Forecast Exercise: T1 Method

Hypothetical sounding for wind gust forecast exercise

Using this morning sounding, use the T1 method to forecast the maximum wind gust speed and direction associated with anticipated afternoon convection. You can open the Interactive Skew-T with this sounding.

Step 1: Determine T1.
Enter your answer in the text box below, then click Done.

T1 = °C  

The correct answer is 12°C.
With no inversion top within 200 hPa of the surface, we proceed dry adiabatically from the 850 hPa temperature to the surface to yield TMAX = 23°C. From TMAX, proceed up a moist adiabat to 600 hPa, where the resulting temperature value is +4°C. The observed temperature at 600 hPa is -8°C. The difference is +4°C-(-8°C) = 12°C = T1.

Step 2: Compute V1.
Enter your answer in the text box below, then click Done.

V1 = kt  

The correct answer for V1 is 45 knots.
With T1=12°C, then:
V1 = 13 * sqrt(12) = 45.03 knots.
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