Halloween Forecast!

October 29, 2009

9:40 P.M.

People have been begging me to do a forecast for Halloween, so write a forecast I shall .The good news is that Halloween should be fairly dry! But there could be a couple showers roaming throughout the area.

Let's talk about the first event. Tomorrow is a very, very big day for my saxophone teacher, Steve Treseler. He is getting married! And, at this point, it looks like he will be under dry skies. After about 8 o'clock though, when the drunk toasts are over and everyone stumbles back into their vehicles oblivious to what they just said, the rain will start to fall. This rain is the same rain from the remains of tropical Neki, it will just be the cold front.

This system is pretty big area-wise. Last night and today, we got warm frontal precipitation and are now in the "warm sector" of the storm. That means freezing levels are at 10,000 feet or so. Once the cold front comes swinging through though (should be about 2 A.M. Saturday morning), temperatures will drop and the steady rain will cease. Here is a diagram of your typical mid-latitude storm system, and the warm sector is the dry area between the warm and cold fronts.

It's rare to have a completely dry Halloween in Seattle, and I don't think it will be any different this year. However, most of you should be dry. We will have a few showers around, especially in the mountains and north by Everett in a convergence zone, but these showers could pop up anywhere and put a damper (literally :P) on your Halloween night. All and all though, it looks like a pretty dry forecast.

The extended is just rediculously complicated as the models are about as inconsistent as I've ever seen them, but we could see a little bit of a dry period after Halloween.

Of course, you'll know what I'll be wishing for.

Charlie

Flooding Thursday into Friday

October 27, 2009
3:07 P.M.

I hinted at flooding at the middle of this week in one of my posts last week. Then, that same storm transitioned from a minor windstorm to a major windstorm with heavy rain and flooding to practically nothing. Now, we are back with the idea of flooding, with some wind to boot. There are many reasons why the models have had such a difficult time with this moisture and the storm system they are forecasting it to produce, but the biggest reason is that it has residual moisture from Typhoon Neki in it. Models generally have a hard time dealing with tropical moisture. This model shows the precipitable water values in the atmosphere at the time (the total amount of water vapor in inches in a given column of the entire atmosphere).

Here, you can see the 24 hour precipitation amounts for 5 P.M. Thursday to 5 P.M. Friday. It looks like the Puget Sound basin will be rain-shadowed from Everett South (usually it is the other way around). The mountains, on the other hand, will see tremendous amounts of rain. I would not be surprised if isolated spots hosted storm totals as high as eight inches, locally even higher. We'll be dry tomorrow but the rain will come in late that night and continue into Thursday for the lowlands, while it looks to be a mainly mountain show from there on out.

Thanks,

Charlie

Even more inconsistencies

October 25, 2009
11:55 P.M.

Hello fellow weather enthusiasts. Today I am going to talk about the inconsistencies in the weather models regarding the Thursday storm (the same one that I talked about last week, showing a diagram of it way out in the Pacific, possibly leading to flooding over the Pacific Northwest). As you can see with the picture below (again this is exempt to people reading the facebook blog), models used to show an extremely powerful and vigourous low pressure system (around 950 millibars).

That's equivelent to an extremely strong category 3 hurricane. The models showed it stalling and weakening off our coast, but bring it 300 miles closer or so and we could of been talking about a major windstorm in our area.

Now, the models show it heading up into the Alaskan panhandle, a ~1200 mile difference in track. They also show it much weaker, around 985 millibars. (see pic above)

Bottom line: at this point we don't really know what is going to happen, although a weaker storm to the north seems most likely. Stay tuned!

oh boy

this is andrew making the weather happen for the future and let me tell you all, people are in for a surprise this weekend; hurricanes, snow storms and even a small koolaid tsunami will be hitting the beautiful NW this weekend!

...not really.

what you should be expecting is some potential sun on saturday (a good time to get out) and more than likely more of the great Seattle gray. have a chill weekend guys!
-an

A Quick Update

October 22, 2009

5:02 P.M.

I just wanted to let you guys know of a couple changes in the forecast. First of all, Friday looks wetter for some and drier for others. The front is expected to not stall as much over Vancouver Island, so we will get more rain while they will get less. However, due to the westerly flow of this storm system, the central Puget Sound area will be rain-shadowed (as opposed to places north like Sequim that usually get it more). The diagram below shows the 3 hour precipitation totals from 2-5 A.M. Notice the large hole in precipitation over Seattle.

Nevertheless, things should "even out" precipitation-wise later in the evening as a Puget Sound convergence zone will settle down over Seattle, while all the other places will be clearing up. It's as if we just cut and pasted our rain a couple hours ahead.

We are still looking at a storm Sunday and then some mountain showers with chillier temps afterward. The models, as previously stated, have been inconsistent, but after a brief break early next week we could see another storm Thursday the 29th.

Charlie