Status: Ongoing analysis Material from: Linus, Fernando
1. Impact
On 29 January north-eastern U.S was hit by a snowstorm. The accumulation in Boston reached 60 cm and New York 21 cm, both among the highest values in the record.
https://en.wikipedia.org/wiki/January_2022_North_American_blizzard
2. Description of the event
The plots below show analyses of z500 (contour) and T850 (shade) from 27 to 30 January, every 24 hour.
The plots below show analyses of MSLP and 6-hour forecasts of precipitation from 28 January 00UTC to 30 January 12UTC, every 12 hour.
3. Predictability
3.1 Data assimilation
3.2 HRES
The plots below show observations from SYNOP (first plot) and HRES forecasts of 24-hour precipitation valid 29 January 00UTC - 30 January 00UTC, from different initial dates. The hourglass marks Boston.
The plot below show precipitation accumulation from NEXRAD on 29 January and from HRES forecasts.
The plots below show accumulated snowfall on 29 January from www.nohrsc.noaa.gov/ (first plot) and HRES forecasts of snow depth valid 30 January 00UTC, from different initial dates. The hourglass marks Boston.
3.3 ENS
The plots below show EFI for 1-day snowfall 29-30 January, from different initial times.
The plots below show the forecast evolution plot for 24-hour precipitation on 29 January (left) and snow depth (right) on 30 January 00UTC in Boston. Observation - green, HRES –red, ENS blue box-and-whisker, Model climate – red box-and-whisker. Triangle marks the maximum in the model climate based on 1200 forecasts, The black square marks the ensemble/climate median and diamond ensemble/climate mean. 60 cm of snow fell in Boston on 29 January. (Boston was snow free on 29 January 00UTC).
The plots below show the same as above but for New York City. 21 cm of snow fell in Central Park on 29 January. (New York was snow free on 29 January 00UTC).
3.4 Monthly forecasts
3.5 Comparison with other centres
4. Experience from general performance/other cases
- See event in ECMWf Newsletter 143 https://www.ecmwf.int/file/28420/download?token=GXPCqQUT
- For snow accumulation see https://www.ecmwf.int/en/newsletter/170/news/heavy-snowfall-denmark-and-sweden-start-december
5. Good and bad aspects of the forecasts for the event
- A temporal narrowing of the high EFI band around day 2-3, leading to decrease in signal for Boston and New York City
- Apparent overestimation of precipitation
- Apparent underestimation of snow depth