In Corpus Christi Bay, we experience relatively small daily tidal variations. We have only one high and one low tide each day (our tides are called "diurnal"). Our daily water level fluctuation is typically only 6 to 12 inches. In contrast, most areas along the east and west coasts of the United States experience semi-diurnal tides, meaning that they have two high and two low tides each day. The total range from a day's higher high tide to its lower low tide is typically larger than ours--in some places 6 to 12 feet. Our tidal currents tend to be relatively small, too.  Since there is only one high tide per day and the total range is usually less than 12 inches, there are few places on Corpus Christi Bay where one can notice any tidal current at all.  One exception is the ship channel near the town of Port Aransas--there the tidal currents are often significant.  But Corpus Christi Bay has one interesting property regarding water levels:  the weather can significantly change the overall water level for several days at a time.  In particular, the cold fronts that tend to come from the northwest accompanied by strong sustained winds over 30 knots tend to "blow the water out of the Bay."  For several days during and after the passage of these fronts our water levels will often be 1-2 feet below the levels predicted by the positions of the moon and sun (the elements of a normal "tide").  During these extreme-low-water periods, boaters must exercise additional caution because water depths can be significantly shallower than marked on nautical charts.  Water that is "normally" six feet deep at low tide can be only four  feet deep, causing a boat to run aground.