The following highlights of the national weather have been extracted from the surface weather map for Thursday night:
STORM WINDS DOWN ACROSS THE NORTHEAST -- Light precipitation was widely scattered across New England, coastal areas of the Middle Atlantic States and the eastern Great Lakes on Thursday evening. Snow flurries and light snow fell across sections of Maine, New Hampshire and Vermont in northern New England and across sections of southeastern New York State, New Jersey and eastern Pennsylvania in the Middle Atlantic States. A variety of precipitation including snow and freezing rain was reported in western New York State.
This precipitation was associated with the remnants of the coastal storm that brought heavy rain to coastal New England and heavy snow to the Appalachians on Tuesday and Wednesday. As of early Thursday evening the remnants of this storm consisted of a surface low pressure center that was located near Quebec City, Quebec along the St. Lawrence Valley. An occluded front extended to the east across eastern Quebec and New Brunswick to a point of occlusion over the North Atlantic south of Newfoundland. In addition to the surface low pressure center, a column of cold air extended upward through the troposphere over northern sections of New England and Upstate New York. The counterclockwise circulation of winds around this cold air column was circulating humid air along with clouds and light precipitation from the Atlantic across eastern Canada into the Northeastern States.
The surface low pressure center was forecast to travel eastward across eastern Canada on Friday. By evening the low pressure center should be located near New Brunswick's capital city of Fredericton. Scattered system snow and lake-enhanced snow should continue to fall across New England and Upstate New York. Several inches of additional snow could fall across the higher terrain. Freezing drizzle was also possible across western New York State. Winds associated with the system could cause some blowing snow.
QUIET WEATHER ACROSS NATION'S MIDSECTION -- Generally dry and uneventful weather prevailed across a wide area of the nation on Thursday evening, extending from the Midwest to the Rockies and from the western Great Lakes southward to the Gulf Coast States. An elongated ridge of high pressure with an axis extending along the Mississippi River was responsible for the quiet weather.
Although most of the nation's midsection was experiencing dry weather on Thursday evening, scattered light rain was detected across sections of east Texas and adjacent sections of northern Louisiana and southern Oklahoma and southern Arkansas. A weak disturbance had developed in the southerly flow of winds around the western limb of the high pressure ridge that was responsible for the rain. To the north of this disturbance, a stationary front extended across northern Oklahoma. The southerly flow of air from the western Gulf of Mexico was bringing water vapor into the southern Plains to support the scattered light rain.
Elsewhere, unseasonably mild air was found across most of the western half of the nation. Afternoon high temperatures across the Plains and the Rockies were 10 to 20 Fahrenheit degrees above the average highs for mid December. The warm air was due to a southerly flow of air that was located between the high pressure located over the Mississippi Valley and a large storm moving onto the West Coast.
The high pressure ridge was forecast to remain nearly stationary across the Mississippi Valley on Friday. As a result, the tranquil weather should continue across most of the nation's midsection. In addition, the area of rain that was located over the southern Plains was expected to remain stationary through most of Friday. This precipitation would be situated along the stationary front that would stretch across the region. As much as one half of an inch of rain could fall during the 24 hours ending early Friday evening over the Red River Valley in southern Oklahoma and north Texas.
STORMY WEATHER CONTINUES ALONG WEST COAST -- Moderate to heavy rain continued to fall along the central California coast and into the northern San Joaquin and southern Sacramento Valleys on Thursday evening. To the east, locally heavy snow was falling across the higher terrain of the Sierras. Farther to the north, rain was falling across western Washington. This region was also experiencing windy conditions.
The locally heavy rain and snow along with the winds were accompanying another in the series of storms that have traveled across the eastern North Pacific and came onshore along the western coast of North America. The system responsible for the precipitation and winds along the West Coast consisted of a relatively deep low pressure center that was located approximately 100 miles to the west of the mouth of the Columbia River that separates Washington and Oregon. The storm's central pressure was 974 mb during the late afternoon. The other part of the storm consisted of the cold front that trailed southward across western sections of Washington and Oregon and northern California. A weak low pressure had developed along the cold front over northern California that was helping enhance the precipitation across the region north of the San Francisco Bay area.
Over five inches of rain fell near Monterey and in Marin County to the north of San Francisco during the 24 hours ending late Thursday afternoon. At least two inches of rain fell across northern California, from Sacramento north to Redding. Flooding occurred in the San Francisco and Monterey Bay areas.
Several severe thunderstorm cells moved onto the northern California coast and into southwestern Oregon during the hours just before sunrise became severe as they generated strong damaging thunderstorm winds.
