Maps and Charts
Keeping An Eye On the Weekend
Thursday February 4, 2010 07:14 AM
Thursday Update: Questions still remain as to just how far north the weekend storm will progress. As has been the case for much of the last month, an atmospheric traffic jam is going to block the Mid-Atlantic storm from driving too far up the coast and instead force it to make a right hand turn eastward out to sea well south of Cape Cod.
However, just subtle changes in the upper level pattern and the eventual placement of the storm will make a world of difference for the Cape and Island. There is still room for this storm to tick northward a hair and this could put us in the northernmost snow shield for a time. For now, odds favor just a grazing scenario with some light snows and flurries - but things can change!
Wednesday Update: All eyes are squarely (roundly?) on the weekend forecast. A strong low pressure system will track up the coast and position itself east of the Mid-Atlantic Friday. From there, the storm will begin to turn right, heading eastward parallel to the south coast of New England; but the big question is just where (at what latitude) this turn takes place. This will be dictated mostly by the strength and position of a "polar vortex" positioned to the north of New England (a semi-permanent feature this winter season).
Should the turn occur early, the northern extent of the snow shield will only graze Cape Cod, giving us cloudy skies with some snow flurries or some periods of light snow. However, should the system tuck in closer to the coast and shift a bit further north before heading out to sea, we would be under-the-gun for a period of strong northeast winds and plowable snows.
The early money is on the latter scenario verifying, with the storm's shield of snow overspreading most, if not all, of Southern New England and delivering a sizable snowfall to CT/RI and Southeast MA/Cape Cod. Check back for updates.
Tuesday's Forecast: A generally quiet and chilly stretch of weather lies ahead of us as a dry northwest flow of air persists through most of the upcoming workweek. A small weather system will slide by the region later tonight and Wednesday, bringing some clouds and periodic flurries and light snow showers, but otherwise a storm-free week is expected. Looking ahead to next weekend, there are signs that our quiet weather may come to a screeching halt.
A storm system developing over the northern Gulf of Mexico later this week will head northeastward and pass near the North Carolina coastline by Friday night. From there, the storm will lift north and eastward toward the Mid-Atlantic, possibly deepening into a powerful coastal storm as strong jet stream energy tries to feed into the developing low pressure center.
Where the storm tracks from the southern Mid-Atlantic coastline will have major implications on our weekend weather. Should a blocking pattern currently in place over Canada and Greenland relax enough, the storm will have "room" to lift far enough northward to impact us with a period of snow and strong winds. However, should the upper level winds remain locked up, the system will likely shift eastward out to sea well south and east of Cape Cod, keeping the brunt of the bad weather offshore.
Given this storm is still 4 to 5 days away, it is nearly impossible to know with much certainty how the pattern will evolve. Consequently, check back for updates over the next few days as the event draws nearer and the details become more discernible. This image, provided courtesy of Stormvista, shows the European computer model's interpretation of the weekend storm. Notice the system is just grazing the south coast of New England on this particular chart.
Comments
Hi Steve,
I'm not sure I understand your question.
NAM:
www.nco.ncep.noaa.gov/pmb/nwprod/analysis/namer/nam/06/images/nam_pcp_072m.gif
GFS:
www.nco.ncep.noaa.gov/pmb/nwprod/analysis/namer/gfs/06/images/gfs_pcp_066m.gif
The GFS is a bit more favorable. Will be interesting to watch the model runs come in over the next couple of days.
Steve,
By the "ADDS" are you referring to the Aviation Digital Data Service?
The NAM is best inside of 60 hours. GFS runs out to 16 days but really is only worthwhile inside of 5 (and some would argue not even that far). Hands down the best tool out there is the ECMWF. For a global model it has extremely high resolution and the physics of the model make it top notch.