WELCOME TO DATASTREME - For those participants who are joining us this week, this Daily Summary File represents one of the products that you will routinely use in the DataStreme Project. We - to include myself and those at DataStreme Central - would like to welcome all the participants to this exciting project. I will be responsible for producing this Daily Summary File that describes current and recent weather features of note. On Tuesdays and Thursdays, this file will also contain a "Concept of the Day", which will develop some weather topic in further detail. Two questions related to that topic will appear at the end of this feature for you to answer as part of the weekly materials that you will submit to your LIT mentor by fax. On occasion, I will post a Supplemental Information File. As its name indicates, this file will contain supplementary background material or resource information.
Sincerely,
Ed Hopkins
WEATHER OVER THE WEEKEND -- Portions of the central Gulf Coast received generous amounts of precipitation over the weekend as moisture from a weather disturbance in the Gulf of Mexico was brought northward. Some locations received between 4 and 6 inches of rain over the weekend. Since much of the region extending from Louisiana eastward to southern Georgia has been under a prolonged drought, this rain was welcome. While most of the precipitation was associated with non-severe thunderstorms, some wind damage was sustained in severe thunderstorms that moved across the Louisiana Gulf Coast on Friday afternoon. Much of the rain was associated with the remnants of a short-lived tropical depression, identified as Tropical Depression Nine, which formed off the Louisiana coast on Friday night, and then dissipated by early Saturday morning. The broad air flow carrying the moisture and the rain northward into the Southern states was associated with the wind circulation around the western limb of a large high pressure cell located along the Eastern Seaboard.
In the Pacific Northwest, the cold front that moved onshore late Thursday continued eastward across the northern Rockies on Friday and traveled across the northern Plains on Saturday, reaching the Upper Mississippi Valley and western Great Lakes by Sunday morning. Some severe weather was reported with this advancing cold front. On Sunday morning severe thunderstorms produced large hail and high winds in northern Iowa and the Fox Valley of east central Wisconsin. Earlier, high winds occurred near Glacier National Park in northwestern Montana. In the cold air behind the cold front, Redding, CA experienced a record-tying low temperature of 53 degrees on Friday morning, while on Saturday morning Wenatchee, WA had a record low temperature of 40 degrees.
On Friday severe thunderstorms were reported in Arizona, Utah, Colorado, Nebraska and South Dakota.
On Sunday afternoon a large region of the southern Plains from Texas north into Kansas once again reached triple digit high temperatures following a respite of several days at the end of last week. Fortunately, most of the temperatures reported on Sunday were several degrees less than what was encountered at the beginning of last week. Numerous daily record high temperatures were either tied or exceeded on Sunday afternoon, with a dozen being at or above 100 degrees. Wichita Falls set a record high of 104 degrees while San Angelo and Midland reached 101 degrees. At Dallas-Fort Worth, the record-tying high of 100 degrees marked the sixth day in September to have had 100 degrees or higher -- a number of days which also ties a record set in 1951. In addition to the heat, some locations in north Texas did not see any measurable precipitation. Sunday marked the 72nd consecutive day that Dallas-Ft. Worth has not had measurable rain. Elsewhere, Tampa, FL tied a daily record high temperature with 94 degrees on Sunday afternoon. Severe thunderstorms with large hail and damaging winds were reported in Tucson, AZ late Sunday afternoon.
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 large complex of rainshowers and thunderstorms extended from Lake Ontario southwestward along the western slopes of the Appalachians to near the Cumberland Gap in western Virginia. More widely scattered thunderstorms were found across the Ohio and lower Mississippi Valleys, as well as the Gulf Coast. These storms were found on the western flank of a large elongated low pressure center that stretched from the Canadian Maritime Provinces southwestward to the western Carolinas and northeast Georgia. Southerly winds were found across much of the region as part of the clockwise circulation around the high pressure center. These winds from the south transported warm moist air northward to help feed these storms.
Rainshowers and imbedded thunderstorms are expected to continue across the eastern portions of Lake Ontario, as well as along the Appalachians to as far south as the eastern and central Gulf Coasts on Monday. Between 0.25 and 0.50 inches of rain could fall between Monday and Tuesday mornings.
Additional thunderstorms were also located along a nearly stationary cold front across Iowa and western Wisconsin on Sunday night. This stationary front trailed southwestward from a large storm system near Hudson Bay across Lake Superior, the Upper Mississippi Valley and into a region of low pressure across the Plains in Nebraska. This stationary front marked the boundary between warm and humid air located across the Mid-Mississippi Valley from cooler and drier air found across the western Lakes, the Upper Mississippi Valley and the northern Plains. Temperatures late on Sunday night across southern Wisconsin remained in the mid to upper 70s, while several hundred miles to the north of the front, northern Minnesota reported temperatures in the upper 50s. Some of these thunderstorms were severe with large hail and high winds reported from northern Iowa, southern Minnesota and western Wisconsin on Sunday evening. One report of 2.50 inch diameter hail was made from near Rochester, MN. Winds also caused damage in central Wisconsin west of Wausau. Several of these thunderstorms across western Wisconsin produced flash flooding because of the excessive rainfall rates. In Chippewa Falls, 1.71 inches of rain fell in 25 minutes, while a weather spotter in a neighboring county had 2.15 inches in 45 minutes.
