3 Winter "events" in next 8 days for the NE CONUS?
I am not going to issue a 1st GUESS or 1st Call forecast for the system Thursday PM into early Friday morning.... primarily because the data at 0z 6a and 12z as well as most of the SREF ensembles show some serious problems. The Low develops on the TRIPLE that forms on the new Arctic front that races east across s the Midwest Thursday. The cold HIGH which EARLY Thursday morning is Over New England is sliding east off the coast...fast. Thus while we do have some WEDGE it is NOT a CAD event.
Anyone who tells you different does know their ass from a Dick Cheney
http://www.meteo.psu.edu/~gadomski/WRFEAST_12z/f21.gif
The cold air ill be a adequate for many locations in the Interior Middle Atlantic to start as snow BUT by Thursday 7pm EST the HIGH is off the coast and we have strong S winds over the Immediate East coast and over MOST of New England http://www.meteo.psu.edu/~gadomski/WRFEAST_12z/f30.gif
Inland -- say ROA CHO IAD HGR LNS ABE the low and mid level S winds will NOT be strong enough to force the warming into those areas BUT those locations will also be too far to the WEST to get any significant snow.
Key word is SIGNIFICANT snow....
In the areas that do see the heavy precip b/c of the Low's explosive development-- eastern new England --the S winds at Low and Mid levels destroy the chances of the precip falling PRIMARILY as snow. The places that see the best chance of seeing SIGNIFICANT SNOW will be CEF CON EEN and much of western ME. Once this system 35N lat by Friday morning it will go BOOM with its MSLP dropping from 1000mb to 972 MB 12 hrs later... 28 MB in 12 hrs so this is not just a boom but a BOOOOOOOOOOM!!
As I stated yesterday the really important aspect to the storm is how it sets up the conditions for the next event which will be on the the 21st into the 22nd. I am very confident now that this Triple point LOW on Friday will in fact undergo explosive development and become a huge 50/ 50 LOW over southeastern Canada this weekend and into early next week. You really have to take a look at the pressure gradient that develops on all the models Friday and Friday night ight over the eastern third of the CONUS. This is some serious CAA action being shoved into the eastern CONUS.
But also leads to problems with how the models are handling the system that comes out of Southwest. If there are 2 immutable laws about weather forecasting point is that the GFS has a serious cold bias which becomes very pronounced when you have cold air outbreaks and some sort of surface Low pressure area that tries to form on the front. The second law is that Hillary Clinton is probably a Dyke. (Okay that really does NOT have anything to do with weather forecasting but it had things to be true)... The last few runs of the OP GFS have been showing the suppressed track which we typically see in Winter systems along the East coast.
You can see from these maps the 500 MB map from the 12z WED at 96 and 108 hrs as the main short wave passing through sent Missouri then tracks over the top of the flat SE conus Ridge thru Lower OHIO...
http://www.nco.ncep.noaa.gov/pmb/nwprod/analysis/namer/gfs/12/images/gfs_500_096s.gif
http://www.nco.ncep.noaa.gov/pmb/nwprod/analysis/namer/gfs/12/images/gfs_500_108s.gif
and the 850 Low forms over the lower Midwest near or just the north of the OHIO river and tracks due East across West Virginia and then across central Virginia.
http://www.nco.ncep.noaa.gov/pmb/nwprod/analysis/namer/gfs/12/images/gfs_850_114s.gif
This should show a surface LOW which is significantly for the north then what the operational 12z WED GFS is showing.
