Current Weather   Data As of   21:15   on  5/9/08

Forecast Made By Vantage Pro Instrument   Based Only On Current Obs.  
 Mostly cloudy and cooler. Windy with possible wind shift to the W NW or N  
Current Weather Heated Precip.
Sensor
Precip.=15
No Precip.=0 		NOT Heated
Dew & Precip.   Wet=15   DRY=0		 Time Since
Last
Measurable
Precipitation 		Current Solar
Radiation and
Trend Past Hr.
Today's  Max.		 Annandale Temp.
Trend Past Hr.
Weather Icon 0  Now
0  Max
0:00  Time		 15  Now
15  Max
4:35  Time
0 Watts/M²
-8 Watts/M²
454 Watts/M²		 55.3 °F     -0.70 °F

Nat. Airport Temp.
   Click for Washington, District of Columbia Forecast
Comfort Level-
Cool		 Precipitation Rate-
0.000 inches		 Beaufort Scale-
  Light Air		  ** Est. Cloud Base-
949 FT
Heat Index  60.5 °F
Wind Chill  55.3 °F		 Precipitation Last Hour-
0.00  inches		 Current Wind Gust-
       3  MPH
Past Hr. 1.1 MPH		 Barometer-
29.73 inches
Past Hr. 0.018 inches
Dew point Temp.-
51.5 °F
Past Hr. -0.19 °F		 Today's Precipitation-
1.89 inches		 Today's High Wind Gust-
19 MPH At 16:24		 Today's Max. 1 Hour Change-
0.033 inches
Relative   Humidity-
87  %
Past Hr. 1.6 %		 24-Hour Precipitation-
2.54 inches		 Today's Ave. Wind Direct.-
171 Degrees    Now   S		 Barometer Trend-
Rising
 **Virtual Wx. Station uses the formula Cloud Base(Ft)=250(Temp. - Dew Pt.) to estimate the height. The Height that air contains a perceptible quantity of cloud particles to become visible. This will be calculated even if conditions do NOT permit cloud formation.
 +The unit for solar radiation is Watts per Square Meter
Other Current Conditions Links
Detailed Obs. Precip. Obs.
 		Temperature Obs.
 		Barometer Obs.
 		Wind Obs.
Rel. Humidity Obs.
 		Solar Radiation
 		Current Virginia Obs.
 Surface Wetness
 		Snowfall Obs.
Observations from a Vantage Pro sensor located
in a weather shelter at five feet above ground		 Based on the rate of heat loss from exposed skin
caused by effects of wind & cold.
24_Hour Temperature Graph 24-Hour Wind Chill Graph
Relationship--The Faster and the larger the pressure change the stronger the wind!
High Wind Speed Graph Barometric Pressure Graph
The direction from which the wind is blowing
using only eight points of the compass.		 A measure of both the direct radiation
and & scattered radiation
For more see
Wind Direction Graph Solar Radiation Graph
Max. amount of precip. during a 5 minute period Precip. rate in inches per hour for last 24 hours.
Precip. Graph Precip. Rate
Surface wetness hrs. (15=wet)
From Dew and Precipitation 		Percent of water vapor in the air compared
to the maximum amount it can hold
Surface Wetness Relative Humidity Graph