What??? No Heat Advisory?July 17th, 2012 at 8:11 am by Jeremy Wheeler under Weather
It’s true. We will be very hot and humid today, and the heat index will be over 100. But there is no heat advisory for the region. Huh?The reason is that a heat advisory has a specific criteria. They are issued by the National Weather Service. The heat index has to be at 105 degrees or higher for about 3 hours or more. While we will have a heat index up near 105 in some of our inland areas today, it will probably only be for a couple of hours. The setup for today is a large area of high pressure or a Bermuda high which is building in stronger this afternoon compared to yesterday. We’ll have more sunshine than yesterday and a west-southwest wind at 5-10mph. Aloft the winds will be more westerly. This will pull in a warming/sinking (downsloping) wind off of the Appalachian mountains. So with a little mixing we will luckily pull in some dry air from the mid levels this afternoon and it will hopefully mix down to the surface (A LITTLE BIT). So instead of dew points in the 70s like this morning we’ll change them to the upper 60s. This will help some, even though it seems minor.
High temperatures will be in the mid-upper 90s in the metro with solid upper 90s inland. There may even be a couple of 100s between Williamsburg and Richmond. So the heat index will be about 99-104 in the metro area and higher inland. Tomorrow we’ll shift these winds around just so slightly, but it will be enough to let the humidity increase. So heat advisories are likely tomorrow with a heat index up to 107 possible in the metro area.
A cold front will approach from the north late Thursday. Showers and storms are likely late Thursday through late Friday. A few storms may linger into Saturday morning, but should end by midday (stay tuned for updates). Clouds and rain will drop the temperatures a bit on Thursday, but the front will drop our highs to the mid 80s by Friday. We’ll stay in the mid 80s through Sunday. It should be a nice weekend unless the front stalls out. Seems like that’s been happening a lot lately right over us. It’s made for a tough forecast lately.
Meteorologist: Jeremy Wheeler