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Fig8.1.16.3-7:  Strike probabilities for NORU up to 12UTC 8 August 2017 (T+240) based on ensemble and HRES forecast, data time 12UTC 30 July 2017. Note: HRES and Ensemble Control  are scientifically, structurally and computationally identical.  With effect from Cy49r1, Ensemble Control output is equivalent to HRES output shown in the diagrams.   At the time of the diagrams, HRES had resolution of 9km and ensemble members had a resolution of 18km.

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Fig8.1.16.3-8: Strike probabilities for NORU up to 10 August 2017 (T+240) based on ensemble and HRES forecast, data time 12UTC 1 Aug 2017. Note: HRES and Ensemble Control  are scientifically, structurally and computationally identical.  With effect from Cy49r1, Ensemble Control output is equivalent to HRES output shown in the diagrams.   At the time of the diagrams, HRES had resolution of 9km and ensemble members had a resolution of 18km.

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A limit is placed on the roughness length scale parameter in order to avoid the effect of too much drag from the sea surface in the lower atmosphere and enable more realistic (stronger) winds to be forecast in the vicinity of relatively intense tropical cyclones.  It should also be noted that tropical cyclone development with strengthened winds has only a limited effect upon the size and character of waves developed by the Wave model.  The model change to limit the roughness length scale at very high speeds was introduced in cycle 47r1 in June 2020.   See Section on Waves near tropical storms.

RSMC official forecasts of tropical cyclones take precedence

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