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A MAJOR MIDWESTERN STORM SYSTEM -- A strong storm system tracking northward through the Upper Midwest was responsible for a large area of precipitation that stretched from the Southeast and lower Mississippi Valley northward to the Great Lakes then westward across the Great Plains. As of late Monday night the low pressure center, with a central pressure of 993 mb was located over northern Iowa. This system was undergoing occlusion, as an occluded front stretched southeastward into western Illinois, where a warm front extended into the Southeast and a cold front continued southward across the lower Mississippi Valley into the central Gulf of Mexico. A secondary cold front extended southwestward from Missouri into southern Texas. A stationary front extended northward from the surface low pressure center into western Ontario, separating the relatively warm air carried northward across the Great Lakes by southerly winds from the colder air brought southward over the northern Plains by strong northwesterly winds.
The strong pressure gradient, as indicated by the tight packing of the isobars on the surface weather maps, created between high pressure over southern Alberta and the low pressure system generated strong northwesterly winds across the western Dakotas and eastern Montana. Strong southeasterly winds were also found to the east of the storm center over the western Great Lakes, the result of a tight pressure gradient between a high over eastern Canada and the low.
Heavy rains produced several daily precipitation records across the Midwest, to include stations in Illinois at Peoria (1.40 inches) and Springfield (1.19 inches), in Minnesota at Minneapolis-St. Paul (1.54 inches), Rochester (1.12 inches) and St. Cloud (1.09 inches) and in Iowa at Des Moines (0.93 inches) and Dubuque (0.81 inches). Snow was falling to the west of the storm system in the cold air across the Dakotas.
The low pressure center is expected to continue moving northward, reaching central Minnesota by Tuesday morning and northern Minnesota by evening. The cold front is expected to sweep eastward into the western Great Lakes. Between 0.25 and 0.50 inches of liquid equivalent precipitation could fall across the Red River of the North in the 24 hours following Tuesday morning. Winter storm warnings were posted across the northern Plains, covering most of North Dakota, the central and eastern counties in South Dakota, eastern Montana and northeastern Wyoming. Blizzard warnings remained in effect for several counties in northeast Montana and east central Wyoming as winds gusting to between 40 mph and 50 mph, along with several inches of additional accumulation, could reduce visibility to near zero in blowing snow. Winter weather advisories were also in effect for southwestern South Dakota and northeast Nebraska. A winter storm watch was issued for the Red River Valley of northwest Minnesota.
SEVERE WEATHER ACROSS THE SOUTH -- Severe thunderstorms moving along the Gulf Coast ahead of an advancing cold front spawned tornadoes and produced strong, damaging thunderstorm winds. On Monday morning and afternoon damaging winds accompanied thunderstorms in Louisiana. A tornado in Slidell, LA caused some damage during the afternoon. Several tornadoes were reported in the vicinity of Mobile, AL on Monday night. One of these tornadoes caused 4 injuries as 2 mobile homes were destroyed.
The cold front is expected to stall over the central Gulf Coast on Monday. A storm system moving across south Texas could cause the front to become a warm front moving northward by evening. A slight risk of severe thunderstorms continued through Monday night along the Gulf Coast from the Mississippi Delta eastward to the Florida Panhandle. On Tuesday, the region where a slight risk of severe weather could occur expands westward to encompass Louisiana and a large portion of southern Texas.
A COLD WEST -- A cold pool of air remained across the West on Monday. Afternoon high temperatures were below the long-term average highs across the high Plains, the Rockies and the Intermountain West. The greatest departures were centered over eastern Montana and northern Wyoming, where highs on Monday were on the order of 25 degrees below the average highs for the first week of November. Several stations in Wyoming had record low high temperatures, to include Cheyenne (24 degrees), Rawlins (22 degrees) and Laramie (19 degrees). In Arizona, Phoenix had a high temperature of 59 degrees on Monday, which was a daily record low high temperature, and in addition, had 0.49 inches of rain, a record for the date.
A winter storm was moving across southern Arizona and New Mexico in association with several low pressure systems over these two states. Rain fell at low elevations and snow at higher elevations. As much as 8 inches of snow fell in the mountains of southern Colorado near Pueblo on Monday, and 6 inches of snow had fallen in the southern New Mexico mountains at Cloucroft.
This storm system is expected to travel southeastward across west Texas on Tuesday. Between 0.25 and 1 inch of liquid equivalent precipitation could fall on Tuesday across southern Texas eastward into the central Gulf Coast. A winter storm warning was issued for the mountains of New Mexico where as much as 10 inches are expected, while a winter storm watch was posted for the Texas Panhandle and the mountains of west Texas.
