National Weather Service United States Department of Commerce

Hurricane and Storm Surge Watches Issued for the Northern Gulf Coast for Strengthening Tropical Storm Isaias

Tropical Storm Isaias is forecast to track toward the central Gulf Coast while strengthening into a hurricane on Thursday. There is an increasing risk of damaging hurricane-force winds and life-threatening storm surge impacts along portions of the northern Gulf Coast Friday into Saturday. Isaias will bring heavy rainfall to the central Gulf Coast and much of the Southeast Friday into the weekend. Read More >

A Discussion on Water Vapor (Moisture)

QUESTION 3:

If the air temperature was 90 F with a relative humidity of 60 percent in the afternoon, would it feel more uncomfortable to a person than if it was 75 outside with a relative humidity of 100 percent in the morning?

ANSWER 3:

At 90 with a relative humidity of 60 percent, it would "feel" like 100 degrees outside; at 75 with a relative humidity of 100 percent, it would only "feel" like 80. Despite the much different relative humidity value, the absolute humidity or dewpoint would be about the SAME in both these cases (i.e., dewpoint of 75 degrees). This "feeling" that combines air temperature and moisture in the air is referred to as the "heat index." Please return to the text for further information.

Back to Discussion on Water Vapor