Huge Temperature Swings to Sock the Northeast Ahead of Early-Week Storm 

Huge Temperature Swings to Sock the Northeast Ahead of Early-Week Storm

By: Bob Henson , 10:01 PM GMT on February 12, 2016 
 

From frigid, near-record lows this weekend to mild, soggy highs on Tuesday, New York and New England are about to experience one of the most dramatic chill-down-to-warm-up sequences in memory. The brief but sharp cold will extend across the eastern U.S., but the most dramatic temperature swings are expected from Washington, D.C., northward. Some locations from Philadelphia to Portland will rocket from temperatures near or below 0°F on Saturday night--plus much lower wind chills--to readings near or above 50°F by Tuesday.

The weather whiplash is being produced by a highly dynamic pattern that’s pushing cold northerly winds across the region this weekend. As we discussed on Wednesday, this is a deep-layered cold intrusion rather than a shallow, frigid surface air mass. This means that the cold may not set dramatic records at low-elevation towns and cities, but at higher elevations, the chill will be truly exceptional (see below). Because there won’t be a sharp inversion locking in the surface cold air, it will be much easier to scour out than usual. That’s exactly what will happen from Sunday through Tuesday as a strong surface low spins up over the Carolinas and moves northward near the coast, perhaps just inland or just offshore. To the east of the storm, winds will be howling at all levels from the south, pushing in mild maritime air to displace the weekend chill. The orientation of this flow may actually bring milder temperatures to New England than to the mid-Atlantic, accentuating the whiplash effect further north.

The exact track of this storm--impossible to pin down at this point--will dictate how a potpourri of heavy rain, sleet, freezing rain, and snow evolves across the region. The ECMWF model has consistently taken the surface low inland toward central New York, whereas the GFS model has trended further east, but with more run-to-run variation.


Figure 1. Surface air temperatures in °F predicted by the 12Z Friday run of the GFS model for 7:00 am ET on Sunday, February 14, 2016. Image credit: Levi Cowan, tropicaltidbits.com.


Hang on to your hats--and your coats!
As of Friday afternoon, the WU forecasts for major East Coast cities (below) suggest that a few daily record lows might be set on Valentine’s Day (Sunday, Feb. 14). Amazingly, if Boston manages to set a record low on Sunday morning, it will be their first daily record low for the entire month of February in almost 50 years, since -3°F on Feb. 13, 1967 (thanks to Eric Fisher, WBZ, for this tidbit). The potential temperature swings from Sunday to Tuesday are more akin to those felt in dry Western climates!

Predicted low for Sun., Feb. 14, and predicted high for Tues., Feb. 16 (asterisk indicates daily record low)
Portland, ME: -4°F to 43°F (spread of 47°F)
*Boston, MA: -4°F to 50°F (spread of 54°F)
Providence, RI: -6°F to 50°F (spread of 56°F)
Burlington, VT: -4°F, 37°F (spread of 41°F)
*Albany, NY: -11°F to 39°F (spread of 50°F)
Buffalo, NY: -8°F to 36°F (spread of 44°F)
*New York, NY (Central Park): 0°F to 50°F (spread of 50°F)
*Philadelphia, PA: 0°F to 47°F (spread of 47°F)
Washington, DC (National): 10°F to 47°F (spread of 37°F)



Figure 2. As shown by this Wundermap, temperatures at the 850-mb level (about a mile above ground) projected by the 12Z Friday run of the GFS model for Saturday night (top) will drop below -30°F in places. This will be close to the lowest ever observed by radiosonde across parts of the Northeast. The yellow region over the Adirondacks corresponds to predicted values colder than -29°F about a mile above sea level at 10:00 pm EST Saturday, Feb. 13, 2016. Less than three days later (bottom), at 7:00 pm EST Tuesday, Feb. 16, readings at this altitude may soar above 46°F over southern New England.


Radiosondes may provide our most impressive benchmark of this weekend’s cold event. In the soundings to be launched at 0Z Sunday (7:00 pm Saturday), the temperatures at 850 mb (about a mile above sea level) may challenge February record lows at New York and Boston, in data going back to 1948. Buffalo has a shot at its monthly 850-mb record low on Saturday morning, and on Saturday night, Albany could break its all-time coldest radiosonde-measured 850-mb temperature (current record -31.8°C, interpolated from data on Feb. 8, 1963; thanks to Patrick Marsh, NOAA Storm Prediction Center).

Weather pick of the weekend: Mt. Washington, New Hampshire
There aren’t many weather stations at high altitude over the Northeast, but those that exist will get a wintry hammering this weekend. The most venerable of these is atop Mount Washington, NH (elevation 6289 feet), where the Mount Washington Observatory was established in 1932. The MWO’s Friday afternoon forecast for higher summits in the region is a jaw-dropper: “Temperatures will fall steadily into Saturday night where they will bottom out in the mid 30’s below zero....The coldest air and the highest winds will likely occur at the same time so wind chills late Saturday into Saturday night will be approaching 90 below zero. These are extremely dangerous conditions to be exposed to for any length of time.” Winds are expected to gust as high as 95 mph.

The MWO station dipped to -35°F three times in February 2015. The last time a colder temperature was recorded was -37°F on February 6 and March 6 of 2007, according to Mike Carmon, co-director of summit operations. The most recent temperature below -40°F was -45°F on January 14 and 15, 2004. “We do not keep records of wind chills at the summit, being that they are constantly-fluctuating and calculated values,” Carmon told me in an email. “Off the top of my head, though, I can say the last time we hit wind chills approaching -90F was almost exactly one year ago during the President’s Day polar outbreak of 2015.”

The coldest temperature ever observed at the summit actually predates MWO. A U.S. Signal Service station that operated sporadically from the 1870s to 1890s reported a low of -50°F on Jan. 22, 1885, according to the Northeast Regional Climate Center. This reading is not yet reflected in NOAA’s digital data files but exists in NOAA archives.


Figure 3. The Mount Washington Observatory, encased in rime ice on April 7, 2004. Image credit: Talinus/Wikimedia Commons.

Other all-time records at higher-altitude stations across the Northeast also date back many decades. They include:

Pinkham Notch, NH (2010 ft): -32°F on 2/16/1943
Mt Mansfield, VT (3950 ft): -39°F on 1/9/1968 & 1/15/1965 & 1/15/1957
Lake Placid, NY (1940 ft): -39°F on 12/30/1917
Whiteface Mtn., NY (4865 ft): -36°F on 1/25/1945 (period of record is 9/1937-8/1946)
North Lake, NY (1831 ft): -47°F on 2/9/1934 (period of record is 9/1896-5/1948)
Slide Mtn., NY (2650 ft): -23°F on 1/18/1982 (period of record is 12/1961-10/2012)
(Thanks to Jessica Spacio at the Northeast Regional Climate Center for these data.)

Meteorologist Anton Seimon (Appalachian State University/University of Maine) got a taste of high-altitude Northeast cold on a ski trip in mid-January 1994 to Lake Colden, NY (elevation 2762 feet). “On that Saturday night [Jan. 22], our mercury thermometer spent several hours parked at -45°F (-42.7°C) while winds in the strongly channeled lake corridor gusted to about 25 knots with blowing snow.” Seimon said in an email. “We did measure even colder temperatures in the central Adirondacks on other excursions during that winter, but those were under calm, radiative cooling conditions. In terms of pure cold and wind chill, the 1994 Lake Colden night remains the superlative event in my recollection.”

We’ll be back with another post by Tuesday morning at the latest. Have a great President’s Day weekend, and stay warm!

Bob Henson