...From The Weather Gage: The Aerology 50-Series

Richard H. Bouchard

The Metaphor

Closing with an enemy ship, an enterprising English captain had his crew throw lime into the air to blind his adversaries.(1) In the days of sailing ships, the wind was not only a safety concern, but a tactical consideration. A fundamental tactical objective of naval warfare was to seek the weather gage - taking a position upwind from the enemy in order to sail down the wind and have the advantage of maneuver. The term weather gage passed into general use as a metaphor for having the advantage.

With the demise of sailing ships and the ascendance of steam, the weather gage become less of a necessary tactical consideration until the arrival of naval aviation. With aviation, a new weather gage arose - the wind ruled again(2). Carriers led the United States to victory across the Pacific in World War II by using the new weather gage by turning into the wind to launch their aircraft.

Perhaps as a result of the technical revolution wrought by World War II and the optimism in the post-war years, weather came to be considered less of an exploitable tool and more of an obstacle to be overcome by engineering(3), as the "Holy Grail" of all-weather capability was eagerly sought. The idea of weather providing an advantage continued in the Army's doctrine and seeped into Joint Doctrine where:

Weather, mapping, charting, geodesy, oceanography, and terrain analysis are all areas where the joint force should achieve significant advantages.(4)

Taking its cue from Joint Doctrine, the Navy resurrected the weather gage metaphor(5) (albeit without the depth and pervasiveness found in Army doctrine(6) in its doctrine. But is it sufficient to simply pick-up the metaphor from here and move forward? The Navy, the originator of the weather gage concept, already has a series of "guide-books" in the now yellowing pages of the World War Two Aerology 50-series. They were promulgated by the Deputy Chief of Naval Operations (Air) who

..hoped that these studies will afford a clear view of the use of weather information during the planning, strategical, and tactical phases of the operation, and that they will form a basis for the better understanding of the application of weather information in future operations.

The primary objective of these analyses is to assist those officers who are charged with the responsibility for the planning and execution of similar operations.

Some of the reports where written by an operational commander and issued under the DCNO(Air) Aerology cover. They were divided into four areas: Amphibious Warfare, Naval Warfare, Naval Operations, and Tropical Cyclones(7). Highlights of the publications, less the Tropical Cyclones, follows:

Aerology And Amphibious Warfare

NAVAER 50-30T-1, The Invasion of Sicily (Promulgated Jan 1944): The best of the series because it demonstrates the importance of forecasts tailored to local conditions. It succinctly provides the strategic and tactical requirements for the simultaneous amphibious and airborne assaults, a climatological analysis, and target-specific considerations, especially surf conditions and land-sea effects. The climatological analysis indicated:

It is difficult to find a theater of operations in which weather conditions are more favorable for amphibious operation than in the Western Mediterranean during the summer. But any unforseen departure form the so called "normal" conditions could result in a serious handicap to our forces.

However, the aerologist (LCDR R. C. Steere) and the Commander, Naval Forces, Northwest African Waters prepared for the unlikely.(8) The American landing beaches lay along the southwest coast of Sicily generally exposed to northwesterly and southerly winds. Southerly winds would be strengthened by the afternoon on-shore land-breeze effect. On D-1, winds freshened out of the northwest peaking at 31 knots with gusts to 37 in the afternoon. Recognizing the weakening character of the approaching front with nightfall, LCDR Steere forecast northwesterly winds 10 to 15 knots. At H-hour, winds were generally out the northwest up to 16 knots depending on the orientation of the beaches. The D-1 weather had serious, but not critical effects causing sea sickness in embarked troops, making station keeping, and off loading difficult. On D-day the surf caused many landing craft to broach and disrupted the timing of the assaults, but in some cases the surf helped craft over outer bars.

Provided lessons learned:

In closing, the report reinforced the experience of the North African landings and quoted the headquarters of the Commander in Chief (Eisenhower): "The strategic and tactical importance of weather forecasts cannot be overemphasized."

