A weather map is an important tool for geographers. A succession of three or four maps presents continuous picture of weather changes. Weather forecasters are able to determine the speed of air masses and fronts (冷暖空气团接触的锋) to determine whether an individual pressure area is deepening or becoming shallow and whether a front is increasing or decreasing in intensity. They are also able to determine whether an air mass is retaining its original characteristics or taking on those of the surface over which it is moving. Thus, a most significant function of the map is to reveal a summary picture of conditions in the atmosphere at a given time.

All students of geography should be able to interpret a weather map accurately. Weather maps contain an enormous amount of information about weather conditions existing at the time of observation over a large geographical area. They reveal in a few minutes what otherwise would take hours to describe. The United States Weather Bureau issues information about approaching storms, floods, frosts and all climatic conditions in general. Twice a month it issues a 30-day “outlook” which is a rough guide to weather conditions likely to occur over broad areas of the United States. These 30-day outlooks are based upon an analysis of the upper air levels which often set the stage for development of air masses, fronts and storms.

Considerable effort is being exerted today to achieve more accurate weather predictions. With the use of electronic instruments and satellites, enormous gains have taken place recently in identifying and tracking storms over regions which have but few meteorological stations (气象站). Experiments are also in progress for weather modification (改变) studies. But the limitations of weather modification have prevented meteorological results except in the seeding of super-cooled, upslope mountainous winds which have produced additional orographic (山岳形态) precipitation on the windward side of mountain ranges. Nevertheless, they have provided a clearer understanding of the fundamentals of weather elements.

On the day the tornado(龙卷风) hit, there was no sign fierce weather was on its way— the sky was blue and the sun had been out. The first warning my husband, Jimmy, 67, and I, 65, got came around 9 p.m., from some text on the TV Jimmy was watching. He ran upstairs to find me in our third-floor bedroom, and we changed the channel from the national television to our local Pensacola, Florida, station.

Soon the tornado was on top of us. It was the loudest thing I have ever heard. The bones of the house shook, and the power went out. And the wind began to roar(咆哮) through the house, most likely through blown-out windows and the door to our garage. Everything was moving. And the back wall of the house came off and flew into the darkness outside. We had three flights of steps to get to the storeroom down there, the relative safety of the first floor.

I didn’t know how or if we would make it down the steps. It felt as if there were no floor underneath me as the wind lifted me off my feet. As we finally reached the last flight of steps, our front door blew out. Suddenly, a three-foot-long tree branch flew over our heads, missing us by inches.

By the time I reached the storeroom, the tornado had been over us for about a minute. Jimmy pushed me down to the storeroom floor, but he couldn’t get inside himself because of the wind. I held Jimmy’s arm as the tornado blew the door open. My knees were full of glass, but I felt no pain. If I had let go, Jimmy would have flown right out the back of the house.

All of a sudden, Jimmy lifted off his feet. I thought he was gone. And then everything stopped. He landed on his feet. In those first quiet moments, I couldn’t believe it was over. Our neighbor says the storm lasted four minutes. In that time, four of the twelve town houses in our unit were completely destroyed. Amazingly, none of us were seriously injured.

Today:

A chilly (寒冷的) and frosty start for many this morning, followed by a day of sunshine and local showers. The showers will be slow moving and heavy at times, particularly in the east with a risk of thunder.

Tonight:

Showers will ease this evening and clear spells (一段时间) will develop causing a widespread frost. However, rain will push into the northwest during the early hours, turning heavy at times.

Friday:

Rain, locally heavy, will continue southeastwards through the day with strong winds. Elsewhere, it’ll be bright with some sunshine.

Outlook for Saturday to Monday:

Rain across central parts on Saturday will ease and move northwards. Largely dry elsewhere with some misty sunshine. Mixture of sunshine and showers on Sunday and Monday, turning warmer.

Updated at: 0404 on Thu 31 Mar

UK 6-30 days

UK outlook for Tuesday 5 Apr to Wednesday 13 Apr:

A generally unsettled picture is likely next week, with showers or longer spells of rain affecting the majority of the UK, but with some drier and sunnier interludes (间歇). Temperatures will probably be around normal for most, but central and southeastern areas may see some warmer air moving up from the continent at times. The week after next will probably continue to be changeable with showers or longer spells of rain crossing the UK, but with some brighter and drier interludes in between. Temperatures may become rather low across the north and northwest later next week.

Updated at: 1236 on Wed 30 Mar

UK outlook for Thursday 14 Apr to Saturday 30 Apr:

It is likely to be changeable with a mixture of sunny spells and showers. However, some longer drier spells are also likely, particularly in northwestern areas. Overall temperatures will remain around normal for the time of year but with some warmer spells developing at times.

Updated at: 1237 on Wed 30 Mar