NATIONAL WEATHER SUMMARY

 

FEBRUARY 2011

 

1^st-5^th…The potent winter storm that took a 2000-mile trek across the nation during the first half of the workweek to directly affect 30 states finally moved off the New England coast on Wednesday. By late evening, light snow continued to fall across sections of eastern Maine. Farther to the west, scattered lake enhanced and lake effect snow fell across sections of New York State, Pennsylvania and Ohio. However, the intensity and areal coverage of the snow was either diminishing or moving eastward off the New England coast. As of mid-evening on Wednesday, the storm's center was located over the waters of the western North Atlantic off the Cape Sable Island at the southern tip of Nova Scotia. A weak low-pressure center, which was located over Upstate New York near Albany, represented the remnants of the storm center before the system underwent regeneration as it approached the Atlantic Coast. The storm will be long remembered for the heavy snow plus the strong winds that resulted in blizzard conditions across the Midwest. Earlier in the day, the storm had produced locally heavy snowfall from the Great Lakes eastward into sections of the Northeast. In addition to "system" snow (or that snow produced by the storm system), lake-enhanced snow fell as cold winds associated with the storm traveled across the open and relatively warm waters of the Great Lakes. Daily maximum snowfall records were set on Wednesday across the Great Lakes States in Michigan at Grand Rapids (11.1 inches), Lansing (8.4 inches), Flint (8.3 inches), Houghton Lake (7.0 inches) and Detroit (4.3 inches); in Wisconsin at Milwaukee (9.1 inches) and in Illinois at Chicago's O'Hare Airport (6.6 inches). Some stations across Wisconsin and Illinois had received heavy snow on Tuesday and early Wednesday, bringing storm total snowfall accumulations to more than two feet. Farther east, snowfall records for the date were also set Wednesday in New England at Burlington, VT (11.3 inches) and at Bangor, ME (10.7 inches).

A large arctic air mass continued to dominate the weather across a large section of the nation in the wake of the departed winter storm. This arctic air mass accompanied a large and elongated ridge of high pressure that was centered over Nebraska and Kansas on the central Plains. A lobe of this high-pressure ridge extended along the northern Rockies.

The cold dry air produced vigorous nighttime radiational cooling across many locations, especially where snow had recently fallen. More than two dozen low temperature records were either tied or set on Wednesday morning across the West, extending from the high Plains of Nebraska west to California and from Arizona north to Idaho. The air remained sufficiently cold that daytime temperatures remained well below seasonal values. Afternoon high temperatures across the nation's mid-section ranged from 10 to 40 Fahrenheit degrees below the long-term average highs for early February. Some of the largest temperature anomalies (arithmetic differences between observed and average values) were found across the southern Plains, primarily across the Texas Panhandle and Oklahoma. At least 30 stations across the Southwest and southern Plains reported daily low high temperature records for the date. The high temperature of 6 degrees at El Paso on Wednesday represented an all-time record low maximum temperature for any day since temperature records began in the city in 1887.

A line of rainshowers developed on Thursday evening across the Southeast. This precipitation stretched from the Louisiana Gulf Coast northeastward to Georgia and the Carolinas and was associated with a disturbance in the upper tropospheric jet stream flow pattern. To the east, a few scattered thunderstorms developed and were moving to the northeast across northern sections of Florida during the late evening. These thunderstorms formed along and to the north of the cold front trailing from the departed winter storm. After traveling southeastward across the Southeastern States earlier Wednesday, this cold front stalled across the Sunshine State, becoming a stationary front.

More wintry weather gripped the eastern part of the country Friday, but the most extreme weather was confined to the Southeast. A stationary front that stretched from the Gulf of Mexico over the Florida panhandle combined with cold air already in place to produce a mix of rain, snow, and ice from Texas through the Southeast Coast. This precipitation did not move much as the day progressed, thus areas received a significant amount of precipitation. Over an inch of precipitation fell in the Carolinas, while Winter Weather Advisories were posted from Oklahoma through western Ohio in anticipation of more snow. Meanwhile, a few lake effect snow showers were noted in New York, otherwise the Northeast was allowed to dry out. In the West, a few scattered snow showers developed in the Rockies, and precipitation also fell in western Washington. Cold air over much of the country produced some frigid temperatures with afternoon highs of 30s observed in Texas. Florida was on the opposite end of the spectrum with temperature sin the 70s and 80s, while the Northeast

