Hurricane/Tropical Storm Irene
(Click on images to enlarge)
While it had been an active tropical season, it was
not until we reached our ninth tropical system that one became a hurricane.
That storm was Irene, which had been a well defined tropical wave and formed
Irene actually weakened a notch as it tracked toward
North Carolina, making its first
However, even after tracking over land for 80 miles,
the storm maintained Category 1 hurricane strength, as it moved into the mouth
Heavy bands of rain showers well ahead of the main
storm began falling in our southern zones early Saturday morning. Radar
estimates and ground truth surface observations indicated up to two inches fell
These showers were slightly detached from the rain bands directly from Irene, but would likely NOT be considered a "PRE" due to the proximity being too close to Irene and these showers eventually merged with the outer rain bands of Irene Saturday evening (Aug 27). Also, the showers only produced localized higher amounts of around two inches, but most areas received less than an inch.
The rain shield directly assoicated with Irene overspread the region Saturday evening from south to north. Rainfall rates quickly increased to between half an inch to as much as an inch per hour at times by Sunday morning. The wind increased out of the north, mainly in the immediate Capital District, sustained around 25 mph, but gusting over 50 mph by mid morning.
The gusty winds, coupled with fully leaved trees and very wet ground, began producing a plethora of power outages, first in our southern regions, but quickly spreading north to include most areas by . Flooding and flash flooding commenced quickly, and a historic event unfolded.
A secondary dry slot working from the southeast sector of the storm began to shut the heavy rainfall down during the afternoon. However, a drizzly rain, falling from ice free clouds, persisted well into the afternoon and in some cases the evening. While this additional rainfall did not add much to the damage, it hampered rescue events.
The north wind relaxed a little, with gusts down to
around 30 mph. However, as the storm pulled away into
However, the worst part of the storm was the
flooding. Total rainfall, which fell mainly in under a 24 hour period, ranged
from around 4 inches to well over a foot of rain! The heaviest rainfall was
generally across the higher terrain to the west of the
Many of our rivers and streams in our area rose
rapidly to major flooding, some with localities reaching flood of records.
There was unbelievable devastation to many towns on the Schoharie and Catskill
Creek. The Mohawk and Hudson flooded in all locations and brought significant
damage to many places near its path. In
Numerous Floods of Record were achieved from this historical event:
1. Gilboa Dam on the Schoharie Creek
2. Breakabeen on the Schoharie Creek
3. Burtonsville on the Schoharie Creek
4. Granville on the
5. Cold Brook (
6. Rosendale on the Rondout Creek
7. Canajoharie on the Canajoharie Creek
9. Rockingham on the
11. Saxtons on the
12. Prattsville on Schoharie Creek (gage destroyed...likely a record...will get flow estimate from USGS)
The same issues and concerns from the Spring 2011
floods arose once again with our River Forecast Points at several locations
where automated gages do not exist. The only difference was that this time we
received bad readings from the staff at several of these points. On Monday,
August 29, 2011 at approximately 1100 UTC Lock 5 (SYLN6) gave us a reading of
90.2', when checking with the person the next day they apologized and told us
the reading at that time should have been 95.1' (we had forecast 96', the
difference between the correct reading and the inaccurate reading was 27000 cfs
and two flood stage categories Major versus Minor). As bad as this data was,
the data from MCVN6 was even worse. On
Top 5 Wettest Calendar Days at
***It should also be noted this storm for a 24-hr moving time period may have the 2nd greatest rainfall behind Floyds 6.0" from 16-17 SEP 1999.
Top Ten Storms with the Greatest Precipitation
4. 5.76" August 27-29, 1927 Heavy thunderstorms;
Low Pressure moving up the
5. 5.46" June 27-30, 1973 Showers and thunderstorms with a slow moving cold front
6. 4.96" August 31 - September 1950 Showers and thunderstorms; Moist air mass from TS over Southeast
10. 4.76" October 8-9, 1903 Slow moving coastal low pressure system
Above: Hurricane model tracks initialized at 12Z 23 August (left), 00Z 24 August (middle) and 12Z 27 August (right). Note the spread in all the forecast model tracks and how there was a noticeable shift in the forecasted tracks from 23 August to 24 August. There was still notable spread in the model solutions on 27 August.
Above: GFSEnsemble member predicted tracks for Irene, initialized 12Z 23 August. Note these forecasts were similar to all the model forecasts initialized at 12Z 23 August.
Above: Hurricane model intensity forecasts. Notice the consensus that the hurricane intensity was predicted to decrease, but the large spread contributed to high uncertainty in the magnitude of the decrease in intensity.
Above: GFSEnsemble probability for 4 inches in 48 hours initialized 12Z 23 August (left), and 00Z 27 August (right).
Above: Soundings from 12Z 28 August for Albany, NY (left), Chatham, MA (center left), Portland, ME (center right), and 00Z 28 August from Upton, NY (far right). Note the strong veering wind profiles and deep moisture.
precipitation estimated from the
Above: Hydrographs from river gages across eastern NY and western New England, showing moderate to major flooding at most river points.
Above: Photos of flood damage from Prattsville and surrounding areas of Schoharie County, through Windham and surrounding areas of Greene County.