A MAJOR STORM IN THE NATION'S MIDSECTION -- A large storm system moving eastward from the Plains on Monday affected weather -- in terms of the clouds, precipitation and wind flow -- over much of the country from the Appalachians to the Rockies and from the Gulf of Mexico north into Canada. The storm was responsible for heavy snows across the north, and severe weather in the south. A narrow band of freezing rain also associated with the system was situated between the snow and the rain. As of late Monday night, the low pressure center was located over southern Missouri with a warm front extending eastward and a cold front that stretched southward to the lower Rio Grande Valley in south Texas. This storm system is forecast to continue eastward, with the low pressure center being situated over southern Illinois by dawn on Tuesday morning.
SNOW ACROSS THE CORN BELT -- On Monday night, snow continued to fall over a large area extending northward from central Illinois to northern Minnesota. Through the day, the storm system produced a band of heavy snow from eastern Nebraska across Iowa into Illinois, with a lobe extending northward into southern Minnesota. Amounts ranged from 9 inches in eastern Iowa to 14 inches at Carroll, in the western part of the state. In Minnesota, the Twin Cities received nearly a foot of new snow. The heavy snow is expected to continued eastward through central Illinois into Indiana and Ohio, paralleling the track of the low pressure system. Lighter amounts of snow are expected to reach the Washington, DC-Baltimore, MD area later on Tuesday.
Several ingredients have contributed to the heavy snowfall. Abundant Gulf moisture has been brought northward by southerly winds aloft. Near the surface, a strong easterly flow across the Midwest has brought cold air from the large air mass associated a high pressure cell in eastern Ontario.
However such a situation could pose a problem across the portions of the Southeast. As the precipitation shield approaches the Appalachians in the Virginias and Carolinas, an ice storm could be a possibility as the rain accompanying the southerly flow of warm air falls into the shallow layer of cold air trapped in the valleys between the mountains.
SEVERE WEATHER ACROSS THE SOUTHERN PLAINS -- Severe thunderstorms developed in the "warm sector", located in the warm air situated to the southeast of the surface low, between the warm and cold fronts. Most of the thunderstorms were along a squall line, representing a collection of thunderstorms situated well to the east of the cold front, but parallel to it. Earlier on Monday thunderstorms with heavy rains moved through the Dallas-Fort Worth, TX area and caused localized flooding. Some wind damage also occurred over north Texas. Later on Monday thunderstorms dropped large hail in east Texas and 60 mph thunderstorm winds caused damage in northwestern Louisiana. At least two tornadoes were spawned from thunderstorms in northeastern Oklahoma. Several injuries were reported as a result of these tornadoes.
The thunderstorms were fed by warm, humid Gulf air that was carried northward by low-level southerly winds. Several tornado and severe thunderstorm watches had been issued and subsequently expired in Arkansas and along the Gulf Coast. A slight risk of strong to severe thunderstorms continues across the central Gulf Coast and lower Mississippi Valley through Tuesday morning. This region of greatest risk shifts to the eastern Gulf and the Florida Peninsula by later on Tuesday.
In the warm sector to the south of the cold front, a record high temperature was set at Corpus Christi, TX as the afternoon temperature reached 88 degrees.
CHILLY WEATHER ACROSS THE EAST -- A large ridge of high pressure brought cool and pleasant weather to the East Coast. As of late Monday night, the center of the high pressure cell was situated over James Bay in Canada, with a ridge axis extending southward to the Carolinas. A weak northerly wind flow was found to the east of this ridge axis, while to the west, winds were primarily easterly, feeding into the storm system in the Mississippi Valley.
The cold, dry air mass, coupled with weak winds, clear skies and a relatively deep, fresh snow cover caused record low temperatures to be set Monday morning at Erie, PA with zero degrees and at Rochester, NY with 7 degrees below zero. The record for Rochester was not only a daily record, but also tied the all-time record for the month of March, last recorded in 1885.
The ridge of high pressure is expected to move slowly eastward on Tuesday.
A NEW STORM SYSTEM REACHES THE WEST COAST -- A storm system brought clouds and precipitation to the Pacific Northwest on Monday night. While the low pressure center remained off shore to the west of Vancouver Island, a cold front associated with this storm stretched southward along the Washington, Oregon and northern California coasts. A large region of precipitation in the form of coastal rain and high elevation snow extended from Puget Sound south to the central valleys of California south of San Francisco Bay. By late afternoon, at least four inches of snow and high winds to 64 mph were reported in the Siskiyous in northern California.
The cold front is forecast to move across the Sierras into the Great Basin by early Tuesday morning. A wide area of precipitation, especially in the form of snow, is anticipated to expand eastward across the West. Winter storm warnings were posted for the central Sierras.
TEMPERATURE EXTREMES IN THE LOWER 48 -- The lowest temperature in the lower 48 states on Monday was 22 degrees below zero at Saranac Lake, NY and Monday's highest temperature was 94 degrees at Alice, Laredo and Kingsville, TX.
ALASKAN WEATHER -- A ridge of high pressure centered over the Chuckchi Sea extended southeastward across western Alaska. Relatively cloud-free skies were reported from the North Slope southward across the Seward Peninsula, Kodiak Island and portions of interior Alaska. Overnight temperatures for many locations across the north fell to 30 degrees below zero or lower. A storm system over the Bering Sea spread clouds and rain across the Bering Sea and coastal portions of western Alaska. Clouds associated with the front that stretched eastward from the low pressure system had reached the coast of the Yukon-Kuskokwim Delta, Bristol Bay and the Alaska Peninsula. To the west of the front, partly cloudy skies returned to the western Aleutians. Windy conditions also accompanied this system, with strong wind gusts reported at Cape Romanzof, Cold Bay and St. Paul Island. Another storm system was essentially stalled in the northern Gulf of Alaska to the south of Cordova. This system was responsible for the cloud cover and light snow found across the north Gulf coast, southeast Alaska, to include the Copper River Basin.
On Monday the overnight lowest temperature in the state was 44 degrees below zero at Nuiqsut Airport, while the midafternoon highest temperature in Alaska was 39 degrees at Annette.
HAWAIIAN WEATHER -- A large ridge of high pressure located to the northeast of Hawaii on Monday afternoon was responsible for moderate trade winds ranging between 10 to 25 mph, together with associated trade weather over the islands. A cloud band associated with a weak shear line was expected to move across the islands on Monday night and into Tuesday morning with some showers. Winds should become more northeasterly. While most of the weather should be fair following passage of the cloud band, light showers could be expected to continue over the windward slopes of the islands. This pattern was expected to continue through mid week.
THE WATER BUDGET -- For more information describing the global hydrological cycle, you may consult the optional material in Tuesday's electronic 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, 1999, The American Meteorological Society.