DATASTREME DAILY SUMMARY

Monday 9 October 2000


00Z Weather Systems


Today is also Yom Kippur and Thanksgiving Day in Canada.

WEATHER OVER THE WEEKEND -- Much of the nation east of the Rockies experienced cold weather over the weekend as a massive high pressure system moved southeastward from Canada. This high pressure system was located on the eastern slopes of the Montana Rockies as of early Friday. By Sunday morning the high pressure system had drifted southeastward into the central Plains and had intensified. At that time, Wichita, KS, Sioux City, IA, Des Moines, IA and Springfield, MO set record high sea-level barometric pressure readings for the month of October, with 1043.0 mb, 1041.0, mb, 1040.7 mb and 1038.0 mb respectively. The leading edge of the cold air was defined by a cold front that moved southward and eastward on the weekend from its initial position across the Ohio and lower Mississippi Valleys on Friday morning. By Sunday morning, with the expansion of the cold air across the country, the cold front had moved well off the Atlantic and Gulf Coasts, with the exception of south Florida, where the front remained across the peninsula.

As the cold air poured southward, numerous daily record low temperatures were either tied or set from the northern Rockies starting on Friday morning and then progressing southeastward across the Plains and Midwest into the Gulf Coast and Southeast by Sunday morning. Dodge City, KS had a record low of 18 degrees on Sunday morning, Omaha (Eppley Field), NE had 22 degrees, Tulsa, OK recorded a 30 degrees low and Little Rock, AR experienced 35 degrees, all the lowest temperatures for so early in the season. Hill City, KS had 14 degrees, which set an October low temperature record. In addition numerous record low high temperatures were also set.

In addition to the record cold, the high pressure produced some early season snowfall. The cold northwesterly winds passing over the relatively warm Great Lakes generated lake-effect snows on the downwind shores of the lakes. Marquette and other locations in Michigan's Upper Peninsula received between 1 to 2 feet of snow over the weekend, commencing on Friday. The 9.8 inches of snow that fell at Marquette on Saturday was not only a daily record, but was also the greatest amount for so early in the season. On Saturday, Milwaukee, WI had 0.2 inches of snow which was the most snow for so early in the season. Interestingly, last winter the first measurable snow did not fall in Milwaukee until mid December, marking the latest occurrence of the first measurable snow. Snow records there extend back to 1870. Other locations that typically receive lake-effect snows also saw snow starting later in the weekend, to include northern Ohio, western Pennsylvania, Upstate New York and even some of the higher terrain of West Virginia.

As the cold front moved south and east in advance of the cold air, rain was found across New England and over the Gulf Coast States on Friday.

Light snow also fell in the cold air that settled across the mountains of west Texas and southern New Mexico. The trace of snow that fell at Lubbock, TX on Sunday was the earliest that snow has ever fallen there.

While much of the nation's midsection experienced cold weather, Tampa, FL tied a record high low temperature of 77 degrees on Friday.

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.

The center of the high pressure system was located over Kansas. Sea-level corrected pressure remained at a relatively high value for this time of year at 1039 mb. Mostly clear skies were found across the Plains and portions of the Southeast. Clouds and lake-effect precipitation continued across portions of northern Lower Michigan, northern Ohio, western Pennsylvania and western New York State. Some of this precipitation was in the form of rain near Lake Erie, while snow fell across the high terrain of Pennsylvania and New York. A large area of rain continued to fall across southern Texas, stretching from near El Paso eastward to Houston. In New Mexico, some of the precipitation was falling as snow, especially in the mountains.

The center of the high pressure is expected to continue drifting to the south and east on Monday, with some weakening of the central pressure possible by Monday evening. With the clear skies and cold air remaining in place, nighttime temperatures are expected to fall to near record levels across a large portion of the nation east of the Mississippi. As a result, freeze warnings were in effect for many areas from the Great Lakes southward across the Ohio and mid-Mississippi and Tennessee Valleys into the southern Plains. Frost advisories were also posted for portions of North Carolina, Virginia and east Texas. Lake-effect precipitation should continue downwind of the eastern Lakes, as northwesterly winds persist through Monday. As a result, lake-effect snow advisories were in effect for the lakeshore counties of northeastern Ohio and northwestern Pennsylvania, as one to two inches of snow were expected. A winter weather advisory was posted for the Sacramento and Guadalupe Mountains of southern New Mexico for a variety of precipitation, ranging from freezing rain, ice pellets (also known as sleet) and snow, while a winter storm warning was in effect for west Texas, to include the Davis Mountains, for much the same weather conditions.