The strong non-thunderstorm winds were responsible for a fatality in the Portland (OR) metropolitan area when a tree fell upon an automobile late Thursday afternoon. In Washington, winds gusted to 70 mph near Port Townsend on the Admiralty Inlet on the Olympic Peninsula. Winds gusted to 64 mph in southern California near Santa Barbara. To the east, winds exceeded 100 mph along the eastern slopes of the Sierras near Yosemite National Park.
The storm would continue affecting the West Coast on Friday as it was forecast to move eastward. The storm's surface low pressure center was expected to travel to the northeast, crossing British Columbia's Vancouver Island before dawn on Friday. By evening the low pressure center should have crossed the Canadian Rockies and begun reorganizing in Alberta on the eastern slopes of the mountains. As the surface low pressure center would track into British Columbia, northern sections of the trailing cold front were expected to continue traveling eastward across the Cascades, reaching the northern Rockies in Idaho and western Montana by early Friday morning. Farther south, sections of the front would travel across the Sierras. By early Friday evening a large section of the front would be stretched across the Intermountain West from central Idaho southward to southeastern California. One of the low pressure centers that would form along the front was expected to develop as the front moves across the Great Basin on Saturday. Eventually, this low could become a significant weather system that would move across the central Plains after organizing over the eastern slopes of the Rockies by early Sunday.
The storm would continue to bring abundant quantities of precipitation onto the West Coast due to a feed of humid air that originated over the subtropical North Pacific. Some isolated thunderstorms could develop along the California coast on Friday. As much as one inch of rain was expected to fall along the coasts of Washington and Oregon on Friday, with the largest totals falling across the Olympic Peninsula of Washington. Moderate to heavy rain was expected to continue along sections of the front in California as the entire system travels toward the east. Three to six inches of rain could fall across sections of central and northern California on Friday. Rain was also expected to spread across southern California, where two to four inches of rain were possible. In response to the continued rain, flood watches and flood warnings were in effect across sections of central California along with western Oregon and Washington.
Locally heavy snow was expected over the higher terrain of the Sierras in California, with as much as two feet of snow anticipated near the crest. Winter storm warnings and winter weather advisories were continued across the higher terrain of the Sierras in central and northern California along with the mountains of eastern Nevada.
In addition to the heavy precipitation that would continue across the West, the storm would continue to generate strong winds. Southerly winds were expected to continue into early Friday morning across western Washington including the region around Puget Sound and the Seattle-Tacoma metropolitan area. These strong winds would be accompanying the storm's low pressure center as it would travel close to Washington's Olympic Peninsula and into southern British Columbia. A variety of high wind warnings and wind advisories were posted across large areas of Washington, Oregon, California, Nevada, Utah and Arizona.
TEMPERATURE EXTREMES ACROSS THE CONTINENTAL US -- Thursday's lowest temperature was 7 degrees below zero at Crested Butte, CO. Thursday's highest temperature was 79 degrees at Kingsville NAS, TX and Yuma, AZ.
ALASKAN WEATHER -- While partly cloudy skies were found across sections of northwestern Alaska on Thursday afternoon, many of the weather stations across mainland Alaska were reporting cloudy skies or fog. Light snow was also falling across interior and southwestern sections of the 49th State, while rain was reported across the southeastern Panhandle. Satellite images showed widespread low clouds and fog across mainland Alaska. The fog and clouds were situated to the north of a stationary front that stretched along the coastal sections of southern Alaska, running from the Kuskokwim Delta and Bristol Bay in the southwest across the Kenai Peninsula and Prince William Sound to the Copper River Basin in southeastern Alaska before reaching a low pressure center in southern sections of Canada's Yukon Territory. This stationary front separated a relatively warm and humid air mass situated over the Gulf of Alaska from a cold air mass that stretched across most of mainland Alaska. In addition, a weak low pressure center was located over the northern Gulf less than 100 miles to the southeast of the Kenai Peninsula. Southerly winds carrying humid air from over the Gulf of Alaska were flowing over the dome of colder air to the north of the front. Fog and low clouds were the result of this overrunning.
Strong winds persisted across northwestern Alaska on Thursday due to the tight pressure gradient that remained across northern sections of the state between high pressure over the Arctic and lower pressure across the Gulf of Alaska. Wind gusts reached 60 mph over northwest Alaska. Wind gusts to 50 mph were also reported at Whittier along Prince William Sound in south central Alaska.
