DataStreme Spring 2002 will return with new learning files on Preview Week, 21 January 2002. Meteorological products will continue to be available throughout the break period.
WEATHER OVER THE WEEKEND -- A nearly stationary frontal zone stretched across the Southeast and the southern Plains during the first half of the weekend. This front separated a relatively warm and humid air mass located over Florida and Georgia from slightly cooler air across the Ohio Valley and Midwest. A band of rain and some embedded thunderstorms stretched along this front. A weak low pressure area developed along the front on Friday and by Saturday morning the low had intensified. During Saturday the low began to move toward the northeast. By Saturday night the low pressure center was located in southwestern Virginia. A large precipitation shield developed to the north of the surface low and spread across the Middle Atlantic States. With cold air associated with high pressure over the St. Lawrence Valley, some of the rain changed over to snow, resulting in the first measurable snowfall of the season in many locations. Up to eight inches of snow fell over the higher terrain, from the Poconos in northeast Pennsylvania across the Catskills of southern New York into the Berkshires of western Massachusetts. Albany, NY had a record 4.3 inches of snow on Saturday.
As the low pressure system developed along the stationary front, a cold front began to move southward across the southern Plains. On Saturday the cold front had reached the Gulf Coast. A large band of precipitation developed along this cold front. Record rainfall fell across Austin, TX on Saturday, with 1.06 inches at Bergstrom Airport and 1.38 inches at Camp Mabry.
Out West, high pressure built into the Great Basin early Friday. This high, which was of Pacific origin, drifted eastward across the central Rockies on Saturday. By Sunday morning the high had spread into the western Plains.
As the high moved onshore on Friday, westerly winds on the north side of the high brought precipitation across the Pacific Northwest. Between 6 to 24 inches of snow fell within the 24 hours ending on Friday morning across the mountains of Idaho. High winds were reported on Saturday morning across Montana, with winds gusting to 85 mph near Helena and to 70 mph near Glacier National Park.
On the south side of the high pressure cell an easterly flow subjected southern California to strong Santa Ana winds. Early Saturday morning, winds gusted to 100 mph at Fremont Canyon in the Santa Ana Mountains. Many other locations had gusts to over 50 mph. At least three injuries were sustained at several construction sites in San Bernardino County on Friday due to the high winds. Additional damage to buildings and power lines was reported on both Friday and Saturday. The Santa Ana winds also produced record high temperatures as the result of downslope compressional heating of the air. In addition these east winds also prevented an onshore flow from off the cooler Pacific Ocean. Record high temperatures were set on Friday at La Mesa (84 degrees) and Newport Beach (82 degrees) and Oceanside Harbor (81 degrees). On Saturday, Oceanside Harbor registered a record high of 82 degrees.
On Saturday morning a cold front trailing from a trough of low pressure over northern British Columbia was approaching the Pacific Northwest from off the Pacific Ocean. Some pre-frontal precipitation fell across western Washington. By evening the front had moved across the Cascades, with some precipitation behind the front. A low pressure center developed along the cold front over central California. By Sunday morning this distinct low pressure system had moved to the east-southeast across the Sierras into Nevada.
Much of nation east of the Rockies remained relatively warm on Friday, with high temperatures ranging from 10 to 15 degrees above the long-term average highs for the date. On Friday afternoon Tallahassee, FL (81 degrees) and Atlanta, GA (74 degrees) reported record-tying high temperatures. Only a portion of the northern Plains and much of the Rockies and Intermountain West had highs that were near or slightly below average. On Saturday, the Southeast and the northern Plains experienced above average temperatures, with highs approaching 20 degrees above the average highs for early December. Macon, GA and Cape Hatteras, NC tied record high temperatures of 79 and 74 degrees, respectively on Saturday. Southern New Mexico and the Rio Grande Valley in Texas had highs that were on the order of 10 degrees below average. By Sunday afternoon, the central and northern Plains had high temperatures that ranged between 20 to 25 degrees above average. The Southeast also had highs that were above average. The southern Plains and the Texas Gulf Coast were relatively cool, with highs that were between 15 to 20 degrees below the long-term average highs for the date.
WEATHER FOR THE START OF THE NEW WEEK -- The following highlights of the national weather have been extracted from the surface weather map for late Sunday night.
High pressure located across the Middle Atlantic States produced relatively tranquil weather, with relatively cloud-free skies across much of the Eastern Seaboard. Some foggy conditions were beginning to develop across New England as overnight temperatures dropped to the dewpoint. Southwesterly winds on the western flank of this high pressure system brought a return of warmer air to the Midwest. The high is expected to drift eastward on Monday.
Some rain was falling along the Gulf Coast and the Florida Peninsula in association with the stationary front that stretched across central Florida and the Gulf of Mexico. This front trailed from a storm system that was located over the North Atlantic to the east of the Canadian Maritimes. A low pressure center is forecast to develop along this front early Monday and move along the front toward the northeast, reaching the South Carolina coast by Monday evening. A large precipitation shield should spread across the Southeast to the north of the developing low pressure center. As much as 1.7 inches of rain could fall across portions of the mountainous areas of the western Carolinas and northeast Georgia during the 24 hours ending on Monday evening.
