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Weather Forecast

Saros Weather

December, 2017

1st-3rd. Mostly fair west into Mississippi Valley. Unsettled, with some light snow from Maryland and Delaware to New England. Rain from the Gulf Coast north and east to the Carolinas followed by clearing.

4th-7th. Fair, then unsettled Washington and Oregon. Heavy snow from Colorado and the Central Plains (6 to 12 inches). Unsettled for Southern Plains. Also becoming unsettled Mississippi Valley and east; chilly rain for the Southeast. Showers in California and the Southwest.

8th-11th. Cold for Mississippi Valley east; with snow for the Northeast; mixed precipitation for Mid-Atlantic; a chilly rain across the Southeast. Fair and milder for the West and Southwest, then stormy weather sweeps in from the Pacific, with rain as far east as Texas, and heavy snow (8 to 12 inches) for Utah, Colorado, and the Plains.

12th-15th. Snow for Great Lakes and Northeast, as far south as Maryland and Virginia, followed by fair and cold weather. Showery, thundery for Louisiana and Arkansas area and most of Southeast, then fair. 16th-19th. Mostly fair west into Mississippi Valley, then unsettled, with showers for the Pacific States, light snow over the Rockies to Great Lakes, as well as Nevada east to Texas. Unsettled for Atlantic Seaboard.

20th-23rd. Light snow from Pennsylvania, New York to Maine, then fair and very cold. Fair and very cold from the Far West into the Plains States. Showery across Louisiana and Mississippi through the Southeast, followed by clearing and very cold weather; frosts down to Florida.

24th-27th. Dreaming of a White Christmas? If you live east of the Mississippi, keep dreaming! Turning unseasonably mild with showery rain as a storm takes a track well inland. Showers of rain and/or wet snow for Great Lakes, Ohio Valley, and Midwest. Stormy Christmastime over the West Coast. Heavy snows over parts of the Southwest, the Rockies and through the Plains. Heavy rain in Texas to the Mississippi Valley. Showery for the South.

28th-31st. Stormy in the Northeast, with sleet and snow, then fair and cold. Rain from Florida north through the Mid-Atlantic States, then fair and colder. Mostly fair for West and Mississippi Valley.

High/Low Temperature of the Day

The highest temperature of the day will be about 4:00 p.m., not at 12:00 noon as you might think.

The lowest temperature of the day will occur about sunrise, not at midnight as you might think.

