<div class="eI0"> <div class="eI1">Model:</div> <div class="eI2"><h2>Times Series from the ECMWF</h2></div> </div> <div class="eI0"> <div class="eI1">Updated:</div> <div class="eI2">Update monthly</div> </div> <div class="eI0"> <div class="eI1">Greenwich Mean Time:</div> <div class="eI2">12:00 UTC = 08:00 EDT</div> </div> <div class="eI0"> <div class="eI1">Resolution:</div> <div class="eI2">1.0° x 1.0°</div> </div> <div class="eI0"> <div class="eI1">Parameter:</div> <div class="eI2">Lifted Index</div> </div> <div class="eI0"> <div class="eI1">Description:</div> <div class="eI2"> <!--begin info text LI--> <p> The Lifted Index (LI) is defined as a rising parcel's temperature when it reaches the 500 millibars level (at about 5,500m or 18,000 feet asl), subtracted from the actual temperature of the environmental air at 500 mbar. If the Lifted Index is a large negative number, then the parcel will be much warmer than its surroundings, and will continue to rise. Thunderstorms are fueled by strong rising air, thus the Lifted Index is a good measurement of the atmosphere's potential to produce severe thunderstorms. </p> <p> <!--begin LI table--> <body> <table width="400" cellspacing="0" cellpadding="0" border="0"> <tr height="30" bgcolor="#E5E5E5"><!-- Row 1 --> <td colspan="4"><font size="3" face="Arial, Helvetica" color="#0000FF">The Lifted Index (LI)</td> </tr> <tr height="30"><!-- Row 2 --> <td width="17%" valign="top"><font size="1" face="Arial, Helvetica"><center>RANGE IN K</center></td> <td bgcolor="#E5E5E5" width="20%" valign="top"><font size="1" face="Arial, Helvetica"><center>COLOR</center></td> <td width="30%" valign="top"><font size="1" face="Arial, Helvetica"><center>AMOUNT OF INSTABILITY</center></td> <td widht="33%" valign="top"><font size="1" face="Arial, Helvetica"><center>THUNDERSTORM PROBABILITY</center></td> </tr> <tr height="25" bgcolor="#E5E5E5"><!-- Row 3 --> <td valign="top"><font size="1" face="Arial, Helvetica"><center>more than 11</center></td> <td valign="top"><font size="1" face="Arial, Helvetica" color="#00A1E6"><center>BLUE</center></td> <td valign="top"><font size="1" face="Arial, Helvetica"><center>Extremely stable conditions</center></td> <td valign="top"><font size="1" face="Arial, Helvetica"><center>Thunderstorms unlikely</center></td> </tr> <tr height="25"><!-- Row 4 --> <td valign="top"><font size="1" face="Arial, Helvetica"><center>8 to 11</center></td> <td bgcolor="#E5E5E5" valign="top"><font size="1" face="Arial, Helvetica" color="#00C7C7"><center>LIGHT BLUE</center></td> <td valign="top"><font size="1" face="Arial, Helvetica"><center>Very stable conditions</center></td> <td valign="top"><font size="1" face="Arial, Helvetica"><center>Thunderstorms unlikely</center></td> </tr> <tr height="25" bgcolor="#E5E5E5"><!-- Row 5 --> <td valign="top"><font size="1" face="Arial, Helvetica"><center>4 to 7</center></td> <td bgcolor="#E5E5E5" valign="top"><font size="1" face="Arial, Helvetica" color="#00D18C"><center>GREEN</center></td> <td valign="top"><font size="1" face="Arial, Helvetica"><center>Stable conditions</center></td> <td valign="top"><font size="1" face="Arial, Helvetica"><center>Thunderstorms unlikely</center></td> </tr> <tr height="25"><!-- Row 6 --> <td valign="top"><font size="1" face="Arial, Helvetica"><center>0 to 3</center></td> <td bgcolor="#E5E5E5"valign="top"><font size="1" face="Arial, Helvetica" color="#A1E633"><center>LIGHT GREEN</center></td> <td valign="top"><font size="1" face="Arial, Helvetica"><center>Mostly stable conditions</center></td> <td valign="top"><font size="1" face="Arial, Helvetica"><center>Thunderstorm unlikely</center></td> </tr> <tr height="25" bgcolor="#E5E5E5"><!