Dora weakens to a tropical storm, another East Pacific system, Chance of Atlantic MDR development decreasing

Dora weakens to a tropical storm, another East Pacific system, Chance of Atlantic MDR development decreasing

Tropical Storm Dora is feeling the effects of cooler sea surface temperatures, and has begun to weaken. Dora fell below hurricane strength this afternoon as deep convection has continued to decrease. Dora should continue to lose convection and become a remnant low by Thursday, if not sooner. Meanwhile, two other systems (one in the Atlantic and one in the East Pacific) both have a low chance of development over the next several days.

Dora meeting its demise

Rainbow loop of weakening Tropical Storm Dora over the Eastern Pacific. (Source: NOAA)

This morning, Dora still had a well-defined eye structure. However, this afternoon, deep convection has essentially vanished on Dora’s west side. The only remaining deep convection with Dora is in a small area to the east of the center, where waters are slightly warmer than on the west side. At 3:00 p.m. MDT (5:00 p.m. EDT), Dora was centered near 19.6°N 111.4°W, and was moving to the west-northwest at about 13 mph. Maximum sustained winds were estimated to be 55 knots (65 mph) with an estimated minimum pressure of 995 mb. This intensity of 55 knots is based on a blend of ASCAT data and Dvorak estimates, but could be a little generous based on the recent loss of deep convection. Dora’s demise is being slowed by light wind shear. Sea surface temperatures around Dora are currently near 24°C (75°F), and should only decrease during the next few days as Dora moves to the west-northwest. Dora should be devoid of deep convection by Thursday, perhaps even as soon as tomorrow. Dora is no longer a threat to any land areas.

NHC monitoring an area in both the Atlantic and East Pacific – not very likely to develop

Official Tropical Weather Outlook for the Atlantic for June 27, 2017, 8:00 PM EDT. (Source: National Hurricane Center)

The National Hurricane Center (NHC) is currently monitoring two areas of interest, one in the Atlantic and one in the East Pacific. In the Atlantic, a tropical wave is expected to emerge off the African coast tomorrow or Thursday. The NHC gives this wave a near zero percent chance of development within 48 hours and a 10 percent chance within five days, down from 20 percent earlier today. Models have largely dropped development of this wave, and with an unfavorable environment and climatology not favoring development, development of this tropical wave south of Cape Verde seems very unlikely at this time. Prior to today’s 18z run, several GEFS ensemble members were suggesting that development of this wave could occur near the Lesser Antilles, but the 18z ensembles have backed off the idea.

In the East Pacific, an area of low pressure is expected to develop later this week, and could develop into a tropical cyclone as it moves to the west-northwest. Model support remains weak for this system, and none of the most recent GFS, ECMWF and CMC runs predict development of this system during the next five days. The NHC gives this system a near zero percent chance of development within 48 hours, and a 30 percent chance of development within five days. Based on the lack of model support, I think the 30 percent chance within five days is too high, and I only give this system a 20 percent chance of developing within the next five days.

I now give only a 10 percent chance that we will see Tropical Storm Don form over the next 10 days, and a 40 percent chance that we will see Tropical Storm Eugene form over the next 10 days. I will be back tomorrow for another post on these possible systems, which do not appear very likely to develop in the near future.

 

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