Capping a rainy period
Posted August 13, 2014
Now that some sunshine and drier air is overspreading the area for a few days, I thought I'd take a quick peek at how rainfall has compared to normal recently. It will not surprise a lot of you to see that many of us are running way above normal on rainfall amounts, as we've had several rounds of heavy precipitation recently, including an area of very heavy rain that brought 2-3 inches and a bit more in spots last evening, mainly focused over Wake and Johnston counties, as seen in the map of North Carolina in the first image. After that round of ran brought almost two and a half inches at the RDU airport, the 90-day total there, as seen in the graph in the second image, is over 21 inches! This compares to a normal amount for that period of 11.8 inches, so we've not quite doubled the normal value for that time frame. Of course, this is all related to the frequent development of upper level troughs over the eastern half of the country, which has also had the effect of keeping our temperatures on the mild side.
The last image I'm posting is a map of central North Carolina from the NWS Precipitation Analysis Page that shows the percentage of normal rainfall we've had over the past 90 days, based on a combination of radar rain estimates and surface gauges. The light blue shade over northwest Wake County indicates between 150 and 200% of normal, which fits nicely with the results I noted at the RDU airport. There are a couple of pockets just to our east over Halifax, Pitt and Lenoir counties that have had between 2 and 3 times the norm. However, what also jumps out when you take this larger view is that the rainfall hasn't been evenly distributed everywhere. Southern parts of Orange and Alamance counties, along with much of the area in and around Cumberland county/Fayetteville, has gotten considerably less, with some pockets there standing at somewhere between 50 and 75% of normal for the three months.
The rains we've had recently should help leave our temperatures at or a little under normal for the next couple of days, and humidity is down as well, but we look to be in for some heating later this weekend and next week, with more typical summertime hit and miss showers and storms returning.