Upper wind forecasts

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mingram
Posts: 987
Joined: Mon Sep 07, 2009 10:46 pm
Location: Washington, DC

Upper wind forecasts

Post by mingram »

A few PG pilots flew Daniels on Saturday 1/4 and noticed the wind was lower than forecast. The NOAA ground forecast was 13mph peak. The ADDS forecast for 3000 feet was in the 20-30 knots range (dark blue). Weather.nostepper.com showed the same. PGs typically take that strong upper wind forecast as a sign that the site will be blown out for PG.

Actual readings from Wunderground at Little Edge Farm showed gusts were never much more than 10 mph.

Do you think the forecast was over estimated or maybe upper winds aren't a concern in the winter because we're not getting as high?

I got permission to repost Laszlo's response:
"I think the models are systematically overestimating ground windspeed in the winter. In the warmer seasons, dark blue at 3000 feet on ADDS is a sure indication of blown out conditions. In the winter, I noticed that in many cases Daniels (and WS) ends up with 5-10 mph conditions at launch even when No stepper at launch level and ADDS at 3000 feet predict much stronger wind. Really don't know the reason. One possibility is the heavier cold airmass close to ground level is more resistant to the fast moving air at upper levels. Just speculation. But the effect seems to be real."
Matt Ingram
CHGPA President
P4 Observer
804.399.5155
mingram@vt.edu
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