SAN FRANCISCO STATE UNIVERSITY FALL 2004

DEPARTMENT OF GEOSCIENCES

Meteorology 403

Weather Analysis and Forecasting

Credit: 4 units; 2 units lecture, 2 units laboratory

Room/Time: TH 604 TTH 8:10-12:00

Prerequisites: Metr. 402, Metr 301 and/or consent of instructor

Corequisite: Metr 502

Instructor: John P. Monteverdi

Office Hours: MWF 9:00-10:00 a.m.

Daily Class Schedule: 8:10-9:00 Lecture

9:10-10:55 Laboratory

11:00-11:15 Briefing

11:15-Noon Spot Forecasts

Purpose of the Course

All of you have taken (or are taking) coursework which has introduced you to: (1) some of the basic laws which govern atmospheric behavior (Metr 200, 401, 402, 502); (2) the fundamentals of the hydrostatics, thermodynamics and dynamics of the atmosphere (Metr. 201, 402). Most of you have had some exposure to fundamental analysis techniques (Metr 301) and map interpretation (Metr 301) and some have had the opportunity to do some forecasting (Metr 698), although not in a formal manner.

In many respects, the present course can be considered to be an applications course in which all the theoretical knowledge and practical observational and analysis techniques learned previously will be put to the test. However, because Metr 502 is taken concurrently, many of the topics that we will be discussing that are dependent upon what you cover in Metr 502 will be treated twice: once in Metr 502 and, in a different, operational perspective, here in Metr 403.

You will have already noted that the textbooks for Metr 402/403/502 are the same. This is because modern synoptic meteorology is a essentially an application of the principles of dynamic meteorology to the operational environment, one that is dependent upon viewing circulation systems at the scale of maps and charts showing continental and subcontinental size areas (termed "synoptic" and "subsynoptic").

One strength of the program at SFSU is that it is small enough to be adaptable to the student needs which crop up on a semester to semester basis. The instructors, also, have a commitment to the students and try to maximize their flexibility. As you will see, this semester, Dr. Dempsey and I will work Metr 502 and 403 on somewhat parallel tracks until the fundamental material is covered.

Lecture and Lab

To a certain extent, the lecture portion of the course will be run in a graduate school seminar fashion. The readings in the text book and in various journals will be selected not only to amplify and show application of previous principles to the real world" of forecasting but to stimulate discussion. In some cases, discussion material will be relatively controversial (e.g., "is long range forecasting possible?"; "has computer-based technology "over-high-teched" weather forecasting?"; "should hand-analysis be reemphasized?") and relate to the future of the field.

The laboratory session will really be broken into three portions: (1) lab exercises which will provide you with several more analysis techniques with which you need some familiarity; (2) exercises designed to illustrate or substantiate lecture material; (3) exercises which involve use and programming ofthe WGSL; (4) objective and subjective forecasting techniques. In the lab exercises, the philosophy is to LEARN THE CORRECT TECHNIQUES regardless of the immediate result. In other words, here I still will emphasize the ait is better to be wrong for the right reasons than right for the wrong reasons.

Weather Briefings

Each individual will be responsible for two weeks worth of weather briefings. The briefings are expected to be highly-polished presentations tailored to aid the class in its spot forecasts which follow. It is up to the briefer to post maps, color maps, select topics, etc. appropriate for the level of Metr 403 and the needs of the class. He or she will be graded on the polish (presentation and preparation) of the preparation, but also on the meteorological content. I am assuming that you have mastered the material we have discussed continuously from Metr 201, through Metr 301 to now. For example, if you are still having trouble drawing the thickness advection arrows and understanding how they relate to temperature advection and the quasi-geostrophic forcing for vertical motion, you will be graded off on the meteorology part of the briefing. In fact, unless you can make some insightful (meaning, showing synthesis) comments about the weather patterns/systems on the maps you use, you will be graded off. "insightful" means being able to say something beyond "there is vorticity advection here and the vorticity advection here is positive."

Spot Forecasts

In "the real world" where the advancement of scientific knowledge is not given high priority unless there are immediate practical results, the value of a weather forecast is its accuracy and not the validity of the method used to forrnulate it nor the skill of the individual making the forecast. You will find out, however, that there definitely is a relationship. In any case, the last 45 minutes of the class period will be devoted to making forecasts for 5 cities across the United States. The skill with which you forecast will be reflected in your grade for this course. In this portion of the class, you will be expected to integrate the theoretical knowledge you have obtained with your facility at map interpretation and INTUITION to produce a correct forecast. Exact scoring methodology and "rules of the game" will be explained in another handout.

The Relationship of Forecasting to Synoptic Meteorology

The traditional tasks of the weather forecaster used to be collected under the heading SYNOPTIC METEOROLOGY. Today, it is probably more proper to designate this branch of the field OPERATIONAL METEOROLOGY since many practitioners of the field actively integrate processes that operate at many scales in producing an operational weather forecast. You will hear much about this in the course.