Weather Definitions

Advection Horizontal movement of moisture, fog, etc.
Air Mass A large body of air in which the horizontal difference in temperature and moisture is quite small. Usually used in reference to large high-pressure areas.
Angels Usually used to identify radar echoes occurring in clear air or radar echoes of unknown origin that are not associated with precipitation. Also known as ghosts.
Anticyclone High pressure area. Winds flow clockwise (Northern Hemisphere) and away from center. Air is descending near the center.
Below Minimums In aviation when the clouds above ground level are 1,000 feet or less and/or the visibility is 3 miles or less. Requires instrument flight rules.
Celsius A temperature scale. C = 5/9 (F-32).
Clear Skies Less than 1/10 of the sky is covered by clouds.
Cloud A visible mass of very small water or ice particles.
Cold Front A zone where cold air is replacing warm air.
Collar Cloud A cyclonically rotating band of clouds which suggests the possibility of a tornado or that band of clouds rotating around the tornado where it comes out of the base of the thunderstorm.
Convection Usually means vertical movement of air upward due to heating from the sun.
Convergence Where the horizontal wind flow into a certain region is greater than the outflow. Usually results in rising air when occurring along the surface of the earth.
Cyclone Low pressure area. Wind flows counterclockwise (Northern Hemisphere) and toward the center of the low and rises near the center.
Dew point The temperature to which air must be cooled (pressure and moisture remaining constant) to cause clouds or fog to form.
Divergence Where the horizontal wind flow out of a certain region is greater than in inflow. Usually associated with areas of high pressure.
Dry Line The zone between one very dry air mass and another very moist air mass. On occasion, thunderstorms become very active on the east side of the dry line.
Exosphere The very outer limits of our atmosphere. Not believed to be of meteorological significance.
Fahrenheit A temperature scale. F = 9/5 C + 32. (32 F = 0 C.)
Fair Skies Less than four tenths of the sky is covered with clouds of the low type. Implies good weather.
Fall Equinox
Autumn Begins
Occurs near September 22 and marks the beginning of fall and the end of summer. Sun’s rays are perpendicular to the equator.
Fine Line A radar echo that appears as a fairly long thin line and is not associated with precipitation. It apparently is caused by an abrupt temperature and/or humidity change in the air and quite often signals the approaching wind shift of a front or winds from a line of thunderstorms.
Fog A cloud with its base on or near the surface of the earth.
Frontal System Used to describe the cold, warm and/or stationary fronts associated with the same storm system or low pressure area.
Frontogenesis The formation of a front.
Frontolysis The dissipation of a front.
Frost Moisture that freezes on surfaces usually in clear, stable air and light winds.
Funnel Cloud A tornado not touching the ground.
High Pressure Area Anticyclone. Winds flow clockwise away from the center. A region of stable and descending air.
IFR Instrument flight rules. When clouds above ground level are 1,000 feet or less and/or the visibility is 3 miles or less.
Increasing Cloudiness Used when the amount of the sky covered with clouds is expected to be greater than at the present time. Often used to suggest the approach of stormy weather.
Inversion Where the temperature increased as you go up in atmosphere (rather than decreases, as is expected normally).
Isobar A line connecting points of equal pressure. The closer these lines, usually the stronger the winds.
Isotherm A line connecting points of equal temperature.
Jet Stream A band of winds in the upper atmosphere of 50 knots or greater…average jet winds are about 100 to 150 knots with an average length of 1,000 to 3,000 miles, and 3,000 to 7,000 feet in depth. The average height of the jet stream above ground level in the mid-latitudes is approximately 35,000 feet. One knot = 1.15 mph.
Low Pressure Cyclone. Winds flow counterclockwise (Northern Hemisphere) and toward the center of the low system and then rise near the center.
Mesosphere A region of our atmosphere which extends from about 32 to 50 miles above the earth’s surface. Is marked by decreasing temperatures.
Norther Usually describes a fast moving cold front, which brings much colder temperatures and strong northerly winds.
Overcast Used to describe the sky condition when 95% or more is covered with clouds.
Overrunning When warm and usually moist air is going up over the colder and more dense air of a cold air mass.
Partly Cloudy When four tenths to seven tenths of the sky is covered with clouds.
Precipitation Moisture that is falling from a cloud in liquid or solid form. Rain, sleet, snow, hail, etc.
Pressure The weight of the air above a given location from the surface of the earth to the top of the atmosphere.
Pressure Gradient Horizontal change in pressure. The larger the change, the tighter the gradient and usually the stronger the winds.
Relative Humidity The amount of moisture (water vapor) in the air relative to the maximum amount it can hold.
Ridge As elongated area of high atmospheric pressure.
Roll Cloud Low clouds associated with an approaching thunderstorm, which appear in a low rolling band.
Short Wave Minor. Usually refers to a small disturbance near the 18,000 foot level which is capable of producing weather.
Spring equinox
Spring begins
Occurs near March 21 with the sun’s rays perpendicular to the equator. Marks the beginning of spring and the end of winter.
Squall Line A line of active thunderstorms.
Stable Air Air which resists upward movement and is usually free of precipitation.
Stationary Front A front that is not moving.
Stratosphere That layer of air extending from approximately 7 miles to 32 miles above the surface of the earth. Is marked by a slight temperature increase.
Summer Solstice
Summer begins
Occurs near June 21 with the sun’s plane striking the earth at 23-1/2 north latitude. Marks the beginning of summer and the end of spring.
Temperature May be regarded as the degree of hotness or coldness or as a measure of heat intensity.
Thermosphere That layer of air extending from about 150 miles above the earth’s surface to the outer limits of atmosphere.
Troposphere That layer of air extending from the earth’s surface to approximately 7 miles. Most of our weather occurs in this layer.
Trough An elongated area of low atmospheric pressure. Sometimes will produce weather of various types.
Unstable Air Air which can be displaced upward easily and is capable of producing clouds and precipitation.
Variable Cloudiness Describes the condition of the sky when it is expected there will be varying amounts of cloud cover. In other words, sometimes cloudy and sometimes partly cloudy, all during a certain forecast period.
VFR Visual flight rules. When the clouds above ground level are greater than 1,000 feet and the visibility is greater than 3 miles.
Virga Precipitation that is falling from a cloud, but is evaporating before it hits the ground.
Warm Front A zone where warm air is replacing cold air.
Wind Direction Direction from which the wind is blowing.
Winter Solstice
Winter begins
Occurs near December 22 with the sun’s plane striking the earth at 23-1/2 degrees south latitude. Marks the end of fall and the beginning of winter.