Weekend split, cooler next week, El Nino brewing?

Wanted: Rain.

It's getting a little dry around these parts. Most of southern Minnesota is teetering on the edge of a drought hangover from  last fall. Soils were partially parched going into the freeze, and most of that snow melted away and ran off into rivers and lakes or evaporated into thin air the past two weeks.

Not much of our winter snows seep into the soils for recharge.

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Our thirsty soils get a short drink Saturday morning as low pressure passes overhead with a few showers and a clap of thunder possible.

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Sunday's system passes teasingly close to southern Minnesota. If we're lucky, a few of us may see some rain that could mix with wet snow at times. But it looks like most of the moisture will pass south of Minnesota and land on Iowa, southern Wisconsin and Illinois.

There is a slight risk for a few severe storms from near Omaha, Neb., through Des Moines, Iowa, to Chicago and Milwaukee, Wis., as the system slides in Saturday.

Yes, folks, it's time again to trot out the "risk areas" from the National Oceanic and Atmospheric Administration's Storm Prediction Center.

The severe treat slides south for Sunday.

Showers then much colder next week

Saturday's showers look to be on the lighter side. Most areas will pick up between .1 and .3 inch of liquid with a few lucky spots getting around a half inch in southeast Minnesota and Wisconsin.

Sunday's cold front will get your attention. Highs will stagger into the 40s early next week with some moderation likely later in the week.

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Weatherspark

El Nino Factor: Growing chances for a milder winter next year?

I would be tough to duplicate last winter's cold two years in a row. The latest trends in the tropical Pacific toward a possible developing El Nino may make it even tougher.

A growing number of ocean models now favor warming of  tropical Pacific sea surface temperatures (SST's) above the +0.5C threshold to trigger an El Nino event by next fall and winter.

Feed your inner weather geek with more details from NOAA's  El Nino Southern Oscillation Diagnostics Discussion.

EL NIÑO/SOUTHERN OSCILLATION (ENSO)

DIAGNOSTIC DISCUSSION

issued by

CLIMATE PREDICTION CENTER/NCEP/NWS

and the International Research Institute for Climate and Society

10 April 2014

ENSO Alert System Status: El Niño Watch

Synopsis: While ENSO-neutral is favored for Northern Hemisphere spring, the chances of El Niño increase during the remainder of the year, exceeding 50% by summer.

ENSO-neutral continued during March 2014, but with above-average sea surface temperatures (SST) developing over much of the eastern tropical Pacific as well as near the International Date Line  (Fig. 1). The weekly SSTs were below average in the Niño1+2 region, near average but rising in Niño3 and Niño3.4 regions, and above average in the Niño4 region (Fig. 2).

A significant downwelling oceanic  Kelvin wave that was initiated in January greatly increased the oceanic heat content to the largest March value in the historical record back to 1979 (Fig. 3) and produced large positive subsurface temperature anomalies across the central and eastern Pacific (Fig. 4).

Also during March, low-level westerly wind anomalies were observed over the central equatorial Pacific. Convection was suppressed over western Indonesia, and enhanced over the central equatorial Pacific (Fig. 5). Although these atmospheric and oceanic conditions collectively reflect ENSO-neutral, they also reflect a clear evolution toward an El Niño state.

The model predictions of ENSO for this summer and beyond are indicating an increased  likelihood of El Niño this year compared with last month. Most of the models indicate that ENSO-neutral  (Niño-3.4 index between -0.5°C and 0.5°C) will persist through much of the remainder of the Northern Hemisphere spring 2014 (Fig. 6), with many models predicting the development of El Niño sometime during the summer or fall.

Despite this greater model consensus, there remains considerable uncertainty as to when El Niño will develop and how strong it may become.

This uncertainty is amplified by the inherently lower forecast skill of the models for forecasts made in the spring. While ENSO-neutral is favored for Northern Hemisphere spring, the chances of El Niño increase during the remainder of the year, and exceed 50% by the summer (click CPC/IRI consensus forecast for the chance of each outcome).