Major Snow Storm
It was perhaps the cruelest twist of weather to affect the region during April 2000. A spectacular mid 70 degree day preceded the largest snowfall of the entire winter season in the Capital Region and the second heaviest all time April snowstorm on record. As if the snow was not bad enough, the magnitude of the storm came with very little warning. Forecasts on Saturday, the 8th, for the region had called for a period of rain changing to a brief period of snow through Sunday morning with only a couple of inches of accumulation expected mainly in the higher elevations. The following is a case account of what transpired to produce the big snow.
A strengthening trough of low pressure at the jet stream level was developing in the Midwest on Saturday, April 8. As a result very cold air was allowed to pour into the upper Mississippi valley behind a developing surface storm that was located in central Ohio. Over the Southeast and mid Atlantic, unusually warm air had developed and was being forced northward by the counter clockwise circulation around the Ohio cyclone. The occurrence of very large temperature contrasts fueling big storms in April is not unusual.
By 8:00am Saturday morning, April 8, the cyclone had moved to near Erie, Pa with a secondary low developing over West Virginia. A warm front, at this time, was moving through eastern New York and New England. Temperatures steadily climbed through the 60's and 70's in the warm sector of air over the Capital Region and New England during the morning and afternoon on Saturday, April 8. Strong southerly winds up to 40 mph aided in the transport of the warm air northward. Simultaneously, in the cold air across western New York, temperatures at Buffalo had fallen into the 30's and snow was developing. Through Saturday, areas of low pressure continued to organize on the boundary separating the exceptionally mild air over eastern New York and very cold air over western New York producing a mixture of rain and snow over western New York and maintaining the sunny warm conditions over eastern New York and New England.
By 2pm Saturday, clues were beginning to develop which might have suggested a much greater snowfall than was forecast for Sunday, April 9. At the jet stream level a strong disturbance was diving southeastward into the base of the large scale trough that was now digging into the Southeast. This jet stream disturbance was forcing a new surface storm to form on the cold front over western South Carolina. This ultimately would be the storm to produce the heavy snow over eastern New York and western New England.
In the meantime over the Northeast, the cold front continued to steadily progress across the state, preceded by a few widely scattered showers and thunder showers through the afternoon and early evening. The front passed Albany at approximately 6pm on the 8th, dropping the temperature from 76 at 6pm to 57 degrees at 6:15pm to 50 degrees at 7:30pm and to 39 degrees at 11pm. Steady rain did not develop until well after the front had moved east of the region, shortly after midnight on the 9th.
At this point in the forecast, it was anticipated that the cold front would continue to be progressive in nature and the storm that had formed over western South Carolina would be weaker and move much further east, off of Nantucket by Sunday morning, than what actually occurred. The jet stream disturbance, as it turned out, was much stronger than anticipated and thus was able to bend the main steering flow up the Atlantic seaboard from its southwest to northeast direction on Saturday the 8th, to a more due south to north configuration by early Sunday morning the 9th. With a due south to north flow, the cold front which had moved through the Capital Region, delivering the very cold air, lost it's atmospheric push to keep it moving east. With the front now parallel to the upper air flow, it stalled over the Connecticut river valley in west central, MA. The stalled front then acted as a highway for the Carolina low pressure system to cruise north along and intensify. And that is exactly what happened. As the low tracked along the front and grew stronger it induced a stronger northwest airflow over eastern New York which allowed even colder air to move into the region changing the rain over to snow by about 3am on the 9th. The low then transported a hefty slug of Atlantic moisture over the cold dome over New York which translated into a period of extremely heavy snow over the Mohawk valley, Adirondacks and Capital Region, as well as western New England well into the afternoon on the 9th. Snowfall rates exceeded two inches per hour for a time early on Sunday morning. By 8am on the 9th the storm was located near Worcester, MA producing the blinding snow over the Capital District. The system began to accelerate by midday Sunday, as the parent jet stream disturbance moved out, finally bringing an end to the snowstorm.
This storm is an excellent case example of how only a subtle change in air flow at the jet stream level in the atmosphere can result in such a dramatic change in an anticipated weather pattern and support such a dramatic snowfall when little snow was originally expected. On post analysis of the event, the available data through Saturday evening, the 8th was not sufficient to support a forecast of heavy snow for eastern New York and western New England. New observational data which became available by 10:45pm on the 8th began illustrating the magnitude of the jet stream disturbance that went on to shift the flow along the Atlantic seaboard. Forecasts were amended during the pre-dawn hours to illuminate the heavy snow threat. Unfortunately, at the late hour, most people were asleep and could not be advised of the change. Hence, most woke to a big white surprise the morning of the 9th.
The heavy wet snow which amounted to well over a foot in many locations, combined with a soft, unfrozen ground, and high winds, to result in many downed trees and power lines throughout the region. As many as 30,000 people in the immediate Capital District were left without power.
The following table is a listing of Channel 6's exclusive WeatherNet 6 weather watcher snow accumulations. Counties are alphabetized and color separated from top down.