Storm #1, on to #2

January 18, 2010

A nice little storm last night with peak gusts over 80 mph on the coast (expected), and 40-60 mph gusts in the western valleys (unexpected).  Luckily I can claim I was having fun with extended family this weekend; only briefly looking at maps Saturday evening and again last night around…11pm.  So this is one of the times I somewhat “checked out” of the weather scene.  Not a big storm by any means, BUT enough to equal our peak gust of 51 mph at PDX so far this winter.  Looks like there were never more than 10,000 PGE customers out of power, always a good measure of the strength of a metro area south wind event.  Remember the “minor” Dec. 14th, 2006 storm?  That put 250,000 customers out of power! 

This IS a fun weather pattern with deep lows approaching the West Coast and then making a left hand turn.  Fast-moving systems too.  Did you notice how quickly we went from gusty southerly wind last night to a gusty easterly wind today in advance of the next low?  The downsloping flow warmed us up into the 50’s today…some spots up near 60!  Now it feels like a real El Nino setup with major storms into California and a mild January so far up here.

Tonight’s forecast is tricky for storm #2.  Another deep low is just west of Cape Mendocino this evening, a bit farther south and east than forecast by the WRF-GFS.  Supposedly this one (and the following one on Wednesday) don’t move as far north, leaving Washington in easterly gradient at all times.  Northern Oregon barely gets into the “south wind zone”.  In fact when I first walked in this afternoon my thought was “how are we going to get a south wind up the valley tonight?”.  There is little to no southerly pressure gradient at the surface up the valley overnight, even less than last night.  By the way, did anyone notice the peak gradient EUG-OLM last night was only around 8 millibars?  That’s generally a peak gust forecast of 30 mph or so at PDX!  Obviously we overachieved due to strong wind above, a mild airmass, and good mixing due to those heavy showers central/west side of town.  So due to that we decided to say gusts to 35 mph from the south for just a few hours in the middle of the night tonight in the metro area as the south wind punches through briefly…then it’s back to easterly by early morning again.

Another deep low moves up the coast on Wednesday.  The problem is that models don’t/aren’t handling the low pressure centers well (last night’s and apparently now today’s).  So I don’t believe any one model solution.  We’ll take things day by day.

One thing far more certain is a real lack of significant rain this week.  The firehose is aimed and southwest Oregon and California.  Washington barely gets anything this week.

9:30PM Update:

Stormy weather is just a couple hours away on the Central Coast.  What’s going on seems much more clear now based on satellite and model info.  The main low is pretty much modeled in the correct position out near 130W.  But the earlier low (which I thought WAS the main one) is now whipping around (dumbelling) the main low.  It’s so close to the Coast near Coos Bay that it’s almost touching…can’t be more than 30 miles offshore.  It’s now heading north quickly, and should be at Newport 2 hours from now.  Apparently this is the trough (kink in the isobars) seen on the last two WRF-GFS model runs.  Except the model didn’t know there is a closed low instead.  The low passed very close to Buoy #46015 (it’s actually working!), with a pressure around 977 mb.  With this low racing north off the coastline overnight, I feel very good about south wind gusts to 70 mph out there…almost as strong as last night.  Here in the Valley I agree with the NWS putting out a Wind Advisory for the South Valley.  But I think gusts of 40-50 mph are likely a little farther north?  More like anywhere south of Portland.  I see the WRF-GFS has 25 kt. wind all the way up into the southern Metro area with only the weak trough swinging through.  With a closed low it’ll probably be a bit stronger.  So I’m going to adjust a graphic or two up on windspeed.

Chief Meteorologist Mark Nelsen


The Weekend is Here!

January 15, 2010

For some reason it’s seemed like a really long week, even though the weather wasn’t dramatic.  Speaking of that, I see at PDX the temp is now running almost as warm ABOVE normal as December was BELOW normal.  Notice that we haven’t even seen a frost in the last two weeks in the city!  It will cool down slightly next week, but only down to normal at best.  No sign of cold air or snow in the next 7+ days.

