WELCOME TO DATASTREME - The Daily Summary file will describe the current weather pattern across the U.S. The Tuesday and Thursday files will also contain the "Concept of the Day" with a question to be answered on the weekly Chapter Response Form. Additional Supplemental Information Files will provide optional background material.
RECORDS CONTINUE TO FALL IN TEXAS -- The vicious combination of heat and drought continued across Texas and neighboring states on Tuesday, producing another set of all-time record high temperatures. All time record high temperatures were either tied or set on Tuesday at Laughlin AFB (115 degrees), New Braunfels (112 degrees), Austin (both Bergstrom and Mabry at 112 degrees), Hondo (112 degrees), Victoria (111 degrees), San Antonio (111 degrees), Corpus Christi (109 degrees), Galveston (104 degrees). New September high temperature records were established at Del Rio (109 degrees), Abilene (107 degrees) and Brownsville (105 degrees).
The region has experienced a persistent atmospheric circulation regime that produces sinking motion in the lower atmosphere, which coupled with a lack of clouds, has contributed to the persistent heat. Sinking motion compresses the air as it descends, resulting in an increase in the air temperature and the lack of clouds permits daytime heating by the sun. Furthermore, this type of circulation regime is not conducive to development of precipitation. A lack of moisture during the last month has also contributed significantly to the occurrence of the high temperatures, since the available sunshine is used to heat the ground and raise the temperature rather than to evaporate surface water.
The cold front that moved southward across the Lone Star State did provide some relief to locations farther to the north. While many locations in Texas experienced triple-digit temperatures on Tuesday, Oklahoma City had a high temperature of 97 degrees, marking the first time in 17 days that the daily high temperature failed to crack the "century" mark. However, no rain fell at Oklahoma City for the last 38 days, which is one day shy of the longest stretch of consecutive days without measurable precipitation (0.01 inch or greater). For comparison, Dallas-Ft. Worth experienced the 67th consecutive day without measurable precipitation.
COOL WEATHER EXPANDS ACROSS THE EAST -- The cool and relatively dry Canadian air mass continued to spread southward and eastward across the eastern half of the country on Tuesday. This air mass accompanied a large high pressure system that had drifted eastward to the Ottawa River Valley separating Ontario and Quebec by Tuesday evening. The extent of the cold air can be seen by the position of the cold front marking the leading edge of the cold air. This cold front had moved southward on Tuesday and by early evening stretched westward from the Carolina coast to east Texas before curving northwestward where the front became stationary over the high Plains of western Kansas and Nebraska.
With weak winds and clear skies, areas near the center of high pressure tend to experience significant nighttime cooling. On Tuesday morning, record low temperatures were set at Mt. Washington, NH (23 degrees), Montpelier, VT (32 degrees) and Binghamton, NY (38 degrees), while at Newark, NJ, the morning low of 53 degrees tied the daily record. By Wednesday morning the center of the high should have drifted slowly eastward to near Montreal, QB. As a result, a variety of frost and freeze advisories have been issued for much of northern New England, a large portion of Upstate New York, and northern Pennsylvania.
RAIN CONTINUES ACROSS THE SOUTHEAST -- Widespread rain continued along and to the south of the cold front that was draped across the Southeast on Tuesday. As of late evening, most of the rain was in the form of steady rain, intermittent rainshowers and embedded thunderstorms covering a region to the south and east of a line running between the Outer Banks of North Carolina southwestward to near the mouth of the Mississippi River in Louisiana. Some locations had several inches of rain. This rain was welcome relief to residents of southern Georgia and Alabama, where a multiple year drought has been extremely detrimental to the region's agricultural interests. However, across the Carolinas, the amount and frequency of the recent rain have created problems in a region that has experienced heavy rain in the last year. Flood watches were in effect across some of the counties of coastal North Carolina.
Thunderstorms developed to the south of the cold front along the Gulf Coast and out into the Gulf of Mexico on Tuesday afternoon. One thunderstorm near Bay St. Louis, MS may have spawned an unconfirmed tornado as trees were destroyed. Other thunderstorms caused wind damage near Houston, TX.
The cold front and accompanying rain are expected to move southeastward into northern Florida by Wednesday morning. During the 24 hours beginning on Tuesday evening as much as 2 inches of rain could fall over portions of north Florida and the Outer Banks of North Carolina.
