Monday, July 10, 1989
Northeast Severe Weather - Tornado Outbreak
(Montgomery-Schoharie-Albany-Greene County Damaging Tornado Family)


Written March 15, 2016
Steve LaPointe - CBS6 Chief Meteorologist


Overview
The July 10, 1989 major severe weather outbreak not only impacted the local area with tornadoes, hail, damaging straight line wind and torrential rain but also spread pockets of heavy damage across communities in four other Northeast states as well including Pennsylvania, New Jersey, Massachusetts and Connecticut. Regionally, seventeen tornadoes, two of which were classified as violent with winds over 160 mph (one in Schoharie County), were confirmed as well as over fifty reports of straight line wind damage, fourteen of those produced by winds of 80 mph or higher. Additionally, there were ten reports of hail greater than 1" in diameter with hail up to 2.5" diameter measured. There were many injuries, but fortunately no fatalities resulted from the storms.

The remarkable meteorological aspects and ensuing events of the day remain as clear in my mind today as they were on July 10, 1989 even though it was a few years before my time at WRGB. I was then close to finishing my undergraduate meteorology degree at Penn State and was participating in a summer internship at WNEV TV channel 7 in Boston (now WHDH TV). I was a forecaster in my role at WNEV and had actively forecast this event and watched my predictions of significant severe weather in New England come to fruition. Ultimately I completed a research case study on the meteorological conditions which came together to produce the severe weather and included that analysis in my college internship report which was required to gain credit. It's from this internship report, my memories, and information on the event which was saved by either John Cessarich or Neal Estano (the meteorologists at WRGB here at the time) that I put this historical look back together for inclusion in the CBS6 climate and storm summary database.

July 11, 1989
Schenectady Gazette headline and article detailing the significant storm damage in Schoharie County
Photo credit: Sid Brown


Schenectady Gazette Headline July 11, 1989


Long Track Supercell - Violent Tornado
(S
trongest on record in NY to date with an F-4 (Today's scale EF-4) rating (winds of 166-200 mph)
The event locally is remembered for the long track supercell thunderstorm which went on to produce what was likely a family of tornadoes, vs a single one, as it tracked southeast from near Ames in Montgomery County through northeast Schoharie, southwest Albany and northwest Greene counties. The storm continued on a southeast path through Columbia County where widespread damaging straight line wind occurred. The supercell then moved into and through Litchfield County, CT where additional tornadoes developed on its path into New Haven County, CT where two more tornadoes touched down, one of them also an F-4 in Hamden, CT. The storm continued onto Long Island where another strong tornado (F-2) touched down in Moriches.

From Wikipedia: Storm Reports for the July 10, 1989 Outbreak
Red dots and lines indicate the tornado tracks
Blue plus signs are wind damage reports
Green dots are large hail reports


Schenectady Gazette Headline July 11, 1989

Albany NWS Tornado Report: Issued 7:05pm Tuesday July 11, 1989

Tornado #1: 2:37pm to 3:25pm
Tornado began in Ames, Montgomery County at 2:37pm terminating in Schoharie, Schoharie County at 3:25pm
Path Length: 24 Miles
Path Width: 1/2 to 3/4 mile
Rating: F-4 (Winds of 165 mph or greater)
Description
The tornado damage path indicated the storm skipped along the ground with the greatest damage occurring near the intersection of Wetsel Hollow Road and US Rt. 7. Damage in this area was rated by the survey team to be F-4 (in today's EF scale, winds greater than 165 mph) Other damage along the path ranged from F-1 to F-3, indicating strong to violent rotating winds.

Tornado #2: 3:35pm to 3:40pm
Tornado began and ended within the village of Surprise in Greene County
Path Length: 1.5 Miles
Path Width: 11 yards
Rating: F-0 (Winds of 65-85 mph)
Description

The same parent supercell thunderstorm produced this second smaller tornado which touched down in Surprise causing damage mainly to trees

NOTE: It has been suggested by experts looking back at this event that this tornado's F-4 rating is more than likely a category high based on today's standards of storm damage evaluation and that a rating of F-3 is more appropriate. (The 1998 Mechanicville-Stillwater and 1995 Great Barrington, MA tornadoes are rated F-3 for perspective.)

Area of Greatest Impact - Schoharie County - Carlisle - Howes Cave - Schoharie

We learn more about the impacts of the tornado from a Schenectady Gazette report. Staff writers filed the following:

"The heart of yesterday's powerful storm ripped a ten mile long swath through north-eastern Schoharie County, destroying at least ten homes and injuring at least eleven people."

