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95L organizing off coast of Africa; Pakistan's Indus River flood crest nears coast

By: Dr. Jeff Masters, 3:35 PM GMT on August 20, 2010

A tropical wave in the far eastern Atlantic about 300 miles southwest of the Cape Verdes Islands was designated Invest 95L by NHC this morning. Satellite loops show that the wave has some rotation, and heavy thunderstorm activity is starting to build. The wave is in a moist environment over SSTs that are at near record warmth (28°C). The main impediment to development is the moderate 10 - 20 knots of wind shear over the system. As 95L moves away from Africa, wind shear will decrease, and system will probably develop into a tropical depression by Sunday or Monday. NHC is giving 95L a 40% chance of developing into a tropical depression by Sunday morning.

Figure 1. Morning satellite image of the disturbed region of weather of the coast of Africa, south of the Cape Verdes Islands.

Forecast for 95L
A ridge of high pressure will force 95L to the west or west-northwest for the next five days, and the system should increase its forward speed from its current 5 - 10 mph to 15 - 20 mph by Monday. A series of two powerful troughs of low pressure are predicted to move off the U.S. East Coast next week and cross the Atlantic; these troughs should be able to pull 95L far enough to the northwest so that it will miss the Lesser Antilles Islands. The long term steering current forecast from the GFS model indicates an above-average chance of recurvature of storms approaching the U.S. East Coast through the end of August, followed by a near-average chance of recurvature for the first week of September.

Elsewhere in the tropics
A tropical wave in the western Caribbean approaching Mexico's Yucatan Peninsula is generating disorganized thunderstorms, and the wave does not have enough time over water to develop into a tropical depression before moving ashore tonight or Saturday.

The ECMWF model is predicting formation of a another tropical depression of the coast of Africa seven days from now. The GFS model predicts a possible subtropical depression may form off the coast of Virginia 5 - 6 days from now and move northeast towards New England.

Pakistan's monsoon rains ease; Indus river flood crest nears the coast
The flooding on Pakistan's largest river, the Indus, has slowly eased along the upper and middle stretches where most of the heavy monsoon rains fell in late July and early August. However, a pulse of flood waters from these heavy rains is headed southwards towards the coast, and flood heights have risen today close to the all-time record for the Indus River gauge station nearest to the coast, Kotri (Figure 2.) Flood heights at nearly every monitoring station along the Indus have set all-time records this month (records go back to 1947.) Fortunately, the monsoon has entered a quiet phase. Little rain is expected over Pakistan over the next 3 - 4 days, according to the Pakistan Meteorological Department.

Figure 2. Flood heights along Pakistan's Indus River during August, 2010. Heavy rains during late July and early August brought record flood height to the upper and middle stretches of the river earlier this month; a wave of flooding progressed downstream, and has now arrived at the monitoring station closest to the coast, Kotri. Image credit: Pakistan Meteorological Department.

The writer of our Climate Change blog, Dr. Ricky Rood, has a sister working in Pakistan, and he is very conversant with the situation there. In his post this week, Pakistan: A Climate Disaster Cast Study, Ricky writes, "We have, here, harsh, brutish reality - a fragile, geopolitically important country where lives, crops, and infrastructure have been washed away. A public health nightmare will follow. We have here a case study of a climate disaster. " In the words of Molly Kinder, a senior policy analyst at the Center for Global Development, who is leading the center's work on a U.S. development strategy for Pakistan, providing aid to Pakistan it is a moral imperative, a humanitarian imperative, and a security imperative.

Figure 3. Image of the Pakistan flood catastrophe of 2010, courtesy of the Pakistan Meteorology Department.

Here are some places that Ricky's sister, Elizabeth, has recommended for donations to help out in the humanitarian crisis in Pakistan:

Doctors Without Borders

The International Red Cross

MERLIN medical relief charity

The mobile giving service mGive allows one to text the word "SWAT" to 50555. The text will result in a $10 donation to the UN Refugee Agency (UNHCR) Pakistan Flood Relief Effort.

Jeff Masters

Flood Hurricane

The views of the author are his/her own and do not necessarily represent the position of The Weather Company or its parent, IBM.