<div class="eI0"> <div class="eI1">Modelo:</div> <div class="eI2"><h2><a href="http://www.emc.ncep.noaa.gov/GFS/doc.php" target="_blank">GFS</a> (Global Forecast System) Global Model from the "National Centers for Environmental Prediction" (NCEP)</h2></div> </div> <div class="eI0"> <div class="eI1">Actualização:</div> <div class="eI2">4 times per day, from 3:30, 09:30, 15:30 and 21:30 UTC</div> </div> <div class="eI0"> <div class="eI1">Greenwich Mean Time:</div> <div class="eI2">12:00 UTC = 12:00 WET</div> </div> <div class="eI0"> <div class="eI1">Resolution:</div> <div class="eI2">0.5° x 0.5° for forecast time <= 384 hrs</div> </div> <div class="eI0"> <div class="eI1">parâmetro:</div> <div class="eI2">Lifted Index</div> </div> <div class="eI0"> <div class="eI1">Descrição:</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">GFS:</div> <div class="eI2">The Global Forecast System (<a href="http://www.emc.ncep.noaa.gov/gmb/moorthi/gam.html" target="_blank">GFS</a>) is a global numerical weather prediction computer model run by NOAA. This mathematical model is run four times a day and produces forecasts up to 16 days in advance, but with decreasing spatial and temporal resolution over time it is widely accepted that beyond 7 days the forecast is very general and not very accurate.<br> <br> The model is run in two parts: the first part has a higher resolution and goes out to 180 hours (7 days) in the future, the second part runs from 180 to 384 hours (16 days) at a lower resolution. The resolution of the model varies in each part of the model: horizontally, it divides the surface of the earth into 35 or 70 kilometre grid squares; vertically, it divides the atmosphere into 64 layers and temporally, it produces a forecast for every 3rd hour for the first 180 hours, after that they are produced for every 12th hour. </div></div> <div class="eI0"> <div class="eI1">NWP:</div> <div class="eI2">A previsão numérica do tempo usa o estado instantâneo da atmosfera como dados de entrada para modelos matemáticos da atmosfera, com vista à previsão do estado do tempo.<br> Apesar dos primeiros esforços para conseguir prever o tempo tivessem sido dados na década de 1920, foi apenas com o advento da era dos computadores que foi possÃvel realizá-lo em tempo real. A manipulação de grandes conjuntos de dados e a realização de cálculos complexos para o conseguir com uma resolução suficientemente elevada para produzir resultados úteis requer o uso dos supercomputadores mais potentes do mundo. Um conjunto de modelos de previsão, quer à escala global quer à escala regional, são executados para criar previsões do tempo nacionais. O uso de previsões com modelos semelhantes ("model ensembles") ajuda a definir a incerteza da previsão e estender a previsão do tempo bastante mais no futuro, o que não seria possÃvel conseguir de outro modo.<br> <br>Contribuidores da Wikipédia, "Previsão numérica do tempo," Wikipédia, a enciclopédia livre, <a href="http://pt.wikipedia.org/w/index.php?title=Previs%C3%A3o_num%C3%A9rica_do_tempo&oldid=17351675" target="_blank">http://pt.wikipedia.org/w/index.php?title=Previs%C3%A3o_num%C3%A9rica_do_tempo&oldid=17351675</a> (accessed fevereiro 9, 2010). <br> </div></div> </div>