DATASTREME DAILY SUMMARY

Monday, 30 October 2000


00Z Weather Systems


A "TIMELY" REMINDER -- Over the weekend most of the nation turned the clocks back one hour from Daylight Saving Time to Standard Time. For those who may have missed the excerpts from last Friday's summary discussing the fall time change, please check Monday's optional Supplemental Information .

WEATHER OVER THE WEEKEND -- A low pressure system that intensified last week in the western Atlantic near the Bahamas moved northward over the weekend. While well offshore, the tight pressure gradient between a high pressure cell over the Middle Atlantic States and this low maintained strong winds and high surf along the Eastern Seaboard from Florida north to the Middle Atlantic States. This storm system was considered to be a hybrid, containing characteristics from both tropical and extratropical systems. As it moved northward it intensified as a cold pool of air came off the coast of New England. This interaction between systems brought comparison with a similar situation that produced a major Halloween storm system at the end of October 1991, which was later immortalized in the recently released film called "The Perfect Storm". A westward movement of the current storm brought snow to New England and New York State on northerly winds. By Sunday afternoon, more than a foot of snow had fallen across some of the higher elevations of northern Maine, with lesser amounts in New Hampshire and Vermont. Caribou, ME had 0.83 inches of liquid-equivalent precipitation, which set a daily precipitation record; the station also recorded 8.4 inches of snow, the second greatest daily total in October. Albany, NY had 0.4 inches of snow, setting a daily record and making this October, the fourth snowiest in station history. Central Park in New York City had light snow flurries, marking the first time in 21 years and the seventeenth time in the 131-year record that snow had fallen there in the month of October. Relatively chilly conditions were also reported, as Albany only reached a high temperature of 36 degrees, while Boston, MA had 40 degrees, record low high temperatures for the date at both locations.

Active weather was found across the nation's midsection. Severe thunderstorms produced large hail and winds to 63 mph across central Oklahoma near Oklahoma City on Friday. On Saturday severe thunderstorms produced at least 8 tornadoes across northwest Kansas. High thunderstorm winds caused damage across western Kansas, Oklahoma and Texas, especially in the Panhandle. An injury was sustained when a possible gustnado (or relatively weak gust front tornado) damaged roofs in Lamesa in west Texas north of Midland. Severe thunderstorms were reported across central and east central Nebraska on Sunday afternoon and early evening. These storms spawned tornadoes. Ten reports of tornadoes were filed with the Storm Prediction Center. Hail ranged from 0.75 inches to 1.75 inches near Lincoln.

Powerful storm systems continued to make landfall on the West Coast over the weekend. These storms were accompanied by heavy precipitation that fell as rain at the lower elevations and high altitude mountain snow. On Saturday in northern California, Redding had a record 1.27 inches and Red Bluff had a record 0.81 inches. As of Sunday evening, Monterey and Salinas in central California had received 4.19 inches and 2.31 inches, respectively, which are October record precipitation totals for the two locations. As much as 2 feet of snow fell near Lake Tahoe in the central Sierras. Because the cold air in the upper troposphere produced unstable atmospheric conditions, several thunderstorms were produced. Doppler radar indicated a possible tornado in the San Joaquin Valley of California on Sunday afternoon. High winds associated with these storms also caused high surf along almost all of the West Coast from the Strait of Juan de Fuca to the Channel Islands of southern California.

Elsewhere, high pressure was found across the Southeast, leading to relatively warm and quiet weather. Record high temperatures were either tied or set on Sunday at Mobile, AL (87 degrees), Audubon Park in New Orleans, LA (86 degrees), Tupelo, MS (86 degrees), Pensacola, FL (85 degrees), Memphis, TN (85 degrees) and McAlester, OK (82 degrees).

The Great Lakes States experienced a chilly air mass as high pressure moved across the region. A record low temperature was tied at Traverse City, MI on Sunday morning with 22 degrees.

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 major storm system centered over the Bay of Fundy continued to produce wintry conditions across New England. Strong northerly and northwesterly winds were produced by the tight pressure gradient that developed between high pressure over Ontario and the low pressure center. These winds helped produce wind-chill equivalent temperatures that were in the teens across New England and Upstate New York. Light snow continued to fall across interior sections of Maine, with rain over coastal Downeast Maine.

The storm system is expected to rotate around the Bay of Fundy and the Gulf of Maine on Monday. Precipitation associated with this system should continue across northern New England. As a result, winter storm warnings remained in effect for northern Maine, where 3 to 6 additional inches of snow were possible, which would bring the total snow accumulations to between 12 and 18 inches by dawn Monday. A half inch of precipitation, mainly in the form of rain could fall along coastal Maine in the 24 hours ending on Tuesday morning.

