Raleigh Weather Discussion
Today will be a good reminder that we are in mid-December. Temperatures will likely hold in or slowly fall through the 40s today with occasional rain showers around. This occurs as a wave of low pressure forms along a stalled out frontal boundary and moves NE off the Southeast coast today. At the same time an area of high pressure in the Northeast will keep cool air locked in at the surface. The result rain and cool temperatures through tonight.
We should dry out tomorrow with a gradual warming trend. Temps will likely be back in the 60-65 range by Friday through this weekend.
A generally more unsettled weather pattern will set up for Sunday through Tuesday as an energetic trough forms over the eastern US. We could see 2 or even 3 different storm systems form in this window. As of now, after a couple of runs of a further south solution, most of the guidance shows the storm system a rain storm for our area with the threat for snow further north over the Ohio Valley and Northeast. I think the pattern is not supportive right now of a southeast winter storm threat, so I think this will end up being a rain event for the area early next week. But I will watch it.
Cold air will likely funnel in behind this storm for mid to late next week with temperatures below normal by several degrees, certainly feeling more Christmas like.
December 19th/20th Storm Chance
After a shift south of the potential storm in this period on the models yesterday, we have seen more agreement this morning with a more Great Lakes/interior Northeast winter storm idea. I think generally the interior Northeast and Lakes are probably most at risk for a significant snow fall. I am not quite sold yet on the ECMWF idea of a widespread big snow event with even the big coastal cities getting on the action for a bit, but I am not ruling it out.
I do think areas like Pittsburgh, Syracuse, Buffalo, and much of New England look to be in pretty good position for this one as of now.
National Extended Weather Discussion
Confidence remains low in exactly what the weather pattern is going to look like for the final 1/3 of December. The GFS, GGEM, and ECMWF Ensembles show agreement in a cool pattern for the mid-Atlantic, Southeast, and western Canada. But there are some key differences and also some notable transitions in some of the forecast signals.
Both the GFS and GGEM Ensembles for several cycles now have shown building heights across the Bering Sea, Alaska, northwest and northern Canada. This would be a big change from what has been a pretty consistent pattern in the last couple of weeks of a trough/vortex across Alaska and NW Canada. This features has been defeating the –AO/-NAO signals and leading to a widespread warm pattern across the US. IF this were to break down, we may see a cooler pattern develop as the positive anomalies in Alaska/NW Canada would tend to push colder air from Canada into the US.
However, the ECMWF Ensembles do not show this ridging but maintain a trough along the west coast of Canada and into Alaska or more of the status quo. All three ensembles show a –NAO block over southern Greenland/Davis Strait retrograding into central and eastern Canada which would serve to likely keep a suppressed but probably progressive storm track across the US.
In general, we will have to just wait and see which ensemble has the best idea on the potential changes or no changes across Alaska and NW Canada. If the Euro Ensembles are right, we may see a continued generally mild pattern for much of the US. If the GGEM/GFS Ensembles are correct we could see a more widespread colder pattern develop between Christmas and New Years.
The suppressed storm track does have me intrigued a bit for the period around Christmas. WE could see some wintry chances further to the south if everything were to play out correctly. Something to watch. The MJO signal is very weak and ENSO remains neutral so it is hard to see a definitive physical forcing mechanism. The SOI has been very negative the last several days and if that continues that may have a downstream impact on the pattern with a +PNA/-EPO more favored.
Raleigh Weather Discussion
Today will be a good reminder that we are in mid-December. Temperatures will likely hold in or slowly fall through the 40s today with occasional rain showers around. This occurs as a wave of low pressure forms along a stalled out frontal boundary and moves NE off the Southeast coast today. At the same time an area of high pressure in the Northeast will keep cool air locked in at the surface. The result rain and cool temperatures through tonight.
We should dry out tomorrow with a gradual warming trend. Temps will likely be back in the 60-65 range by Friday through this weekend.
A generally more unsettled weather pattern will set up for Sunday through Tuesday as an energetic trough forms over the eastern US. We could see 2 or even 3 different storm systems form in this window. As of now, after a couple of runs of a further south solution, most of the guidance shows the storm system a rain storm for our area with the threat for snow further north over the Ohio Valley and Northeast. I think the pattern is not supportive right now of a southeast winter storm threat, so I think this will end up being a rain event for the area early next week. But I will watch it.
Cold air will likely funnel in behind this storm for mid to late next week with temperatures below normal by several degrees, certainly feeling more Christmas like.
December 19th/20th Storm Chance
After a shift south of the potential storm in this period on the models yesterday, we have seen more agreement this morning with a more Great Lakes/interior Northeast winter storm idea. I think generally the interior Northeast and Lakes are probably most at risk for a significant snow fall. I am not quite sold yet on the ECMWF idea of a widespread big snow event with even the big coastal cities getting on the action for a bit, but I am not ruling it out.
I do think areas like Pittsburgh, Syracuse, Buffalo, and much of New England look to be in pretty good position for this one as of now.
National Extended Weather Discussion
Confidence remains low in exactly what the weather pattern is going to look like for the final 1/3 of December. The GFS, GGEM, and ECMWF Ensembles show agreement in a cool pattern for the mid-Atlantic, Southeast, and western Canada. But there are some key differences and also some notable transitions in some of the forecast signals.
Both the GFS and GGEM Ensembles for several cycles now have shown building heights across the Bering Sea, Alaska, northwest and northern Canada. This would be a big change from what has been a pretty consistent pattern in the last couple of weeks of a trough/vortex across Alaska and NW Canada. This features has been defeating the –AO/-NAO signals and leading to a widespread warm pattern across the US. IF this were to break down, we may see a cooler pattern develop as the positive anomalies in Alaska/NW Canada would tend to push colder air from Canada into the US.
However, the ECMWF Ensembles do not show this ridging but maintain a trough along the west coast of Canada and into Alaska or more of the status quo. All three ensembles show a –NAO block over southern Greenland/Davis Strait retrograding into central and eastern Canada which would serve to likely keep a suppressed but probably progressive storm track across the US.
In general, we will have to just wait and see which ensemble has the best idea on the potential changes or no changes across Alaska and NW Canada. If the Euro Ensembles are right, we may see a continued generally mild pattern for much of the US. If the GGEM/GFS Ensembles are correct we could see a more widespread colder pattern develop between Christmas and New Years.
The suppressed storm track does have me intrigued a bit for the period around Christmas. WE could see some wintry chances further to the south if everything were to play out correctly. Something to watch. The MJO signal is very weak and ENSO remains neutral so it is hard to see a definitive physical forcing mechanism. The SOI has been very negative the last several days and if that continues that may have a downstream impact on the pattern with a +PNA/-EPO more favored.
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