Why the Pacific has the lowest pressures?

[arkestra]

The question is in the title. Is there any way to "normalze" pressures between basins?

[Aslkahuna]

The pressures are lower because the ambient pressure in the Pacific are lower. Pressures are reduced to SLP worldwide based upon observed values for ease of analysis. "Normalizing" pressures by applying a fudge factor may be satisfying to egos but not very scientific as it ignores the true nature of what happens globally. Additionally, what sort of factor would one apply? as it would vary from year to year and most definitely from month to month. It is incorrect to say that ALL WPAC storms have lower pressures for a given intensity than ATL storms since studies of STY Paka showed differently and it is now recognized that late season storms, when ambient pressures in WPAC are higher, may have the same wind/pressure relationship as ATL storms. This has personal meaning as I went through TY Irma at Clark in 1974. Given the intensity of the storm there we felt that the 95 kt landfall intensity from JTWC was low. Irma was a very late November storm and 18 hours prior to landfall had a pressure of 939 mb after an ERC based upon the Paka study, Irma was probably very near STY intensity and made landfall more likely with 105-120kt. Based upon Clark's observed winds (which tend to be low because of terrain effects) JTWC carried Irma at 70kt when closest to us. PAGASA said 160 km/hr which is 85 kt. Based upon the amount of damage around and especially off base the Category 2 intensity seems more likely at that point-this requires a Cat 4 landfall given the nature of the terrain in the landfall area and time spent over land getting to the position just south of Clark.

Steve