The Great Southeaster – November 25, 1950

Storm surge in Southport / Courtesy: Pequot Library Association

Connecticut meteorologists love talking about nor’easters but do you know about the state’s biggest southeaster? The “Great Appalachian Storm” of November 25, 1950 was one of Connecticut’s most violent wind storms on record. In some towns the wind speeds in 1950 were only exceeded by the great hurricane of 1938!

The storm was only of modest strength in terms of central pressure – 980ish mb. But what made the winds vicious was the 1050ish mb high near Maine. The freakishly strong pressure gradient produced violent southeasterly and easterly winds across New England. Here are some of the wind gusts recorded in Connecticut on November 25, 1950.

  • Bridgeport – 88 m.p.h.
  • New Haven – 77 m.p.h.
  • Hartford – 100 m.p.h.

The 70 m.p.h. 1-minute sustained wind in Hartford remains the strongest wind recorded for the official Hartford records since observations began in 1904. The second highest value is 64 m.p.h. recorded during the October 3, 1979 tornado. In Bridgeport the sustained wind of 62 m.p.h. is one of the highest on record (since 1948) with the highest occurring during Gloria in 1985 at 74 m.p.h. sustained and two other higher wind speeds during the winters of 1964 and 1969. Note on record: 2-minute sustained winds replaced 1-minute sustained winds in 1995.

Courtesy: PSU/Richard Grumm

For a non-tropical storm there’s no question in my mind that the 1950 southeaster was the most violent windstorm we’ve seen. The standardized anomalies from Richard Grumm at the NWS in State College shows a wide area of +4 standard deviation 850mb winds. That’s quite a low level jet! The winds reached 160 m.p.h. on Mount Washington in the core of that LLJ.

Looking at the reports from that day here in Connecticut temperatures in the warm sector came close to 60º with highs in the upper 50s in Hartford, Bridgeport, and New Haven. The unseasonably warm weather, when coupled with a a ripping low level jet, lead to enough turbulent mixing to mix down destructive winds – in some cases to 100 m.p.h.!

Here are some of the comments from the official weather bureau reports.

  • Hartford – “Of paramount interest in this month’s weather is the occurrence of “The Great Wind Storm of November 25, 1950″. Considering its great extent, extreme weather of various types, and its unusual meteorological character, this storm will be long remembered. At Hartford, E’ly winds averaged the amazing speed of 38 m.p.h. for the entire day of the 25th, and attained gust speeds of at least 100 m.p.h. on at least 3 occasions between 4:30 and 7:30 p.m..”
  • Bridgeport -” Storm of Nov. 25th worst since 1938. Station inundated with 4 to 5 feet of water.”
  • New Haven – “Severe southeast storm on 25th. Extensive wind and water damage to shore fronts. Many trees, wires, antennae down, roofs damaged. Max for 5 minutes: 50 SE at 1:55 PM (17 Hrs.), probably exceeded 8:00-9:00 PM. Fastest single mile: 57 SE at 1:56 PM (17 Hrs.), possible exceeded  8:00-9:00 PM. Gusts: 55 MPH at 1:35 PM; 66 MPH at 4:20 PM; 66 MPH at 7:40 PM; 77 MPH 5 second gust at 4:45 PM… 5 min. max record; fastest mile exceded in Sept. 1903.”

12 UTC Surface Analysis / Courtesy: MWR/NOAA

The strong winds produced widespread tree and power line damage across the state. The winds tore a roof off a dormitory at UConn and ripped shingles off roofs across the state. Several shoreline homes lost their roofs according to a Hartford Courant article from shortly after the storm.

The storm surge flooding was extensive on the coast. In New London the tide reached an impressive 7.58ft MLLW. The only storms higher in the last 100 years are the 1938 hurricane, hurricane Carol, and hurricane Sandy. In Stamford at the Hurricane Barrier the tide reached 9.5ft NGVD which was similar to Irene’s tide level.

Laguardia Airport on 11/25/1950       Courtesy: NYC OEM

Much like Sandy, the storm surge flooded large portions of New York City including the lower east side and Laguardia Airport. Sandy’s surge, however, was much more powerful in the parts of the City, like Staten Island and the Rockaways, with Atlantic exposure.

On the Connecticut shoreline houses, cottages, railroad tracks, and beaches were swept away. Newspaper accounts indicate that the sand was several feet deep on coastal roads and was removed by snow plows. Many people had to be rescued from their homes after refusing to heed evacuation orders.

