WELCOME TO DATASTREME - The Daily Summary file will describe the current weather pattern across the United States. 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.
The following discussion is based upon the major weather features appearing on Monday night's surface weather maps:
TRIPLE DIGIT HEAT CONTINUES ACROSS TEXAS -- Few clouds and essentially no precipitation were found across Texas and neighboring states on Monday as the unrelenting dry spell and heat wave continued. Dallas-Ft. Worth experienced another day without rain, extending the record-breaking streak to 66 consecutive days with no measurable precipitation (0.01 inches or greater). For over a month many locations across Texas have experienced hot and dry weather with afternoon temperatures soaring to above 100 degrees, the result of a circulation regime that has favored sunny days and sinking motion, which causes compressional heating of the already hot air. Numerous daily high temperatures were set across the Southern Plains once again on Monday afternoon. Some Texas cities reported their hottest day ever since records have been kept at their respective locations. All-time record high temperatures, regardless of month, were recorded at College Station (112 degrees), Victoria (110 degrees), Austin (110 degrees at both Mabry and Bergstrom sites), San Antonio, TX (109 degrees), Houston Intercontinental (109 degrees) and Corpus Christi (107 degrees) and Galveston (101 degrees). In addition, record high temperatures for the month of September were either tied or set on Monday in Texas at Dallas-Ft. Worth (111 degrees), Waco (111 degrees), Wichita Falls (111 degrees), Lufkin (110 degrees), Tyler (109 degrees), Longview (109 degrees), Del Rio (107 degrees), Abilene (106 degrees) and Beaumount/Port Arthur (105 degrees), in Louisiana at Lake Charles (105 degrees) Baton Rogue (104 degrees) and New Orleans' Audubon Park (101 degrees) and in Arkansas at Texarkana (108 degrees). The readings at Waco and at Dallas-Ft. Worth were also the hottest for so late in the year.
The exceedingly dry conditions coupled with the excessive heat contributed to several wildfires across the Southern States on Monday. One of the largest fires was near Houston, TX.
The heat wave is expected to continue through midweek across Texas before some relief in the form of a cooler air mass could push southward.
COOL AIR INVADES THE MIDWEST -- A cool and dry high pressure system centered in central Ontario to the north of Lake Superior helped bring more fall like conditions to the Midwest on Monday. Winds spiraling in a clockwise fashion around this high pressure feature brought cool and dry air southward across the Great Lakes and into the Midwest and Northeast, replacing the warm and muggy air that had been found across the region at the end of last week and for the start of the Labor Day weekend. The leading edge of this cool air mass could be identified as a cold front that had moved southward on Monday. By Monday evening, this cold front stretched from off the Middle Atlantic coast westward to the Appalachians and then southwestward to the Tennessee Valley before turning northwestward across the Ozarks of northern Arkansas. The change in air mass was noticeable in many locations. Following passage of the cold front, temperatures across the Midwest late Monday afternoon were 15 to 20 Fahrenheit degrees below those at the same time on Sunday afternoon.
The high pressure system is expected to move slowly eastward on Tuesday. With cool, dry air settling across the western Great Lakes, nighttime temperatures are expected to fall into the 30s across the region. Relatively cloud-free skies, coupled with weak winds near the center of high pressure tend to enhance the heat loss from the earth's surface through nighttime radiational cooling. As a result, frost advisories were posted on Monday evening for the possibility of overnight temperatures near 32 degrees for much of Michigan's Upper Peninsula and for several adjoining counties of northeastern Wisconsin.
On Tuesday the cold front is expected to continue moving southward across the Lower Mississippi Valley and the Southeast as the cool Canadian air mass spreads southeastward.
WET WEATHER ALONG THE EASTERN SEABOARD -- Widespread rain and embedded thunderstorms were found across a large portion of the Middle Atlantic and Southeastern states late Monday night. This area of precipitation extended from southern New Jersey southward along the Atlantic Seaboard to southern Florida. Some thunderstorms became severe in northern Georgia near Atlanta and across Tennessee on Monday as high winds caused some wind damage and large hailstones with diameters greater than 0.75 inches were generated. The western edge of the precipitation was along the cold front that lay along the Appalachians. This front helped serve as a lifting mechanism for the generation of the thunderstorms. Rain accompanying the cold front interrupted play at the U.S. Open Tennis Championships in Flushing, NY on Monday afternoon. A trough, or a broad region of low pressure along the coast also contributed to the precipitation. Most of the heaviest rain on Monday night continued to fall across eastern North Carolina. Rain is expected to continue along the coastal Carolinas into Tuesday as the cold front pushes southeastward. As a result of the frequent rain events in this area, flood watches were continued for large portions of much of eastern North Carolina and a portion of South Carolina. Some flooding has already been reported in South Carolina.
