DATASTREME DAILY SUMMARY

Thursday, 14 December 2000


00Z Weather Systems


A WINTRY MESS MOVES TOWARD THE NORTHEAST -- A storm system that developed over the western Gulf of Mexico on Tuesday night featured heavy snow across the Ozarks, major icing across the southern Plains and severe thunderstorms close to the Gulf Coast on Wednesday. By late Wednesday night, the complex storm system included one low pressure center that was located over western Kentucky and another low center situated over southern Alabama. A trough line connected the two low pressure centers. The southern low was located along a frontal system that included a warm front that extended southeastward across the Florida Panhandle and the Gulf Coast to another low off the South Carolina coast. A cold front extended southward from the low in Alabama across the Gulf of Mexico. A widespread precipitation shield accompanying this storm system was found to the north of the lows, stretching from New York State and Pennsylvania in the Middle Atlantic States westward to southern Lake Michigan and southward to the central Gulf Coast. Snow continued to fall in the cold air across the Great Lakes, while rain fell from eastern Kentucky southward where temperatures were above the freezing point. In between, a large area of freezing rain fell across the upper Ohio Valley into the Middle Atlantic States, in an area with a relatively shallow subfreezing layer of air that remained near the earth's surface.

On Wednesday, a band of heavy snow fell from Oklahoma to central Indiana, with southwestern Missouri receiving the heaviest amounts. As of late afternoon record snow totals had fallen at Springfield (14.3 inches), St. Louis (5.8 inches) and Columbia (4.5 inches). The Springfield record was also a record for the month. Tulsa, OK received 4.8 inches of snow, which not only set a daily record, but also marked the fourth highest daily snowfall total for December in city history.

During the morning hours, the region receiving the major ice accumulations as a result of freezing rain stretched from Texas northeastward across Arkansas and into Tennessee. Much of the record 2.20 inches of precipitation that Shreveport received fell as freezing rain. By evening, freezing rain was falling across the Ohio Valley, the central Appalachians into the Middle Atlantic States. For several hours on Wednesday night, a freezing rain advisory was in effect for Kentucky, while an ice storm warning was issued for south central Ohio. Some freezing rain also fell across northern Georgia and the uplands of South Carolina.

Thunderstorms developed along and ahead of the cold front that extended southward from the low pressure center in Alabama. Some of the thunderstorms turned severe as winds that gusted to an estimated 65 mph produced damage across southern Mississippi on Tuesday afternoon.

By Thursday morning the low pressure system off the South Carolina coast is expected to move northward and develop multiple centers along the Middle Atlantic coast. The precipitation shield is expected to spread to the northeast. As a result, snow and winter storm advisories covered essentially all of New England and Upstate New York.

A record low temperature was reported on Wednesday morning from Massena, NY (21 degrees below zero).

ANOTHER ROUND ON THE WEST COAST -- A storm moved onshore along the Oregon coast on Wednesday evening. Precipitation associated with this system included a mixture of snow, ice pellets (sleet) and freezing rain that fell at Portland, OR and the Columbia Gorge. Snow fell across the Oregon Cascades southward into the northern Sierras, as well as the mountains of eastern Oregon and Washington State. Along the coast, rain spread as far south as San Francisco.

The area of precipitation is expected to spread inland on Thursday morning. A winter storm watch was posted for portions of interior Oregon, Washington State and Idaho, while snow advisories were in effect for the mountains of northern and central California, northern Nevada and Utah. By Thursday evening, the next storm system is expected to reach the Washington coast, accompanied by coastal rain and mountain snow.

UPPER AIR -- The mid and upper tropospheric charts for 00Z Thursday show a trough across the nation's midsection.

YESTERDAY'S TEMPERATURE EXTREMES ACROSS THE LOWER 48 -- The lowest temperature on Wednesday was 24 degrees below zero at Flag Island, MN. Wednesday's high was 86 degrees at Ft. Myers, FL.

ALASKAN WEATHER -- High pressure located over the Yukon Territory along with several large storm systems over the Bering Sea and the Alaska Peninsula produced strong winds across much of Alaska on Wednesday. Unalakleet and Golovin reported gusts to 47 mph and Red Dog Mine had gusts to 46 mph. One large low pressure system was situated over the central Bering Sea, with a frontal system that extended across western Alaska in the vicinity of the Yukon-Kuskokwim Delta. A secondary low pressure system was located near Cold Bay and the western Alaska Peninsula. Relatively cloud-free skies were found across interior and northeast Alaska in association with the Yukon high pressure center, while clouds covered most of southwest Alaska near the storm systems.

The lowest overnight temperature in Alaska as of Wednesday was 29 degrees below zero at Eagle. The highest temperature as of midafternoon was 48 degrees at Port Alsworth.

HAWAIIAN WEATHER -- A large subtropical high pressure cell located to the northeast of Hawaii produced trade weather across the islands on Wednesday. Clouds and showers were found along the windward sides of the islands. Relatively strong northeast trade winds were found on Wednesday. As the high drifts away from the islands, the trade winds should weaken and turn more toward the southeast. Small craft advisories were continued for all state waters.


HISTORICAL WEATHER EVENTS - 14 December

From the files of the Aviation Weather Center, Kansas City, MO and Intellicast


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URL Address: datastreme/learn/r_sum.html
Prepared by Edward J. Hopkins, Ph.D., email hopkins@meteor.wisc.edu
© Copyright, 2000, The American Meteorological Society.