Because of technical problems at the COMET site, the positions of the fronts are currently not available for the DataStreme maps and the accompanying satellite image-fronts composite. The following discussion is based upon the major weather features that should have appeared on Monday night's surface weather maps:
GORDON CHANGES GUISE -- Widespread rains continuing across the Carolinas and Virginia to the north of a diffuse region of low pressure late Monday night were all that was left of former Hurricane Gordon. The low was located in South Carolina with an occluded front extending eastward to a point off the coast where a warm front continued to the east and a cold front extended southward, reaching south Florida.
Following landfall late Sunday night, Tropical Storm Gordon quickly weakened and by early Monday had been downgraded to a tropical depression. By Monday afternoon, Gordon lost its tropical characteristics, and as a result of the interaction with a midlatitude frontal boundary just to the north of the weakening system, it became more like an extratropical low pressure system. Such a transformation from a tropical low pressure system without fronts into one with fronts is not unusual.
Rainfall accumulations across the Carolinas as a result of Gordon were impressive. Many coastal locations -- to include Mrytle Beach, SC -- received as much as 4 inches of rain. Some flooding due to the excessive rainfall rates was reported from eastern South Carolina and portions of North Carolina. As a result of the clouds and rain, afternoon high temperatures across the Carolinas were suppressed by 10 to 15 degrees below the average high temperatures for the date.
By Tuesday morning the low pressure center is forecast to be in southern Virginia to the west of Norfolk, and by Tuesday night the system should be in the Susquehanna Valley of south central Pennsylvania. Several inches of rain are expected to fall across the Outer Banks of North Carolina, with lesser amounts extending to as far north as New Jersey.
A BIG CHANGE IN STORE -- A low pressure system located across the northern Plains is expected to contribute to some noticeable change in the weather across the Plains and Upper Midwest by midweek. The elongated low pressure system was centered in northwestern Minnesota as of late Monday night. A warm front extended to the east-northeast of the low center across northern Lake Superior, while a cold front trailed to the southwest across South Dakota and the Nebraska Panhandle. A widespread area of rain, showers and some embedded thunderstorms stretched from Michigan's Upper Peninsula to northeastern Nebraska on the southern side of the system and from northern Minnesota westward across the Plains to western Montana on the northern flank.
The main feature of this storm is the temperature contrasts found across the system. Strong southerly and southwesterly winds to the east and southeast of the storm drew warm air northward across the Plains into the western Great Lakes. Afternoon high temperatures across the region were some 20 degrees above the long-term average highs for the date. Record high temperatures were set in South Dakota at Pierre (104 degrees) and Aberdeen (95 degrees), at Marquette, MI (86 degrees), and Duluth, MN (84 degrees). However, northerly and northwesterly winds to the west and north of the storm were bringing colder air southward. Temperatures falling by as much as 15 to 20 degrees were expected following frontal passage.
This low pressure system and trailing cold front are expected to move northeastward on Tuesday, reaching western Lake Superior by morning and a position in northern Ontario by evening. Most of the precipitation, which is expected to fall to the north of the storm, should be relatively light.
MORE RECORDS ACROSS THE WEST -- An offshore wind helped send afternoon temperatures to record levels for a second day in California. Daily high temperature records were reported in Southern California (Cuyama with 102 and Mt. Wilson with 91 degrees), the area surrounding San Francisco Bay (Oakland with 92 degrees and San Rafael with 99 degrees) and in the interior valleys of central and northern California (Red Bluff with 104 degrees; Redding 104 degrees; Sacramento 101 degrees). Brookings, located along the southern Oregon coast, also had a record high of 101 degrees.
A COOL START IN TEXAS -- Clear skies with favorable nighttime cooling conditions permitted overnight low temperatures to fall to record readings in Texas on Monday morning. Austin-Bergstrom, TX had 48 degrees, which was the lowest temperature for so early in the season. Other regional temperatures that either tied or established records included Houston-International (54 degrees), Longview, TX (48 degrees) and Monroe, LA (51 degrees).
TEMPERATURE EXTREMES IN THE LOWER 48 -- The lowest temperature on Monday was 30 degrees at Randolph, UT, while Monday's highest temperature was 113 degrees at Death Valley, CA.
ALASKAN WEATHER -- An elongated ridge of high pressure across southern Alaska accompanied by clear skies and weak winds produced record low temperatures at several locations on Monday morning. King Salmon reported a record low of 26 degrees, while Kodiak fell to 31 degrees. A cold front trailing from a low pressure system located over the Arctic Ocean to the north of Barrow brought precipitation to the northwest coast on Monday morning. Snow spread eastward across the Kobuk and Koyukuk Valleys to Chandalar by early afternoon.
The state's lowest temperature on Monday morning was 14 degrees at Anaktuvuk Pass and Bettles. The highest temperature across Alaska as of midafternoon on Monday was 61 degrees at Big River Lakes.
HAWAIIAN WEATHER -- The elongated ridge of high pressure located to the north of Hawaii produced light to moderate easterly trade winds over the islands on Monday. However, a low pressure system and accompanying front developing to the northwest of the islands should move eastward. As a result, the winds are expected to weaken and become more southeasterly. With a more southeasterly wind direction the warmer weather and increased humidity across the islands should produce an accompanying increase in clouds and showers. The low pressure system is anticipated to generate a northwest ocean swell that could produce high surf along the north shores of the islands by Wednesday.
EYE ON THE TROPICS -- Several tropical waves, or disturbances in the wind flow, were being watched on Monday as potential sites for further strengthening into tropical depressions or even tropical storms or hurricanes. One of these waves that produced clouds and precipitation was located between Hispaniola and Cuba, a second wave was located in the Gulf of Campeche and the third was found along the west coast of Mexico.
Weather at a particular location is like one piece of a jigsaw picture puzzle. Observations of atmospheric conditions at one place, just as a single puzzle piece, cannot reveal the whole picture. Weather systems that typically dominate local weather can stretch over areas thousands of kilometers in breadth. Only through the analysis of local observations made at many locations at the same time can these changing and moving systems be delineated. Weather maps permit (1) convenient reporting of numerous single-site observations, and (2) depiction of existing broad-scale "weather makers" resulting from analysis of the observational data.
Local observations are depicted on weather maps as numbers and symbols plotted in, on, and around circles drawn at each station location, forming a "station model". The station model on which DataStreme maps are based can be seen by clicking on the DataStreme Homepage "DataStreme Weather Map Symbols" . More details are provided in DataStreme Activity 2A and Tuesday's optional electronic Supplemental Information .
Weather systems change over time while moving across the earth's surface. Studying recent and current weather maps allows us to follow the progress of weather systems. These maps provide valuable information to the weather forecaster who needs to know what the weather was and is in order to predict what the weather will be.
To be submitted on the lines for Tuesday on the Study Guide, Part B, Applications, Week 2 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.