Historic Warmth, Wednesday, February 21, 2018

Record breaking warmth generally does not warrant an analysis in a monthly summary. However, this latest episode of extraordinary warmth is again noteworthy as the cold season occurrences of record heat to date have been increasing which makes it important to continue documenting.

The 73° high temperature recorded at Albany on February 21, 2018 fell only a degree short of equaling the all time February record high temperature at Albany as well as the highest temperature on record for all of meteorological winter, the months of December, January, and February. That record is 74° which was only set a year ago on February 24, 2017, and previously set on December 24, 2015. The 73 degree high did, however, easily break the daily record high for February 21 of 65° which was set in 1981.

Prior to February 2017 there were no days in the month of February at Albany with a high temperature of 70°. So, to have two back to back February's which included a day where the temperature reached at least 70° is astounding, and certainly not normal. What's also so remarkable is the fact that what was once a roughly fifty to sixty year occurrence, based on the 144 years of temperature records at Albany to date, of a temperature of 70° or higher occurring in the winter, has recently become almost common. Of the seven days on record at Albany with a high of 70° or greater, five of them have occurred since 2007 with four of those five occurring in only the last two years, to date.

Unlike the February heat event in 2017, which was extreme, encompassing a three consecutive day string of uninterrupted record warmth with the temperature reaching 69° on the 23rd, 74° on the 24th and 70° on the 25th, the heat on February 21, 2018 was brief in duration. Temperatures in this event climbed to 60° or higher for five hours from 11am through 3pm, with temperatures at or above 70° for three of those hours from 1pm through 3pm. The high temperature of 73° occurred at 2:44pm with the passage of a cold front shortly after that dropping temperatures into the upper 50s by 4pm and into the 40s through the evening.

To date, the list of very rare 70°+ days at Albany in meteorological winter grew from six to seven in February 2018

February 24 2017 74°
February 21 2018 73°
December 24 2015 72°
January 6 2007 71°
December 29 1984 71°
January 13 1932 71°
February 25 2017 70°

Records @ Albany for the February 21, 2018

February 21: Daily high temperature: 73° at 2:44pm - Sets a new record high for the date
, previous 65°/1981
February 21: Record high mean temperature: 55.0°,
previous 48.0°/1981
February 21: 2nd Highest February temperature on record to date
, previous 70° February 25, 2017
February 21: 2nd Highest Meteorological Winter Temperature on record to date, previous 72° December 24, 2015

Peak temperatures at 850 mb at Albany climbed to a general range of +10° to +12° C on average from the 20th through the 21st, with much deeper atmospheric mixing on the 21st accounting for surface temperatures climbing ten degrees higher than on the 20th. These 850mb temperatures compare to +8° C to +10° C during the three day February 2017 heat event and +13° to +15° C in the December 24, 2015, event. Atmospheric mixing was deeper in both this event and especially the February 2017 event compared to that in the December 24, 2015 which is why surface temperatures climbed a little higher than in December 2015, despite the higher 850 mb temperatures.

The increased frequency of winter high temperature extremes is a symptom of the warming climate, where the antecedent atmospheric conditions are now more supportive of high temperature extremes in weather patterns that favor warmer than average conditions. Increased greenhouse gases in the atmosphere have now stacked the deck in favor of hot spikes like what occurred in this event, to occur with increasing frequency in the future, while cold extremes become less cold and less frequent over time.

Set Up
The heat set-up for this event was similar to the warm events on both December 24, 2015 and January 6, 2007, in that pre-existing surface conditions then and with this situation were initially mild with no snow on the ground. Temperatures on the 20th climbed into the low 60s for highs with temperatures ranging from the mid to upper 50s through the night and pre-dawn hours of the 21st. Further, an advancing cold front, which was present in both the December 2015 and January 2007 cases, was also present in this case with some compressional warming taking place in advance of the frontal passage helping to boost surface temperatures into the low and mid 70s, with a 77° high temperature on the 1pm observation at Bennington, VT, a new high temperature record for February for the entire state of Vermont. The surface wind however, in this case remained southerly vs. southwesterly, up the Hudson valley. A southwest wind is a downslope wind which had it become pronounced would have further aided in compressional warming of the air as that air flowed down off the Catskills into the Hudson valley. The lack of a strong downslope flow in this case meant the full potential of warming was not realized as it was in the December 2015 and January 2007 cases when the downslope flow was much more pronounced. Despite the surface flow not being optimal, the high temperature was still higher in this event, a testiment to just how warm the atmosphere was through a deep layer. The cold front also moved through earlier in the day in this event, roughly between 2 and 3pm in the Capital Region, with cloud cover coming in, in advance, which also limited a potential for a few extra degrees of warming. Had the front been a little slower, surface temperatures would have climbed several degrees higher based on how warm the mid and upper levels of the atmosphere were through the morning with record geopotential heights at the 500 mb level of 583 dm (decimeters) at 7am on the 21st at Albany with the ridge itself along the Atlantic seaboard peaking out at an astounding for winter 595 dm.

