Saturday, May 5, 2012

Sunday, May 6 Severe Weather Outlook

There is a risk of severe weather for the Lower Great Lakes, Midwest, and Southern Plains into the Arklatex region.

A warm front is expected to pull up warm, humid air from the South and increase instability beyond 3000 j/kg to make for an unstable environment. Lack of shearing will lower the tornado threat, but far northern portions of the risk area may make for a slightly higher threat for rotation in storms. I anticipate the highest instability and dewpoints to be located in the black outlined area, and that should be where storms initiate and are originally the most severe. The biggest risks will be hail and damaging winds.

Storm System to Swing into Southwest; Severe Weather Intentions Unknown

Looking over the maps this morning, I saw the likelihood of a storm system swinging into the Southwest. It looks like a cut off low, and its intentions are unknown. So let's find out.

At around hour 36, or in the morning hours of tomorrow, we see a storm system trying to swing into the Southwest, as characterized by the depressed lines across the West Coast. This does not include the low pressure system on the Canadian border, shown as a few tight circles. As of now, there is a slight spread among the ensembles, but not enough to concern me.

At hour 72, the storm has evolved into a cut off low, shown as a few circles put together in the Southwest. The presence of darker blue colors indicates that the ensembles are starting to differ on this solution. However, since it remains relatively low, I will not worry much about it.

For the next little bit, the storm system remains stationary.

At hour 144, the first thing you notice is the high amount of colors in the northern hemisphere. This indicates a wide variation among individual ensemble members. The higher the colors on the key at the right, the more difference there is. We can still see our storm system, which has now shifted into west Texas, and is shown as a big dip in the lines. At this point, it is possible some severe weather may be produced by this system, however that is not clear at the moment.

Lastly, at hour 168, the storm system has strengthened and is now in Oklahoma, shown as a circle and a depression in the line below that circle. What interests me is the relatively low presence of colors in the storm system, signaling good agreement that this storm system may wash ashore. At this point in time, I believe that warm air should already have been pulled north and showers and storms should have been produced by the system.

Caveats to this storm include the long range timeframe of it, as forecasts beyond 120 hours are not usually the most reliable. Also, I am getting confusing signals from other maps at the same timeframes, making me more reluctant to really go ahead with this potential. Time will, of course, have the final say.