As for Sunday night’s low pressure center, clearly some models say we could see strong (or damaging) wind at the Coast.  Others say the low is farther offshore or weak.  It’s still very much up in the air right now.  At least it’s a good reason to jump on the computer this weekend and see how things are looking.  Sorry I can’t add that much more than that.  I’m leaning towards no big wind event here in the Valleys and some sort of windstorm at the Coast with a deeper low farther offshore (like the 00z NAM).  Let’s hope the track of the 00z GFS doesn’t verify with the low 15 millibars deeper!

The deep lows will definitely will be watched closely the next week.  The new 00z ECMWF (which looks like the NAM with Sunday’s low by the way) has the cold trough just to our west and swinging lows up towards us for the next 9 days.

Have a good weekend!

Chief Meteorologist Mark Nelsen


Windy Sunday Night?

January 14, 2010

Not much time left to discuss, but I too did notice the 00z GFS and 00z GEM (Canadian) both show a very deep low moving right up the Oregon Coastline on Sunday night.  The 00z WRF-GFS shows a significant windstorm on the central/north Coast.  I think I counted 24 millibars from UIL to OTH around midnight…and it’s a fast mover too.  Great ingredients for a windstorm out there.  However, details in the 250mph jet approaching the Western USA Sunday and Monday are most definitely changing from model run to model run.  I wouldn’t be at all surprised if future runs back off.

The 00z ECMWF and 00z NAM did not have such a deep low close to the coastline, but it’s definitely a development to watch.  It appears that as we go through the rest of the week the lows stay farther south, taking most of the rain and all of the wind with them.  In fact east wind is far more likely the rest of next week.

Chief Meteorologist Mark Nelsen


Poor California…

January 14, 2010

I just saw this on the HPC website, referencing the very stormy and wet period coming up beginning late this weekend down south:

“THIS EVENT HAS THE POTENTIAL TO APPROACH OR RIVAL THE JAN/FEB 1998 EL NINO EVENT IN CENTRAL CA AND THE JAN 1995 TIME FRAME FOR SOCAL. QPF TOTALS FROM MODEL GUIDANCE ARE VERY HIGH WITH AN OVERALL RANGE OF 7-12 LIQUID INCHES DURING THIS FORECAST PERIOD OVER COASTAL REGIONS/SIERRA. EXPECT CONSIDERABLY HIGHER AMOUNTS OVER A MULTIDAY PERIOD WITH 10-20 INCH MOUNTAIN AMOUNTS WITH EVEN HIGHER OVER FAVORABLE TERRAIN. SIERRA MOUNTAIN SNOWS MAY BE IN THE 8-12 FOOT RANGE. AS THE JET CORE SHIFTS SOUTHWARD THE HEAVIER PCPN WILL BE MORE CONCENTRATED INTO SRN CA WHERE SIMILAR RAINFALL NUMBERS MAY OVER ESPECIALLY OVER FAVORABLE TERRAIN. SOME LOCAL FAVORED TERRAIN AREAS WILL MOST LIKELY APPROACH 20 INCH LIQUID AMOUNTS DURING THIS PERIOD WITH THE EVENT CONTINUING PAST OUR 7 DAY RANGE YIELDING EVEN HIGHER TOTALS. VERY HVY SNOWS CAN BE EXPECTED OVER HIGHER TERRAIN AND A FLOODING/MUDSLIDE PROBLEMS APPEAR LIKELY. A HEAVY RAIN THREAT FOR AZ APPEARS IN STORE THURS INTO SAT. SEE CPC THREATS ANALYSIS AND LOCAL NWS OFFICE STATEMENTS/ADVISORIES AND EVENTUALLY WARNINGS. HIGH CONFIDENCE EVENT WITH PAC RECON REQUESTED.”