NAVAER 50-30T-2, The Occupation of Kiska (Promulgated May 1944): Where the fog of war was more than metaphor. Fog frustrated bombing, shore bombardment, and reconnaissance of the island.(9). When the landing did occur, it revealed that the Japanese had evacuated the islands two weeks earlier. Observations were a key factor, such that an AG was assigned to a submarine to take weather observations.

NAVAER 50-30T-3, Operations of the Seventh Amphibious Force (Promulgated Aug 1944, may have been authored by LCDR Betts):Covers the period 30 June 1943 - 2 January 1944 and the landings on Woodlark and Kiriwana Islands, Lae, Finschafen, Arawe, Cape Gloucester, and Saidor. VII Amphibious Force, commanded by RADM Daniel Barbey, and the Army Engineer Brigade carried one-million troops and one-million tons of supplies as General McCarthur leap-frogged along the coast of New Guinea(10). Of significant importance was the weather reports by Aerographer's Mates aboard PT Boats in advance of the invasion force. Also several seemingly-impossible landings were achieved when modern weather analysis techniques were applied rather than relying on so-called local experts and their rules-of-thumb.

NAVAER 50-30T-4, The Occupation of the Gilbert Islands (Promulgated Oct 1944): More infamous for horrific casualties caused by the problem of getting over the surrounding reef, "Weather conditions throughout were unusually favorable." The equatorial front was displaced more northward for that time of year than usual restricting Japanese air operations from the Marshalls.

NAVAER 50-30T-5, The Occupation of the Marshall Islands (Promulgated Nov 1944):Operations in the Marshall islands occurred during January and February 1944. Pre-planning identifies that possibility that steady northeast trade winds might produce unfavorable seas and surf on the exposed beaches. In preparation for that eventuality Commander, Group Two, Fifth Amphibious Force devises an alternate plan to force the lagoon at Kwajelein. The landings are delayed a day and the alternate plan to force the lagoon is invoked. In conjunction with the landings at Eniwetok and to prevent the redistribution of forces, carrier air strikes are planned for the Japanese base at Truk. The American strike force deliberately uses a weather front to conceal itself from Japanese air patrols from Truk and the Mariana Islands (in contrast to the tactics 10 months earlier at the Battle of the Coral Sea).

NAVAER 50-30T-6, The Assault Landings on Leyte Island (Promulgated Dec 1944): Much of the report discusses considerations for typhoons. A near typhoon affected air support for some preliminary landings at the entrance of Leyte Gulf, but the landings proceeded. The winds associated with the near typhoon blew off the camouflage of Japanese installations revealing their positions to attacking aircraft. The "lack of weather was directly responsible for the success of the operation" culminating with the landing on Leyte and MaCarthur's return to the Philippines on 20 October 1944.

NAVAER 50-30T-8, The Invasion Of Southern France (Promulgated Jan 1945): D-Day is based upon the need for over-the-beach sustainment for 30 days after D-Day and the increasing frequency of strong mistrals in fall and winter. D-Day is set for 15 August 1944. D-Day weather is excellent - though the first "real" mistral on 2 September brings sustained winds of 50 knots with gusts to 60 knots. As part of the planning, a storm plan is established and a rear-echelon aerology unit serves as a back-up for the flagships's forecast and warnings responsibilities.

Aerology and Naval Warfare

NAVAER 50-1T-12, The Battle of the Coral Sea (Promulgated Apr 1944): Weather had a profound effect upon the outcome, as a frontal system oscillated within the battlespace frustrating both American and Japanese air scouting. The "weather scorecard" provides ringing indictment on the penalty for ignoring weather considerations - all the losses occurred outside of the frontal zone:

Favorable Weather Conditions for U.S. Forces:
Japanese American
Vessels Sunk 9 0
Vessels Damaged 1 0
Aircraft Lost 24 9

Favorable Weather Conditions for Japanese Forces:
Japanese American
Vessels Sunk 0 3 (Lexington, Neosha, Sims)(11)
Vessels Damaged 1 1
Aircraft Lost 51 57

None of the Japanese or American commanders knowingly adjusted tactics or search plans, or took advantage of the front(12).

