AN ACTIVE FRONT -- The nearly stationary front that extended with an east-west orientation across the eastern two-thirds of the country on Wednesday produced some active weather as several low pressure disturbances moved along the front. The front separated a cool Canadian air mass over the Midwest from a warmer air mass across the South, and stretched from the New York metropolitan area westward to the Texas Panhandle. Low pressure disturbances moving along the front distorted the front, turning it locally either into a warm front or cold front.
Thunderstorms moving along the front produced severe weather in at least two separate regions, one in the Midwest and the other in the Northeast. Hail producing thunderstorms moved from the St. Louis metropolitan area of Missouri eastward across southern Illinois and into southern Indiana on Wednesday afternoon. Golf ball size hail (1.75 inches in diameter) was reported at St. Charles, MO.
Thunderstorms with high winds were reported across eastern Pennsylvania near Philadelphia, central New Jersey and portions of southern New York State near Binghamton. These high winds were responsible for uprooting trees and felling tree limbs. An unconfirmed tornado near Trenton, NJ caused tree and chimney damage.
Rain and thunderstorms continued on Wednesday night primarily along the north side of the front in an area that stretched from the Middle Atlantic States across the Ohio and mid-Mississippi Valleys westward to Kansas. The front is expected to remain relatively stationary through the first part of Thursday, then as a cold air mass pushed southeastward across the Plains, the western portion of the front is forecast to move southward into north Texas. A risk of severe thunderstorms is anticipated along the front in a region that extends across the Mississippi Valley. With heavy rains having fallen and more anticipated, a flood watch was posted for east central Illinois. The heaviest rain on Thursday is expected across the eastern Lakes and into New England, with as much as 1.5 inches possible.
SNOW RETURNS TO THE NORTHERN PLAINS -- The cold air moving southeastward into the country from northwest Canada was sufficiently cold to support snow. Snow was falling in association with a weak low pressure system in North Dakota, with an inch accumulation near Minot late Wednesday night. High temperatures from the Upper Mississippi Valley to the northern Rockies were below the long term average highs for the date, with some locations in South Dakota and in Montana having highs that ranged between 20 to 30 degrees below average. In Montana, Cut Bank reported a record low of 18 degrees on Wednesday morning, and by late Wednesday night, the temperature at Billings, MT fell to 28 degrees, setting a new low temperature record.
On Thursday the snow is expected to move southward across the Black Hills and eastward into northern Minnesota. Cold air should continue southward across the Plains on Thursday, with the leading cold front pushing south into north Texas.
THE SOUTH CONTINUES TO SWELTER -- Many areas south of the stationary front experienced another day of unseasonably warm weather. Afternoon high temperatures were between 10 and 20 degrees above the average highs for the date in Texas. Record high temperatures were either tied or broken on Wednesday in Texas at Wichita Falls (97 degrees), Lubbock (96 degrees), Midland (96 degrees) and El Paso (95 degrees), and at Ft. Smith, AR (94 degrees).
With Tropical Storm Keith intensifying in the southern Gulf of Mexico (see below), a tropical storm watch was posted for the lower Rio Grande Valley in the vicinity of Brownsville, TX. This watch serves to advise the public that a tropical system with sustained winds between 39 and 54 mph could strike within 36 hours.
THE RAINS FINALLY LEAVE SOUTH FLORIDA -- Following an extended period of several days of heavy rains, residents of south Florida finally saw an end to the rains. More than 18 inches of rain fell in Miami metropolitan area since the storm began. On Tuesday a low pressure area developed along the remains of a cold front. This low moved to the east and intensified over the Gulf Stream. By Wednesday night this low pressure system was identified as Subtropical Depression Number 1. This system, with characteristics that differ from those systems that develop in the tropics, is expected to move eastward.
TEMPERATURE EXTREMES IN THE CONTINENTAL U.S. -- Wednesday morning's lowest temperature was 11 degrees at South Pass City, WY, while the Wednesday afternoon highest temperature was 103 degrees at Death Valley, CA.
ALASKAN WEATHER -- A storm system moving across the North Pacific toward the western Gulf of Alaska spread rainy and windy conditions across the Alaska Peninsula and Kodiak Island on Wednesday afternoon. Kodiak had approximately 0.5 inches of rain between morning and midafternoon, together with winds gusting to almost 30 mph. A cold front trailing southwestward from a storm system over the Arctic Ocean produced gusty northerly winds, falling temperatures and snow along western portions of the Arctic coast. Snow was also reported at Tin City, Barrow, Deadhorse and Galena.
The lowest temperature in Alaska on Wednesday morning was 5 degrees at Chandalar Lake and McCarthy. The highest statewide temperature as of Wednesday afternoon was 52 degrees at Annette, Hydaburg and Ketchikan.
HAWAIIAN WEATHER -- The strengthening of an east-west oriented ridge of high pressure approximately 600 miles north of Hawaii has meant a return to more typical trade wind weather across the islands. Light to moderate northeast trade winds are expected to continue into the weekend, along with relatively cloud-free skies and widely scattered light trade showers. Surf, from swell generated by a South Pacific storm, continued to affect the south-facing island shores with heights ranging from 4 to 6 feet. Thus, high surf advisories continued along the south shores of the islands.
EYE ON THE TROPICS -- After moving out over the warm waters of the Bay of Campeche from its travel across the Yucatan Peninsula, Tropical Depression Keith intensified and became a tropical storm once again on Wednesday. By early Thursday morning, Keith was 155 miles east-southeast of Tampico, Mexico and movement was to the west-northwest at 13 mph. Sustained near-surface winds were estimated to be 70 mph. Forecasts are for Keith to move toward the northwest and intensify to hurricane status before making landfall along the Mexican coast near the end of the week. Residents of south Texas have also been advised of the potential for storm-force winds (see above).
In the eastern North Pacific, Tropical Storm Olivia had satellite estimated winds of 65 mph, and it was moving to the west-northwest at 6 mph, at a distance of 530 miles south-southeast of Cabo San Lucas on Mexico's Baja California.
Humans have used the idea of time to mark past experiences and anticipate future happenings. To quantify time, we have traditionally used observable periodic natural phenomena, such as the daily and yearly paths of the apparent sun through the sky and the monthly phases of the moon. The sun is especially important as its uneven heating distribution drives weather systems. The orbital points of the solstices and equinoxes define portions of the year in terms of the solar input into the Earth's energy balance, yielding the so-called astronomical seasons. From the viewpoint of the astronomical seasons, we are in early fall, since astronomical autumn started two weeks ago with the passage of the Autumnal Equinox and will continue to the Winter Solstice during the third week of December.
Similar to the astronomical seasons, we can define meteorological seasons that are meant to fit our calendar as well as the temperature cycle. These seasons are for meteorological observing and forecasting purposes and they are more closely tied to our monthly civil calendar. With this designation, we are now in the middle of meteorological fall. The current transition interval, "autumn", between the year's warmest and coldest portions of the year can be closely linked to the calendar months of September, October and November. We can also have Winter Outlooks and monthly and seasonal averages and records. This information is useful for agriculture, commerce and other purposes. For a more detailed description of seasons, see Thursday's optional Supplemental Information - Meteorological Seasons.
To be submitted on the lines for Thursday on the Study Guide, Part B, Applications', Week 4 Chapter Progress Response Form, under section B. Daily Summary.
From the files of the Aviation Weather Center, Kansas City, MO and Intellicast