Atmosphere 2022, 13, 1634 
110f 21 
10° W 0° 210°E 20°E 
655° N 
50° N 
55° N 
50° N 
45° N 
10° W 
0° 
7 
ws a 
10° FE 20° E 
m 
N 
65° N 
60° N 
55° N 
50° N 
45° N 
#20 
N - 
a 
zz 
0 = 
E 
—10 < 
—20 
Figure 8. See Figure 7, but for days with SE weather type derived from 1950-2019 ERA5 reanalysis. 
3.4.2. Weather Types 
Figure 9 shows the relative frequencies of the LWT (Section 2.2.2) calculated from daily 
ERA5 SLP data over the entire period (1950-2019) independent of the occurrence of ELWs 
(left), as well as for the 24 h before the ELW (right). 
Cuxhaven (271 events below 0.55th percentile) 
Climatology 
24h before negative storm surge 
14 > 
756% 
5.6 % 
L 0 
9.7 
% 
86.3 % 
I 
1,8% 
0.7 % 
56% 
14% 
Bag % 
10.5 % 
Figure 9. Left: Mean distribution of LW'Ts determined from daily means of ERA5 sea-level pressure 
for the entire period from 1950 to 2019. Right: Mean distribution of LWTs 24 h before ELW at 
Cuxhaven (Tnw below 0.55th percentile of all Tnw) between 1950 and 2019. 
While a south-east weather type (SE) occurs climatologically with a probability of 
.0.5%, it occurs with a probability of 86.3% directly before an ELW. Therefore, an SE LWT is 
8 times more likely at the onset of such an event. This difference is statistically highly signif- 
icant (p < 0.001; tested via 10,000-fold bootstrapping). For the other LWTs, this probability 
decreases proportionally: LWTs with northerly winds (NW, NE) are hardly found (0 and 
0.7 %, respectively) preceding ELWs. This finding confirms our geoscientific expectation 
since south-easterly winds can be regarded as offshore for the area around Cuxhaven. 
3.4.3. Gale Strength 
Similar to Figure 9, Figure 10 shows the distributions of gale strength derived from the 
LAMB weather classification based on daily ERA5 data over the entire period 1950-2019 
(left), as well as for the 24 h before the ELW (right).