Wednesday, September 15, 2010

Autumn Is Knocking On The Door.

Chance of rain by the end of this week. The Aleutian storm corridor is opening. Cool weather to filter in early next week. Monday afternoon was warm, sunny and windless. Sure seems like Autumn. Welcome.

Some of you may have noticed a bit of rain last Wednesday. It was brief and sporadic, but definitely it was rain, and not what some of us coastal dwellers call 'heavy fog." We had a large weak low pressure system sitting on top of us for a day or so. It also had cooler temperatures associated with it. Since then, we have seen a warming trend and very fall like weather. Cool crisp mornings, followed by sunny, warm and windless afternoons. Lovely.

This week we have a perisitant large weak low pressure system sitting just off shore. Our weather to remain calm through the end of the week. Over this coming weekend, that low pressure system is to tighten up a bit and slowly edge on shore. The bulk of this system should effect Mendocino and northward, with heavy rains possible in the coastal mountains. Chance of rain in the Bay Area, increasing as you move north. Greatest chance of rain is late Sunday and into Monday morning. If you have an outside project going, you may want to watch the weather closely as the weekend approaches - and be ready to get a cover out there.

As this system moves over us, we can expect cool air to filter in behind it. Of more interest is the fact that the large summer time high pressure system that usually sits to our West, is not expected to bounce back. Instead, a series of low pressure systems are likely to begin queuing in the north Pacific. Most of these are foretasted to stay north of the Bay Area, but there is a chance of rain and storminess every 3-5 days for the next few weeks. When we look on the fantasy models, there is a large strong system foretasted to brush us about two weeks out. Will need to watch this one.

What does this mean for our gardens? This weekend's weather should not bring much rain with it. Hopefully this means we do not need to worry much about the loss of dry farmed tomatoes. Remember, the first big rain can cause these fruits to burst, or worse, for the plants to die. The temperature drop may be more significant, but we are not expect wintry cold, just a cool down. OTOH, for you coastal folks, this system may wipe out the marine layer, which would result in longer sunnier periods.

Regardless, it should be interesting. The shift in the models recently suggests that summer is over, and we are making a swift shift towards winter. Time will tell.

In other news, Igor is churning up the Atlantic. If you have friends or interests in Bermuda, you may want to keep your eye on this system. If you are interested in surfing Timber Island, book your flight for tomorrow to Portland. This may be one for the history books.