The Giant 1969 Memorial Day Weekend Storm

Until yesterday if you asked me about the year 1969 the only things that would probably come into my head were Hurricane Camille, the moon landing, and Woodstock. Am I missing anything else?

Well it turns out I am! Yesterday I was going back through some of my geeky weather archive sites to figure out how often New London County has received significant (>2″) hail. As it turns out there have been only 2 cases of significant hail in New London County since 1955 – one in 1969 and another in 1995 during the super hail storm. The 1969 report from May 29th (the day before Memorial Day) is of baseball size hail in Groton. You don’t see that everyday! Here’s how Storm Data described the 1969 thunderstorm in Connecticut.

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The reports from Rhode Island and Massachusetts are equally as impressive.

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Radish size hail in Pawtucket – I love it! The storms obviously were quite intense given the dramatic descriptions in Storm Data. The weather pattern that day was favorable for severe thunderstorms – and one of those rare days where southeastern Connecticut was in the running for a violent evening storm.

Windsor Locks reported a sustained wind of 37 mph from the northeast during the storm with about 0.50″ of rain. Little rain fell in New Haven or Bridgeport – it would appear the storm missed them to the east.

In some of the cooperative weather reports from the Memorial Day morning you can get a general idea of where the storm(s) tracked.

  • “Trees and limbs” down in Brooklyn with a power outage and 0.56″ of rain
  • 0.23″ rain and thunder reported at the Cockaponset Ranger Station
  • 0.44″ of a “hard rain” along with thunder and hail in Colchester
  • 0.86″ of rain with thunder and hail in Groton
  • 0.86″ of rain at Pachaug State Forest

The morning weather balloon launch from JFK Airport in Queens showed very steep mid level lapse rates. The 500-700mb lapse rate was an impressive 7.9 C/KM! The weather map for 5/29/1969 showed a deep closed low over the Canadian Maritimes with a fast northwesterly flow through the mid troposphere. The JFK weather balloon data shows a northerly wind at 700mb of 46 knots.

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There was also a fairly impressive backdoor cold front bisecting New England. While winds were generally out of the west and northwest in Connecticut during the day the winds were due east at Logan. The high temperature at Logan was only 72F while it was 86F at Worcester and 92F in New Haven, Bridgeport, and Bradley. Eastern New England can really suck in the spring!

The air was also quite sticky over Connecticut. By mid afternoon Bridgeport had a dew point of 68F with 92F on the thermometer. The combination of the moist and hot boundary layer and steep mid level lapse rates likely set up a very unstable atmosphere over western New England. While this is only conjecture (since I don’t have the data) one can envision severe storm initiation near the backdoor front as a shortwave raced south on the strong northwesterly flow aloft to get things going. The strong mid level flow also cranked up fairly impressive deep layer shear – a requisite for organized severe convection.

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As it turns out this kind of setup is not unusual for severe weather in Connecticut. We’ve seen cases before where an elevated mixed layer (characterized by steep >8.0 C/KM lapse rates) have advected eastward along the US/Canadian border and have helped spawn severe weather in New England with deep northerly/northwesterly flow.

The 1995 hail storm comes to mind as one example of this. The storm occurred near a backdoor cold front. This storm was able to drop base ball size hail (for 20 minutes!!!!) in Deep River. The northerly/offshore flow can help keep the shoreline unstable and hold the marine influence at bay. You can see a similar setup here with a deep low over the Canadian Maritimes and northwest flow across New England.

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It also is somewhat similar to the May 26, 2010 overnight severe weather event that managed to drop hail to ping pong ball size in Bridgeport in the middle of the night.

The offshore wind component is necessary for big severe storms in southeastern Connecticut. This is especially true around Memorial Day when water temperatures are still quite chilly.

I love looking back through old weather data to learn about storms I have never heard of and also how meteorologists and others described the weather back then. The “radish” size hail description in Pawtucket, RI was a new one for me. I may have to snag that one for myself next time we’re doing storm coverage. A Twitter follower wrote this to me last night after I tweeted about the radish size hail report. He nailed it – and made me laugh too.

