Wednesday, August 16, 2017

Day 2 TCF discussion: medium coverage and broad sparse areas

Though a quieter day weather-wise, the lighter load in product issuance allowed for some interesting exploration of TCF and the long-range concept. The first was a discussion about including medium coverage in the long-range. This was one of the forecasts issued for 24 hours out:

Note in particular the medium coverage area near Minneapolis Center. There has been debate as to whether the long-range forecast should only be high confidence of sparse coverage given the inherent uncertainty in the models. However, in this case the forecaster stated that despite the uncertainty in location, judging by the synoptic scale pattern and agreement in the long-range models of several rounds of convection, confidence was high for medium coverage somewhere in the area.

From a user perspective, it was noted that the uncertainty in the location doesn't so much matter. Just the fact that the forecaster was confident in medium coverage, particularly over a busy terminal like Minni, would provide value. That confidence would indicated to planners that there would be an area to deal with the next day. Additionally, it differentiates the synoptic scale type convection scenario from the typically summertime airmass convection that often occurs in the Southeast U.S.

The second discussion point was related to the airmass convection. The forecaster generated a broader area of sparse coverage over the Southeast U.S., broader than is typically done because of the uncertainty. In this case, the users looked and immediately saw the many terminals covered within these area; Atlanta, Jacksonville, Birmingham, Hunstville, etc. It was noted that seeing so many terminals affected many alarm traffic flow managers, despite that it was likely realistic given the summertime airmass convection. They suggested that maybe instead of such a broad area, a series of smaller area. This would provide value by indicating that, yes, it would be a summertime airmass convective setup, and prepare traffic flow managers and others for that scenario.

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