Odd/Rare Midsummer Nor’easter This Weekend

I had someone comment to me yesterday that we’ve had a lot of weird weather lately, and mother nature heard that and said “hold my beer.” A rare Mid-summer Nor’easter will affect the eastern US over the next 2-3 days with torrential rainfall, wind, and temperatures 15 – 25 degrees below normal. I’ve been watching this for several days now, and first introduced the unsettled pattern coming last weekend, and things really haven’t changed.  So let’s take a look at what’s going on.

First, all of Maryland, and much of the surrounding area is under a FLASH FLOOD WATCH for Friday afternoon to Saturday afternoon. If you have to go out, remember, if you see a flooded roadway, turn around, don’t drown. Don’t end up on the news 🙂

Rainfall amounts of over 2″ widespread present serious flood concerns this weekend.

The animation below shows the upper level evolution of the system. The jet stream carves out an unusually deep (for summer) trough over the eastern US as a strong piece of energy embedded within the trough drops southeast over the Mid-Atlantic. This is basically the summer time version of a winter storm or nor’easter forming.

At the surface, the above upper level setup will kick off a surface area of low pressure over the lower Midwest and will track east, across our area, then develop as a coastal low before moving northeast up the coast. The track of the low is important, as the heaviest rainfall, and therefore, greatest rain amounts will fall just north of the low track.

All of this creates ideal conditions for a rare, mid-summer nor’easter to bring rounds of very heavy rainfall to the area, flooding, wind, coastal flooding and possible beach erosion, and temperatures on Saturday that will be 20-30 degrees below normal!

Here’s a break down of the forecast…

Period of heavy rain will bring 2-4 inches of rain widespread. Some spots could see higher than that (some models have localized 6+”), but pinpointing that is impossible.

Saturday is the day I’m concerned about. The heavy rain threat will be diminishing, but the winds will really kick up. Power outages, coastal flooding/erosion are possible.

Winds on Coast could gust over 40MPH. Coastal flooding and beach erosion on the western shores is possible.

 

And finally, here’s what a few of the models are saying for rainfall. Remember, it’s only one run of one model, so don’t take specifics seriously-but the general idea.

GFS MODEL

2.5-4″ of rain.

 

High Resolution NAM Model

2″-4″, locally up to 7″ Note: model has a wet bias (tends to have too much precip)

 

Short Range Ensemble Forecast (SREF) model

2-6″ of rain
SREF is a collection of 26 individual models run & averaged together

 

The European model has 2″-8″ of rain across the area. Restrictions on the Euro model disallow me from sharing a map.

That’s the latest, and I’ll continue to keep you updated through the weekend on the Facebook page.

-Andrew