THE MID-ATLANTIC IS SPARED A MAJOR SNOW -- A storm that moved out of the Midwest into the Middle Atlantic states on Monday morning had the potential for significant snow, but moved quickly out to sea leaving little wintry weather over the region, except for the higher elevations of northern Pennsylvania. Morning snows tapered off quickly and skies began to clear across the Eastern Seaboard.
RECORD WARMTH IN THE NATION'S MIDSECTION -- The unseasonably warm weather continued across a large portion of the country for another day on Monday. Relatively high pressure over many areas of the country permitted relatively quiet weather conditions. As of late Monday night, one high pressure cell located over Tidewater Virginia dominated the weather over the Middle Atlantic and Southeastern States. Farther west, another high pressure cell was located over the central Rockies. High temperatures on Monday afternoon were above the long term average highs for the date for most of the country, with the exception of the extreme Northeast and of the West and Southwest. Numerous record high temperatures were either tied or set across the southern and central portions of the country on Monday. Among these, San Angelo, TX set a record with 86 degrees, while New Orleans, LA registered 92 degrees. Concordia, KS had an afternoon high that not only set a daily record high, but was the warmest day in February with 74 degrees. Other daily records were reported from locations in Nebraska, Missouri, Iowa, Arkansas, Florida, South Carolina and Tennessee.
WINTRY WEATHER DESCENDS UPON THE PACIFIC NORTHWEST -- The most recent storm system moved onshore on Monday and by late evening, the low pressure center was situated over interior British Columbia with a cold front that trailed southwestward over the Pacific Northwest. A broad area of precipitation, to include both rain and snow, accompanying this system was found from British Columbia south to northern California and eastward into Idaho. On Sunday, 1.21 inches of rain fell at Sacramento, (Downtown), a record for the date. Because of the rains, flood warnings were in effect for several rivers in Washington State, Oregon and northern California.
While snow initially fell across the higher elevations of the Cascades, Olympics and Sierras, cold air being brought into the system from the north and west could cause snow levels to drop. Snow showers were reported on Monday afternoon in communities near sea level that are located around Washington's Puget Sound. Forecasts indicate that snowfall could occur at elevations between 500 and 1000 feet near Seattle.
In addition to dropping snow levels, other indicators of the cold air include small hail and coastal thunderstorms. Both were observed on Monday in western Washington State. These two events typically are the result of sufficiently cold air aloft, which creates an atmospheric condition where vigorous vertical motion is not suppressed. Satellite imagery also showed a cloud pattern that indicated cold air pouring over relatively warmer surface water.
As this storm system continues to move eastward, heavy snow could fall across the mountains. More than a foot of new snow is anticipated over the northern Sierras and southern Cascades, where winter storm warnings were posted, effective for Monday night into Tuesday. Winter storm watches were posted for Tuesday and Tuesday night for the mountains of Montana, and Wyoming. Snow advisories for 4 to 8 inches of snow were in effect for the Wasatch Mountains of Utah.
TEMPERATURE EXTREMES IN THE LOWER 48 -- The lowest temperature in the lower 48 states on Monday was 11 degrees below zero at Berlin, NH and the highest temperature for Monday was 92 degrees at Laredo, TX.
ALASKAN WEATHER -- The ridge of high pressure associated with the massive arctic air mass remained anchored over western Alaska on Monday. This high pressure ridge stretching from Far Eastern Russia to the Yukon Valley was located between a trough of low pressure over the Beaufort Sea to the north and an intense storm system to the south that was situated over the Gulf of Alaska. Monday represented the fourteenth day of this current northern Alaska "cold spell". Morning temperatures across the central interior under this arctic air mass fell to near 60 degrees below zero, while temperatures near the coast reached 40 degrees below zero. Record low temperatures were established on Monday at Bettles, Galena and Tanana, where the temperature fell to 60 degrees below zero at all three stations. The minimum temperature reported at McGrath on Monday morning was a record setting 55 degrees below zero, representing the second record in two days and the third in one week. Cloud cover over Fairbanks and other locations in the eastern interior kept overnight low temperatures from falling to near record levels.
A storm system remained over northern Gulf of Alaska on Monday. This storm system was responsible for clouds and precipitation over southeast Alaska. Snow continued at Yakutat, adding to the 73 inches on the ground. Several buildings collapsed under the weight of the snow and off-road travel is impossible. Light snow was also detected over the Tanana Valley near Fairbanks. Strong winds with gusts to 50 mph remained across the south central coast as a tight pressure gradient continued around the north and west side of the low pressure system. Another storm system was moving across the western Aleutian Islands.
An assortment of wind-chill advisories and warnings remained in effect for several locations, as Cantwell in the Alaska Range reported a wind-chill equivalent temperature of 87 degrees below zero and along the Arctic Ocean both Prudhoe Bay and Deadhorse had wind-chill equivalent temperatures of 88 below.
Monday morning's overnight lowest temperature in the state was 62 degrees below zero at Bettles, Huslia and Tanana. The state's highest temperature as of mid-afternoon on Monday was 37 degrees at Adak and Shemya.
HAWAIIAN WEATHER -- The ridge of high pressure remained located 1500 miles to the north of the Hawaiian Islands, producing the gusty northeast trade winds and dry weather over the islands. However, this high pressure ridge is expected to weaken by midweek, causing a corresponding weakening of the trade winds. The chance of showers should increase by the end of the week. Small craft advisories continued for state waters and high surf advisories were in effect for the northwest shores of the islands.
DECIPHERING THE SURFACE WEATHER MAP -- Local observations are depicted on weather maps as numbers and symbols plotted in, on, and around circles drawn at each station location, forming a "station model". The station model on which Online Weather maps are based can by seen by clicking on the Online Weather Homepage "Online Weather Map Symbols" . More details are provided in Tuesday's optional electronic 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.