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One other interesting note from the May 1969 storm data report that caught my eye. On May 3rd around 3:30 Grosvenordale had one freaky storm…

Screen shot 2013-09-04 at 11.03.46 AMI’ll take their word for it.

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New London County Hailstorm

Hail (and a screw driver) from Mark in Preston

Hail (and a screw driver) from Mark in Preston

When you think of severe weather in Connecticut you probably don’t think about New London County. The southeastern corner of the state is a pit for snow and 99 times out of 100 is where thunderstorms go to die. With the exception of hurricanes – weather weenies in New London County are used to let down after let down after let down.

Today, however, brought a severe storm bonanza to New London County. 3 separate storms brought severe hail to New London County including a report (and picture to go along with it!) of significant hail (hen egg size) in Ledyard.

2" diameter hail in Ledyard

2″ diameter hail in Ledyard from Josh

The severe weather threat today was a bit nebulous but still well forecast. A cold front had bisected the state by midday with a narrow corridor of marginal/moderate instability juxtaposed with fairly strong deep layer shear. Here’s the 18z RAP sounding for Groton around the time of the largest hail reports.

RAP BUFKIT analysis at 17z

RAP BUFKIT analysis at 17z

Dew points over 70F were underneath steep mid level lapse rates – on the order of 7.2 C/KM between 500 and 700mb. Impressive! While MLCAPE values were only around 1000 j/kg a fair amount of that CAPE was located in the hail growth zone (-10 to -30C) and 0-6km shear values were near 40 knots.

It shouldn’t come as a surprise that many of these storms exhibited mid level rotation and the mesocyclones were able to sustain some pretty impressive hail stones. I’ll also throw this out there that the models today were consistently underdone with progged CAPE values today. For example, the 12z OKX sounding had 2500 j/kg of CAPE which was far higher than model forecasts or even 12z model analyses. It’s conceivable that the 1000 j/kg of MLCAPE analyzed at 18z on the RAP may have also been underdone compared to reality.

Handfulls of quarter size hail in Groton

Handfulls of quarter size hail in Groton

The storm that dropped the largest hail pulsed up shortly before 2 p.m. over Montville and the Thames River just a (hail)stone’s throw from Mohegan Sun. The 1754 UTC volume scan from OKX shows an impressive hail core with 65 dbz echoes up to the -20c isotherm (over 20,000 ft AGL) and 72 dbz around 10,000 ft AGL.

1754 volume scan KOKX 88d

1754 volume scan KOKX 88d

While meteorological echoes (part anvil being blown northeast by 70 knot southwesterlies near the Equilibirum level and part other junk) masked the hail spike on the OKX radar but the radar out of Taunton showed an impressive (spatially and vertically) three body scatter spike.

KBOX 88d correlation coeffecient - note blue shading southwest of storm showing hail spike

KBOX 88d correlation coeffecient – note blue shading southwest of storm showing hail spike

Shortly after the storm pulsed over Montville the core of the storm dropped and so did golf ball and hen egg size hail in the far northwest corner of Ledyard near the Thames River and along and west of Avery Hill Road just south of Route 2A. Dual Polarization products showed the hail core descending with a clear signal of hail in Ledyard by 1758 UTC (at 4500 ft AGL).

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1758 UTC KOKX volume scan. Clockwise from top left – 0.5 degree base reflectivity, correlation coefficient, specific differential phase, differential reflectivity

Within an area of high reflectivity (Z between 50 and 60 dbz) you can see a noticeably depressed area of correlation coefficient – in some cases near 0.90. There are also areas of ZDR near zero or even subzero which shows that hail is dominating the signal (hail tumbles as it falls so appears spherical to dual pol radar which leads to a differential reflectivity value near 0).

