National Hurricane Center Gives 50% Chance For East Coast Tropical Development

September 21 Thursday Mid Day Update

The weather system I have been reporting on all week got an upgrade this morning. The National Hurricane Center identified this circulation of of the Florida Coast as AL99. This ‘invest’ is trough with a cluster of thunderstorms with potential to develop into  a tropical or subtropical Low. At this time the odds have increased to 50% in the next two days. By that point this system will be moving very close or onshore in the Mid Atlantic region of the United States.

Water Vapor Satellite Loop

The broad circulation can be seen here. It iOS not well organized, but is trying. Regardless of if this gets formed or not, it will bring heavy tropical rain and strong winds this weekend.

Weather Advisories

As of Thursday Mid Day. Some may be upgraded as we get closer.

Gale Watch

Friday Evening To Saturday Night

• This includes the Northern Chesapeake Bay.
• Pooles Island to Sandy Point
• Winds 20 to 30 knots, Gusts to 40 knots
• Waves 2 to 4 Feet

Storm Watch

Friday Evening To Saturday Night

• Southern Chesapeake Bay and Coastal Waters
• Winds 25 to 35 knots, Gusts to 50 knots
• Waves Up to 5 Feet.

Storm Watch: Ocean Side

Friday to Sunday Morning

• Winds 30 to 40 knots, Gusts to 55 knots
• Waves Up To 14 Feet

Ocean Wave Model

Saturday Morning

Waves Over 10 Feet likely from Hatteras through Ocean City and coastal New Jersey.

Weather Maps

Even if this is not a named tropical system, it will behave like a very strong Nor’easter all weekend. The hardest impact will be on Saturday.

I will have an update this afternoon and again tonight.

Storm Update

I want to start off with the European ECMWF Model. This was the holdout, trying to bump it off the coast, as I showed in my report last night. Since then, the model has fallen in line with the rest to bring us the storm and keep it around all weekend.

Storm Animation: ECMWF Model Friday Morning to Sunday Night

Model Comparison: Saturday Afternoon

This looks like a lot more agreement for a Saturday Soaker. There is still a variation in storm position and track, but negligible to the general rainy expectations. The real difference will be in rain totals.

The net result will be rain and gusty winds, mostly from the Northeast, resulting in a chilly day remaining in the 60s.

Closer Look: Mid-Atlantic GFS Model

Since this has been the most consistent model, I am relying on it for the overall expectations.

Friday Night to Monday Morning

This covers our weekend and shows three main things:

1. The arrival of rain into Southern Maryland will be AFTER DARK on Friday,
2. Saturday will be rainy and windy!
3. Sunday once again has the storm stalling. The Ravens game looks chilly and wet!

Snapshots

Saturday Afternoon

Sunday Afternoon

With the remaining Low Pressure, a chilly north wind and leftover showers are expected for the Ravens game.

Wind Forecast

Animation: Friday Through Sunday

We can see the slow-moving circulation of the Low Pressure entering central Maryland. The winds FROM THE NORTH on the back side of the storm are what will keep us chilly with the rain.

Snapshot Saturday Afternoon

There may be water piling up on the Western Shore of the Bay, so look out for Coastal Flood Alerts in addition to Flood Advisories from the rain.

Sunday Afternoon

Less windy but chilly from the North.

Top Wind Gusts

There will be noticeable winds across the region. Central areas may gust to over 40 mph, with coastal areas possibly reaching over 50 mph.

Rainfall Potential

Considering that the European model had shown the storm as a miss, it is now in line with the GFS model to bring a few inches for most areas.

There will be LESS WEST and MORE EAST

GFS Model

European ECMWF Model

7 Day Forecast

Our Storm Day will be Saturday, but I have to increase our likelihood for it to linger with a chilly day and showers on Sunday. It will be chilly at the Ravens game!

Both afternoons will remain in the 60s. Remember, just last week, we had our record-breaking heat wave! This will be an adjustment.

EARLIER IN AUGUST: Maryland Trek 10 For These Kids

I will have a follow-up and recap on our amazing week shortly.

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RESTATING MY MESSAGE ABOUT DYSLEXIA

I am aware there are some spelling and grammar typos and occasional other glitches. I take responsibility for my mistakes and even the computer glitches I may miss. I have made a few public statements over the years, but if you are new here, you may have missed it: I have dyslexia and found out during my second year at Cornell University. It didn’t stop me from getting my meteorology degree and being the first to get the AMS CBM in the Baltimore/Washington region. One of my professors told me that I had made it that far without knowing and to not let it be a crutch going forward. That was Mark Wysocki, and he was absolutely correct! I do miss my mistakes in my own proofreading. The autocorrect spell check on my computer sometimes does an injustice to make it worse. I also can make mistakes in forecasting. No one is perfect at predicting the future. All of the maps and information are accurate. The ‘wordy’ stuff can get sticky.  There has been no editor who can check my work when I need it and have it ready to send out in a newsworthy timeline. Barbara Werner is a member of the web team that helps me maintain this site. She has taken it upon herself to edit typos when she is available. That could be AFTER you read this. I accept this and perhaps proves what you read is really from me… It’s part of my charm.

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