The storm resulted from an exceptionally deep dip in the jet stream and monstrous closed low that formed over the Appalachians in a trough the went negatively tilted. The easiest way to visualize this is to look at the 500mb height anomalies associated with the low. Much like Sandy, there was a large “block” downstream. In the 11/25/1950 case there was a 350+ meter positive height anomaly over eastern Quebec. The upper level low itself over the central Appalachians was an exceptionally impressive 450+ meter negative height anomaly.

This type of unusually deep system lead to unusually cold weather and extreme snowfall in the Appalachians and the Ohio River valley. The storm is one of the worst blizzards in parts of the country. Steubenville, Ohio recorded 44 inches of snow while the synoptic desert of Pittsburgh dug out from 30.5 inches of snow!

In the southeast U.S. the backside of the storm delivered a bitterly cold air mass. The mercury dropped to -3º in Atlanta, GA. Many observing sites saw their coldest November temperatures on record. 850mb temperatures reached an INCREDIBLE -20ºC over northern Georgia at 12z 11/25/1950.

Courtesy: PSU/Richard Grumm

Not very often do you see a -6 sigma 850mb temperature! The exceptional baroclinicity and phasing resulted in what amounted to one of the most impressive east coast storms of the 20th century.

PSD 20th Century Reanalysis

While we frequently refer to the March 1993 storm as the “storm of the century” the November 1950 storm gives ’93 a run for its money. For east coast storms we really had 2 storms of the 20th century.


Historic Flooding Underway in Central and Eastern Pennsylvania

“As bad as Agnes”

For people living in Pennsylvania those 4 words are about as bad as it gets for a weather-related disaster. The headwaters of the Susquehanna River through central New York and northeastern Pennsylvania have seen an absolute deluge of rain thanks for the remnants of Lee.

On Wednesday Binghamton, NY picked up 7.49″ of rain which shattered the old calendar day record of 4.24″. So far in 2011 Binghamton has seen 49.86″ of rain which is now their wettest year on record and it’s only September!

Susquehanna River Watershed

The wet antecedent conditions followed by record rainfall this week is pushing some rivers in Pennsylvania and New York to record shattering levels. The Susquehanna River in Wilkes-Barre and other cities is expected to come within inches (literally, the forecast is 4″ shy of the record) of the 1972 floods from the remnants of Tropical Storm Agnes.

Here is the observed and forecast hydrograph for the Susquehanna River in Wilkes-Barre. The record crest is from Agnes in 1972 at 41.0 ft and the current forecast is 40.7 ft.

Levee protection for Wilkes-Barre is for a river crest of 41.0ft which is way too close for comfort.The levees were constructed in Wilkes-Barre following the devastating floods in Agnes to the river level following Agnes. Not sure anyone thought we’d see those levels again just 39 years later.

Tributaries of the Susquehanna have already seen record flooding with entire homes isolated and submerged. Other locations upstream and downstream from Wilkes-Barre will see similar flooding. Areas outside of levee protection are submerged.

Having gone to Penn State and having been to northeast Pennsylvania many times my thoughts go out to my friends in Pennsylvania. It is absolutely incredible how many “100 year floods” we’ve seen in the northeast over the last several years. The 2011 flood of the mighty Susquehanna will be yet another one in this incredible streak of extremes. It’s quite possibly with a changing climate “100 year floods” aren’t as rare as they once were.

Record Shattering Flooding in North Dakota

You may have heard about the record flooding on the Souris River in North Dakota on the news the last couple of days. An exceptional amount of rain has fallen in the northern Plains and has lead to a record shattering flood on this relatively small North Dakota River.

Souris River Hydrograph

The previous flood of record was in 1881 with a crest of 1558.0 feet. This weekend the Souris crested at 1561.7 feet. At this height some of the levees were topped by the river and the streamflow is so strong that many of the levees are experiencing more stress than they can handle.

The pictures from Minot, ND have been incredible over the past 48 hours.

January Thaw (Sort of…)

Don’t get too excited. The thaw probably won’t last longer than a day and don’t think you’ll be able to head out and play some frisbee either. A burst of heavy rain will accompany the brief thaw before we cool down again.

Our computer models are honing in on an “inside runner” storm for next Tuesday. Though this will likely start out as snow or ice it looks like it will flip to rain everywhere with a track west of Connecticut. Thankfully we are not talking about enough rain or warmth to cause flooding (like January 1996) but the snowpack will certainly take a beating.

No sustained period of above normal warmth seems likely in the near future.