One thing that’s somewhat interesting is that the southeastern part of the storm has very high KDP values – nearly 4 deg/km while the northwest part of the storm was much lower. While the hail signal was present throughout this region the spike in KDP over the center of Ledyard may indicate a lot of water coated sub-severe hail while the lower KDP over the Thames River and northwest Ledyard in the hail core was where the larger/non-water coated hail was falling. Indeed, this matches up with the reports we received of hail near (or even over) 2″ on the Thames River in far northwest Ledyard with dime to quarter size hail in the center of town.

Golf ball size hail in Ledyard melted to this size about 10 minutes after it fell. Thanks Tom for the picture!

Golf ball size hail in Ledyard melted to this size about 10 minutes after it fell. Thanks Tom for the picture!

I went back and searched through SPC’s storm database and then double checked some of the events in NCDC’s storm data. It appears that the 2″ hail from Ledyard is the largest hail event reported in New London County since 2″ hail was reported in Old Lyme during the 1995 super hailstorm. Incidentally, the largest hail report I can find in New London County was from Groton in May 1969 where baseball size hail was reported. 2.75″ hail (baseball size) only shows up 4 times in the Connecticut SPC storm event database since 1955 and 3 of the 4 were from 1995 and all have been along or east of the Connecticut River.

Hurricane Carol – The Monster of 1954

Hurricane Carol in Groton Long Point (photo credit http://www.tedknowlton.com)

Hurricane Carol in Groton Long Point (photo credit http://www.tedknowlton.com)

Hurricane Carol was one hell of a storm. The category 3 hurricane made landfall near Groton and brought devastating flooding and wind damage to parts of southeastern Connecticut and Rhode Island (from South County to Providence). Carol is a bit forgotten – the impact was less than 1938 and it was overshadowed in the state by the remnants of Connie and Diane in 1955 that paralyzed the state with a biblical flood.

The reanalysis by Chris Landsea and the work by Jarvinen shows a landfall of Carol near Groton. This is about 20 miles east of the “Best Track” landfall location in Old Saybrook. The reanalyzed landfall location makes sense given the damage documented in Connecticut.

Hurricane Carol reanalyzed track and wind swath (Landsea et al.)

Hurricane Carol reanalyzed track and wind swath (Landsea et al.)

Carol made landfall on the morning of August 31, 1954. The storm brought category 2 force winds (sustained near/over 100 mph) in Groton and Stonington and a vicious storm surge. In New London the storm tide reached 9.6 ft MLLW, only exceeded by the 1938 storm which was 10.6 ft MLLW. The surge in New London at the tide gauge was 6.5 feet though a study by the Army Corps of high water marks after Carol revealed surges of 8-10 feet were common throughout southeastern Connecticut. In Stamford – many miles from the landfall location – the storm tide reached 10.3 ft NGVD which was only exceeded by Sandy and the 1938 hurricane.

Hurricane Carol in Connecticut (NOAA)

Hurricane Carol in Connecticut (NOAA)

Hurricane Carol is widely viewed to be the “most tropical” of hurricanes to hit Connecticut. What’s meant by that is that while the storm was likely going extratropical transition – Carol was the most purely tropical of the storms to strike Connecticut. Here’s one example of that – take a look at this picture taken from the old Griswold Hotel in Groton near the mouth of the Thames River.

Flooding during the eye of Carol (Courtesy: Town of Groton)

Flooding during the eye of Carol (Courtesy: Town of Groton)

The storm had a classic “eye” and the precipitation distribution from the storm – both east and west of the storm track – was relatively symmetrical. That’s very unusual for a landfalling New England hurricane!

In Bridgeport the monthly climate report indicates 1.62″ of rain fell on the day with a peak sustained wind out of the NNE at 40 mph with a gust to 60 mph. The report read as follows “Hurricane Carol did extensive damage to the shorelines of Connecticut. Storm center passed 50 miles east of station. Lowest pressure noted at 0920 EST, with NNE winds of 40 MPH and gusts to 60 MPH noted at 0928 EST. Airport was inundated with a maximum of 2 feet of water.” The lowest pressure reading in Bridgeport was 28.87″.