Some precipitation was falling across the Outer Banks of North Carolina and coastal regions of New England on Sunday night. This precipitation represented the western fringe of a larger precipitation shield situated to the northwest of a storm system that developed off the Carolina Coast. The low pressure system formed along the cold front marking the leading edge of the cold air as it moved out into the western Atlantic Ocean. This system is expected to move quickly to the northeast along the front toward the Maritime Provinces, with some precipitation anticipated to continue along the New England coast on Monday.

One of the few places in the East that was relatively warm on Sunday night was South Florida, located south of the cold front. By Monday morning the cold front is expected to have moved southward, reaching the Florida Straits.

Precipitation was spreading across western Washington State and Oregon on Sunday night as a cold front moved into the Pacific Northwest, crossing the Olympic Peninsula. By Monday night, the cold front is forecast to have moved inland, reaching eastern Washington and Oregon, with precipitation spreading southward into northern California. At this time, colder air should cause snow levels to lower to between 5000 and 6000 feet across the Cascades from southern Washington through southern Oregon. A winter storm watch was posted for the Sierras of California and Nevada in anticipation of 6 to 10 inches of snow above 6000 feet on Monday night and Tuesday.

TEMPERATURE EXTREMES ACROSS THE LOWER 48 -- On Sunday, the lowest temperature reported in the continental U.S. was 7 degrees at Cora, WY and West Yellowstone, MT, while Sunday's highest temperature was 101 degrees at Death Valley, CA.

ALASKAN WEATHER -- A low pressure center over the Gulf of Alaska spread rainy and windy weather across the Panhandle and portions of south central Alaska. A weak trough of low pressure was found located along the Arctic Coast, while another trough was located across western Alaska and the Bering Sea. Snow and fog were reported across the North Slope and northwest Alaska, to include Deadhorse, Kotzebue and Nuiqsut. Snow also fell at Bettles and Nenana. A stationary front stretched from Cook Inlet northeastward along the Alaska Range into the Yukon Territory. To the north and west, a weak ridge of high pressure was situated over interior Alaska.

The lowest overnight temperature in Alaska as of Sunday was 5 degrees below zero at Barrow, and the midafternoon highest statewide temperature was 54 degrees at Annette, Klawock and Metlakatla.

HAWAIIAN WEATHER -- A subtropical high pressure cell that was building 1200 miles to the north of Hawaii produced strong northeast trade winds with speeds ranging between 15 to 30 mph across the islands on Sunday. Relatively cloud-free weather was found on the leeward sides of the islands, with few trade showers on the windward slopes of the islands. The central pressure of this high pressure system should reach 1033 mb on Monday, meaning that the strong trade winds should continue, before weakening slightly on Tuesday. Because of the strong winds, small craft advisories were in effect for state waters.

EYE ON THE TROPICS -- Following a fairly active week in the Caribbean and Gulf of Mexico, the North Atlantic basin was quiet on Sunday. In fact, cold air from Canada had moved out across the Gulf behind the cold front that had reached just to the north of the Yucatan Peninsula and the Bay of Campeche as of Sunday night. The remnants of former Hurricane Keith dissipated over the mountains of northern Mexico early Friday. Tropical Storm Leslie passed close to Bermuda before dissipating early Saturday.

In the eastern North Pacific basin, Tropical Storm Olivia continued to move to the northwest away from the Mexican coast. As of Sunday night, Olivia was a minimal tropical storm with sustained near-surface winds of 40 mph, and it was 490 miles southwest of Cabo San Lucas, Mexico, moving to the west-northwest at 10 mph.

REPORT FROM THE FIELD -- Renee Miller, a LIT member from central South Dakota, reported that some badly needed rain fell last week. However, only about 0.25 inches fell and by Friday sunny and cool weather moved into the region.

NEW WORLD WEATHER -- Since today is the Federally observed Columbus Day, check the Monday optional Supplemental Information for a discussion of the weather hazards that confronted Christopher Columbus on his voyages to the New World.


HISTORICAL WEATHER EVENTS - 9 October

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.