DATASTREME DAILY SUMMARY

Thursday, 1 November 2001


00Z Weather Systems


WELCOME TO NOVEMBER -- Today is the first day of the month of November, derived from the Latin word "Novem", meaning the number nine, since November represented the ninth month of the year in the old Roman calendar that began at the time of the vernal equinox in March. November is often noted for some major storms.

The following highlights of the national weather have been extracted from the surface weather map for Wednesday night:

A WARM END TO OCTOBER -- Much of the nation experienced a relatively mild Halloween as a broad southerly flow of air brought warm Gulf air northward into the central section of the country. A warm front that extended eastward across the northern Great Lakes from a low pressure center located in eastern North Dakota was the leading edge of the northward moving warm air. The southerly winds across the Mississippi Valley were fairly strong as indicated by the tightly packed isobars over the region.

Wednesday afternoon high temperatures across the western Plains were as much as 25 degrees above average. Record high temperatures were set at Dodge City, KS (87 degrees) and at Amarillo, TX (86 degrees). In addition to the relatively warm afternoon conditions, nighttime temperatures remained elevated. Numerous high minimum temperatures were also tied or set on Wednesday to include in Kansas, at Garden City (60 degrees), Dodge City (59 degrees) and Hays (59 degrees); in Nebraska at Scottsbluff and Sidney (both 42 degrees) and in Wyoming at Cheyenne (45 degrees).

CHILLY, WET WEATHER ACROSS THE NORTHEAST -- An area of rain and snow was found in the cold air across the Northeast. This precipitation and cold air were found to the north and east of the warm front, extending from eastern Lake Ontario across Upstate New York and much of New England. Below average high temperatures were found across the Northeast on Wednesday. Portions of New York State had highs that were 10 degrees below average. Some snow fell particularly at the high elevations across northern New England and Quebec. However, Bangor, ME reported a trace of snow on Wednesday, which was the first snowfall ever recorded on this date.

WINDY CONDITIONS ACROSS THE ROCKIES -- A storm system with trailing cold front moving along the US-Canadian border was generating high winds across the Rockies. Winds gusting to 74 mph brought down tree limbs in the Sangre de Cristo Mountains of southern Colorado on Wednesday afternoon. Earlier, winds gusted to 83 mph near Colorado Springs. High winds with gusts to 71 mph were also reported across Montana east of the Divide.

As the storm system moves eastward across the Prairie Provinces, windy conditions are expected to remain across the western Plains. A high wind warning was in effect through Thursday morning for northeastern Montana as west winds could increase to gusts over 45 mph. A high wind watch was posted through Thursday night for eastern North Dakota and western Minnesota.

WINDY CONDITIONS ACROSS FLORIDA -- Strong easterly winds continued to generate ocean waves that battered the Florida's Atlantic coast, causing beach erosion. The easterly winds were found on the southern flank of the high pressure cell situated off the Middle Atlantic Coast. Heavy surf advisories were in effect along Florida's Atlantic coast from Flagler Beach south to Ocean Reef.

MORE WET WEATHER AHEAD FOR THE PACIFIC NORTHWEST -- Rains appear to be returning to the drought-stricken Northwest. A storm system that moved through the Pacific Northwest on Tuesday brought much-needed rain to the region. In the 24 hour interval ending on Wednesday morning, Kellogg, ID had received a record 0.70 inches of rain. The next storm system is moving toward the Pacific Northwest in the form of a front trailing from a low pressure system in the Gulf of Alaska. This next front is expected to reach the Washington and Oregon coasts on Thursday afternoon. Precipitation associated with this system is expected to reach the coast in advance of the front. Upward of 0.5 inches of precipitation could fall across the Olympics, the Coast Range and the west slopes of the Cascades by Thursday evening.

In addition to the rain, the storm was accompanied by high winds that generated heavy ocean surf. As a result, heavy surf advisories were in effect along the Washington and Oregon coasts from Cape Flattery, WA south to Florence, OR.

THE UPPER AIR -- Inspection of the suite of standard upper air charts for 00Z Thursday revealed several patterns.

TEMPERATURE EXTREMES IN THE CONTINENTAL U.S. -- Wednesday morning's lowest temperature was 12 degrees at Saranac Lake, NY, while the Wednesday afternoon highest temperature was 92 degrees at Borrego, CA.

