October 19, 2010
Well, the models have been all over the place over the past few runs with what they are showing, and I know exactly why. First, the jet stream is very strong, and although models are good at picking up this pattern, they have a hard time pinning down what storms will affect which areas at which time. Often, when the models are as inconsistent as they are now, meteorologists will “broadbrush” the forecast, meaning they say it will be wet but don’t give any specific details. Usually it is reserved for longer range forecasts outside of a week or so, and this storm is expected to come in Saturday night. However, due to the inconsistencies in the models, the NWS guys are just saying it is gonna be wet and giving more details later. Another reason is that the NWS confirmed that tropical moisture IS going to be entrained in this system (I called it!) from supertyphoon Megi, which once had a central pressure of 895 millibars and sustained winds of 180 miles per hour! Obviously, that powerful of a storm is going to offer some very deep tropical moisture, and just how much of it gets entrained in the jet stream is going to make a huge difference on what kind of a storm we will see. Our models generally have issues pinning down details when tropical moisture is involved.
The trend over the last few model runs has been to put the heaviest precipitation in California. We will see if this comes true. Washington will still get a good soaking though, and there could be very strong winds out on the coast and at least blustery winds inland. Here’s the 24 hour precip ending at 5 P.M. Sunday. Lots of 10+ inch totals in the mountains of Northern California.