Tuesday, March 30, 2010

Warm Temperatures... Thunderstorms by Friday!

There has been much discussion in the chase community about the upcoming trough and its' associated features and its' severe weather potential. This discussion has been ongoing since the trough was a gleam in the GFS way back at 300+ hours. This would appear to be the first trough in perhaps many that is signaling the idea of switching out of winter and into a spring pattern. This pattern change is welcomed in such a year that thus far has been terribly slow in severe weather per SPC yearly climatology. Many questions remain about this first trough and still being 3.5 days as of this mornings (12z) model run this isn't necessarily unusual. I do hope that by tomorrow evening the models were at least begin to agree upon the more synoptic features of the event. Many questions have been brought forth regarding this Friday and while a few of them will likely not be answered until the morning of, we can at least speculate to what the results will be given certain conditions.

Moisture was an initial concern, and while the moisture is not expected to be significant there would still appear to be sufficient surface and mixed-layer moisture available for severe weather given the strong dynamics. Wind shear was a concern and still is a large concern given model forecasts of south-southwest winds from 850hPa through 500hPa. Latest trends have at least backed surface winds to a southeast direction during the afternoon Friday, which is dramatically helping the 0-1km shear values. However, given the highly uniform wind speeds without some additional turning in the 850-700hPa layer the surface winds may not be much of a factor. Instability has become somewhat of an issue given such dynamic cooling takes place ahead of the trough that there will not be a sufficient cap to allow for clear skies into the afternoon. A resulting precipitation/cloud shield in conjunction with warm temperatures ~800hPa would appear to be limiting the overall instability. This last detail is a question that may not be answered until the morning of, given the highly questionable model forecast cloud cover and precipitation. Nonetheless with all of the questions abound it would still appear that a severe weather event may likely unfold across the Southern Plains and perhaps even parts of the Central Plains. There is no doubt that with such a slow season ongoing and the location of the setup that many chasers will be out regardless.

In the meantime it is time to enjoy some very warm weather! High temperatures today ranged from the lower 70s along the Mississippi to the mid 80s along the western High Plains. Warm air and moisture will continue to stream northward as south winds continue to be sustained 10-20 mph with gusts to 30 mph both Wednesday and Thursday. Expect temperatures tomorrow to be a few degrees warmer than today, and Thursday's high once again be well above normal for most areas.

Additional updates will be likely tomorrow and through the remainder of the week in regards to the upcoming potential for severe weather.

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