WEATHER OVER THE WEEKEND -- The Midwest and the Middle Atlantic states were struck by several bouts of severe weather over the weekend. These severe weather episodes were associated with at least three storm systems that tracked eastward in rapid succession. A distinct thermal contrast between the abnormally cold weather in the West and warmer conditions over the Southeast helped maintain unsettled weather conditions.
Just before daybreak on Friday morning, severe thunderstorms spawned a killer tornado that killed four in Hamilton County Ohio, to north of Cincinnati. Roughly 100 injuries were reported. These thunderstorms were in the warm sector to the southeast of a storm system that moved eastward from the Plains late Thursday night. This system had a history of producing severe weather. Numerous reports of large hail, damaging wind and tornadoes had been made from Illinois and southern Indiana earlier that night. Two people were killed by the damage produced by the thunderstorm winds in central Illinois. The thunderstorms traveled eastward along the Ohio Valley into Pennsylvania as the parent storm system continued its eastward move from northern Illinois on Friday morning to Maryland by evening. Wind damage and large hail were reported in Ohio, Maryland, Virginia and New Jersey on Friday afternoon and evening. A possible tornado that caused some damage was reported on the Virginia Cape. By Saturday morning, the parent storm system was well to the southeast of the Gulf of Maine.
Strong non-thunderstorm winds continued over the Colorado Rockies and along the Front Range from Friday afternoon through Saturday morning. Gusts reached 75 mph on Friday at Alamosa and on Saturday morning, Walsenburg reported a 89 mph gust, while a 79 mph was recorded at Fort Carson. These winds were associated with the next storm system that had moved eastward from the Pacific Coast and crossed the Rockies by Friday evening. Between one and three feet of new snow were reported in the Big Horns of Wyoming by Saturday afternoon. During Saturday this storm intensified over the Nebraska Panhandle and moved eastward. By Saturday night a complex storm system with two low pressure centers was located over the Mid-Mississippi Valley. Thunderstorms that developed to the east of this system produced hail and high winds across Illinois, Indiana and into southern Ohio starting on Saturday afternoon and running until late Saturday night. Additional reports of severe weather came from Tennessee and Arkansas. On Sunday, severe weather associated with thunderstorms associated with the storm, moved through West Virginia, Pennsylvania and New York State. During the afternoon, several unconfirmed tornadoes were reported across eastern portions of North Carolina. High winds blew a circus tent down and injured eight people on Roanoke Island. Thunderstorm winds gusted to 104 mph at the Oregon Inlet in Dare County along the Outer Banks. Numerous waterspouts were reported over Pamlico Sound. To the north and west of the parent low pressure system, lake-enhanced rain and snow fell across Michigan on Sunday. Thundersnow was reported. As much as seven inches of snow fell on Sunday in lower Michigan. Several inches of snow were also reported across portions of central and northeastern Wisconsin. Heavy rain fell across New York and Pennsylvania on Sunday afternoon, with a change to snow across portions of Upstate New York.
The next storm system moved onto the coast of Oregon and Northern California on Saturday morning before moving to the southeast, reaching Southern California by early Sunday. Wide spread rains were brought along with system as it moved southward toward Los Angeles. As much as 1.50 inches of rain fell on Sunday afternoon at one location in Long Beach, with other locations in the Los Angeles Basin receiving nearly an inch of rain. These rains produced some localized flooding and caused the first rain-out of a Los Angeles Dodger baseball game at Dodger Stadium in more than 10 years.
Over the weekend, numerous daily record high temperatures were set across the Gulf Coast States and the Southeast. Record high temperatures in the lower 90s were recorded at several locations in Florida, to include Orlando, on Sunday.
On the other hand, a cold air mass continued to produce record low temperatures across the Pacific Northwest and southward through California's central valleys into the Los Angeles Basin The Sacramento and northern San Joaquin Valleys experienced frosty conditions on Friday and Saturday mornings. Several locations in Utah's Great Basin also reported record low temperatures on Saturday morning.
WEATHER FOR STARTING THE NEW WEEK -- As of late Sunday night, one storm system continued to produce unsettled weather and precipitation along the East Coast, while two storm systems were influencing the weather along the West Coast. Elsewhere, a large sprawling ridge of high pressure located over the central Plains, from northern Kansas to southeastern Saskatchewan was responsible for relatively tranquil, and cool weather across much of the central portion of the country.
