Status:Ongoing analysis Material from: Linus, Fernando
1. Impact
On 5 August TC Debby made landfall on north-western Florida. The system moved to the north-east and entered the Atlantic again before making a second landfall. The system brought extreme rainfall along its path.
2. Description of the event
The evaluation of the rainfall will focus on 72-hour rainfall on 5 August 00UTC - 8 August 00UTC in a 0.5x0.5 box centred on Savannah (32.1N, 81.2W).
The plots below show analyses of MSLP and 6 hour rainfall from 3 August 00UTC to 8 August 00UTC, every 12th hour.
3. Predictability
3.1 Data assimilation
3.2 HRES
The plots below show 72-hour precipitation in observations (first plot) concatenated 9km short forecasts (second plot) and NEXRAD radar accumulation (third plot).
The plots below show ENS control forecasts with different lead times.
The plots below show forecasts from DestinE.
The plots below show forecasts from AIFS.
3.3 ENS
The plots below shows EFI and SOT for 3-day precipitation from different initial dates.
The plot below shows the forecast evolution plot for 72-hour precipitation for the box outlined in the plots above.
Observations - green hourglass
Analysis - green dot
ENS control–red
DestinE4.4km - purple dot
AIFS - cyan dot
ENS - blue box-and-whisker
ENS 49r1 - pink box-and-whisker
Model climate (48r1) – cyan box-and-whisker (To be added)
Ensemble mean as black diamonds. Triangle marks the maximum in the model climate based on 1800 forecasts.
The plots below show the tropical cyclone track for TC Debby for the operational ECMWF forecasts from 5 August 00UTC (first plot) to 26 july 00UTC (last plot). The symbols shows the position on 5 August 00UTC (hourglass for BestTrack). HRES (red), ENS CF (blue), ENS PF (grey) and BestTrack (black). AIFS is included in green.
The plots below are the same as above but with DestinE in purple. Note that DestinE only run to 5 days ahead. However, the feature (at least in the tracks) seems to be missing in DestinE. But it could be a tracker issues as well.
The plots below show the same as above but of 49r1 e-suite.
The plots below show the tropical cyclone intensity (central pressure - top, maximum wind -bottom) for TC Beryl for the operational ECMWF forecasts from 5 August 00UTC (first plot) to 3 August 00UTC (last plot). HRES (red), ENS CF (blue), ENS PF (grey) and BestTrack (black). AIFS is included in green.
The plots below show the same as above but including DestinE.
The plots below show the same as above but of 49r1 e-suite.
3.4 Monthly forecasts
3.5 Comparison with other centres
4. Experience from general performance/other cases
5. Good and bad aspects of the forecasts for the event
- The track forecast flipped from the Atlantic to the Gulf of Mexico between 31 July and 1 August. The change somewhat better handled in the 49r1 e-suite.
- To weak intensification in o-suite while some members in the e-suite overdid the intensification before the landfall on Florida. Such member also produced very extreme rainfall for Savannah (700 mm)