Currently: A warm front was arced in typical cold air damming fashion from Niagara Falls to near Wallops Island. This front will be the key to tomorrow's weather.
Tonight: Not too much change expected from where we are now regarding temperatures. The GFS guidance initialized 3-5 degrees too warm, so is basically discounted for tonight's forecast. Expect temperatures pretty close to 50 degrees statewide. Aside from some drizzle and fog, there is really no lift to produce significant precipitation tonight, so I will keep measurable precipitation out of the forecast.
Tomorrow: I may be taking a risk here, but when the forecasting gets tricky, sometimes it becomes necessary to do so. On days like tomorrow, where you're dealing with a sharp temperature gradient along a front, the "compromise solution" almost never works out, although it usually busts by the least amount of degrees. The NAM made a major cave to the GFS in the last run, by placing the front nearly 150 miles north of its previous run. The GFS has been steadfast in insisting that the front will plow through the state. I have sided with the significantly warmer GFS guidance for this reason. Expect high temperatures in the mid 70s. However, there still is the implied possibility that this forecast could be 10-15 degrees too warm. Precipitation chances tomorrow are dependent on the position of the front. If the front does in fact move through the state, there could very well be a line of showers and thunderstorms, some of which could be strong over interior sections, later in the day into the early evening.
Tomorrow Night/Friday: Models are coming into better agreement that the front will sag back south. The GFS had kept insisting that it would stay further north, but the latest GFS run has shifted well south. The newest GFS actually is a very good compromise between the NAM, which tends to push these things a bit too far south, and earlier, warmer model runs, so will generally follow. As for precipitation chances, there is ample lift for a some light rain, mainly during the morning hours. With a fairly good consensus that the front will be south of the region by then, there will not be any instability available for thunderstorms. High temperatures should be within a few degrees of 60, coolest along the south coast, due to onshore flow.
Long Term: Unfortunately, I do not have good news for the weekend, but don't shoot me, I'm only the meteorologist! Despite this, however, models have been slowing down with the overall progression of the frontal system and coastal low developing along the front for Saturday. In fact, models have now slowed down enough that we may be able to salvage a dry day Saturday, although it will still be generally cloudy and on the cooler side. As for Saturday's temperatures, with increasing clouds and a general onshore flow, I went a couple degrees cooler than the GFS-based long range guidance. Expect highs generally in the low 60s, again cooler along the south coast, with an onshore flow expected.
Sunday does not look nice at all. As a cold front stalls offshore, a coastal low, almost like a winter nor'easter will develop along the front. Waves of rain, heavy at times will dominate the forecast from Saturday night all the way through Sunday night. This could even become both a land-based flooding and coastal flood threat. Stay tuned! As for temperatures, I feel the GFS guidance, which is not atypical at this range, is significantly too warm. With a N-NE flow, heavy rain falling, and cool air aloft, I will shave 5-10 degrees off this guidance. I expect Sunday to be quite chilly, with daytime temperatures staying in the low 50s!
The rest of the long term, namely Monday through Wednesday, look to feature very nice weather. The next weather system does not look to impact the area until Thursday, and that is outside of our forecast period. GFS guidance does not look too far off for Monday or Wednesday, but appears a solid 5 degrees too warm for Tuesday, given the upper level temperatures and the general wind flow. Therefore, we'll be forecasting highs generally in the mid to upper 60s through that period.
The long range looks to feature more changeable weather, with a frontal system perhaps producing locally heavy rain every few days, not too atypical for the time of year. Some of the ensemble guidance wants to produce a big-time warm up in the 12+ day range. However, guidance often does this this time of year much like it produces Arctic outbreaks at that range in the winter. So until that gets inside the day 8-10 period, confidence in that actually happening is pretty low.
Now, let's take a look at a couple of systems slated to affect the area in the coming week. First, let's take a look at the frontal system slated for tomorrow. If you follow the wavy line that is the 1020 isobar, that's a pretty fair representation of where the warm front is located. You can see it is through the SW part of the state, and probably has a good 50 miles or so more to move NE before it is finished.