Of course the model is not going to show that at this time range because if ever there was a pattern which would trigger the GFS cold bias to manifest itself well this is a pattern that's going to show it. In fact I would of been shocked IF the GFS had NOT showed a more suppressed flat track off the North Carolina coast at this time range. We can also see from this next map that the position of the Southern low at 108 and 114 hours is significantly too far to the South and east almost over the far sw corner of GA... which makes no sense given the overall synoptic pattern.
http://www.nco.ncep.noaa.gov/pmb/nwprod/analysis/namer/gfs/12/images/gfs_slp_108s.gif
http://www.nco.ncep.noaa.gov/pmb/nwprod/analysis/namer/gfs/12/images/gfs_slp_114s.gif
Even so from that point the model takes the system ENE then once the Low reaches the latitude 34N it turns it sharply to the east. Thus one of the things that the operational GFS might be missing here is the flat Ridge over the Southeast. Behind this system comes more very cold air... and the potential for a more significant winter storm sometime around January 25 --26.
The 0z run of the European you can see here takes and other strong /w which drops down over the top the Ridge into New Mexico and far southwestern Texas and phases it with the next strong Arctic shortwave dropping in on the PJ across the Great Lakes. This results in a major storming off the Southeast coast and threatening the Mid Atlantic and New England areas while with a major snowstorm. The 12z GFS does not show this because it takes the s/w that drops in over western Texas and close it off over the Southwest with the operational run showing the 500 Low RETROGRADING off the Southern California coast at 168 -192 hrs. Thus the operational 12z GFS only has the strong northern shortwave and the cold front --- Manitoba Mauler type Clipper diving across the Great Lakes with note the Southern system to face with.
The Midday 12z WED euro is fairly consistent with the 0z run but because it hangs back the energy over the Southwest states a little longer -- again a common bias of the European model-- the phases is not as direct as what we saw on the 0z run and as a result the system takes already organizing makes a wide turn off the Southeast coast at 204 hrs . It's still a significant threat and one should not overreact to the what the 12z WED European model is showing is at 8.5 days out in time. There is very little support from the 12 see GFS ensembles for the European big storm scenario per se but on the other hand only 2 of the 11 members of the 12z GFS ensembles shows a closed 500 low retrograding back into California.
Lastly12z 8-10 day 500 mean shows that BOTH s the operational European and it now the operational GFS a -NAO REX block developing in the area between southeastern Greenland and Ireland. This is assuming that the models are correct would indeed count as a strong - NAO Block.
http://www.meteo.psu.edu/~gadomski/ECMWF_12z/hgtcomp.html
more later
Anyone who tells you different does know their ass from a Dick Cheney
http://www.meteo.psu.edu/~gadomski/WRFEAST_12z/f21.gif
The cold air ill be a adequate for many locations in the Interior Middle Atlantic to start as snow BUT by Thursday 7pm EST the HIGH is off the coast and we have strong S winds over the Immediate East coast and over MOST of New England http://www.meteo.psu.edu/~gadomski/WRFEAST_12z/f30.gif
Inland -- say ROA CHO IAD HGR LNS ABE the low and mid level S winds will NOT be strong enough to force the warming into those areas BUT those locations will also be too far to the WEST to get any significant snow.
Key word is SIGNIFICANT snow....
In the areas that do see the heavy precip b/c of the Low's explosive development-- eastern new England --the S winds at Low and Mid levels destroy the chances of the precip falling PRIMARILY as snow. The places that see the best chance of seeing SIGNIFICANT SNOW will be CEF CON EEN and much of western ME. Once this system 35N lat by Friday morning it will go BOOM with its MSLP dropping from 1000mb to 972 MB 12 hrs later... 28 MB in 12 hrs so this is not just a boom but a BOOOOOOOOOOM!!
As I stated yesterday the really important aspect to the storm is how it sets up the conditions for the next event which will be on the the 21st into the 22nd. I am very confident now that this Triple point LOW on Friday will in fact undergo explosive development and become a huge 50/ 50 LOW over southeastern Canada this weekend and into early next week. You really have to take a look at the pressure gradient that develops on all the models Friday and Friday night ight over the eastern third of the CONUS. This is some serious CAA action being shoved into the eastern CONUS.
