Today's Top Weather Stories
On Weather & Climate Through the Eyes of Mark Vogan
Historic East Coast Rainstorm Winding Down, Finally!
September can bring very wet weather, but why, Mark Vogan explains!
The Rain (and wind, in some areas) event that appears to be winding down over the East and has been extreme and historic, in fact one could dispute this event as one of the worst flooding set-ups on record for the Eastern US, however, it is that time of year when we can get very wet patterns in this part of the world..
Why here and why now?
Two things... 1) The Adancement of the season, colder air from the north drives troughs further south and is able to tap tropical moisture at near the peak heat of the year over these warm tropical basins. 2) Geography, it's key as to how the weather pattern evolves and indeed the positioning of where these very warm, tropical bodies of water are located, combine the two and this can be one of the wettest areas on earth at times!
Well, it's at that time of year when air masses to the north both grow and grow colder, therefore expanding and taking up more space. This is why we see the dips in the jet stream drop further and further south as September approaches October. Thus the colder air getting further south and into a much warmer and moisture rich environment creates an element of opposition within the atmosphere. When colder air dropped down with the trough over the heart of the US and ended the seemingly never-ending summer in the Southern Plains and Deep South, it forced both the formation of multiple low pressures on the tail of the front and base of the trough, the drop in the trough, brought these lows northwards, bringing with the lows moisture with the Gulf, Caribbean and Atlantic, ALL of these bodies of water within the tropics or certainly sub-tropics with warm currents running, adding fuelto the fire!
These circulations which pull down, increasingly colder air from the north on their backside, but injest and pull UP air straight from the still, very warm sub-tropics, guess what happens? It rains and rains a lot. The issue with this week's event was that not only did we see the formation of two "baroclinic lows" but also the development of Nicole which became of course a "fully tropical" closed area of low pressure, tracked north into the corridor already paved by the upper atmosphere with the trough over the US Plains and saw the progression north of these rain-bearing systems, fed and energized by both cold air to the north and warm, tropical air out of the south, which produced more rainsfall.. Indeed Nicole supposedly dissipated after forming over the mid-80 degree waters of the Caribbean Sea, at least of it's name anyway, but pushed north into a corridor already drenched by two low's which ultimately fed tropical moisture. All week, there has been a constant supply of tropical moisture rich air flowing directly northward from the Caribbean Sea to New England.
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Weather Talk
By Mark Vogan
coming later!
What's Reaching Today's Blogs?
Massive Flooding in East to Have Time to Recede, While Western Heat Gets Bounced
Joe Lundburg, AccuWeather
Today's Extremes here at my house
High: 57 degrees
Low: 51 degrees
TODAY'S COND
very heavy rain and strong winds (windier overnight in the western central belt, glasgow area), touching gale-force to the north and northeast of the central belt as this morning progressed, heavy weather eased during the PM hours, clearing and cooling off tonight and dropping into the 40s!
Thanks for reading.
-Mark
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