Wednesday, May 06, 2009

Another "messy" day.

Another day with ongoing storms to mess-up the afternoon convective environment. Attention was focused over the southeastern and mid-Atlantic states. While the observations led to plenty of forecast uncertainty, today was notable in that it was the first day of the Spring Experiment where the different 0000 UTC models showed some consistency...but of course just because they were consistent doesn't mean they'll produce good forecasts.

One of the more intriguing forecasts was from the 4-km WRF-NMM which developed several discrete, rotating storms along a warm front located in northern North Carolina. The other models also produced storms in this region, but they were smaller, more numerous, and not nearly as organized. The behavior of the NMM can probably be attributed to its surface wind field, which predicted a more easterly wind component north of the warm front (compared to the other models), thus, enhancing shear along the boundary. As of this posting, there are numerous storms in that area, but I do not believe any are supercellular.

Once again, the 1200 UTC model runs were out to lunch and didn't provide any helpful guidance, probably due to ongoing convection influencing initialization. I don't think either forecasting team used the 1200 UTC model runs as guidance for the final forecast products.

It seems like we're just waiting for a day without morning convection. Perhaps then, the 1200 UTC models will have a better handle on the situation and can provide useful guidance.

Craig S

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