Unusual March Cold


2017-03-03-1445UTC-rgb-l.jpg
GOES-East RGB imagery showing a cold front just east of Bermuda with trailing cloudiness spreading over the island on the 3rd March at 14:45UTC. This front was responsible for bringing yesterday’s very cold weather.

On the 3rd of March a cold front pushed across the Western Atlantic and reached Bermuda in the morning. It brought an unremarkable amount of rain (0.67″ at the Bermuda Weather Service) and a sharp wind shift from west-southwest to north-northwest. This northwesterly flow continued through the weekend bringing in continental polar air originating over Northern Ontario and Quebec. This same airmass was responsible for record cold air across the Northeastern United States.

Cold air filtering over the waters of the Western Atlantic resulted in widespread ocean-effect shower activity. These showers began to reach Bermuda on Saturday night and intensified during the day on Sunday afternoon with some of the heavier showers containing small hail. Rain-cooled air in the downdraughts of these showers helped keep and nudge temperatures down through the day. In fact, a new record low was set for the 5th by early-morning and Bermuda stayed below the previous record for much of the afternoon and overnight, bottoming out at 47.7°F. This passes the previous record for the 5th of 52.0°F set in 1978. Meanwhile, near-gale force winds occasionally reaching gale force around those showers helped make it feel even colder.

temperaturegraph
Temperatures 3rd March through the 5th March meteorological days. We see the sharp drop in temperature on the 3rd associated with showers along the cold front, followed by a slow and steady decrease in temperatures on the 4th. Temperature fluctuations dominate on the 5th as widespread showers move in with rain-cooled downdraughts. Temperature data from Bermuda Weather Service.

How unusual was Sunday’s cold weather?

Yesterday’s high temperature only reached 56.1°F, this is the second coldest March high temperature on record (since 1949), only surpassed by 19th March 1967 when the high was 56°F*. This was also the coldest high temperature of any day since 55.4°F on the 15th January 2000.

The average temperature for the day (as the max + min divided by two)** was 51.9F, making it the coldest March day on record since 1949 beating 52°F in 1979 and 1951. This was the lowest average temperature of any day since 25th January 2003 with a mean temperature of 51.6°F. Incidentally, this mean temperature is also lower than the former record low for the day.

The low temperature of 47.7°F was the 7th coldest March temperature on record. It was the coldest March low since 2001 when it hit 45.6°F on the 7th of March, and the coldest day of any month since a low of 47.1°F on 27th February 2006.

Essentially, yesterday was about as cold as it gets in Bermuda in March – and it has only been a few degrees colder a handful of times on any day in the period of record. Bermuda should see a gradual return to near seasonal averages as high pressure builds in from the west and the northerly flow weakens begins to veer, becoming easterly by Wednesday morning.

Follow the Bermuda Weather Service to track the warm-up over the next few days and for the latest official forecast, observations, and warnings.

Table of ranked low temperatures as measured for the meteorological day 0600UTC to 0600UTC at the airport.

1 11-Mar-1951 45.0°F
2 7-Mar-2001 45.6°F
3 10-Mar-1951 46.0°F
12-Mar-1991 46.0°F
4 19-Mar-1979 47.0°F
5 8-Mar-1999 47.1°F
6 9-Mar-1999 47.3°F
6-Mar-2001 47.3°F
7 5-Mar-2017 47.7°F
8 21-Mar-1979 48.0°F
17-Mar-1981 48.0°F
16-Mar-1988 48.0°F
11-Mar-1991 48.0°F
25-Mar-2009 48.0°F
* Observations made prior to 1995 were made to the nearest 1°F, nearest 0.1°F after 1995.
**Daily averaged temperatures are impacted by the above uncertainty. Rounding to the nearest 1°F yields a mean of 52.0°F, tying the record. Additionally, a recent method change results in a daily averaged temperature of 52.2°F for yesterday which is the second coldest March temperature, but isn’t comparable to the majority of the period of record.
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