Page History

...

Note: HRES and Ensemble Control Forecast (ex-HRES) are scientifically, structurally and computationally identical.  With effect from Cy49r1, Ensemble Control Forecast (ex-HRES) 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.

Example of freezing rain, Canada

Freezing rain is a very hazardous type of precipitation which brings a significant risk to aviation, transport, communication and indeed to life.  There are outputs to highlight the probability and amounts of freezing rain.  An indication of freezing precipitation gives no information on likely accumulation of glazed ice although there must be a serious risk.  Heavier precipitation rates suggest a potential for greater accumulation.

...

Fig:8.1.10-20: Surface analysis from Met Office VT12UTC 08 January 2024.  The area of freezing rain is shown as an upper warm front.

Example of freezing rain, France

An intensifying slow-moving frontal zone was slow-moving across northern France and southern Germany.  The front separated very cold air to the north from warm moist air to the south.  Precipitation type histograms from a series of ensemble forecasts consistently identified the risk of freezing rain.  The structure of the forecast atmosphere at the intersection of the air masses is typified by the vertical profile at Paris. Ice pellets were forecast at Bonn on the northern flank of the freezing rain where the temperature in the warm air only just exceeded zero deg C.  

...

Fig:8.1.10-21: Precipitation type histograms for Paris from a series of ensemble forecasts.  Note: At the time of the diagram the resolution of the medium range ensemble was 18km.

Image Modified

Fig:8.1.10-22: Precipitation type histograms for Paris from a series of ensemble forecasts.  Note: At the time of the diagram the resolution of the medium range ensemble was 18km.

...

Note: HRES and Ensemble Control Forecast (ex-HRES) are scientifically, structurally and computationally identical.  With effect from Cy49r1, Ensemble Control Forecast (ex-HRES) 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.

Example of freezing drizzle, SE England

Freezing drizzle can be as much of a hazard as freezing rain.  The "Probability of Freezing Rain" option on ecCharts can show 0% when the default threshold is used.  Freezing drizzle can be seen if a very low threshold (say >0.01mm in previous 6hr) is applied.

...

Note: HRES and Ensemble Control Forecast (ex-HRES) are scientifically, structurally and computationally identical.  With effect from Cy49r1, Ensemble Control Forecast (ex-HRES) 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.

(FUG Associated with Cy49r1)