NAVAER 50-40T-1, The Battle of Midway and The Bombing of Dutch Harbor (Promulgated Mar 1944): Pays respect to the skill of the Japanese aerologists in their strategic use of weather to conceal the approach of their forces to both Midway and Dutch Harbor. Apparently learning the lesson of Coral Sea, the American air patrols paid special attention to the fronts to probe both within and beyond the fronts. The fronts hampered any follow-up of the retreating and defeated Japanese Midway force. The report also describes an incident in the "misuse" of weather. During the attack on Dutch Harbor, a Japanese carrier retreated into a fog bank to conceal itself from a possible follow-up American strike. The returning Japanese aircraft could not find the carrier and all aircraft were lost. However, review of several post-war histories do not relate this incident(13).

NAVAER 50-40T-2, Fleet Air Wing Four Strikes (Promulgated Jun 1945): In the same vein as VII Amphibious Force (NAVAER 50-30T-3), FAIRWING FOUR overcomes what local experts called impossible and conducted strikes and reconnaissance from Attu in the Aleutians against the Japanese base at Paramushiru in the extreme northern Kurile Islands (a 1240-mile round-trip). From December 1943 through May 1944 they conducted 41 strikes and lost only one aircraft to adverse weather conditions. Commodore Gehres (In March 1945, Gehres was CO of the USS Franklin when it was devastated by kamikazes and survived) pays tribute to the weather forecasters who inspired the aviators' confidence in their forecasts by accompanying the missions to verify their own forecasts.

NAVAER 50-40T-4, The First Raid on Japan (Promulgated Feb 1947): One of the most stirring wartime newsreels is of Doolittle's raiders lifting off from the deck of the carrier Hornet on 18 April 1942 in the middle of a storm-tossed sea. The launch time is dictated by possible detection by Japanese vessels. The en route and target forecasts called for clear skies over Japan and tail winds all the way as a frontal system moved past the Task Force the night before the launch. The weather en route and over the targets was as forecasted, but without adequate observations west and north of Japan a low developed over the East China Sea thus obscuring Chinese landing fields leading to the loss of nearly all the aircraft.

Aerology and Naval Operations

NAVAER 50-45T-1, Weather and Occupation of Northern Japan (Promulgated Mar 1946): An interesting note is that the Japanese surrender ceremonies aboard USS Missouri are delayed from 31 August to 2 September 1945 because of three typhoons in late August. Third Amphibious Force undertakes the monumental task of deploying and supplying the occupation forces during the peak of the typhoon season. Nine typhoons occur during September and October resulting in some delays due to diversion of ships, but only one side-carry pontoon and no lives are lost. The most powerful typhoon in the western Pacific occurs during the peak of Third Amphibious Force operations - some 363 ships at sea requiring 23 separate diversions(14).


Despite differing warfare areas and different parts of the globe, several common lessons appear throughout the Aerology 50-series. Thorough preparation is necessary, but one must not slavishly plan according to the "normal" conditions. Even as recently as Desert Storm, the climatology indicated a rather benign climate for operations in the South West Asia theater, but the weather turned out "worse than normal" and "became a major impediment to the conduct of the air war"(15). The operational commander must have plans in place to effectively deal with departures from the normal.

Weather information is critical to weather prediction and thus to operational success. Both observations and the requisite forecasts and warnings require rapid dissemination to be of the most use. As recently as Operation Restore Hope, weather satellite images were transported by helicopter from the amphibious assault ship off the coast of Somalia to the Commander of the Joint Task Force ashore because of the lack portable satellite receiving systems.

The on-scene Aerologist and Aerographer proved invaluable in the understanding of both the geophysical and tactical environment and in being able to respond to rapid changes in both. Being on-scene also can improve the weather service by inspiring confidence (as FAIRWING FOUR found) or possibly due to the instant feed-back. Instant user feed-back has been (arguably) suggested as a contributing factor in recent statistical superiority of some types of forecasts by m ilitary forecasters versus similar forecasts by national civilian. forecasters.(16) That instant feedback would be lost should weather support become a "virtual organization" in the quest to reduce future shipboard manning requirements (17) (18)

The publications of the Aerology 50-series, though over 50 years old, still enlighten and contain fundamental lessons that apply to the naval operations of today and tomorrow. It would be easy to dismiss those lessons with today's high-tech arsenals. In fact in an age of diminishing resources, but increasing technical capabilities and changes in the employment of naval forces, it may be time to reconstruct the Aerology-50 series for recent naval operations.