Additionally,

"The short-lived storm hit about 3pm, apparently hitting with the most ferocity in a line from Crommie Road in Carlisle through the Howe Caverns estate, Howes Cave hamlet, Wetsel Hollow, petering out in or about he village of Schoharie. Scores of trees and large limbs were brought down, several garages were blown clean away, and garages, barns and houses were damaged or even demolished. Power was off from Howes Cave to Middleburgh, but telephone services were apparently largely intact. Deputy emergency management director Charlie Stanton said, seven or eight homes on Crommie Road in Carlisle were destroyed. That area, about five miles northeast of Cobleskill is apparently about where the major damage started. From there the big blow headed southeast to the Howes Cave area. There, on Barnerville Road, half a barn and silo were down, a two car garage blown away and other barns and garages damaged or destroyed. The road was closed with numerous limbs and trees across it. In the Howe Caverns parking lot, a motor home about 24 feet long was blown from the parking lot into the woods and overturned, and a Dodge minivan was rolled over the tops of several other vehicles, according to William Romain, whose wreckers were called to tow the vehicles. From that area, said Livingston, the storm continued southeast to Wetsel Hollow at Route 7 where a house owned by Robert and Betty Brazie was lifted off its foundation and moved onto Route 7. Numerous houses in the Wetsel Hollow area were said to be heavily damaged or destroyed. Crossing I-88 a barn was lifted and blown apart into a van on the superhighway. Then, the storm proceeded up Wetsel Hollow Road to Schoharie Hill Road and on to Sodom and Sunnyside roads where numerous trees and limbs were reported down, roofs blown off and houses damaged. Proceeding into Schoharie village down Bridge Street to Main Street, the storm took down dozens of large limbs or trees, felled a large barn at Guernsey's Schoharie Nurseries, but left plastic-clad greenhouses in tact. At least two garages were destroyed and a big top tent erected in the supermarket parking lot for a firemen's weekend carnival was flattened."

Despite some controversy concerning the ultimate rating of this tornado, it is one of if not the strongest on record in New York certainly on par with the Mechanicville-Stillwater tornado in May, 1998, a storm which hit a more densely populated area resulting in more significant damage. Tornadoes of this magnitude are rare in the Northeast and the Schoharie County storm on July 10, 1989 is a testament to the strength of the meteorological players at work which all came together at just the right time to set the stage for the outbreak.

The Meteorology
The outbreak occurred in a classic northwest jet stream flow pattern, where the main steering wind aloft was from Northwest to southeast with low level winds from the south-southwest, establishing a highly sheared environment in not only direction but in speed as well. This type of set up (as strong as it was on this date) is fairly rare in the Northeast but when it occurs in conjunction with other favorable parameters often does result in significant severe weather.

A strong surface a strong warm front, accompanied by heavy rain and thunderstorms during the morning, moved quickly from west to east across eastern New York and western New England allowing a surge of tropical moisture into the region. I remember taking calls in the WNEV weather center early that afternoon from viewers wondering why their windows and mirrors had quickly fogged over. This glass fogging was an indication of a significant moisture surge which the surface weather observations confirmed. Dewpoints jumped from the low and mid 50s during the morning on the east side of the warm front into the low and mid 70s immediately after the frontal passage all in less than an hour. It was surface moisture convergence like I had never observed myself before and proved to be a key ingredient in fueling the severe weather yet to come later in the day.

11am Surface Analysis, July 10, 1989 showing the passing warm front across eastern New York attached to an approximately 1000mb low in the St. Lawrence valley with a strong cold front approaching western New York. The area between the inbound cold front and eastward moving warm front is called the warm sector. It's in the warm sector that the air has the potential to become unstable given other favorable conditions and is thus the region where severe weather is most likely in a spring or summer set up.

11am Surface Map, July 10, 1989 

Aloft, the jet stream was unusually strong for the time of the year with anywhere from 90 to 105 knots (104 to 120 mph) of northwest wind at the 300mb to 200mb levels (roughly 30,000' to 39,000') and up to 70 knots (80 mph) of wind from the WNW moving over and still moving into the region at the 500 mb level (roughly 18,000'.)

