Wednesday, February 17, 2016

It's Been A Wild, Wacky Winter

ONI values for six strong El Niño events
compared to the current El Niño (red).

The development of El Niño in the fall and winter was much anticipated, and for the most part it has lived up to expectations in development and strength. It has been generally warmer than normal across the eastern two thirds of the nation, and snowfall has been below normal except in the mid-Atlantic and southeast, where it has been above normal. While the Pacific Northwest has received plenty of rain and snow, southern California is still waiting for drought-denting rain that the El Niño pattern was supposed to favor. December was warm everywhere except in the west, and January was warm as well, with volatile weather the middle of the month. February has been a roller coaster ride so far in the eastern half of the country.

In the past three weeks we've seen blizzard warnings issued four times, in the northern Plains, the mid Atlantic coast, southern New England, and a second time in eastern New England. This past week we've seen snow and sleet in the southeast, snow and freezing rain in New England, and severe thunderstorms and tornadoes from the Gulf Coast through Florida. Last weekend a surge of Arctic air spilled into the northeastern U.S. producing record cold weather from Michigan south to Virginia and across the Northeast.
Record lows for Sunday morning, February 14, 2016.
Credit: AerisWeather 

As quickly as the cold came, it retreated back north, but no without creating a mess. Warm air surged in aloft but the cold air hugged close to the surface, eventually resulting in freezing rain across much of New England. That brought down trees and power lines leaving thousands without power on Monday. The warm reached far north into Maine with highs nearing records in the upper 40s. On the cold side of this system, heavy snow fell in Ontario, Canada, with a record 51.2 cm (20.2 inches) of snow on Tuesday, February 16.

Maximum temperatures for 12 hour period ending 7:00 p.m. EST February 16, 2015

The warm air and strong winds decimated the snow cover. The snow depth on Bangor, ME went from 11 inches on Tuesday morning to zero this morning. The warm air also resulted in ice breakup on some rivers and ice jams, in turn, brought the threat of flooding. Meanwhile, in the southern U.S. more than 14,000 people were without power after severe storms and tornadoes tore through the Gulf Coast states and the southeast on Tuesday.

The last two days have brought unseasonable heat to the southwestern United States from southern California through Arizona and New Mexico. Los Angeles set a record high of 90°F on Tuesday (downtown) and other records were set across southern California. Record high were set across New Mexico and Arizona Wednesday, with Phoenix reaching a record high of 90°F, the earliest 90°F has occurred. Tuscon reached a record 91°F, and was the nation's highest temperature on Wednesday. The exceptionally warm, dry weather, brisk winds, and low humidity have combined to produce extreme fire danger over a portion of the southwest  and Plains on Thursday.

Fire weather outlook for Thursday, February 18, 2016.

Unseasonably mild air will shift in to the central U.S, by the end of this week, bringing an early taste of spring with highs expected to reach the 60's as far north as Iowa and Illinois.

Maximum temperature forecast for Friday, February 19, 2016

There's a little less than half of February remaining, and we'll see where the roller coaster takes us in the next two weeks. It's unlikely that were done with winter just yet.

Thursday, February 4, 2016

A Wet Winter in the Sunshine State

Northern snowbirds heading to Florida this winter have not experienced the normal "dry season" that typically occurs during the winter. The development of El Niño this year has modified the overall storm track across the southern U.S., and the southeastern U.S., particularly southern Florida, has experienced a wet winter.

November was very wet across the Carolinas and Georgia. Precipitation across Florida was normal to lightly above in Florida except for the far south, where precipitation was 1.5 times normal. In December the Carolinas, Georgia, and Alabama were wet with precipitation two to three time normal. However, there was an amazing precipitation gradient across Florida. The western panhandle experienced much above normal rainfall, but across the remainder or northern and central Florida precipitation dropped to as low as 25 percent of normal. Rainfall then increased markedly from central Florida to to 500 percent of normal or more across the southern tip of the state.

Monthly totals across southern Florida reported by CoCoRaHS observers ranged from 10 to more than 19 inches of rain. The bulk of the December rain fell during the first week of the month from December 4-6. A stationary front extending from the western end of Cuba across the Florida Keys and strong onshore flow  produced by strong high pressure to the north provided the fuel and the mechanism to produce torrential rain especially over Miami-Dade County.

Daily rainfall in December 2015 for CoCoRaHS station Fl-MD-22 Hammocks 0.5 SSE

January brought more of the same, but the joy was spread much farther northward. Central Florida, which was very dry during December, received from 125 to 200 percent of normal rainfall. During January the largest departures from normal occurred on the southwest coast of Florida.

Many locations reported in excess of 10 inches of rainfall, and the heaviest rain occurred in Lee County, where five CoCoRaHS observers tallied more than 16 inches of rain during the month. Unlike December the rainfall in January was somewhat more distributed during the month depending on location.

Daily rainfall in January 2016 for CoCoRaHS station FL-LE-5, Lehigh Acres 4.2 WSW.

A number of locations in southern Florida recorded their wettest January on record, breaking old records by 1.5 inches or more.

Graphic credit: NWS Miami, FL

As you might expect, the excessive rainfall caused many flooding problems. Emergency pumping has been initiated in communities near Okeechobee, and the U.S. Army Corps of Engineers has begun to lower the lake by discharging into the Atlantic and the Gulf of Mexico to lessen stress on the lake's dikes. Unfortunately the discharge also contaminates the estuaries along the coasts.

Flooded field in Florida.
Photo credit: Florida Dept of Agriculture
Agriculture is also taking a hit from the heavy rain. Flooded fields and saturated soils have disrupted harvesting activities and the wet conditions promote vegetable disease conditions. Some crops have also been damaged by some of the high winds that have accompanied the storms.

Despite all of the rain in northwestern Florida and the southern half of the state, December-January rainfall remained below normal in the northeastern portion of the state.

After a dry day Tuesday, heavy rain was sweeping across northern Florida today as storms developed ahead of the cold front moving through the state.