Rainy, unsettled pattern likely to continue into late May. Here's the reason why.

We are not even halfway through the month of May and already Washington, D.C. is quickly approaching its monthly average total for rainfall. Through Mother's Day, 3.10 inches of rain had fallen already at Reagan National Airport which puts us less than one inch away from the monthly average of 3.99 inches. Going back to the start of 2018, only four of the 16 completed months have seen below average precipitation. 2018 was also a record shattering year for precipitation, with 66.28 inches of rain falling over the course of the year. This broke a long standing 130-year-old record of 61.33 inches of rain from 1889. Shockingly, we are currently keeping pretty good pace with last year here, with 16.16 inches of rain so far through 2019.

The question is are we ever going to get a break from this pattern, in particular, the one that seems to have brought us rain every single weekend over the past several weeks? The answer is both yes and no. In the short term, there does seem to be a little relief from the soggy pattern building. Much of the middle of this week looks dry, and as things stand at this moment. Even the weekend looks like it has a pretty good shot at being on the dry side. However, the extended picture heading into the latter half of the month is not necessarily foreboding a trend towards a drier overall pattern.

As is typical of weather patterns in general, the weather where you live is typically due to things going on in the atmosphere -- often times thousands of miles away. Our issue here, and across much of the eastern half of the United States, are features known as high latitude blocking that are set up across the northern polar regions. Specifically, features we call the Arctic Oscillation and North Atlantic Oscillation.

What are they exactly? Well in an oversimplified way, think of them as road blocks in the upper atmosphere. Weather features like storms cannot get through them, so they have to go around them. In addition, depending on their strength and exact location, they will buckle the Jetstream, the upper level zone of high winds that weather systems like to ride along. Currently, these features are forcing the Jetstream south across the northeastern United States, leading to the cool and damp conditions we are currently experiencing.

These features are not stagnate. The Jetstream will jump north then back south again as these upper blocks vary in strength and exact location. When this happens we will typically see periods of several days of sunny and dry weather return to the region, much like what is expected during the middle of this week. However, as long as the blocks remain present across the Northern Hemisphere, the threat for the forecast to return to a gloomy and showery state will remain. Typically, these blocks like to cycle in four to six week increments. Current extended range guidance suggests some softening of these blocks by the end of May. We will keep our fingers crossed that with the first big beach holiday weekend of 2019 approaching, we can finally turn the corner towards a drier pattern in the weeks ahead.