The following highlights of the national weather have been extracted from the surface weather map for Tuesday night:
COASTAL STORM BRINGS WINTRY MIX TO THE NORTHEAST -- Widespread precipitation was moving northward across the northeastern quadrant of the nation on Tuesday evening. Rain was falling along coastal sections of the Middle Atlantic States and the Northeast, extending northward from Tidewater Virginia northward to Downeast Maine. By late evening most of the heavy rain was found in New England, while light rain and drizzle continued across the Middle Atlantic States. Inland, snow was falling across the higher terrain from the Poconos of northeastern Pennsylvania northward across the Catskills and Adirondacks of Upstate New York, along with Vermont's Green Mountains, New Hampshire's White Mountains and the higher terrain of northern Maine. Ice pellets (sleet) and mixed precipitation (rain and snow) were also found across sections of the Northeast, primarily in the transition zone between the main areas of coastal rain and higher elevation snow.
The precipitation moving to the north across a wide area of the Northeast was due to a coastal storm that had been traveling northward off the Middle Atlantic coast on Tuesday. During the early morning the storm was passing the Outer Banks of North Carolina. By early evening, the center of this storm was moving onto the southern New England coast near Rhode Island's Narragansett Bay. As the storm moved northward it deepened or intensified, with a drop in central pressure and a corresponding increase in the winds.
The counterclockwise circulation of winds around the storm's low pressure system were carrying abundant water vapor onshore on easterly and northeasterly winds on the northern side of the low pressure center. Therefore, the precipitation was substantial in some areas of New England and New York State. According to 24-hour radar estimates, all but northern New England received nearly one inch of precipitation. Sufficiently warm air was being carried onshore that coastal areas were receiving primarily rain. Some areas in southern New York State and western Connecticut to the north of the New York City metropolitan area and in the area around Boston, MA received over two inches of rain. Orographic lifting along the higher terrain inland also helped enhance precipitation totals. Furthermore, the air in the interior sections was sufficiently cold to support snowfall. By late evening, two to three inches of snow fell across sections of northern Maine, while nearly eleven inches of snow were reported in New Hampshire and 14 inches in Vermont.
The storm was forecast to continue traveling in a somewhat erratic path toward the north on Wednesday, first moving across Massachusetts Bay and the Gulf of Maine during the morning and then tracking across Maine during the early evening. This storm may intensify slightly before it begins to occlude as it moves into Maine.
Widespread precipitation should continue around the northern and western sides of the storm's low pressure center. As much as four inches of liquid-equivalent precipitation was forecast to fall across eastern Maine during the 24 hours ending on Wednesday evening. Other areas across northern New Hampshire, Vermont and New York State could receive over two inches of precipitation during this time span. Rain should continue along the coast and across eastern Maine due to the maritime influence on the onshore flow of humid air. A flood watch was issued for coastal sections of Maine that would continue into Wednesday afternoon due to the heavy rain.
Farther to the west, snow, ice pellets and freezing rain would continue through the morning. As of late Tuesday evening, winter storm warnings and winter weather advisories were continued across northeastern Pennsylvania, most of western and northern New York State, along with most of Vermont, New Hampshire and Maine. Some of these warnings and advisories would continue into early Wednesday afternoon, while those in western New York could run through early Thursday morning. In northern Maine, four to eight inches of snow could fall, along with one to inches of ice pellets and one half of an inch of ice. Anticipated snowfall totals across the Catskills and Adirondacks in New York State could be as high as 14 inches.
The storm was expected to continue generating strong winds across New England. These winds would be relatively strong over coastal waters. A storm warning was in effect along the Maine coast through early Wednesday morning where northeast winds could gust to over 60 mph. A coastal flood advisory was posted as the onshore winds would pile water against the beaches and cause splash-over with minor coastal flooding and beach erosion.
PARADE OF STORMS CONTINUE TO HAMMER THE WEST COAST -- Rain was falling across western Washington on Tuesday evening. The precipitation was associated with a cold front that had moved onto the coast of Washington and Oregon during the midday hours of Tuesday. This cold front trailed from a storm that moved to the northeast to reach the coast of British Columbia to the north of Vancouver Island during afternoon. This storm was another in the series of storms moving across the eastern North Pacific toward the western coast of North America, carried along by strong jet stream winds in the mid and upper troposphere. Farther to the southwest, another storm was developing as a wave developed along sections of the cold front near the Hawaiian Islands. By late afternoon the low pressure center for this next storm was located approximately 800 miles to the west of the Oregon coast. Movement of this new storm was also to the northeast toward the British Columbia coast. However, the cold front trailing from this new storm was expected to reach the Washington coast by Wednesday evening and move inland. By early Thursday another low pressure center should develop along a section of the front that was to be located off the Oregon coast. The low pressure system and accompanying cold front would move across the Cascades into interior sections of the Northwest by Thursday evening. Farther south, the cold front would move toward the east and south, passing across the northern Sierras of California and into the Great Basin of Nevada.
