WeatherExtreme Forecast Discussion #5 July 19, 2017

Temperatures will struggle to get above freezing in El Calafate over the next 5 days, with some light rain falling late this afternoon and overnight, and again during the early morning hours Friday, when some of it may fall as snow flurries. Conditions are not conducive to flying today and Thursday. There is possibly an opportunity for flight testing on Friday afternoon, but it probably won’t be great. Saturday may be better, but there are fairly large model differences at the moment.

WeatherExtreme Forecast Discussion #4

At launch time Tuesday (1330Z 7/18) it looks to be overcast at FL100. There are major differences between the GFS model and the higher resolution ECMWF. The ECMWF predicts more rain and more clouds at low levels than the GFS. While the GFS forecasts < 1mm precipitation and only thin low clouds during the flight time, the ECMWF has 1-2 mm precipitation and scattered clouds below FL100, increasing toward late afternoon. Both models forecast winds backing with height until becoming westerly above FL100. Wind speeds ranging from 50 kts at FL100 to 80 kts at FL 300.

The high resolution WRF model has light precipitation west of El Calafate, but not much there. Note the the WRF is based on GFS initialization so it is not surprising it would go with less precip in El Calafate. Vertical cross sections show moderate lift over the mountains to about FL260 and moderate to strong lift (1000–1500 fpm) farther east above FL700, but little to no connection between the two.

WeatherExtreme Forecast Discussion #3

Not much has changed in the surface forecast for El Calafate today, but unfortunately the local WRF model is now looking a lot less bullish on today’s updrafts, with updrafts of 600-1000 feet/min below 12 km and only light updrafts or possibly downdrafts between 12 and 18 km. Strong updrafts are still present above 18 km. Monday’s forecast is for fair conditions at El Calafate with a high temperature in the high 30’s (4C) and erratic winds early becoming gusty out of the west in the late afternoon and Monday night. Gusts could exceed 30 kts.

Jim M