Huge mess this afternoon.
The GFS came in much wetter laying down 6-10 inches of snow throughout central/eastern north carolina and southern Virginia. This is after showing maybe 1-3 inches at best in the last several runs. This is in disagreement with the NAM, which shows the surface pressure remaining open and broad and the upper features remaining positively tilted as the surface feature ascends up the Atlantic coast. HPC has stated that there were some initialization errors in both models, which is not good at all this late in the game. This is due to a shortwave disturbance in South Dakota... the models have not handled this feature well. HPC suggests to use 6z and 0z data to make the forecast, which is only slightly helpful. ECMWF is not a good short term model and seems to be struggling with short term conditions.
Will have to wait until the 18z models come in to adjust my forecast, but may have to adjust to warning criteria.
Friday, December 24, 2010
Thursday, December 23, 2010
Christmas night storm update.
The latest model run show the system phasing late in the game and thus showing a weaker surface feature as well as a more eastern track.
The GFS and ECMWF are now in decent agreement with the surface features. The NAM is too suppressed.. will just throw that out for now.
Things can definitely still change... and in a dramatic way. If the system is a bit stronger and a bit closer to the coast, we could go from advisory criteria snow to a much more significant event. Will lower totals or the triangle to advisory criteria for now. Looking at an all snow event here with decent ratios should warrant at least 2 inches as of now. Will lower totals to reflect both Advisory and warning criteria potential. I may lower the totals tonight if the east trend continues but for now will just slowly taper back snow amounts. This is still a very fluid situation:
Christmas Day: A chance of snow after noon. Little or no accumulation expected
Christmas night: Snow likely. 1-4 inches of snow possible
Sunday: A chance of light snow before lunch. Little or no accumulation expected.
1-4 inches possible for the triangle.... 1-2 inches possible for Emporia
At this time a significant winter storm for the triangle is looking much less likely.
The GFS and ECMWF are now in decent agreement with the surface features. The NAM is too suppressed.. will just throw that out for now.
Things can definitely still change... and in a dramatic way. If the system is a bit stronger and a bit closer to the coast, we could go from advisory criteria snow to a much more significant event. Will lower totals or the triangle to advisory criteria for now. Looking at an all snow event here with decent ratios should warrant at least 2 inches as of now. Will lower totals to reflect both Advisory and warning criteria potential. I may lower the totals tonight if the east trend continues but for now will just slowly taper back snow amounts. This is still a very fluid situation:
Christmas Day: A chance of snow after noon. Little or no accumulation expected
Christmas night: Snow likely. 1-4 inches of snow possible
Sunday: A chance of light snow before lunch. Little or no accumulation expected.
1-4 inches possible for the triangle.... 1-2 inches possible for Emporia
At this time a significant winter storm for the triangle is looking much less likely.
Wednesday, December 22, 2010
Christmas storm update # 3
The newest GFS model came in wetter and just a bit further west.
Storm total is showing about .8 inches of total precip. Will update the forecast snowfall total if this trend continues.
Still nowhere near as strong as the ECMWF, but a major winter storm nonetheless.
Storm total is showing about .8 inches of total precip. Will update the forecast snowfall total if this trend continues.
Still nowhere near as strong as the ECMWF, but a major winter storm nonetheless.
Christmas day/night storm 2010
A significant winter storm for the Triangle is looking more likely on Christmas day through the Sunday. The 12z GFS trended closer to the ECMWF with the ECMWF holding nearly steady... just a bit further west and stronger than 00z...
HPC prefers a 50/50 blend of the GFS/ECMWF with nam being a bit of an outlier at this time, which is not unusual in the 84 hr range. Agree with HPC to mix the GFS and ECMWF despite the impressive consistency of the ECMWF... But caution tells me to not side with a historic snow storm this early. A blending of the GFS/ECMWF is a great track for heavy snow fall in the triangle... A pure ECMWF solution shows a historic bombing low just of the coast dropping warning criteria snow for a large chunk of the deep south. GFS is further east and weaker and thus most of the precip stays along the coastlines.... although GFS likely under doing precip amounts to the NW of the low.
Accumulation rates will be on high side of a 10:1 ratio due to very cold temps aloft. Am thinking that high snowfall amounts is a good possibility. But at this time will stick with only warning criteria amounts for the triangle... will hold off on higher amounts due to model discontinuity this far in advance of the low... intensity and exact location are still in question. Taking qpf literally from the from the EURO gives the Triangle 2 feet of snow with blizzard conditions lasting through Sunday night! This has the potential to not only be a strong phased storm, but a slow mover as well.
Forecast:
Christmas Day: Cold with a slight chance of snow in the afternoon.
Christmas Night: Occasional Snow... the snow could be heavy at times...
Sunday: Snow likely... the snow could be heavy at times especially in the morning... Windy with frigid temps
Sunday night: A chance of snow... windy and very cold
Monday: Decreasing clouds and very cold.
Total accumulation 3 - 7 inches possible.... May forecast higher accumulation amounts as Christmas nears.
HPC prefers a 50/50 blend of the GFS/ECMWF with nam being a bit of an outlier at this time, which is not unusual in the 84 hr range. Agree with HPC to mix the GFS and ECMWF despite the impressive consistency of the ECMWF... But caution tells me to not side with a historic snow storm this early. A blending of the GFS/ECMWF is a great track for heavy snow fall in the triangle... A pure ECMWF solution shows a historic bombing low just of the coast dropping warning criteria snow for a large chunk of the deep south. GFS is further east and weaker and thus most of the precip stays along the coastlines.... although GFS likely under doing precip amounts to the NW of the low.