In fact the upper level ridge appears was the strongest on record for any January or February, a feature created by a tremendous amount of warm air throughout the atmospheric column in a pattern that was created by a sharp kink which developed at the jet stream. Across the western U.S. the jet dipped far to the south allowing for a record cold air mass to invade the west with the ridge being forced over the east. A sudden stratospheric warming a week preceding this event caused the stratospheric polar vortex to split which created the unstable jet stream pattern leading to the large amplitude trough across the west and strong ridge across the east, which is not particularly uncommon. But, the magnitude of the heat extreme was uncommon, and can be attributed to an atmosphere that is now in general warmer than it has been at any time in human history. This tips the scale in favor of extreme warmth in cases when a weather pattern sets up to support warmer than average conditions.

The figure below is the analysis of the upper level high pressure ridge (500 mb level - roughly 4 miles up and the mid point of the atmosphere's density) at 12z (7am local time) on Wednesday, February 21, 2018 as well as the height anomaly, in other words, how much above average the heights of the 500 mb pressure surface were at the time - graphic courtesy of tropicaltidbits.com. The colors show the departure in decameters from the average height of the 500 mb pressure surface at this time of the year and are described as mind blowingly high by the greater atmospheric science community.

12Z (7am local time) 500mb Height and Anomaly Analysis, Feb 21, 2018 

The heat ridge contributed to 75 new record high temperatures being set, many all time records for the month of February, from Maine to North Carolina. In eight states, including Pennsylvania, New York, Vermont, New Hampshire, Maine, Massachusetts and Ohio, the all time highest temperature for the month of February was either tied or set, to date.

State - City Record Previous Record
Pennsylvania - Capital City 83° 83° (Tie)
New York - La Guardia 79° 78°
Vermont - Bennington 77° 68°
New Hampshire - Manchester 77° 72°
Maine - Wells 77° 69°
New Jersey - Teterboro 83° 80°
Massachusetts - Fitchburg 80° 73°
Ohio - Cincinnati Airport 80° 80° (Tie)


1pm Northeast Regional Temperature Observations on Wednesday, February 21, 2018

1pm Northeast Regional Temperature Observations, Wednesday February 21, 2018

1pm Northeast Local Temperature Observations on Wednesday, February 21, 2018

1pm Local Temperature Observations, Wednesday, February 21, 2018 

2pm Northeast Regional Temperature Observations on Wednesday, February 21, 2018

2pm Northeast Temperature Observations, Wednesday, February 21, 2018 
3pm Northeast Local Temperature Observations on Wednesday, February 21, 2018

3pm Northeast Temperature Observations, Wednesday, February 21, 2018

4pm Northeast Local Temperature Observations on Wednesday, February 21, 2018

4pm Northeast Temperature Observations, Wednesday, February 21, 2018 

Temperature, Dewpoint, Wind Plot For Albany, Wednesday February 21, 2018
Normal High = 36°
Normal Low = 19°

TIME
TEMPERATURE
DEWPOINT
WIND DIR/SPEED
12am
57
50
South 6 mph
1am
57
50
South 8 mph
2am
57
51
South 12 mph
3am
55
50
South 8 mph
4am
57
51
South 10 mph
5am
56
52
South 9 mph
6am
56
52
South 13 mph
7am
56
52
South 9 mph
8am
56
52
South 15 G 20 mph
9am
57
53
South 13 mph
10am
59
54
South 31, G 21 mph
11am
63
54
South 16 mph
12pm
67
54
South 17, G 23 mph
1pm
70
54
South 15, G 23 mph
2pm
70
54
South 10 mph
3pm
70
53
NW 28, G 36 mph
4pm
59
49
West 22, G 31 mph
5pm
54
46
West 21 mph
6pm
52
44
West 16 mph
7pm
49
40
NW 14 mph
8pm
43
34
West 18, G 30 mph
9pm
42
34
NW 10, G 23 mph
10pm
41
33
NW 9 mph
11pm
40
33
NW 8 mph