I am sure that like me, you all have become quite sick of our streak of rain filled weekends. However, my disdain for our wet weekends goes beyond the typical complaints one might have. Namely, forecasting for these weekends has been quite difficult! Since I am sure you are all extremely sympathetic to my plight, I will give some more details below on why these forecasts have been difficult. As for the sensible weather details for the near term, my one primary piece of advice would be to dress and accessorize for rain if you plan to venture outside tonight or tomorrow.

Get our daily forecasts on your Amazon Alexa device. Click here to find out how.

Through Tonight: The forecast for this evening is very location dependent. Generally, areas south of I-66 as well as areas along and east of I-95 are most likely to see pop-up storms over the next several hours. Luckily, these storms aren’t moving as slowly as some of the recent storms we’ve experienced, so a widespread flash food threat is somewhat neutralized tonight. However, localized flash flooding is still very much in play. Any storms that pop up this afternoon run the risk of becoming severe, featuring heavy rain, thunder, lightning and small hail. Certain areas may be hit with 2 or more pop-up storms in the afternoon, which means a copious amount of rain may fall in a short time over the same area.

All of that said, the rest of us will see partial sunshine as we duck in and out of clouds for the rest of the day. Folks to the north and west of D.C area are not immune to some scattered storms developing late this afternoon, especially in areas with elevated terrain. All storm activity should begin to wane after sunset. Overnight, we are mostly cloudy with a chance at some additional scattered storms developing in the early morning hours. Staying warm and humid, with lows and dew point values in the upper 60s. Some patchy fog is likely to develop before daybreak.

View the current weather at The Washington Post.

Tomorrow (Sunday): I am thinking that Sunday will start out dry for most of us, and stay that way at least through the early afternoon. How warm we get will depend on if we can burn off the early morning fog and low cloud cover. As of now, I think we will have a hard time breaking through the clouds at any point tomorrow, so highs are likely to be in the upper 70s with dew points in the upper 60s to low 70s. The chance of storms and rain increases by the mid to late afternoon. There won’t be as much of a severe weather threat with tomorrow’s storms, but precipitation coverage is likely to be more widespread. In fact, I expect most of us will get wet at some point tomorrow. Flash flood concerns will be elevated once again, as tomorrows pocket of heavy rain will be moving slower than today’s storms. Mostly cloudy but a bit cooler tomorrow night, with lows in the mid 60s.

See Ian Livingston’s forecast through next week. And if you haven’t already, join us on Facebook and follow us on Twitter and Instagram. For related traffic news, check out Gridlock.

Why such forecasting troubles? Meteorologists like boundaries. That is, we like it when there is a well defined cold front or storm center that we can identify on a surface map. Having a defined boundary gives a forecaster a “control” variable if you will, armed with the knowledge that interesting weather tends to occur in bunches around said boundaries.

But today, we’ve got two problems.

  • There is no real distinguishable frontal boundary to speak of. Frontal positions are usually identified by a sharp change in wind direction, temperature or humidity. But looking at local surface observations, it’s very hard to determine where that sharp change exists. Basically, it means that we don’t have a good idea where the surface front actually is.
  • Which leads us to problem No. 2. Weather model accuracy relies quite heavily on an accurate “snapshot” of the atmosphere. If we don’t know where the front is, how are we to know where it will be in three hours?

And as I was writing this, I actually thought of a third problem.

  • Since our surface front is being shy, it’s not dominating and focusing the weather around it like a front typically should. That means a lot of other localized atmospheric influences have a chance to step in and mess things up. One of those influences is the sea breeze that develops on a daily basis because of temperature differences between the ocean and land. The sea breeze suddenly acts as a boundary area where a lot of low level moisture converges. That’s one of the reasons we are seeing such heavy rain east of D.C. and toward the Eastern Shore.

So there you have it, a complete and thorough explanation on why I can’t be held responsible for an incorrect forecast today!

Want our 5 a.m. forecast delivered to your email inbox? Subscribe here.