Sunday, March 11, 2012

Storm Update

Its showtime.   The coastal storm is now rapidly intensifying offshore and winds are increasingly over the coast and over NW Washington.  The latest runs indicate a similar path as previous model forecasts, with the low crossing the northern portion of Vancouver Island.  But the storm is now forecast to be weaker by about 10 hPa (the low is now predicted to be in the low 970s as it makes landfall, instead of the low 960s).   Still a serious storm, but a significant notch lower in intensity.

Here is the latest infrared satellite image. You can see the developing storm with a cloud free notch on its western side...the low center is near the apex of that notch.

We also have water vapor imagery (I rarely have shown this on the blog).  At this wavelength we are seeing atmospheric water vapor, with the dark areas indicating dry conditions in the upper troposphere.  Such darkening is a good indicator of rapidly developing systems.

 Along the coast pressure is falling and winds are rising to 40 kts and more.  To illustrate here are the pressure and wind observations at buoy 46041 off the central Washington coast.

Here is the forecast sea level pressure chart for 4 AM this morning. 975 hPa low moving northward off our coast and intense coastal pressure gradients.


We still expert big winds over northwest Washington, particularly the western side towards San Juan Island and Victoria.  Here is the sustained wind forecast for 8 AM tomorrow (Monday) morning.  The dark blue are winds of 45 kts and there are even red (50 kts).  Strong, but lesser winds, over Puget Sound.  These are very intense conditions for the inland waterways.  Gusts will be higher.


The coast will get hit hard around 3 hrs earlier.   Here are the sustained winds at 5 AM--very strong winds along the coast (50kt sustained and higher).

The NWS Wavewatch 3 model is still predicting waves of 8-9 meters (roughly 25 ft)...see chart below for 8 AM Monday.


With low pressure (which results in higher water level) and high tides at 4-4:30 AM, water levels will be quite high during the morning.  If you are going storm watching on the coast, keep safe--some coastal areas will be inundated and logs can be thrown around by the turbulent waters.

And did I mention the moderate to heavy rain over the lowlands and heavy snow in the mountains (over a yard of the white stuff in the Olympics for example).

8 comments:

cornbread said...

Wind is picking up in Bellingham. Just woke the dog up.

Sweetpea said...

Thanks for the great update!
...blowin' like heck here in the San Juan's (midnight).

Unknown said...

Wind started picking up on Orcas too, about 11:45. Dogs a bit freaked.

I loved the lenticular cloud pictures a couple of posts ago.

Local Honey said...

Super intense right now in the San Juans. Not quite sure how husband and son can sleep through this. I am now rethinking my plan to take the ferry off island this morning....

Zathras said...

You mentioned yesterday that the models have been remarkably consistent, and look at that IR loop, exactly where the low center was supposed to track.
http://www.atmos.washington.edu/weather/sat.shtml

There may have been a little wobble here and there but the average track was right over northern Vancouver Island and it really was remarkable how well the models did spinning that up so fast and taking it right where it ended up. I've been doing this for 25 years, from tearing the LFM and baroclinic models from the difax, to watching the UW mesoscale loops. It is often said that the North Pacific is data sparse and unpredictable, but you wouldn't know it by this model performance.

Ferdi said...

First class storm up here on Sinclair Island. Woke me up numerous times during the night. Fairly high tide this morning too, with logs set adrift on large swells. Too windy to check for tree damage yet.

N. Guilford said...

The wind forecasts on NOAA have been so off this winter--like I've never seen before. Right now, for zip 98220, it says "Today: Rain. High near 43. South southeast wind between 13 and 16 mph. Chance of precipitation is 100%.". We are easily gusting to 60 right now, and have been since 3AM. It's been like this all winter, in one case causing me to lose a major greenhouse because of not doing simple preparations. Why are the NOAA wind forecasts so bad this year?

Zathras said...

For N. Guilford: If you have noticed a change in the NOAA (NWS) forecasts here's a possibility: The forecasters at the National Weather Service spend a lot of time dropping the model output values (for wind, temperature, dew point, sky cover etc etc) into a file system called "the grids." The NWS calls it the "digital forecast." Depending on what model output a forecaster pastes into the grids, and how the automated formatters generate the forecast, you can get highly variable output from the source models. More variable than if a person simply types up a general forecast with less detail, but perhaps more consistency. I think I should only speak as a private citizen from my home computer on this, but in my opinion it is an awkward and time consuming system with costs and benefits that have not yet been sorted out. I cannot say whether it makes the forecast better or worse for your location--but perhaps worse by your account. That said, there are undoubtedly locations (pixel in the NWS grids) for which the forecast has improved.