DATASTREME DAILY SUMMARY

Friday, 19 October 2001


00Z Weather Systems


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

COOL WEATHER LINGERS ACROSS THE SOUTHEAST -- The large high pressure system that brought unseasonably chilly weather to the eastern half of the country for much of this past week was positioned along the Middle Atlantic Coast near the mouth of Chesapeake Bay on Thursday evening. Relatively quiet weather with essentially cloud-free skies and weak winds stretched along the Eastern Seaboard from New England south to northern Florida. Southerly winds along with clouds were found to the west of the Appalachians across the Ohio and Mississippi Valleys as a cold front approached from the west.

The air mass associated with this high pressure system has been relatively cool and dry. As a result, enhanced radiative cooling at night has lead to overnight low temperatures that have fallen to record low levels for the last several nights. On Thursday morning record low temperatures were either tied or set at Lynchburg, VA (28 degrees), Asheville, NC (29 degrees), Jackson, KY (34 degrees), in Georgia at Augusta (32 degrees) and Macon (33 degrees), in Alabama at Huntsville (34 degrees) and Montgomery (35 degrees). A record low temperature was also set at Austin, TX (42 degrees) under clear skies. Despite sunny skies, daytime temperatures remained reasonably cool as high temperatures on Thursday were on the order of 5 to 10 degrees below the average highs for mid-October. Farther to the southwest, the high temperature at Lubbock, TX was a record tying 90 degrees.

The high pressure system will drift slowly to the east meaning that the residents along the East Coast need to experience only one more cold night this week. Frost advisories have been posted along the Eastern Seaboard extending southward from Tidewater Virginia to include much of North Carolina, and the western portion of South Carolina. Frost advisories were also posted for the suburbs surrounding New York City. On Friday afternoon the high is expected to be sufficiently far to the east that southerly winds will maintain higher overnight temperatures on Friday night.

CONTINUED WET WEATHER IN SOUTHERN FLORIDA -- A stationary front that remained over southern Florida for another day continued to be the site for continued rainshower and thunderstorm activity. This front had been a cold front that had stalled across the region early Tuesday. Nearly 1.5 inches of rain could fall in the Miami metropolitan area during the 24 hours ending on Friday evening.

A WEAK COLD FRONT MOVES INTO THE MIDWEST -- A cold front trailing from a low pressure system on the western shores of Hudson Bay was moving eastward across the Mississippi Valley on Thursday evening. This front stretched southwestward from eastern Lake Superior to the Texas Panhandle. A band of clouds helped mark the location of the front. With little available moisture, only several light rainshowers accompanied the front. Most of these showers were detected across Michigan's Upper Peninsula and northern portions of Lower Michigan. Since the high pressure cell behind the front consists of a modified Pacific air mass, temperature contrasts across the front are not too significant, representing less than a 10 degree difference. The front represented more of a wind-shift line, where southerly winds were found to the east of the front, while winds to the west of the front were from the west or northwest.

As the front moves eastward across the Great Lakes, an increase in the shower activity is anticipated as southerly winds bring more humid Gulf air northward. Rainfall totals for the 24 hours ending on Friday evening are expected to be on the order of 0.1 inches across the Michigan and adjacent Great Lakes states.

RELATIVELY QUIET WEATHER ACROSS THE WEST -- A large high pressure cell located over the Snake Valley of southern Idaho dominated the weather across much of the West. The clear skies and weak winds near the center of the high allowed for temperatures to fall to record levels on Thursday morning in Oregon at Burns (12 degrees) and Klamath Falls (20 degrees). To the north and northwest of the high pressure center, a prevailing westerly wind is transporting cool moist Pacific air into Washington State. Rain was falling on the western slopes of the Olympics and the northern Cascades as the moist air was lifted. Upward of 0.9 inches of rain could fall by Friday evening over the Olympic Peninsula, with smaller amounts across the other mountains in the Pacific Northwest.

TEMPERATURE EXTREMES ACROSS THE CONTINENTAL US -- Thursday's lowest temperature was 12 degrees at Burns, OR. Thursday's highest temperature was 98 degrees at Borrego, CA.

ALASKAN WEATHER -- A large storm system moved eastward across the Gulf Coast of southern Alaska on Thursday. By late afternoon the low pressure center was located along the coast near Cordova. Widespread clouds and precipitation associated with this system dominated southern Alaska. Snow was reported across south central Alaska, while rain fell over the Southeast. Anchorage received 5 inches of new snow in the 24 hours ending in mid afternoon. Heavy rain was reported at several locations in the 24 hours ending in mid afternoon, to include Port Alexander (2.03 inches), Sitka Fire Station (1.60 inches) and Yakutat (1.52 inches). Cold air lay to the north of a nearby stationary front that stretched eastward from the Alaska Peninsula to southern Yukon Territory. This cold air had spread southward across the state as a large arctic high pressure system centered over the Arctic Ocean northwest of Point Hope built southeastward into interior Alaska. A storm system over the western Bering Sea near Far Eastern Russia was generating strong winds and cloudy skies across the western Aleutians.

The lowest overnight temperature in Alaska on Thursday morning was 11 degrees below zero at Anaktuvuk Pass, while the mid-afternoon highest statewide temperature was 51 degrees at Ketchikan.

HAWAIIAN WEATHER -- High pressure located to the northeast of Hawaii was responsible for pleasant trade wind weather across the islands. Trade winds ranged from 10 to 25 mph. Some trade showers were found along the windward slopes of the islands. A slight weakening of the trade winds is expected over the weekend as the high pressure cell moves toward the southeast.

OFFICIAL WINTER FORECAST RELEASED -- Officials with the National Oceanic and Atmospheric Administration (NOAA) released the official nationwide forecast for the upcoming winter (December 2001 through February 2002) at a press conference on Thursday. Below average temperatures are anticipated across the northern tier of states while the Southwest should experience above average temperatures. While the Great Lakes could expect more lake-effect precipitation, dry conditions are forecast for the Southeast. The Southern Plains should experience warm and wet conditions. Elsewhere, winter temperature and precipitation should average close to long-term climatological "normals".


HISTORICAL WEATHER EVENTS - 19 October

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

20 October

21 October


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Prepared by Edward J. Hopkins, Ph.D.
© Copyright, 2001, The American Meteorological Society.