Wednesday, June 8, 2011

Nearcast training for severe

UW-CIMSS scientist Ralph Petersen explaining the Nearcast product to EFP participants

This morning UW-CIMSS scientists Ralph Petersen and Bob Aune sat down with the EFP's severe desk to help train the participants on how to use the Nearcast product during morning forecast operations. UW-CIMSS provides us with 10 fields from the Nearcast product, which includes individual layers of theta-e and preciptable water (PW), which are then differenced to provide the differential theta-e and PW water fields that we typically use for forecasts. The most effective way to help forecasters understand what they are looking at in these differential fields is to start with the individual layer PW and theta-e fields and then the forecaster can mentally calculate the differences and compare to what the product is showing them. Ralph and Bob helped the participants understand how the Nearcast can assist them in making their forecasts by pointing out that the Nearcast fields will show you where relatively convectively stable and unstable areas are. Because no forcing mechanisms are included within the Nearcast's output, it doesn't guarantee where convection will occur, but it can help narrow down where you should be focusing your attention. If there is an area of strongly stable air, you're not likely to have any deep convection, even if there is some sort of light forcing present. This may be especially useful within SPC operations for forecasters issuing mesoscale discussions (MD) to determine where a severe thunderstorm or tornado watch will or will not be needed. It may also be useful during the early afternoon convective outlook updates to help trim areas that will not be expected to have thunderstorms later during that day. Following the group training, Steve Weiss (SPC SOO) asked if I would be willing to work with the forecasters in operations this summer in exposing this product to them. In addition, we expect to provide a training session within the SPC's bi-annual forecaster training this fall to help expose all of the SPC personnel to the product.

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