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08/01/2018, 10:07 am EDT

Daily Tropical Feature: 2018 Outlook

Executive Summary: The Climate Impact Company 2018 North Atlantic basin tropical cyclone season forecast is updated on August 1st as the most active part of the 2018 season is underway. The seasonal outlook is very similar to the forecast issued May 31 and includes 11 tropical cyclones, 5 hurricanes and 1 intense hurricane. This outlook includes the 3 tropical cyclones and 1 hurricane which has already occurred in 2018. The accumulated cyclone energy forecast for the 2018 season has not changed at 58 which is much lower than last year’s 226 (3rd highest on record). The seasonal activity forecast is below normal but 2 hurricanes are forecast to strike the U.S. Coast most likely in the Southeast U.S. from the eastern Gulf of Mexico. Another hurricane is forecast to emerge in the warm waters off the U.S. East Coast. The outer tropical North Atlantic is dormant due to unusually cool surface water. El Nino is approaching which inhibits seasonal activity. The evolution of El Nino has slowed in recent weeks therefore it is possible that while the number of hurricanes forecast for 2018 is confident there may be more tropical storms if El Nino fails or is delayed until late in the year.  In the East Pacific the seasonal forecast indicates 17 tropical cyclones, 9 hurricanes and 5 intense hurricanes. Regional forecast summary: The outlook is based on analog year projections adjusted for regional factors and previously issued climate forecasts by CIC. Gulf of Mexico: The eastern Gulf of Mexico is forecast to encounter 2 northward moving hurricanes, one in August and another in October moving into the Florida Panhandle. One of these hurricanes is likely an intense hurricane. Other tropical cyclone activity is likely due to the warmer than normal SSTA in the Gulf region. Mexico: Due to westerly shear produced by an approaching El Nino episode Mexico is not expected to encounter a hurricane from the east. East Coast Virginia and north: The ocean surface is warmer than normal off the Northeast Corridor Coast and at least 1 hurricane in these waters is likely and occurs in September. Due to the warm waters other tropical cyclones are possible. East Coast south of Virginia: Significant tropical cyclone activity is likely into the eastern Gulf of Mexico off the west coast of Florida. Hurricanes turning into the east coast of Florida or Southeast U.S. is less likely. Caribbean: The Caribbean Sea is forecast much less active than last year given an approaching El Nino increasing upper westerly shear.
07/15/2018, 1:56 pm EDT

Subsurface Equatorial Oceans Offer Clues to the Climate Ahead

Subsurface Equatorial Oceans Foreshadow Climate Ahead Fig. 1:  ECMWF subsurface global oceans temperature anomaly analysis for June 2018. Discussion: Anticipated is evolution of an El Nino episode over the next 1-2 months in the eastern equatorial Pacific. However, the vast anomalous warmth across most of the equatorial Pacific Ocean (Fig. 1) in which the warmest anomalies are located in the East Pacific (usually foreshadowing El Nino ahead) are not reaching the surface leaving ENSO in neutral phase. The anomalous warmth across the entire equatorial subsurface is rare and may mean something other than a standard warm ENSO episode ahead. One possibility is El Nino Modoki which occurs when the anomalous warmth of an East Pacific El Nino is biased toward the Dateline rather than the northwest coast of South America as a standard El Nino produces. One of the strongest El Nino Modoki episodes on record, evolving during mid-to-late 2002 and peaking during that (northern hemisphere) winter also produced widespread anomalous warmth across the equatorial Pacific prior to onset of El Nino (Fig. 2). Fig. 2:  ECMWF subsurface global oceans temperature anomaly analysis for June 2018. Normally, the subsurface equatorial East Pacific is very warm while the subsurface West Pacific is near normal or cooler than normal when an El Nino develops. The importance of this potential different El Nino developing is extremely important. Recent El Nino Modoki episodes have correlated with cold winter seasons in both the eastern U.S. and Europe (versus a more typical mild climate that a standard El Nino produces). Meanwhile the upper ocean heat in the central/east-central Atlantic equatorial region is cooler than normal (and trending cooler). The cool upper ocean heat signature implies limited energy for hurricane development in the main development region for North Atlantic hurricanes in-between the Caribbean Sea and northwest coast of Africa. However, the warmer than normal Gulf of Mexico and waters off the U.S. East Coast are the most likely regions to produce and sustain tropical cyclones for the core of the season which is ahead (Aug. 1 to Sep. 30). Summary: Subsurface equatorial ocean temperatures (and their trend) can foreshadow surface temperature anomalies which correlate to prevailing climate conditions. In the equatorial Pacific the vast subsurface warmth is not dissimilar to June 2002 when El Nino that eventually formed produced a warm bias toward the Dateline in the East Pacific tropics correlating a cold winter in the eastern U.S. (after a mild winter was anticipated). El Nino Modoki is possible for 2018-19. In the North Atlantic tropics upper ocean heat to produce and sustain hurricanes is in low supply.
07/08/2018, 6:33 am EDT

Daily Tropical Feature: Category 4 Maria Heading for China

Fig. 1:  Category 4 Super Typhoon Maria is forecast to reach the China coast in 48-54 hours. Discussion: Category 4 Super Typhoon Maria in the east-central Pacific Ocean is forecast to move west-northwest, possibly attaining category 5 intensity and reach the central China coast as a super typhoon just north of Fuzhou in 48-54 hours. An elongated frontal system already northwest and north of the projected landfall location is producing heavy rains which will become more enhanced with the approach of Maria. Parts of the wheat, corn, soybean and rice crop areas in central/east China are affected by the heavy rains as midweek approaches. By next weekend a hot and dry pattern follows for most of the crop areas listed while another typhoon develops northeast of the Philippines which could reach the China Coast in the 11-15 day period.