6^th-12^th…The Southeast saw active weather on Monday as two low pressure systems converged over the region. One low pressure system centered itself over northern Mississippi and the other over the panhandle of Florida. These systems created a warm frontal boundary over the Gulf states, while counter-clockwise flow around the system pulled ample moisture onshore from the Gulf. This triggered periods of heavy rainfall with scattered thunderstorm development. Cross City, Florida reported a mid-day rainfall total of 2.22 inches. meanwhile, a cold front extended to the north and tracked northeastward up the Ohio River Valley. This produced a messy combination of snow and rain, with snowfall rates up to 1 inch per hour across Kentucky and Tennessee. Paducah, Kentucky reported snowfall totals between 3 and 8 inches. Behind this system in the Plains, a ridge of high pressure pulled extremely cold air in from Canada. Overnight lows dipped into the negative teens across the Dakotas and Minnesota, while daytime highs remained in the single digits. Windchills ranged from 20 to 30 degrees below zero. Further West, a low pressure system made its way over the Pacific Northwest and into the Northern Rockies and Great Basin. This system triggered periods of low level rain across western Oregon and Washington, while heavy snow showers developed across the mountains. Snowfall totals ranged from 2 to 4 inches across most of the mountains, with more at high mountain passes.

Another round of winter weather pounded the nation's mid-section and Southeast Wednesday. After dumping up to 12 inches of snow in Oklahoma, an inverted trough of low pressure located along the Southern Plains and Lower Mississippi border supported a mix of rain, sleet, and snow development in the Ozarks, Lower Mississippi Valley, and western Tennessee Valley through the afternoon. Arkansas experienced the heaviest amounts of snow as afternoon snowfall rates reached to about 1 inch per hour. Significant wintry precipitation over these regions caused difficult to hazardous travel conditions with slick roads and reduced visibilities. Persistent snowfall also resulted in numerous flight delays and cancellations in Oklahoma during the morning. Winter Storm warnings and Winter Weather Advisories remained in effect from eastern Texas through the Central Appalachians during the afternoon. Meanwhile, on the back of this system, a stable, arctic airmass spread across the Plains and dropped daytime highs to nearly 30 to 40 degrees below average this afternoon. Wind Chill Advisories and Hard Freeze Warnings were issued in Oklahoma and eastern Texas. Elsewhere, quieter weather activity developed across the rest of the nation. In the West, a cold northerly flow and high pressure kept much of the region under dry and chilly conditions during the afternoon. Strong winds of 20 to 30 mph with occasional gusts to 45 mph accompanied a frontal boundary that extended across the freshly snow covered peaks from the northeastern corner of Washington to central New Mexico. This wind and snow combo over the area resulted in a continuation of blowing snow and reduced visibility.

The nation saw relatively quiet weather on Friday as a large ridge of high pressure covered the Plains and East Coast. Temperatures rebounded from the cold spell as the ridge of high pressure weakened. As the ridge flattened out, winds across the Eastern half of the country shifted to more westerly. This cut off the cold, Canadian air and brought more mild temperatures. High temperatures ranged in the 30s across the Midwest and Mid-Mississippi River Valley, while the Tennessee River Valley returned to the 40s. In the North, however, a mild trough of low pressure skirted across the Upper Midwest and Great Lakes. This allowed for cold Arctic air to continue to pour in, while little available moisture triggered light and scattered snow showers. As this system moved eastward over the Great Lakes, the downwind shores saw light lake effect snow showers. Snowfall totals across the Upper Midwest and Great Lakes varied around 1 to 2 inches. Highs in the extreme north remained in the teens with wind chills near zero. In the South, a stalled frontal boundary lingered over the Gulf of Mexico and southern Florida. This allowed for light and scattered rain showers to persist. Mid-day total of 0.26 inches was reported at West Palm Beach, Florida. Out West, a low pressure system in the Gulf of Alaska pushed a front into British Columbia and the Pacific Northwest. This brought cloudy skies with scattered rain showers. Meanwhile, California and the Southwest remained dry and sunny as high pressure dominated.

