Tuesday November 30-Wednesday December 1, 2010
Heavy Rain-High Wind Event

A two day rain event culminated with the passage of a strong convective rain band Wednesday afternoon, December 1 which was accompanied by wind gusts ranging from 30-50 mph. Two day combined event rainfall totals ranged from 1.50" to 2" throughout the region with pockets of 2" to 2.5" and a jackpot of 3" to 5" in terrain favored areas of Greene County with just under 7" reported in Phoenicia in Ulster County where a prolonged period of SSE upslope flow effectively enhanced the rainfall. Much of the storm total rainfall fell in a two to four hour window with the passage of a powerful cold front on December 1. Widespread urban and poor drainage flooding occurred as well as minor to moderate flooding on many area streams and creeks, with major flooding reported along portions of the Esopus Creek in Ulster County.

Strong SSE gradient winds, gusting up to 40 mph in the valleys and up to 60 mph at elevations of 2000' and higher, brought down trees and power lines leading to scattered to numerous power outages throughout eastern New York and western new England during the day.

The following images were taken from Instant Doppler 6 showing the progress of the intense rain band that was directly tied to the passing cold front. This rain band moved through the immediate Capital Region during the mid afternoon, passing over the WRGB facility in Niskayuna, NY at 3pm with torrential rain and a prolonged period of high wind.

Instant Doppler 6 Image: 2:26pm, Wednesday December 1, 2010
Torrential Rain band moving into the Capital Region

Instant Doppler 6, 2:26pm, Wednesday December 1, 2010 

Instant Doppler 6 Image: 2:51pm, Wednesday December 1, 2010
Torrential Rain band moving into the Capital Region

Instant Doppler 6, 2:51pm, Wednesday December 1, 2010 

Instant Doppler 6 Image: 3:29pm, Wednesday December 1, 2010
Torrential Rain band moving towards western New England

Instant Doppler 6, 3:29pm, Wednesday December 1, 2010 

Storm Scenario:
A full latitude trough at the jet stream level tracking east across the Country set-up a deep southerly flow of mild air up the Appalachians and Atlantic seaboard from November 30 through December 1. Extremely mild air briefly flowed into eastern New York and western New England Wednesday afternoon with temperatures jumping to around 60° and dewpoints climbing to between 50° and 55° between 9am and 2pm.

The combined circulations around strengthening low pressure tracking along a strong cold front through eastern New York and strong high pressure parked east of Maine on December 1, effectively channeled a feed of deep moisture flowing north from the Gulf of Mexico and off the Atlantic into eastern New York and western New England. The approach of the front and surface low pressure system along with a passing powerful upper level jet stream (130 mph) created substantial lift in the atmosphere to turn that moisture feed into the line of torrential rain that moved from the western Catskills and Adirondacks to Rutland, Bennington, and Berkshire counties between 1pm and 5pm. On average an inch and a half of rain fell in most areas in less than two hours, marking the majority of the storm total rainfall for the two day event. The release of such moisture in such a short time period produced a huge amount of runoff which lead to the widespread urban and poor drainage flooding, along with minor to in some areas moderate flooding along the smaller streams and creeks which occurred.

A temperature drop of roughly 20° occurred in less than thirty minutes with the passage of the front with a brief change to snow across the higher terrain in the Catskills on north through the Adirondacks. 1/4" of snow fell at Jefferson, with 1/2" reported at Indian Lake by our WeatherNet 6 spotters. Sleet briefly mixed in throughout the rest of the region as the precipitation quickly moved out during the late afternoon and early evening. This was a case where the deep moisture just barely outran air cold enough to support a widespread changeover to snow. Temperatures rapidly dropped into the 30s during the late afternoon and evening, with most areas, however, remaining above 32°, precluding any flash freezing, which can often occur in the cold season with strong frontal passages.

