Tuesday, May 15, 2012

Tropical Storm Aletta Shifts Out to Sea; New Development Possible

Tropical Storm Aletta is currently moving westward in the middle of the Pacific Ocean, far west of Mexico, pretty much in the middle of nowhere. Winds are sustained at a fair 45 MPH, making for a moderately weak tropical storm. The system is expected to fade out as the westward movement continues, with an eventual turn to the north, before the system becomes post-tropical.

And of course, because the East Pacific needs more storms than the Atlantic (which should be achievable with the now-dead La Nina), we have an area of potential development over the next several days. While it is at 10% now, the National Hurricane Center has indicated that development appears possible over the next several days.

And lastly, we have an area of weak showers drifting around in the far northeast Atlantic. Yes, there is a circulation judging by visible clouds, but there is also a patch of tightly wrapped showers within the system. Needless to say, there is a 0% chance for development as it isn't even classified as an invest at this point.


Severe Weather Targets Chicago, Milwaukee Today

There is a slight risk of severe thunderstorms today from northern Illinois into southern Wisconsin and southwest Michigan. Extreme northwest Indiana and eastern Iowa are also included in this risk.

Current surface analysis indicates a cold front will be sweeping south and east into the area highlighted, bringing what the Storm Prediction Center calls 'supercells and/or severe multicell line segments' to the region.

Considering the area highlighted is within warm temperatures but not so high humidities, these storms should not be incredibly rainy, so flash flooding is not anticipated in most areas. However, heavy rainfall in an area cannot be ruled out.
When the SPC is talking about these 'severe multicell line segments', they are discussing bowing segments of storms.

At around 6:00 PM CDT this afternoon, the SPC's WRF-NMM model is projecting that a line of strong storms will ignite in the region and likely produce some severe activity in the region.

The same WRF-NMM run off a different machine tells that the storms should be based farther west. Considering that the first image is from what I consider the 'operational' forecast, and it seems to be in line with the SPC, I will go with that solution.