But also leads to problems with how the models are handling the system that comes out of Southwest. If there are 2 immutable laws about weather forecasting point is that the GFS has a serious cold bias which becomes very pronounced when you have cold air outbreaks and some sort of surface Low pressure area that tries to form on the front. The second law is that Hillary Clinton is probably a Dyke. (Okay that really does NOT have anything to do with weather forecasting but it had things to be true)... The last few runs of the OP GFS have been showing the suppressed track which we typically see in Winter systems along the East coast.
You can see from these maps the 500 MB map from the 12z WED at 96 and 108 hrs as the main short wave passing through sent Missouri then tracks over the top of the flat SE conus Ridge thru Lower OHIO...
http://www.nco.ncep.noaa.gov/pmb/nwprod/analysis/namer/gfs/12/images/gfs_500_096s.gif
http://www.nco.ncep.noaa.gov/pmb/nwprod/analysis/namer/gfs/12/images/gfs_500_108s.gif
and the 850 Low forms over the lower Midwest near or just the north of the OHIO river and tracks due East across West Virginia and then across central Virginia.
http://www.nco.ncep.noaa.gov/pmb/nwprod/analysis/namer/gfs/12/images/gfs_850_114s.gif
This should show a surface LOW which is significantly for the north then what the operational 12z WED GFS is showing.
Of course the model is not going to show that at this time range because if ever there was a pattern which would trigger the GFS cold bias to manifest itself well this is a pattern that's going to show it. In fact I would of been shocked IF the GFS had NOT showed a more suppressed flat track off the North Carolina coast at this time range. We can also see from this next map that the position of the Southern low at 108 and 114 hours is significantly too far to the South and east almost over the far sw corner of GA... which makes no sense given the overall synoptic pattern.
http://www.nco.ncep.noaa.gov/pmb/nwprod/analysis/namer/gfs/12/images/gfs_slp_108s.gif
http://www.nco.ncep.noaa.gov/pmb/nwprod/analysis/namer/gfs/12/images/gfs_slp_114s.gif
Even so from that point the model takes the system ENE then once the Low reaches the latitude 34N it turns it sharply to the east. Thus one of the things that the operational GFS might be missing here is the flat Ridge over the Southeast. Behind this system comes more very cold air... and the potential for a more significant winter storm sometime around January 25 --26.
The 0z run of the European you can see here takes and other strong /w which drops down over the top the Ridge into New Mexico and far southwestern Texas and phases it with the next strong Arctic shortwave dropping in on the PJ across the Great Lakes. This results in a major storming off the Southeast coast and threatening the Mid Atlantic and New England areas while with a major snowstorm. The 12z GFS does not show this because it takes the s/w that drops in over western Texas and close it off over the Southwest with the operational run showing the 500 Low RETROGRADING off the Southern California coast at 168 -192 hrs. Thus the operational 12z GFS only has the strong northern shortwave and the cold front --- Manitoba Mauler type Clipper diving across the Great Lakes with note the Southern system to face with.
The Midday 12z WED euro is fairly consistent with the 0z run but because it hangs back the energy over the Southwest states a little longer -- again a common bias of the European model-- the phases is not as direct as what we saw on the 0z run and as a result the system takes already organizing makes a wide turn off the Southeast coast at 204 hrs . It's still a significant threat and one should not overreact to the what the 12z WED European model is showing is at 8.5 days out in time. There is very little support from the 12 see GFS ensembles for the European big storm scenario per se but on the other hand only 2 of the 11 members of the 12z GFS ensembles shows a closed 500 low retrograding back into California.
Lastly12z 8-10 day 500 mean shows that BOTH s the operational European and it now the operational GFS a -NAO REX block developing in the area between southeastern Greenland and Ireland. This is assuming that the models are correct would indeed count as a strong - NAO Block.
http://www.meteo.psu.edu/~gadomski/ECMWF_12z/hgtcomp.html
more later
posted by DT @ 1/17/2007 04:08:00 PM
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