The 28 October 2008 Elevation Snowstorm

(Click on thumbnails for larger images)

 

A strong cold front moved across the region Monday, October 27th ushering in a cold airmass. In the meantime, energy in the upper levels of the atmosphere moved into and rotated through the deep upper level trough over the eastern United States initiating strong cyclogenesis off the mid atlantic coast Monday night. On Tuesday, October 28th the low strengthened as it headed northward crossing Long Island in the morning and western New England Tuesday afternoon and evening, before heading into Quebec Canada Tuesday night. The thermal profile was critical. It was cold enough for snow across the higher elevations of the Catskills early Tuesday morning. Basically rain was occurring below 1000 feet, with mainly snow above 2000 feet and a mix of rain and snow at elevations between 1000 to 2000 feet. As the low moved northward Tuesday colder air was drawn into the region from the southwest causing the rain to mix with and even change to snow down to the valley floor. Snowfall reports varied greatly across counties, especially to the west of the Hudson River. Across Albany County snowfall reports ranged from a trace in Albany up to 13 inches in Medusa. The highest totals reported were 20 inches in East Jewett Greene County and Slide Mountain Ulster County. In addition, generally one to two inches of rain was also reported with the storm.

 

Most of the long-range guidance sources, including the GFS, GFSEnsemble and ECMWF were suggesting a significant event 3-5 days prior to the storm. The GFS consistently suggested the storm would track too far east for a significant impact in central and eastern NY, while the GFSEnsemble showed a broad spectrum in the spread, which suggested that our region still had a threat for a significant event. The ECMWF was most consistent, tracking the storm the furthest west, and suggesting the storm would have a significant impact on our region.

 

 

Figure 1. GFS Ensemble forecasted 500 hPa heights. Click on image for loop of forecasted 500 hPa heights from successive 12Z model runs, valid Tuesday 28 October. Note the significant differences in the forecasts in terms of strength, amplitude and trough axis longitude in each run. There were timing differences in addition to feature placement issues in each run, adding to uncertainty.

 

 

Figure 2. ECMWF 500 hPa heights. Click on image for loop of forecasted 500 hPa heights from successive 12Z model runs, valid Tuesday 28 October. Note similar issues as the GFS Ensemble. However, the upper trough axis and upper low were consistently further west than the GFS Ensemble.

 

 

 

Figure 3. Station plots and surface analyses. Click on the image to loop the station plots and surface analyses from midday 28 October through the evening of 29 October. Note the surface low tracked north northwest through western New England into Canada. This is not a traditional track for snowstorms across the area, but higher elevations can receive snow from storms tracking in this fashion.

 

a) b)

c) d)

 

Figure 4. ECMWF 850 hPa temperature with MSLP overlay valid 12Z 28 October for a) 12Z 24 October run, b) 12Z 25 October run, c) 12Z 26 October run, and d) 12Z October run. Note the consistent forecast for a tight thermal gradient and the 850 hPa temperatures below freezing across western New England and all of New York.

 

 

Figure 5. 12Z 27 October GEFS 850 hPa temperatures forecast and anomalies (shaded). Note the cold air that is forecasted to surge into the southeastern U.S., at 4.5 SD to 5 SD below normal.

 

 

Figure 6. 12Z 27 October GEFS 500 heights and anomalies (shaded). Note the 500 hPa heights in the southeastern U.S. at >5 SD below normal. This was forecasted to be an exceptionally strong storm.

 

Figure 7. 12Z 27 October GEFS 250 U and V winds and anomalies (shaded). Note the 250hPa U winds in the northern New England and southeastern Canada at 2-3 SD below normal. This was forecasted to be a relatively slow system, nearly cut-off from the main westerly steering flow.

 

 

Figure 8. 12Z 27 October GEFS probabilities for 1 inch in 24 hours and the spread. Note the probabilities of >60% over central and eastern NY, where the precipitation was maximized.

 

 

 

Figure 9. 12Z 27 October GEFS MSLP anomalies (shaded). Note the MSLP in the northern New England and southeastern Canada at 3.5 SD to 4 SD below normal. This was forecasted to be a strong storm.

 

 

Figure 10. 12Z 27 October GEFS 850 U and V winds and anomalies (shaded). Note the 850 hPa U and V winds associated with the storm were not remarkable, only 2 SD to 3 SD from normal.

 

 

 

Figure 11. Plume diagrams from the 12Z 27 October GEFS for a) Albany, NY and b) Binghamton, NY. Note all members suggest rain changing to snow. Also note that the range of expected precipitation was generally between 1.2 and 2.5.

 

 

Figure 12. Plume diagrams from the 00Z 28 October GEFS for a) Albany, NY and b) Binghamton, NY. Note all members suggest rain changing to snow, but less rain and more snow than the previous run. Also note that the range of expected precipitation was generally between 1.2 and 2.0.

 

 

a) b) c)

 

Figure 13. Satellite imagery from 28 October, showing a) visible imagery with lightning overlay at 1315Z, b) visible imagery with lightning overlay at 1515Z, and c) water vapor imagery at 1315Z. Note the lightning in southern NY and northern NJ, along with the textured cloudiness, illustrating the convective elements to the cloud cover, very proximate to the area of snow in the Catskills. Also note the diffluence seen in the visible and water vapor imagery, along with the deep drying and subsidence associated with a strong upper jet segment off the mid-Atlantic coast.

 

 

Figure 14. Radar reflectivity from KOKX during the morning of 28 October. Note the high reflectivity line of convection south of Long Island tracking north. The evolution implies a possible gravity wave, supported by the wind and temperature fields in the overlayed station plot.

 

a) b)

 

Figure 15. MSAS MSLP and wind barbs from a) 07Z 28 October and b) 13Z 28 October. Note the rapid deepening of the surface low.

 

a) b) c)

 

Figure 15. Soundings from Albany, NY (KALB) at a) 00Z 28 October, b) 12Z 28 October, and c) 00Z 29 October. Note the freezing line in red in each sounding. Also note the low level temperature profiles cooling progressively with time, as the freezing level descended with time.

 

 

 

Above pictures taken at Thatcher Park, west of Albany NY, courtesy of Howard Altschule of Forensic Weather Consultants.

 

 

Above pictures of Hunter Mountain in the Catskills. (These pictures are already at there maximum size.)

 

 

Above 3 pictures taken at Jiminy Peak, Windham Mountain, and Willard Mountain. (These pictures are already at there maximum size.)

 

 

 

 

 

 

 

 

Above picture taken at Belleayre Mountain. (This picture is already at maximum size.)