Meteorology 302.01, Spring 2004
Class Notes for March 17, 2004

Angela Blank and Glenn Scott

Assignments:

Vasquez: Now in. pp. 1-20 (Introduction; Chapter 1)

Sheets and Williams: Finish the whole book.

Williams (Nothing New)

What You Have Completed So Far
Chapters 1-4 and part of 5; Chapter 9, 148-161

Zebrowski (Nothing New)

What You Have Completed So Far
Chapters 1 and 2; Chapter 3, pp. 53-62; 77-83; 96-101; Chapter 5, pp. 143-145; 157-163 Chapter 8, 229-251

Housekeeping:

v Reviewed today’s surface map

v Reviewed current reading assignments

Surface Weather Map:

v Wave cyclone: a frontal cyclone in which air moving counterclockwise and inward induces a wave like configuration in the frontal pattern.

v Dry line: a boundary between warm dry air and warm moist air.

v Warm front: indicated by red semi-circles pointing away from the warmer air and pointing in the direction towards which the warm air is moving.

v Cold front: a front that moves toward warmer air.

Hurricane Topics:

So far, we have only completed question number one: What is a hurricane?

Answer: A hurricane is an intense tropical cyclone with maximum 1-minute sustained surface wind greater than 64 knots [74 mph]) originating over tropical or subtropical waters. Hurricanes and tropical storms are also associated with organized convection having definite counterclockwise surface wind circulation, often observable in cloud motions and features.

Storm Prediction Center:

We looked at the convective outlook for day one, were there was a slight risk of thunderstorms, and a chief risk of large hail.

Severe Thunderstorm Probabilities:

We looked at the animated loops, which show the annual cycle of severe weather threats through the year.  Each frame shows the climatological probability of the event occurring within 25 miles of any point for that day based on past statistics. Note: the highest probability is only about 2%. This is why the Storms Prediction Center posts “less than 2%, all areas” if they have no Meteorological reason to expect tornadoes that day.

Make Your Own Weather Map:

We plotted the dew point and the day one outlook to anticipate how the weather will evolve.

Isotherms: show temperature

To plot Dew point temperature, click the box labeled as follows:

□ 2mTd

Note: a high dew point means moist air is present.

Note: moist air moves north in the Gulf Stream and the west coast has lower dew points because of the California Current. Also notice that the day 1 outlook—which can be shown by checking the box next to “day 1 outlook (940)”—shows areas of risk being associated with high dew points.

Storm Chasing: Vasquez Quotes

We discussed the meaning of objectivity and subjectivity.

v Objectivity: how scientists relate their study to theories.

v Subjectivity: appreciating the beauty of the study.

Most scientists (like Monteverdi) follow both behaviors because they contribute to one another.

500 MB Chart:

We located the jet stream by finding the fastest winds, or the closest isobars. We then located a trough (an area of low pressure not completely encircled by an isobar. Although there can be more than one jet stream at any given time, the main jet stream is the Polar Jet Stream. The association between close isobars and the high winds of the Jet Stream (also called the “Storm Track”) can be tested by looking at the 500 mb chart for the Eastern Pacific. This chart only shows isobars (not winds), and the isobars closest together would seem to be the jet stream. This is supported by looking at the 16 km satellite loop, which shows clouds moving along the path indicated by the isobars on the 500 mb chart.

Conceptual Divergence 1

We reviewed how cyclones form with rising air and lower air pressures at the surface.