DATASTREME DAILY SUMMARY

Monday, 6 November 2000


00Z Weather Systems


WEATHER OVER THE WEEKEND -- The beginning of the weekend was relatively quiet across much of the country except for Texas, where a stationary front separated warm and humid Gulf air to the south from the cooler and drier air of the Plains. With little lateral movement of a stationary front, heavy, flood-producing rains continued across a large section of southern Texas on Friday and Saturday. Lufkin had a record 4.75 inches on Friday, while College Station had 3.65 inches, Waco had 2.90 inches and Austin's Bergstrom Airport had 1.09 inches, also daily record rainfall events. Some locations received more than five additional inches of rain by Saturday. As of Sunday San Antonio had 5.48 inches for the first five days of the month, which makes the current month the fourth wettest November on record. Dallas-Fort Worth Airport had 2.14 inches to establish a new daily record precipitation total on Sunday. By late Sunday, more than 12 inches of rain had fallen since last week near Huntsville in southeast Texas. As a result, flooding was a major problem in places such as College Station which had also received a record 2.46 inches of rain on Thursday and in Junction. At least four fatalities were attributed to the floods.

The Southeast remained relatively warm and dry throughout most of the weekend. As a result, several major wildfires continued over North Carolina and Kentucky. Record high temperatures were either tied or set on Friday across the Southeast in Georgia at Columbus (86 degrees) and Athens (84 degrees), in Alabama at Montgomery (85 degrees) and Birmingham (84 degrees), at Meridian, MS (85 degrees), and in Asheville, NC (76 degrees). The 38 day record dry spell was broken on Saturday at Raleigh-Durham, NC when 0.01 inch rain fell.

A weak low pressure system developed along a cold front that was moving across the Northeast on Saturday. This low produced some light precipitation across New England on Sunday morning.

In the West, cold air poured southward behind a cold front that moved into the Northwest on Saturday morning. Several inches of snow fell across the Denver metropolitan area. Sunday afternoon highs were from 10 to 20 degrees below the climatological average high for the first week of November across the Rockies and Intermountain West.

The Midwest had relatively pleasant and mild conditions over the weekend, as high pressure pushed eastward from the West. Clouds began to move into the region in advance of the storm system in the Plains States on Sunday.

WEATHER FOR THE START OF THE NEW WEEK -- The following highlights of the national weather have been extracted from the surface weather map for late Sunday night.

Two major storm systems over the Plains produced a large area of precipitation across the nation's midsection, extending from the western Gulf coast to the Arrowhead of Minnesota, and from the western Plains to the Mississippi Valley. Most of the precipitation was the result of the northward flow of warm and humid Gulf air ahead of these storm systems. As of Sunday night, one low pressure center was situated over the Red River Valley of eastern North Dakota. An occluded front extended southward to a point of occlusion in eastern Nebraska where a warm front extended southeastward to the vicinity of Kansas City, MO, while a cold front continued southwestward to the Texas and Oklahoma Panhandles. Earlier the region between the warm and cold fronts identified as the warm sector, was the site of severe weather. A tornado and a funnel cloud were spotted late Sunday afternoon near Hastings, NE. Hail with diameters reaching 1.75 inches also fell from severe thunderstorms over south central Nebraska.

A second occluding low pressure system was centered over the Oklahoma Panhandle. An occluded front extended southeastward to a point of occlusion in north Texas, where a warm front extended eastward across the Red River Valley of north Texas and a cold front continued southwestward across west Texas to the Big Bend region. A large region of thunderstorms was found in this system's warm sector, or across most of Texas to the east of the cold front. Some of these thunderstorm cells continued to be quite intense. A slight risk of severe thunderstorms is expected to continue through Monday morning across east Texas. A tornado watch was also in effect to just before daybreak across southwest Louisiana. During Monday, a moderate risk of severe thunderstorms is possible across the lower Mississippi Valley. A slight risk of severe storms could occur as far north as St. Louis, MO. Because of the heavy rains that continued across the Lone Star State, a flash flood watch was continued for numerous counties across the central and eastern portions of Texas, as well as some adjacent counties in southeast Oklahoma and southwest Arkansas.

These storm systems are expected to move slowly eastward on Monday, with the northern low pressure system reaching southwestern Minnesota by evening, while the southern low is forecast to reach northern Missouri. The accompanying precipitation shield should spread across the Mississippi Valley. As much as an inch of rain could fall over the region.

Snow was falling on Sunday night in the cold air across eastern Montana, central Wyoming and the Snake Valley of Idaho. This cold air was associated with a ridge of high pressure centered over Alberta. The snow was the result of upslope motion of the easterly winds across the high Plains. A winter storm watch was in effect for much of North Dakota, and the northern counties of South Dakota. Snow advisories were posted for southeastern and east central Oregon, to include the Blue Mountains. Snow and blowing snow advisories were also in effect for the mountains of southwest Montana, where as much as 6 inches could fall and the eastern Plains of Montana, where 3 to 5 inches are possible.

A storm system east of Cape Cod produced rain across coastal New England along with brisk northwesterly winds. This storm system is expected to move to the northeast, passing to the south of Nova Scotia on Monday. The precipitation over Maine should dissipate by afternoon, however, not before some snow falls across northern Maine.

Another storm system was approaching the Washington State coast. Light precipitation was found across Washington and northern Oregon. This storm system is expected to swing southeastward across California on Monday. In anticipation of this storm moving across the Four Corners area, winter storm watches were posted for Monday night into Tuesday for the southern counties of Arizona and New Mexico. Significant accumulations of snow are possible in the mountains.

