Monday, March 28, 2011

March 28 Forecast Discussion (Until April 2nd)

Tomorrow, we will be watching the South Plains for severe thunderstorms. This comes as two low pressures connected by fronts cross the Southern United States.
It appears the low level jet stream will be actively pumping humid Gulf air into the atmosphere, thus destabilizing the atmosphere itself. The reason there is a right to believe there will be a severe weather outbreak is how evident that essential low level jet stream will be. Precipitable water (water values in the air) will go past 1 inch of water in the air. I would like to expand the severe weather risk across a larger area of the Southern Plains just due to that, so we will have to keep an eye on everything. This comes on the latest 18z GFS run.
In other news, a low pressure system across the Central Plains will bring snowfall to the region, especially on the eastern side of the low pressure area, which should be located on the extreme western region of Nebraska. Accumulations are expected to be at a maximum of 4 inches, especially in the intersection of the Iowa/Nebraska/South Dakota borders.
A trough moving across the Southeast may create some clouds, but only a sprinkle at best. However, down in South Florida, there will be a watchful eye cast on that area as heavy rains and storms are poised to strike. However, it does not look like it will be a severe weather situation.

In the way of severe weather risks, we will see a widespread but low risk of severe weather in the Southeast. The Storm Prediction Center currently has that area out looked for only a 5% risk of severe storms, which says that, at best, isolated to scattered severe storms may occur. Elevated storms are more of a possibility. The creator of all this precipitation will be a strong low pressure with a classic severe storm set-up. A cold front will extend somewhat directly south, with a warm front horizontally to the east. That said, some elevated storms could occur in the Gulf of Mexico. The low level jet stream will be pumping warm, humid air straight into the mouth of the beast.
Otherwise, a warm front will create a mix of precipitation in the Central Plains going into the 30th.
A very strong low pressure system will slam the West Coast with a true wash-out.  It will get ugly in lower elevations with heavy rains, accompanied by snows in the Mountains.

The Storm Prediction Center has outlined a severe weather outbreak in Florida only. In that area, the SPC indicates an influx of Gulf moisture will create an unstable atmosphere. This will be due to the low level jet stream, creating moisture values of up to 1.75 inches of water in the air. A cold front will provide for a classic severe weather outbreak. As that moves through, strong vertical shear will inspire supercell storms and bow echo storms to develop. In such an unstable environment, a tornadic situation is certainly not out of the question. Strong shear with instability is a ripe environment for tornadoes. We will definitely have to watch this situation for tornadoes.


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