Thursday, December 27, 2012

A wet end to a busy Louisiana weather year | NOLA.com

The end of a busy weather year promises two more chances of rainfall, including on New Year's Eve. It will mark a wet end to 2012, which began with near-drought conditions in New Orleans.

Forecasters with the Slidell office of the National Weather Service are expecting another cold front to usher in showers and thunderstorms to the area Friday and Friday night."A few strong to severe thunderstorms are possible during the afternoon and early evening hours," says the service's hazardous weather outlook message. "The main threat will be damaging winds."

Expect highs in the upper 60s on Friday, accompanied by winds of 15 to 20 mph out of the southeast, with an 80-percent chance of precipitation. Temperatures will drop into the upper 40s Friday night, with winds shifting to out of the northwest at 15 to 25 mph after midnight.

Saturday will be cooler under partly cloudy skies, with highs in the 50s, and winds out of the north at 15 to 25 mph. The temperature will drop into the upper 30s in New Orleans and lower 30s on the north shore overnight Saturday, and reach only the lower 50s during the day on Sunday.

By Monday, the chance of rain begins to increase again, as high temperatures rise into the lower 60s. There's a 40 percent chance of showers for New Year's Eve, continuing into New Year's Day and Tuesday night, with highs in the mid-60s and lows in the 40s.

Things get cooler again on Wednesday, with highs only in the 50s, still under mostly cloudy skies with a continuing chance of rain.

While rain has been a significant story during 2012, it's the storm surge delivered by Hurricane Isaac on Aug. 29, exactly seven years after Katrina, that was the top weather story of the year, according to Louisiana State Climatologist Barry Keim.

?"The two areas hardest hit were Braithwaite and LaPlace, where several neighborhoods were inundated," he said. "It occurred amidst a busy 2012 hurricane season that was headlined by Hurricane Sandy."?Although only a Category 1 on the Saffir-Simpson wind scale, Isaac again proved that scale's limitations, as its slow forward speed and direction resulted in surge levels of more than 13 feet at the Lake Borgne barrier on the edge of eastern New Orleans and water heights of 7 feet in Lake Pontchartrain, Keim said.

Sandy had lost its tropical characteristics, but not its storm surge, as it hammered a significant portion of the East Coast, including the New York and New Jersey shorelines, in late October.?

?The second biggest weather story of the year was one that few people in the New Orleans area probably noticed: the unusually low level of the Mississippi River during much of the year.

"Obviously, that had nothing to do with drought conditions in Louisiana, but rather drought that was experienced across the Great Plains and the Midwest," Keim said, resulting in low rates of rainwater runoff entering the river.

Ironically, river water levels were so high in 2011 that the Army Corps of Engineers was forced to open both the Bonnet Carre Spillway west of New Orleans and the Morganza Floodway adjacent to the Old River Control Structure north of Baton Rouge.

But by mid-year 2012, water levels in the river were so low that Plaquemines Parish had to stop drawing drinking water from the river and switch to an alternative water supply, because saltwater from the Gulf of Mexico had traveled upstream to the parish's river water intake structures.

In August, the corps awarded a $5.8 million contract to a dredging company to build an underwater dam in the river channel at mile marker 65, to block the salt water before it reached the drinking water intakes for the city of New Orleans and Jefferson Parish.

Corps officials continue to check the dam at least once every two weeks to assure it hasn't eroded away, although higher water levels in the river during the past two weeks have helped keep the leading edge of salt water farther downstream.

On Thursday, the Mississippi was still at only 3.2 feet at the Carrollton Gauge in New Orleans, and is forecast to rise only to about 5 feet before dropping to 3 feet again by Jan. 18, according to the Lower Mississippi River Forecast Center.

The third biggest weather story has been the state's flirtation with drought conditions during the year, Keim said.

"Statewide, rainfall amounts are going to be above normal for the year, but the timing and geographic location of the rain was irregular," he said. "We're still seeing regional drought conditions, with water levels above normal in the south, but not in the north, and vice versa for drought. But the majority of weeks this year had some part of Louisiana listed in drought conditions."

As of Thursday, New Orleans International Airport had measured 67.7 inches of rain, or almost 6 inches above normal, while Shreveport had measured 49.9 inches, almost an inch below normal.

Still, total rainfall amounts statewide were significantly higher this year than last, when more severe drought conditions were experienced throughout the state.

Last year, Shreveport had only 33 inches of rain, or close to 18 inches below normal, while the New Orleans airport saw 54.6 inches, or 7 inches below normal.

Indeed, the recent outbreaks of cold weather may stave off a record for the average statewide temperature for the year, Keim said. According to the National Climate Data Center, the average temperature for 12 months through November was 69.9 degrees, which was 1.9 degrees warmer than the 20th Century average annual temperature, and ranked as the 5th warmest similar 12-month period. The record for the same period was in 1927, when the average temperature was 70.6 degrees.

Source: http://www.nola.com/weather/index.ssf/2012/12/a_wet_end_to_a_busy_louisiana.html

lsu alabama lsu game lsu game beezow doo doo zopittybop bop bop cordova demaryius thomas transtar

No comments:

Post a Comment

Note: Only a member of this blog may post a comment.