SEVERE WEATHER ACROSS THE SOUTH CENTRAL STATES --A low pressure system that moved slowly northward on Monday was accompanied by severe thunderstorms that moved eastward from Texas to Mississippi. To the north of this system, heavy rain created flooding problems. As of late Monday night the low pressure center was located over southwestern Missouri. An occluded front was located to the south of the low to a point of occlusion over Arkansas, where a warm front extended eastward along Tennessee Valley. A cold front trailed southwestward and then westward from the point of occlusion, crossing north Texas and running west to New Mexico. An extensive precipitation shield extended around the northern quadrants of the low, from western Tennessee to central Kansas, and north to southern Iowa. A weakening line of thunderstorms was located to the east and south of the low, extending from Tennessee southward through western Alabama to near Mobile Bay.
A bowed line of severe thunderstorms moved eastward across the Gulf Coast States on Monday, accompanied by heavy rain, large hail, damaging winds and several tornadoes. This line of thunderstorms formed on Sunday night and by Monday morning it stretched from central Oklahoma to south Texas as it passed through the San Antonio and Dallas-Ft. Worth metropolitan areas during the morning rush hour. Winds reached 40 mph in San Antonio and 62 mph in Arlington, located between Ft. Worth and Dallas. Wind damage was reported in Waco, Dallas and other communities across north Texas. Several tornadoes were reported east of Dallas. Both Dallas and San Angelo reported flooding as a result of the excessive rain. At midday, damaging winds gusted to 100 mph at Marshall, in northeast Texas near Longview, and Shreveport, LA had gusts to 75 mph. A thunderstorm gust that reached 97 mph caused damage near Magnolia in southern Arkansas. A cooperative observer in west central Arkansas reported one half inch of rain in 12 minutes. By late afternoon, the squall line crossed the Mississippi. At least one injury was sustained by a possible tornado in northwestern Mississippi late Monday afternoon. Later in the evening the line began weakening by the time it reached Tupelo, MS. In addition, several tornadoes were reported late Monday afternoon near Harlingen in the lower Rio Grande Valley.
Another round of severe weather formed on Monday night in the southern Plains as several severe thunderstorms developed over southern Kansas, where at least one tornado was reported near Wichita, and across central Oklahoma, where hail with diameters exceeding one inch in diameter fell from these thunderstorms. Severe thunderstorms were also reported across the Texas Panhandle.
The heavy rain that fell across Missouri, Kansas and Oklahoma on Sunday continued into Monday. As a result of the persistent and sometimes heavy rain, flooding occurred on many rivers.
The low pressure system is expected to continue moving northward into central Missouri by Tuesday morning. The precipitation shield should also move northward, encompassing much of Iowa and Missouri, as well as portions of eastern Kansas, central Illinois, southern Indiana and Kentucky. The region with the threat of possible severe thunderstorms is expected to extended over the lower Mississippi and Ohio valleys.
COOL WEATHER ACROSS THE NORTHEAST -- A cold front moved across New England and Upstate New York on Monday. This front was associated with a low pressure that was over the Gulf of Maine as of Monday night. Cool northerly winds and scattered precipitation were found behind the cold front. Showers are expected to continue across Maine into Tuesday.
A COLD FRONT MOVES ACROSS THE NORTHWEST -- A cold front that entered the Pacific Northwest on Sunday continued its eastward progress across the northern Montana Rockies. As of Monday night the cold front trailed from a low pressure center over Saskatchewan southwestward across Montana, to a second low in Idaho and then to southern California. Some widely scattered rain and high elevation snow fell across the region. This system is expected to move eastward by Tuesday, with widespread light precipitation found particularly along the Continental Divide in the north, and into the Great Basin across the south.
MUCH NEEDED RAIN -- Several thunderstorms moved across the parched Florida Peninsula on Monday. Some of these thunderstorms turned severe as large hail fell in Orlando, and golfball-sized hail, together some damage, were reported southwest of Lake Okeechobee. One to two inches of marble sized hail accumulated on the ground near Lake Placid south of Orlando. However, wildfires continued to be a major problem across the Sunshine State. Reduced visibility due to smoke from wildfires closed the Florida Turnpike in St. Lucie County near Fort Pierce on Monday. Conditions also remained warm. The afternoon high temperature of 93 degrees at Lakeland tied the daily maximum temperature record.
UPPER AIR -- Both the 500 and 300 mb constant pressure charts for 00Z Tuesday show a meridional oscillation with a large north south excursion, especially across the Plains. The onshore winds encounter a ridge across the West, requiring a slight deflection to the north, before they turn southward as they move along the west limb of the height trough along the eastern slopes of the Rockies. Rounding the base of the trough, winds are northerly along the east limb of the trough over the Mississippi Valley. A ridge is found over the eastern Lakes. The height trough on the two pressure surfaces is related to the surface low pressure feature.
TEMPERATURE EXTREMES IN THE LOWER 48 -- The lowest temperature in the lower 48 states on Monday was 21 degrees at Alamosa, CO, while Monday's highest temperature was 98 degrees at McAllen, TX.
ALASKAN WEATHER -- A ridge of high pressure centered over the Arctic extended southward over Bristol Bay. As a result, relatively clear skies were found across central and interior Alaska, the Alaska Peninsula, Kodiak Island and the Kenai Peninsula. Along the western flank of the ridge, clouds increased over the lower Yukon Valley and western Alaska. Clouds were also reported in the Tanana Valley. Snow fell in the interior such as near Eagle, Galena and along the west coast at Unalakleet. A weakening elongated trough of low pressure remained stationary over the northern and eastern Gulf of Alaska spread clouds along the adjacent coast from Prince William Sound east and southward to the Queen Charlottes. Earlier on Monday, rain fell along the Panhandle. Windy conditions were found at Whittier with gusts to 35 mph and at Gambell with gusts to 33 mph. A storm system was also located over the North Pacific just south of the central Aleutians. Clouds from this system were found across the Aleutians.
The lowest overnight temperature in the state as of Monday was 20 degrees below zero at Ugnu-Kaparuk. The highest midafternoon temperature in Alaska was 51 degrees at Klawok.
HAWAIIAN WEATHER -- A large ridge of high pressure situated to the northeast of Hawaii maintained light to moderate trade winds across the islands on Monday. This subtropical circulation feature should continue through the first half of this week. Trade winds speeds should range between 10 to 20 mph. With relatively stable atmospheric conditions, few showers were anticipated.
COASTAL FLOODS -- The National Weather Service issues various public statements for hurricanes and other tropical weather systems as well as for other types of situations that can cause coastal floods. These statements follow the advisory, watch and warning format previously described, and they are intended to inform the coastal residents and commercial and recreational marine interests of a potentially hazardous weather situation. A full description of these statements appears in the Tuesday 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.