SEVERE WEATHER IN THE NORTHERN PLAINS -- Several clusters of thunderstorms moved eastward across Montana and North Dakota on Monday night. Some of these thunderstorms turned severe, as hail reached three-quarter inch diameter and winds gusted to 60 mph. Severe thunderstorms were also reported along the Colorado Front Range south of Denver. A slight risk of severe thunderstorms continues across Montana and North Dakota through Tuesday morning.
COOL WEATHER ACROSS THE NORTHWEST -- An unseasonably cool air mass moved southward across central California. As a result, record low temperatures for the date were either tied or set on Monday morning at Bakersfield (53 degrees), Santa Barbara (51 degrees) and Paso Robles (45 degrees). Farther north, the morning low of 31 degrees at Redmond, OR tied the daily record low temperature.
Precipitation continued along the Cascades of Washington State and Oregon on Monday night. This area of precipitation is expected to move eastward into Idaho by Tuesday morning.
TEMPERATURE EXTREMES IN THE LOWER 48 -- The lowest temperature on Monday was 29 degrees at Bridgeport, CA, while Monday's highest temperature was 112 degrees at Fort Worth, McKinney and College Station, TX.
ALASKAN WEATHER -- Widespread clouds and rain were reported across western Alaska as a result of a strong storm system located in the western Bering Sea to the west of St. Lawrence Island. A front associated with the low pressure system stretched eastward and then southeastward across Nome to near Bethel. A second low pressure system located over the Gulf of Alaska to the west of Yakutat was responsible for clouds and rain across much of Southeast Alaska, as a front associated with this system extended southeastward along the Panhandle. Some of the heaviest precipitation fell at Sitka (1.17 inches in the 24 hours ending Monday afternoon) and Yakutat (0.95 inches). Elsewhere, a large area of high pressure was situated over the North Pacific to the south of Adak Island in the Aleutians.
The state's lowest temperature on Monday morning was 28 degrees at Kenai. The highest temperature across Alaska as of midafternoon on Monday was 61 degrees at Big River Lakes and Kodiak.
HAWAIIAN WEATHER -- A broad region of low pressure to the southwest of the islands helped produce cloudy conditions across Kauai and Oahu on Monday. Clouds should move across the other islands by Tuesday. The islands experienced light winds from the east at about 10 to 15 mph on Monday. These easterly winds, locally called trade winds, are associated with a large subtropical high pressure system located several hundred miles west of the northern California coast. An increase in the speed of the trade winds is expected on Tuesday. In addition, cloud remnants from former Tropical Storm John coupled with trade showers are expected to move across the windward sections of the Big Island and Maui on Monday night.
REPORTS FROM THE FIELD -- If you experience some interesting weather phenomenon that you would like to share with other DataStreme participants as a "Report from the Field", please send email your message to the address below.
Z time is the time along the Prime Meridian, 0 (zero) degrees longitude. Life would be easy if you lived in England because your local time and Z time are the same. But what about where you live? For example, if you are looking at today's 12Z weather map, what time was it in your time zone?
Because you live in the U.S. and the earth rotates toward the east, your local time will be earlier than the local time at the Prime Meridian -- that is, the sun rises in England hours before it does in the U.S. Presently, many of us observe Daylight Saving Time. Therefore, 12Z (noon in England) would be 8 AM Eastern (4 hours earlier than local time in England), 7 AM Central (5 hours earlier), 6 AM Mountain (6 hours earlier), and 5 AM Pacific time (7 hours earlier). However, UTC time does not change seasonally. So when the entire country reverts to Standard Time at the end of October for the winter season and we set our own clocks back one hour, 12Z would then become 7 AM Eastern (5 hours earlier than local time in England) .
A table of time conversions for the U.S. is listed in the DataStreme Homepage User's Guide. For additional Z-time explanation, call up Tuesday's optional Supplemental Information.
To be submitted on the lines for Tuesday on the Study Guide, Part B, Applications', Week 1 Chapter Progress Response Form, under section B. Daily Summary.
From the files of the Aviation Weather Center, Kansas City, MO
Return to DataStreme Homepage
URL: datastreme/learn/t_sum.html
Prepared by Edward J. Hopkins, Ph.D., email
hopkins@meteor.wisc.edu
© Copyright, 2000, The American Meteorological Society.