31 



tiire, however, was the extremes of weather exliibited in so short a 

 time. From mild showery weather to winter blizzards and biting 

 cold; from bright clear days to persistent fog. On April 7, two dis- 

 turbances combined directly over the area and developed into a violent 

 cyclone giving northerly gales with blizzard conditions on that day 

 and the 8th and 9th. April 10 brought strong southerly winds with 

 warm temperatures and showers in front of a disturbance of wide 

 extent moving north-northeastward along the eastern seaboard over 

 Newfoundland and finally Greenland. This deep vortex initiated a 

 major movement of polar air southward in its wake bringing a succes- 

 sion of polar continental air masses over the Grand Banks region 

 giving Ice Patrol fine clear weather on the 1 1th, 12th, and 13tli. Stag- 

 nant conditions beginning on April 14th caused dense radiation fog 

 everywhere in the area of cold water on that day and April 15 and 16. 

 These conditions were dissipated on the morning of the 17th by the 

 arrival of a fresh outbreak of polar air which brought strong and cold 

 northerly winds but caused bright clear weather. During the last 

 half of AprU the weather was seasonably warm and mild with much 

 less boisterous conditions. No storms of any marked intensity passed 

 over the area and no winds of gale force were experienced. The 

 quieter conditions and particularly the higher average temperature 

 are due in part, of course, to the advancing season but more directly 

 to the more southerly locale of the Patrol vessel, the entire patrol 

 being spent south of the Tail of the Banks. For tliis reason, also, the 

 percentage of fog experienced is not at all indicative of conditions on 

 the Banks or in the ice area generally, being considerably less. The 

 average temperature for the month was 40.6° F., and the percentage 

 of fog, visibility less than 2 miles, was 29.6 percent. (See figs. 18 

 to 22.) 



MAY 



The first half of May was colder than might be expected for the 

 time of year but with normal percentage of fog. Only one storm of 

 any marked intensity passed over the area and this on May 6, bringing 

 strong westerly winds that day. Tliis storm dissipated quicldy on 

 May 8 without moving off to the eastward and left behind it a large 

 area of generally low pressure extending from Nova Scotia east to 

 longitude 30° W., with no definite center. The weather in this area 

 was characterized by light variable winds and fog patches and con- 

 tinued until the morning of May 9 when the storm apparently regen- 

 erated with a center about 200 miles south southeast of Cape Race. 

 This center deepened rapidly and moved slowly eastward, bringing 

 the Ice Patrol area strong northwesterly winds on May 9th and 10th. 

 The weather during the next few days was controlled by a disturbance 

 of slight intensity which moved slowly northeastward from the Virginia 

 Capes, passing just south of the Grand Banks and dissipated to the 



