9pm: All Quiet Now

October 15, 2012

Even though the actual cold front is still offshore, wind has died down and radar shows most of the rain is gone.

So that should be it for the night unless we get a brief burst of showers with the cold front. 

The windspeeds WERE impressive along the central coastline, but not much inland:

 

Here are the rainfall totals since midnight:

Hmmm, that wasn’t very exciting was it?  Some heavy showers and a few thunderstorms here and there, but the WRF-GFS beats the RPM on this one.


6pm Update

October 15, 2012

Windspeeds are coming up now in the Northern Willamette Valley with gusts in the 30-35 mph range at PDX and Salem.  Otherwise rainfall is definitely underwhelming.  Some decent amounts down the Valley, but radar is pretty mellow looking at 6:15pm.  No real heavy stuff yet.  The evening commute dodged a bullet on this one.

Cold front can still be seen in IR imagery a bit offshore as a wind switch in the lower-level clouds.  Pressures have just about bottomed out on the North Coast too.

The only lightning so far has been along the coastline and then a cluster of strikes around Government Camp earlier.  Probably some cloud to cloud strikes too since several of you heard thunder.

Chief Meteorologist Mark Nelsen


3pm: High Winds Hitting Coast

October 15, 2012

Peak gusts in the last two hours were 74 mph at Cape Foulweather, 60 mph at Pacific City, and 50 mph at Lincoln City.  Winds peak in the next hour or two, then drop off through the evening out there.  They’ll pick up here in the Valley over the next 4 hours.  Gusts to 40 mph south of Portland and 30-35 mph likely here in most of the Metro area.


Nasty Monday Evening Commute; Downpours, Wind, and Possible Thunder

October 15, 2012

The evening commute will be WET as a very active cold front moves across the metro area.  All models show a quick dump of moderate to heavy rain between 4-8pm as it moves overhead along with south wind gusts to 35 mph in the metro area and 40 mph down around Salem.

We are in a subtropical air mass today; you could probably feel that as you stepped outside yesterday or this morning!  That means plenty of moisture available for significant rain totals, once the right amount of lifting occurs.  That happens as a deep low pressure center tracks to the north this afternoon and the trailing cold front passes over Northwest Oregon during the evening.  Luckily, for wind concerns, the center of the low pressure appears to end up WAY north, near Haida Gwaii (used to be called Queen Charlottes Islands).   So we don’t get anything other than gusts to 60 mph on the Oregon Coast and 35-40 mph gusts here in the Valley.  Still, that’s a lot of wind considering we still have leaves on the trees; there will be a few power outages.

The bigger issue for this evening is the tremendous lifting and instability ahead of and with the cold front.  Lifted index is forecast around -1 or below, CAPE values are quite good along the coast and decent inland, and 700 mb vertical velocity is high.  Add 1.50″ precipitable water and this is what our RPM model shows for simulated radar reflectivity or rainfall:

The key here is that I rarely see the purple intensities show up, and I also notice it’s not a distinct line with the cold front.  This implies widespread convective cells ahead of the cold front.  It’ll be interesting to see how it turns out.  The WRF-GFS model is not nearly as bullish with convection or downpours. 

The screaming message is:  It’ll be very windy and rainy at some point between 4pm-8pm.  Embedded thunderstorms with localized ponding/flooding is also possible.  Glad I’ll be AT work during this time and not traveling.  If you will be on the roads, assume it might take extra time to get home.  Not a huge storm, but a classic wet, windy, and annoying commute.

All of the main action will be done by 8pm or so.  By 10pm the rain is over with just a few light showers afterwards.

Chief Meteorologist Mark Nelsen