-- Row 7 --> <td valign="top"><font size="1" face="Arial, Helvetica"><center>-3 to -1</center></td> <td bgcolor="#E5E5E5" valign="top"><font size="1" face="Arial, Helvetica" color="#E6DC33"><center>YELLOW</center></td> <td valign="top"><font size="1" face="Arial, Helvetica"><center>Slightly unstable</center></td> <td valign="top"><font size="1" face="Arial, Helvetica"><center>Thunderstorms possible</center></td> </tr> <tr height="25"><!-- Row 8 --> <td valign="top"><font size="1" face="Arial, Helvetica"><center>-5 to -4</center></td> <td bgcolor="#E5E5E5" valign="top"><font size="1" face="Arial, Helvetica" color="#F08229"><center>ORANGE</center></td> <td valign="top"><font size="1" face="Arial, Helvetica"><center>Unstable</center></td> <td valign="top"><font size="1" face="Arial, Helvetica"><center>Thunderstorms probable</center></td> </tr> <tr height="25" bgcolor="#E5E5E5"><!-- Row 9 --> <td valign="top"><font size="1" face="Arial, Helvetica"><center>-7 to -6</center></td> <td bgcolor="#E5E5E5" valign="top"><font size="1" face="Arial, Helvetica" color="#F00000"><center>RED</center></td> <td valign="top"><font size="1" face="Arial, Helvetica"><center>Highly unstable</center></td> <td valign="top"><font size="1" face="Arial, Helvetica"><center>Severe thunderstorms possible</center></td> </tr> <tr height="25"><!-- Row 10 --> <td valign="top"><font size="1" face="Arial, Helvetica"><center>less than -7</td> <td bgcolor="#E5E5E5" valign="top"><font size="1" face="Arial, Helvetica" color="#FF00FF"><center>VIOLET</td> <td valign="top"><font size="1" face="Arial, Helvetica"><center>Extremely unstable</td> <td valign="top"><font size="1" face="Arial, Helvetica"><center>Violent thunderstorms, tornadoes possible</td> </tr> </table> <!--end LI table--> </p> <!--end info_text LI--> </div> </div> <div class="eI0"> <div class="eI1">Introduction to seasonal forecasting:</div> <div class="eI2">The production of seasonal forecasts, also known as seasonal climate forecasts, has undergone a huge transformation in the last few decades: from a purely academic and research exercise in the early '90s to the current situation where several meteorological forecast services, throughout the world, conduct routine operational seasonal forecasting activities. Such activities are devoted to providing estimates of statistics of weather on monthly and seasonal time scales, which places them somewhere between conventional weather forecasts and climate predictions. <br> <br> In that sense, even though seasonal forecasts share some methods and tools with weather forecasting, they are part of a different paradigm which requires treating them in a different way. Instead of trying to answer to the question "how is the weather going to look like on a particular location in an specific day?", seasonal forecasts will tell us how likely it is that the coming season will be wetter, drier, warmer or colder than 'usual' for that time of year. This kind of long term predictions are feasible due to the behaviour of some of the Earth system components which evolve more slowly than the atmosphere (e.g. the ocean, the cryosphere) and in a predictable fashion, so their influence on the atmosphere can add a noticeable signal.<br> ©<a href="https://confluence.ecmwf.int/display/COPSRV/Seasonal+forecasts+and+the+Copernicus+Climate+Change+Service#SeasonalforecastsandtheCopernicusClimateChangeService-Introductiontoseasonalforecasting">Copernicus</a> </div></div> </div>