A low pressure system located along the lower Colorado River in southeastern California and southern Nevada was spreading some light rain and gusty west to northwest winds across southern California, especially in the vicinity of Los Angeles. With wind gusts to just below 40 mph, wind advisories were posted for the mountains around the Los Angeles Basin. The low pressure system is expected to move eastward on Monday, reaching the Four Corners by evening. An area of precipitation in the form of low elevation rain and mountain snows is expected to accompany the eastward movement of the storm. As a result, a winter storm watch was posted for Monday night and Tuesday to include the San Juan and Sangre de Cristo Mountains in southern Colorado, as well as the mountains of northern and western New Mexico. Since the track of the storm was still uncertain, a forecast of the amount of anticipated snow was not made. However, windy conditions were expected.
Rain was beginning to spread across the Olympic Peninsula ahead of a warm front that was moving toward the Washington state coast. This warm front was associated with a storm system located in the eastern Gulf of Alaska. The storm system is expected to make landfall by early Monday. Gale warnings were posted for the Washington State coast from Cape Flattery to Cape Shoalwater. Snow advisories were in effect for the Olympics and the Washington Cascades through Monday morning for a possible accumulation of nearly a foot of new snow at elevations above 2000 feet. Farther east, snow advisories were also posted through Monday afternoon for the mountains in eastern Washington and northern Idaho, where up to 6 inches of new snow could fall.
Heavy surf advisories were in effect along the California coast from Point Arena to Point Piedras Blancas.
UPPER AIR -- The 500 and 300 mb charts for 00Z Monday indicate a cold pool of air over the Southwest, resulting in an elongated height trough over Nevada and southern California. Another trough and associated pool of cold air in the mid to upper troposphere was also detected over the southern Plains. A height ridge was found over the eastern Great Lakes.
TEMPERATURE EXTREMES ACROSS THE LOWER 48 -- On Sunday, the lowest temperature reported in the continental U.S. was 15 degrees below zero at Gunnison, CO, while Sunday's highest temperature was 84 degrees at Brooksville, Marathon, Pembroke Pines and Punta Gorda, FL.
ALASKAN WEATHER -- A ridge of high pressure extending across northwest Alaska and the North Slope continued to bring cold air to northern Alaska. Most locations across the interior experienced subzero midafternoon temperatures, with the lowest reported at Fort Yukon with 35 degrees below zero. Northeasterly winds off the Arctic Ocean brought cloudy skies to the North Slope, along with snow at Deadhorse and Wainwright. Skies ranged from scattered to broken across interior Alaska, with snow reported Kaltag and McGrath. An elongated storm system was situated over the east Gulf of Alaska, with the primary low pressure center located just to the southwest of Yakutat and an occluded front that extended southward along the coast of the Panhandle to a secondary low pressure center in the vicinity of the Queen Charlotte Islands. Clouds and areas of rain and snow were reported across southeast Alaska. Port Alexander had 1.02 inches of rain in the 24 hours ending on Sunday afternoon. An east-west oriented stationary front extended from the Alcan border in Southeast Alaska westward along the Gulf coast to a low pressure center over southwest Alaska in the vicinity of King Salmon and then out across the Alaska Peninsula and southern Bering Sea to an elongated low pressure center just to the north of the central Aleutians. Cloudy skies were found across southwest Alaska, with snow at Dillingham and Iliamna.
The lowest overnight temperature in Alaska as of Sunday was 40 degrees below zero at Northway and the midafternoon highest statewide temperature was 43 degrees at Atka, Port Alexander, Cold Bay, Hydaburg, Dutch Harbor and Sand Point.
HAWAIIAN WEATHER -- A large 1039 mb high pressure cell located to the west of California and to the northeast of the islands was responsible for strong and gusty northeast trade winds across the Aloha State. With the low expected to drift slowly eastward, the trade winds should remain in the 15 to 30 mph range until midweek. Scattered showers to the northeast of the islands should move across the islands during the next several days. The high surf generated by the strong trade winds has necessitated a high surf advisory for the east shores of the islands. Small craft advisories were in effect for state waters .
AN UPDATE -- Bill Gray of Colorado State University released his first forecast for the 2002 North Atlantic hurricane season on Friday. He predicts 13 named tropical cyclones (both tropical storms and hurricanes), eight of which should be hurricanes. He also anticipates that four of the hurricanes could be intense, reaching at least Category 3 status on the Saffir-Simpson Hurricane Intensity scale. Long-term averages for the basin include 9 named storms, 6 hurricanes and 2 intense hurricanes. He also anticipates an above average probability that a major hurricane would make landfall along the U.S. coastline.
From the files of the Aviation Weather Center, Kansas City, MO and Intellicast