June 25, 2009 Meeting Summary
Mark DeMaria presented a few slides on intensity model performance during Hurricane Andres in June 2009. Mark mentioned that Andres was classified as a hurricane most likely due to aircraft reconnaissance. The storm's short lifetime and rapid demise could be due to its track very near but not over land and a gradient in thermodynamic stability. In slides 3 and 4, the blue line represents the best track while red lines are model forecasts. For the maximum wind intensity shown in slide 3, the HWRF over-intensified Andres, however it did capture the storm's rapid weakening. Mark mentioned that 30 degree Celsius SST values used for the first 48h HWRF forecasts probably attributed to the model's over-intensification of Andres. The HWRF track also kept Andres further to the left of the GFDL track and over the ocean. Meanwhile, the GFDL model, which uses a spun-up vortex, never intensified Andres very much. This is consistent with GFDL's track for Andres showing the storm moving in a more N/NW direction over land. Slide 4 shows the maximum wind intensity for statistical models Decay-SHIPS and LGEM. Both statistical models under-forecast the rapid weakening of Andres. Mark reasoned that this could be due to a layer of marine stratocumulus clouds shown on satellite pictures that moved into the storm from the west which the models failed to detect. Overall, the model consensus on Andres was deemed "good", and Mark mentioned that it appeared the models performed well with the thermodynamic variations, especially for the first named storm.