What heat we have!

The last two observations from KNAK, 97/80 and 99/79, have been amazing! The heat index of 118F is probably closest to the highest I've personally experienced... while maximum temperatures in Death Valley in 2003 were higher (over 105F), the dry air made the apparent temperature much lower. This is impressive - and ohttp://www.blogger.com/img/blank.gifppressive. See the last 72 hr trend in temperature, dew point, and heat index for Annapolis KNAK.

*Note: Heat index and relative humidity equations were adapted from the Humidity Formula web site and are appended below.

HI = -42.379 + 2.04901523(Tf) + 10.14333127(RH) - 0.22475541(Tf)(RH) - 6.83783x10**(-3)*(Tf**(2)) - 5.481717x10**(-2)*(RH**(2)) + 1.22874x10**(-3)*(Tf**(2))*(RH) + 8.5282x10**(-4)*(Tf)*(RH**(2)) - 1.99x10**(-6)*(Tf**(2))*(RH**(2)), where

Tf = temperature in Fahrenheit
and RH = relative humidity, given by

E/Es*100, where

Es=6.11*10.0**(7.5*Tc/(237.7+Tc)), and
E=6.11*10.0**(7.5*Tdc/(237.7+Tdc)),

where Tc and Tdc are temperature and dew point temperature in degrees Celsius, respectively.