The Driest Air Of The Nation Is Over The Inland Pacific Northwest

People mean value well-nigh the Pacific Northwest every bit beingness a moist place, precisely during mid-summer nosotros are ofttimes 1 of the driest.

An splendid mensurate of the amount of H2O vapor inwards the air is the dew betoken temperature, the temperature to which the air must live on cooled at constant pressure level to popular off saturated.  The higher the dew point, the to a greater extent than wet air contains. 

Here is a map of dew betoken at ix AM this morning.  The lowest dew points inwards the acre was inwards the Pacific Northwest due east of the Cascade crest (around 40F).  Middle of the terra firma together with inwards Florida?  Around 70F--very sticky.


Another mensurate of humidity is relative humidity, a mensurate of wet that likewise involves temperature.  Relative humidity tells us how much wet is inwards the air compared to the maximum it tin "hold".   Since warm air tin concord to a greater extent than H2O vapor than cool air, relative humidity tends to driblet every bit temperatures rise.  

Here is the relative humidity at the same fourth dimension every bit the inwards a higher house figure (9 AM Saturday).  The lowest relative humidities were over the  inland Northwest (both lilliputian H2O vapor inwards the air together with high temperatures) together with over the interior of California together with eastern Texas (very high temperatures).


Relative humidity varies greatly over the day, declining substantially during daytime every bit temperatures rise.    Let me illustrate this for today (Saturday) using forecasts from the UW WRF model. 

At v AM, when temperatures were relatively cool, the driest air is over the lower elevations due east of the Cascade crest (brown colors), amongst higher humidity along the coast.

Big changes past times xi AM, every bit warming causes a huge reject of relative humidity over most of the region.

And past times v PM, nigh the fourth dimension of max temperatures, the percentage was pretty much desiccated--with relative humidities below 30% inwards most locations away from the immediate coast.   No wonder your oral fissure felt parched together with you lot grabbed a cool drink.

10 PM tonight?  Cooling temperatures resulted inwards an growth of relative humidities.


In contrast, dew betoken hardly changed during the day.  To demo this, hither are the dew points for v AM together with v PM today.  Pretty similar. With drier air (dew points less than 40F) over much of the the high terrain together with regions due east of the Cascade crest--see below.



So when outsiders tease you lot well-nigh Northwesterners having webbed feet together with other jokes of our percentage ever beingness wet, experience gratis to right them, noting our wonderfully dry out weather during our nigh perfect summers.

Comments

Popular Posts