8am July 10, 1989 200 mb Chart (Roughly the 39,000' level) illustrating the powerful jet max (105 knots or 120 mph) moving over eastern New York and New England


200 mb chart July 10, 1989

8am July 10, 1989 300 mb Chart (Roughly the 30,000' level) illustrating the powerful jet max (90 knots or 104 mph) moving toward eastern New York and New England

300 mb chart July 10, 1989 

8am July 10, 1989 500 mb Chart (Roughly the 18,000' level.) The solid color lines are the heights of the 500mb pressure level. Notice how the lines tend to fan away from each other over New England, southeast New York and New Jersey. This pattern is called a diffluent flow pattern and is conducive to venting the tops of thunderstorms aiding in their upward development. Also of note on this chart was the powerful core of the 70 knot (80 mph) winds observed from Sault Sainte Marie, MI to Albany. Wind of this magnitude is unusual for July and greatly aided in increasing the shear and overall energy for the violent weather which ensued later in the day.

500 mb chart July 10, 1989 

8am July 10, 1989 700 mb Chart (Roughly the 10,000' level.) showing pronounced mid level drying over the region noted by dewpoint depressions of of 15° at Buffalo. Mid level drying is a favorable ingredient for severe wind gusts in thunderstorm downdrafts as some evaporation of rainfall occurs at it falls through the drier layer causing that layer to cool and thus descend to the ground more rapidly enhancing the gust potential at the surface. Winds at this level on this chart were also strong from 30-40 knots on average.

700 mb chart July 10, 1989

8am July 10, 1989 850 mb Chart (Roughly the 5,000' level.) showing considerable warming at this level with a strong wind max of 40-50 knots approaching from Detroit and Buffalo, both strongly favorable ingredients for severe thunderstorm development

800 mb chart July 10, 1989


8am NGM (Nested Grid Model) heights and vorticity analysis July 10, 1989. This is a technical forecast chart from a now long retired numerical forecast model. The panel illustrates the height of the 500mb pressure level (dips in the lines indicate pockets of colder air aloft.) This panel also shows a strong (22 unit) vorticity maximum tracking across southern Canada. (Vorticity is a measure of the curl or spin of the air. The stronger the value the greater the spin and thus the greater the potential for stronger upward vertical velocities on the eastern side.) The zone I have shown in red indicates the zone where the vorticity maximum is producing strong lift in the atmosphere, favorable for severe thunderstorm development in an unstable environment.

12Z NGM analysis July 10, 1089 

8am NGM analysis: MSP (mean sea level pressure) and 1000-500 mb thickness lines: This chart shows the passing surface low pressure system to the region's north as well as a strong warm advection pattern through the morning. The coupled effect of the strong low level warming and cooling aloft along with the exceptionally strong jet stream winds which were both veering and increasing in speed with height set the stage for explosive thunderstorm development through the day, with the triggering mechanism being the leading edge of the cooling aloft and a surface convergence boundary (pre-frontal trough) running in advance of the cold front.

12Z NGM analysis July 10, 1089 

5pm Surface Analysis July 10, 1989: This final chart shows the position of the surface features at 5pm across the region. Severe weather was exiting eastern New York at this time with some sunshine developing and a spike in temperatures into the low 80s. The the main axis of supercell thunderstorms (three of them) were lined up along the pre-frontal trough (black dotted line.) across New England. These storms were all producing periods of damaging wind, large, hail, and tornadoes along their paths. Even a gust to 60 mph on Cape Cod was reported as the final storm moved off shore during the evening. (The dewpoint at Albany spiked to 76° around 6pm in advance of the cold front.)

5pm Surface Anlysis July 10, 1989 

Summary:
This event resulted from a case of all the classic ingredients coming together at the right time over the region to support the severe thunderstorm and tornado outbreak. The combination of exceptionally strong dynamics aloft (the combination of the strong jet stream winds at the various levels and cold pocket of upper level air moving into and through the region) coupled with a morning warm frontal passage and subsequent surge in surface heat and moisture allowed for strong differential advection to occur where the upper atmosphere cooled while the lower atmosphere warmed. The differential advection caused explosive instability even without the benefit of full surface heating as sunshine was limited due to extensive cloud cover left over from the morning heavy rain along the warm front. Surface low pressure tracking to the north of the region induced a southerly low level flow, which may have been enhanced by the local terrain where the Schoharie Creek and Mohawk river come together, to allow for enough low level spin to develop for the tornado to form from the parent supercell circulation near Ames in Montgomery County. The pre-frontal trough was also key as it acted as a convergence boundary for the thunderstorms to form with a then rapid northwest to southeast motion due to the speed of the upper level steering flow. It's not often in the Northeast that all of these parameters come together at these strong magnitudes to produce this level of organized severe weather. But, it does happen from time to time. It is interesting to note, that the Storm Prediction Center issued a severe thunderstorm watch for eastern New York and southern New England for this event, and not a tornado watch.