For much of this year, we have been in-between an El Nino and La Nina sea-surface temperature event called “La Nada.” El Nino is the abnormal warming while La Nina is the abnormal cooling of ocean waters in the south-central Pacific Ocean.
Early this year, sea-surface temperatures were warming, which was pointing to a new El Nino event. Within the last 4-6 weeks, there has been significant cooling of sea-surface temperatures along the Equatorial regions of the Pacific Ocean. The graphic shows the area of cooler waters along the Equator, the region that often determines whether we have a La Nina or El Nino.
This new direction of additional cooling along the Equator prompted the National Oceanic and Atmospheric Administration to release a La Nina warning in September. They are saying the chances of that cooler phenomenon forming this late fall and winter season are about 55 to 60 percent. From the newest data, Cliff and I believe that a new La Nina will be declared within the next several months.
Also, we’re still in the middle of tropical storm and hurricane activity, so we wouldn’t be surprised to see another major hurricane threaten the U.S. coastline between now and early November. Both Irma and Harvey combined have resulted in damage totals around $300 billion. Puerto Rico was destroyed by Hurricane Maria and damage totals could be near $100 million. In recorded history, we’ve never seen three Category 4 hurricanes strike the U.S. Mainland or its territories.
Despite the much-needed moisture, “extreme” to “exceptional” drought conditions still persist across eastern Montana, according to the latest Drought Index. Across North Idaho, we have “moderate” drought conditions from Coeur d’Alene westward into eastern Washington thanks to one of the driest summer seasons in history. The mountains of eastern Idaho are currently experiencing “severe” drought.
Although seasonal moisture totals across the region are above normal levels, the Northwest’s dry summer led to one of the worst wildfires seasons ever. Recent moisture in these areas has helped the fire situations, but there are about 20 major fires burning across the West as of late last week.
While ocean waters along the Equatorial regions are cooling down, we’re also seeing a lot of ocean warming in the western portions of Gulf of Alaska. However, to the east, north of Hawaii, ocean waters are cooler than normal. This pattern could lead to a drier than normal winter in the Southwest with colder temperatures late this year in the central U.S. In the Arctic regions, ocean temperatures continue to be well above normal, more than 5 degrees. This may be one reason we’re hearing about the recent rapid melting of ice in the Arctic.
If the La Nina builds in the coming weeks and months, the northern U.S., including North Idaho, may be in for a snowier than normal season, especially north of I-80. The southern part of the country would likely turn drier than normal.
According to NOAA, forecasters say that the start of the winter season across the North Country may be warmer than normal through the end of the year. But, conditions would likely turn colder and snowier after the first part of the year.
In terms of our near-term weather, October has arrived and Cliff and I don’t see a repeat of the huge moisture totals of October 2016. Our normal precipitation for this month is 2.22 inches. Last year, we had an amazing 8.88 inches, making it the second-wettest month in Coeur d’Alene’s history since 1895. The month with the most precipitation occurred in December of 1933 with a total of 9.91 inches. November of 1973 is the third wettest with 8.76 inches and January of 1998 had 8.70 inches of precipitation.
For this month, we think that precipitation totals should be above the 2.22-inch normal, but not close to that near-record total of October 2016, as most of the moisture is expected after the middle of the month. November may likewise be above normal as it appears the pattern is setting up to direct Pacific storms from the Gulf of Alaska and into our region. The National Oceanic and Atmospheric Administration (NOAA) is also predicting above normal moisture for the northwestern U.S. over the next three months.
By the way, the normal precipitation for November is 3.07 inches with an average of 8.7 inches of snow. December normally has 3.90 inches of moisture with an average of 11.3 inches of snow. For January, the normal snowfall is 21.4 inches with 3.79 inches of rain and melted snow.
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Contact Randy Mann at firstname.lastname@example.org