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Atlantic Coast: Massive Rainfall Explained

9 Oct 2013, 11:34 am

We’ve got heavy rain in the East, and heavy snow falling in the Mountain West.

 

Tahoe Snow
Tahoe Snow

 

Look at that!

Snow keeps sneaking farther south, of late, and that trend looks to bring snowfall into the mountains east of Los Angeles and San Diego.

 

Winter Weather Advisories
Winter Weather Advisories

 

While most snow will be at or above about 6000 feet, it’s still always interesting to see every region’s first snowfall of the season!

The interesting thing about this particular storm, outside of the snow it’s bringing to places (Winter Storm warnings/watches over some popular Colorado ski destinations as well), is that it looks to grow as it moves into the Midwest toward the end of the week.

We’ve got winds, thunderstorms, and lots of moisture on the way for the Midwest by the end of the weekend.  That rainfall will look to wrap northward and into Canada over the weekend – with only some falling over the Midwest & Great Plains.

 

Rain Through Monday
Rain Through Monday

 

The obvious portion is where the numbers are showing 3″+ rainfall over the Mid-Atlantic, which I strategically placed for this image to provide a segway into the Mid-Atlantic section of this blog… but in the meantime we’re still talking about the other rainfall – those blobs you see over the Midwest and the South.

Let’s move to the Mid-Atlantic now (nice segway, huh?).

The big question I’ve been hearing is “Why is there this nagging system over the Mid-Atlantic?”

Well, let’s take a moment to answer that – look at this graphic below closely, and I’ll go more into detail about what I’m actually talking about with it:

 

Coastal Low Explained
Coastal Low Explained

 

Many people have been referring to the “ghost of Karen” – referencing the remnants of what was once tropical storm Karen – and I am loving that term.  It sounds like a campy 1980s movie.  However, the wave of energy associated with that has helped to enhance the growth of this low.  It’s become slightly more progressive, in a northerly direction, which has brought much more rain to the forecasts for New York, New Jersey, etc.

Also of note is the “split flow” term for the jetstream.  If you live in Minneapolis, Chicago, St. Louis, or any other spot that would typically be a little cooler, but you aren’t experiencing “extreme” heat – you can thank that split flow pattern.  Temperatures have generally been in the 70s for all of these spots.  Above average, but well below records.

 

5 Day Precip Outlook
5 Day Precip Outlook

 

The unfortunate aspect of the coastal low we’re discussing, that is stalled on the eastern jet of the split flow pattern, is that it isn’t moving much.

This is where it looks to move, as per the GFS computer model, between today and Friday:

 

Coastal Low
Coastal Low

 

Not a lot of movement.

Stay tuned!  We’ll have more over the next couple of days, until this thing clears away!

WeatherNation Meteorologist Aaron Shaffer @ashafferWNTV

 

 

 

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