Browse Year

2011

What to Watch Fore(cast) – Jan 3-10

Highlights:

Another snow storm in the Northeast? – Guidance hints at a small winter storm impacting the Northeast this weekend.

Snow potential in the Southeast – Two systems, one during mid-week and one at the start of next week, both have the potential to bring snow to the Southeast.

Here comes the cold! – The start of next week will be the beginning of a deep cold period across most of the U.S.

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Discussion:

None this week… sorry! Way too much going on at the moment.

Mid-Atlantic – The Week Ahead (Jan 2-9)

We start the new year with a mild and wet couple of days, but a dry and somewhat near-normal temperature pattern will move in place of it through most of the week. Behind the cold front that recently passed through the region, skies will become mostly clear through Wednesday.

A low pressure system diving in from the Great Lakes will bring us a chance of rain/snow showers Friday morning through early Saturday, but it will be hard to get more than 1-2 inches of snow east of the Appalachians, with light snow/rain working as far south as central Virginia and southern Maryland. Areas further north (PA/NJ) and the western side of the Appalachians could see 2-4″ of snow from this system, with locally higher amounts. I’ll post an update for this storm as the time gets closer.

Following this system, we will see windy conditions and lake-effect snow on the windward side of the mountains Saturday and Sunday. We will return to below normal temperatures, much like what we saw at the start of last week. More cold and dry weather is in our future as we go into the second week of January.

A much colder January than you might expect!

As the first half of January comes into better focus, it appears that the blocking pattern over the Atlantic which has allowed the eastern half of the U.S. to be so cold in December will be making a comeback for a good part of January, which means another round of cold weather (but perhaps not as cold as December in the eastern half of the U.S.).

The forecast made by me (and made similarly by many others before December) argues for a more typical La Niña January, which calls for above normal temperatures through most of the country. However, typical La Niñas do not feature a large blocking pattern over the Atlantic, which prevents storms from progressing eastwards over the Atlantic Ocean. Instead, these storm systems retrograde, or move westwards, across Canada. The result is a greater northwesterly flow across North America, which, coupled with cold air from Siberia and western Canada, brings deep cold all the way down into the Southeast U.S. Conversely, the flow of maritime air from the Atlantic into eastern Canada results in above normal temperatures in that region.

What will be different this time around is the weather pattern in the West, which favors more storm systems digging southward along the West Coast as opposed to diving in west of the Rockies. The result will draw the below normal temperatures into most of the West as the upper-level energy travels across the southern U.S. The flow coming out of the mid-continent will suppress these storms and keep them further south than what would normally happen if there was no blocking pattern. Should the blocking pattern relax, these storm systems would be able to run northeast in the eastern U.S., which would bring the return of near normal to above normal temperatures to the East.

The result of the January weather pattern would be below normal temperatures for nearly the whole U.S., but the cold will at least be less dramatic in the eastern U.S. as was seen in December, which had a much more meridional flow with above normal temperatures in the western U.S.

If we were to keep this blocking pattern for most of January, this is what we could be looking at with respect to temperature:


Risks:
– Warmer West
– Warmer Southeast/Mid-Atlantic
– Colder mid-country/Southeast
– Warmer Great Lakes/Northeast

Did I just say the Southeast had warmer AND colder risks? I most certainly did. Why? Because with more storm systems digging into the West, we could see them lift north more quickly as they work into the Southeast. This goes for the Mid-Atlantic as well. Conversely, if the blocking pattern we get is stronger than expected, the deep cold would be able to work farther into the Southeast.

Starting this week – The weekly severe weather review

Not sure what day I’ll put it up on… perhaps Friday. The idea is to look back at the previous week’s severe weather and highlight the most interesting stuff. I’ll start it this week.

The Week Ahead forecast for the Mid-Atlantic will be coming later today! Some interesting stuff planned, including a broader look into temps for the rest of January.