Cool air was pushing southward and eastward across the Great Lakes into the Middle Atlantic and Southeastern States in association with a elongated area of high pressure centered near Saulte St. Marie, ON. This system is expected to drift slowly eastward. As a result of the cool air, coupled with the enhanced nighttime radiative cooling provided for by weak winds and clear skies, a variety of frost advisories and freeze warnings were posted for portions of lower Michigan, east central Indiana, Maryland, northern Virginia and coastal North Carolina.

An occluding storm system located over Nebraska continued to produce rainshowers and thunderstorms across the nation's midsection, stretching from the Red River Valley of north Texas northeastward to the mid-Mississippi Valley near St. Louis, MO and then northwestward to the eastern Nebraska and southwest Minnesota. During the later or occluding stage of the storm, the cold front catches the warm front to form an occluded front at the surface. In this instance, the occluded front stretched southeastward from the surface low pressure system to a point of occlusion in northeast Kansas. At this point, also referred to as the triple point, a warm front continued southeastward into Alabama, while a cold front curved southwestward across the southern Plains into southern Texas.

The low pressure center associated with this occluding system is expected to dissipate by Monday evening over eastern South Dakota. Relatively light amounts of precipitation are anticipated.

A cold front, marking one of the Pacific storm systems that had reached the Northwest, was moving across the Great Basin on Sunday night. With northern portions of the front found on the high Plains of eastern Montana and the southern end of the front in southern California, most of the precipitation was found from southern California into the Snake Valley of southern Idaho. In the warm air to the east of the northern low pressure center, dense fog advisories were in effect for northeastern Montana and western North Dakota.

The northern low pressure center is expected to move eastward into the Plains, accompanied by the cold front that would move across the central and southern Rockies.

The most recent in a series of potent storms that made landfall along the West Coast was located along the California and Oregon borders as of Sunday night. A large area of precipitation associated with this system stretched from central California northward to coastal Oregon and Washington State. In addition to the precipitation, high winds earlier in the day produced seas to nearly 21 feet near Point Arena.

By Monday morning the surface low is forecast to move inland across northern California. Snow advisories were posted across northern California, near Mount Shasta where as much as 6 inches were anticipated for elevations above 3500 feet, across portions of Nevada where 3-5 inches could fall, over southern Utah where 6 inches were forecast and the plateau and rim country of northern Arizona where 4 to 8 inches are possible. Heavy surf advisories remain in effect through Monday for the California coast from Point St. George south to Santa Cruz Island in the Channel Islands. Offshore swells with heights to 18 feet could produce 12 foot surf along the coast north of Point Conception.

TEMPERATURE EXTREMES IN THE COTERMINOUS U.S. -- On Sunday, the lowest temperature reported in the continental U.S. was 14 degrees at Pellston, MI, while Sunday's highest temperature was 89 degrees at Harlingen and McAllen, TX.

ALASKAN WEATHER -- Much of the state was cloud covered on Sunday afternoon, except for the Panhandle in the southeast, the Upper Tanana Valley in the eastern interior and the Yukon-Kuskokwim Delta in the southwest. A developing storm system over the North Pacific was moving toward the central Gulf of Alaska. Another storm system was centered over Kotzebue Sound. A stationary front curved southeastward from this low pressure center across western Alaska to Cook Inlet, before turning eastward to parallel the Gulf Coast and finally cross the northern Panhandle into British Columbia. Relatively mild weather was experienced across western Alaska to the west of the front, with southerly and southwesterly winds. With warm air across southwest Alaska, rain fell at Iliamna, King Salmon and Sand Point. In south central Alaska, rain was reported at Homer, Kodiak and Seldovia, while snow fell at Kenai. To the north and east of the front snow fell at Bettles and Fairbanks in the interior. A weak trough line extended from the low center near Kotzebue northeastward across the North Slope. Snow and fog were reported at Kivalina and Wainwright.

The lowest overnight temperature in Alaska as of Sunday was 15 degrees below zero at Umiat, and the midafternoon highest statewide temperature was 47 degrees at Klawok.

HAWAIIAN WEATHER -- A cold pool of air in the mid to upper troposphere just to the north of Hawaii produced unstable atmospheric conditions on Sunday afternoon. Since the air mass remained moist, clouds and heavy rainshowers along with embedded thunderstorms were found across the islands. Urban and small stream flood advisories were posted for windward Oahu and eastern Maui. The thunderstorms that were near Oahu and Molokai had begun to diminish. Drier conditions are expected across the 50th State on Monday as the upper air disturbance moves away from the islands. Easterly winds reaching 20 mph should also continue.


HISTORICAL WEATHER EVENTS - 30 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.