Plain-language summary:
After unusually dry weather with seasonable
temperatures, finally with more sunshine, through Friday. It turns cloudier and
much milder with light rain next weekend before it gradually turns colder
afterward with a potential snowstorm around February 12 and 13. The weather
pattern starting mid-February looks markedly colder with potential for Nor’easters,
though it could also be relatively dry with the storms developing too late or
remaining too far offshore for our region.
Meteorological discussion:
A pronounced vertically stacked ridge
(Omega block) developed over central Canada in late January, classic of a
strong El Nino, but it was extreme even for an El Nino, with all-time January record
highs being set. That ridge to the west has led to persistent dry deep northwesterly
flow across our region, shoving any storm well to the south and east, but also
featuring a persistent low-level inversion with low-level moisture and clouds
trapped underneath, leading to an incredibly cloudy January. However, the subsidence
associated with the ridge is finally drying out the low-levels, allowing
clearer skies to dominate starting today. With northerly flow initially, temperatures will be
near to slightly below average, with nights being much colder than recently due
to more radiational cooling, with many inland locations falling below 10F (-12C) tonight but especially tomorrow night. That
is actually quite seasonable for early February, but we haven’t seen many
nights that cold this winter.
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| Source: TropicalTidbits |
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| Source: TropicalTidbits |
As the high pressure slowly moves east throughout the week,
whatever little cold air left will be modified, and it will turn mild by Friday
as winds turn to southerly. A low pressure will be moving into the Great Lakes and
northern Ontario but weakening, eventually moving into our area by Saturday
with increasing clouds and only light precipitation, all falling as rain due to
the very mild temperatures. Behind this low pressure, cold air gradually
returns from the northwest as the central Canadian ridge breaks down and allows
more colder Arctic air to penetrate into our region. The incredible lack of
deep snow cover anywhere in the northern U.S. and southern Canada will lead to
modification of any cold air masses, so I don’t expect to be particularly cold,
especially at first. A storm could move from the Gulf of Mexico region into our
area around February 12 or 13, and it will probably actually be cold enough for
snow then.
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| Source: TropicalTidbits |
Starting mid-February, there is strong ensemble agreement
on a ridge in western North America and a notable trough near the U.S. East Coast, supported by a +PNA and a -AO. This would lead to a colder, though likely not extremely cold
pattern due to the lack of snow cover, with potential for Nor’easters to develop if juicy storms from the
subtropical jet can position themselves ahead of any shortwaves in the northern,
polar jet stream rotating around the deep U.S. East Coast trough. Ideally, the
trough position would be a little farther west for Nor’easters, or they will
not get going until they are offshore, or they will just be shoved too far
south and east for our region, in which case it will just be relatively dry. But
the mid-February into March period could bring the best chance for our region to
experience widespread snowstorms from Nor’easters. Winter might be saving its
best for last.
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| Source: Climate Prediction Center |
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| Source: TropicalTidbits |
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