Wind:
High wind was an issue for the Northeast with this storm resulting from a tight pressure gradient which developed between the strengthening low which passed directly over the Capital Region and a strong area of high pressure parked just east of Maine. A low level SSE jet developed with winds up to 75 mph measured Wednesday morning into the afternoon at an elevation as low as 3000'. A 103 mph peak wind gusts was registered at Mount Mansfield, VT (elevation of 4393 feet) at 4:00pm. A temperature inversion, however, (warmer air on top of colder air) prevented much mixing of the powerful winds just off the deck down to the ground. Temperature inversions are typically present in strong cold season SSE flow situations as warm air floods into the region more readily aloft, than at the ground. Despite the inversion, frequent south to southeast 30-40 mph gradient wind gusts occurred through the morning and into the afternoon with peak wind gusts in many areas of 50-55 mph along the leading edge of the torrential line of rain associated with the cold frontal passage. The convective nature to the rain caused some mixing of the high wind aloft down to the ground, creating the brief period of enhanced wind along the leading edge of the heavy rain band, which lead to downed trees, power lines, and sent thousands across the region into the dark as the power went out. The west to northwest flow behind the storm was much weaker than the south to southeast flow ahead of the storm and therefore, the wind dropped off rapidly with the passage of the front with gusts dropping to around 25 mph during the evening, and speeds down to approximately 10-15 mph by midnight.

Wind-Storm Damage-Flooding Reports...These are reports used by the NWS to verify statements and warnings that were in effect at the time and do not therefore represent all of the wind damage and flooding that occurred across the region from the event

Town County Report Time
Old Forge Herkimer Wind Damage: Numerous Trees and power lines blown down 11:00am
Ohio and Russia Herkimer Wind Damage: Numerous Trees blown down 11:00am
Glens Falls Warren Peak Measured Gust: 43 mph 11:45am
Mohawk Herkimer Flash Flood: Six inches of water flowing over Route 5s 12:57pm
Cairo Greene Flash Flooding: Numerous roads reported closed 1:00pm
Kiskatom Greene Flash Flooding: Numerous roads reported closed 1:00pm
Lanesville Greene Flash Flood: Route 214 closed due to flash flooding 1:00pm
Windham Greene Flash Flood: County Route 12 closed due to flash flooding 1:00pm
Newport Herkimer Wind Damage: Power lines blown down on East Street 1:02pm
Greenville Center Greene Flash Flood: Scutt Rd. closed due to flooding 1:30pm
Palenville Greene Flash Flood: Pennsylvania Ave. closed 1:30pm
Mohawk Herkimer Flash Flood: Intersection of Hinman Rd. and Route 28 under water 1:40pm
Phoenicia Ulster Severe Flash Flood: Main street completely flooded, evacuations from the tailor park on Station Rd, Plank and Heardman Rds. closed 1:45pm
Shandaken Ulster Flash Flooding on SR 214, Silver Hollow Road, and Woodland Valley Rd. 1:45pm
Mount Tremper Ulster Section of Route 28 closed due to flooding 1:45pm
Middleville Herkimer Flash Flooding 1:45pm
Little Falls Herkimer Flash Flood: Mud slide closed route 5 in Little Falls 1:54pm
Sheffield, MA Berkshire Wind Damage: Large tree blown at intersection of Rt. 7 and Rt. 7A 2:15pm
Lee, MA Berkshire Wind Damage: Tree limbs down on Church, Fairview, and Summer Sts. 2:15pm
Rutland, VT Rutland Peak Wind gust of 56 mph 2:26pm
Albany Albany Peak wind gust of 51 mph 2:33pm
Fort Ann Washington Wind Damage: Open air bard destroyed 2:50pm
Beacon Dutchess Portion of a roof blown off a home on Rountree Court near Liberty St. 3:00pm
New Baltimore Greene Flash Flood: Route 61 closed due to flooding 3:00pm
Salem and N. Hebron Washington Wind Damage: Trees and power lines blown down 3:00pm
Cossayuna and Argyle Washington Wind Damage: Trees and power lines blown down, blocking roads 3:00pm
Bennington, VT Bennington Wind Damage: Trees blown down at various points across the city 3:00pm
Catskill Greene Flash Flood: route 30 closed due to flooding 3:00pm
Cairo Greene
Flash Flood: Water moving rapidly across Route SR 23
3:06pm
Bennington, VT Bennington Peak Wind Gust of 54 mph 3:21pm
Voorheesville Albany Measured wind gust of 51 mph 3:30pm
Schenectady Schenectady Flash Flood: Crane St. water rescue from a car, several feet of water on the road 3:30pm
New Salem Albany Wind damage: Power lines blown down 3:45pm
Malta Saratoga 55 mph Measured Wind Gust 3:50pm
Voorheesville Albany Peak Wind Gust of 51 mph 3:50pm
Cohoes Albany Flash Flood: Route 32 closed due to flooding 4:00pm
Claverack Columbia Wind damage: Stone Mill Rd. closed due to downed poles 4:00pm
Cairo Greene Flash Flood: Route 145 closed due to flooding 4:15pm
Ballston Spa Saratoga Trees blown down 4:30pm
Glens Falls Warren Wind damage: Tree fell across two homes causing damage to a porch and the roof of the home on Haviland Ave. 4:30pm

