Serious Southeast Flood Threat Looms, Tropics Becoming More Active With Favourable MJO!

Written by on August 15, 2013 in United States of America with 0 Comments

The cold front which originally brought flooding rains and storms a couple of morning’s ago to the DC to New York corridor is now a stalled feature over the Southeast. This feature is triggering and will continue to trigger thunderstorms and heavy rains. Rain that is falling on already saturated ground of course and there appears to be little shift in this feature over the next 5+ days either. The real concern with this setup across this region is what is potentially looming down over the Western Caribbean. A low which is trying to form is seen by the models to push north into the Gulf and will pump far greater amounts of moisture up against the front, bringing a much more troublesome flash flood threat. Uniformly expect 3-6, locally 6-8 inches of rain from New Orleans up to Charleston, SC over the next 5-7 days.

Here is the projected rainfall totals according to the latest QPF chart for the next 7 days.


This is of course a very serious situation in what will likely be a top 5 wet summer right across the Southeast. Many cities will likely have seen their wettest summer on record and the next 7-14 days will likely help really raise those already high rain totals.

Here’s that system appearing to clip Southeast Louisiana and move inland around the Mobile Bay area Sunday.

Courtesy/Owned by AccuWeather Pro

Courtesy/Owned by AccuWeather Pro

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As for the tropics overall, it’s about to get more and more active as conditions improve. We loose a lot of the dry air that’s been really keeping a lid on things along with shear over the last month and the MJO pulse is now entering a much more favourable 1, 2 and 3 phase.

As you can see from the below MJO chart off the ECMWF, it’s trying to bring it into the most favourable phase over the next few weeks.


The GFS ensemble agrees!


As you can see the greens appearing over the Atlantic which indicates an INCREASE in convection as pressures lower and with lesser amounts of Africa dust and shear, we need to take what’s coming off of Africa much more seriously.


MJO Phases Favour Warmer Times Again For The Midwest And East Next Couple Of Weeks

As for temperatures across the Lower 48, while very comfortable across the Northeast and Mid-Atlantic, is going to be cool even across the Southeast and not just because of the cloud and rain but because the high building down over the Mid-Atlantic will draw cooler air underneath, around the high, funnelling that cooler NE flow around the mountains which gets trapped in the lower atmosphere. This pegs daytime temperatures to the low and mid 70s in the coming days across Alabama, Georgia and the Carolinas.

However, as the MJO enters a the more conducive phases in terms of the tropics, it’s also entering phases which bring heat back to the Midwest and East next week into the following week.

As you can see from the below charts, the phases we’re entering a warm phases in the Midwest and East.


The return of warmer back into the East is also backed up with the NAO too (positive) next few weeks.


Here’s the ECMWF upper chart/850 temps for next Thursday. We’re likely to see 90 back into Chicago, Pittsburgh and the Big Cities of the I-95!


Hope to get a video up for you tomorrow…

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