A “Classic” November Day Monday: Then Coldest So Far This Season

Tomorrow looks like a soaker, especially the second part of the day as a vigorous Pacific frontal system arrives.  Rain should pick up in the 2nd half of the day at the same time a surface low pressure center tracks from off the Oregon Coast to around Seattle.  That gives us gusty southerly wind the 2nd half of the day and through the evening.  Gusts should reach around 55 mph on the Coast and 30-40 mph here in the valleys.  Not a big wind or rain storm, but just enough of each to make for a miserable evening commute whether you are in a car or not.  Note the relatively light precipitation totals (no flooding) for the next 48 hours:

RPM_12KM_Precip_NWOR

The bad news for skiers is that we’re going to see 1-2″ of mainly rain at all the ski resorts (snow above 6,000′ only) tomorrow afternoon through early Tuesday.   Not good.

This is the only rainy weather system we see for at least the next week!  What’s going on?  A ridge of high pressure in the atmosphere is going to take hold across the Pacific Northwest.   This one will be a bit different from the last in three ways.

1. Unusually dry air from the north comes in quickly behind the cold front Tuesday morning.  So the rain will just stop, and then we’ll see dewpoints plummet to the lowest values we’ve seen since last winter.  That’s the measure of moisture in the air.  Models are saying 15-25 degree dewpoints.   As a result, we’ll see lots of sun starting Wednesday.

2.  With the much drier air, fog should disappear in all areas west of the Cascades from Salem north through at least Friday-Saturday.

3.  Coolest airmass so far this year settles east of the Cascades, and now it’s inversion season so it won’t go anywhere.  Cool air will be spilling out of the Gorge.  Highs in the mid-upper 40s west of the Cascades with a dry airmass says 20-25 degree lows later in the week in the colder spots (Hillsboro, Orchards, Vernonia etc…).

The low temps I put on the 7 Day forecast this evening are meant to be representative of the entire metro area, not PDX where the wind will be blowing the 2nd half of the week.  In windy areas it’ll barely get below freezing:

7 Day

 

What won’t be different with this ridging?  That gorge wind will start blowing some on Wednesday, then really ramp up towards the weekend.  We’ve seen that this fall already.  Although this time we’ll get very warm temps aloft along with the cooler air below; a good setup for a very strong gorge wind event Thursday through ????.

As I mentioned on Friday’s post, looks like ridging is going to want to stick around.  Both the ECMWF and GFS are keeping things quiet weatherwise to at least the last few days of November.

Chief Meteorologist Mark Nelsen

20 Responses to A “Classic” November Day Monday: Then Coldest So Far This Season

  1. KAYTHEGARDENER says:

    Could a winter windchill chart be linked to this site, so that the actual temps could be translated into “felt temps”?
    KMC

  2. smithsky@frontier.com says:

    Who has the responsibility of doing the “Play by Play” as the east winds kick in? Rob??? I have to say, there isn’t anyone who makes the east wind engine starting up more exciting than Rob.

  3. pappoose in scappoose says:

    “With 0.03″ of rain, Nov.19 officially lived up to its rainiest day of the year in Seattle title– 90th time it’s rained since 1892 (74%)”

    http://www.komonews.com/weather/blogs/scott/Time-for-Seattles-strange-November-statistical-quirk-232358101.html

  4. Marcustheweathernut says:

    Hey mark, I see the east winds went from strong to just gusty on the 7 day??? Are they not looking as strong now?

  5. AdamInAumsville says:

    00Z GFS cold in la la land…again.

  6. pbo9 says:

    Wow, serious gusts here in North Portland. I would estimate a top speed of 45mph, based on the broken fir branches and whistling wires. Also, the roaring over my roof. Kind of fun. Come on clear weather!

  7. Rob - Southeast Portland says:

    Wind Gusts – *Feel free to add more below
    Lincoln City 67mph
    Pacific City 65mph
    Yaquina Bridge 62mph
    Mary’s Peak 70mph
    Astoria 47mph
    Astoria-Megler 58mph
    Naselle Ridge 68mph
    Megler hill 67mph

  8. alohabb says:

    Uh….where did all the pasts posts go? What did I miss….I was just on here a little while ago

  9. Timmy_Supercell (Klamath Falls @ 4200') says:

    23 / 48 in K-Falls today, a little chilly.
    Not looking forward to the snow..

  10. Lurkyloo says:

    Ummm, I must have missed the drama. Happy Monday, everyone! Not looking forward to cold wind …

  11. BoringOregon says:

    You in!!!

  12. Mark Nelsen says:

    A fresh start…now grow up folks.

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