10/03/2023, 8:39 am EDT

U.S. Week 2-4 Outlook: East is cooler for mid-to-late October.

Chart of the day: U.S. drought worsening during early autumn. Discussion: The U.S. drought worsened entering October including rainfall deficits reaching the 12-15 in. range in parts of Southeast Nebraska and Southeast Iowa. Drought restrengthened in Kansas, parts of the Southeast States, and the Carolinas. Only the southern half of Florida, southern New England, and the coastal Northwest turned wetter. Week-2 Ahead Forecast valid October 10-16, 2023: Cooler East. Discussion: The upper trough in the East is triggered by a sharp -NAO pattern early in the period. Unseasonably cool air into the East into the middle of next week moderating late week. Forecast trend is wetter in the northern Great Plains and Louisiana but that rain is unlikely to raise low water on the Mississippi River. Substantial rain is forecast for the Northwest States. Week-3 Ahead Forecast valid October 17-23, 2023 (previous below): Wetter East. Discussion: Upper trough keeps the Central/East-central U.S. temperate (and possibly cooler than shown) while on the East Coast, the trough causes a wet regime. Hot and dry in the Southwest U.S. to the north of late season tropical cyclones impacting Western Mexico. Week-4 Ahead Forecast valid October 24-30, 2023: Cooler look for October continues. Discussion: The cooler look to the October outlook is maintained for the last week of the month as much of the U.S. is near normal except very warm in the Southwest U.S. A showery pattern near the U.S./Canada border with a tropically wet regime indicated in the Caribbean Sea.
10/03/2023, 8:35 am EDT

North Atlantic Basin Tropics Week 2-5 Outlook

Headline: Watching Bay of Campeche next week and northwest Caribbean Sea remainder of month. Table of the day: Activity so far this year.   Tropical Cyclones (Normal) Hurricanes (Normal) Intense Hurricanes (Normal) ACE Index (Normal) October 2 18 (11.0) 6 (5.3) 3 (2.4) 126.8 (96.8) CIC 8/2/23 Forecast 17 6 2 114 CSU 8/7/23 Forecast 20 9 4 160 Discussion: Seasonal activity for 2023 (based on ACE index) is 130% of normal so far. A total of 6 hurricanes and 3 major hurricanes have been observed, each close to normal. However, 18 tropical storms are much above normal. Seasonal activity in 2023 will be the most active on record for an El Nino year. The unusually active season for an El Nino year is attributed to the record warm North Atlantic basin. The 2023 season is not over yet. Below are expectations for the remainder of October. Week-2 Valid October 10-16, 2023: ALERT for Bay of Campeche. Discussion: GFS is on-and-off with a significant tropical cyclone forming in the Bay of Campeche next week. Forecast confidence for a system developing in this region is increasing. If a system develops, westerly wind aloft takes the storm toward southern Florida. There is some risk (overnight GFS) that a storm could drift north toward the Gulf Coast. Additionally, a storm well-out-to-sea is possible. Week 3 Valid October 17-23, 2023: ALERT issued for Cuba and vicinity. Discussion: An ALERT is issued for Cuba and vicinity and for the outer tropics. Development near a land mass inhibits potential. Week 4 Valid October 24-30, 2023: 2 ALERT areas for late month. Discussion: The warm North Atlantic tropics sustain ALERTS for the northwest Caribbean Sea and east-central tropics. Week 5 Valid October 31-November 6, 2023: North and south of Cuba has potential for a late season system.    Discussion: Formation off West Africa is unlikely despite the tropical rainfall. However, an ALERT is issued for the northwestern Caribbean Sea to the Bahamas for early November potential.