NAM (COMPUTER MODEL)
700 MB. MAP (10,000 FT.)
How do I read the map above and what does it all mean?† First of all, this is a computer 700 MB.model forecasting future weather.† In this case, it is forecasting the weather 84 hours in advance.† The forecast is valid 10/29/2009 at 18 UTC. How do we know this?
At the bottom of the map see:
10/26/09 06 UTC 084 HR FCST VALID 10/29/09 18 UTC NCEP/NWS/NOAA.
This is what the numbers mean.
10/26/09 06UTC = the date and time the map was produced.
084 HR FCST= this indicates how many hours out the forecast is valid. (84 hours)
VALID= Thu 10/29/09 18 UTC. This map is valid for 10/29/2009 at 18 UTC.
NCEP, NEW, NOAA= list the branches of the government responsible for the forecasts.
The 700 MB. Map represents a level in the atmosphere of about 10,000 ft. above sea level.
WHAT DO WE SEE? †It looks very much like the 500 MB. Map with the ridges off the west coast and over the southeastern part of the United States. It shows the numbered solid lines that were present on the 500 MB. Map.† Notice, however, THE SHADES OF GREEN on the map. The green represents the relative humidity (moisture) in the atmosphere. LIGHT GREEN indicates a relative humidity of 70% whereas the darker green color represents a relative humidity of 90%. A relative humidity of 70% generally indicates cloudy weather with a few rain or snow showers depending on the season.† It could also indicate some steady light or very light precipitation. A relative humidity of 90% generally indicates cloudy weather with a steady area pf precipitation, which possibly could be heavy.† Precipitation generally begins when the 700 MB. Map indicates the relative humidity is increasing from 70% to 90%.† This, of course, is a very general rule.
HOW MUCH MOISTURE IS PRESENT IN THE UPPER AIR?
(700 MB. MAP (10,000 FT.)
NOW LETíS TRY SOME REAL TIME WEATHER FORECASTING.
Click on this:†† http://www.nco.ncep.noaa.gov/
1. CLICK ON www.nco.ncep.noaa.gov LINK ABOVE. 2. CHOOSE MODEL-NAM 3. SELECT UPPER AIR PARAM.- 700_rh_ht 4. CHOOSE FORECAST HOUR- 000 5. CLICK ON THE "NEXT" BUTTON, THE MAP WILL ADVANCE 3 HOURS, CLICK NEXT AGAIN, THE MAP WILL ADVANCE ANOTHER 3 HOURS.
1. Go back to the original page. (Model Analysis & Forecasts) NAM
2. HOW MUCH MOISTURE IS IN THE AIR? If you want to see how much moisture is in the air, go to the 4th column from the left (700 mb. RH, Ht) The 700 mb. map is approximately at a height of 10,000 feet.
3. ONCE AGAIN DO YOU SEE THE SOLID LINES? (HEIGHT LINES) AND WIND BARBS?
DO YOU SEE 2 SHADES OF GREEN? †The light shade of green indicates a relative humidity of 70%.† Generally an area with 70% INDICATES MOSTLY CLOUDY SKIES WITH THE CHANCE OF A FEW SHOWERS. The areas with dark green indicate a relative humidity of 90%.† Generally, an area with 90% indicates cloudy skies with precipitation. (rain or snow). *PRECIPITATION USUALLY BEGINS WHEN YOUR LOCATION IS AT 70% INCREASING TO 90%.† (RELITIVE HUMIDITY ABOUT 80%).