SEVERE WEATHER CONTINUES ACROSS THE SOUTHERN PLAINS -- Following Monday's deadly tornado outbreak that slammed the Plains from Texas through Oklahoma, Kansas and Nebraska, the focus shifted eastward and southward as more severe thunderstorms spawned tornadoes on Tuesday. As of late Tuesday night, tornadoes had been reported in east Texas, northwest Louisiana, eastern Oklahoma and in both central and northeastern Kansas.
During the day, a tornado that crossed Titus County in northeastern Texas, caused one fatality, while another tornado caused major damage and 11 injuries in De Kalb, while a third tornado produced 3 injuries in Kilgore. Severe thunderstorms also produced large hail and wind damage in the Dallas-Fort Worth metropolitan area during the afternoon, as well as in Louisiana and southwestern Missouri. Thunderstorm winds gusted to 80 mph in east Texas, causing wind damage. Following Monday's tornadoes, Oklahoma City had thunderstorms that produced large hail early Tuesday. Farther east, hail reports were made during the afternoon from Mississippi. Isolated thunderstorms with large hail were reported across North Dakota and northern Minnesota.
In addition to the hail, high winds and tornadoes, heavy rain fell, producing flash floods. Many locations in Missouri as well as portions of adjoining states were flooded. As of early evening, Springfield, MO had received a record 2.45 inches of rain for the day.
The severe weather outbreak was associated with a storm system in the central Plains. A low pressure system was located in south central Nebraska, along a frontal zone that separated warm tropical air to the south and east from cooler air to the west. A stationary front extended northward from the low pressure center to the Manitoba Lakes region, while a cold front curved southwestward over north Texas and into southern New Mexico. A broad area of precipitation spiraled in toward the low pressure center. Bands of rain and thunderstorms stretched from the Alabama Gulf Coast northward to the Upper Mississippi Valley. Satellite and radar imagery on Tuesday night showed that several supercellular thunderstorms were located just offshore of Mobile, AL and Pensacola, FL. Some of the severe weather, to include the tornadic thunderstorms that moved across northeast Texas had formed along a dry line that represented the leading edge of relatively dry air that moved eastward replacing humid air. This dry line was out ahead of the cold front.
The storm system is expected to move eastward as the low pressure system undergoes an occlusion process by Wednesday morning. A warm front should stretch across the upper Mississippi Valley as southerly winds carry warm, humid air northward. An area of warm frontal rain should be found from southeast Minnesota to central Indiana. The cold front should move eastward into Iowa and Missouri.
WARM WEATHER ACROSS THE EAST -- Much of the East experienced southerly winds and relatively sunny skies associated with high pressure. Afternoon high temperatures across portions of the Midwest were approximately 15 degrees above the climatological average high for this time of year. Record high temperatures were reported in Corpus Christi (100 degrees) and Brownsville, TX (99 degrees), Muskegon, MI (83 degrees), Caribou, ME (85 degrees).
On the other hand, high pressure with weak winds, clear skies and a relatively dry air mass allowed overnight low temperatures to fall to record lows in central Florida at Melbourne (51 degrees) and Orlando (53 degrees).
COOL WEATHER CONTINUES ACROSS THE WEST -- Much of the West was abnormally chilly as cold air continued across much of the West on Wednesday. Afternoon high temperatures ranged between 10 and 15 degrees colder than the corresponding climatological average high temperatures. Heavy snow was reported in the Oregon Cascades, with 28 inches of snow falling at Timberline Lodge on Mt. Hood between Sunday night and midday Tuesday.
A snow advisory for as much as 6 inches was posted for the central Colorado mountains. Cool dry air is expected to expand eastward across the western Plains on Wednesday.
A PESKY STORM CONTINUES OVER NEW ENGLAND -- A low pressure system that produced chilly, wet weather over the Southeastern and Middle Atlantic states from the end of last week continued to spin offshore on Tuesday. The position of the low pressure system was located off the New Jersey coast. A precipitation shield associated with this storm system remained over New England, stretching westward to the Champlain Valley of Upstate New York. This rain is welcome since interior New England has experienced abnormally dry conditions.