 

13^th-19^th…The Northeast saw a snowy day on Monday, while rain returned to the West Coast. A low pressure system that developed in the in the Gulf of Alaska has created a strong cold front that finally pushed onshore. This system picked up ample moisture before spreading scattered rain showers over the Pacific Northwest and northern California. High elevation snow developed across the Cascades, but has not yet reached the Sierras. Cold air associated with this system created below normal temperatures and allowed for snow levels to drop to the foothills of the Cascades. This front also brought strong winds as it moved onshore. Whidbey Island, Washington reported gusts up to 57 mph, while Truckee, California reported wind gusts up to 53 mph. Heaviest rainfall developed across Washington with a mid-day total of 1.77 in Quillayute, Washington. Most of northern California saw between a quarter and a half of an inch of rain, except for a mid-day total of 0.66 inches in Santa Rosa, California. In the East, a low pressure system moved from the Great Lakes and into the Northeast. This system brought light and scattered snow showers with it, with snowfall accumulation ranging around an inch in most areas. Parts of Maine saw between 3 to 4 inches of snow. In between these two systems, a ridge of high pressure dominated the Central US, and bought sunny skies with warmer temperatures. Highs reached into the 40s across the Upper Midwest, and approached the 60s in the Central and Northern Plains. Warm conditions returned to the South, with high pressure allowing for highs to reach into the 70s across Texas and Florida.

The western half of the nation saw the most active weather activity in the nation today. A trough of low pressure pushed onshore from the eastern Pacific Ocean and supported precipitation development from the West Coast to parts of the Continental Divide through the afternoon. Waves of energy that trekked through California, Nevada, and Idaho combined with enhanced moist onshore flow to create areas of rain, hail, thunderstorms, high elevation snow, and strong winds across these areas as well as the Pacific Northwest. The West remains under a variety of Winter Storm and Wind Warnings, Winter Weather and Wind Advisories, and other watches, warnings, and advisories. Meanwhile, calm conditions developed over most of the East due to dominant high pressure. Much of the Northeast experienced relatively mild conditions with daytime highs above the freezing mark. Elsewhere, moist flow from the south spread across the Plains and lead to warm afternoon temperatures, increased cloud cover, and chances of rain showers.

The Western US saw more wet and snowy conditions on Friday. A deep and strong low pressure system sitting just offshore of California continued pushing multiple waves of energy onshore. As moisture from the Pacific Ocean continued to feed this system, heavy rain and high elevation snow persisted across most of California. The system has created a 100 mile wide plume of precipitation that stalled over the Sierras and western Nevada overnight, creating snowfall rates up to 1 inch per hour in many areas, with up to 3 inches per hour over the high elevations of the Sierras. By mid-day Friday, the heaviest precipitation shifted southward to the Central Valley and Southern Sierras. Thus, snowfall totals in the Northern Sierras ranged from 2 to 4 inches, up to 8 inches above 7,000 feet, while the Southern Sierras saw up to 21 inches of snow at mountain peaks. Wind advisories have been issued across these regions due to strong and gusty winds, with gusts up to 70 mph across mountain passes. Rainfall totals at lower levels were significantly lower than the previous day, with a mid-day total of 0.50 inches of rain reported at North Bend, Oregon and 0.47 at Monterey, California. Elsewhere across the nation, a low pressure system in eastern Canada created scattered snow showers in the extreme Northeast. The system also produced a cold front that stretched into the Southeast, where it brought cloudy skies which triggered a few light rain showers over the Tennessee Valley. In the Upper Midwest, the back side of this low created strong winds as it moved eastward. Gusts up to 50 and 60 mph were reported across much of Michigan, Wisconsin, and Minnesota.

 

20^th-28^th…Wintry weather hit the Midwest and Ohio River Valley on President's Day, as a low pressure system moved from the Midwest towards New England. The system created a frontal boundary that extended up the Ohio River Valley. Due to warmer temperatures along the southern side of the front, rain developed from Missouri to southern Pennsylvania, while snow developed north of the front over the Lower Great Lakes. Along this front over Ohio and Indiana, saw a messy combination of frozen rain and sleet. Heaviest rainfall hit Bloomington, Indiana with a mid-day total of 1.59 inches of rain. Snowfall accumulation across the Lower Great Lakes ranged from 1 to 2 inches. Just to the north, another trough of low pressure followed close behind this system and sprinkled snow showers over the Upper Midwest. Snowfall accumulation remained light with only 1 to 2 inches in most areas, up to 6 inches in northern Wisconsin. Meanwhile, another low pressure system approached the West Coast on Monday. This system pushed cloudy skies onshore across the Pacific Northwest and northern California. Only a few sprinkles have developed, significant rainfall has not yet been reported. In the central U.S., between these systems, high pressure built in from the North, and allowed for cool air to return. Overnight lows dropped into the negative teens across the Northern Rockies and Northern Plains, while daytime highs barely made it above zero in some places. A mid-day high of 0 degrees was reported in Dickinson, North Dakota.

