DATASTREME DAILY SUMMARY

Friday, 27 October 2000


00Z Weather Systems


UNSETTLED WEATHER ACROSS THE WESTERN LAKES -- Thunderstorms rumbled from the Upper Mississippi Valley into the western Great Lakes on Thursday night ahead of a cold front. In the late afternoon, severe thunderstorms produced one-inch hail that fell in western Wisconsin near River Falls. This cold front stretched southwestward from a low pressure system near James Bay to a weak low pressure area over the Arrowhead of Minnesota and then to western Iowa before curving westward to become a stationary front in Wyoming. The cold front was the leading edge of a cooler and drier Canadian air mass that coincided with high pressure centered over northern Manitoba and southwestern Nunavut.

By Friday morning the cold front is expected to have moved eastward across Lake Superior, with the accompanying weak low pressure system centered over northern Lake Michigan. Continued eastward movement should have the front oriented across the eastern Lakes by evening. Precipitation accumulations are expected to be relatively light across the Lakes and Midwest.

THUNDERSTORMS ACROSS THE SOUTHERN PLAINS -- Strong to severe thunderstorms moved across the southern Plains on Thursday evening. Some of these storms became severe, as large nickel-sized hail was reported in south central Oklahoma between Ardmore and Wichita Falls, TX. Locally heavy rains also accompanied these thunderstorms that were associated with a weak trough line extending across the southern Plains. Warm, humid Gulf air brought northward on southerly winds fed these thunderstorms.

Thunderstorm activity was expected to continue through Friday. As much as 0.5 inches of rain could fall across much of Oklahoma and adjoining counties of north Texas between Friday and Saturday mornings. Because this region has received large quantities of rainfall recently, a flash flood watch was issued for portions of the Red River Valley to include counties in southern Oklahoma and north Texas.

WINDY WEATHER ALONG THE EASTERN SEABOARD -- A storm system that intensified over the Atlantic Ocean north of the Bahamas moved slowly northward. Located at least 500 miles east of Jacksonville, FL, this storm system helped produce heavy surf and coastal erosion along the Florida coast. Northeast winds with speeds to 25 mph are expected to continue through Friday morning producing 10 foot surf. Consequently, heavy surf advisories were continued along the Florida coast from Hallandale Beach to Fernandina Beach.

As the storm tracks northward on Friday, the effects of the storm are expected to be felt along the Carolina coast. Gale warnings were posted for the North Carolina coast from Currituck Beach Light to Ocracoke Inlet as winds are anticipated to range from 39 to 54 mph. A heavy surf advisory was also issued for the North Carolina coast from Currituck Beach Light to the North Carolina-Virginia line, extending through early Saturday. Surf to 8 foot heights was anticipated.

ANOTHER FOGGY MORNING -- Dense fog advisories were issued late Thursday night for near coastal regions of New England and the Middle Atlantic states, extending from Massachusetts and Rhode Island, across New York's Long Island to New Jersey, Delaware and Maryland. Visibility was less than 0.25 miles. The fog developed as humid air flowing inland from the ocean becomes saturated as it cools. The region has been dominated by high pressure that enhances the nocturnal cooling.

STORMY WEATHER IN THE WEST -- A series of storms moved into the West Coast, producing windy and wet weather from Washington State southward to southern California. Widespread areas of precipitation were found across the West on Thursday night as one low and accompanying cold front were found in the Great Basin and another cold front was approaching the Washington State coast. The first storm has produced rain and embedded thunderstorms over usually dry portions of the southwest. Some sections of southern and central Arizona could receive as much as one inch of precipitation by Saturday morning, which could cause flooding because of the recent heavy rains. A snow advisory was in effect for the southern Sierras for 6 to 9 inches between Yosemite and Kings Canyon National Parks. The second storm is expected to reach the coast by late Friday night. In anticipation, gale warnings were posted for the Washington and Oregon coasts from Cape Flattery, WA to Point St. George, CA. An inch of rain is expected along the Olympic and Coast Ranges of Washington and Oregon in the 24 hours ending Saturday morning.

TEMPERATURE EXTREMES ACROSS THE CONTINENTAL US -- Thursday's lowest temperature was 18 degrees at Gunnison, CO. Thursday's highest temperature was 87 degrees at Alice, Brownsville, Harlingen and McAllen, TX.

ALASKAN WEATHER -- Several low pressure systems dominated Alaska's weather on Thursday afternoon. One low pressure system was located over the Alaska Peninsula near Cold Bay. Windy conditions were found to the west of the storm as a tight pressure gradient built between the ridge of high pressure over the western Aleutians and the low pressure system. Dutch Harbor reported wind gusts to 59 mph. The storm was also responsible for rain at King Salmon, Iliamna and Cold Bay. On Wednesday, 6 inches of new snow fell at Valdez resulting in a snow cover of 18 inches. A second storm system moved through the Bering Strait and was located near Kotzebue. A nearly stationary warm front extended eastward from this low pressure center along the north slopes of the Brooks Range into the northern Yukon Territory. A cold front trailed southward across the Seward Peninsula into the Bering Sea. A third storm system located near the Queen Charlotte Islands affected the southern portions of the Panhandle. Rain fell at Ketchikan. High pressure over the Chukchi Sea generated a northeasterly onshore flow across the North Slope and northwest Alaska. Snow was reported at such stations as Deadhorse, Wainwright and Kotzebue. On Thursday afternoon, Barrow had the lowest statewide wind-chill equivalent temperature of 13 degrees below zero.

The lowest overnight temperature in Alaska on Thursday morning was 2 degrees below zero at Arctic Village, while the mid-afternoon highest statewide temperature was 47 degrees at Sitka.

HAWAIIAN WEATHER -- A relatively cold upper tropospheric pool of air was moving toward the islands from the east on Thursday. As a result, the air was unstable with the potential for heavy showers that could affect the islands on Friday and Saturday. Northeast to east winds with speeds of 20 mph were expected to continue across the islands through the weekend as the subtropical high pressure system remains to the northeast of the islands. Ocean swell from a storm that intensified near Kamchatka earlier in the week should reach the northwest facing shores of the Hawaiian islands on Friday afternoon and evening. At that time, surf heights should approach 10 feet.

EYE ON THE TROPICS -- In the eastern North Pacific, Tropical Depression 18-E became Tropical Storm Paul. As of late Thursday evening, Tropical Storm Paul had 40 mph sustained near-surface winds and was moving to the west at 14 mph approximately 1015 miles southwest of Cabo San Lucas, Mexico.

"FALLING BACK" THIS WEEKEND -- On this Sunday morning most of the nation will revert back to Standard time after roughly 7 months of observing Daylight Saving Time. Since Arizona, Hawaii, Puerto Rico and the eastern time zone sections of Indiana do not observe Daylight Saving Time, no time change will be needed in those parts of the country. Time changes have been mandated by the U.S. Congress. Following the old adage of "spring ahead, fall behind", you will need to turn your clocks back by one hour to conform with the local time observance.

What does this time change mean to you (other than earlier sunsets)? A change from Daylight Saving to Standard Time does not deduct an extra hour of daylight from the day nor does it affect weather patterns. While the weather will not change because of the time change, the times when you will be able to obtain weather charts will now be one hour earlier. The reason for this earlier time is that the National Weather Service always operates on "Z time" (variously called Greenwich Mean Time or Universal Coordinated Time) which does not observe Daylight Saving Time. Thus, the charts are still produced and transmitted at the same Z time.

As a reminder, do not forget to change, if necessary, the internal clock on your computer from Daylight Saving to Standard Time.


HISTORICAL WEATHER EVENTS - 27 October

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

28 October

29 October


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