Today is President's Day, a Federal holiday serving to commemorate the February birthdays of Presidents George Washington and Abraham Lincoln.
WEATHER OVER THE WEEKEND -- A winter storm that moved from the Southern Plains through the Ohio Valley and Great Lakes States into the Northeast at the start of the weekend created numerous weather-related problems for many residents from the lower Mississippi Valley into the northeast quadrant of the country. On Thursday evening the center of the storm was located in the Texas Panhandle and by Friday evening the low pressure center had moved to the northeast to the Ohio Valley near Cincinnati, OH. During the next 24 hours, the storm continued to move eastward and had essentially moved off the New England coast by Saturday evening. As of Sunday morning, only some lingering lake-enhanced light snow and snowshowers continued to fall downwind of Lake Ontario across Upstate New York and New England as winds turned westerly.
The storm developed along a region of temperature contrast between seasonably cold air across the northern tier of states and unseasonably warm air along the Gulf Coast. Jackson, MS had a record high minimum temperature of 67 degrees on Friday morning. Record high temperatures were either tied or set on Friday afternoon at Mobile, AL (80 degrees), Tupelo, MS (79 degrees), Galveston, TX (78 degrees) and in Louisiana at Monroe (83 degrees) and Audubon Park in New Orleans (82 degrees), while on Saturday a record high temperature was set at Tallahassee, FL (86 degrees).
The counterclockwise circulation of air around the storm helped push warm, moist air northward on the east side of the storm, with a warm front extending to the east of the low center. Colder air was transported southward on the west side of the storm, behind a cold front that trailed southwestward from the low center. The southerly flow of humid air from the Gulf of Mexico also supplied much of the moisture needed to produce the fairly substantial precipitation along and to the north of the warm front in a large region from the southern Plains into the Ohio Valley at the start of the weekend.
On the cold north side of the storm, a band of heavy wet snow fell by late Friday afternoon along a region from western Iowa into the lower Michigan. Almost 10 inches of snow were reported on the ground near Rock Island, IL while Grand Rapids, MI received 5.5 inches of snow, a daily record snowfall for the date. By Saturday as the storm moved northeastward, between 5 to 10 inches of snow fell across the higher terrain of Upstate New York and interior New England.
In the warm air closer to the storm, between 2 and 6 inches of heavy rains fell across a large area of the Ohio Valley for much of Friday. Evansville, IN received 3.38 inches of rain on Friday, which not only set a daily rainfall record, but was also the wettest February day on record for that city. Some large hail was also reported as a result of thunderstorms. Flash flooding also occurred in the area. Farther upstream, tributaries to the Upper Ohio River in Pennsylvania, West Virginia and Ohio flooded late Friday and remained at or above flood stages into Saturday. A state of emergency was declared in 10 West Virginia counties and at least two people were killed near Charleston, WV as a result of the flash floods. As warm air was carried into the Middle Atlantic states, some areas across Pennsylvania, Maryland and Virginia saw the snow change to first to ice pellets (sleet) and freezing rain before finally changing to rain as warm air with rain rode over shallow layers of cold, subfreezing air trapped near the earth's surface.
A large warm and humid air mass located to the south of the storm was sufficiently "unstable" to permit explosive thunderstorm development. Numerous thunderstorms, some of which turned severe, developed in the "warm sector" of the storm, defined as the region usually located to the southeast of the low center in the region bounded by the warm and cold fronts. These thunderstorms that formed an extended line ahead of the cold front contained large hail and produced damaging high winds across portions of east Texas, northern Louisiana, northern Mississippi and west Tennessee on Friday afternoon. Several tornadoes were reported across Arkansas and Mississippi, to include tornadoes that caused injuries and property damage on Friday afternoon near Little Rock, AR. According to the National Weather Services' Storm Prediction Center, 35 hail reports, 12 wind reports and 15 tornado reports were filed on Friday. Some thunderstorms formed ahead of the cold front as it passed across the Carolinas and Virginia on Saturday morning, but none became severe.
Cool high pressure pushed southward across the Plains in the wake of the storm system. The high pressure system that was located over eastern Montana on Thursday night and Friday morning pushed south-southeastward across the Plains behind the cold front that trailed the storm system. By Sunday morning this high pressure center was located across the southern Plains and Lower-Mississippi Valley. As a result, a large portion of the country experienced relatively cloud-free and tranquil weather on Sunday. With warm southwesterly winds and a lack of local snow cover, Grand Forks, ND had a record high temperature of 52 degrees on Sunday afternoon. Temperatures at neighboring locations with snow cover only reached the low 30s.
The weather along the West Coast for the start of the weekend was remarkably tranquil with few clouds in contrast to the string of storms that had dumped flooding rains across central California earlier last week. A large ridge of high pressure was located over the Pacific Northwest. A storm system moved slowly southeastward across the eastern North Pacific Ocean but remained a sufficient distance offshore for the first half of the weekend. Along the southern California coast, a weak offshore flow produced a warm Saturday across the region with record high temperatures set at Newport Beach Harbor (81 degrees) and Oceanside Harbor (79 degrees). By Sunday morning a large region of precipitation spread across California in advance of an approaching storm system. Some thunderstorms moved across portions of central California near San Luis Obispo and Santa Maria early Sunday evening. Some locations received more than 2 inches of precipitation by early Sunday evening. This rain was well received, since little rain had fallen across southern California during this normally wet time of year.
