COMMENTARY
Reminder for model watchers: Do NOT get hung up on anything you see beyond 3-days in advance. A perfect example, the day 5 forecast between the 00z run for the Canadian, US, and European models all differ enough that a forecast made verbatim from each of them would look like a forecast for 3 different low pressure systems impacting the region. And this applies to everybody regarding their weather app forecasts beyond a couple days. Some of this guidance is already 24 hours off on day-of-impact with things under a week away, and when they have the right day other things are wrong. Do yourself a favor and listen to meteorological discussions that have taken into account glaring model issues in this weather pattern…
DAYS 1-5 (DECEMBER 4-8)
A chilly weekend is in store for us but nothing outrageously cold. The remains of a dissipating clipper low will be moving in today and you’ll notice it in the form of clouds. These clouds have the potential to release a few snowflakes but the air is dry enough that they may never reach ground where they fall. A sliver of high pressure brings fair weather for Sunday. Timing worked out for a generally nice weekend, but we’re still in an active pattern and there will be two low pressure systems to contend with before this 5-day period ends. The first one will be a strong low that I’m confident will be heading east northeastward from the Great Lakes across southeastern Canada on Monday. Its warm front will come through during the early to mid morning when we have our best chance of rain. After that, it’s time for a warm wind from the southwest behind the warm front and ahead of an approaching strong cold front. The wind will be quite gusty so if you have outdoor decorations vulnerable to wind you’ll want to secure them before this weekend is over, if you have not done so already. While the region is in the warm sector, the atmosphere will be unstable enough so that we may see a couple of isolated showers and even thunderstorms Monday afternoon favoring the South Coast region. It would be these that would have the best potential to produce damaging wind gusts, even show some rotation. The timing of Monday’s cold front appears to be evening, after sunset, from west to east, and it should produce a band of rain showers, a few of which may be heavy and contain small hail, with even the possibility of a thunderstorm. Gusty, shifting winds will occur with the passage of this front. Following the frontal passage will come a sharp temperature drop and Tuesday, while dry, is going to be up to 30 degrees colder than what we have Monday. Classic La Nina temperature roller coaster pattern. This cold air sets up the potential for frozen precipitation for at least portions of the region for the next low pressure threat, which is Wednesday. Keeping in mind this is day 5, the only thing I can say at this point is this low track will be much further south than Monday’s, passing over or just south of New England, with highest probability of snow/sleet being over interior locations and a higher chance of mix/rain closer to the coast. Fine-tuning of both the low’s track and resultant precipitation type and intensity/accumulation will take place as this event gets closer, and after we improve the focus a little bit for tomorrow’s blog post, it will be Monday’s discussion will contain much more detail on the system. I will tell you that I’ve already seen snow amounts mentioned somewhere in media for this system. I will not say where, but I will say that I highly disagree with such a practice for any system that far in advance and most especially for something occurring in the situation I discussed in my commentary…
TODAY: Sun/cloud mix. Highs 36-43. Wind W up to 10 MPH.
TONIGHT: Variably cloudy. Slight chance of a very light snow shower. Lows 21-28. Wind NW up to 10 MPH.
SUNDAY: Mostly sunny. Highs 37-44. Wind N up to 10 MPH.
SUNDAY NIGHT: Increasing clouds. Chance of light rain overnight. Lows 30-37 evening, rising into the 40s overnight. Wind variable under 10 MPH evening, S 5-15 MPH overnight.
MONDAY: Cloudy with a chance of rain early, then mostly cloudy to partly sunny. Slight chance of an isolated rain shower or thunderstorm near the South Coast in the afternoon. Highs 61-68. Wind SW 10-20 MPH, gusts 30-40 MPH and slight chance of gusts above 40 MPH.
MONDAY NIGHT: Mostly cloudy evening with a passing rain shower and potential downpour with possible thunder and/or small hail west to east. Partly cloudy overnight. Lows 33-40. Wind SW 10-20 MPH gusting 30-40 MPH and potentially higher in any convective activity, shifting to NW from west to east.
TUESDAY: Partly cloudy. Temperatures steady 33-40. Wind NW 10-20 MPH with higher gusts, diminishing later in the day.
TUESDAY NIGHT: Increasing clouds. Lows 23-30. Wind variable up to 10 MPH.
WEDNESDAY: Cloudy. Rain and snow likely. Highs 33-40. Wind NE 5-15 MPH.
DAYS 6-10 (DECEMBER 9-13)
The active weather pattern continues but model guidance is not reliable. Best guess is that a weak low pressure area brings a minor precipitation threat December 10 and a stronger one tracks north of the region later in the period with a milder surge and a rain chance of some kind.
DAYS 11-15 (DECEMBER 14-18)
Mild and active pattern to start with a chance or two of unsettled weather from passing systems through the middle of this period and then the chances of a return to some cold for later in the period.