Coastally Trapped Wind Reversals

Coastally Trapped Wind Reversals
At the end of the module you should be able to do the following things: With regard to characteristics of CTWRs • Describe how pressure, temperature, and wind change with passage of a coastally trapped wind reversal (CTWR) • Recall how quickly CTWRs propagate up the U.S. West Coast • Recall why SLP rises after passage of a CTWR • Locate areas likely to experience CTWRs on a physical map of the world • Recall the frequency of CTWRs along the California coast • Explain why CTWRs are best explained as a Kelvin wave, rather than a gravity wave With regard to the structure of CTWRs • Describe how the MBL changes with passage of a CTWR • Recognize how a cross-coast profile of the MBL changes during a CTWR • Recognize a CTWR on a wind profiler record • Recall the height at which wind first reverses direction as a CTWR propagates • Recall the association of stratus formation with CTWRs With regard to the synoptic evolution of CTWRs • Describe how MSLP, 850-mb heights, and 500-mb heights depart from climatologic norms during a CTWR • Describe how changes in MSLP and 850-mb pressure force low-level offshore winds, and how this affects sensible weather along the coast • Describe how variations in MSLP affect along-shore pressure gradients With regard to the mesoscale evolution of CTWRs • Recall how the synoptic setup forces the mesoscale offshore low • Recall how the offshore low moves during a CTWR • Describe how coastal mountains force ageostrophic flow • Recall how coastal mountains contribute to warming of offshore winds • Describe how and why a mesoscale high forms along the coast • Recall the factors that cause northward propagation of the CTWR With regard to forecasting CTWRs • Recall the 3 best synoptic clues for forecasting a CTWR • Recall where the offshore low forms with respect to the low-level offshore flow • Recall where the stratus surge initiates with respect to the offshore low • Describe the use and limitations of mesoscale NWP models in predicting CTWRs