DATASTREME WEATHER SUMMARY

Monday 2 October 2000



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WELCOME TO OCTOBER -- The name "October" given to this month is derived from "Octo", the Latin word for the number eight, representing the eighth month of the year in the old Roman calendar.

WEATHER OVER THE WEEKEND -- Many of the nation's residents experienced relatively tranquil weather on this past weekend as major storm systems were absent and relatively high pressure stretched across much of the country.

On Friday morning a large ridge of high pressure centered over Upstate New York produced chilly overnight temperatures across the Northeast. Some locations reported the first frost of the season. More than a dozen daily record low temperature records were either tied or set on Friday morning from Ohio into New England. Bangor, ME and Scranton, PA set a September monthly record with 23 degrees.

This ridge of high pressure remained along the Eastern Seaboard, producing relatively sunny skies during the daytime. A southwesterly wind flow on the western flank of the high pumped mild air northward across the Mississippi Valley. Record high temperatures were set on Friday at Duluth, MN (77 degrees) and on Saturday at Marquette, MI (80 degrees) and Norfolk, NE (91 degrees). Record high temperatures were set across the southern Plains on Sunday with Lubbock (98 degrees) Amarillo (95 degrees) in Texas; Hill City, Dodge City (96 degrees), Garden City (95 degrees) and Wichita in Kansas (94 degrees) and Lincoln, NE (92 degrees). The high at Lubbock and Hill City tied record highs for the month of October.

Severe thunderstorms across southeast Utah and western Colorado on Friday afternoon produced hail as large as 1.75 inches in diameter. Winds along Colorado's Front Range reached as high as the 76 mph reading at Westminster near Denver.

On Saturday a cold front entered the Pacific Northwest and moved southeastward across the Northern Rockies on Sunday. Rain fell across the Rockies into the western Plains. At Missoula, MT a record 0.59 inches of rain fell on Saturday, with an additional 0.84 inches falling on Sunday, which also was a daily record. Lewiston, ID had a record 0.90 inches on Saturday.

A storm system developed off the Florida Peninsula on Saturday morning. This system moved northward along the Gulf Stream to become abeam of the Carolina coast on Sunday.

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.

A cold front moving eastward across the northern Plains into the Upper Mississippi Valley produced rainshowers and thunderstorms across the western Great Lakes and the Mississippi Valley. Some residual showers were also found in the cold air across the Dakotas and Nebraska. This cold front, the leading edge of a cooler Canadian air mass, stretched southward across western Lake Superior and into the Upper Midwest from a low pressure center near Hudson Bay. The cold front curved westward over western Iowa, continuing across the Plains, the northern Rockies and the Intermountain West before crossing the Oregon Coast into the North Pacific Ocean.

The northern portion of this cold front is expected to reach the western shores of Lake Michigan by Monday morning and across Lake Huron and Lower Michigan by evening. Light rainshowers and occasional thunderstorms are expected to develop and move along this front over the western Lakes states. The southern portion of the front is anticipated to move southward to Kansas by Monday evening. Little precipitation is expected ahead of the front as it crosses the Plains. A second cold front is expected to follow, entering the Dakotas by evening.

A storm off the North Carolina coast on Sunday night continued to produce high winds and heavy surf along the Atlantic Coast. This system is expected to intensify as it moves north-northeastward reaching a position well off the New Jersey coast by Monday evening. A gale warning was posted for the North Carolina coast from Surf City to Currituck Beach Light for winds between 39 and 54 mph. A heavy surf advisory for surf between 6 and 8 feet has been issued for the Coast from Flagler Beach, FL to Fenwick Island, DE through much of Monday. Rip currents and beach erosion could result.

Showers and thunderstorms continued across South Florida, the Florida Keys and the Florida Straits along the remnants of an old stationary front. During the late afternoon and early evening, waterspouts were reported offshore. The region of showers and thunderstorms should continue across southern Florida. Between 1.0 and 1.5 inches could fall across south Florida and the Florida Keys on Monday.

An elongated ridge of high pressure extended from New England southwestward to the eastern Gulf Coast. Dense fog that restricted visibility to less than 0.25 miles was beginning to form across central Pennsylvania as air cooled to saturation under the center of the high where winds were relatively light and clear skies promoted surface cooling. Along the Louisiana Gulf coast dense fog formed as an onshore wind from the south brought warm moist air inland over colder ground. The southerly wind was on the southwestern flank of the high pressure ridge.

TEMPERATURE EXTREMES ACROSS THE LOWER 48 -- On Sunday, the lowest temperature reported in the continental U.S. was 28 degrees at Whitefield, NH, while Sunday's highest temperature was 108 degrees at Lake Havasu City, AZ.