1. Archer Jones, The Art of War in the Western World, University of Illinois Press, 1987, p. 210.

2. William C. Chambliss, Wind Rules Again, United States Naval Institute Proceedings, Vol. 69(5), 1943, pp. 636-638.

3. The now-defunct Naval Warfare Publication 1, Revision I, discussed the environment in passing as something to be overcome rather than exploited. See paragraphs, Logistics Independence;, Maritime Patrol Aircraft;, Surveillance Systems; and indirectly in, Defensive Strength.

4. Joint Publication 1, Joint Warfare of the US Armed Force, (Washington, DC: National Defense University Press, 1991), p. 57.

5. Naval Doctrine Publication 1, Naval Warfare, (Washington, DC: Department of the Navy, 1994), p. 61.

6. Field Manual 100-5, Operations, (Washington, DC: Department of the Army, 1993), pp. Index-6 and Index-10.

7. The Tropical Cyclone reports are: NAVAER 50-45T-8, Operational Analysis -- Typhoon Warning System; NAVAER 50-1T-29, Operational Aspects of Hurricane Warning Services (Atlantic); NAVAER 50-1T-37, Tropical Cyclones.

8. LCDR Steere was highly praised by Admiral Hewitt for his North African forecasts when he applied detailed analysis and on-scene conditions to provide the critical Go forecast for the invasion despite the No-go forecasts from London and Washington. D-day was the last day for the next 60 days suitable for amphibious landings. See: H. Kent Hewitt, The Landings in Morocco, November 1942, United States Naval Institute Proceedings, Vol. 78(11), pp. 1243 - 1253; and H. Kent Hewitt, Naval Aspects of the Sicilian Campaign, U.S. Naval Operations in the Northwestern-African Mediterranean Theater - March - August 1943, United States Naval Institute Proceedings, Vol. 79(7), pp. 705-723.

9. American forces at Dutch Harbor become aware of the probable Japanese occupation when weather observations from Attu and Kiska ceased on 8 and 9 June 1942. For a thorough treatment of the effect of weather in the Aleutian Operations see: C.A. Wilder, Weather as the Decisive Factor of the Aleutian Campaign, (FT. Leavenworth: Army Command and General Staff College, 1993).

10. Ronald H. Spector, Eagle Against the Sun, The Free Press, 1988, pp.178-182.

11. The report did not include Neosha and Sims as that table was organized by date, but both ships were in the clear zone when discovered and attacked.

12. Richard W. Bates, The Battle of the Coral Sea. May 1 to May 11 Inclusive, 1942. Strategical and Tactical Analysis, (Newport, RI: Naval War College, 1947), p. 116.

13. These include:

  1. Samuel Eliot Morrison, History of U.S. Naval Operations In World War II, ( New York, NY: Little, Brown and Company, 1953), Vol. 4, pp. 160-184.
  2. Paul S. Dill, The Imperial Japanese Navy, (Annapolis, MD: Naval Institute Press, 1978), pp.168-171.
  3. Spector, pp.178-182

14. Compare to a recent count of all U.S. Navy ships - 362 on June 26, 1996. Navy Times, July 8, 1996, p. 32.

15. Eliot Cohen , Gulf War Air Power Survey, (Washington, DC: Department of the Air Force, 1993), Vol.I, p. 87.

16. C. S. Ramage, Forecasting in Meteorology, Bulletin of the American Meteorological Society, Vol. 74(10), 1993, pp. 1863-1871.

17. Scott C. Turner, Tomorrow's Fleet - Part I, United States Naval Institute Proceedings, Vol. 122(7), July 1996, p. 56.

18. Marvin E. Butcher, Jr., Time for Real Reform, United States Naval Institute Proceedings, Vol. 123(4), April 1997, p. 56, questions the need for restricted line officers which include Meteorology and Oceanography officers.