UPPER AIR -- The 500 and 300 mb charts for 00Z Monday indicate a large pool of cold air extending through much of the troposphere across the Rockies and Intermountain West. This cold air is reflected not only in the isotherm pattern on the 500 mb surface, but the trough of lower heights on both charts. This height trough over the Rockies causes the upper winds over the West Coast to be diverted southward to Arizona and New Mexico before turning eastward and then curving toward the northeast and north across the Plains. The southwesterly and southerly winds on the east limb of the upper trough contributed to the development and maintenance of not only the surface low pressure systems in the Plains, but the strong to severe thunderstorms across the southern Plains. Winds on the 300 mb surface reached in excess of 100 knots. This core of high winds coupled with the divergence in the winds aloft (also noted by the fanning of the height contours) downstream of this jet core provide the upper tropospheric conditions necessary to draw lower tropospheric air into and upward through the atmospheric column above the surface low pressure center. A ridge of higher heights across the Southeast reflects the warm air across that region of the country.

TEMPERATURE EXTREMES ACROSS THE LOWER 48 -- On Sunday, the lowest temperature reported in the continental U.S. was 13 degrees at West Yellowstone, MT, while Sunday's highest temperature was 86 degrees at Brownsville and McAllen, TX.

ALASKAN WEATHER -- A large area of high pressure located along the Arctic coast was pushing cold arctic air across the North Slope and into interior Alaska. Relatively cloud free skies were found across the region. A stationary arctic front extended eastward from near Bethel to near Yakutat separating the arctic air to the north from milder air to the south. Locations to the north of the Brooks Range had subzero noontime temperatures. The tight pressure gradient between this high pressure cell and a major storm system located over the western Bering Sea produced strong easterly winds with gusts to 40 mph along the west coast. Wind-chill equivalent temperatures fell to near 40 degrees below zero at Anaktuvuk. This storm system also had a trough line that extended eastward across southwest Alaska in the vicinity of Bristol Bay and then to a weak low pressure center in the northern Gulf of Alaska. Clouds and light precipitation associated with this trough were found across southern Alaska. Snow fell at Kenai and Juneau, while rain was reported at Bethel, Cold Bay, Iliamna, Ketchikan and Petersburg. A storm system in the North Pacific Ocean to the south of the Alaska Peninsula was moving northeastward toward Alaska's coast line.

The lowest overnight temperature in Alaska as of Sunday was 31 degrees below zero at Umiat, and the midafternoon highest statewide temperature was 49 degrees at Sitka.

HAWAIIAN WEATHER -- Following the heavy rains at the end of last week, relatively dry, trade wind weather returned to the islands on Sunday afternoon. A large high pressure center was located between the Islands and the California coast. With the continued presence of this subtropical high, the trade wind weather is expected to continue through most of the week. Easterly to northeasterly winds will weaken to about 10 mph by Thursday. Ocean swell generated by a storm system at the western end of the Aleutian chain propagated southeastward to reach the Hawaiian Islands early Sunday. During the afternoon, surf ranging from 10 to 15 feet was reported from the northwest facing shores of Kauai and Oahu. As a result, high surf advisories were posted for the northwest facing shores of all islands.

EYE ON THE TROPICS -- The nineteenth tropical depression of the eastern North Pacific hurricane season developed off the west coast of Central America over the weekend. On Sunday, Tropical Depression 19E became Tropical Storm Rosa as the winds increased. As of Sunday evening, Rosa had sustained surface winds of 50 mph and was moving to the west-northwest at 9 mph 380 miles south-southeast of Acapulco, Mexico.

WINTER AWARENESS -- Several states are observing their Winter Weather Awareness Week during this upcoming week (6-12 November): Arkansas, Iowa, Michigan, Minnesota, Oregon, New Mexico, New York, Vermont, and Wisconsin. Residents of these states should become aware of the hazards associated with winter weather and review the safety oriented materials prepared by their local National Weather Service Offices. Other states will conduct Winter Awareness activities within the next several weeks.

WEATHER AND ELECTIONS -- Tuesday is National Election Day, when the citizens of the United States vote for the electors for a President, a third of the members of the U.S. Senate, the entire U.S. House of Representatives, and various state and local officials. Has the weather affected an election?

According to weather historian, David Ludlum, in his book "The Weather Factor", weather may have played a part in various past Presidential Elections, especially in close elections when only a few thousand votes in key states would have swung the outcome in the other direction. Some people have argued that large voter turnouts occur when the weather is favorable. However, others have argued that when the nation was more rural and more agrarian, if the weather were inclement the number of voters would have increased because the farmers would have had time to vote than if the weather were favorable for late season field work. The voter turnout often times would have been beneficial to one political party at the expense of the other.

Regardless of the weather, exercise your right to vote tomorrow, and encourage others to do so also.

Ludlum, D.M., 1984: "The weather factor." Houghton Mifflin Co. Boston. 275 pp. (ISBN 0-395-36144-3)

STORMS OF NOVEMBER -- The month of November is memorable in the central portion of the country, especially along the Great Lakes, for several powerful storms that have wreaked havoc on the region. For more information, consult the optional Monday Supplemental Information.


HISTORICAL WEATHER EVENTS - 6 November

From the files of the Aviation Weather Center, Kansas City, MO and Intellicast


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URL Address: datastreme/learn/m_sum.html
Prepared by Edward J. Hopkins, Ph.D., email hopkins@meteor.wisc.edu
© Copyright, 2000, The American Meteorological Society.