This system is expected to move toward Cape Cod by Wednesday, and the accompanying precipitation should begin to diminish over northern New England.
UPPER AIR -- The upper air charts for 00Z Wednesday indicate a large height trough has moved slowly eastward to a position over the Rockies and the western Plains. The axis of the trough is oriented in a northwest-southeast direction, extending from the Canadian Rockies to the Texas and Oklahoma Panhandles. A large height ridge is situated over the Great Lakes extending southward to the eastern Gulf Coast. As a result, strong southerly winds continue at both the 500 mb and 300 mb constant pressure levels. A strong 300 mb jet streak is found over Oklahoma with winds in excess of 100 knots. In addition, the spreading of the height contours and the observed winds downstream of the base of the trough contributes to upper tropospheric divergence and uplift. Such a pattern is important in the development and maintenance of severe weather events, such as those that moved across the Southern Plains on Monday and Tuesday. The trough also indicates a cold pool of air over the West. The intrusion of cold air aloft into the southern Plains helps to destabilize the atmosphere, enhancing convection. A clockwise turning of the winds with height over the east Texas, Louisiana and Arkansas would help initiate the spin needed for formation of the tornadic thunderstorms.
TEMPERATURE EXTREMES ACROSS THE LOWER 48 -- On Tuesday, the lowest temperature reported in the continental U.S. was 18 degrees at Stanley, ID, while Tuesday's high was 110 degrees at McAllen, TX.
ALASKAN WEATHER -- A large complex region of low pressure was located over northeast Gulf of Alaska and southeast Alaska on Tuesday afternoon. One low pressure center was situated near Anchorage, with a trough line that extended eastward along the Gulf coast. Another low was located farther south over the Gulf. Clouds and light precipitation were found over the Panhandle and Southeast Alaska. A large ridge of high pressure was centered over the Arctic Ocean to the north of Point Barrow. A second high pressure ridge was located over the western Aleutians and the Bering Sea. As a result of the pressure gradient between these high pressure systems and the region of low pressure in the Gulf, brisk easterly winds were found along the Arctic coast, while strong northerly winds were found over coastal regions of western Alaska. A wind advisory remained in effect for Cold Bay. Snow fell across the Yukon-Kuskokwim Delta, Bristol Bay and the Alaska Peninsula. The northwest winds produced blowing snow conditions that reduced visibility at Bethel and Cold Bay. Snow and fog were reported at King Salmon.
The lowest overnight temperature in the state on Tuesday was 4 degrees below zero at Nuiqsut and Barter Island, while the midafternoon highest temperature was 53 degrees at Palmer.
HAWAIIAN WEATHER -- Light southeasterly winds continued to be found across the islands as a ridge of high pressure remained to the northeast of Hawaii. As a result of the weak winds and the increased humidity, afternoon convection over the interior portions of the islands should produce clouds with widely scattered light showers. The ridge is expected to approach the islands with winds over Kauai and possibly Oahu shifting to a more southerly direction on Wednesday.
MORE ABOUT MONDAY'S TORNADO OUTBREAK -- The tornadoes that moved across the Southern Plains on Monday afternoon and evening were responsible for 43 fatalities, hundreds of injuries and thousands of homes destroyed or badly damaged. As many as 76 separate tornado reports were filed at the Storm Prediction Center. This tornado outbreak was the deadliest in last 52 years in the state of Oklahoma. The hardest hit area was Bridge Creek, a southwestern suburb of Oklahoma City, where 11 people were killed in the path of an estimated F-5 tornado that may have traveled over 60 miles from west of Chickasha through Moore and Midwest City. Five people were killed by a tornado that traveled 12 miles through southern Wichita, KS and suburban Haysville. The National Weather Service Forecast Office at Norman, OK has posted information on the Oklahoma killer tornadoes of 3 May 1999 at http://www.nssl.noaa.gov/%7Enws/.
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.