Weather Patterns Collide

It’s snowing again in Texas! Snow showers have been falling all day in the Lone Star State. Dallas, Texas has very few accumulations (snow on the ground), but hill country areas such as Waco have 3 inches of snow on the ground.

The National Weather Service has issued Winter Storm Warnings for Texas, California, New York and other parts of the Northeast.

Two weather patterns are colliding over the United States this winter to produce storm after storm for the southern Gulf Coast and the Northeast. The El Nino Southern Oscillation is a weather pattern that causes a warming of the Pacific Ocean off the coast of Central America. This winter, El Nino is being credited with the surge of moisture and added rainfall/snow events in California, Arizona, New Mexico, Texas, and the Gulf Coast.  At the same time El Nino is occurring, scientists are also examining the effects of a Negative Arctic Oscillation. The NAO is associated with cold winters across the Northern Hemisphere, as more cold air descends from the Arctic to the nearby continents of North America, Europe and Asia.

The above graphic is data taken from the entire month of December 2009. What this graphic shows is average temperatures across Asia, Europe and North America have been substantially cooler than normal, whereas temperatures in the Arctic, Africa and parts of the Mid-East have been warmer.

Take a look at the large dip of cold air across Minnesota, Iowa and the Dakotas. Once again, folks in Minneapolis will be waking up to below freezing temperatures. Look at the forecast lows across Louisiana… below freezing. If you add the extra moisture coming in from the Pacific due to El Nino and the cold air due to the Arctic Oscillation, you have the perfect recipe for snow.

TV forecasters in Shreveport and New Orleans, Louisiana are reporting once again on the unusual snowfall events.  In the Northeast, where snow has caused massive transportation problems, another round this week is expected.

-Dawn Brown

Is Cooler Air Here to Stay?

Look at the snow! This is a picture of the average snow depth across the United States on this Sunday. What’s interesting about this picture is not the fact that five percent of the country is covered in snow. The percentage is not that unusual for the month of October. What is unusual is where the snow is located.  When I look back at the snow analysis for the middle of October for that last ten years, most of the early season snow occurred over the Rocky Mountains. This year, the Great Lakes, Appalachians, Upstate New York and New England have snow accumulations. (Source : National Snow Analysis )

This goes hand-in-hand with the cooler than average summer experienced by the Great Lakes and Eastern Seaboard as well. The upper air pattern continues to bring cooler weather to these regions. However, as I posted on Wednesday, this cool summer is no indication of what winter will look like in the same areas. In fact, NOAA is forecasting a warmer than average winter across the northern tier states. On Thursday, NOAA published its El Nino Outlook, with newer and (much prettier) pictures than I created on my blog last Wednesday, showing folks the climate outlook for this winter.

You can see from the first image above that the Pacific Northwest and Ohio and Tennessee River Valleys are expected to be drier than average. And the entire northern half of the United States is expected to be warmer. Sweet relief will come to the Southeastern States, with a cooler than average winter. Higher than average precipitation is expected for California and the Southern United States. (This the forecast for December through February.)

Today, cold weather warnings have been posted all across the Ohio and Tennessee River Valleys for states from Ohio and Pennsylvania to Alabama and Mississippi. Here’s the latest TV forecasts from FOX Nashville and Biloxi, Mississippi.

Great football weather! Enjoy the games.

-Dawn Brown

Cool Air Dips South, El Nino Rains in Cali?

Cool air is finally surging toward the South. On this visible satellite image, captured at about 3pm EST today, you can see the dense overcast clouds across the Central Plains. Temperatures are dropping to the 30s, 40s, and 50s in many locations. In Lake Charles, Louisiana, the forecast high is expected to drop from the upper 80s to the mid 70s by Friday.

In California, rain will finally taper off this evening into Thursday. At the bottom of this article, you’ll find the one day record rainfalls posted by the National Weather Service offices for Los Angeles and San Francisco.

Los Angeles TV forecasters have the latest on the storms in Southern California, while the Bay Area forecast can be seen on San Francisco TV.

Above average rainfall across the southern United States is usually forecast during an El Nino year.

According to the NOAA scientists, “El Niño’s impacts depend on a variety of factors, such as intensity and extent of ocean warming, and the time of year. Contrary to popular belief, not all effects are negative. On the positive side, El Niño can help to suppress Atlantic hurricane activity. In the United States, it typically brings beneficial winter precipitation to the arid Southwest, less wintry weather across the North, and a reduced risk of Florida wildfires.

El Niño’s negative impacts have included damaging winter storms in California and increased storminess across the southern United States. Some past El Niños also have produced severe flooding and mudslides in Central and South America, and drought in Indonesia.” ( Source: NOAA )

According to NOAA, the 2009-2010 El Nino is expected to strengthen during this upcoming winter period.

…RECORD 24 HOUR RAINFALL SET OR TIED AROUND THE SAN FRANCISCO AND MONTEREY BAY AREA TUESDAY OCT 13…

STATION NEW RECORD OLD RECORD

KENTFIELD 6.14 4.20 SET IN 1957

OAKLAND MUSEUM 3.86 0.37 SET IN 1988

RICHMOND 3.38 2.47 SET IN 1962

SAN FRANCISCO AIRPORT 2.64 2.62 SET IN 1962

SAN FRANCISCO DOWNTOWN 2.49 1.80 SET IN 1962

SANTA ROSA 2.74 (TIED) 2.74 SET IN 1962

KING CITY 1.65 0.30 SET IN 2007

MONTEREY CLIMATE STATION 2.66 1.14 SET IN 1962

SALINAS 1.05 0.39 SET IN 1992

SANTA CRUZ 3.16 2.49 SET IN 1957

…RECORD RAINFALL REPORTS FOR TUESDAY OCT 13…

STATION NAME NEW RECORD OLD RECORD

PASO ROBLES 1.80 INCHES 1.41 INCHES IN 1968

SANTA BARBARA APT 1.67 INCHES 0.62 INCHES IN 1957

WFO OXNARD 0.51 INCHES 0.34 INCHES IN 1962

BURBANK APT 0.59 INCHES 0.33 INCHES IN 1957

WOODLAND HILLS 0.66 INCHES 0.27 INCHES IN 2007 (PIERCE COLLEGE)

SANDBERG 0.57 INCHES 0.09 INCHES IN 1957

Cold Blast North, Cooler South

The national radar map is pretty quiet this Sunday morning after a stormy week that left much of the Central Plains and Mid-Mississippi River Valley with flooding rains and standing water. Cold air is the rule across the Northern Plains, winter weather advisories are in effect for the South Dakota, Wyoming, Nebraska and Minnesota. Snow will be on the ground in some states. Meanwhile frost advisories are in effect for the Northeast as they prepare for a cold blast. It is the middle of October and the cool summer is turning into an early winter for much of the northern half of the country.

However, keep in mind folks that El Nino is still in effect. An El Nino pattern usually means a mild winter for the northern tier states. So, even though you’re getting hit by some winterlike storms now, it’s not an indicator for bitter cold this winter season.

Meanwhile, the deep South is getting some relief from the burning temperatures last week. A cold front slipped all the way into the gulf of Mexico, dampening the rain chances this weekend and allowing for cooler, drier air to slide in. The Southern states will see that cool air erode again next week.

-Dawn Brown