Sunday, October 16, 2016

Tidal Surge Notes From the Big October Blow

NOAA tide gauges are worth taking a look at during big storms. The combination of low pressure and wind can have a pronounced impact on water levels. Of course throwing in wave action due to wind can have a big impact on how a given storm will impact shorelines.
LaPush on the outer coast recorded a pressure that dipped below 980.

A bit of different scale for Port Townsend shows a pressure drop down to 982 at roughly 4:30 pm yesterday. 

The low pressure coincided with yesterday afternoon's high tide and caused a tide level to be about 1.5 feet higher than the non weather predicted level or a 1.5 foot tide surge.

Add the wind driven waves and water would have been reaching higher up onto the shoreline than normal.

Alas there are a limited number of tide gauges in Puget Sound so one cannot project the same tide surge having taken place everywhere. Nuance of wind and currents can have marked differences in storm surge. Observations I have made post big storms have found that storm surge can be surprisingly variable. Wind can really push water around and pile it up in some inlets with other nearby sites are much less impacted.

I had a view of Alice Bay southeast of Samish Island in Skagit County yesterday. There was a definite storm surge that brought the water up over the low marsh land separating Alice Bay from Samish Bay. The water was significantly higher than what would be a normal high tide. Perhaps high water in the Strait of Juan de Fuca combined with water pushed up by wind from the south elevated the bay a little extra. The high water pushed a few duck hunters off the marsh a bit earlier than perhaps they wanted.  


grnchile said...

Video showing surf crashing up onto the park/drive at the end of Quincy St in Port Townsend Saturday afternoon:

Dan McShane said...

Thanks for the link