September 2008

September 30, 2008
Predicted: 75 51
Actual: 71 52

It’s late so not much of a post today, but I do want to mention that tomorrow may be your last 70 + day till spring and that the storm slated for Friday-Saturday is looking nice and juicy. It is, after all, forming out of the remnants of a category 4 typhoon.

Wednesday: 75 56 partly cloudy (only doing one day becuase it’s late and the forecast hasn’t changed much

Extended: Models are going wacko but we should expect typical late fall/early winter weather, so it should be relatively wet and cool with some dry periods
September 29, 2008
Predicted: 74 51
Actual: 75 50

Yikes! It’s been a while since I have written. I have been nowhere near a computer for the past three days, but it’s not like anything major has happened over those days, so it isn’t to big of a deal. Today was nice, bright, warm, and sunny as high pressure coupled with weak low pressure off of our coast caused us to heat up. The high pressure would have kept us sunny and warm, but the low pressure, believe it or not, made it even warmer. In the atmosphere, wind works because the atmosphere is always trying to even itself out; higher pressure flows to lower pressure, and this creates wind. When you have low pressure off the coast, wind from inland Washington rushes down to fill in the low pressure. While low pressure usually means rain, this low was very weak and didn’t generate that. Instead, it generated this offshore flow. When this happens, air going to the low pressure system comes off of the Cascades and is warmed, dried, and compressed as it sinks in elevation. This is called adiabatic warming. When the air gets to us, it is significantly warmer and drier than it was just a couple thousand feet above us. Anyways, yesterday was probably the nicest day you will see for a while. By the end of this week, fall will be in full swing, with rain and breezy conditions.

Forecast:
Tuesday: 75 51 partly sunny
Wednesday: 75 52 partly cloudy
Thursday: 67 53 showers developing
Friday: 60 50 rain
Saturday: 61 49 showers

Extended: The jet stream may split later on which would direct systems to our north and south but this remains to be seen. Either way, we will have rainy periods intermixed with sunny ones.

September 25, 2008
Predicted: 61 49
Actual: 62 53

Some good news for you all! Saturday, which was looking a little iffy on the sunshine, is now expected to be a little better. We were even looking at some drizzle and while that threat hasn’t completely gone away, it has fizzled somewhat, just like the front expected to come in. It will provide some clouds though. I am by no means forecasting bluebird skies.

Forecast:
Friday: 66 51 mostly sunny
Saturday: 68 50 partly cloudy
Sunday: 72 50 partly cloudy
Monday: 74 51 mostly sunny
Tuesday: 73 50 partly cloudy

Extended:
Expect our first prolonged period of rain and unsettled weather to begin late next week!

September 24, 2008
Predicted: 62 50
Actual: 59 50

We got a little bit of rain today and a little bit of wind along with that. No major changes in the forecast but Saturday, which was originally planned to be sunny, could have some spotty drizzle as a weak weather system may sqeak by the ridge. We will see what happens! Later next week, after our sun, looks wet and possibly stormy.
On rainshadowing, when air rises it cools, condenses, and expands. When air sinks it warms, dries, and shrinks. So where air is rising and condensing on one side of a mountain range (ex: Olympics), it is warming and drying on the other side (Sequim)

Forecast:
Thursday: 61 49 few am showers
Friday: 65 50 partly cloudy
Saturday: 64 51 mostly cloudy
Sunday: 70 51 mostly sunny
Monday: 70 49 mostly sunny
Monday:

Extended:
The sunny period is no longer in the extended. Anticiplate a return to unsettled weather next week.

Forecast:

September 23, 2008
Predicted: 64 50
Actual: 61 43

The system pegged to come in late tonight is looking slower and weaker, so rain is now pegged to arrive on the coast at about midnight or early morning, spreading inland by late morning Wednesday. Rain totals are expected to be around a tenth of an inch regionwide, but with the winds aloft, expect there to be an inch or greater of rain in the mountains, especially the SW facing slopes of the Olympics. Sequim will be rainshadowed because of this, and they should be dry (more on rainshadowing tomorrow)

Forecast:
Wednesday: 62 50 rain
Thursday: 60 49 morning showers
Friday: 66 50 mostly cloudy
Saturday: 67 50 partly sunny
Sunday: 72 51 sunny

Extended:
There is a little bit of uncertainty in the extended but it looks like the ridge over the weekend will kind of hold in place for a little while, bringing us some nice weather with a little rain later next week.

