The lowest sea level pressure ever observed for a hurricane in the Western hemisphere: 879 hPa (millibars). The absolute lowest pressure anywhere was 870 hPa in Typhoon Tip in 1979 over the western Pacific. We are talking about bringing the normal pressure at 5000 ft down to sea level----amazing.
The sustained winds reach 200 mph, with gusts substantially higher This greatly exceeds the criteria for a Category 5 storm (sustained winds equal or greater than 156 mph).
The storm developed faster than any other Western Hemisphere storm on record, going from a a tropical disturbance to a category 5 storm in less than 24 h. We are talking about a 100 hPa pressure decline in less than a day. Unbelievable.
The eye of Patricia was quite small (about 8 miles) at landfall yesterday, something obvious in the satellite picture shown above.
Why did Patricia rev up so quickly? I don't think we understand the origins of the extreme behavior, but the conditions were ideal: very warm ocean temperatures, deep warm water, low wind shear in the vertical, unstable conditions. In fact, the waters off Mexico are now some of the warmest on the planet (see image) and a big reason for that is the major El Nino that is occurring currently.
Forecast Problems
Patricia is a poster child, perhaps the worst case in a while, of a major problem for meteorologists: we have gained substantial skill in forecasting hurricane tracks, but we often fail in predicting hurricane intensification.
Let's be honest here: NONE of our numerical prediction models, or our statistical aids, predicted the extreme intensification of Patricia.
Consider the National Weather Service's primo modeling system for hurricane forecasting (HWRF), something they have invested tens of millions in. Here is the HWRF forecast available late Wednesday. HWRF forecast (purple lines) lowest pressure only declines to 950 hPa and sustained winds reach 95 knots (109 mph). Not good--they are predicting a storm that is half as intense as reality.
The forecasts the day before improved substantially--but that left little time for preparation. Here is the forecast available about 12h prior to landfall.
In contrast to intensification forecasts, the track forecasts were skillful and stable for days before. Why the difference? To forecast track one does not have to predict the complex inner dynamics of the hurricane; if you can skillfully predict the general environment (the steering flow), you can get the track correct. And our large scale models (like the NOAA GFS and the European model) can generally do that.
But predicting intensity is a very different thing. You need to know the inner structure of the storm and predict its evolution. The size and evolution of the changing eyewall clouds, the development and contraction of new eyewalls, and much more. This is very hard in many ways. Some research suggests that it may not be even possible to do this more than a day or two out. An area of active research.
Texas flooding
Patricia, although radically weakened by its passage over land (robbing it of moisture) and terrain (which tears the lower structure apart), is not done causing problem. The residual circulation and moisture of the storm will meet up with an approaching upper level disturbance over the southwest U.S, and moisture from off the Gulf of Mexico. to produce extreme precipitation over southern Texas. Here is the predicted precipitation total for the next 48h from the National Weather Service GFS model: 10-15 inches over coastal Texas. Serious trouble and the potential for flash flooding.
The National Weather Service forecast for Houston says it all:
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