ITHACA, N.Y. — In winter, any week without subzero temperatures or a raging snowstorm is a little blessing in itself. In that sense, this week should be a blessing, as high pressure prevails during the first half of the week, with some weak disturbances in the second half that may bring a few rain or snow showers, but it’s highly unlike to pose any major issues.
With the data for December 2020 finalized, and all of the 2020 data finalized for that matter, let’s have a look at the month and year of 2020 from a meteorological perspective.
First, let’s look at the month in review. According to the Northeast Regional Climate Center based out of Bradfield Hall on Cornell’s Campus, December was a tad on the warm side with a relatively mild temperature average of 30.5°F, which doesn’t sound like much but it’s 1.8°F above normal. That’s good enough for 39th place out of Ithaca’s 120 years of relatively complete December temperature records. So above average, but nothing especially remarkable. Across the Northeast, the story was much of the same, with only two of the 35 first-order climate sites reporting top ten warm Decembers – Caribou, Maine (4th warmest) and Burlington, Vermont (9th warmest). All but one station (Charleston, West Virginia) were above normal for the month.
On the precipitation side, as is often the case with a stat so dependent on storm tracks, it was feast or famine. Ithaca was, in that sense, more towards feast, with a wetter and snowier month than usual thanks to that storm the week before Christmas. The Game Farm road site in Dryden recorded 3.79″ of liquid-equivalent precipitation and 18.1″ of snow, above the normals of 2.40″ and 12.6″ of snow. Binghamton, for all the snow it received, still only had its third-wettest December on record. Washington-Dulles Airport, Providence, and Worcester, MA also had top-ten wettest Decembers. Five stations were on the dry side, mostly thanks to a southerly storm track than usual – that includes Rochester, Syracuse and Burlington, which had half of its normal precipitation.
Looking at the data for all of 2020, that too, was on the milder side – the average temperature for the year was 48.1°F, 1.5°F above the normal of 46.6°F. Compared to the cool year that was 2019, whereas that year was the 24th coolest in the 118 years of complete records, 2020 was the 22nd warmest. January 2020 was the warmest month relative to average (+5.7°F), and April the coolest (-4.1°F) – the cooler half of the year is where the records tend to be built, due to a stronger gradient between the tropics (which stay warm throughout the year) and the Arctic, leading to more variable conditions. A 3.0°F temperature anomaly in June is very unusual. A 3.0°F anomaly in January isn’t uncommon.
Compared to the rest of the Northeast, though, Ithaca was a relatively cool spot. Every station was above average. 32 of the 35 first-order climate stations had a top-ten year for warmest year on record. Six of those stations set their all-time record highs in annual temperature – Scranton, Harrisburg, Atlantic City, New York City/Central Park, Providence, and Portland, Maine.
On the precipitation side, we were fairly close to normal, just a hair on the dry side – 36.81″ of liquid and liquid-equivalent precipitation, vs. a climatological normal of 37.30″. In fact, seven months were above average with February being the wettest, but the bone-dry June and September we had put Ithaca on the dry side for the year. Most of the Northeast was close to normal, either a little above or below normal, with some drier spots in the Adirondacks and New England, and wetter locales south and west of Philadelphia. The most anomalous was Atlantic City, with its fifth-wettest year on record.
In conclusion, 2020 was a mild year with near-normal precipitation. A shame that everything else that happened in 2020 put a damper on it. Coming back to the present, the first ten day of the month have been a lot like 2020 overall, and not just the chaos and calamity in the news. The month has started off on the warm side with near-normal precipitation. Looking into the week ahead, that relative mildness should continue, and a few chances for light precipitation may keep us near-normal as we continue forward through the month.
Your Weekly Weather
It has been a fairly quiet Sunday as a ridge of high pressure sits over the Midwest and extends into the Mid-Atlantic and Northeast. A weak shortwave )pulse of instability) is expected to pass over the northern edge of the ridge overnight and tomorrow morning, and there’s a possibility a few stray flurries may make it as far south as Ithaca (don’t expect more than a dusting), along with a fair amount of cloud cover, but otherwise the weather should remain tranquil. The fair skies present at sunset will steadily cloud over and be mostly cloudy to overcast by sunrise. With that building cloud cover providing some insulation, low temperatures this Sunday night will be in the mid 20s in the urban core and long the lakeshore, and low 20s in the outlying towns and higher elevations.
For Monday, the shortwave should shift eastward fairly quickly, so my noon the clouds will start to clear out, allowing for partly cloudy skies by sunset. With a light south wind as the high pressure system shifts eastward, temperatures will make into the mid and upper 30s. Monday night will be partly cloudy and dry, with lows in the mid 20s.
Tuesday will see the winds shift more southwesterly as the high reorients itself over the Atlantic Ocean. A new shortwave will pass to the north, this one even weaker than Monday’s and lacking moisture, so the only expectation is some additional cloud cover. The southwest wind will allow temperatures to climb a few degrees warmer, with highs near 40°F with partly to mostly cloudy skies. Tuesday night will be quiet, with mostly cloudy skies and lows in the upper 20s.
Wednesday sees the new high pressure system develop over the Western Gulf of Mexico, which reorients the ridge but should keep a west-southwesterly flow into the Southern Tier. Plan for mostly cloudy skies with highs in the low 40s. Wednesday night will see a continued influence of that ridge, with quiet, mostly cloudy conditions and relatively mild lows in the upper 20s (recall our average low this time of the year is in the mid teens).
Thursday will see another shortwave cut across Northern New York on a southeastward trajectory, and this will inject some fresh cloud cover as well as a few rain or snow showers overnight. During the day, southwest winds will continue, with highs in the mid 40s with mostly cloudy skies. Thursday night will see a few rain or snow showers at the shortwave’s closest passage to Tompkins County after midnight, but only light accumulations are expected. Lows will be in the mid 30s.
Friday and Saturday will be interesting as a large and rather potent low pressure storm system skirts across the Upper Midwest and Great Lakes before crossing Canada, well to our north. Although well away from its most significant impacts, it will provide for warmer air ahead of the system (counterclockwise flow) Friday, and cooler air Saturday, along with light rain and snow showers. Friday will be mostly cloudy to overcast, with scattered rain showers and highs in the low to mid 40s. These should change over to snow showers late evening Friday, though no significant accumulations are currently expected. Skies will be cloudy with lows in the upper 20s.
I should note that some of the ensemble model runs do suggest a secondary low forming to the south of the primary low along its frontal boundary, and if that happens the risks for a high-impact event grow. At this time, it appears to be the less likely outcome, and should an update be needed, a special weather update will be posted later in the week.
The low should cross our longitude if well to the north around sunrise Saturday, which will allow for cooler air to come in on its backside. Expect a chance of snow or rain showers early, with mostly cloudy and drier conditions by afternoon and highs in the mid 30s. Saturday night will see a few lingering snow showers with lows in the mid 20s, and Sunday is looking to be sunnier, with partly cloudy skies and highs in the mid 30s.
Looking into the second half of the month, the large scale pattern seems to have a ridge setup that would convey areas of low pressure from the Deep South and into the Northeast, a pattern that would result in warmer and wetter than normal conditions. With that noted, the broad setup doesn’t indicate any extreme conditions expected for the next couple of weeks, with temperatures a few degrees above normal and condition a little wetter than usual – i.e. mild and near normal precipitation, so 2020’s meteorological behavior continues. However, just as weather changes, let’s hope the less savory aspects of 2020 go away as quickly as possible.