THE WARM WEATHER CONTINUES -- The eastern two-thirds of the nation experienced a relatively warm early December day. Only the West Coast and the Great Basin, along with portions of Texas and coastal sections of the Southeast had highs that were either at or below the long-term average highs for the date. The largest departures in the observed high temperatures from the long-term average were found across the central Plains where highs were between 20 to 25 degrees above average. Record high temperatures were either tied or set on Monday in Kansas at Dodge City (71 degrees), Russell (70 degrees), Salina (69 degrees) and Wichita (67 degrees).
A large and persistent high pressure cell along the Eastern Seaboard continues to dominate the weather across the East, helping maintain the relatively warm conditions from the Atlantic westward to the nation's midsection. Sinking motion in the high not only produces relatively clear skies that allow for solar heating, but also acts to raise the air temperature as the result of compressional heating. Farther west, the southerly and southwesterly winds bring warm air northward. A warm front extending eastward across the Plains from a weak low pressure center over the Oklahoma Panhandle marked the leading edge of the warm air that was moving northward. Clouds and some widely scattered light rain were found to the north of this warm front.
ANOTHER STORM HITS THE PACIFIC NORTHWEST -- The next system in a series of storms to reach the West Coast was approaching the Washington coast on Monday evening. The storm consisted of an occluded low pressure center that was situated over the Alaska Panhandle and an occluded front that stretched southward along the coast of mainland British Columbia and Vancouver Island. The occluded front continued southward offshore of Washington State before becoming a cold front that curved westward. Widespread precipitation associated with the approaching front had spread across western Washington and northwest Oregon. Most of the precipitation along the coast and at lower elevations was falling as rain.
The previous storm system that had moved on to the West Coast had brought heavy snows to the mountains of the interior. Up to 20 inches of snow fell across the mountains of Idaho in the 24 hours ending on Monday morning. Farther south, snowfall totals of at least 10 inches were reported across northern Nevada. The remnants of this previous storm could be found on the Monday evening weather maps as a stationary front that stretched southwestward from the western Dakotas across the northern Rockies into the Great Basin. Widely scattered snow continued across the mountains of Idaho, Montana, Wyoming, Utah and northern Nevada on Monday night. A winter storm warning was posted for southern Nevada, where up to 5 inches of snow could fall at elevations above 5000 feet by morning. A snow advisory was posted for the Uinta and Wasatch Mountains near Salt Lake City, with up to 6 inches possible by morning. Farther south, the precipitation was widely scattered rain across southern Nevada and California.
The new storm that was approaching the Washington coast is expected to move inland on Tuesday. As much as 1.4 inches of liquid-equivalent precipitation is forecast to fall during the 24 hours ending on Tuesday evening along the Washington and northern Oregon coasts, as well as the western slopes of the Cascades. Winter storm warnings and snow advisories were in effect for the Olympics and the Cascades in Washington and Oregon. Snow levels are expected to drop to as low as 1500 feet and as much as 2 feet of snow are anticipated at some higher elevations in the Oregon Cascades by Wednesday morning.
Strong winds were also accompanying this new storm system. Gale warnings were in effect for the Oregon and Washington coasts from Florence, OR northward, including the Strait of Juan de Fuca and northern portion of Puget Sound. Heavy surf advisories were posted for the California coast from Point Arena south to the Mexican border.
UPPER AIR -- Both the 500 and 300 mb charts for 00Z Tuesday depict a pattern in the height field where the constant pressure surfaces ridge upward in the warm air across the eastern half of the country, but form a height trough in the cold layer extending upward through the troposphere in the West. This height trough is also associated with the storm system that moved across the Rockies and the Intermountain West.
TEMPERATURE EXTREMES IN THE LOWER 48 -- The lowest temperature on Monday was 8 degrees at Hibbing, MN, while Monday's highest temperature was 83 degrees at Fort Myers, Tamiami and Tampa, FL.