On Monday morning a low pressure center is expected to track northeastward along the stationary front from South Dakota. As a result, to the east of this advancing low, southerly winds (from the south) should turn the front across the Upper Mississippi Valley and the western Great Lakes into a warm front. By Monday evening this low pressure system is expected to reach northeastern Wisconsin. To the west of the low, northerly winds should cause the stationary front to become a cold front across the Plains. A slight risk of severe thunderstorms is expected to continue through Monday morning across Wisconsin, southern Minnesota and northern Iowa, in the region along and to the south of the front. The area with the slight risk of severe thunderstorms is expected to expand eastward and southward during Monday, to include much of Lower Michigan, northern and west central Illinois, most of Iowa and northern Missouri. As much as an inch of rain could fall in portions of eastern Wisconsin and portions of the Mid-Mississippi Valley between Monday morning and Tuesday morning.
Farther west, a large area of rain was reported across Montana east of the Continental Divide on Sunday night. This area of precipitation was to the north of a stationary front that contained several weak low pressure centers and to the east of a low pressure system that had moved eastward from the coasts of Washington State and British Columbia. This precipitation was expanding eastward into western North Dakota.
Several thunderstorms were found in southern Arizona. These were in association with the low pressure center that was located in the lower Colorado Valley.
TEMPERATURE EXTREMES ACROSS THE LOWER 48 -- On Sunday, the lowest temperature reported in the continental U.S. was 23 degrees at Stanley, ID, while Sunday's highest temperature was 107 degrees at Death Valley, CA.
ALASKAN WEATHER -- A complex storm system with several low pressure centers dominated the weather across a large section of Alaska on Sunday afternoon. One low pressure center was located near Norton Sound and the Yukon Delta in western Alaska while another low pressure center was situated near Cook Inlet and Kenai. A warm front extended southeastward from this latter low pressure center across the northern Gulf of Alaska, while a cold front trailed southwestward across the north Pacific Ocean. Much of Alaska was cloud covered, except for some breaks in the overcast over Point Hope, several areas north of the Alaska Range, south of the Brooks Range and east of Fairbanks. Rain fell across south central Alaska and the Anchorage Bowl. Another storm system was located over the western Bering Sea just to the east of Kamchatka.
The lowest overnight temperature in Alaska as of Sunday was 21 degrees at Eagle, and the midafternoon highest statewide temperature was 60 degrees at Klawok.
HAWAIIAN WEATHER -- A large subtropical high pressure system located approximately 1200 miles to the north of Honolulu produced a typical summertime trade wind weather regime over the 50th State on Sunday. Winds on the equatorward flank of this high pressure system are from the east and are typically called trade winds. These trade winds had wind speeds of approximately 20 mph. With the exception of the clouds and light trade showers that were confined primarily to the windward slopes of the Big Island, relatively clear skies prevailed over the islands. Some slackening of the wind speed is expected later in the week as the subtropical high weakens.
Earlier on Sunday small craft advisories were in effect for all state waters, but these advisories were lowered just before sunset.
EYE ON THE TROPICS -- At the end of last week Tropical Storm Lane, the twelfth named tropical system (tropical storms and hurricanes) with near-surface winds greater than 39 mph, had weakened to tropical depression status. However, over the weekend the system reintensified and became a hurricane. As of Sunday night Hurricane Lane was located 400 miles west-southwest of Cabo San Lucas at the tip of Baja California and moving west-northwest at 10 mph. Sustained near-surface winds were approximately 85 mph. Ocean swells generated by the hurricane are expected to propagate northwestward along the Mexican Coast and could produce heavy surf along the south-facing coasts of Southern California within the next two days. Clouds from Lane were streaming northeastward across the Gulf of California into southern Arizona. Additional moisture could continue to flow northward from Lane into the Southwest.
AN INVITE -- If you witness some interesting weather phenomena or would like to share some weather-related experience with others in the DataStreme Project, we cordially invite your contributions. Please email these to the address appearing below. Some of these may appear in the section titled "Reports from the Field".
From the files of the Aviation Weather Center, Kansas City, MO and Intellicast
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Prepared by Edward J. Hopkins, Ph.D., email
hopkins@meteor.wisc.edu
© Copyright, 2000, The American Meteorological Society.