Saturday, July 28, 2012

Tropics Quiet; Disturbance Moving Off Africa

Regional Satellite Analysis

Surface Analysis
The tropics are fairly quiet this evening, with no large areas of convection across the board, other than a cluster moving off Africa, which will be discussed later.

The Caribbean is quiet at the moment. Surface analysis indicates two tropical waves moving into the region, but neither are posing substantial shower and thunderstorm activity and thus are not favored for any development in the next while.

Gulf of Mexico
Showers and thunderstorms are propagating on the Gulf coast, but little significant storm activity exists in the Gulf of Mexico. These coastal showers and storms are fueled by the presence of a pair of troughs in the region, feeding off the humidity and warm air to produce showers and thunderstorms.

Eastern Atlantic
There is a disturbance moving off of Africa and is producing a large region of showers and storms. Surface analysis shows these storms developing along the monsoonal trough and in the presence of a low pressure area. Shearing, shown below, indicates that significant development in the next day or two does not seem too likely.

Shearing in mid levels


Images obtained from:
-Shearing image: CIMSS
-Surface Analysis: OPC
-Regional Satellite: NHC

Severe Weather Threat May Accompany Early August Disturbance

The 12z ECMWF is projecting a disturbance to move southward and slip into the Upper Midwest in early August, similar to that of the system that produced several damaging bowing segments over the Upper Midwest, Great Lakes and Northeast over the past several days.

What happened then and is forecast to happen in early August have very similar features, as seen below in this chart of the weather pattern on July 23.

On July 23, there was a low pressure system in the Upper Midwest with trailing cold front, with a ridge of high pressure extended from the Southeast out into the Plains. If we compare this map to the ECMWF forecast, it does become apparent that these systems are very similar. A key difference in any possible resulting thunderstorm track is the lack of a ridge in the Southeast. One was observed on July 23, which was the day of the derecho in the Ohio Valley. However, now, with the lack of a ridge, we could see the progression of possible storms more into the Ohio Valley. Also of potential is that the system could move east and the storms would deflect into the Northeast. Time will tell, and the models should align soon.


Drought Worsens Across Nation; Outlook Miserable

The latest drought monitor update on July 24 cites an increasing and worsening drought across the nation, with Extreme to Exceptional drought conditions most prevalent across the Plains and Midwest.
With this latest update, the hope for help for agricultural products dims further, and it is likely that entire sectors of the agricultural business may be a total loss.
Now, we look from the short term corn crop concern to the question of 'How long will this last?' I can tell you that it will take months to regulate this deficit.

This map shows the precipitation needed for the drought to end. But, before we analyze it, there are some caveats. First and foremost, the needed precipitation must fall over a prolonged period of time. If it happens to fall all at once, only a small fraction of help will be delivered, while the rest of the rain will run off the dry ground and produce flash flooding.
The areas needing most precipitation (on the order of over 15 inches of rain) includes the Southern Plains into portions of the Midwest. This is typical of an El Nino pattern, with a possible expanse eastward and further deterioration of soil conditions.

I am predicting this drought to continue for months to come, into 2013. Considering we are entering an El Nino, I find the Plains and Midwest to be between a rock and a hard place, with El Ninos typically delivering below normal precipitation to the mentioned areas.
If you are a farmer based in the Midwest, I must say that the next 4-8 months (or beyond if the pattern holds) are looking miserable for agricultural crop harvests and/or plantings.