ALASKAN WEATHER -- Arctic air remains across most of mainland Alaska on Monday, the result of a ridge of high pressure that extended southeastward from the Arctic Ocean and the Chukchi Sea. Midday temperatures were below zero at most locations across the interior. While clouds were found over northwest Alaska, skies ranged from partly cloudy to mostly cloudy across interior Alaska. Weak onshore northerly winds helped produce snow at Barrow and Deadhorse. Freezing fog was reported at Fairbanks Airport, where visibility was reduced to 0.5 miles. One low pressure center was located over the Panhandle near Sitka. Snow fell across the Panhandle, with 9 inches of new snow reported by midafternoon just north of Juneau. With blizzard-like conditions expected in southeast Alaska, a winter storm warning has been posted for the area near Ketchikan. Another slightly weaker low pressure system was located along the southeast coast near Cordova. A cold front extended westward from this second low pressure center across the northern Gulf of Alaska and the Alaska Peninsula before becoming stationary over the central Bering Sea. Snow was reported at Glennallen. A major storm system in the western North Pacific was responsible for the high winds across the western Aleutians, where a high wind warning was in effect west of Adak.
The state's lowest temperature on Monday morning was 41 degrees below zero at Northway. The highest temperature across Alaska as of midafternoon on Monday was 43 degrees at Dutch Harbor.
HAWAIIAN WEATHER -- A strong 1036 mb high pressure system located to the northeast of the Hawaiian Islands maintained relatively strong trade winds across the islands on Monday. Several bands of clouds and heavy showers were detected around Hilo and along the windward coast of the Big Island. Some trade showers should be found on the windward slopes of the islands, and usually at night during the early morning. The high should move toward the southeast and weaken by midweek, resulting in a slight weakening of the trade winds to more typical values of between 15 to 25 mph by Thursday. Small craft advisories remained in effect for coastal waters along with high surf advisories for the east shores of the islands.
EYE ON THE TROPICS -- Tropical Storm Olga weakened as it moved northward across the western Atlantic Ocean, resulting in the system being downgraded to tropical depression status. As of late Monday night Tropical Depression Olga had maximum sustained surface winds of 35 mph. Its position was approximately 360 miles southwest of Bermuda and movement was to the east at 7 mph.
CLOSING THE BOOKS ON NOVEMBER -- The National Climate Data Center in Asheville, NC has posted a listing of some of the notable extremes in temperature, precipitation and other weather elements across the nation for the month of November.
A coastal flood occurs when low lying land areas bordering a large body of water are inundated. Coastal flooding may be caused by abnormal rise in water level associated with an approaching ocean storm or by large breaking waves on the shore from large ocean swells. The extent of coastal flooding depends upon the tide levels, the underwater and shoreline topography and the runoff from rivers and estuaries.
Coastal floods are often associated with high water from a storm surge, caused by winds generated by tropical (hurricanes) or extratropical cyclones. Coastal flooding can be produced also by a tsunami, a seismic sea wave produced by earthquakes, landslides or volcanic activity; these waves are erroneously called tidal waves. Alaska, Hawaii and the Pacific coast are most vulnerable to a tsunami.
The greatest danger and damage associated with most tropical cyclones (hurricanes) is the storm surge. A storm surge is a dome of water, perhaps 50 miles wide, that sweeps across the coastline ahead of a tropical cyclone landfall. The magnitude of a storm surge depends upon the strength of the storm, the ocean bottom conditions where the surge comes onshore, the storm's movement relative to the shoreline, and the tides at landfall time.
In addition, the destruction of the storm surge is often compounded by the hammering effect of the breaking waves. Because many tropical cyclones produce excessive rainfall rates and total amounts of precipitation even after landfall, they may be also responsible for floods and flash floods. The strong and gusty winds, coupled with the possibility of tornadoes, are added perils to residents of areas near the landfall of a hurricane.
Coastal floods and beach erosion can also be associated with extratropical cyclones, such as the "nor'easters", that may batter the East Coast from Cape Hatteras to Maine, especially during the winter season. Coastal flood watches and warnings are issued by certain designated National Weather Service Offices and pertain to the region extending from the ocean beaches inland, including waterways, estuaries and river mouths.
The National Weather Service issues various public statements for 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.
To be submitted on the lines for Tuesday on the Study Guide, Part B, Applications', Week 12 Chapter Progress Response Form, under section B. Daily Summary.
From the files of the Aviation Weather Center, Kansas City, MO and Intellicast