A deep flow of humid air that could be described as an "atmospheric river" was carrying humid air from the subtropical Pacific near the Hawaiian Islands toward the Pacific Northwest coast. This onshore flow coupled with orographic lifting provided by the Olympics, the Cascades and the Oregon Coast Ranges should result in considerable precipitation totals. Initially, most of the rain would be in western Washington, but over time, the focus would shift southward as the fronts progressively move toward the south. Over two inches of rain were expected to fall along the coast from northern California to Washington during the 24 hours ending late Wednesday afternoon. Some locations along the Olympic Mountains on Washington's Olympic Peninsula could receive over four and a half inches of rain. Flood and flash flood watches were in effect through Friday afternoon across the Olympic Peninsula and the western slopes of the Cascades in the Cascades. Additional flash flood watches were posted for southwestern Oregon and across northern California.
The series of storms approaching the West Coast would also produce strong winds, initially along the coastal areas and the Cascades in Washington and Oregon. Later, the strong winds accompanying the cold front would spread into California and then into the Great Basin of Nevada. High wind warnings were in effect through late afternoon across western Washington and northwestern Oregon. South to southeast winds could gust to 70 mph. Storm warnings and gale warnings were also posted for the coastal waters of Washington that included the state's inland waters north of Seattle.
The storm that would move into northern California beginning late Wednesday and continue through Thursday could be one of the strongest to hit the region in several years. Strong winds and heavy snowfall could produce blizzard conditions across the northern Sierras, where a blizzard warning was posted for elevations above 6000 feet that would run from Wednesday night through early Friday afternoon. Some locations near Lassen Volcanic National Park and Donner Pass could receive up to three feet of snow. The snow along with the blowing snow produced winds that could gust to 80 mph would cause whiteout conditions.
UNSETTLED WEATHER ACROSS WEST TEXAS -- A few showers and thunderstorms were detected to be continuing into late Tuesday evening across west Texas and adjoining sections of southeastern New Mexico and the northern Mexican State of Chihuahua. These showers and thunderstorms produced little more than one half of an inch of rain according to radar estimates. This precipitation was due to a disturbance in the mid-tropospheric wind flow across southern Arizona and New Mexico.
Showers and thunderstorms could develop across the Big Bend area of west Texas on Wednesday afternoon. Daytime surface heating could enhance convection. Sufficiently humid air from off the western Gulf of Mexico would move toward the northwest into the region to supply the showers and thunderstorms with water vapor. Rainfall totals during the 24 hours ending early Wednesday evening should amount to approximately one quarter of an inch along the Rio Grande Valley.
QUIET WEATHER CONTINUES ACROSS NATION'S MIDSECTION -- Relatively quiet weather was found elsewhere across the nation on Tuesday evening. A large ridge of high pressure was centered over Ontario and extended southward across the western Great Lakes and the Mississippi Valley was responsible for the tranquil weather. This high pressure ridge could be called a "dirty high" because clouds were moving across sections of the Midwest, passing across the region dominated by high pressure. These remnant clouds were moving through a region that was atmospherically stable due to the presence of a subsidence inversion caused by the presence of high pressure.
The high pressure cell was forecast to drift eastward across the Great Lakes on Wednesday.
YESTERDAY'S TEMPERATURE EXTREMES ACROSS THE CONTINENTAL US -- Tuesday's lowest temperature was 5 degrees below zero at Willow City, ND while the highest temperature on Tuesday was 85 degrees at Riverside, CA.
ALASKAN WEATHER -- Variably cloudy sky conditions prevailed across mainland Alaska on Tuesday afternoon, as skies ranged from partly cloudy to cloudy or overcast. Satellite imagery animations showed several bands of clouds continuing to circulate around a nearly stationary storm that was centered over the northwestern Gulf of Alaska off Kodiak Island. A stationary front stretched across southern Alaska, from the Alaska Peninsula eastward to the Alcan border and then into the southern Yukon Territory. A low pressure trough and front stretched across the southeastern Panhandle and into adjacent sections of northwestern British Columbia. Rain continued to fall along coastal sections of southern Alaska, extending from western sections of the Alaska Peninsula eastward to southern sections of the Panhandle. Some coastal areas across south central Alaska also reported a mixture of rain and snow. Snow was also detected across interior sections of the 49th State, especially along the Yukon Valley.