September 22, 2008
Predicted: 62 52
Actual: 63 49

The transition from summer to fall is often pretty abrupt. We are used to blazing sunshine and heat waves at Bumbershoot, but by the time halloween rolls around, we are often dealing with flooding, windstorms, and heavy mountain snow. I usually like to call the period we are in right now “the grey zone.” We are on the edge; we slip in and out of periods of weather rather than stay in a long pattern. We get a taste of what to come but we remember the smells and sights of summer as well. Tomorrow night into Wednesday, we will get our first shot at a real storm. It is pretty weak, but I would definately count it as the first organized system of the 2008-2009 fall/winter/spring stormy season. It will bring some rain with some breezy conditions. It is not a strong storm by any means, but it will be the strongest one we have had so far.
One thing that indicates the strength of storms is the winds they carry aloft. In meteorology, we measure height with pressure. Since there is lower pressure at higher elevations, the lower the pressure in terms of forecasting, the higher the elevation. The elevation isn’t always the same because the exact height of a certain air pressure in one spot will never be replicated, but usually they are around the same area. For example, the surface is usually 1012 millibars of mercury, and the area around Snoqualmie Pass is about 850. Getting back to winds aloft, the 850 mb level winds with this storm will be about 35 mph, which isn’t particulary strong but it is significant. These winds aloft enhance oragraphic effects along mountain ranges. Oragraphic means that moisture hitting the mountains cools and condenses because of the irregular terrain, and clouds and precipitation are formed. The stronger the oragraphic flow, the more pronounced this effect is.

Forecast:
Tuesday: 64 50 partly cloudy, rain developing late
Wednesday: 62 51 rain
Thursday: 61 52 showers
Friday: 65 51 partly cloudy
Saturday: 70 51 mostly sunny

Extended:
Sun sun sun and eventually some rain.

September 21, 2008
Predicted: 59 52
Actual: 64 54

Yikes! I was five degrees off for my high!
This is the type of weather where it is really hard to pinpoint the high temperature because a prolonged shower overhead can mean as much as a 5 degree swing in temperatures (or, in this case not having as many showers overhead). I said that there were going to be showers, but today ended up being a lot nicer than I expected here in Seattle. Other places got showers, especially in a weak Puget Sound Convergence Zone over the mountains, but we were partially shadowed by the Olympic Mountains. I even saw some sun today!
The forecast for the rest of the week is looking on track. No real changes at all except the extended might be a tad bit drier.

Forecast:
Monday: 62 52 few showers, mainly in morning
Tuesday: 67 55 partly sunny with rain developing late
Wednesday: 62 50 rainy and breezy
Thursday: 64 52 showers
Friday: 67 53 partly sunny

Extended:
Some tranquil weather looks in store for next weekend but active weather may be in the long term after that (and if you think I’m wrong I’ll tell you I was talking about those big November storms I kknow were going to get)

September 20, 2008
Predicted: 61 50
Actual: 58 54

We actually got a little more rain than expected. Our slow moving upper-level low pressure system stalled over the area, so what would have been an hour of rain turned into a dreary day. It shouldn’t be too hard to believe that this is the first measurable precipitation of the month as it has been pretty dry. Tomorrow will be similar today except I think there will be a little more in the way of intermittent showers than periods of light rain. The rest of the forecast is still looking on track, and Wednesday looks like our best bet for some more rain and possibly a little wind.

Forecast:
Sunday: 59 52 showers
Monday: 61 52 few showers
Tuesday: 65 52 partly cloudy with rain developing late
Wednesday: 59 50 rain
Thursday: 60 53 mostly cloudy

Extended:
The immediate extended (days six or seven) looks fairly calm with just some clouds and temperatures in the mid 60s, but we could get into some more active weather later into the month and early October.

September 19, 2008
Predicted: 66 52
Actual: 60 54

Grr….
The weather is pretty boring right now. It’s not sunny, it’s not stormy, it’s not cold enough to snow, it’s not rainy enough to flood, it’s not windy enough to knock out power, it’s not warm enough to swim, it’s too cloudy to go outside, and the days are too long to feel secluded but too short to do anything outside.
But somehow I manage…
Anyways, this is probably the weather I hate the most because it is extremely boring. It is sort of a welcome change from these hot hot days we have been having. We are expecting some weak weather systems to be glancing us over the next few days, especially Saturday and Sunday. There won’t be really any widespread rain though, as these weather systems don’t really have any defined fronts to support precipitation. We could get a more consolidated rain later this coming week.

Forecast:
Saturday: 61 50 showers
Sunday: 60 50 showers
Monday: 62 51 few showers
Tuesday: 66 49 partly cloudy
Wednesday: 62 52 rain

Extended:
We may see some sunshine at the end of next week but we can say goodbye to cold showers, shorts, and t-shirts for a while. Enjoy your weekend!
September 18, 2008
This group is back! I wasn’t here much over the summer and the weather then is pretty boring anyway, but I’m excited to do this again hopefully for the rest of the school year. Oh, and in case you haven’t already figured it out, I like weather

So, the nice weather we have had is now coming to an end. Today was cloudy with even some light drizzle in places. The reason why it was so sunny before was that we had a huge dome of high pressure keeping us dry. Now, that dome has moved off to the east and we are getting more of a marine influence, which doesn’t necessarily mean storms for us but it does mean that we will be cooler and more cloudy. We have actually been blessed with the weather we have had. Nice summerlike days are common in September, but to have them for that long is pretty unusual.

Forecast:
Friday: 66 52 cloudy
Saturday: 64 51 showers
Sunday: 63 51 showers
Monday: 63 52 isolated showers
Tuesday: 69 53 partly cloudy

Extended: After a nice day on Tuesday, the door to the Pacific should open back up on Wednesday. Nothing major, but there should be some weak systems coming through. I hate to say it, but I think these last couple weeks were our last of summertime weather.

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