Wednesday, August 1, 2012

Decent Severe Weather Threat Exists Across Great Lakes This Weekend

A decent severe weather threat looks to be evolving over the Great Lakes this weekend, as a strong low pressure system looks to swing south from Canada into the Northern Plains.

As this disturbance moves into the Northern Plains, wind shearing looks to develop across much of the Great Lakes. That, combined with instability and widespread favorable 850mb winds, looks to provoke a potentially interesting severe weather situation this weekend.

A squall line looks to develop along a cold front attached to the disturbance, which, feeding on the available instability and in the midst of favorable lower level winds, should be able to produce a severe weather threat that will cross the severe weather spectrum, including a chance of tornadoes. However, pinpointing the exact risks in exact areas is too tricky this far out, and should be determined around the Friday timeframe.

The Storm Prediction Center has outlined a long range severe weather risk area over much of the Northeast on Sunday. The way this is projected by the Storm Prediction Center, along with GFS model forecasts, shows that either a squall line or several bowing clusters may be possible over the weekend in the Northeast. This would be yet another time that a damaging wind event hits the northeast part of the nation in a short period of time.


Tropical Depression FIVE Forms in Atlantic; Mexico Landfall Possible

Tropical Depression FIVE has formed in the Atlantic Ocean this afternoon, after a couple days of close monitoring by the National Hurricane Center.

Satellite imagery indicates strong convection ongoing in the center of the system, with outer convection beginning to show signs of wrapping around the center, indicating the presence of a center of circulation. Now that it has been classified as a depression, we will have to be looking for additional wrapping of convection around the center to see how strong the system is getting.

The track and intensity forecast from the National Hurricane Center shows TD-FIVE moving west-northwest into the Caribbean, in the process gaining tropical storm strength. This would make the system named Tropical Storm Ernesto. At that point, the track looks to try and take a more northwest turn, while strengthening into a hurricane at the end of the forecast point, which is about 5 days out.

Other model forecasts generally agree with the NHC's forecasts, but the members associated with the HWRF image appear less inclined to bring on hurricane strength to Ernesto. The FIM model, on the top, shows the track of Ernesto and how it is developed nearly into a hurricane. It will take a few days for more short range models like the HWRF/NAM to get this storm well into its timeframe, but for now it does appear that tropical storm strength is likely in the next day or two.
What is concerning is the FIM's landfall on Mexico. It is certainly possible, given how far south TD-FIVE is at the moment and its projected track by the NHC and HWRF members, but a landfall onto the Yucatan Peninsula could greatly affect countless tourists who go to enjoy the beaches of the Yucatan Peninsula.


BREAKING: Tropical Depression FIVE Forms

Invest 99 has developed into Tropical Depression FIVE, and is forecast by the National Hurricane Center to move through the Caribbean and possibly towards the Gulf of Mexico. A post concerning TD-FIVE will be out this evening when the models obtain data from the system.


'Ernesto' May Form Later Today

TD-FIVE Has Formed. Click Here

Invest 99 is approaching the point of tropical depression formation, and this could transform into Tropical Storm Ernesto in the next several days. Satellite imagery indicates enhanced convection in the center of this storm system, with a very slight circulation motion seen in the northern flank of the system, as upper level clouds appear to have a small spin to them.

Shearing values over the eastern Atlantic are fairly elevated, with widespread values of 10-25 knots of shearing. This shearing will enhance storms, but getting beyond the 30 knot benchmark may hurt the invest's chances of developing into a tropical system. Tendencies of shearing indicate an increasing shearing region approaching the Caribbean that the invest may have to go through.

Weather model forecasts on Invest 99 are projecting the system to move roughly west-northwest for a while, before a more northwest motion is encountered. During this movement into the Caribbean, model forecasts are scattered in the long range, but have indications of a strength of Invest 99 in the general 45-55 knot wind speed area, bringing the invest to tropical storm strength and bringing 'Ernesto' to life.