WELCOME TO DATASTREME - The Daily Weather 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:
SEVERE WEATHER ACROSS THE MIDWEST -- Thunderstorms along a cold front produced heavy rain, wind and hail over a large section of the Midwest on Monday. On Monday evening the cold front, which at times was analyzed as a stationary front (see insert), trailed from a low pressure center near James Bay southwestward across the western Great Lakes, the Mississippi Valley to the southern Plains before curving westward and then northward over the Oklahoma Panhandle. Several weak low pressure centers were found along the front. This front marked the leading edge of a cooler and drier air mass that extended across the northern Plains from a warmer and more muggy air mass that was found across the eastern third of the country. On Monday afternoon before the cold front passed through, Des Moines, IA tied a record high temperature of 97 degrees. Several other Iowa cities also had record highs in the upper 90s. Roughly 200 miles to the north, Minneapolis-St. Paul had an afternoon high of 82 degrees.
Several clusters of thunderstorms continued as of late Monday night, to include especially strong cells over southern Lake Michigan, central Illinois, southwestern Missouri and southeast Kansas. These areas were under official severe thunderstorm watches. Earlier, many of the thunderstorms turned severe as the Storm Prediction Center received 112 reports of large hail (0.75 inches in diameter or larger) and 113 reports of high winds (54 mph or greater) between Monday morning (at 1200 Z) and midnight. These reports came from a relatively long line that extended along the cold front, from northeastern Wisconsin south-southwestward to north Texas. The largest diameter hail reported was golfball sized (2.75 inches) that fell in and near St. Joseph, MO. The winds produced some damage. Because of the heavy rains, some counties across southern Wisconsin were under flash flood watches. Some locations got struck by two waves of storms. On Sunday evening, heavy rains fell from thunderstorms that moved across western Wisconsin. These storms were responsible for a fatality in Eau Claire, as a man lost his life when the vehicle he was driving plunged into a sink hole in a street created by nearly 8 inches of rain. That western Wisconsin city reported 1.7 inch diameter hail on Monday afternoon.
The northern portion of the cold front is expected to move eastward, passing across Lower Michigan by Tuesday morning and reaching the eastern Great Lakes by Tuesday evening. The western portion of the front will travel slowly southward across northern Oklahoma before stalling and becoming a stationary front across the Sooner State by evening. A slight risk of severe thunderstorms continues into Tuesday morning along and ahead of the front from northern Wisconsin southwestward to north Texas.
THE HEAT CONTINUES ACROSS THE SOUTHERN PLAINS -- Many communities in Texas, Oklahoma, Kansas and southwestern Missouri continued to swelter on Monday as afternoon highs reached triple-digits. Numerous daily high temperatures were either tied or set on Monday. Wichita, KS had a record high of 106 degrees, which was also the highest temperature for so late in the season. Wichita Falls, TX reached 107 degrees.
The weather pattern that has brought the heat has also has been responsible for the dry weather across portions of the southern Plains. Dallas-Ft. Worth did not receive any rain on Monday, marking the 73rd consecutive day without measurable precipitation. Oklahoma City has gone through 44 straight days without rain.
WARM IN THE EAST -- High pressure located off the Eastern Seaboard produced relatively quiet weather across the East. Winds around this high were light and from the south, producing relatively warm and muggy conditions into the Northeast. Widely scattered rainshowers continued across portions of Pennsylvania, New York State and New England on Monday evening.
RELATIVELY QUIET IN THE WEST -- High pressure located over the Great Basin dominated the weather across the Western States.
TEMPERATURE EXTREMES IN THE LOWER 48 -- The lowest temperature on Monday was 27 degrees at Truckee, CA, while Monday's highest temperature was 107 degrees at Lake Havasu City, AZ and Wichita Falls and Lajitas, TX.
