Plain-language summary:
The prolonged cloudy, cool, and unsettled weather pattern
from earlier in the week is reversing to a prolonged warmer, dry, and mostly
sunny weather pattern for the next 7 days, aside from a few possible showers in
the southern Adirondacks Sunday night and some possible showers Friday and Friday
night, especially in northern areas. Temperatures will be unusually consistent
from day to day for spring, with there being more temperature variation between
day and night instead. It could turn cooler and more unsettled for several days
after next weekend, but heavy rain is unlikely. While uncertain, it could warm
back up afterward.
Meteorological discussion:
What a difference a week makes. We are entering an unusually
long period of not only dry, mostly sunny weather, but also rather mild to warm
but not hot temperatures. Like the prolonged unsettled pattern we just came out
of, this new dry pattern is due to a slow-moving, blocked pattern. This time,
the blocked pattern consists of an upper-level ridge over central Canada and an
upper-level trough over Atlantic Canada, with dry northwesterly flow in between
in our area. Despite the northwesterly flow, the lack of any cold air mass to
tap into and the record heat in western and central Canada means that this flow
will actually be rather warm, but not hot. The northwesterly flow will also be
very dry, cutting off the region from Gulf of Mexico moisture. Not much rain is
expected for the next 7 days and possibly longer. A few showers will occur in southeastern
Ontario, southern Adirondacks, and southern Vermont from a weakening system
diving to the southwest tonight, but the rest of the area will just see
increased clouds. A system will sneak in a slightly cooler air mass on Monday,
but most of the cold air mass will remain to the northeast and the May sun
angle will quickly modify any cool air mass. Another system, this time passing
to the north, could bring showers Friday and Friday night, especially in
northern areas, before ushering in a slightly cooler air mass again. It will be
rather warm ahead of it on Wednesday and Thursday. While spring usually is
characterized by frequent ups and downs in temperatures, temperatures will be
consistently spring-like for the next 7 days or so, with high and low
temperatures varying by no more than 18F (10C). There will be more temperature
variation within a day though, due to the dry air and mostly clear skies
leading to a large diurnal temperature range.
By next weekend, an unusually strong ridge will build over
western Canada. It will likely still be warm in our region at that time, but
the ridge will eventually have the downstream effect of building a trough in
eastern Canada. This will likely pull down colder air masses from iced-over
Hudson Bay and lead to more low pressure and showery and perhaps breezy
weather. Even so, the prevailing westerly or northwesterly flow is unfavorable
for pulling in rich Gulf of Mexico moisture to produce heavy rain. There are
some early indications that there could be an impressively cold air mass for
mid-May. It might be too cloudy and/or windy for frosts or freezes in the
broader valleys, but that is uncertain for now, and the normally colder
locations have a decent chance of seeing frosts or freezes, with even higher
elevation snow showers. The western ridge could be transient and weaken later the following week, which would kick the cold air
out of our region, but this is too far out to have much confidence in.
No comments:
Post a Comment