I think we know what the big weather news story will be by the middle of next week! They have been in a long-term drought down there for years and could use a good soaking, but this probably isn’t quite what they would like to see.


Deep Weather Thoughts

January 13, 2010

Actually I don’t have any real deep thoughts about today’s weather. A nice surge of southerly wind. I put the peak gust map to the left. Looks as if Aurora had top honors with a peak of 48 mph. The 38 at PDX and 46 at SLE are the highest since before Thanksgiving. That does show that we haven’t had a good storm cycle (regular systems moving through on a westerly jet) since the intial one that started the wet season the first half of November.

So…the big question is “do maps for next week show us finally entering a long wet period?”. Maybe or maybe not. I was encouraged last night at this time, but the recent 18z/00z GFS is a bit more disturbing if you want active weather up here in the Pacific Northwest. The first thing that jumps out at me is both the 00z NAM and GFS now show far more splitting Saturday and Sunday; and much warmer 850mb temps. It had looked as if we’d get some decent snow in the Cascades this weekend, not heavy, but at least 5-10″. Now with warmer temps, Saturday could just end up being mild and partly to mostly cloudy.

Beyond that the other thing I notice is how far south the strong jet punches into the USA. Sunday through Tuesday it’s aimed not just at California, but Southern California and Northern Baja! That leaves us on the far northern fringe of the storms…our coastal waters appear to be the graveyard for deep surface lows that unload on California. For example last night’s 00z and the 12z GFS was awfully close to windstorm territory for us with a few lows. But now the 00z GFS has lows farther south and much drier conditions overhead, although generally cool temps hold firm. I’m just thinking that the next few days our models will back off slightly more, and we could easily end up with a dead weather week…one that showed so much promise just a day or two ago. Geez, I don’t mean to bring everyone down, just pointing out the possibility. Plus, someone suggested I shake things up a bit on here, so there you go…discuss.

Chief Meteorologist Mark Nelsen


Gusty Wind Arriving

January 13, 2010

It’s good to see the forecast turn out nicely.  A good burst of southerly wind is moving up the Valley at 10am.  This is from the low pressure system just about straight west of Willapa Bay on the south Washington Coast.  I see gusts of 40-50 mph from Salem south.  That’ll spread north into the Metro area in the next two hours.  Gusts to 40 mph are likely here for a few hours.  That’s generally not a damaging wind but the strongest south wind we’ve seen since before Thanksgiving.  Say goodbye East wind!  At least for 24 hours or so.

PGE already has 15,000+ customers out of power down in the Central Valley.  Looks like some trees haven’t been “pruned” by the south wind this winter.

Ughhh!  For some reason no 10am observations available…really bad timing.  Would be nice to know what the peak gusts are this hour in the Valley.

Chief Meteorologist Mark Nelsen


Rough Evening

January 12, 2010

Apparently I infected the weather center PC with virus or malware this evening…totally screwed up. Then Viagra ads started popping up as windows opened…nice. We DO have a nice little change in the forecast this evening. It’s not exactly a powerful storm, but a nice low pressure center moves north through our offshore waters tonight and tomorrow morning it arrives in Western Washington. There is a real nice pressure gradient straight up the Valley by late morning tomorrow. We haven’t seen a south wind gust over 30 mph at PDX since just before Thanksgiving! Hopefully I read the climate data correctly, but it shows how we’ve been missing good westerly flow for quite awhile. Anyway, a gradient of 9 to 12 millibars should produce gusts in the 30-40 mph range. Nothing too exciting, but we’ll take what we can get.

Beyond that it’s pretty quiet Thursday through Sunday. We get “leftover” rain Sunday as a system runs into California. They will really be under the gun next week. I see the 00z GFS seems slightly farther north with deep lows approaching the coastline next week. Something to keep a close eye on. That’s it; out of time for this evening.

Chief Meteorologist Mark Nelsen