Over the weekend several avalanches in the Northeast proved deadly. Strong winds coupled with heavy snows from the weekend's snow produced conditions ripe for avalanches. On Saturday, an avalanche killed a skier and injured five others on the northeast slopes of Wright Peak, just outside Lake Placid, NY. On Sunday afternoon, at least one skier was killed on the north face of Mt. Washington, NH, while another skier who was partially buried escaped major injury. At the time, the Mt. Washington Observatory on the summit reported winds of 58 mph with gusts to 64 mph, visibility of 1/16 of a mile in blowing snow and freezing fog.
WEATHER FOR STARTING THE NEW WEEK -- Much of the eastern half of the nation experienced relatively quite weather on Sunday night the result of a large, sprawling high pressure that was centered over the lower Mississippi Valley. The major exception to the settled weather was the region downwind of the eastern Lakes. Lake-effect snow continued across portions of Upstate New York downwind of Lake Ontario winds remained out of the northwest direction. The quiet weather was well received by residents of the Ohio Valley, as flood waters were beginning to recede.
High pressure is predicted to maintain its influence across the East on Presidents Day. With high pressure expected to be centered over the Cumberland Plateau of east Tennessee, northwesterly winds should continue across the eastern Great Lakes. A lake-effect snow warning was continued for Upstate New York, with heavy accumulations along the Mohawk Valley.
In the West, a large area of precipitation continued across most of California on Sunday night. Coastal and valley rain along with mountain snow were the result of a cold front that had moved onshore on Sunday. This cold front was associated with a storm system located approximately 200 miles off of San Francisco's Golden Gate and curved eastward into the San Joaquin Valley near Sacramento and then southward, exiting off the coast near Los Angeles. The system was entraining cold air, resulting in thunderstorms and lowered snow levels. Farther north, precipitation fell along the coasts of both Oregon and Washington in association with a north-south running stationary front that was located just off shore.
This storm system is expected to move inland on Monday morning and by evening, the low pressure center was predicted to be located over the Great Salt Lake Basin of Utah. The area of precipitation accompanying this system should spread across the Intermountain West. Because of the relatively heavy rains of Sunday, flood watches and warnings were also in effect for much of Southern California, especially in the burn areas of the Los Angeles Basin and near San Diego, where mudslides could also develop. Snow levels were expected to descend to below 4000 feet in Southern California, with snow accumulations of nearly a foot between 5000 and 8000 feet. To the east, a variety of winter storm warnings and watches have been posted for the mountains of Nevada and northern Arizona.
Because of the large westerly ocean swell generated by the strong Pacific storm, a heavy surf advisory was in effect for the coastline of southwest California through Tuesday night from the vicinity of Point Conception south toward San Diego.
TEMPERATURE EXTREMES IN THE COTERMINOUS U.S. -- The lowest temperature on Sunday was 17 degrees below zero at Presque Isle, ME and West Yellowstone, MT. Sunday's highest temperature was 84 degrees at Opa Locka, FL.
ALASKAN WEATHER -- A storm moving to the east-southeast across the southern Bering Sea toward the western tip of the Alaska Peninsula on Sunday was accompanied by clouds and precipitation that spread across western Alaska. A fairly strong pressure gradient to the north and west of the storm produced strong winds across the Bering Sea and the central Aleutians. Blizzard warnings were posted for the Bering Strait and along the Lisburne Peninsula, to include Point Hope. Several other weak troughs of low pressure were located across southern Alaska. An arctic front along the Brooks Range represented the boundary between cold air with strong easterly winds along the North Slope from warmer air to the south. Point Lay had a wind-chill equivalent temperature of 80 degrees below zero on Sunday. Snow fell at Kotzebue, Bettles, Bethel, Kenai and Valdez on Sunday morning, while rain fell at Homer, Seward, Whittier and across the Panhandle. In the 24 hours ending on Sunday afternoon, Annette had 1.27 inches of liquid equivalent precipitation (rain and melted snow) and Yakutat had 1.26 inches.
The lowest temperature in the state as of Sunday morning was 35 degrees below zero at Umiat, while the midafternoon state high on Sunday was 42 degrees at Sitka.
HAWAIIAN WEATHER -- High pressure located to the northeast of Hawaii produced relatively cloud-free skies with northeast trade winds across the islands on Sunday afternoon. Some nighttime showers were anticipated. An increase in wind speeds along with some additional clouds are expected on Monday as another high pressure cell moving toward the east passes north of the islands. On Saturday, the surf on the west and north facing sides of the islands rose to 20 feet or more, the result of storms in the western Pacific that generated ocean swells. High surf warnings were continued along the north and west facing shores of the islands.
BECOMING AWARE -- During this coming week of 20-26 February, the following states across the South have scheduled their Severe/hazardous Weather Awareness Week: Alabama, Arkansas, Florida, Georgia, Louisiana, Mississippi, North Carolina, South Carolina and Tennessee. These weeks are usually scheduled before the typical onset of the severe weather season. If you live in any of these states, you should take time to become familiar with the various public affairs announcements issued by your local National Weather Service Office. Other states farther to the north will be observing their Severe Weather Awareness weeks in the next 6 weeks.
SO WHAT IS A METGRAM OR METEOROGRAM? -- Learn how to interpret the meteorograms that you can access for selected cities from the Online Weather Studies Prject from Monday's optional Supplemental Information .
From the files of the Aviation Weather Center, Kansas City, MO and Intellicast
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Prepared by Edward J. Hopkins, Ph.D., email hopkins@meteor.wisc.edu
© Copyright, 2000, The American Meteorological Society.