A high wind warning was in effect for the Los Angeles Basin.
UPPER AIR -- The mid and upper tropospheric charts of the 500 mb and 300 mb constant pressure surfaces for 00Z Tuesday continue to show height troughs at each level across the West, indicative of a large pool of cold air extending up through essentially the entire troposphere. These troughs have deepened over the 24 hours since Sunday night. The heights of the pressure surfaces within the troughs have fallen as the air continued to cool. In addition, the centers of these height troughs have continued to drift south-southeastward, becoming located over Colorado. A strong northerly wind is found on the west limb of the trough along the West Coast. Jet stream winds at 300 mb reached 120 knots over western Washington and Oregon. To the east of the tough, strong southerly winds were also found over the eastern Plains and the Mississippi Valley. These upper tropospheric jet stream winds were contributing to the maintenance of the surface low pressure system over Iowa and, ultimately, to steering the low toward the north.
TEMPERATURE EXTREMES IN THE LOWER 48 -- The lowest temperature on Monday was 6 degrees at Cut Bank, MT, while Monday's highest temperature was 86 degrees at McAllen and Brownsville, TX.
ALASKAN WEATHER -- A storm system in the southwest Gulf of Alaska produced cloudy weather along coastal Alaska from the Alaska Peninsula to the Panhandle. The low pressure center was located south of Kodiak Island, with an associated front that stretched eastward along the North Gulf coast, then southward along the Panhandle. Snow fell at Skagway, Northway and Juneau, while rain was reported at Saint Paul and Sitka. A second storm system was located over the Bering Sea and was affecting the central and western Aleutians. A large region of high pressure stretched from northern Canada into the Arctic Ocean north of Alaska. As a result, cold air associated with this high pressure center was found across much of interior Alaska, to the north of an arctic front that remained stationary across southern Alaska. Midday temperatures ranged from the minus teens to the positive single digits across the North Slope, while to the south of the Brooks Range, temperatures were in the teens. Relatively cloud-free skies were found from the North Slope and Arctic Northwest across the interior. Snow was falling at Barrow and Deadhorse.
The state's lowest temperature on Monday morning was 29 degrees below zero at Arctic Village. The highest temperature across Alaska as of midafternoon on Monday was 46 degrees at Hydaburg, Ketchikan, Klawock, Metlakatla, Sand Point and Sitka.
HAWAIIAN WEATHER -- A large subtropical high pressure system located over the North Pacific Ocean to the northeast of Hawaii and to the west of San Francisco maintained typical trade wind weather across the islands on Monday afternoon. Relatively clear skies were found across the islands, except for where clouds were associated with the usual trade wind showers on the windward slopes of the islands. The islands experienced east to east-northeasterly trade winds with speeds ranging from 15 to 20 mph. These moderate trade winds are expected to continue through Thursday. High surf advisories remained in effect for the north and west shores of all the islands.
EYE ON THE TROPICS -- In the eastern North Pacific, Tropical Storm Rosa moved to the west on Monday. As of Monday evening, Rosa was stationary in a region that was 255 miles south-southeast of Acapulco, Mexico. Sustained surface winds were estimated to be 65 mph.
Atmospheric motions, from the swirl of leaves across the parking lot to jet streams encircling the globe, are all related. The seemingly vast complexity of weather can be divided into combinations of a relatively few sizes and time ranges for study. Usually, the larger the motion, the longer it will last. In addition, different types of motion have variations in forces that dominate the action. The largest persistent flows across the planet extend high into the atmosphere where friction is small enough to be ignored. The smallest momentary breezes are essentially free of the Coriolis effect.
Meteorologists refer to the largest, most persistent atmospheric motions as part of the planetary-scale. The DataStreme course has thus far concentrated on the high and low pressure systems of the synoptic or macroscale. Smaller weather features such as thunderstorms dominate the mesoscale. The smallest movements of air, such as wind gusts or turbulence, constitute the microscale. For more detail on the traditional arrangement of the subdivisions according to space and time scales, together with their observation strategies, see the Tuesday optional Supplemental Information .
To be submitted on the lines for Tuesday on the Study Guide, Part B, Applications, Week 9 Chapter Progress Response Form, under section B. Daily Summary.
From the files of the Aviation Weather Center, Kansas City, MO and Intellicast