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Gulf of Mexico's 93L a Heavy Rain Threat; 92L Kills 5 in Canary Islands

By: Dr. Jeff Masters, 3:29 PM GMT on October 20, 2014

Moisture from Tropical Storm Trudy, which made landfall on the Pacific coast of Mexico about 75 miles east-southeast of Acapulco on Saturday morning, has moved northwards across Mexico into the southern Gulf of Mexico's Bay of Campeche. A large area of low pressure (93L) is forming there, and will bring heavy rains to Mexico's Yucatan Peninsula, Western Cuba, and South Florida on Wednesday through Friday. Satellite loops show the low has plenty of heavy thunderstorm activity, but these thunderstorms are poorly organized, due to high wind shear of 30 knots. Water vapor satellite images show there is dry air from Mexico flowing eastwards over the central Gulf of Mexico, which may slow development. Sea Surface Temperatures (SSTs) are very warm, about 29.5°C. The 8 am EDT Monday run of the SHIPS model predicted that wind shear would fall to the moderate range, 10 - 20 knots, Wednesday - Friday, giving 93L a better chance to develop in the later part of the week. The Monday morning runs of our three reliable models for predicting tropical cyclone genesis, the European, GFS and UKMET models, all showed support for some slow development of 93L this week. In their 8 am EDT Monday Tropical Weather Outlook, NHC gave 93L 2-day and 5-day development odds of 30% and 40%, respectively. The low should move generally eastward or east-northeastward during the week, spreading heavy rains, with rainfall amounts of 4 - 8" likely over Mexico's Yucatan Peninsula, Western Cuba, and South Florida.

Figure 1. Latest satellite image of Invest 93L in the Gulf of Mexico.

Figure 2. Predicted precipitation for the 7-day period ending Monday, October 27, 2014. 93L is predicted to bring rainfall amounts of 4 -8 inches to South Florida. Image credit: National Weather Service.

Flooding from 92L kills five in the Canary Islands
A large non-tropical low pressure system spinning in the Eastern Atlantic between the Canary Islands and Azores Islands (92L) brought heavy rains and flash flooding that killed five people in the Canary Islands on Sunday. At Santa Cruz in the islands, 5.35" (136 mm) of rain fell in just six hours. This low is headed slowly westwards, and should not affect any more land areas. The 8 am EDT Monday run of the SHIPS model predicted that wind shear would be moderate this week over 92L, 15 - 20 knots, but ocean temperatures would be quite cool, around 23°C (73°F.) These conditions are marginally favorable for formation of a subtropical storm, and in their 8 am EDT Tropical Weather Outlook, NHC gave 2-day and 5-day development odds of 10% and 30%, respectively.

Video 1. Torrential rains in the Canary Islands caused flash flooding that killed five people on Sunday, October 19, 2014.

Ex-Gonzalo to bring high winds to the U.K. on Tuesday
Hurricane Gonzalo transitioned to a powerful extratropical storm with hurricane-force winds on Sunday afternoon after speeding by southeast Newfoundland, Canada on Sunday morning as a Category 1 hurricane with 85 mph winds. Cape Race, Newfoundland measured sustained winds of 41 mph, gusting to 55 mph at 8:30 am local time as Gonzalo moved past. Gonzalo hit Bermuda near 8:30 pm EDT Friday night as a strong Category 2 storm with sustained 110 mph winds, causing moderate damage but no loss of life. On Tuesday, the powerful extratropical storm that was Gonzalo will hit the U.K., bringing wind gusts of 50 - 80 mph. The UK Met Office has posted a "Yellow warning of wind" for the islands for Tuesday, with the highest wind gusts of 80 mph expected around coasts in northern Scotland.

Figure 3. MODIS satellite image of Hurricane Ana brushing the Hawaiian Islands on Sunday morning October 19, 2014. At the time, Ana had top winds of 80 mph. Image credit: NASA.

Tropical Storm Ana bringing heavy rains to Hawaii
Tropical Storm Ana continues to trek westwards away from the Hawaiian Islands, but its outer bands are still bringing heavy rains to Oahu and Kauai, where Flash Flood Watches are in effect. Rainfall amounts of 3 - 6" with locally higher amounts are expected before Ana finally chugs out to sea. Ana dumped 3.4" of rain on Honolulu on Sunday, a record for the date. Satellite loops on Monday morning showed that Ana was holding its own against high wind shear, and the storm is likely to re-intensify into a hurricane by Tuesday when the shear relaxes.

Jeff Masters


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