Heavy Rains Hit Illinois

A large, slow-moving winter storm has dropped considerable rainfall across Illinois in the last few days. Here is the map of the amounts in the last 7 days, through this morning (12/28). Areas in shades of red are 5 to 8 inches, and follow Interstate 70 across Illinois. Areas in shades of yellow to light brown are 2 to 5 inches. I’ll post more when the rain finally ends.

AHPS Precipitation Analysis

And it’s still raining. There is the potential for another 0.75 to 1.25 inches expected in southern and central Illinois. Another 1.25 to 1.75 inches is expected in parts of northern and western Illinois before this system moves on.

Is this El Niño?

Continue reading

Warmer-than-average December in Illinois

The NWS released their latest forecast for December and it is calling for very strong odds of a warmer-than-average December for Illinois and a large portion of the United States. They put the chances at 70 percent or higher in northern Illinois and the Great Lakes region. The odds are between 60 and 70 percent for the rest of Illinois. Those are about the strongest odds that I have ever seen in a monthly forecast.

This forecast for December is strongly supported by the various forecasts out to 14 days, which are also calling for very strong chances of above-average temperatures.

 

off15_temp

The precipitation forecast is not as striking – increased odds of wetter-than-average conditions in the south and along the East Coast. That’s a classic El Niño precipitation pattern in winter months for those regions.

off15_prcp

Latest Seasonal Forecasts for Illinois – A Mild Winter?

The NWS Climate Prediction Center released their latest seasonal forecasts today. Here are the results for Illinois. The biggest news is that Illinois has an increased chance of above-average temperatures and below-average precipitation for the winter months of December, January, and February. This forecast is based largely on the developing El Niño in the Pacific Ocean.

While the forecast of a milder winter may sound appealing, I would not leave the winter coat in the closet and throw away the snow shovel just yet. Two things to consider are: 1) this is not a 100% guarantee, other factors come into play in determining our winter weather, and 2) even a mild winter can contain short periods of intense cold and abundant snowfall.

Slide33

More on the seasonal forecast

Continue reading

El Nino and the Latest NWS Outlook for Summer, Fall, and Winter

Summary: According to the NWS Climate Prediction Center, El Niño has arrived and has a 90% chance of staying this summer and an 80% chance of remaining through the end of 2015. In terms of strength, this El Niño is expected to be weak to moderate. Illinois is expected to have an increased chance of cooler-than-average conditions in the late summer and on into fall.

The El Niño event has finally arrived and heavily influenced the NWS climate outlooks released this morning. For June (first figure, top row), the Southern Plains are expected to have an increased chance of cooler-than-average temperatures. A large part of the US is expected to have an increased chance of wetter-than-average precipitation, including the southern two-thirds of Illinois.

For the period June-August (first figure, second row), the increased chance for cooler-than-average conditions stretches northward and eastward and includes far western Illinois. The  increased chance for wetter-than-average conditions does not cover Illinois. This should not be a concern since no part of Illinois is in drought now.

Later forecasts for July-September, August-October, and September-November show in increased chance of cooler-than-average across Illinois (see second figure for the July-September temperatures). Continue reading

A Weak El Nino Has Arrived, Another Winter Storm for Southern Illinois

1680v1_20150305-ElNino_arrives_1200
El Niño Arrives in 2015. This image shows the average sea surface temperature for February 2015 as measured by NOAA satellites. The large area of red (warmer than average) can be seen extending through the equatorial Pacific. (Credit: NOAA)

Today the National Weather Service reported that the long-awaited El Niño has arrived in the Pacific Ocean. El Niño occurs when we have above-average temperatures in the Pacific Ocean along the equator. It alters the Pacific weather pattern, which in turn alters our weather patterns over the US. The NWS forecasters say “it is likely (50 to 60 percent chance) that El Niño conditions will continue through summer. ” Due to the weak nature of this event, they are not expecting widespread or strong impacts from this event.

In other news, far southern Illinois was hit this week with another winter storm that passed through Arkansas; southeastern Missouri;  southern Illinois, Indiana, and Ohio; as well as most of Kentucky and points beyond. Some of the largest snowfall totals from this event include Grand Chain Dam with 10.0 inches and Brookport Dam with 9.0 inches.

snow-south

Latest Outlook for Winter in the US

Today the NOAA Climate Prediction Center released their latest winter forecast. First, there are two important notes about the winter forecast. One is that El Niño has not arrived yet, and if it does, it is expected to be mild.

The other point is that the current conditions are not always a reliable predictor of future conditions. In other words, just because we are having a cold November (9 degrees below average), that does not doom us to another cold winter. To give a recent example, November of 2012 was 1.3 degrees below average, while the following winter of 2012-13 was 3.0 degrees above average.

The first panel shows the temperature odds for December-February, our core winter months. Southern Illinois has a slightly elevated chance of colder-than-average temperatures as does most of the southern states. There is a stronger chance that temperatures will be above-average on the West Coast and Alaska.

DecJanFeb_temp_outlooks_with_pies_610

The second panel shows the precipitation odds for winter. The outstanding feature for us is the large area around the Great Lakes with an increased chance of being drier-than-average that covers all of Illinois.

DecJanFeb_precip_outlooks_with_pies_610

El Nino and the Midwest

NOAA has released a new 2-page fact sheet on El Niño and the Midwest (links below). Several people in the Midwest had input into this, including myself. El Niño typically results in warmer and drier than average winters. Confidence in these patterns is higher during stronger El Niño events.

Right now the NOAA Climate Prediction Center states that El Niño is favored to begin in the next 1-2 months and last into spring of 2015. The current thinking is that the odds are 2-in-3 in favor of it arriving and that the event will likely remain weak throughout its duration.

PDF version: EN-MW-Sep2014

Online version: