8-2016 Tropical like low on Gulf coast

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Pigeon
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8-2016 Tropical like low on Gulf coast

Post by Pigeon » Sun Aug 14, 2016 6:55 pm

A tropical depression-like storm with tropical depression-like impacts

The storm system responsible for the record rains formed a distinct surface low just inland along the Alabama coast on August 11, with a central pressure of 1013 mb.

By August 13, the low had drifted over northwest Louisiana, and intensified to a central pressure of 1007 mb. Like a tropical depression, the low had a warm core, and the counter-clockwise flow of air around the storm brought huge amounts of tropical moisture from the near record-warm waters of the Gulf of Mexico and northwest Atlantic northwards over land.

The amount of moisture in the atmosphere over the Gulf Coast region over the past week has been nothing short of phenomenal. Over multiple days, soundings of the atmosphere collected by weather balloon from locations such as New Orleans have measured record or near-record amounts of precipitable water (the amount of moisture in the atmosphere over a given point), often in the 2.5” to 2.75” range; sounding data extends back to 1948 in most cases. Sunday morning’s precipitable water of 2.61” in Lake Charles, LA, was among the top-ten values on record for that station.

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Pigeon
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Re: 8-2016 Tropical like low on Gulf coast

Post by Pigeon » Sun Aug 14, 2016 6:57 pm

Looks like a chance for a Cape Verde depression

African tropical wave may develop late this week

NHC was not highlighting any Atlantic tropical weather threat areas in their 5-day Tropical Weather Outlook on Sunday morning. However, two of our reliable models for predicting tropical cyclone genesis--the European and GFS models--showed that a strong tropical wave that moved off the coast of Africa on Saturday night does have the potential to develop into a tropical depression late this week as it moves west to west-northwest at 15 mph into the central Atlantic. In their 00Z Sunday runs, about 30 - 50% of the members of the European and GFS model ensemble forecasts predicted development of this system into a tropical depression late this week.

Working against development of this wave will be the fact that the Madden-Julian Oscillation (MJO), a pattern of increased thunderstorm activity near the Equator that moves around the globe in 30 - 60 days, is currently located in the Western Pacific. When the MJO is located there, we can expect to see increased typhoon activity in the Northwest Pacific, but compensating sinking air and surface high pressure over the tropical Atlantic, with reduced chances of tropical cyclone development there. Dry air from the Saharan Air Layer (SAL) will also likely interfere with Atlantic development this week, though the SAL is currently less prominent over the tropical Atlantic than it was early in August.


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Pigeon
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Re: 8-2016 Tropical like low on Gulf coast

Post by Pigeon » Sun Aug 14, 2016 6:58 pm

6.17 inches over rain overnight here, Aug 13-14.

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