February “Heat Wave” Coming…How Warm?

February 4, 2016

9pm Thursday…

You knew I just had to have a dramatic title like that didn’t you?

HIGHLIGHTS

Sunday through Tuesday, and possibly Wednesday will feature our first taste of “early spring” this year with some record high temperatures likely in spots.

  • Skies should be all or mainly sunny during that period
  • High temperatures away from the Gorge wind areas in the western valleys and in the Cascades should reach 58-64 Monday-Tuesday
  • Highs at the Coast and Cascade Foothills will be up around 70 in spots those two days

 

WHY?

It’s been obvious for the past few days that a big ridge of high pressure in the upper-atmosphere will build over the Pacific Northwest.  That starts this weekend and then continues through the middle of next week.  Models have been in excellent agreement with the general pattern.

MarkJet_Warm_ColdSeparated

Those models have also been in agreement that this will be an unusually to record warm airmass for early February.  Here’s the Salem 850mb temperature (5,000′ temp in C) climatology from the SPC website.

Sounding_Raw

I know; lots of lines.  The thin red lines show the warmest temperature ever recorded for every day of the year at 850mb.  Think of those lines as the warmest temperature recorded on any one date around the 5,000′ elevation.  Notice that from late January through all of March the 850mb temperature has never been up to +16.  Both the GFS and ECMWF models say that on Monday afternoon/evening the temperature over Salem will be around +16 to +17!  That would be a new record (if it occurs) for us.  I’ve highlighted what models are showing in yellow and you can see it in the maps below:

As a result, I’m confident we’ll see temperatures up to 60 or higher in the 3,000-5,000′ range over and west of the Cascade Crest on Mt. Hood Monday/Tuesday.  Not east of the crest and maybe not Government Camp either because of a cool surface high east of the mountains.  You can see it on the maps above.

But what about the lower elevations?

IF it was March with the same atmosphere overhead, we’d see temperatures in the 70s early next week in the lowlands.

IF it was mid-January, I’d expect highs around 45-50 degrees as a strong inversion locks in “cool” air in the valleys.

But we’re inbetween and that’s the temperature forecast problem.  Some sort of inversion will still be present but we’re right on the cusp of the end of inversion season so it’s tough to tell how much we’ll break out of it.  We’ll also have a good 6-8 millibars easterly wind flow through the Gorge, so the areas in the strong east wind zone here in the metro area will likely remain below 60 degrees.

Similar weather patterns in early February 1963 and 1995 DID produce highs into the mid 60s in the metro area so it is very possible we see a 65 degree high somewhere in the lowlands.  This evening’s WRF-GFS run from the UW shows highs Monday in the 60-65 degree range in our area and that’s pretty much what our 7 Day forecast shows.  Earlier this model had shown even warmer temps but this seems more reasonable now.

wa_tsfc.72.0000

Now these have all been just weather nerd details…the big picture shows lots of sunshine Sunday-Tuesday and very warm temperatures…Enjoy!

By the way, record highs at PDX are 62, 64, 62, 65 for Sunday-Wednesday.  We’ll see if we beat one or two of those.

Chief Meteorologist Mark Nelsen


ECMWF Monthly Run

February 4, 2016

Last night was another run of the ECMWF ensembles out to 32 days.  That takes us into the first week of March and it looks mild, or at least ridgy with no sign of stormy weather.  Winter is over if this theme continues.  Well, actually “winter was over around January 5th” will be more accurate if this is the case.  This 2nd half of winter should not be a surprise in a strong El Nino season.  Generally most action happens the first half of the wet season in these years…not always, but often.  For the past few runs I’ve noticed some sort of cool spell around the 20th (give or take a few days), but now on this run the ridge is a bit closer so that has disappeared.

Week1:

500za_week1_bg_NA

Week 2

500za_week2_bg_NA

Week 3

500za_week3_bg_NA

Week 4

500za_week4_bg_NA

The 12z ECMWF and GFS ensemble charts say the very warm weather coming next week will be followed by near average 850mb

temps beginning around Valentine’s Day.

tseries_850t_000-360_Portland

tseries_850t_000-384_Portland

 

More on the record warm temperatures coming early next week in a few hours…

Chief Meteorologist Mark Nelsen