DATASTREME DAILY SUMMARY

Wednesday, 1 November 2000


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.

A TALE OF CONTRASTS -- A storm system and accompanying front located over the eastern slopes of the Rockies essentially divided the country into a relatively mild eastern half and a chilly western half on Tuesday evening. Afternoon high temperatures from the high Plains eastward to the western slopes of the Appalachians were above average, with readings across the mid-Mississippi Valley being as much as 20 degrees above the average highs for the end of October. Record high temperatures were either tied or set at Audubon Park in New Orleans, LA (87 degrees), Columbus, GA (86 degrees) and Huntsville, AL (84 degrees). To the west, much of the Great Basin and the Southwest, to include southern California experienced unseasonably cool weather, as afternoon high temperatures were as much as 20 degrees below the climatological average highs across Nevada, Utah and Arizona.

As of Tuesday night, a relatively intense low pressure system was centered over northeast Colorado, along a cold front that extended from Hudson Bay in Canada south-southwestward to the Big Bend Country of west Texas. Relatively strong temperature contrasts remained late Tuesday evening as temperatures aided by southerly winds remained in the 50s and 60s across Kansas and Nebraska east of the front, while to the west of the front, westerly and northwesterly winds contributed to temperatures falling to the upper 30s and low 40s.

SEVERE WEATHER SPREADS ACROSS THE PLAINS -- The region to the east of the developing low pressure system and cold front served as the focal point for severe weather on Tuesday. Thunderstorms developed in the warm and humid air to the east of the front. Wind flow in the upper troposphere also helped produce a condition that enhanced rapid upward motion. As a result, many of the thunderstorms developed rapidly and became severe. Severe thunderstorms moved from eastern Colorado across Kansas and Nebraska into southwest Iowa on Tuesday afternoon and early evening. Numerous tornadoes were spawned by these thunderstorms, with 15 reports made to the Storm Prediction Center of tornadoes that were observed by trained spotters. Some damage, primarily to outbuildings on farms and ranches, was sustained by these tornadoes. Most of the tornadoes were from near Broken Bow, NE to near Goodland, KS. These thunderstorms produced hail that ranged in size to as large as 1.75 inches in diameter, as well as high winds that produced damage. Some of the thunderstorm winds that were estimated to have reached 70 mph near Omaha apparently were associated with a microburst.

The storm system is forecast to intensify and move toward the north-northeast on Wednesday, reaching the Sandhills of north central Nebraska by morning and the Missouri Valley in north central South Dakota by evening. The cold front should sweep eastward across the Plains, reaching the mid-Missouri Valley by evening. Warm, moist air should be drawn northward into the storm system to the east of the advancing cold front. As a result, a slight risk of severe thunderstorms continues through Tuesday night across the Plains from the Rio Grande River of south Texas to central Minnesota. On Wednesday, the regions where a slight risk of severe thunderstorms are expected to occur shift to a northern region over the eastern Dakotas and a southern region that encompasses east Texas, northwest Louisiana and western Arkansas. Between 0.5 and 1.0 inch of precipitation is expected across the Plains on Wednesday.

WINTRY WEATHER HOWLS ACROSS THE ROCKIES -- In the cold air to the west of the storm system and accompanying fronts, snow was falling across the Wyoming Rockies. More than 4 inches of new snow had fallen in Laramie, WY as of early evening As the storm over northeast Colorado intensified, the pressure gradient between high pressure over the Northwest and the low tightened, resulting in strong northwesterly winds that reached 20 mph in many locations. Because of the storm, I-80 was closed on Tuesday night between Laramie and Cheyenne.

As the storm continues to intensify on the lee slopes of the Rockies, snow is expected to continue to the west in the cold air. A variety of snow advisories, winter weather advisories, along with winter storm watches and warnings were in effect for the western Dakotas, eastern Montana, eastern Wyoming and the northern mountains of Colorado. A blizzard warning was also posted for Wednesday to include southeastern Montana and northeastern Wyoming. Blizzard conditions with reduced visibility were anticipated as between 8 to 12 inches of snow were expected east of the Big Horn Mountains in Wyoming, together with winds increasing to as high as 40 mph by midday on Wednesday.

Farther to the south, windy conditions accompanied the cold frontal passage. A high wind warning was posted for the Guadalupe Mountains of southeastern New Mexico and west Texas, as southwest to westerly winds could reach 60 mph in Guadalupe Pass. Frost warnings were issued for southern Arizona, while freeze warnings were issued for portions of northwest and central New Mexico in the wake of the cold frontal passage.

A PESKY STORM -- The storm system that brought as much as 14 inches of snow to northern Maine at the beginning of the week continued to make its presence felt on Tuesday. While the low pressure system was about 500 miles to the east of Boston, MA on Tuesday night, the strong pressure gradient between high pressure over Quebec and the low produced brisk northerly winds over coastal New England. Clouds and light rain were also found along the coast from Maine southward to Cape Cod in eastern Massachusetts.

The storm is expected to continue making a circle over the North Atlantic to the south of Nova Scotia. As a result, windy conditions should continue over coastal New England, with less than 0.25 inch of rainfall by Wednesday evening. Gale warnings for winds between 39 and 54 mph were in effect through Wednesday morning for the New England coast from Montauk Point, NY to Eastport, ME

YESTERDAY'S TEMPERATURE EXTREMES ACROSS THE CONTINENTAL US --Tuesday morning's lowest temperature was 16 degrees at Cut Bank, MT and Truckee, CA, while the highest temperature on Tuesday was 89 degrees at Alice, TX.

ALASKAN WEATHER -- Except for southwest Alaska, most of Alaska was cloud covered. A weakening storm system located in the northern Gulf of Alaska produced clouds and rain across southeast Alaska. The low pressure center was situated near Cordova along an accompanying front that extended from near Kodiak Island northeast across the Copper River Valley in the Yukon Territory. Rain fell at Cold Bay, Cordova, Juneau, Sitka and Yakutat. A weak low pressure center located west of Barrow spread snow and blowing snow across northwest Alaska and the North Slope, to include Kotzebue, Bettles and Deadhorse.

The state's lowest overnight temperature on Tuesday morning was 13 degrees below zero at Umiat. The highest temperature by mid afternoon of Tuesday was 49 degrees at Annette and Ketchikan.

HAWAIIAN WEATHER -- Thin, high-level cirrus clouds spread across the islands on Tuesday afternoon, resulting in filtered sunshine. An easterly wave, representing a disturbance in the trade winds, continued to move west away from the islands. The subtropical high pressure cell responsible for the trade winds was located closer to San Francisco on the California coast than to Honolulu. The winds were expected to become more easterly and weaken to speeds of approximately 15 mph for the remainder of the week.

PUTTING A WRAP ON OCTOBER -- The National Climatic Data Center (NCDC) has produced a list of various noteworthy extremes in temperature, precipitation and snowfall across the United States during the just concluded month of October at http://www.ncdc.noaa.gov/ol/climate/extremes/2000/october/octoberext2000.html. Updates to this list may appear during this upcoming week.

WIND OBSERVATIONS -- For a look at how the horizontal wind direction changes as you go up in the lower troposphere, see the Wednesday optional Supplemental Information on the Ekman spiral.


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/w_sum.html
Prepared by Edward J. Hopkins, Ph.D., email hopkins@meteor.wisc.edu
© Copyright, 2000, The American Meteorological Society.