A tight pressure gradient remained across Alaska on Tuesday, situated between high pressure over the Arctic Ocean to the north and the large storm over the northwestern Gulf of Alaska to the south of the state. This tight pressure gradient was responsible for winds gusting to 65 mph along the Chukchi Sea coast. In interior Alaska, one station in the northeastern Brooks Range had a gust to 89 mph before the wind sensor stopped reporting. Southern Alaska had winds gusting to 50 mph at some locations.
Freezing rain was expected across southwestern Alaska near the storm's center in the transition zone between rain and snow. A freezing rain advisory was in effect for sections of the Alaska Peninsula and the area around Bristol Bay through midday on Wednesday. Farther north, the strong winds and the relatively cold air have caused wind chill temperatures to drop to dangerous levels. A wind chill warning was to remain in effect through early Wednesday evening for the northwestern Brooks Range as wind chill temperatures could fall to 70 degrees below zero at times.
The state's lowest overnight temperature on Tuesday morning was 24 degrees below zero at Nuiqsut. The highest temperature by midafternoon of Tuesday was 55 degrees at Metlakatla.
HAWAIIAN WEATHER -- With a ridge of high pressure stalled across the Hawaiian Islands on Tuesday afternoon, skies were clear to partly cloudy at most reporting stations. Surface winds across the islands were also light in intensity and variable in direction. The east-west oriented axis of the ridge was located over Maui. This ridge was located over the islands, pushed southward as a midlatitude cold front was approaching the islands from the northwest. A dry and stable air mass was found across the Aloha State, as indicated by soundings from the afternoon radiosonde ascents at Hilo and Lihue. Precipitable water levels were below normal and a relatively strong trade wind temperature inversion was detected at altitudes below 4000 feet. The light regional winds permitted development of afternoon sea breezes. Satellite image animations revealed few clouds moving across the waters around the islands. However, clouds remained across the volcanic peaks on the Big Island and Maui. Farther to the north, a line of low clouds was moving toward the southeast along the cold frontal boundary. No significant shower activity was detected by radar.
Following an anticipated clear and cool night due to land breezes, the weak cold front was forecast to move to the southeast along the island chain on Wednesday and Thursday. Showers accompanying the front should affect the northern and windward sides of the islands. Northeast trade winds following behind the cold front should increase in strength on Thursday and then decrease on Friday as another front approaches the island.
The instrumented buoy moored to the northwest of Kauai was detecting large ocean swell approaching the Hawaiian Islands from the northwest on Tuesday. The swell was expected to increase, which would result in surf reaching warning-level heights along the north- and west-facing coasts of the islands. Therefore, a high surf warning was to continue through early Thursday for the north- and west-facing coasts of Niihau, Kauai, Oahu and Molokai and for the north- facing coast of Maui. The ocean swell, together with anticipated increased trade winds following frontal passage, a small craft advisory was to run through early Thursday morning for most state waters.
PUERTO RICO AND US VIRGIN ISLANDS WEATHER -- Clear to partly cloudy skies were reported across Puerto Rico, Vieques, Culebra and the Virgin Islands through late Tuesday night. Satellite imagery revealed only a few scattered high clouds traveling from west to east across the region. No measurable precipitation was reported across the islands on Tuesday. Regional surface winds remained light and from an easterly direction. A weak pressure gradient across the islands between high pressure well to the northeast and low pressure near South America was responsible for the light regional winds. The light winds permitted afternoon sea breezes to develop, along with a few convective clouds over the islands. After sunset, the sea breezes gave way to land breezes and clearing over the islands. The air mass was dry and stable, which meant few clouds or showers.
The temperature at the airport for Charlotte Amalie on the island of St. Thomas, USVI fell to 69 degrees on Tuesday morning, which set a new low temperature record for the date.
Generally fair weather should continue across the islands on Wednesday due to the dry and relatively stable air mass located across the region. Light easterly to east-southeasterly trade winds were forecast to continue, which would result in the development of afternoon sea breezes and nighttime land breezes..
Ocean swells from the north were expected to approach the local waters surrounding the islands and peak early on Wednesday. The swells would increase the high surf along the north-facing beaches of some of the islands. Therefore, a high surf advisory was in effect through at least Thursday for the north-facing coasts of Puerto Rico, Culebra, Vieques and the northern Virgin Islands. In addition, winds from the east-southeast were expected to strengthen. The combination of the winds and the ocean swell necessitated the posting of small craft advisories for the Atlantic waters and the Mona Passage.
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, 2014, The American Meteorological Society.