Accumulation rates will be on high side of a 10:1 ratio due to very cold temps aloft. Am thinking that high snowfall amounts is a good possibility. But at this time will stick with only warning criteria amounts for the triangle... will hold off on higher amounts due to model discontinuity this far in advance of the low... intensity and exact location are still in question. Taking qpf literally from the from the EURO gives the Triangle 2 feet of snow with blizzard conditions lasting through Sunday night! This has the potential to not only be a strong phased storm, but a slow mover as well.
Forecast:
Christmas Day: Cold with a slight chance of snow in the afternoon.
Christmas Night: Occasional Snow... the snow could be heavy at times...
Sunday: Snow likely... the snow could be heavy at times especially in the morning... Windy with frigid temps
Sunday night: A chance of snow... windy and very cold
Monday: Decreasing clouds and very cold.
Total accumulation 3 - 7 inches possible.... May forecast higher accumulation amounts as Christmas nears.
Tuesday, December 21, 2010
Christmas Day Storm 2010
The GFS and ECMWF have some major difference in the amplification of the system. The GFS closes the upper low over the lakes which helps to shear out the surface low in the deep south while ECMWF has the low bombing off the carolina coast. GFS is also a bit quicker with the system, and while it is mostly slow, it does not have much precip associated with it. A 1-3 inch snowfall is likely if the GFS is correct.
The ECMWF is a historic snow storm for most of North Carolina with over a foot possible in the triangle. The historic nature of this storm makes this scenario unlikely... however... with a strong parent high in a decent location (in the northeast quadrant of the great lakes) and supporting upper level dynamics... the ECMWF is a realistic scenario. Still pretty far out in advance of this storm and a more westerly track could even mean mostly rain or ice for the triangle. If the GFS pans out then could see just a minor snow storm. The GFS does seem to be trending toward the ECMWF which has been consistent the past 2 runs. Just to stress the historic nature of the current ECMWF run. It shows about 24 hours of snow, heavy at times, with very high winds... this would be a blizzard for the triangle.
There are legit reasons to support either model run right now, therefore will not support one with confidence this early in the forecast period. Instead I will just mention the incredibly large spread in my forecast to show how difficult it can be to forecast this far out:
Christmas Day: Occasional Snow... especially after noon, but maybe moreso before noon. The snow could be heavy at times or it may stay rather light. Total accumulations of 1 to 8 inches possible
Christmas night: Snow... or no snow. Total accumulation of 0 - 12 inches possible
Sunday: Frigid with a chance of snow in the morning.. Total of accumulation of 0-3 inches possible.
Total storm accumulation of 1-23 inches possible.
Final note: At this time the HPC does favor the ECMWF model, but just a bit weaker which would still likely be a blizzard scenario for the Triangle, but not quite as historic.
The ECMWF is a historic snow storm for most of North Carolina with over a foot possible in the triangle. The historic nature of this storm makes this scenario unlikely... however... with a strong parent high in a decent location (in the northeast quadrant of the great lakes) and supporting upper level dynamics... the ECMWF is a realistic scenario. Still pretty far out in advance of this storm and a more westerly track could even mean mostly rain or ice for the triangle. If the GFS pans out then could see just a minor snow storm. The GFS does seem to be trending toward the ECMWF which has been consistent the past 2 runs. Just to stress the historic nature of the current ECMWF run. It shows about 24 hours of snow, heavy at times, with very high winds... this would be a blizzard for the triangle.
There are legit reasons to support either model run right now, therefore will not support one with confidence this early in the forecast period. Instead I will just mention the incredibly large spread in my forecast to show how difficult it can be to forecast this far out:
Christmas Day: Occasional Snow... especially after noon, but maybe moreso before noon. The snow could be heavy at times or it may stay rather light. Total accumulations of 1 to 8 inches possible
Christmas night: Snow... or no snow. Total accumulation of 0 - 12 inches possible
Sunday: Frigid with a chance of snow in the morning.. Total of accumulation of 0-3 inches possible.
Total storm accumulation of 1-23 inches possible.
Final note: At this time the HPC does favor the ECMWF model, but just a bit weaker which would still likely be a blizzard scenario for the Triangle, but not quite as historic.
Saturday, December 18, 2010
12/18 - 12/19
Still expect some mixing, but right now this could be a mostly snow event for the triangle.
Expect snow to begin around 3:00 PM and last till about 9:00 PM from SW to NE with the moderate snow ending sooner than that. Quick heavy bursts of snow have been reported in Charlotte and are possible in the triangle.
Forecast amounts of around an inch look ok for now with only around .25 inches of liquid precip expected.
Expect snow to begin around 3:00 PM and last till about 9:00 PM from SW to NE with the moderate snow ending sooner than that. Quick heavy bursts of snow have been reported in Charlotte and are possible in the triangle.
Forecast amounts of around an inch look ok for now with only around .25 inches of liquid precip expected.
Friday, December 17, 2010
12/18-12/19 Update
Just need to update the timing a bit on the precip by several hours. Am thinking precip moves in before sunset by around 2:ooPM w/ max intensity potential for snowfall will be between 7:oo and 10:00 PM and letting up around midnight.
NAM showed higher precip amounts especially between 5:00 and 9:00 PM with GFS remaining about the same.
Will keep qpf amounts the same for now.
NAM showed higher precip amounts especially between 5:00 and 9:00 PM with GFS remaining about the same.
Will keep qpf amounts the same for now.
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