North Pacific Hurricanes

The North Pacific is a source for some pretty impressive low pressure systems. Stick them in the GOM, and they’d look like hurricanes. The one that blew in thisOR-Winds week had a pressure below 1000 mb and winds in the 40-60 knot range, which rivals a category 1 hurricane. The difference, I suppose, is that the warm waters of the GOM produce convective activity that strengthens the low, but this source of energy is missing in the higher latitudes of the Pacific. This storm caused some problems on the coast, but the winds dissipated pretty quickly.

What I wanted to point out about this particular system was the correlation between the pressure gradients and the winds. In this overlay of the SFC Prognostic Chart and the Wind Streamlines, you can see the low in the upper left corner, off the Washington coastline. Just southeast of the low the isobars are stacked pretty close together, but spread out as you move south along the coastline. The wind streamlines reflect the effect this has on wind speeds: southeast of the low, right where the isobars are stacked, the winds peak at hurricane force. North and south of the low, the winds meander around and peter out as the pressure gradient–the distance between the isobars–dissipates.

Do you know what the hatched area that stretches from central Mexico, through Utah and all the way up the west coast on the Wind Streamlines graphic is? Here’s a hint: the wind streamlines image I used was for the 3000 MSL level.