Thursday Eve Update: There are already changes in the weekend forecast. The upper low is now expected to spawn a coastal low pressure system that forms over the Delmarva area and moves north on Saturday. Saturday that had been expected to be the drier day is not looking that way right now.
The latest NAM high resolution has rain starting in PHL as early as noon on Saturday, while the GFS holds it off until 4-5 PM. (earlier along the coast.)
Here’s the current High Resolution NAM forecast for Saturday afternoon—
This will be a complex system and the modeling of the upper low and its surface reflection often leads to inaccurate forecast placement of precipitation.
Either way, the next 6-7 days will be very unsettled with periods of heavy rains.
Wednesday Eve: An interesting weather scenario for July is shaping up for this weekend and next week.
An weak impulse will move from the Rockies and develop into a low pressure system near Ohio. With upper air support, this low pressure will transport warm, very humid and unstable air into our area by Saturday evening. A persistent threat of showers and thunderstorms will be with us from late Saturday through at least next Wednesday. High dew points will make it feel very warm, although significant hazy cloudiness may limit high temperatures.
Saturday will be the better day this weekend, with showers likely holding off until late in the afternoon or evening.
Sunday looks to be more unsettled with intermittent showers likely much of the afternoon.
As we saw last weekend, forecasts can change significantly. I’ll update Friday evening.
A chance of showers on Saturday has been advertised, and the GFS FV3GFS are somewhat pessimistic for Saturday’s weather.
However, I think the global models may be over-predicting showers and rain.
The NAM has been quite conservative regarding showers for Saturday and based on that model, I think just cloudy conditions for Saturday and mostly cloudy on Sunday is the most likely scenario. Certainly, a widely scattered shower is possible, but much of the day may be rain-free.
Thurs 10:30 pm update: Tonight’s NAM shows a lot more showers during the day Saturday than previous NAM model runs. So Saturday may be as unsettled and wet as forecast by the GFS. Stay tuned
An easterly wind will be responsible for the cloudiness. I’ll update Friday evening.
Fri Morning Update: The latest models have shifted the showers to late Saturday and most of Sunday into Sunday night. So Saturday is looking like a better day, especially from PHL and northward. I’ll do an updated weekend forecast Friday evening.
The weather for this weekend is again looking unsettled. There are huge differences between the NAM and GFS models for Saturday with the NAM being much wetter than the GFS.
Basically, there are timing differences with the disturbances that are expected to move along a frontal boundary. The position of the front is also in question.
Perhaps there’s insight in the fact that the new GFS model under development (referred to as the GFS FV3- “Finite Volume Cubed Sphere” ) has a similar forecast for Saturday as the NAM. By the way, I’ve been looking at the GFS FV3 more and more.
That would mean that Saturday would be the wettest and Sunday would be dry. Too soon to be sure.
This weekend’s weather is shaping up to be somewhat similar to last weekend’s Sunday-Monday forecast. Less than perfect weather for the start of June.
Low presssure developing near the Delmarva coast along with the moisture remnants of Tropical Storm Alberto will bring rainy conditions for much of Saturday. It will be warm and humid, with high temperatures in the low 80s. There may be some sun mid-day.
Like last weekend, high pressure will nose down from the northeast on Sunday suppressing rain to our south. An easterly flow will bring cool, mostly cloudy and damp conditions but much of the day Sunday will be rain-free. High temperatures 68.
Friday 11PM Update: Tonight’s NAM shows showers returning late morning on Sunday; Sunday doesn’t look dry as previously forecast .
There’s the chance of showers returning Sunday evening.