ALASKAN WEATHER -- A large storm system moving eastward across the Alaska Peninsula spread clouds, precipitation and strong winds over much of southwest Alaska. An occluded front extended southeastward across the Gulf of Alaska into the eastern North Pacific. Snow fell at Bethel, Dillingham and Kenai while rain was reported at Saint Paul and Kodiak. Earlier, westerly winds gusted to over 60 mph at Dutch Harbor. An arctic air mass had spread southward across a large portion of the state. The southern boundary of this air mass was a stationary front that extended eastward from the central Bering Sea to near Dillingham in southwest Alaska and then across southern Alaska to near Valdez and the Wrangell Mountains in Southeast Alaska. Relatively cloud-free skies were reported in the eastern portions of interior Alaska. Snow was reported at Wainwright and Kotzebue.

The lowest temperature in Alaska on Wednesday morning was 17 degrees below zero at Deadhorse and Ft. Yukon. The highest statewide temperature as of Wednesday afternoon was 47 degrees at Annette.

HAWAIIAN WEATHER -- The islands continued to experience northeast trade winds that emanated out of the southern flank of a subtropical ridge of high pressure located to the north of the island. These trades had speeds that ranged between 10 to 25 mph. Trade showers also continued across the windward slopes of the islands. This trade wind weather regime is expected to continue through the remainder of the week. Small craft advisories remained in effect for state waters.

EYE ON THE TROPICS -- After drifting slowly northward along the northeast coast of Nicaragua, Tropical Depression 15 intensified into Tropical Storm Michelle on Wednesday afternoon. By late Wednesday night Michelle, the thirteenth named tropical system of the season, was located approximately 225 miles south-southwest of the Cayman Islands and was moving to the north at 6 mph. Maximum sustained winds were 40 mph. Heavy rain associated with this system continued across the western Caribbean. Michelle is expected to continue moving north toward western Cuba or the Yucatan Channel.

Farther east, Tropical Storm Lorenzo continued to move toward the northeast and lose its tropical characteristics. The last official advisory issued by the National Hurricane Center on Tropical Storm Lorenzo was made early Wednesday morning when the system was 805 miles west of the Azores. Forward movement of the system was to the north-northeast at 32 mph. Maximum sustained winds were 40 mph.

In the eastern North Pacific Tropical Storm Octave continued to intensify while moving toward the northwest. As of Wednesday evening Octave had 60 mph sustained surface winds and was approximately 1280 miles west-southwest of Cabo San Lucas with forward movement to the northwest at 12 mph.

A MILESTONE ANNIVERSARY -- Systematic weather observations were taken on the morning of 1 November 1870 at 24 sites across the nation that were operated by observers in the U.S. Army's Signal Corps. Their observations were telegraphed to Headquarters in Washington, DC so that a national weather map could be drawn. These observations made on that morning were the first large-scale, synchronous (or synoptic) observations taken across the nation by the predecessor of the current National Weather Service.


CONCEPT FOR THE DAY - UPPER AIR CHARTS

Not all weather occurs at the surface. The troposphere (weather "layer" of the atmosphere) and those imbedded weather systems depicted on surface weather maps as Highs and Lows may extend to heights of several kilometers above the Earth's surface. At upper levels, far above the effects of surface friction on wind flow, distinct Highs and Lows usually give way to wave-like air currents that stretch around the globe. Meteorologists have long known that the atmosphere is three- dimensional and the understanding of weather requires knowledge about the atmosphere throughout its breadth and depth.

Meteorologists routinely monitor the atmosphere using essentially horizontal upper-air charts drawn at several different levels. These charts are drawn twice daily based on data collected at 00Z and 12Z by radiosondes launched from a network of stations. Each chart is drawn at a particular pressure level. Constant pressure surfaces are used as radiosondes report the data in terms of pressure, pilots often fly aircraft using pressure altimeters, and meteorological calculations are somewhat easier when expressed in terms of pressure values. A surface of constant pressure undulates slightly in altitude from place to place primarily due to the temperatures of the underlying atmosphere.

An often-used upper-air chart is the 500-mb map. This level is about half way up in terms of atmospheric mass and occurs near an altitude of 5,500 meters (18,000 feet) in the mid-troposphere. Winds at this level correlate well with the movements of large-scale weather features that dominate the lower troposphere. Surface Lows generally travel in the same direction and at about half the speed of the 500-mb winds above them.

For a more complete look at features of various upper air charts available on the DataStreme homepage, see the optional Thursday Supplemental Information .

QUESTIONS:

To be submitted on the lines for Thursday on the Study Guide, Part B, Applications', Week 8 Chapter Progress Response Form, under section B. Daily Summary.

  1. The 500-mb chart represents conditions in the [(lower) (middle) (upper)] troposphere.
  2. Weather systems depicted on surface weather maps [(do) (do not)] extend well into the troposphere.

HISTORICAL WEATHER EVENTS - 1 November

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, 2001, The American Meteorological Society.