Some people have asked me if we will break the record for the driest July on record?
Some locations, including SeaTac Airport, have had no rain this month, and frankly there’s very little in the forecast for many locations.
First, how much rain has fallen so far? For western Washington, some places have gotten a bit, like the Cascades (from some thunderstorms last week) and along the coast.
Eastern Washington saw less rainfall, mostly due to a few showers from scattered thunderstorms last week.
Tomorrow, there could be some very light rain across the western part of the Northwest as a weak trough of low pressure moves up the coast. The latest forecasts suggest the air will be unstable enough for a few convective showers, especially over the Cascades and coast, but nothing major.
To illustrate, here is the latest cloud simulation from the UW WRF model as of 2pm tomorrow.
Looks impressive, right? You can tell it’s convective by the patchy look of the clouds. Lots of mid-cumulus.
But the rainfall is very modest….here are the forecast totals through 5am Monday. A few convective showers in southern Oregon, light rain along the coast, but very little inland.
The NOAA/NWS HRRR model is similar.
UW’s cumulative rainfall from this morning through the end of the month (below) predicts significant rain in coastal BC, but not much in much of the Northwest, except for the extreme southwest which receives some of the monsoon moisture from Arizona, Nevada and Utah.
The bottom line is that SeaTac and other places around here will most likely not get any rain in July.
Now comes the shock: This is not any kind of record. Several previous Julys have done the same.
To demonstrate this, here is July rainfall in SeaTac since about 1950. The previous six years had little to no rainfall. There seems to be a trend toward drier Julys, which is consistent with global warming simulations.
At least you don’t have to worry about bringing an umbrella. And with temperatures dropping, the weather is almost perfect for outdoor entertaining or a hearty barbecue.
