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SEVERE WEATHER HITS THE SOUTHEAST -- Severe thunderstorms traveling across North and South Carolina on Monday afternoon were accompanied by large hail with diameters as large as 1.75 inches and winds reaching at least 60 mph. These thunderstorms were found in the warm sector of a storm system moving across the Southeast. As of late Monday night, the storm system was situated along the Piedmont of south central North Carolina, with a warm front extending to the east toward the Atlantic Ocean and a cold front trailing southward across South Carolina, Georgia and the Florida Panhandle. The warm sector was found in the region between the two fronts to the southeast of the low pressure center. Warm and moist air, ingredients for thunderstorm development, resided in the warm sector that ultimately was situated over the Carolinas, Georgia and Florida. On Monday afternoon, a record high temperature of 87 degrees was established at North Mrytle Beach, SC.
By Tuesday morning the low pressure center is expected to move toward the northeast, reaching a location off the mouth of Chesapeake Bay. The cold front should continue to sweep east toward the coast. A slight risk of severe thunderstorms continues through Tuesday morning for the region occupied by the storm's warm sector covering a portion of south Georgia through the Carolinas.
WET WEATHER ACROSS THE MIDDLE ATLANTIC -- A relatively large precipitation shield was detected to the north of the surface low pressure and frontal system in the Carolinas. The area of rain extended from southern New England to the Ohio Valley. Some of the precipitation amounts were significant, with daily rainfall records set in Kentucky at London with 1.42 inches and Louisville (1.38 inches). A flash flood was issued for the Upper Ohio Valley to include counties in southeastern Ohio, southwestern Pennsylvania and northern portions of West Virginia.
The thick clouds across the Ohio Valley and the Middle Atlantic States helped to suppress afternoon temperatures. Highs for the day ranged between 15 and 20 degrees below the typical values for the date.
As the low pressure system moves northeastward on Tuesday, the precipitation shield accompanying this system is expected to be concentrated along the New England coast, with as much as an inch of rain falling during the 24 hour interval commencing on Tuesday morning.
COOL WEATHER ACROSS THE COUNTRY --- An unseasonably cool air mass spread across a large portion of the country on Monday, contributing to numerous record low minimum temperatures and record low maximum temperatures for the date. Record low temperatures were reported from Oregon, Montana, Colorado and Texas. Record low high temperatures were concentrated across Kansas and Texas. Afternoon high temperatures across the southern Plains and the Ozarks were as much as 20 to 25 degrees below the climatological average high temperatures for the date. As of Monday night a large and sprawling ridge of high pressure stretched from the Lower Mississippi Valley northwestward to the Pacific Northwest, with several distinct centers located over Oklahoma, Wyoming and northern Idaho.
A layer of thick low clouds and fog was found across the recent snow of southern Wyoming on Monday. Afternoon highs were held down by the lack of sun and the snow cover.
A cold front located along the US-Canadian border on Monday night is expected to drift southward on Tuesday. Slightly colder air was expected behind the front as it reaches the Upper Mississippi Valley during the day.
TEMPERATURE EXTREMES IN THE LOWER 48 -- The lowest temperature on Monday was 10 degrees at Wisdom and Lake View, MT, while Monday's highest temperature was 102 degrees at Gila Bend, AZ.
ALASKAN WEATHER -- Extensive clouds covered Alaska as several low pressure systems dominated the state's weather on Monday afternoon. A major storm system that represented the remnant of Typhoon Shanshan was located in the North Pacific south of the Aleutians. Two weak low pressure centers were situated across the mainland, with one along the Arctic Coast near Deadhorse and the other in the southeast near Northway. Snow fell at Wainwright, Bettles and Tanana. Rain fell at Fairbanks and several other locations in the interior. Southerly winds brought generous rain amounts to south central and south east Alaska, with Cordova receiving almost an inch in the 24 hours ending on Monday afternoon. Dense morning fog was reported at many places in the Panhandle.
The state lowest temperature on Monday morning was 19 degrees at Arctic Village and Deadhorse. The highest temperature across Alaska as of midafternoon on Monday was 61 degrees at Petersburg.
HAWAIIAN WEATHER -- A ridge of high pressure located close to the islands on Monday meant that the easterly winds remained relatively light. With relatively weak winds, clouds and showers began developing on the west or leeward side of the islands. An increase in the surf along the northwest facing shores of the islands is expected by Wednesday as the ocean swell approaches from a storm to the northwest of Hawaii. Surf heights could reach 15 feet.
EYE ON THE TROPICS -- Hurricane Isaac continued moving westward across the tropical Atlantic Ocean on Monday. As of late Monday night the system with sustained 105 mph winds was roughly 1280 miles east of the Leeward Islands and moving to the west-northwest at 9 mph.
On Monday a tropical depression that formed earlier in the day near the Cape Verde Islands as a tropical depression had intensified sufficiently to warrant classification as Tropical Cyclone Joyce. This tropical cyclone is the tenth of the season for North Atlantic Ocean. Joyce was following closely to the track of Hurricane Issac.
REPORT FROM THE FIELD -- Matt Hinkin, a LIT Member from Knoxville, TN reported on the welcome rain that fell across East Tennessee on Sunday and Monday. During the previous month, less than 0.25 inches had fallen. However, over the weekend between 2 to 4.5 inches of rain fell. No major flooding was reported. Matt reported "lots of happy farmers and gardeners."
Meteorological satellites are our "weather eyes in the sky". The perspective of space is unique; a satellite image can often provide views of broad-scale weather systems in their entirety. A geosynchronous satellite, high above the equator at an altitude of 23,000 miles and revolving in the same direction as the earth rotates, remains fixed over the same scene on earth. Individual views of the planet below or a rapid sequencing of such images as animation, can display surfaces and clouds associated with weather systems.
Weather satellite sensors are basically tuned to two types of radiation: visible light and infrared. Visible light views are like black-and-white television. Dark surfaces reflect little sunlight and appear dark, while clouds and snow cover are highly reflective, appearing bright. However, clouds, fog, and surface features (forests, mountain ranges, major rivers) are usually visible from space only during daylight hours.
Infrared (heat) radiation is emitted by a surface at a rate directly proportional to its temperature. Consequently, thermal infrared images can be interpreted as temperature maps of the underlying surfaces and clouds. Because heat emissions are continuous, these satellite images are available day and night. Water and ground surfaces are generally warm and appear dark while middle level clouds are cool and look gray. The highest, coldest clouds such as thunderstorm tops are bright white. These temperature ranges may be enhanced by assigning various color schemes for television and computer display.
Specially tuned infrared sensors can even detect invisible water vapor in the middle troposphere. Regions of the atmosphere with little water-vapor content appear dark on "vapor channel" images while high vapor content areas are milky white. Clouds also show as bright white in vapor images.
To view satellite images, and for more details concerning satellite imagery, turn to the satellite views and the Tuesday optional electronic Supplemental Information available on the DataStreme Homepage.
To be submitted on the lines for Tuesday on the Study Guide, Part B, Applications, Week 3 Chapter Progress Response Form, under section B. Daily Summary.
From the files of the Aviation Weather Center, Kansas City, MO and Intellicast
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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.