Friday, January 15, 2010

The First Coastal Wind Event

The latest model runs have come in and the first major coastal wind event looks like it will hit southern Oregon/N. CA during the middle to late afternoon on Sunday (see graphic below of sea level pressure and wind speed at 4 PM Sunday. These are sustained winds (averaged over roughly 10 minutes)...not gusts, which can be considerably higher. The reds are sustained winds of 50 kts (hurricane strength winds are 64 kts or more). Certainly, the gusts will make that. These strong winds are associated with a tight low that moves up the coast, while weakening. By 4 AM the low and strong winds will reach Washington (see other graphic).


The Medford NWS folks have put out this statement:
LOW PRESSURE IS EXPECTED TO STRENGTHEN WEST OF THE COAST SUNDAY
AFTERNOON THROUGH SUNDAY NIGHT. WHILE THERE IS SOME UNCERTAINTY
WITH RESPECT TO THE STRENGTH AND LOCATION OF THE LOW...SOUTH
WINDS ARE LIKELY TO INCREASE TO NEAR WARNING LEVELS ALONG THE
COAST SUNDAY AFTERNOON. AT THIS TIME...THERE IS THE POTENTIAL FOR
SUSTAINED WINDS REACHING 30 TO 50 MPH WITH GUSTS 50 TO 70 MPH...HIGHEST
ALONG THE COASTAL HEADLANDS AND ALONG THE NORTHERN CURRY COUNTY.
COAST.

There are still at number of additional strong systems later in the week and
uncertainty is considerable.

5 comments:

Karin Corbin said...

Poor folks in Eureka, they just got an earth quake now they have a hurricane coming. Wonder what Pat Robertson will say about that.

Kevin Purcell said...

Cliff: Is there a simple (handwaving?) explanation for the intense winds due east (and slightly north of east) of the low in the 00z plot? They seem to be especially squashed up against the coast.

I generally expect (as you explain elsewhere) that the most intense winds are to the south and south-west of the low center.

Joseph Ratliff said...

I'm with Kevin, and interested in your take on the intense winds due East as well.

Plus...

For those that may not know about it, Wolf Read has a site dedicated to the various "power storms" we've had up here over the last 80 years or so...

http://www.climate.washington.edu/stormking/

Cliff Mass Weather Blog said...

Kevin and others:
There is in fact coastal accelerations that occur as the pressure variations of the storm interact with the coastal terrain. So you can have the strongest winds near the coast.
I will leave the others of you to muse about Pat Robertson.
The latest forecast model result underline the threat of strong winds tommorrow on the Oregon and then WA coasts....cliff

Mark said...

Cliff, will any of this affect Green River watershed and the situation at Howard Hanson Dam?