EASING TOWARDS THE WINTER WITH A MILD NOVEMBER

Temperatures continue their quick descent into November as we reach the late stages of fall. Average highs across much of the north will drop into to the 40s and 50s while average highs in the south largely fall to the 50s and 60s. Some 70s and even lower 80s will linger across portions of the Southwest as well as near the Gulf Coast. Average lows dip into the 20s and 30s across the north and the 40s and 50s in the south. Daylight hours will be in the 9-11 hour range across most of the US.

A strong ridge was stationed over Central Canada to begin October, bringing summer-like heat to the Upper Midwest during the first 5-6 days of the month that broke a few records. Minneapolis saw the high temperature peak at 91 degrees on October 4. The only other time a 90-degree day occurred in Minneapolis on this date or later was in 1928. Above normal temperatures expanded through the South Central US and the Northeast during the first week of October, but were not as anomalous. The warm pattern continued through most of October across the Central US, though not to the magnitude of the first few days of the month. The one exception was with a cold front that brought modest cool anomalies to the Midwest over October 21-25 before warmer temperatures returned. This led to monthly temperature anomalies to be 3-7 degrees above normal across the Central US. With ridging focusing across the Central US, this allowed a trough to be a common feature across the West. This led to temperatures oscillating between near normal and below normal during October. Readings in the East generally ranged from near normal to a bit above normal for much of the month, but a trough ushered in a wave of cool anomalies to the East during the final week of October. Wetter than normal conditions were prevalent in October across the West. This was particularly the case across in Arizona and Utah, as moisture from the remnants of Hurricane Priscilla brought excess rainfall in during the second week of October. Most of the Central/Eastern US saw below normal rainfall in October, though a system late in October did produce regionally wet conditions from Oklahoma towards the Tennessee Valley. Four tropical systems formed in the Atlantic Basin this October. The first three – Jerry, Karen, and Lorenzo – all formed between October 7-13 but remained out to sea as tropical storms. Hurricane Melissa became the strongest hurricane of the season and had devastating impacts as it made landfall in Jamaica on October 28 with sustained winds at 185 mph. Melissa would continue to impact eastern Cuba and the southeastern Bahamas over the final couple days of October.

Troughing along the East Coast will be in place during the first week of November, leading to the month beginning with near to below normal temperatures in place with the coolest readings occurring over the first 3-4 days of the month across the Southeast. A large +EPO trough will become established near the Gulf of Alaska during the first week of November and will persist into the second week of the month. This will allow for a ridge to strengthen across the Interior West into the Central US, bringing widespread warm anomalies to the region. The warmest anomalies should favor the Rockies during the latter half of week one before shifting into the Plains during week two. The East Coast trough will be stubborn, making it difficult for the warmer airmass to extend into the East through mid-November. However, the Gulf of Alaska trough will ensure that milder Pacific-based air will be ushered across the US, limiting the risk of any substantial cold occurring in the East at the same time. This should result in oscillating temperatures during week two in the East. Warm anomalies should remain prominent across the Central US moving into the third week. Some of this warmer airmass should eventually seep into the Southeast, but a trough should remain stuck across eastern Canada, limiting the amount of warming across the Northeast. Slightly above normal temperatures should occur along the West Coast. Ridging could eventually shift into the Eastern US during the final 7-10 days of November, which should provide the most persistent period of above normal temperatures to the East during the month. As this occurs, a trough should settle across the West, increasing the chances for some cooler air to impact the region. Strong cold anomalies are not anticipated, however, as a trough near the Gulf of Alaska should remain in place and keep a Pacific-based airmass flowing into the US.

The Pacific Northwest should get off to an active start to November, with several systems bringing rain and mountain snow likely to impact the region over the 2-3 weeks of the month. This should ease to some degree during the final third of November, as the storm track could shift northward into western Canada instead. The other active storm track to begin November should be across the Great Lakes into the Northeast, especially late in week one and into the second week of the month. This should primarily fall as rain aside from higher terrain sections of the Northeast, but there is some risk for some snow to mix in with one or two of the later systems during the second week of November. The pattern should turn less active in the Northeast by the third week of November, with this trend continuing into the final third of the month. Drier than normal conditions are favored across the South through the first half of November. Rain chances may increase during the third week of November across the South Central US into the Midwest, including a risk for thunderstorms in the South Central US. While some wintry precipitation is possible in the Upper Midwest, snow chances overall should be below normal due to the warmer pattern. The South Central US should trend drier again late in November as the best opportunities for precipitation should return to the Northwest through the Northern Plains.

At this point in the season, the area to monitor for any tropical development will be over the eastern Caribbean Sea. This is where sea surface temperatures will be most conducive for tropical development, and it will be paired with below normal wind shear. However, tropical forcing will initially be unfavorable for development to occur in November, which will keep tropical formation risks below normal. Tropical forcing should become more favorable moving into mid-November. As this occurs, the period between November 15-25 will become the time frame that carries the best chances for a system to form in November. By this point in the season, above normal risks for tropical development does not mean that it is likely a storm will form, but it is worth monitoring.