DATASTREME DAILY SUMMARY

Wednesday, 7 November 2001


00Z Weather Systems


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

BLUSTERY WEATHER CONTINUES OVER NEW ENGLAND -- A storm system located over the Bay of Fundy to the east of Maine continued to make its presence felt across New England. A tight pressure gradient on the west side of the low pressure center with a central pressure of 992 mb continued to produce strong northerly and northwesterly winds across New England. Some light rain also fell across Maine.

The storm system is expected to move off to the northeast on Wednesday, with a gradual relaxation of the pressure gradient over New England. However, with winds that could range from 39 to 54 mph overnight, gale warnings remained in effect for the New England coast from Merrimack River, MA to Eastport, ME.

NOT GOOD BEACH WEATHER IN FLORIDA -- Even though former Hurricane Michelle only brushed by Florida and has since dissipated, the hurricane did help generate ocean swells that have continued to generate the high surf battering Florida's Atlantic coast. In addition, the high pressure system to the north has continued to maintain onshore easterly winds. As a result, heavy surf advisory remained in effect on Tuesday night for Florida's Atlantic coast from Flagler Beach south to Jupiter Inlet. However on the positive side, the rains and clouds have finally dissipated across south Florida.

ANOTHER WARM NOVEMBER DAY IN THE MIDWEST -- High temperatures were above the average highs for this time of year across much of the nation's midsection, extending from the Rockies eastward to the Great Lakes, with the largest departures in the Upper Mississippi Valley and western Great Lakes, where highs were nearly 25 degrees above average. Record high temperatures were either tied or set on Tuesday across the region at Sioux Falls, SD (71 degrees), St. Cloud, MN (70 degrees), La Crosse, WI (71 degrees) and in Michigan's Upper Peninsula at Marquette (66 degrees) and Sault Ste. Marie (58 degrees).

The warm weather across the Upper Midwest was associated with the large high pressure system located over the Southeast. A broad southerly and southwesterly flow of air brought warm air northward from the Gulf Coast. In addition, relatively clear skies across much of the nation's midsection allowed the weak autumn sunshine to help heat the ground. Some of these locales may not see record highs as a cold front approached from the northwest.

UNSETTLED WEATHER ROLLS ACROSS THE NORTHERN PLAINS -- A cold front moving across the northern Plains and into the western Great Lakes was accompanied by slightly cooler air along with rainshowers. This cold front trailed from a storm system over northern Hudson Bay southwestward across Lake Superior, the Upper Mississippi Valley and into the central Plains. A stationary front continues westward to the northern Rockies. The air mass behind the cold front is not exceptionally colder than the air that it replaces. A large band of rain along with some snow was moving eastward across the Dakotas and eastern Montana along and to the north of the stationary front.

A weak low pressure center found near the crest of the wave along the front over the Rockies is expected to develop into an organized low pressure system as it moves eastward across the Plains on Wednesday. By evening this low pressure system should have reached the Upper Mississippi Valley near the Twin Cities. A precipitation shield accompanying this system should spread eastward. Rain should fall across the Dakotas, while snow could fall to the north across the southern Prairie Provinces. Between 0.1 to 0.3 inches of precipitation is expected across the Dakotas into the Arrowhead of Minnesota during the 24 hours ending on Wednesday evening.

ELSEWHERE OUT WEST -- Warm air was found to the south of the stationary front that stretched across the northern Rockies. Record highs were also reached on Tuesday afternoon in Utah at Orem (74 degrees) and Toole (72 degrees). However, to the north, the air was sufficiently cold to support some light snow across the northern Rockies on Tuesday morning. Some additional light snow could fall on Wednesday across the central Rockies in Wyoming and Colorado as the western portion of the stationary front moves southward as a cold front.

UPPER AIR -- Both the 500 and 300 mb charts for 00Z Wednesday maintained a height ridge across the nation's midsection reflecting the warm air that extended upward through much of the troposphere. A relatively deep trough of lower heights was found across the Northeast associated with the cold air circulating around the surface low pressure feature in the Canadian Maritimes. A weak trough was also detected across the northern Rockies. This trough was associated with the low pressure center developing in the northern Rockies and western Plains.

YESTERDAY'S TEMPERATURE EXTREMES ACROSS THE CONTINENTAL US -- Tuesday morning's lowest temperature was 15 degrees at Wisdom, MT, while the highest temperature on Tuesday was 89 degrees at Coolidge, Gila Bend and Bullhead City, AZ and Death Valley, CA.

ALASKAN WEATHER -- Much of mainland Alaska was under the influence of an arctic air mass associated with high pressure over northwest Canada. Midday temperatures found across interior Alaska were in the single digits above and below zero. Cloud cover ranged from scattered to broken across the northern two-thirds of the state. The southern boundary of this arctic air mass was a stationary front that extended from the south central Bering Sea eastward along the Aleutians, then paralleling the southern shore of the Alaska Peninsula and the north Gulf Coast before crossing the northern Panhandle into northern British Columbia. To the south, a large storm system was located over the Gulf of Alaska and the North Pacific Ocean. Overcast conditions along with rain and snowshowers were found across the Panhandle. A tight pressure gradient between the high pressure ridge over northern Alaska and low pressure over the Gulf produced strong easterly winds across western Alaska and the Alaska Peninsula. As result, wind-chill equivalent temperatures at many locations ranged from 30 to 35 degrees below zero. Snow fell at Barrow, Eagle, Northway and Glennallen, while rain was reported at Sand Point and Petersburg. Whittier reported a 22 inch snow cover on Tuesday morning.

The state's lowest overnight temperature on Tuesday morning was 26 degrees below zero at Nuiqsut. The highest temperature by mid afternoon of Tuesday was 45 degrees at Atka.

HAWAIIAN WEATHER -- Showers that were associated with remnants of former Hurricane Octave were approaching the windward coast of the Big Island on Tuesday evening. This swirl of showers was expected to spread across the other islands from late Tuesday into Wednesday. Once the clouds and showers move westward, relatively cloud-free skies are expected to return across the Aloha State near the end of the week. With speeds ranging from 10 to 15 mph, the northeast trade winds have been relatively light as compared with several days ago. The pressure gradient across the islands had relaxed as one high pressure center moved toward the northeast away from the islands, but before the next high which was straddling the Dateline passes to the north by the weekend.

EYE ON THE TROPICS -- Former Hurricanes Michelle and Noel weakened and lost their tropical characteristics on Tuesday. Noel merged with a midlatitude weather system over the north Atlantic near Newfoundland on Tuesday morning. Michelle was moving east-northeastward across the western Atlantic to the south of Bermuda before it had weakened sufficiently so as to not be considered as a threat. Wind gusts reached 40 mph in Bermuda.

MONITORING EL NIÑO and LA NIÑA -- Scientists have suggested that some of the unusual weather patterns that have affected not only the United States, but other countries last year, are linked to an event called La Niña. The La Niña episode has persisted. For more details on how to monitor these phenomena, please read the optional Supplemental Information for Wednesday.


HISTORICAL WEATHER EVENTS - 7 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, 2001, The American Meteorological Society.