Naval History and Heritage Command

[information not related to the typhoon deleted]

4. Principal events are set forth chronologically with all dates East Longitude and all times Zone Minus Nine (Item)

ENCLOSURE "C" to CTG 38.1 Secret letter
Serial 0080 dated 14 June 1945
AEROLOGICAL REPORT OF THE TYPHOON OF 1-7 JUNE 1945

During the early morning of 5 June Task Group 38.1 passed through the center of in intense although small typhoon then located near Latitude 22°55'N, Longitude 132°10'E. This storm was first reported on 1 June by Weather Central Guam as forming in the vicinity of 12°N - 135°E, moving on a west northwesterly trajectory at 12 knots. A steady southwesterly circulation had prevailed over the operating area during the latter part of May, the southwest monsoon having become well developed by that time. On 3 June the winds were observed to back from southwesterly to southeasterly, this being the first indication of a cyclonic circulation to the south of the ship. There follows a summary of the observed weather conditions from 3 June through 7 June at which time the storm had passed from the operating area.

3 June: The storm center during the early morning was located 360 miles east of Manila, moving to the north at 15 knots. A stagnant cold front, oriented northeast-southwest, lay to the northwest between the ship and Okinawa. The ship passed through this frontal zone at 0500I accompanied by a wind shift from the south southwest to the east at 8-12 knots. Intermittent light rain, showers and thunderstorms were observed during the afternoon which reduced the ceiling and visibility to zero at times. Flying conditions were average during the morning but became bad in the afternoon.

4 June: At dawn the typhoon, now deepening rapidly and recurving to the northeast, was centered 360 miles to the south southwest of the ship. Broken (7/10) altostratus above 20,000 feet with scattered (3.10) cumulus based at 2000 feet were observed throughout the morning. At 0950I this task group, on orders from ComTHIRDFleet, discontinued operations and steamed at 12 knots on course 110°(T) in company with T.G. 30.8 in order to avoid the storm center then located to the south. During the morning and early afternoon, scattered light showers fell from the cumulus clouds. Late in the afternoon the low clouds increased to broken to overcast (8/10) and a light intermittent rain began to fall. Visibility was 3-6 miles in the rain areas but was otherwise unrestricted. The surface wind was from the south southeast 15-20 knots with gusts to 30 knots increasing steadily. Flying conditions were good in the morning but became undesirable after 1500I.

5 June: At 0134I the Task Group on orders from ComTHIRDFleet changed course to 300°(T). The winds increased steadily from the southeast reaching a maximum of 80-100 knots with instantaneous gusts to 120 knots and the barometer fell precipitously reaching a minimum of 958.3 millibars on board Hornet at 0545I with the ship located near the edge of the eye of the storm. The rain increased from light continuous to moderate continuous with occasional very heavy showers. The visibility varied from 0-1 mile and the ceiling between 0-1000 feet. Shortly after 0600I, the winds dropped abruptly to 24 knots as the eye of the storm was penetrated and backed from the southeast through the north into the west. The seas were extremely heavy near the edge of the eye with long parallel swells of a short period and 50-60 feet from crest to trough moving out from the storm center. Within the eye, the seas moderated markedly becoming 20-25 feet from crest to trough and of a confused pyramidal nature. As the storm center was crossed, the rain ceased and the outline of the sun became visible through a misty stratiform overcast based at about 800 feet. The temperature rose from 75°F at the edge of the eye to 78°F in the center falling again to 76°F as the opposite side was entered. The Task Group crossed the typhoon from its right to left side, passing through the eye southeast of the center. Consequently the wind and sea conditions observed after passing the center were not as violent as those previously experienced. Winds of 55-60 knots from the West with little gustiness and overcast low clouds based at 500-1000 feet giving light continuous rain were observed as the group moved out of the storm's center. Conditions improved gradually and the winds had become West 5 knots by 1500I.

6 June: The typhoon having moved off to the Northeast at 20 knots was centered at 27°30'N - 137°30' E at dawn. Broken to overcast (8/10) altoform clouds above 20,000 feet and widely scattered (1/10) cumulus of fair weather based at 2000 feet were observed throughout the day. A drier air mass particularly aloft was observed over the area having been displaced from the North by the typhoon's passage. Ceiling and visibility were unlimited. The surface wind continued Westerly 10-15 knots. Flying conditions were good.

7 June: The typhoon continuing on to the Northeast had begun to fill and had developed a frontal system through the storm center during the previous 12 hours. Continued fair weather with sky conditions similar to those observed on 6 June prevailed throughout the day. The surface winds veered into the North Northwest 8-013 knots the typhoon having ceased to dominate the circulation. Flying conditions were good to excellent.

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A surface synoptic chart showing the typhoon's trajectory as reconstructed from map analyses and radar observations and the Task Group track, a sequence of surface observations taken for the period from 3-7 June, a collection of all pilot-balloon soundings taken during the above interval, and a reproduction of the true wind and barometric trace are annexed hereto.

At about 0245I on 5 June a series of diffuse, concentric, crescent-shaped images were first noted on the SM radar screen. Their outline was indistinct and varied with time but always retained a spiral or circular characteristic. A few minutes later it became apparent that this image (or series of images) was moving toward the Northeast and not in the direction of other shower areas on the screen at that time. These other showers were moving toward the North Northwest, that is with the wind which was then from the Southeast. At 0330I a more definite crescent-shaped image became visible at the Southwesterly edge of the screen -- this was presumed to be the storm center as was later demonstrated.

Several of the photographs of the SM radar screen taken at intervals during the ship's passage through the storm center together with a chart of the storm's track are annexed hereto. This trajectory was determined from the radar bearing and distance recorded at the time each exposure was made. Although considerable dispersion in the plotted positions will be noted, a rather definite average track can be drawn -- this average track shows the typhoon to have been moving to the Northeast (043.5°T) at 18 knots and accelerating. Due to the high brilliance necessary in exposing the pictures, a large area of "grass" around the ship will be seen in each photograph.

Now that radar observations of two different typhoons (the other being that of 18 December 1944) have been made at close range by the same observers on Hornet, a comparison of the two can be made. A drawing of the storm center of 18 December 1944 together with a drawing of the recent storm center (drawn to the same scale) are annexed so that the characteristics of both storms can be compared. The most marked difference is in the distribution of precipitation about the center. The earlier storm carrying the heaviest rain over the left read quadrant whereas the recent storm shows the greatest rainfall over the right front quadrant. Both storms are of approximately the same size in over-all dimensions, the greatest difference being that the eye of the recent storm is approximately three times as large as that of the preceding storm. Many of the suggestions made in the Hornet report of the December storm as to typhoon construction have been substantiated by the observations of this storm -- bands of relatively clear air (descending air) have been observed surrounding the central rain patterns of both storms. The distribution of precipitation is apparently dependent upon the past history and present state of each particular storm -- the earlier storm was traveling Northwestward and was decelerating whereas the recent one was traveling Northeastward and was accelerating -- both were apparently deepening at the time of observation.

The radar images of typhoons and other cyclonic tropical storms should be familiar to all radar operators -- they are distinct from other weather images and once seen can be identified almost at once. A useful criterion in this connection is that typhoon images in the Northern hemisphere will appear to be moving in a direction between 60 and 90 degrees to the right of the surface wind direction whereas most shower patterns will be moving with the wind or very near to it.

Note: Principal events are set forth chronologically with all dates East Longitude and all times Zone Minus Nine.

Extract from Task Group Thirty-Eight Point One report serial 0080 of 14 June 1945. Original held by Modern Military Branch, National Archives and Records Administration, College Park, MD.

10 April 2001

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