Post New Year’s Day 2010 Storm (Click on images for larger display)

 

This was an extremely complex event as very deep surface low developed in the western Atlantic Ocean on the evening of New Years Day, retrograded into the Gulf of Maine during the holiday weekend. The models leading up to this event were quite diverse with solutions as earlier in the week, global model consensus favored a deep surface low in the vicinity of Long Island/NYC. We began to highlight the uncertainty early Monday morning December 28th. Numerous discussions from NWS Offices across the region also hinted at the high variability and low confidence forecast heading into the holiday weekend. In fact, this uncertainty remained even during the event!

 

As we approached closer to the event, it seems the NAM was the better model with respect to terrain influences seen in its QPF field but its amounts were quite high. Several model runs showed QPF totals across the Green Mountains and portions of the Catskills in excess of 1" with global models in a courser resolution were at least half as much. Numerous collaborations with area NWS Offices were a huge part leading into the event. The national guidance from NCEP HPC leading into this event was also underrepresented as forecast values were considerably lower, but placement was quite well (that includes the lack of snow forecast over portions of the Adirondacks which did seem to verify). The reason for the lower snow totals were snow to liquid ratios that were generally in the 20-40:1 range for the majority of this event.

 

A few main points:

 

NAM output once again proved to be highly beneficial, including the wind and temperature forecast. Forecaster confidence is increasing with the NAM output and its associated MET guidance. The only downfall was a lack of BUFR files in locations where the heavier snow did fall.

 

Multiple headlines/hazards become quite a challenge as we had a combination of winter headlines along with wind advisory headlines. Blizzard Warnings were considered at one point. Speaking of Blizzard Warnings, there was plenty of collaboration with surrounding offices. However, in retrospect, no one would have verified based on the blizzard criteria as it is difficult to receive pure blizzard conditions in our CWA. During the heart (00Z 3 JAN to 00Z 4 JAN) of the event local METARS justified not having blizzard conditions with visibilities generally in the 3/4SM to 2SM range despite the blowing snow.

 

This was a multifaceted event which was synoptically driven but had many mesoscale features. Some of these features included areas of low level covergence, Lake Champlain enhanced snows across Washington, western Bennington and parts of Rensselaer and northern Berkshire counties, and upslope flow which was very pronounced across the higher terrain in Washington, Bennington and Windham counties at various times during the event as well as across the higher terrain south of the Mohawk River Sunday afternoon into Sunday evening.

 

It has been many years since we have had a Winter Storm that covered more than two days (it took three days worth of observations to construct the totals for this event Friday evening through Sunday evening), the last event which lasted for a duration longer than 48 hours was the December 11-14, 1992 Winter Storm.

 

Strong gradient winds also occurred during this Winter Storm. Gore Mountain in northwest Warren County was closed on Sunday, January 3, 2010 as they were not able to run their lifts or the gondola due to sustained winds of 40-50 mph and gusts 55-65 mph. Some measured peak wind gusts during the event included: 51 MPH at KALB at 1146 PM on 1/2/2010, 51 MPH at New Salem at 427 PM on 1/2/2010, and 50 MPH at KPSF at 113 AM on 1/3/2010.

 

The snow ratios were difficult to resolve from this storm and the amount of blowing and drifting snowfall was difficult to get near accurate measurements. It is bothersome how poorly the ASOS gages recorded liquid equivalents. For example, KDDH did not have the strong winds like KALB...but measured a mere 0.26 of liquid equivalent on 1-4 JAN !!! There were reports of 16-20 inches of snowfall ! This would imply 80-100:1 snow to liquid ratios !

 

The impact of the bent back warm front and the snow totals on the afternoon of 4 JAN in for the northern and eastern Catskills were intriguing. The guidance yielded 1-2 tenths of an inch of snowfall. Most of these locations received a coating to a few inches prior to this burst of snow. None of the guidance caught this effect.

 

Four-panel displays

 

  

 

Left:  500 hPa heights and vorticity from the GFS, NAM, GGEM and ECMWF

Middle:  MSLP mean and spread, SREF MSLP, Prob12 of 0.60” liquid equivalent and SREF prob12 >4” snow

Right:  MSLP from the GFS, NAM, GGEM and ECMWF

 

Note the consistency between the guidance sources, especially predicting the retrogression of the surface and upper features.

 

Anomalies

 

 

 

500 hPa heights spread, mean and anomalies for GEFS (left) and SREF (right)

 

Note the strength of the upper system that was predicted, between -3 SD and -4.5 SD from normal.

 

 

 

MSLP spread, mean and anomalies for GEFS (left) and SREF (right)

 

Note the strength of the surface low pressure center, between -3.5 SD and -4.5 SD from normal.

 

 

 

 

850 hPa winds and anomalies for GEFS (left) and SREF (right)

 

Note the strong U wind anomalies at -4 SD to -6 SD from normal, implying extreme low level moisture advection and convergence.

 

   

 

250 hPa winds and anomalies from the NAM, GFS, GEFS and SREF

 

Note the strong U wind anomalies at -3 SD to -4 SD from normal, implying a system very much cut off from the steering flow, and a long duration event.

 

AWIPS D2D displays

 

 

 

Left:  Loop of 850-700 hPa winds, vertical motion (color image) and theta-e

Right:  Station plot at 2000 UTC 2 January

 

Note the boundary layer theta-e advection and vertical motion push west and southwest around the periphery of the system centered off Maine.  Also note the surface flow from the northwest off the Great Lakes, enhancing the moisture advection and upslope across west-facing higher terrain in NY and VT.

 

 

 

NAM precipitation forecast from the 18Z 01 January and 06Z 02 January initializations

 

Note the consistency in the locations of the predicted maximum snowfall, and the amounts were relatively consistent as well.  Also note the preference in areas of higher terrain, and the extreme gradients of snowfall amounts in short distances.

 

 

Snow totals for the 1-3 January 2010 time frame across the northeastern U.S.

 

Note the extreme snowfall totals in northern VT, along the southern VT border with NY, along coastal MA and ME, and smaller maxima in the Catskills of NY and Long Island.

 

Any comments, questions or suggestions, please mail to:Neil.Stuart@noaa.gov