Excessive Rain Outlook Timeline Wednesday And Thursday

November 10 2020

Over the last seven days, Baltimore has reached the 70s every day and set two record high temperatures. That included today with a high of 78ºF, nearly 20 degrees above normal. That is about to end with some heavy rain over the next two days.

The rain will arrive later Wednesday morning, then bring heavy bands and some potential thunder. It will be an abrupt change Wednesday and Thursday.

Excessive Rain Outlook

Our region has the potential for flooding.  The Slight Risk here is for rainfall that could reach into the 2 to 4 inch range.

Below is a look at the rain timeline and three different computer model rainfall forecasts.

 

 

Tuesday Evening Weather Set Up

The combination of a cold front and moisture well ahead of Tropical Storm Eta will team up to send a lot of moisture our way.

Note: Tropical Storm Eta has 60 mph winds and is closer to Cuba than the US for now. It will drift north, but we are not getting the storm itself.  For the purpose of this post, I am only showing our rain. I will update the storm details in my next report.

 

Rain Timeline(s)

Radar Simulation Wednesday —> slider

 

 

 

Radar Simulation Thursday —> slider

 

 

 

How Much Rain?

Let’s compare this NAM 3 Km Model to the GFS and ECWMF below.

NAM 3 Km

This shows the highest rain totals, and is often a little overblown. It is likely to be a little too high this time as well.

 

GFS Model

This seems a little more realistic. A general 1 to 2 inches of rain, with higher spots in central Maryland.

Higher amounts are likely in southern Maryland and on Delmarva.

 

European Model

This is the lowest of the three model outputs. This is similar in layout to the GFS, with the most rain across southern Maryland and Delmarva.

 

 

My Take Away:

The regional threshold for flooding would be in the 2 to 3 inch range.  However, we could also have some downpours with storm drains clogged with leaves.  So some isolated flooding is possible with less total rain, but quick bursts.

The entire event will be ending during Thursday.  So there will be improvement to end the work week, but it will no be as warm.

 

 

Forecast Snapshot

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