By Meteorologist Tom Skilling
It's the wet, stormy pattern many West Coast residents love to hate--the so-called Pineapple Express. The pattern involves a huge swath of moist winds which originate in the equatorial Pacific west of Hawaii--thus the name. Satellite imagery late Friday indicated its "plume" (corridor) of moisture was gargantuan, extending at least 4,900 miles from the central equatorial Pacific into the Rockies, where radars were "lighting up" as precipitation erupted.
The Pineapple Express' arrival not only signals the start of that region's annual rainy season, but also threatens to unleash huge low-elevation downpours, which by Christmas Eve (next Friday) could amount to 8 to 12 inches adjacent to southern California's mountains outside Los Angeles and San Diego--enough rain to provoke flooding and mudslides, particularly along westward facing slopes. While rains could end up troublesome at low elevations, the succession of storms predicted to hit the region with huge precipitation tallies could be a bonanza for western skiers which, in California's Sierra range alone, may be looking at staggering 10-foot snow accumulations in the days ahead.
Weather troubles with the Pineapple Express won't be limited to California alone. Far from it! Warnings of rough weather this weekend and beyond are out across sections of 10 western states. And the impact of this stormy atmospheric regime may ultimately extend to the Midwest and areas east.
Computer model estimates of the snow which may fall in Chicago the next two weeks have surged. Temperatures with each Pacific storm system predicted to impact this area, will have to be closely monitored since they may affect how much of the precipitation in coming weeks falls as snow versus rain or a mix. As an example, there are early indications, a period of accumulating snow may fall here by Monday afternoon and into Monday night--only to mix with drizzle or freezing drizzle for a time by Tuesday morning before returning to snow showers. Similarly, while snow with a second late week system could arrive toward Friday (Christmas Eve), milder temperatures nearby raise questions about how much snow may fall.
Two of Friday's four runs of the National Weather Service's 16 day Global Forecast System (GFS) model estimate the metro area could be in for a cumulative foot of snow by month's end--an amount two to three times the period's long-term-average of 3.9 inches. But, even a partial shift to rain or a mix could lower those numbers.
Chicago December snow 180% normal; heading for fourth consecutive December to post big snow numbers here
Chicago's generous December snow tally of 7.6 inches is already well above average. It's 180 percent of the long-term (126 year) average of 4.2 inches to date.
It's worth noting Christmas Eve and Christmas Day snows have occurred in 53 and 56 percent of the past 126 years respectively. Yet, only 13 percent of those years have produced an inch or more of snow--and the area's last 2 inch snow on either day occurred 8 years ago in 2002. It's been 59 years since the period has included an 8 inch or greater snow. That last happened December 24-25, 1951 when 8.6 inches fell.
Syracuse, New York closing in on all-time snow record with nearly half the U.S. covered by snow--a season high
Chicago isn't alone with a generous December snow tally. In Syracuse, New York, December snows have come on especially strong. The city's received 70.8 inches of snow at its International Airport--breaking the old December full-month average of 70.3 inches set in 2000 and putting the month on a path to possibly becoming the snowiest month there ever. The snowiest month currently on the books in Syracuse is 78.1 inches set in January 2004.
A U.S. snow cover analysis produced Friday by NOAA--the National Weather Service's parent agency--indicates 47 percent of the country sits beneath a layer of snow. That's the highest fraction of the U.S. to be snow covered to date this season.
Computer model 2 week Chicago snow estimates 2-3 times normal
Computer estimates of this area's average snowfall between now and New Year's Day suggests an average of 11.2 inches of snow may fall. If true, that's just shy of three times (287 percent) the normal amount for the period.
It's the wet, stormy pattern many West Coast residents love to hate--the so-called Pineapple Express. The pattern involves a huge swath of moist winds which originate in the equatorial Pacific west of Hawaii--thus the name. Satellite imagery late Friday indicated its "plume" (corridor) of moisture was gargantuan, extending at least 4,900 miles from the central equatorial Pacific into the Rockies, where radars were "lighting up" as precipitation erupted.
The Pineapple Express' arrival not only signals the start of that region's annual rainy season, but also threatens to unleash huge low-elevation downpours, which by Christmas Eve (next Friday) could amount to 8 to 12 inches adjacent to southern California's mountains outside Los Angeles and San Diego--enough rain to provoke flooding and mudslides, particularly along westward facing slopes. While rains could end up troublesome at low elevations, the succession of storms predicted to hit the region with huge precipitation tallies could be a bonanza for western skiers which, in California's Sierra range alone, may be looking at staggering 10-foot snow accumulations in the days ahead.
Weather troubles with the Pineapple Express won't be limited to California alone. Far from it! Warnings of rough weather this weekend and beyond are out across sections of 10 western states. And the impact of this stormy atmospheric regime may ultimately extend to the Midwest and areas east.
Computer model estimates of the snow which may fall in Chicago the next two weeks have surged. Temperatures with each Pacific storm system predicted to impact this area, will have to be closely monitored since they may affect how much of the precipitation in coming weeks falls as snow versus rain or a mix. As an example, there are early indications, a period of accumulating snow may fall here by Monday afternoon and into Monday night--only to mix with drizzle or freezing drizzle for a time by Tuesday morning before returning to snow showers. Similarly, while snow with a second late week system could arrive toward Friday (Christmas Eve), milder temperatures nearby raise questions about how much snow may fall.
Two of Friday's four runs of the National Weather Service's 16 day Global Forecast System (GFS) model estimate the metro area could be in for a cumulative foot of snow by month's end--an amount two to three times the period's long-term-average of 3.9 inches. But, even a partial shift to rain or a mix could lower those numbers.
Chicago December snow 180% normal; heading for fourth consecutive December to post big snow numbers here
Chicago's generous December snow tally of 7.6 inches is already well above average. It's 180 percent of the long-term (126 year) average of 4.2 inches to date.
It's worth noting Christmas Eve and Christmas Day snows have occurred in 53 and 56 percent of the past 126 years respectively. Yet, only 13 percent of those years have produced an inch or more of snow--and the area's last 2 inch snow on either day occurred 8 years ago in 2002. It's been 59 years since the period has included an 8 inch or greater snow. That last happened December 24-25, 1951 when 8.6 inches fell.
Syracuse, New York closing in on all-time snow record with nearly half the U.S. covered by snow--a season high
Chicago isn't alone with a generous December snow tally. In Syracuse, New York, December snows have come on especially strong. The city's received 70.8 inches of snow at its International Airport--breaking the old December full-month average of 70.3 inches set in 2000 and putting the month on a path to possibly becoming the snowiest month there ever. The snowiest month currently on the books in Syracuse is 78.1 inches set in January 2004.
A U.S. snow cover analysis produced Friday by NOAA--the National Weather Service's parent agency--indicates 47 percent of the country sits beneath a layer of snow. That's the highest fraction of the U.S. to be snow covered to date this season.
Computer model 2 week Chicago snow estimates 2-3 times normal
Computer estimates of this area's average snowfall between now and New Year's Day suggests an average of 11.2 inches of snow may fall. If true, that's just shy of three times (287 percent) the normal amount for the period.
