Cut-Off Low may bring a marine surge one day early.

by Mike Godsey, mike@iwindsurf.com
Cut-Off LowAndSherman

Hi Gang,

I just updated the videos below since it is looking more and more likely that a marine surge is developing just south of the Golden Gate. Look at second video!

Don’t you just hate it when forecasts like mine last night and Claire’s this morning have Hedges and Notes in them that seem designed to allow the forecaster to weasel out of a crummy forecast.

For example:

Note: Late this afternoon a tiny upper Low approaches the Bay Area and increases the SW flow just aloft. There is a chance that this could ….

One reason we sometimes have to waffle is that we see something in the models out in the pacific that could really change the Bay Area winds. But out in the Pacific there are no weather balloons and no sensors. So we have to rely on the various types of satellite imagery to confirm the feature proposed by the models.

In this case there is a tiny Cut-Off Low SW of the Bay Area. The models have this in a position that it could really increase SW flow and Sherman Island winds tomorrow at dawn or even this late afternoon if it arrived early.

You can see the models version of the Cut-Off Low in the to video.SaualitoBeginningOfmxANIM

The problem is that models are unable to predict Cut-Off Lows accurately since they have lost their connection to the jet stream. So we usually turn to the water vapor satellite imagery where you can normally see the clouds swirling in a counter-clockwise fashion around the Cut-Off Low.marine surgeCut-Off Low

But this Cut-Off Low has almost no moisture associated with it so it is almost invisible in the satellite imagery. However I can see that it must be close since down at the surface there is marine surge like fog moving up the coast and a sliver of fog just reached the Golden Gate. And the way it is stacking up on the Marin Headlands tell me it has a SW cant. The bottom video shows what the Cut-Off Low has done to the marine layer clouds. It is hard to see in the first part of the video but you can barely make out the marine layer clouds shooting up the coast. One dawn occurs you can clearly see the clouds that are lapping at the Golden Gate and the Marin Headlands.

So I would keep an eye on the Larkspur, Pt. Isabel and Sherman Island sensors late this afternoon since that NOTE may come true.

Even Weasel words have their value.