WELCOME BACK: Procedure continued from STUDY GUIDE.
During the weekend a tropical weather system formed in the Gulf of Mexico, grew to become a minimal hurricane, and then weakened as it struck Florida in the panhandle. Hurricane Gordon was spawned over the warm waters of the Gulf and weakened as it crossed cooler near-shore waters and then rapidly declined as the friction over land slowed its near-surface winds to tropical storm force. Meanwhile most of the eastern portion of the country enjoyed pleasant fair weather due to high pressure. The West also remained relatively dry but warm.
The electronically delivered weather maps used in this course typically have greater detail than those seen on television or in newspapers. The Sunday 12Z 17 SEP 2000 (6 AM CDT) surface map (Image 1, Isobars, Fronts, Radar, & Data), depicts weather conditions across the country at that time. At this time Hurricane Gordon was located in the Gulf of Mexico southwest of Florida. A frontal system stretched from south of Texas across Florida into the Atlantic Ocean. The section of front shown with triangles (blue on screen) from Texas into the Gulf is given as a [(cold) (warm) (stationary)] front. From the Gulf into the Atlantic, the front is shown with alternating (blue) triangles and (red) semicircles on opposite sides. This section would be a [(cold) (warm) (stationary)] front.
Another frontal system stretches from a low-pressure center of 995 mb in east central Canada to another Low in eastern Montana. This system is shown as composed of occluded, cold, and stationary frontal sections. The large high pressure area that brought pleasant weather to the eastern portion of the country is between these two frontal systems. With the approach of Hurricane Gordon, southern Florida was under two tornado watches as shown by areas within the (red on screen) boxes. The watches, #T740 and T741, as consecutively numbered through the year, were issued by the National Weather Service's Storm Prediction Center.
At map time, Little Rock, Arkansas, under the influence of high pressure, had a temperature of 53 degrees F, and a dewpoint of [(46) (53)] degrees F. The winds were generally [(from the north at 10 knots) (calm)], and the air pressure corrected to sea level was [(1214.0) (1021.4)] mb. The sky was [(clear) (overcast)].
Tampa, Florida, with a temperature of 70 degrees F and dewpoint 69, was overcast with 10 knots winds from the east. Two dots to the 9 o'clock position of the station model indicate the reported current weather conditions. Two dots is the symbol for continuous [(snow) (rain)]. These conditions were associated with Hurricane Gordon. [For symbols, see the Homepage User's Guide.]
San Diego, California has two horizontal lines in the current weather position of its station model. These lines represent [(snow) (fog)]. The temperature is 66 degrees and the dewpoint is _____ °F. This equality means the air at San Diego was saturated.
Image 2 is the surface map for 00Z Monday 18 SEP 2000, 12 hours later than the Image 1 map. Gordon is now about onshore along the Florida Gulf coast. Tornado watch # 742 was in effect for most of Florida. Winds at Tampa were [(east at 10) (southwest at 25)] knots. Miami was reporting 2-dot rain (also seen by a national television audience at their football game) while Tallahassee had 3-dot rain (heavy).
temperature: | [(43) (76)] | °F |
dewpoint: | [(43) (76)] | °F |
pressure: | [(1175) (1017.5)] | mb |
wind: | [(calm) (east at 1 - 2 kts)] | |
sky condition: | [(clear) (overcast)] |
Current weather symbols (9 o'clock position of the station model) for
the following stations were:
San Diego, California ("8" on side) _______________________
Los Angeles, CA (broken line over solid line) _______________________
Ottawa, Canada (dot over triangle) _______________________
The cold front in the northern US had moved across Lakes Michigan and Huron during the interval from 12Z on the 17th to 00Z on the 18th. This direction was generally toward the [(northwest) (southeast)]. The stationary section of the front had not moved much.
The section of the frontal system in the southeast from northern Florida into the Atlantic was shown at 00Z as a [(cold) (warm) (stationary)] front. This section at 00Z was located further to the [(north) (south)] than that frontal portion had been at 12Z. The section from Florida westward into the Gulf of Mexico was shown as a cold front on the 00Z map indicating that at map time cooler air was heading south behind the circulation of Gordon.
Displaying a sequence of recent surface weather maps ending with the current map in your classroom can show the movement of "weather makers" (high and low pressure centers and fronts) and the changes in atmospheric conditions at your location over time resulting from their movements. Practice looking for connections between weather changes depicted on the map sequence and predict local weather for the next half day or so.
The National Weather Service provides information of current weather conditions especially highlighting threatening and/or severe weather, via their http://iwin.nws.noaa.gov/iwin/iwdspg1.html page. Choosing a state will show the weather reporting sites in that state, which may be useful to locate the stations, as well as obtain the current observations and forecast conditions. You may wish to note or "bookmark/favorite places" this site for future reference.
Hold this activity until you have completed all applications for this week. Instructions for faxing your LIT mentor will appear at the end of this week's Activity B.
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