September 06th, 2018

Changes,, andt more of the same.

That is a good summary for the next 7 days. The changes include the ending of this hot spell, and the entrance of a possible impact from a hurricane. More of the same include potential for heavy rain, and the presence of more humid weather. Let’s take it one at a time.

1. Hot Spell Ending:  It will end with some heavy showers and thunderstorms late this afternoon/evening.
2. More Humid Weather: Friday will be cooler, but it will still be humid. We will get a break from the humidity on Sat/Sun but it will return for Monday.  
3. Heavy Rain: Today and Fri with the showers/storms. Possibly Sun night and Mon with the remnants of Gordon.
4. Hurricane Florence:  It is likely to threaten the east coast, but how far west it comes is a big question for several reasons:
   1. Exact hurricane track forecasting is very poor beyond 3 days.
   2. Models often understate the strength of ridges supported by warm ocean temperatures, and love to knock them down too fast.
   3. Major hurricanes can help support the western extent of a ridge and help push itself further west. This can happen, has happened, but does not mean it will happen.

Before we jump on that “hype train” we have some weather to contend with: (Rant: saw a post by one meteorologist complaining about “overhyping weather” when 4 hours earlier he posted a screen shot of a video he did with the most extreme model forecast of Florence sitting just off the NJ coast pounding the region. Maybe he was complaining about himself … )  

The storms that occur today/this evening will produce some very heavy rain, and will be slow moving, as the front will be stalling out. This could produce some localized flash flooding issues in the areas that get hit the hardest. I would expect on average .5” – 1” rain for most, but much more in those isolated areas. More rain is likely Fri and it too could be heavy and slow moving. Another .5” is possible for most.

Saturday and Sunday appear dry for the most part but areas of low clouds and fog on the ridges with some drizzle is possible, esp. early in the day.

Next issue is the remnants of Gordon. The good news is that the bulk of the rain will remain to our NW as the steadiest and heaviest rain moves from the Ohio Valley to the St Lawrence Valley. NW half of PA will be impacted with this steady heavy rain. The further NW, the more rain one will receive. But I am concerned about being on the SE side of a system with tropical or partial tropical origins. Thunderstorms are notorious for firing at night in tropical airmasses and the SE side is the region it usually occurs. Could they do so and impact us Sun night/early Monday? 

One element that may prevent this is the fact that we will be cool/stable air dammed Sun night until the warm front lifts north on Monday.

We will know more in a couple of days regarding Gordon remnants and Florence. Until then, enjoy.