In Hartford at Brainard 2.36″ of rain fell. No wind data was recorded. In New Haven at Tweed 2.63″ of rain fell with a sustained wind of 38 mph out of the northeast. The report read “Heavy storm on the 31st. Gusts to 65 MPH 9-10 A.M. Caused heavy water manage along shore. Lowest pressure 28.77″ 9:10 A.M.”

At Windsor Locks 1.95″ of rain fell with a suatained wind of 56 mph out of the northwest! A 64 mph wind gust was recorded in the monthly report.

Cooperative observer reports for August 1954 include some interesting highlights.

  • Baltic, CT recorded 4.10″ of rain “HURRICANE” was listed in the important wx conditions space.
  • Brooklyn, CT recorded 4.00″ of rain
  • The observer in Colchester wrote a great blurb about Carol – though I can only decipher about half of it! colchester
  • The Danbury coop observer reported wind gusts near 60 mph
  • In Derby the coop observer reported the following “High winds on Aug. 31. Hurricane “Carol” considerable damage to trees. An additional amount of rain – 1.05″ fell from 8:30 a.m. to 12:30 p.m. on Aug 31″ That 1.05″ is in addition to the 1.56″ reported at 8:30 a.m. in Derby.
  • Even in Falls Village the observer mentioned the wind on the 31st “wind on the 31st caused considerable damage to untilities.”
  • In Groton the observer wrote “Aug 31. Winds of hurricane force from 9:00 A.M. to 11:30 A.M. did much damage to buildings, trees, and boats in this area. Power and telephone lines severely damaged causing loss of service for several hours.”
  • In Mansfield at the dam the coop observer from the Army Corps mentioned on the 31st “Note: temperature readings may be inaccurate because the box blew over during height of storm”
  • Here’s what the Middletown observer wrote: middletown
  • Here’s the observer’s remarks in New London at Fort Trumbull. newlondon
  • In Norfolk, observer Norman Smith summarized Carol this way, “The feature of the month that was most notable was the passage on the 31st of an Atlantic hurricane. The storm here brought 2.59″ of beneficial rain with shifting gale winds from the E NE and NW. There was some damage to power and telephone lines and roads were blocked by uprooted trees and branches.”
  • In Putnam 4.25″ of rain fell and the observer noted the hurricane passed east of Putnam with considerable damage to crops and trees with some property damage.
  • In Storrs 3.35″ of rain fell. The observer wrote, “On the 31st of August Hurricane “Carol” hit eastern Connecticut hard with 60 mile wind – higher gusts – and nearly 2″ of rain between 8 and 11 a.m.
  • 4.36″ of rain fell in Westbrook – here’s the observation remarks.westbrook

The observations show a core of very heavy rain – 4″-6″ of rain near the center of the storm with less rain on the western periphery. Again this symmetry is unusual and shows that the eyewall was likely quite in tact and the storm was still quite “tropical” at the time of landfall.

Carol produced $50,000,000 in damage in 1954 dollars in Connecticut and killed 65 across New England.  The storm is the only category 2 to strike Connecticut in modern times (1938 was a category 3 in Connecticut) and remains the strongest storm to strike the state in the last 59 years.

Too Many Fronts

OKX Base Reflectivity Courtesy of WeatherTap, Click to Animate

This is pretty cool stuff for a weather geek. Take a look at the echoes racing west across Long island Sound. That is a backdoor cold front with a strong wind shift behind it and rapid temperature drop. The wind at Bridgeport is north at 15 mph and the temperature is 78º while the wind in Groton is southeast gusting to 32 mph and the temperature is 62º!

There’s another front on there and that a sea breeze front that has developed basically over New Haven Harbor and extends northeast into North Branford, Durham, and Killingworth with southerly winds behind it and northerly winds ahead of it.

One of the reasons the backdoor front has taken on a “C” shape is that less friction over the water has allowed the winds to be faster over the Sound than over land which is effectively bulging the front west in the water.

The echoes to the west over New York are showers falling from a mid level cloud deck that are evaporating before reaching the ground.