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Typhoon Nuri Poised to Become an Alaskan Super Storm; TD Vance Hits Mexico

By: Dr. Jeff Masters, 4:22 PM GMT on November 05, 2014

Typhoon Nuri is down to Category 1 strength as it steams to the northeast at 11 mph towards Alaska. Satellite loops show that Nuri has maintained a large area of heavy thunderstorms, but the eye is no longer visible, and high wind shear of 20 - 30 knots is significantly disrupting the storm. Nuri will lose its tropical characteristics on Thursday as it becomes embedded in a cold front. As the extratropical version of Nuri moves into the Bering Sea to the west of Alaska on Friday, a very powerful jet stream will interact with the storm and cause it to rapidly intensify into one of the strongest low pressure systems ever observed in the Pacific Ocean. Ex-Nuri's central pressure is forecast to drop from around 970 mb late Thursday night to about 918 mb late Friday night. The 00Z Wednesday run of the European model predicted that ex-Nuri would bottom out near 918 mb at 03Z Saturday, about 300 miles west-northwest of the westernmost Aleutian Island, Attu. The 00Z Wednesday GFS model had the storm reaching 918 mb 300 miles north of Attu. The NWS in Anchorage is predicting that a large swath of hurricane force winds will be possible from Shemya eastward to Adak and Atka in the Aleutian Islands late Friday into Saturday, with seas building to 45 feet or higher. A storm surge of 2' is predicted at St. Lawrence Island on Saturday morning, and over 1' at Nome.

Figure 1. MODIS satellite image of Typhoon Nuri in the Pacific at 04:10 UTC November 5, 2014. At the time, Nuri was a weakening Category 2 storm with top sustained winds of 105 mph. Image credit: NASA.

Figure 2. Predicted sea level pressure for 03 UTC Saturday (10 pm EST Friday, November 7, 2014) from the 00Z Wednesday run of the European model. Ex-Nuri is predicted to be at peak intensity at that time, with a 920 mb closed isobar falling between the Russian station Nikol'Skoe and Attu Island in Alaska's Aleutian Islands.

Ex-Nuri predicted to become one of Earth's strongest storms on record
According to wunderground's weather historian Christopher C. Burt, the all-time Alaska low pressure record is 27.35" (926 mb) at Dutch Harbor on October 25, 1977. Ex-Nuri would have a chance to beat that record if its center passed over one of the Aleutian Islands on Saturday morning, but it appears that when the storm is at peak intensity, the center will miss any Aleutian Islands by a wide margin. Ex-Nuri is also likely to fall short of the lowest estimated pressure for any extratropical storm world-wide, the 26.96" (913 mb) pressure estimated for a January 11, 1993 storm off the Shetland Islands in the North Atlantic (documented in Christopher C. Burt's book, Extreme Weather.) Mr. Burt has a comprehensive post on all these records in his November 10, 2011 post, Super Extra-tropical Storms; Alaska and Extra-tropical Record Low Barometric.

Figure 3. Surface analysis for late evening October 25, 1977 when Alaska’s strongest storm in history deepened to 926 mb (27.35”) over Dutch Harbor on the Aleutian Island of Unalaska. Chart drawn by and supplied by wunderblogger Steve Gregory, who worked with the Ocean Routes Company (now WNI) in Alaska at the time.

Vance makes landfall in Mexico as a tropical depression
What was Category 2 Hurricane Vance on Tuesday morning made landfall on Mexico's Pacific coast southeast of Mazatlan Wednesday morning as a mere tropical depression with 30 mph winds. High wind shear of up to 50 knots rapidly tore apart the storm as it approached the coast. Vance is pushing inland to the northeast at 13 mph, and will dissipate Wednesday afternoon. Moisture from Vance is streaming to the northeast over Texas, and Flash Flood Watches are posted from Del Rio to Austin for 1 - 2 inches of rain, with isolated amounts up to 4 inches.

Figure 4. MODIS satellite image of weakening Tropical Storm Vance off the Pacific coast of Mexico on Tuesday afternoon November 4, 2014. Image credit: NASA.

Steve Gregory plans on doing a guest post in my blog Thursday afternoon: the forecast for the coming winter.

Jeff Masters


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