ALASKAN WEATHER -- A weak storm system over the Bering Sea spread clouds and rain across Southwest Alaska on Sunday afternoon. The low pressure center was situated in the western Bering Sea with an occluded front extending eastward to the vicinity of the Pribilofs, where a stationary front continued eastward across the Alaska Peninsula and the Gulf of Alaska. A cold front curved south to southwestward across the eastern Aleutians. Farther to the east near the Panhandle, a weak low pressure center was located along the stationary front. Light rain fell earlier on Sunday across Southeast Alaska. An elongated ridge of high pressure centered over eastern Siberia stretched eastward across interior Alaska. This high pressure ridge continued to bring cold arctic air across much of the state. Interior and south central sections also saw breaks in the overcast. Snow fell early Sunday at Nuiqsut and Bettles, while Dillingham and King Salmon reported rain.

The lowest overnight temperature in Alaska as of Sunday was 3 degrees above zero at Cantwell and Denali National Park, while the midafternoon highest statewide temperature was 55 degrees at Dutch Harbor and Atka.

HAWAIIAN WEATHER -- A relatively strong trough of low pressure located to the northwest of Kauai continued to dominate the weather across much of the 50th State on Sunday afternoon. This trough coincided with a wind shift line with southeasterly winds to the southeast of the trough, to include the islands, and northerly winds to the northwest of the trough. Showers and isolated thunderstorms were also found along the trough line. The light southeasterly winds across the islands lead warm and humid conditions to the islands. The winds also lead to local sea breeze circulation regimes as heating over the interior sections of the islands produced an afternoon onshore flow and convective showers over the mountain slopes. This weather regime is expected to remain through the beginning of the week.

EYE ON THE TROPICS -- The North Atlantic basin remained active this weekend. Hurricane Isaac, which had been a major hurricane with winds of at least 130 mph on Thursday night, began curving toward the north and then to the northeast over the weekend. Weakening to a tropical storm occurred late Saturday. During the midday on Sunday when the last advisory for Isaac was issued by the Tropical Prediction Center, Tropical Storm Isaac was moving to the east-northeast at 29 mph and was located 770 miles west-northwest of the western Azores. Sustained surface winds were at 60 mph. By late Sunday the system had begun to lose its tropical characteristics, assuming those of a midlatitude low pressure system.

Former Hurricane Joyce continued moving westward across the tropical Atlantic and into the southern Caribbean. Late Friday, Joyce had weakened to tropical storm status and by Sunday evening it was downgraded to a tropical depression. As of late Sunday night Tropical Depression Joyce with 35 mph winds was approximately 280 miles east of Bonaire in the Netherlands Antilles and was moving to the west-northwest at 15 mph.

In the western Caribbean, Tropical Depression 15 intensified on Friday to become Tropical Storm Keith as winds attained the threshold of 39 mph and by Saturday morning, Keith was upgraded to a hurricane as winds exceeded 74 mph. During the subsequent 24 hours Keith rapidly intensified to a Category 4 hurricane on the Saffir-Simpson Scale as winds reached 140 mph. This major hurricane moved slowly toward the coast of Belize, producing hurricane-force winds reaching in excess of 100 mph along the coast, heavy rains and a storm surge between 9 to 12 feet above normal tidal levels. By Sunday night between 15 to 20 inches of rain had fallen across Belize and portions of the Yucatan Peninsula of Mexico. At least 2 fatalities along with some wind damage and flooding were reported. As of early Monday morning Hurricane Keith was nearly stationary within 55 miles to the south-southeast of Chetumal, Mexico. Sustained surface winds were estimated to be 115 mph. Forecasts indicate that Keith would drift slowly across the Yucatan Peninsula, producing disastrous torrential rains. Weakening is expected as the system is over land. However, reintensification is possible once Keith moves back over the open waters of the southwestern Gulf of Mexico.

REPORT FROM THE FIELD -- Rena Faye Norby, from Belle Fourche-Spearfish area in the Black Hills of southwestern South Dakota reported that the trees were beginning to turn yellow as nighttime temperatures have begun to fall. She said that while Saturday was warm and sunny, passage of the cold front resulted in chilly and cloudy conditions with some scattered rainshowers.

SELECTED SEPTEMBER EXTREMES -- The National Climatic Data Center (NCDC) has produced a list of various noteworthy extremes in temperature and precipitation across the United States during the just concluded month of September at http://www.ncdc.noaa.gov/ol/climate/extremes/2000/september/septemberext2000.html. Updates may be made during this upcoming week.

THE END OF A SEASON -- If you live in the northern portion of the country, the growing season may have already come to an end as cold air masses have moved southeastward from Canada. However, some delightful October days should remain. Read the optional Monday Supplemental Information concerning the end of the growing season and "Indian Summer".


HISTORICAL WEATHER EVENTS - 2 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.