Model:

Ensemble forecast charts of several different numerical weather prediction (NWP) models

Güncelleme:
2 times per day, from 05:00 and 17:00 UTC
Greenwich Mean Time:
12:00 UTC = 14:00 EET
Resolution:
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

Spaghetti plots:
are a method of viewing data from an ensemble forecast.
A meteorological variable e.g. pressure, temperature is drawn on a chart for a number of slightly different model runs from an ensemble. The model can then be stepped forward in time and the results compared and be used to gauge the amount of uncertainty in the forecast.
If there is good agreement and the contours follow a recognisable pattern through the sequence then the confidence in the forecast can be high, conversely if the pattern is chaotic i.e resembling a plate of spaghetti then confidence will be low. Ensemble members will generally diverge over time and spaghetti plots are quick way to see when this happens.

Spaghetti plot. (2009, July 7). In Wikipedia, The Free Encyclopedia. Retrieved 20:22, February 9, 2010, from http://en.wikipedia.org/w/index.php?title=Spaghetti_plot&oldid=300824682
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).