HMS Grindall and HMS Hoste - D-day weather ships

I've previously initiated two threads on "D-day meteorology" ( and " HMS Grindall" (, both of which were seeking advice about two ships that were deployed on weather reporting duties in the East Atlantic during the D-day episode.

Unfortunately no-one was able to provide exactly the detail I needed, but having recently visited the National Archives I thought the following description on one of the Royal Navy's unsung roles during WW2 might be of interest.

The background of the story is the almost complete lack of weather observations between the UK and about 30W, and 30N to 60N, that were so vital to forecasters for all aspects of the war. Charts encompassing this area were plotted eight times a day, but at most just 12 observations were received - on average just over one observation a chart. It was the need to plug this large dataless area, and the approach of D-day, that saw the conception of "Operation CZ"

Operation "CZ" was instigated on 14 April 1944 ordering two frigates, HMS Hoste and HMS Grindall, to embark a Meteorological Officer and two meteorological ratings, before sailing from Londonderry on 21 April. The ships were to assume weather reporting duties within areas bounded by 47N to 57N, and 25W to 35W (Hoste) and 40N to 47N and 17W to 25W (Grindall).

Weather observations were initially required every six hours (00, 06, 12 and 18 GMT), in other words messages were being broadcast every six hours which made it relatively easy for the Germans to fix the ships' positions by DF.

Both ships remained at sea to cover operations "Tiger" and "Fabius" (the test landings on Slapton Sands), before returning to Londonderry about 4 May.

The follow-up operation, Operation CZII, was promulgated on 15 May; this ordered Hoste to a patrol area bounded by 52N to 59N and 20W to 25W, and Grindall to an area bounded by 42N to 49N and 20W to 25W. A third frigate, HMS Inman, was to act as a reserve, patrolling between 49N and 52N, and 20W to 25W.

The ships were ordered to be on station by 25 May, with Hoste and Grindall operating as before whilst Inman remained silent; once in their patrol areas they were to sail at economical speed to the maximum limit of endurance and, unless otherwise ordered, were to avoid contact with all other vessels. (ADM1/16313)

(Although the operation order required observations every 6 hours, the plotted meteorological charts show they were actually reporting every three hours.)

In the event Grindall was recalled to base on 14 June where, after a brief respite she joined 5th Escort Group. However, Hoste remained at sea for 37 days until 28 June, although this included a brief return to Londonderry early in the voyage to land two ratings who had been seriously injured by boarding seas.

By frequently breaking radio silence Hoste was in constant danger throughout her long period at sea, and in recognition of her contribution to the success of the D-day landings she was awarded the Battle Honour for Normandy, 6th June 1944. (ADM217/501)

HMCS Port Arthur assumed Hoste's role after she returned to Londonderry.

Not an 'exciting' tale but, as was written in another file, the weather reporting role was a soul-destroying occupation for a normal ship's company, and one that was not without its constant danger. Henry Curry, the Met Officer on the Grindall, remembers German radio broadcasts claiming that the ship's message had been intercepted and her position was known.

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