Bomb Cyclogenesis: Blizzard of '66
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what is the bomb? case study 1 case study 2 case study 3 the page of reference


[Case Study 2]

{The Blizzard of '66: January 1966} [12]

[-background information-]

_____This storm occurred over a three-day period from the 29th to 31st of January 1966. It was the third and most intense in a series of storms that hit the Mid Atlantic coast over a ten-day period. The heavy snow combined with temperatures that fell below -10 Celsius and wind gusts in excess of 25 m/s. The snowfall from the cyclone also combined with lake effect snow to leave 150 to 250 cm of snow to the region immediately to the south and east of Lake Ontario. Regions receiving at least ten inches of snow stretched from Virginia up into Maine. The snowfall exceeded the 20 inch mark in central New York, reaching 39.0 inches in Syracuse.

[-surface happenings-]

_____The cyclone associated with this storm developed along the edge of a large cold air mass that coincided with a 1055 mb high located over northern Canada. A weak inverted trough developed along the west side of the lower Appalachians early on the 29th and this helped set up cold air damming across the southeast US. With this damming, a coastal front developed just off the coast in this area. The surface low moved at a rate close to 15 m/s along the Gulf Coast. It redeveloped northeast of the coastal front late on the 29th and began moving at a more rapid rate of 25 m/s. Deepening was initially slow throughout the afternoon of the 29th. The low passed east of Cape Hatteras and then took a northerly turn. In a span of 18 hours starting at 00Z on the 30th, the low deepened from 997 mb to 970 mb, thus meeting the requirements for bomb status. The associated storm then moved inland across New Jersey, New York and western New England. With this northerly track, temperatures across the Mid Atlantic states never rose a significant amount about -10 Celsius. A fairly intense sea-level pressure gradient formed west and north of the low's center, creating a period of prolonged high winds in the area even long after the low pressure system had passed.

[-going up? 500 mb and the upper-level jet-]

_____There was a "major reorientation" of the upper-level features during the cyclogenesis event. The trough that was located in the southwest US appeared to "phase in with the elongated east-west vortex near the Canadian border as it split into two separate vortices." The two associated trough systems merged and the amplitude of this system increased substantially from 12Z on the 28th to 00Z on the 30th. The maximum deepening of the surface low occurred as the diffluence downwind of the trough became better defined. The 500 mb vortex that sat over the eastern US developed a highly negative tilt by 12Z on the 30th as the intensification of the surface low continued. The vortex continued to deepen to a significant level over the next 12 hours.

_____AOn the 29th a polar jet streak at the 500 mb level that contained wind speeds of 50 m/s moved from the Northern Plains into the Gulf of Mexico. At the same time at the 200 mb level, a subtropical jet that extended across the southeast US intensified and this coincided with the early stages of the cyclogenesis event. Associated wind speeds increased from 70 to over 80 m/s during this period. Immediately prior to the rapid cyclogenesis, a jet streak with winds of 80 m/s developed at the 300 mb level across the Mid Atlantic and New England states. A 60 m/s polar jet that stretched across the northeast US was associated with the massive cold air out break across the Eastern states before the cyclogenesis event.

500 mb Heights and Upper-Level Winds

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