Model:
NAM: North American Mesoscale Forecast System "NOAA"
Güncelleme:
4 times per day, from 0:00, 06:00, 12:00 and 18:00 UTC
Greenwich Mean Time:
12:00 UTC = 14:00 EET
Parametre:
Yükseltgenmiş Indeks
Tarife:
Yükseltgenmiş Indeks (LI), 500 milibara( yaklaşık 5.5000m veya 18,000 fit) ulaşan ve
500mbar’daki çevresel sıcaklık ile gerçek sıcaklığın farkı
ile bulunan, yükselen hava kütlesinin sıcaklığı olarak tanımlanır. Eğer
Yükseltgenmiş Indeks büyük negatif bir sayı ise, yükselen hava kütlesi etrafına
oranla daha sıcaktır ve yükselmeye devam eder. Gökgürültüsü ve orajlar hızla
yükselen hava ile beslenirler, bu yüzden Yükseltgenmiş Indeks atmosferin üretebileceği
potansiyel yıldırım ve şimşek riski açısından iyi bir ölçektir.
The Lifted Index (LI) |
RANGE IN K |
COLOR |
AMOUNT OF INSTABILITY |
THUNDERSTORM PROBABILITY |
more than 11 |
BLUE |
Extremely stable conditions |
Thunderstorms unlikely |
8 to 11 |
LIGHT BLUE |
Very stable conditions |
Thunderstorms unlikely |
4 to 7 |
GREEN |
Stable conditions |
Thunderstorms unlikely |
0 to 3 |
LIGHT GREEN |
Mostly stable conditions |
Thunderstorm unlikely |
-3 to -1 |
YELLOW |
Slightly unstable |
Thunderstorms possible |
-5 to -4 |
ORANGE |
Unstable |
Thunderstorms probable |
-7 to -6 |
RED |
Highly unstable |
Severe thunderstorms possible |
less than -7 |
VIOLET |
Extremely unstable |
Violent thunderstorms, tornadoes possible |
NWP:
Numerical weather prediction uses current weather conditions as input into mathematical models of the atmosphere to predict the weather. Although the first efforts to accomplish this were done in the 1920s, it wasn't until the advent of the computer and computer simulation that it was feasible to do in real-time. Manipulating the huge datasets and performing the complex calculations necessary to do this on a resolution fine enough to make the results useful requires the use of some of the most powerful supercomputers in the world. A number of forecast models, both global and regional in scale, are run to help create forecasts for nations worldwide. Use of model ensemble forecasts helps to define the forecast uncertainty and extend weather forecasting farther into the future than would otherwise be possible.
Wikipedia, Numerical weather prediction,
http://en.wikipedia.org/wiki/Numerical_weather_prediction(as of Feb. 9, 2010, 20:50 UTC).