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How to use forecasts published be the NWS (National Weather Service):

    Forecasts published by the National Weather Service (at www.weather.gov) are in the form of Grid points.  That means that when you click on a place on the map it takes you to the nearest town/city.  This allows you to compare forecasts from around the county to determine temperature changes, etc.  Please note the the Sterling forecast office is one of very few that use this system.  I recommend taking forecasts from around surrounding areas and comparing them for long term periods (2 or more days away).  All NWS offices use a documentation called a forecast discussion.  This gives you incite as to why the forecast was changed, left the same, etc.  However these are done quick and they use many abbreviations that take time the decode and understand for first time users.  I currently am working on a section dedicated to decoding these abbreviations, to make it easier for beginners.


How to read radar precipitation types on non-winter radars.

    The first thing to look for on radars that have no snow/ice/rain separations in color is the returns of the echoes that the radar is showing. is the key and colors on it so you can tell heavy from light precipitation.  If you see strong echoes, typically reds and yellows, and the color is concentrated over an extremely large area or it makes up an entire band of precipitation then more than likely this is sleet.  This happens because the ice pellets of sleet send back very strong echoes.  Snow usually has lighter overall echoes simply because it does not have the water content of rain so the echoes are not as strong.  Rain on the other hand is the complete opposite of snow, it usually appears as dark greens and sometimes isolated yellow in heavier precipitation bands and thunderstorms.


September 24, 2001 Northern  Virginia, DC, and Maryland tornado event.  (links directly to NWS)


You can estimate wind speeds by using this scale called the Beaufort Scale.   During Isabel, I used this scale to estimate a peak wind gust of around 75mph (note this may be some what inaccurate as the scale only goes up to around 65, so I had top estimate the difference between the actual speed and 65).  If anybody has an actual speed that was recorded or estimated, I would like to have it to post.

       25-30mph- large branches in trees move

      30-40mph- makes it hard to walk into the wind.  Entire trees moving (typically taller ones)

     40-45moh- almost impossible to walk against the wind.  Small twigs and small branches may break.

     45-55mph- medium sized branches that are weak may break.  Shingles may be blown off.

     55-65mph (beginning of severe criteria)- small trees uprooted and large branches break.  Some structural damage may occur.

    >65mph- roofs may be blown off weak structures.  Large trees uprooted.


NOAA Weather Radio's can save your life.  You can get them for almost little of nothing now days, but what exactly is it?  It is basically a link to the NWS that is fast and reliable.  The high volume alert siren (usually 90-120 decibels) alerts you when severe weather warnings/watches or statements are issued.  Of course you can get the same information from TV, but there is a delay of sometimes as much as 5 minutes before the warning is broadcast.  That is a heck of a lot of time is there is a tornado coming for you.  It is also battery operated and AC powered.  This means you can put batteries in the thing and plug it in.  When the power goes out your link to valuable information has not been lost.  I recommend Midland (R), First Alert (R), ShareCom (R), or Organ Scientific (R) companies.  Before you buy one though, make sure your area is covered here.  You should be either in the white or green.  Red means you can not get a reliable signal from that location.