SEVERE WEATHER RUMBLES ACROSS THE NORTHERN PLAINS -- Several clusters of thunderstorms associated with an area of low pressure developed over the northern Plains on Tuesday. The low pressure system contained multiple centers that stretched from the Black Hills of South Dakota westward along a stationary front across Wyoming into northern Utah. Some thunderstorms became severe as they moved across Montana and into North Dakota on Tuesday afternoon and evening, accompanied by large hail. Some hailstones reached diameters as large as the 1.75 inch diameter. Hail was reported west of Great Falls, MT. These thunderstorms were fed in part by the increased moisture on the southerly flow (or winds from the south) across the Plains. This southerly flow was associated with the development of a low pressure system in Wyoming and the eastward movement of the large high pressure system over the Great Lakes.
By Wednesday morning several low pressure systems along a cold front are expected to have reached the Dakotas. A slight risk of severe thunderstorms continues across Montana and the Dakotas through early Wednesday morning. As much as 0.50 inches of rain could fall by Wednesday evening over eastern North Dakota and northern Minnesota in association with the thunderstorms.
ANOTHER COOL START IN THE WEST -- High pressure off the northern California coast has produced a northwesterly wind flow across the Pacific Northwest. Record low temperatures were set on Tuesday morning in California at Bakersfield (52 degrees) and Red Bluff (50 degrees).
SOME RELIEF -- The recent precipitation in the form of rain and some high elevation snow, coupled with cooler weather, has permitted firefighters to contain some of the wildfires across the West. The National Interagency Fire Center in Boise, ID has posted an updated map of the major wildfires across the nation on Tuesday.
YESTERDAY'S TEMPERATURE EXTREMES ACROSS THE CONTINENTAL US --Tuesday morning's lowest temperature was 21 degrees at Truckee, CA, while the highest temperature on Tuesday was 115 degrees at Laughlin AFB, TX.
ALASKAN WEATHER -- Much of Alaska was cloud covered on Tuesday afternoon, the result of several low pressure systems. One low pressure system located near Nome was responsible for widespread cloudiness and light rain across the western third of Alaska. A front extended southeastward from the low center to near King Salmon before curving southwest to run along the Aleutians. Another storm system was located in the Gulf of Alaska approximately 500 miles south of Kodiak. Winds from the southwest on the east side of the surface low pressure pumped large quantities of moisture into Southeast Alaska and the Panhandle. As a result, heavy rain was reported across Southeast Alaska, with 2.23 inches reported in the 24 hours ending on Tuesday afternoon at Petersburg and 2.08 inches at Sitka. High pressure centered approximately 250 miles south of Adak Island maintained relatively calm conditions across the Aleutians and the North Pacific Ocean.
The state's lowest overnight temperature on Tuesday morning was 27 degrees at Arctic Village and Eagle. The highest temperature by mid afternoon of Tuesday was 62 degrees at Klawok.
HAWAIIAN WEATHER -- A relatively thick layer of clouds with cloud bases higher than 6500 feet altitude remained across Kauai and Oahu on Tuesday. Some rain was reported from these clouds associated with a cold pool of air at these altitudes. The clouds are expected to thin on Wednesday. Winds across the island were relatively light from the east as a subtropical high pressure system was too far from the 50th State to maintain strong trade winds across all the islands. This high pressure system was relatively close to the northern California coast. An increase in the speed of the trades to between 10 to 20 mph is expected on Wednesday. However, the easterly winds brought sufficient tropical moisture westward that heavy rainshowers were reported on Tuesday afternoon over the windward side of the Big Island. The heavy rains were in part due to the topography afforded by the lifting of the air along the slopes of the volcanic summits and in part from the vertical motions of the air associated with afternoon heating. As a result, a flood advisory was in effect for the South Hilo District of the Big Island during the afternoon.
EYE ON THE TROPICS -- While the tropical Atlantic appeared to have no major organized low pressure systems, a low pressure system of tropical origins formed off the west coast of Mexico. This system became Tropical Storm Lane, the twelfth named tropical cyclone (low pressure system) in the eastern North Pacific during 2000 as winds increased to greater than 39 mph. By Tuesday evening Lane was approximately 510 miles west-northwest of Acapulco, Mexico and moving west at 10 mph, with sustained near-surface winds estimated to be approximately 50 mph.
From the files of the Aviation Weather Center, Kansas City, MO and Intellicast
Return to DataStreme Homepage
URL: datastreme/learn/w_sum.html
Prepared by Edward J. Hopkins, Ph.D., email
hopkins@meteor.wisc.edu
© Copyright, 2000, The American Meteorological Society.