Relative humidity
2006-10-09 17:38:40.000 – Ryan Knapp, Meteorologist
NULL
The summit has, in effect, been a desert for the past three days. With strong subsidence beneath a massive ridge of high pressure the air was compressed and warmed. There was no feed of moisture from any direction as winds were nearly calm through a considerable portion of the lower atmosphere. The result was progressively lowering relative humidity values which bottomed out last night at 1.4%.
Let me say that again, 1.4%.
That is extreme.
What is even more impressive, between the 4 am and 5 am observations, subsidence ended which allowed the temperature to go from 48.5 degrees Fahrenheit with humidity of 4.2% down to 41.3 degrees Fahrenheit with humidity of 83%. When I was forecasting this morning, I did not expect us to moisten up as quickly as it did. I was expecting it to gradually rise through the day not shoot up in one hour. But this example illustrates how rapidly the weather can change on the summit and to remind visitors to always be prepared for rapidly changing conditions.
Ryan Knapp, Meteorologist
From One Mountain to the Next
From One Mountain to the Next By Ellie Derry Hi everyone! My name is Ellie Derry and I am one of the fall 2026 interns at the Observatory. I’m super excited to be here
Mountains and Meteorology: What More Could a Girl Need?
Mountains and Meteorology: What More Could a Girl Need? By Emily Grainger Hi everyone! My name is Emily Grainger, and I am one of this fall’s Summit Interns atop Mount Washington! I’m from Orlando,
My Fear of Weather Became a Love of Meteorology
My Fear of Weather Became a Love of Meteorology By Kaitlin Farrell Hello! My name is Kaitlin Farrell. I am one of the fall summit interns here at Mount Washington Observatory. I recently graduated