Another relatively chilly weather day developed across much of the West Wednesday as cold, energetic jets streamed across the Northwest and down the West Coast. Cold northwest flow over the Pacific Northwest and a moist low pressure system over northwestern Washington triggered heavy snow and localized bands of intense snowfall across the state, as well as in parts of northern Idaho and northern Oregon. Periods of snow in Washington and northern Idaho were enhanced by an arctic cold front that dropped southward from the Canadian border. Meanwhile, to the south, cool and dry weather conditions prevailed across California. East of the Rockies, overcast skies covered areas from the Southern Plains through the Mississippi Valley and across much of the Upper Midwest. In the south, low pressure off the southern coast of California continued to advance toward northwestern Mexico and the Southern Plains. This gradual progression provided an increase in southerly flow from the Gulf of Mexico through the Mississippi Valleys and Tennessee Valley, setting the stage for scattered showers and thunderstorms during the afternoon. Meanwhile, to the north, an approaching cold front and trough of low pressure triggered light to moderate snow showers with periods of heavy snowfall to parts of northern Minnesota. Elsewhere, the Eastern Seaboard experienced calm weather conditions.

Active weather persisted across the nation on Friday. Two major winter storms brought wet and snowy conditions to both the East and West Coasts. The system out West slowly tracked down the West Coast, and pushed a strong cold front through California. This triggered periods of heavy rain across Northern California Friday morning, which quickly moved toward southern California. This front also brought periods of heavy snow to the Sierra Nevadas, with snowfall totals from 6 to 12 inches across the northern Sierras. Snow showers diminished across the Cascades, as a mild ridge of high pressure built in to dry out the Pacific Northwest. Strong winds were also associated with this front, with gusts up to 54 mph reported in Truckee, California. The heavy snow and strong winds over the Sierras brought dangerous road conditions with closures at some high mountain passes. Periods of heavy rain developed at lower elevations across northern California Friday morning. Rainfall totals ranged form 1 to 1.5 inches, with up to 1.53 inches in Marysville, California. In the East, a strong low pressure system that brought heavy snow to the Midwest has moved into the Northeast, and triggered more heavy snow. Along the warm front, a messy combination of frozen rain and sleet developed across the New England states. Rainfall totals reached up to 2.05 inches in New Bedford, Massachusetts. Winter weather advisories have been issued through Friday night as heavy snow developed from upstate New York to Maine. Snowfall rates of 1 to 2 inches per hour have been observed at Burlington, Vermont. Mid-day snow accumulation reached up to 8 inches in the extreme Northeast.

A large storm brought snow to the Northeast and produced severe thunderstorms in the Southeast on Monday. The system quickly moved northeastward from the Southern Plains and produced two strong frontal boundaries. A warm front stretched into the Northeast and created periods of heavy snow showers across Maine, as well as northern Vermont and New Hampshire. Total daytime snow accumulation ranged from 4 to 8 inches across these areas. This relatively warm system allowed for rain showers to develop along a cold front that stretched from Pennsylvania, over the Appalachians, and into the Lower Mississippi River Valley. The already moist ground allowed for flooding to be the main concern of this system. Flood advisories have been issued across most of the Ohio River Valley and into Tennessee. Marion, Ohio saw 2.20 inches of rain, with periods of heavy thunderstorms. Elsewhere, rainfall totals ranged from 1 to 2 inches. Strong winds accompanied this front with reports of several trees blown down and damages to houses with roofs blown off near Hardwick, Kansas. Quarter size hail was reported in multiple areas including Pikeville, Kentucky, Gilbert, West Virginia, and Rossville, Georgia. Additionally, a tornado developed in Estill Springs, Tennessee and caused extensive structural damage to residences and multiple trees down. Meanwhile, Out West, another low pressure system pushed over the Pacific Northwest and moved into northern California. This created rain showers with heavy snow showers across the Cascades. Tillamook, Oregon reported a mid-day total of 1.20 inches of rain on Monday. California saw increasingly cloudy skies with areas of light sprinkles, as this system approached from the north.

Jim G. Munley, jr.
http://www.jimmunleywx.com