Recommended: Use Adblock to avoid ads.
What to Expect May 5th 2015:
Any fellow weather geeks should be excited by today’s forecast! Scattered thunderstorms are in the forecast for Puget Sound this afternoon and evening.
The cause is (unsurprisingly) an upper level low pressure system that has meandered it’s way onshore. As is typical with these systems, this one is carrying a large blob of really cold and fast moving air in the upper parts of the atmosphere at about 25,000 ft (near airline cruising altitude).
An upper level low pressure system can be described as rotating pocket of cold rising air in the upper atmosphere. These systems are responsible for most of our thunderstorm activity. They are typically harder to forecast because of the lack of frequent observations at those altitudes.
If you follow this blog with any regularity, you’ll find that a great deal of our lightning or hail excitement comes from upper level low pressure systems.
I spent some time to look at some of the most notable thunderstorm events in Washington that I remember during the last few years, and I found that nearly every one was associated with an upper level low pressure system.
March 31st 2015:
A multi-day thunderstorm outbreak took place as a deep upper level low pressure system traversed the Northwest. Some amazing images were captured around the Puget Sound.
August 9th-10th 2013 Extreme Lightning Producer:
On August 9th, an upper level low pressure system was spinning along the Oregon coast, causing numerous thunderstorms across central OR, that eventually moved north into western Washington, bringing with it the best lightning I’ve ever seen.
July 19th 2012:
A very similar situation was in place on July 19th, 2012 when a closed upper level low was situated over the northern CA coast and OR border.
Last week I wrote an article about diminishing water concerns. In less than a week after I published that article, Governor Jay Inslee and the NWS declared drought for 44% of Washington. Why are there mixed messages?
The first reason that this message conflicts with previous information is that the drought concerns are more focused on rural areas east of the Cascades, and in the Olympic Peninsula that rely much more on snow-pack water for agricultural purposes. Like I said in the previous article, our snow-pack is dramatically and historically below normal (less than 25% of normal).
It does appear that the most populated areas west of the Cascades will remain mostly drought free. We most likely won’t have to worry about a water crisis in Seattle or surrounding metro areas this summer
The second reason is that the latest long range climate forecasts released by NOAA show little to no drought relief in the coming months. The summer outlooks for rain in the Northwest are much below normal.
River flows are forecast to be greatly affected by the lack of snow-melt this summer. River flow and water supply models by the NWS are showing some rivers to be flowing at less than 35% of normal. This would impact water treatment plants, fish hatcheries, and wildlife including fish and other animals that rely on fresh river and stream water.
The low snow-pack could also enhance the fire danger this summer by limiting the water that wildland firefighters can use, and also by drying out brush and trees.
El Niño Situation:
On top of all this, the large scale seasonal shift known as “El Niño” is in full effect. An El Niño condition occurs when the sea surface temperatures over the central Pacific Ocean are warmer than normal.
The Climate Prediction Center of NOAA recently forecasted that there is a 70% chance of El Niño continuing through this summer, and a 60% chance of it continuing through this autumn.
What does this mean for us? Well during El Niño years, the Southern portion of the country is wetter, while the northern and Northwest portions become drier. The seasonal outlooks reflect this change, by forecasting drier and warmer trends for the Northwest and wetter and cooler trends for the South.
In summary: The upcoming summer and autumn will likely be much warmer and drier than normal for us here in the Northwest.
There’s been some good news for the western Washington region that will, at least for now, quiet the concerns of local residents. The water outlook for western Washington is looking better.
According to UW Professor Cliff Mass, the recent systems (including the one forecast for Monday), have considerably improved the water situation here.
The national drought outlook has come out for the month of April, and it shows no signs of drought intensification in the western Washington region.
This is mostly a result of multiple disturbances that have loaded up the lowlands with rain, and even the mountains with some snow! The snow-pack in the mountains is still very much below normal, and that may still cause some problems later in the summer. But for now, the reservoirs are full.
A frontal system connected to a strong low, will bring another big batch of rain into the region, and also numerous snow-showers in the Cascade peaks on Monday.
Also forecast, is another convergence zone that may setup smack dab over Seattle on Monday after the front pushes through. This “CZ”, combined with the very cold air aloft may be enough to generate small hail through the Puget Sound region in the afternoon, and late evening.
After this storm is out, we’re looking at a big protective hill of high pressure to setup. The High will fend off any precipitation for the next week. Temperatures also may start rising toward 70 soon!
For the last few days, thunderstorms have dotted western Washington; stunning photographers, weather enthusiasts, and commuters. Lightning, heavy rain, and a blanket of hail struck the I-5 corridor on Tuesday (3-31) and Wednesday (4-1). Continue reading
Some exciting weather may be on the way early this week, and I’ll be watching “from the sidelines” in warm and clear Phoenix, Arizona. A cold front will drop some light to moderate rain into western Washington tonight (Monday), and will also drop the temperatures down a few notches for the next few days. Continue reading
Hey Everyone! The calender has finally caught up with the unseasonable weather Seattle has been experiencing these last few weeks, and I want to welcome you into the first official week of Spring. This week we will continue to see a mixed bag of weather, with the forecast showing the possibility of warm and clear conditions on the approach. Continue reading
This weekend I took a mini-vacation to Vancouver BC, and was unable to update the blog. Upon my departure, the weather in Seattle was forecast to be rainy on Saturday, with a transition period on Sunday; a reasonably straightforward situation that we’ve seen numerous times this season, or so I thought. Continue reading
My claim of the ” the return of winter” in my last article may have been slightly premature or unwarranted. After a few chilly nighttime lows dipping into the 30s, it appears that for the foreseeable future, cold weather is long gone from the Pacific Northwest.
This article, I’m going to briefly describe the forecast for the next few days, and then go over the topics discussed during the Pacific Northwest Weather Workshop. Continue reading
You may have noticed that this Winter has been wet and well above the normal temperatures. You may have even given up all hope for a normal Winter and accepted that Winter is already over. Well, not so fast!
Spring doesn’t officially start until March 20th and Nature is here to remind us that. The computer models are finally signaling a shift in the weather pattern coming soon. By this weekend a cold air mass will begin intruding towards western Washington, butting up against the eastern Cascade peaks.
The result will still be milder than usual with highs in the mid 50s. Night-time lows will drop down into the 30s through the weekend, giving us a little taste of winter. The snow level will drop enough that some ski areas in our mountains might make up a little bit of snow, however likely not enough to replenish the historical lack of snow this season.
Next week will be mostly dry, maintaining mild temperatures.
If you’re interested in learning about the weather or meeting others interested in weather in our region, be sure to check out the Pacific Northwest Weather Workshop being held at the National Weather Service in Sandpoint on Feb. 27-28! If you can’t visit, then you can catch up on all the topics discussed when I write up an article about it when it’s over.