WeatherNet Storm Total Rainfall Reports from November 30-December 1, 2010
(Note: If the rainfall report is followed by a time, then the report is valid at that report time and not a full storm total)

Town County Rainfall Report Town County Rainfall Report
Pittsfield, MA Berkshire 1.45" Lanesborough, MA Berkshire 1.70" (5:46pm)
Sharon, CT Litchfield 1.71"      
           
Cohoes Albany 1.88" (6:18pm) Colonie Albany 2.24" (6:03pm)
Preston Hollow Albany 1.55" Coeymans Hollow Albany 2.25" (5:29pm)
Latham Albany 1.70" (5:07pm) Albany Albany (Airport) 1.97"
   
     
North Chatham Columbia 1.21" Kinderhook Columbia 1.59"
Ancramdale Columbia 1.30" Livingston Columbia 1.30" to 1.45"
Ghent Columbia 1.70" Chatham Center Columbia 1.20"
           
Broadalbin Fulton 1.80" Johnstown Fulton 1.95"
           
Elka Park Greene 5.73" Catskill Greene 1.88"
Maplecrest Greene 3.70" Freehold Greene 4.90"
Cairo Greene 1.50" Greenville Greene 3.63"
Leeds Greene 3.20" Jewett Greene 2.24"
Lexington Greene 3.64" Halcott Greene 2.37"
Haines Falls Greene 4.20"      
           
Wells Hamilton 2.97"      
           
Fonda Montgomery 1.43" Amsterdam Montgomery 1.20"
Hessville Montgomery 1.61" Stone Ridge Montgomery 1.90"
           
Oneonta Otsego 1.14" Cherry Valley Otsego 1.10"
Worcester Otsego 1.25" East Worcester Otsego 1.26"
           
Taborton Rensselaer 3.20" (4:52pm) Center Brunswick Rensselaer 1.68" (5:46pm)
Stephentown Rensselaer 1.30" (5:00pm) Speigletown Rensselaer 1.70" (4:55pm)
           
Charlton Saratoga 1.65" Wilton Saratoga 1.91" (5:05pm)
Mechanicville Saratoga 1.12" (5:02pm) Ballston Spa Saratoga 1.65" (4:59pm)
Corinth Saratoga 1.74" Malta Saratoga 1.70"
Ballston Spa Saratoga 0.61" Milton Saratoga 2.10"
Clifton Park (Oaks) Saratoga 2.07"      
           
Richmondville Schoharie 1.01" Schoharie Schoharie 1.50"
Fulton Schoharie 1.30" Huntersland Schoharie 1.50"
           
Whiteport Ulster 2.29" Esopus Ulster 1.55"
Saugerties Ulster 1.66" Kerhonkson Ulster 1.50"
West Shokan Ulster 3.90" Phoenicia Ulster 6.90"
           
Warrensburg Warren 1.50" (6:28pm) Lake Luzerne Warren 3.00"
Brant Lake Warren 2.00" (4:44pm) Queensbury Warren 1.69" (4:07pm)
           
Salem Washington 1.09" (5:46pm) Granville Washington 1.50" (5:05pm)
Cossayuna Washington 1.30"      
           
Woodford, VT Bennington 2.24" (7:00pm) Danby, VT Rutland 2.31" (5:57pm)
West Rutland, VT Rutland 1.10" (4:58pm)