off the coast to coast the s/w trough develops the negative tilt too late… is too far to the east.

On the other hand if we look at the pattern a day 10 we can see another attempt by the model to phase the two streams with a significant short wave over western TX and OK and a s/w in the PJ dropping into the western Plains. The models implication here is clear that any sort of surface low development over Texas would track ENE or NE and climb much further off the coast. This sort of pattern could set the stage for a possible significant winter weather threat for portions of the Ohio Valley/ Lower Midweast and the Northeast 12/9 and 12/10.

Taking a look at the day 10 hemispheric shot we can see several important features. And I have highlighted them… Feature A is the development of a huge large vortex of the North Pacific Ocean. If this feature stays where it is and does not progress to the east… a cold pattern over the central/ eastern US will hold. On the other hand if this huge 500 Low / Vortex in the northern Pacific does move east… a +EPO than the cold pattern will collapse.

FEATURE B is a block which has developed over the Bering Sea. This blocking High/ Ridge was originally part of the top of the ridge that was a Western Canada at day 6 and 7. The European model is saying that the Pacific jet is going to undercut it… and as it does so it will allow the block to retrograde back towards the Bering Sea.

FEATURE C… is a very intense poll for tax which is centered almost exactly over the North Pole. This vortex appears to have come over from Siberia… and represents the heart of the Arctic air. Where this featured propagates to next is anyone’s guess.

FEATURE D appears to be the development of a easten based -NAO… one that is east of Iceland and close tom the UK.

This last feature is of particular importance. The 12z 240 and 300 hrs GFS ensembles clearly show that this eastern based – NAO may be expanding or retrograde to the West… that is towards GREENLAND…. which can be seen here….

This trend with these weather models will have to you watched over the next several days to see whether not this is just a glitch or whether a real trend.

 

 

 However you can see from the new UKMET forecast the entire MJO impulse now completely collapses and turns inward into the neutral circle — which is something I’ve been arguing about for the past 7+ days! While some may be surprised about the sudden shift in the MJO I am not.

 

 

 

Fear not however for those who wish to-monger about the cold and the snow along with Christmas threat of widespread snows and DEC 200 analogs… I am sure it will be something else you can latch onto in the coming days.

 ==============================

 

 

 11/20/09 0920 EST

We are reaching a critical phase in the  MJO track.  Several times over the past to three months when the NGO has moved into phase 3 or 4  it has collapsed and has not moved into the more favorable  — WHICH  for the eastern conus   –Phase 7 and 8.

Here is the CURRENT   track of the MJO

AS  WE CAN  see from the various models such as the   GFS  and   what happens next is quite uncertain.

The   CAR   shows the current MJO sweeping through  Phase  4 5  and into  6.

 but the  GFS and GFS ensemble mean completely collapse the MJO  and forces it back into the neutral area or no reading  circle
which has been the trend so far this Autumn.

 

And finally the UKIE    does keep the  MJO  alive … in a somewhat weakened state and progress at all way through the phase 7 by the end of the month which would support a significant shift towards a colder pattern.

If the MJO collapses and turns it into the neutral zone which would happen several times this autumn then the forecast for the colder December pattern developing is going to bust.   On the other hand if the UKMET   happens to be correct then I am going to bust.

Last week I talked about the current MJO feature and how it was forecasted to track through the regions 3 and 4 of the MJO cycle but then forecasted to come to a screeching halt and die when they reached area 5 or 6. In case you have forgotten the MJO is a weather event which occurs along the equatorial Pacific running from Indonesia towards the international dateline. Essentially the MJO is a large area of convection which develops over Indonesia and as it moves east along the equatorial Pacific… it sends out ways of energy into the northern latitudes in the Pacific Ocean which causes the pattern with the jet stream to shift.

Different phases of the MJO correlate to different weather patterns over North America. For the past 4 months the MJO has not been able to get out of area 4 without collapsing… and thus we’ve been pretty much in the same pattern … one that features a constant stream of Pacific energy bringing in numerous weather systems — which is why September and October 2009 when the two wettest autumn months on record for much of the planes in the Midwest.

All last week the various weather models which I use to forecast the MJO showed that the MJO was either going to stall or collapse and die before it reached areas 5 and 6. This is important because when the MJO moves into areas 7 8 on the MJO track it correlates to a much colder pattern for much of the central and eastern CONUS . Thus if in fact the MJO did stall or collapse the cold pattern coming into the Plains and Midwest and eventually the Northeast were only last a few days.

The data on Thursday and early this morning shows that the MJO did NOT stall. It did not weaken. In fact if anything the MJO increased its intensity and continue to sweep through area 6 heading for area 7 and 8. This greatly increases the probability that the colder pattern is going to last longer and that it is going to represent a significant change in a mild October pattern.

The implications of this are quite profound with respect to my December 2009 forecast. And I will deal with that in a separate entry shortly but the basic argument is that my initial preliminary Winter 2009-10 forecasts — which was a continuation of the September October patterns with respect to temperatures and precipitation appears to have been the right one and I probably should not have changed it. In my defense however I do have to admit that when Neil Niño started surging in its intensity and temperature anomalies in late October and November to believe that it would fundamentally affect the pattern for the winter months… especially for December.

Since my December 2009 forecast called for such warm conditions across so much of the nation… the initial cold shot that comes through behind this Ohio Valley/ Appalachian Low combined with the fact that the MJO is going to track through quadrant 7 and 8… spells doom for my December 2009 forecast even before it begins.

These large-scale hemispheric maps show the persistent pattern we’ve seen over the last several days across the north central Atlantic. We can see that the Iceland will has been exceptionally intense over the past week… which in part manifestation of the positive phase of the NAO.(11/11/09).

 

 

 

 

As you can see in this current large-scale hemispheric shot another strong impulse was moved out of the Iceland low position and underwent explosive intensification over the last 24 hours as the Vort max embedded in the intense 500 Low developed a negative tilt.

The 12z Sunday GFS shows another massive system passing to the North West of Scotland on Tuesday at 960 mb… which dawdles or lingers across the North Sea on Wednesday 11/25…

 

The system for Wednesday is somewhat supported by the 12z Sunday European model But the Euro has the massive Low significantly further to the north. The third system for this weekend is actually being handled rather consistently between the European and the GFS model as a both show a Low some are around 975 MB over Northern Ireland/ Scotland.

 

This event should be followed rather closely and local forecasts and media coverage as these systems could do a lot of damage to the southeast coast of Norway as well as the western coast of Scotland Ireland and the Highlands were heavy snow could fall.