Whether you realize it or not, much of what you learned (and will learn, with some exceptions) in Metr. 402/502 is an overview of the principles of dynamic meteorology which govern the synoptic-scale flow. Scaling considerations and observational evidence consistently point out that the flow depicted on conventional weather charts (e.g., 500 mb) is in a state where all terms of the horizontal equation of motion can be neglected on an order of magnitude basis EXCEPT the coriolis and pressure gradient accelerations. This is nearly true at all levels of the atmosphere except at the surface. The word "nearly" in the last sentence raises "red flags" in the minds of many dynamic meteorologists because for most students and operational meteorologists the word is given the same meaning as "always". A good part of this course will be spent bringing you up to speed on the ways that operational meteorologists have of portraying, visualizing and predicting the "real" atmosphere flow, which is definitely not geostrophic (except in restricted areas) and which always has "lots of accelerations" (remember, the geostrophic wind is supposed to be unaccelerated).

Actually, the "quasi-geostrophic" theory to which you will be exposed in this class and Metr. 502, is nothing new and has been around since the 1940's. However, the geostrophic approximation is such an easy one to understand and has been used so extensively in synoptic meteorology as a way to visualize atmospheric flow, that we have lost sight of what actually is going on. The notions of "quasigeostrophic" theory can be traced back to the 1930's, but really came to the fore with Sutcliffe-Petterssen's Development Equation (SPDE) in the 1940's. The SPDE is very similar to two equations you will be looking at in 502 and in this class, the quasi-geostrophic OMEGA and GEOPOTENTIAL TENDENCY equations. All of these equations basically demonstrate the surface development (SPDE), vertical motion fields (OMEGA) and HEIGHT (PRESSURE) TENDENCIES (Geop. Tend. Eq.) are interrelated and that each of these is due to a combination of DYNAMIC and THERMAL mechanisms.

Those of you who took Metr. 302 or 356 know that surface pressure systems can be thought of as being caused either by thermal effects (THERMAL LOWS) or dynamic effects (i.e., divergence aloft not related to surface heating or cooling) (DYNAMIC LOWS) etc. The derivation of these equations allowed teaching meteorologists to create such categories, but, in reality, nature doesn’t strictly compartmentalize pressure systems into these categories. Your understanding of the equations you derive in M502 (and, in this class) will help you see that many effects (leading to pressure system development) are operating simultaneously, and it is human interpretation that allows us to eliminate minor effects “on an order of magnitude basis”. This allows for an easier physical interpretation.

Since quasi-geostrophic theory does in fact explain much that we see in the synoptic-scale atmosphere, the term paper for this course will consist of EVERYONE selecting one of these equations and applying it to an OPERATIONAL CASE STUDY. I would prefer that the OMEGA EQUATION be used for this, since this is what has been appearing in the literature lately. However, you may feel that one of the other equations is more accessible conceptually. This is fine with me. More about the research paper in another handout.

It is important that students begin to think about the paper early in the semester. Thus, maps and/or data for the particular cases you are interested in should be selected early in the semester. A proposal will be due October 16 and the first draft will serve as your term paper assignment for this semester. I will grade and correct (provide suggestions for revision) of the first draft and the final product will be the term paper due in Metr 503.

GRADING PLAN

Exams

Midterms (2) at 10% each (October 12, Nov. 16) 20%

Final (Lecture/Lab) at 20% (Dec. 18, 8:00 - 10:30 am) 20%

Classwork

Briefings 5%

Forecasts 10%

Lab exercises 15%

Homework 5%

Research Paper (Due Last Class Meeting)

Paper 25%

TEXTBOOKS

Required Textbooks: 13 copies

Bluestein, Howard B., 1993: Synoptic-Dynamic Meteorology in Midlatitudes. Vol II. Observations and Theory of Weather Systems. Oxford University Press. 594 pp.

Djuric, Dusan, 1994: Weather Analysis. Prentice-Hall. 304 pp. ISBN 0-13-501149-3

Recommended Textbooks: 6 copies

Chaston,,Peter R., 1997: Weather Maps: How to Read and Interpret all the Basic Weather Charts. Second Edition. Chaston Scientific, Inc.Kearney, MO. ISBN 0-9645172-4-8, 214 pp.

Vasquez, Tim, 2002: Storm Chasing Handbook. Weather Graphics Technologies. 286 pp. ISBN: 0-9706840-3-7

Vasquez, Tim, 2002: Weather Forecasting Handbook. Weather Graphics Technologies. 198 pp. ISBN: 0-9706840-2-9

Vasquez, Tim, 2003: Weather Map Handbook. Weather Graphics Technologies. 167 pp. ISBN: 0-9706840-4-5,