Sunday Storm System

A low pressure system is organizing over Texas today, and will strengthen along the Gulf Coast into this weekend as it tracks eastward. This storm will turn northeast Saturday and cross through Georgia, the Carolinas, and onto Virginia by early Sunday morning, bringing rain to the region. The latest data still indicates that the precipitation mode will be rain in Central Virginia, as temperatures will remain above freezing both at the ground and in a deep enough layer above the surface. Rain is expected to overspread the Commonwealth from the Carolinas by early Sunday morning, and rain will be likely through the entire day while the low tracks through the area. Here is a snapshot of the low's expected position on Sunday morning:

Major Earthquake In Haiti

A class "major" earthquake of magnitude 7.0 struck 10 miles Southwest of Port-au-Prince, Haiti Tuesday night at 4:53 p.m. local time, shortly before dark fell over the Caribbean island of Hispaniola. This earthquake was pretty much a worst-case-scenario because of several factors. The initial 7.0 was shallow, only 6.2 miles deep. Also, it was devastatingly close to the highest population density in the affected region, the capital of Haiti. Finally, this was a "strike-slip" type of earthquake, where two plates slide past each other in a horizontal fashion instead of one being uplifted by the other.

When this happens, buildings are shaken side-to-side instead of up and down. This type of horizontal shaking of a structure usually leads to building failure, as the weight of the roof causes an implosion and walls collapse. In Haiti, most buildings are not reinforced concrete, and not earthquake-resistant. This likely means many structures failed in the initial earthquake. If they did not do so in that first major quake, they probably later collapsed during one of the 35 aftershocks (as of 10 a.m.) that occurred overnight, 14 of which were magnitude 5.0 or greater. You can see a full list of all the earthquakes and aftershocks here. The initial 7.0 was felt in the surrounding countries in the Caribbean, as displayed here on the Shake Map:

For your reference, here are the classes of earthquakes on the Richter Scale, with the strength of the earthquake felt increasing logarithmically:

This part of the Caribbean has several fault lines running through it, which makes it particularly prone to seismic activity:

Weekend Outlook

We are watching for a potential storm system this weekend that will develop along the Gulf Coast at the end of the week, then track northeast along the southeast Atlantic Coast toward Virginia late Saturday night into Sunday. The track of this low is still uncertain, but it does appear from the latest data that it will move close enough to the Commonwealth to bring us a chance for rain Sunday. Depending on the timing and proximity of the low, precipitation type could be an issue. At this time, it appears rain will be the primary mode, but with surface temperatures expected to be near freezing Sunday morning, there is at least the potential for some icy spots if rain has already begun falling early Sunday. This is a forecast snapshot of Sunday morning with the approaching low from the south:

Depending on the timing of the rain's arrival, temperatures may have already risen back above freezing Sunday morning by the time it begins raining. Or, if the system accelerates into the region sooner, temperatures could still be around freezing when rain begins. Thus, precipitation type will depend on the track and timing of this system. We will provide updates through the week as the storm develops along the Gulf Coast and heads northeast.