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).

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