ALASKAN WEATHER -- Widespread clouds dominated the weather across Alaska on Monday afternoon. Many of these clouds were associated with two storm systems that affected the state. One storm system was situated over the Bering Sea west of Norton Sound and Yukon Delta, with a front that extended southward from the low pressure center over the eastern Aleutians and the northern Pacific Ocean. A second storm system that was beginning to dissipate was found near the Copper River Basin in southeast Alaska with a weakening front that extended eastward from the Panhandle across British Columbia into the Yukon Territory. This system was responsible for the large fraction of the state's precipitation that was situated across southeast and south central Alaska, to include the Anchorage Bowl. Yakutat had 2.56 inches of rain during the 24 hours ending on Monday afternoon. Windy conditions were found at Skagway where winds from the south gusted to 40 mph. Despite the widespread clouds, several areas experienced breaks in the overcast to include Point Hope, the northern Gulf of Alaska near Kodiak and Kenai and the extreme southern Panhandle. Some snow was reported on Monday morning at Barrow and Fort Wainwright.
The state's lowest temperature on Monday morning was 30 degrees at Anaktuvuk Pass, Nome, Nuiqsut and Umiat. The highest temperature across Alaska as of midafternoon on Monday was 63 degrees at Big River Lakes.
HAWAIIAN WEATHER -- The large high pressure cell located over the North Pacific Ocean approximately 1100 miles north of Honolulu maintained light to moderate trade winds across the islands on Monday. These easterly winds (from the east) circulate around the equatorward flank of the subtropical high pressure system. Trade showers were also reported along the windward slopes of the islands. Some cloud clusters, locally called "screaming eagles", were approaching the windward sides of the islands on Monday evening.
EYE ON THE TROPICS -- A tropical low pressure system identified as Tropical Depression 10 intensified and become more organized off the Carolina coast on Monday afternoon to become Tropical Storm Florence. This system is the sixth named tropical low pressure system (tropical storm or hurricane) in the North Atlantic basin this season. As of late Monday night, Tropical Storm Florence was nearly stationary in the western Atlantic , located approximately 400 miles SSE of Cape Hatteras, NC. Winds were 70 mph.
In the eastern North Pacific, Hurricane Lane weakened and was downgraded to tropical storm status as it continued to drift to the west-northwest off the coast of Mexico. As of Monday evening Tropical Storm Lane had winds of 65 mph (below the 75 mph minimum for hurricanes) and was moving west-northwest at 12 mph, approximately 665 miles west southwest of Cabo San Lucas in Baja California. Storm-generated ocean swell was being propagated northward. Moisture from this system could reach the US Southwest in the next several days.
REPORTS FROM THE FIELD -- Faye McCollum, LIT Leader and AERA from Columbus, GA, reported that some of the foliage on trees in southwestern Georgia has begun to turn color and drop, the result of the prolonged drought. She said that her area has received nearly five inches of much needed rain in the last week, but they remain more than 20 inches below the normals for this time of the year.
Renee Miller, a LIT mentor from central South Dakota reported that while cooler weather has reached the northern Plains, dry conditions continue. The fire danger remains at an all time high and is of major concern especially as hunting season approaches. She also mentioned that despite the hot, dry summer, the garden produce has done well and has good flavor. Her husband has grown two giant pumpkins roughly 1.5 times the size of a bushel basket.
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.
NOTE: This Concept for the Day is a repeat of that which appeared in the previous week's Tuesday Weather Summary.
You will find that all DataStreme meteorological maps and charts are labeled with numbers followed with a "Z", such as 00Z, 12Z, 1915Z, etc. These labels indicate the time of observation in Universal Coordinated Time (UTC). The UTC or "Z" time is used because weather observations must be taken at the same time everywhere to accurately represent the state of the atmosphere. But how can you tell from the reported Z time when the observations were made where you live?
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
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URL: datastreme/learn/t_sum.html
Prepared by Edward J. Hopkins, Ph.D., email
hopkins@meteor.wisc.edu
© Copyright, 2000, The American Meteorological Society.