Case 035: San Antonio Flood Lab Exercise
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Case 035: San Antonio Flood Lab Exercise |
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Learning Objectives
(1) To recognize the important considerations for issuing QPFs for a significant event.
(2) To get a feel for some of the unique aspects of a particular event, especially the initiation and regeneration mechanisms.
(3) To recognize the difference between a significant precipitation event and one that is truly historic.
Materials Provided
(1) Quick hand analyses of surface pressure (every 2 mb) and dewpoint (every 2°F) for 0600 UTC 17 Oct, and surface theta-e (every 2K) for 0600 17 Oct.
(2) 250 mb isotachs, 850 mb plots & dewpoints analyzed at 0000 UTC.
(3) ETA 6-h and 24-h forecasts valid at 0600 17 Oct and 0000 18 Oct for 925 mb theta-e & wind, and precipitable water.
(4) Corpus Christi 0000 UTC sounding.
(5) HPC Day 1 QPF for 24-h period ending 1200 UTC 18 Oct.
(6) TX maps with counties, and WSR-88D locations, and topography.
Assignment Part I (~1h) SET AWIPS CLOCK TO 0615 17 Oct 1998
You may review any data through 0615 UTC 17 October, including any forecast periods from numerical models issued at or prior to 0600 UTC (Meso-ETA at 0300, and RUC at 0600). Do not look at observational data beyond 0615 UTC.
Where and when will the strongest sustained (>50 dBZ) convection initiate? Mark an “X” or a short line where the initiation will be, and write the time (in UTC) on the map provided.
Look at the HPC and model guidance for a QPF for the 24h period ending 1200 UTC 18 October. Alter this if necessary and draw a 3-inch isohyet if you believe there will be that much. If you think there will be more, draw isohyets in 2 inch increments beyond 3 inches.
Assignment Part II (~30 min)
Set clock to 1715 UTC 17 October.
Do a quick hand analysis of surface features with the surface plot for 1700 UTC.
Where will the heaviest rainfall be in the 6-h period ending 0000 UTC 18 October? What might be the greatest point amount? Outline this area on the map and write in the maximum point value.
Which areas should be in a flash flood warning at this time? Any severe weather threat?
Set clock to 2315 UTC 17 October.
Do a quick hand analysis of surface features with the surface plot for 2300 UTC.
Where will the heaviest rainfall be in the 6-h period ending 0600 UTC 18 October? What might be the greatest point amount? Outline this area on the map and write in the maximum point value.
Which areas should be in a flash flood warning at this time? Any severe weather threat?
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