...
| Show If | ||
|---|---|---|
| ||
Discussed in the following Daily reports: |
Picture
1. Impact
The cyclone Stella passed the U.S east-coast on 14 March, bringing snow, sleet, freezing rain and rain on different part of the region. In front of the cyclone, a large parts of the activities in Washington D.C and New York City closed in preparation to large amount of snow. In the end most of the precipitation fell as rain in Washington (but with some freezing rain) and much less snow that expected in NYC. However, parts of upstate New York got more than 25in (~1 metre) snow.
2. Description of the event
3. Predictability
The plot below shows the accumulated snowfall from NOAA over 48 hours. During the event Central Park in NYC got 20 cm. Other snow total can be found here: snowtotals.txt
3.1 Data assimilation
The plot below shows the vertical sounding from Long Island measured 14 March 12z below, with the first guess and analysis included. The is an inversion in the profile around 1 km height that brings the temperature above the freezing point. With the cooler layer below it would have given favourable conditions for ice pellets.
3.2 HRES
The plots below show 24-hour accumulated precipitation for 14 March and the MSLP valid 12z the same day from HRES with different initial times.
3.3 ENS
The plots below show EFI and SOT for precipitation for 14 March.
...
The plot below shows the evolution of 24-hour precipitation forecasts for New York City for ENS (box-and-whisker) and HRES (red dot) and the model climate (red box-and-whisker).
The plots below show the probability of different precipitation types for Washington from 12 March 00z (left) and NYC from 13 march 00z (right). The plot for Washington shows a risk for freezing rain while the plot for NYC shows the risk for ice pellets.
The plot below show the cyclone feature product for maximum snowfall.
3.4 Monthly forecasts
3.5 Comparison with other centres
...
5. Good and bad aspects of the forecasts for the event
- The forecast predicted the existence of cyclone well from 9-10 March and onwards
- HRES forecasts before 11 March missed the northerly extent of the precipitation
- Overprediction of snowfall also in the last forecasts