General Map Information

Time Stamp

All maps on this page have a time stamp at the bottom of the page, which indicates date for which the map is valid. For example, the time stamp "Valid 020901/1800V030" can be decoded as follows: 02 is the year (2002), 0901 is the month and day (Sept, 01), 1800 is the hour in UTC, 030 is the forecast hour (30). The forecast hour indicates how many hours after model initialization this forecast represents.

Isopleths

All lines or contours on the following maps are isopleths. An isopleth is a line drawn on a map through all points of equal value of some measurable quantity. An example would be the isobars (iso->equal, bar->pressure) on a surface pressure map.

Description of Each Map

Surface Analysis – Precip

The estimated mean sea level pressure in millibars (mb) is given by solid purple lines (isobars). The accumulated precipitation in inches, for the previous 6 hours is given as color fill using a non-linear scale.

Surface Analysis – Thickness

The estimated mean sea level pressure is given by solid black lines (isobars). The 1000/500 thickness, which represents the vertical distance between the 1000 and 500mb levels, is given as color fill.

850 mb temp, hght, wind

The height in decameters of the 850mb pressure surface is contoured by solid black lines. The air temperature, in degrees Celsius, is given as color fill. Wind barbs indicate wind direction and wind speed in knots.

700 mb omega, hght, wind

The height in decameters of the 700mb pressure surface is contoured by solid purple lines. The vertical velocity of the air in microbars per second is given as color fill. Positive values represent upward movement or rising air, and negative values represent sinking air. Wind barbs indicate wind direction and wind speed in knots.

700 mb rh, hght, wind

The height in decameters of the 700mb pressure surface is contoured by solid purple lines. The relative humidity is given as color fill. Wind barbs indicate wind direction and wind speed in knots.

500 mb vort, hght, wind

The height in decameters of the 500mb pressure surface is contoured by solid purple lines. The relative vorticity is given as color fill. Wind barbs indicate wind direction and wind speed in knots.

250 mb hght, isotachs

The height in decameters of the 250mb pressure surface is contoured by solid purple lines. Areas of similar wind speed are color filled. Wind barbs indicate wind direction and wind speed in knots. The sub-tropical jet stream is often visible in this map between 25 and 35 degrees north.