Wednesday, 9 March 2016

Extreme weater for Mississipi valley

Mangled Jet Stream, River of Moisture Set to Deliver Extreme Flooding to Mississippi Valley

8 March, 2016

The potential rainfall totals for a broad region centering just west of the Mississippi River Valley are absolutely extraordinary. For even a strong spring storm, this event may hit unprecedented levels. It’s the kind of abnormal event we’ve now come to expect in a world driven 1 C + warmer than 1880s levels by a merciless burning of fossil fuels that just won’t quit.
Mangled Jet Stream Aims River of Moisture at Central US and Gulf Coasts

Over the past few weeks, a record warm El Nino has been slowly cooling down in the Equatorial Pacific. One of the top three strongest events on record, this particular warming of sea surfaces in the Pacific coincided with never before seen global heat as atmospheric CO2 levels spiked to above 405 parts per million on some days during February and March. The record warm sea surface and atmosphere held a never before seen excess of water vapor and moisture in suspension — primarily over the Equatorial Ocean zones. And as the world hit peak temperatures during early March and began to back off a little, some of that massive excess of moisture was bound to wring out somewhere.

For such events, all you really need is a trigger. And over the past two days, forecast models have been predicting an insane dip in the Jet Stream. Today, we got it. A raging storm track over the Northeast Pacific roared its 200+ mph upper level winds down over the Western US and Mexico. It drew deep from a rich, record global warming intensified, low Latitude moisture flood as its tail end reached all the way to the Equator itself. This insanely deep trough then turned north, aiming an unprecedented atmospheric moisture flood fire-hose style at the storm-tossed airs above the Mississippi River Valley.

Huge Dip in the Jet Stream March 8
(An extreme dip in the Jet Stream stretching through the Western US and all the way to the Equator is aiming both Pacific and Gulf moisture at the Mississippi River Valley today. The severe storms that are now firing and that are predicted to continue over the next three days may result in an unprecedented flooding event. Image source: Earth Nullschool.)

Foot of Rain or More over Mississippi River Valley in the Next Three Days

Rain that is expected to be extraordinarily intense and long lasting. Reports from the Weather Channel indicated the risk for rainfall rates in the range of 3 inches an hour in some of the heaviest storm cells. Meanwhile, model runs earlier today indicated a potential for as much as 20 Inches of rain for some regions over the next 72 hours. Official NOAA models are now indicating nearly a foot in peak rainfall regions in Eastern Texas and Western Louisiana with the potential for greater than five inches along a broad swath running from the Gulf Coast through to Illinois.
72 Hour rainfall totals NOAA NCEP
(NOAA predicts very extreme rainfall totals over a broad region of the Mississippi River Valley during the next three days. Image source: NOAA’s Weather Prediction Center.)

According to NBC news reports, more than 15 million Americans are falling under risk of flooding from this very severe weather system. One that has been compared with the South Carolina floods of 2015 due to its potential to produce severe rains. But one that is also much wider in coverage — capable of impacts over a far broader region.

In addition, those flooding rains will fall all over the Mississippi River Valley — resulting in an extreme threat of very severe flooding all along this great river and its tributaries. As such, we are likely to be dealing with a flood situation for many days after the initial rain event tapers off. With Spring on the way, with so much moisture still bleeding off the Pacific, with a record level of global warming greatly amping up the hydrological cycle, and with a trough development tendency setting up for this region — this particular extreme rainfall event may, sadly, be but the first of many this season.
Hat Tip to DT Lange
Hat Tip to Anthony Sagliani

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