The storm system in the East was a complex low pressure system that was situated over the Middle Atlantic States. One low pressure center was an old, dissipating low that situated over western Pennsylvania. The primary low pressure center that had developed as part of the older storm system and was now located to the east of Hampton Roads, VA. This low had a cold front that extended along the Eastern Seaboard, before turning west over Georgia to parallel the Gulf Coast, becoming a stationary front over south Texas. Areas of precipitation associated with these two low pressure centers were found from coastal North Carolina, where the risk of severe thunderstorms continued through much of Sunday night, into the mountainous areas of southern New England, western New York State and Pennsylvania, where light snow was forecast. By Monday morning the primary low is expected to be well out to see, while the dissipating low should move toward the eastern Pennsylvania. Light precipitation should continue across the Middle Atlantic States and southern New England through Monday morning.
Along the West Coast, a complex low pressure system continued to bring widespread precipitation to Southern California. One low center remained along the Southern California coast near Los Angeles, while a second low was situated to the east-northeast over the lower Colorado River Valley near Las Vegas, NV. As of Monday morning, a low pressure center is forecast to be located along the Colorado River near Blythe, CA. A region of widespread precipitation is expected to expand northeastward into the Four Corners area with continued low-elevation rain and high-elevation snow across Southern California. A variety of snow advisories and winter storm warnings remained in effect for snowfall of as much as 8 inches in the mountains near San Diego. Later Monday, when this storm system moves eastward, the threat of strong to severe thunderstorms should increase over the southern Rockies and into eastern New Mexico and west Texas.
Farther north in the Pacific Northwest, an approaching cold front was expected to produce precipitation across Washington State's Olympic Peninsula by Monday morning. This cold front trails from a storm system located in the northern portion of the Gulf of Alaska. With warmer weather, rivers across southern Oregon and northern California are beginning to rise rapidly toward flood levels as the large snowpack in the mountains begins to melt.
UPPER AIR -- The 500-mb and 300-mb charts for 00Z Monday continue to show a large pool of air over the West Coast. Both charts have a large height trough along or to the west of southern California. These regions where the respective constant pressure surfaces have the lowest altitude, reflect the cold air column of air in the lower to mid troposphere that brought snow to the mountains of Southern California. Another height trough appears on both charts over the eastern Great Lakes. This trough is associated with the cool air and the surface low pressure system that brought snow to the lower Lakes and into the mountainous areas of Pennsylvania, New York and New England.
A strong jet stream at 300 mb runs from the southern California across the southern Rockies, the central Plains and toward the Middle Atlantic States. Winds reached 130 knots over the Mid-Mississippi Valley.
TEMPERATURE EXTREMES IN THE COTERMINOUS U.S. -- The lowest temperature on Sunday was one degree below zero at West Yellowstone, MT. Sunday's highest temperature was 95 degrees at Pompano Beach, FL.
ALASKAN WEATHER -- A low pressure system was located near Prince William Sound together with an occluded front that ran along the Gulf coast south to the Queen Charlottes, where a cold front extended south-southwestward across the eastern Pacific Ocean. A trough line extended westward from the low center toward the Yukon-Kuskokwim Delta. This low pressure system spread clouds and precipitation along the Gulf Coast and across most of the Panhandle. Sitka received one inch of rain since midnight on Sunday morning, while Annette, Yakutat, Juneau, Cordova and Valdez got smaller amounts. A stationary frontal band extended from east to west across the state along the Yukon River. This front separated warm air with temperatures in the 30s and 40s across southern Alaska from the colder air with subzero temperatures that remained mainly to the north of the Brooks Range, even into Sunday afternoon.
The lowest overnight temperature across the state on Sunday was 17 degrees below zero at Wainwright. The state's highest midafternoon temperature was 45 degrees at Eielson AFB/Fairbanks.
HAWAIIAN WEATHER -- Strong trade winds continued to dominate the islands' weather over the weekend as a large ridge of high pressure remained relatively stationary to the north-northeast of Hawaii. The central pressure of this high was 1034 mb as of late Sunday afternoon. Some heavy trade showers also continued on the windward slopes of the islands. As much as 2 to 5 inches of rain fell over Hilo and the Puna Districts of the Big Island during the 24 hours ending on Sunday afternoon. A slackening of the winds and a diminishing of the showers are expected by Tuesday as the high pressure system appears to weaken. Gale warnings remained in effect over the weekend for the channels east of Molokai, while small craft advisories were continued for the remaining waters.
BECOMING AWARE -- During this coming week of 12 -16 April, Idaho and Washington State will conduct their Severe/Hazardous Weather Awareness Week. These weeks are usually scheduled before the onset of the severe weather season in that particular state. 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. In upcoming weeks, other states will observe Severe Weather Awareness weeks.
HAZARDOUS HIGHS -- We usually associate low air pressure with stormy weather and high pressure with "fair weather", a somewhat subjective term used to describe pleasant weather conditions, with no precipitation and few clouds. But can high pressure deliver "un-fair" weather? For a description of the types of hazardous weather associated with high pressure systems, please check 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, 1999, The American Meteorological Society.