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March 2018

Puzzling Snow-To-Water Ratios Between Central Park & LaGuardia During Recent Snowstorm

Oprah meme

 

Although Central Park and LaGuardia are only seven miles apart, their snow: liquid ratios from the recent Dec. 16-17 snowstorm were very different.  Although the weather stations at each location reported similar amounts of snow (10.5" and 10.1", respectively) LGA's was from much less liquid (0.69" vs. CPK's 1.52").  Newark Liberty airport also had much less liquid than CPK but measured 11.4" of snow.  If the one-inch of snow for every 0.10" of liquid ratio applied, Central Park would have had more than 15" of snow, LGA just 7".

 

Chart - snow to liquid ratios dec 1617

This isn't the first time Central Park's snowfall was well below what the liquid content would suggest.  It also occurred during a March snowstorm in 2018 when 8.4" fell on March 21-22.  Central Park's 8:1 ratio (based on 8.4" of snow from 1.05" liquid precipitation) is what you'd expect for a heavy, wet snow while LGA's 15:1 ratio (9.7" of snow from 0.64" liquid) is what you'd expect in Arctic air - yet, the temperature at the airport was mostly 33°-34° during the storm while CPK's was 31°-32° (an average ratio is 10" of snow from an inch of water).

 

And the disparity between the two locations was even greater in the last few hours of the storm (after midnight on 3/22) as Central Park picked up 0.2" of snow from 0.06" of liquid while LGA measured 0.9" of snow from just 0.1" (which would produce a very powdery snow).  That's extreme and more common when the air temperature is in the teens, not one degree above freezing.  Bottom line, LaGuardia's ratio is very puzzling.

 

Chart - snow to liquid ratio
 

 Snow to liquid ratio


February 2018 Pushes Past February 2017 to Become Mildest on Record

Warmest february on record in new-york-city

 

Some weather records for warmest and coldest month have been in place for decades.  For example, the warmest January, March and June have been on top since 1932, 1945 and 1943, respectively.  But this February was an extremely rare instance in which a new record broke the one that was  established just one year earlier (October 1946 also lost its crown 12 months later as did August and November 1895).  With an average temperature of 42.0, February 2018 was 6.7 degrees above average.  This was 0.4 degrees milder than Feb. 2017, and just 0.5 degrees below a typical March. 

 

The highlight of the month was the June-like high of 78° on 2/21.  Not only was it the eleventh time a 70-degree reading occurred in February, it was the warmest reading ever reported in February, besting the previous record (in 1930 and 1985) by three degrees.  (But within 24 hours the temperature fell into the more seasonable upper 30s.)  This was also the second February in a row with a high in the 70s - the only time this has happened.  Additionally, for the first time, three Februarys in a row ('16, '17, '18) had five or more days with highs in the 60s or warmer.

 

78

 

Compared to last February, February 2018 was also much wetter, with more than twice as much precipitation (5.83" vs. 2.48").  At one point during the month there was a stretch of twelve days (Feb. 14-25) in which every day but one had measurable precipitation, one of the greatest concentrations on record.  However, the amount of precipitation was a relatively modest 2.01", which was just a little more than what fell from the rainstorm of Feb. 10-11 (1.79").

 

There were 17 days of measurable precipitation, tying it with February 1884 as the most ever for the month.  However, despite this high frequency the month didn't rank among the ten wettest (nor did Feb. 1884, which had an inch less precipitation than 2018).  However, it still had nearly twice as much precipitation than average (5.83" vs. 3.04") and ranks as thirteenth wettest February (placing it among the top 10% of the years since 1869).  Lastly, this was the wettest February in eight years.

17days There were a few touches of winter during the month, with the coldest day, on 2/3, having a high/low of 31°/16° (coldest day of the month).  In total there were eight days with colder than average mean temperatures (two more than Feb. 2017).  4.4" of snow fell on 2/17 despite the temperature not being 32° or colder while the snow was falling.  This snowfall came at the end of a week that had three days with highs in the low 60s and was followed a few days later by days with highs of 67° and 78°.

 

Old man winter

 

February 1998, which shared the title of mildest February with 1984, and later 2002, until 2012, still has the mildest average low temperature of any February, 0.4 degrees warmer than either February 2018 or 2017.

 

Chart - mildest februarys

From Feb. 11 thru Feb. 28 temperatures were eleven degrees above average.  Last February, during the very same period, temperatures were nine degrees above average.

 

Finally, February's record warmth came just four months after the warmest October on record and one month after New York experienced one of its longest stretches of high temperatures of 32° or colder (fourteen days).  And just three years ago one of the coldest Februarys on record had an average high that was more than two degrees colder than this February's average low (32.1 vs 34.5). 

 

Feb 2018 v 2017

Other recaps of past Februarys:

February 2017

February 2015