The lowest overnight temperature in Alaska on Thursday morning was 35 degrees below zero at Deadhorse, while the mid-afternoon highest statewide temperature was 50 degrees at Metlakatla, Petersburg and Wrangell.
HAWAIIAN WEATHER -- Many of the weather stations across the Aloha State reported mostly cloudy skies late Thursday afternoon. In addition, some rainshowers had also developed. The clouds and showers represented the remnants of a weak cold front that had traversed the Hawaiian Islands from northwest to southeast late Wednesday and into Thursday. By midafternoon on Thursday the front had dissipated by the time it passed across the Big Island, leaving only some remnant clouds and showers. With the passage of the front, the light and variable winds strengthened to become moderate northeast trade winds as a weak high pressure cell was passing approximately 700 miles to the north of Kauai. Satellite images showed numerous low cumulus and stratocumulus clouds moving toward the west-southwest across regional waters. These clouds were post frontal. Radar detected some rainshowers traveling across the Big Island and the waters to the south. Additional showers were over Maui and along the windward slopes of Oahu.
The clouds and showers associated with the remnants of the former cold front were expected to remain across the Big Island and Maui into early Friday. The moderate northeast trade winds were expected to weaken as the high pressure cell continues to move eastward away from the islands. Regional winds should become light and variable during the afternoon, leading to possible development of afternoon sea breeze and nighttime land breeze regimes. Another weak cold front was expected to reach the western Hawaiian Islands over the weekend.
The ocean swell that had been responsible for the high surf warnings along the north- and west-facing beaches earlier Thursday had diminished. Therefore, the high surf warnings were replaced by high surf advisories. These advisories, which would run through late Friday afternoon, were for the north- and west-facing coasts of Niihau, Kauai, Oahu and Molokai and for the north-facing shores of Maui.
PUERTO RICO AND US VIRGIN ISLANDS WEATHER -- Partly cloudy sky conditions were reported across Puerto Rico, Culebra and Vieques ranged on Thursday night. Satellite image animations revealed a few clusters of low clouds moving westward across the region, carried along by easterly winds in the low troposphere. In addition, a few thin high clouds were traversing the region from west to east on upper tropospheric westerly winds. Radar detected only a few light to moderate rainshowers moving across the surrounding waters of the Atlantic and Caribbean. The lack of significant clouds and precipitation was due to the relatively dry and stable air mass that remained across the region. Surface winds across the islands ranged from easterly to northeasterly during the evening.
Generally fair weather conditions should remain across the islands on Friday. However, an increase in atmospheric humidity was anticipated over the weekend, which would result in an increase in the chance of showers.
Ocean swell was continuing to propagate across the western North Atlantic and reaching the local waters from the north-northeast. This swell was creating high surf and strong rip current conditions along the Atlantic coastlines of the individual islands. Therefore, a high surf advisory was to continue through early Friday evening for these coasts. The high seas along with east winds with speeds to 20 mph have necessitated the continuation of small craft advisories through early Saturday.
Geminid meteor showers -- Early Sunday morning, the Geminid meteor shower should peak, with between 100 to 120 meteors streaking across the sky every hour. These meteors, which came from an asteroid rather than a comet, appear to radiate from the constellation Gemini toward the northeast in the local sky. Look about 50 degrees above the horizon. Meteor shower gazing conditions should be acceptable as the waning gibbous moon (last quarter) will rise around local midnight. Check NASA Chats for information concerning the program on the Geminids conducted by experts at NASA's Marshall Space Flight Center Saturday night at 11:00 PM EST and during the peak viewing hours (11:00 PM to 3:00 AM EST) .
A TIME OUT -- Today's Daily Weather Summary discussion is the final one for the Fall 2014 course. If you are looking for an alternative description of daily weather, you could try:
http://www.weather.com/news (The Weather Channel)
or
http://www.wpc.ncep.noaa.gov/discussions/hpcdiscussions.php?disc=pmdspd (The National Weather Service's Weather Prediction Center)
DataStreme Daily Summaries and Investigation files will return with the Spring 2015 DataStreme Atmosphere course during Preview Week on Monday, 19 January 2015. Have a happy and safe holiday season! EJH
Several noteworthy "sky" events that will occur during the next several weeks include:
From the files of the Aviation Weather Center, Kansas City, MO and Intellicast
Return to DataStreme Atmosphere website
Prepared by Edward J. Hopkins, Ph.D., email hopkins@meteor.wisc.edu
© Copyright, 2014, The American Meteorological Society.