ATS/ESS 452: Synoptic Meteorology Friday 22 Aug 2014

1. ATS/ESS 452: Synoptic Meteorology Friday 22 Aug 2014 • Finish Overview Presentation • Current Weather Discussion • Begin Review Material

2. GOES-12 IR satellite image of Hurricane Bill at 0615 UTC 19 August 2009 GOES-12 IR satellite image, 0615 UTC 19 August 2009

3. 06 UTC GFS sea-level pressure (SLP) analysis for Hurricane Bill GOES-12 IR satellite image, 0615 UTC 19 August 2009

4. Hurricane Bill was forecasted (correctly) to curve harmlessly out to sea. But WHY did this happen?

5. GFS 60-h SLP + 500 mb forecast, valid 18Z Aug 21, 2009 What do you see that may be important to Bill’s forecast? 500 mb trough

6. GFS 84-h SLP + 500 mb forecast, valid 18Z Aug 22, 2009 Notice the interaction between the trough and Hurricane Bill. The upper-level winds associated with the trough will “push” Bill out to sea.

7. How can we trust the previous GFS forecast for the trough interaction with Bill? • Model initiation errors? • Did the model initiate Bill at 980mb when it’s really 950mb?  Why is this important? • Forecast consistency • Many other models… what do they say? • Ensemble forecasting • Known model bias

8. A little more disagreement between model ensemble members.

9. Today’s Numerical Weather Models Are Pretty Good… Are Humans Still Needed? • Yes!! But roles are changing • Need to improve risk communication (e.g. April 27 outbreak), predictability and uncertainty in forecasting • Skill in augmenting the numerical forecast; local complexities which models often have difficulty in understanding • Demand is increasing for understanding and applying new technology • Still LOTS of research questions remain

10. Start To Get Familiar With… MOS NCEP Model Guidance Another Good Model Site – TwisterData Another Good Model Site – Earl’s Current Weather Page Read NWS Area Forecast Discussions – HUN Example Read SPC Products HPC Sfc Products and Discussions

11. Current Weather Discussion

12. Begin Review MaterialReading Assignment:pp. 1 – 11 from Lackmann

13. Scales of Motion Jet Stream, Trade Winds, Longwave pattern Shortwaves, Fronts, Jet Streaks Thunderstorms, Sea Breezes Turbulence, Boundary Layer Phenomena This information is important for simplifying the equations that describe our atmosphere through a process known as scale analysis **Determine which physical processes are most important and which can you neglect.

14. Variables, Coordinates, & Units • Cartesian coordinate system (x, y, z) is the most typical coordinate system used in meteorology • x: zonal (East-West) direction; positive towards the east • y: meridional(North-South) direction; positive to the north • z: vertical (up-dpwn) direction; positive upward • What other coordinate system do you think we will use? • - Pressure coordinates

15. Variables, Coordinates, & Units Wind velocity are based on the time rate of change in the distance along its respective coordinate axes following the airflow zonal wind: meridional wind: vertical wind: **start to refer to directions using these names The Coriolis parameter (f) is related to the spin of the Earth and is given by: where φ is the latitude and Ωis the rate of Earth’s rotation (7.292 x 10-5 rad s-1)