The WxCafe™

Arctic Event Possible

Posted by Rufus La Lone on December 12, 2022

Monday December 12

Well, the extended outlook has taken quite a turn toward Winter. We will present the possibilities knowing that all could change. Before filling your Mug, please accept an opening commentary.

’Table ☕️ Talk' — While the coffee is getting ready, a few comments. Long-time Patrons here (as we’ve started the 29th year of writing these forecasts), know that the crystal-ball weather models used to build our forecasts have lots of variability. A few years ago, one model - the GFS (U.S. NOAA) - underwent revisions and updated ‘code’ to improve the charting of potential atmospheric changes. It is the personal opinion of our staff (me, myself & I), that the variance in model outlooks has widened. Concurrently, the earth’s climate continues to change (as it has always done, human-influenced or not) which may or may not be accounted for in the model projections. We request Patron tolerance for what can be quite a difference in the weather forecast vs what actually happens. As difficult as it is to be ‘spot on’ in forecasting weather for your planning purposes, we will not back off presenting ‘what if' scenarios to help Patrons. Our motto has always been “be prepared, just in case.”

Ah, now the coffee is ready. Mug is full. Onward.

This week’s weather will start out on the calm side, with spotty fog possible along with air stagnation. By Thu Dec 15, high pressure will rapidly build to the E-NE, setting up STRONG outflow WINDS from the Fraser & Columbia Gaps. This will help ‘clear the air’, if you will, but also make traveling east along the Gorge a real grip-the-steering-wheel experience. We will notice a drop in temperature overnight in wind sheltered areas. With the weekend will come the potential for SNOW or a mix of snow/rain. Yes, it is becoming more-and-more probable, if the models verify. Our 'Table Talk' comes into play now.

Dec 18 - 23

Arctic Cold. The E-NE winds will subside briefly early on Saturday the 17th right before the leading edge of an Arctic Cold air mass begins to shift south out of eastern Alaska & The Yukon. Barometric pressure is charting well above 1050 mb (we find it hard to fathom the forecast of 1060s plus mb on the GFS charts). With a surface Low possible along the BC coast following a similar track, SNOW is probable in the Sunday / Monday Dec 18,19 period. The system may not carry much moisture, but it doesn’t take a lot to witness The White. Areas with snow would be Salem north. The air could cool down rapidly west of the Cascades, if the Low trajectory is just right. Generally, though, the coldest event of the season is charting to drop into the PNW and the middle of the U.S. starting this weekend.

The E-NE winds will HOWL Monday through Friday Dec 19-23. A second shot of colder Arctic Air arrives. Seriously, wind damage possible for some trees, as very cold HEAVY air settles into the eastern basins of WA, OR and to the east. The week should be DRY & cold. Single digits temperatures possible east of the Cascades; upper teens to low 20s west side, out of the wind. Right now, the models build such a High Dome of pressure, that cold air will really smash west out of the Gaps.

Another scenario in the Dec 18-23 period is that the first ‘drop’ of cold air from the north skirts east of the Continental Divide, keeping the PNW on the chilly side, with no threat for snow showers on Sunday the 18. However, that second, colder blast from the Yukon, if it happens, would greatly intensify the pressure difference east & west of the Cascades on Canadian Coastal Mountains with WINDS notably stronger than the first shot. Stay tuned

Christmas weekend.

With either scenario, models bring Pacific storms into the region from the west during the holiday weekend. That means the transition from cold to mild will be quite messy. Bad timing. We could experience a day or two of snow, then freezing rain, then rain. The degree of each type of precipitation we have will depend on how which of the forecast discussed above pans out. For now, we are suggesting that snow/freezing rain is possible on Christmas Eve (more snow than freezing rain for NW WA, to start with anyway). Valley RAIN on Christmas Day for west of the Cascades. W-SW winds.

After Christmas - windy and wet, with Pacific storms arriving Mon and Wed Dec 26 & 28.

—> We will keep everyone informed with special statements, if all of the above comes into play

“Have the courage to let go of the things not worth sticking to."

-Rufus

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East instead of South

Posted by Rufus La Lone on December 09, 2022

Friday December 9

The threat for strong winds has changed, as the track of the storms will remain offshore; however, strong east-to-NE winds over the Puget Sound & out of the Columbia Gorge will be in play, at times, so Mug up & read on.

A Low center pressure Pacific storm is charting to drop to approx 979 mb as it approaches north Vancouver Island; however, the storm center will NOT move onshore; instead it will track off the coasts of WA & OR, slowly ‘filling in’ (weakening) as it moves onshore into California late Sunday. Hence, southerly WINDS will be nominal; however, E to NE winds in the Puget Sound will get noticed. We will get some precipitation out of this storm, today (Fri) lasting through much of Saturday. The air mass will cool down as the weekend unfolds, so snow levels will drop below the passes. Quite wet & windy in the far southern portions of OR and into northern CA. Localized fog could reform on Sunday & Monday as winds diminish; temps will be close to, if not below, freezing is the sky clears.

The Tuesday storm, which we mentioned last time a possible wind producer, is now likely to track offshore, posing no threat for wind or much precip on Tue & Wed. In fact, High pressure will build east of the Cascades and set up a STRONG east wind situation as next week progresses. Fraser wind should increase a bit late Tue night, and be a factor for a few days. For east Portland & the Columbia Gorge, the wind will increase daily so that by Fri & Sat Dec 16,17 it could be quite strong. Other than a few showers late Tue into Wed, DRY weather will be the main feature of next week. The winds will ease up by Sunday the 18th.

Our next period of rain could begin during the week of Dec 19-23. Model runs have trended two different ways; 1) a pattern brings another COLD High pressure dome down from interior of Canada setting up a cold & wet, low-elevation-snow threat during that week; or 2) a chilly & damp system drops in from the NW on Tue, followed by a series of stronger, much wetter storms for mid-to-late week Dec 21,22, drenching the PNW before and during the Christmas weekend. Plenty of time to refine this outlook next week.

A White Christmas is not indicated, as of yet, on the long-range charts.

“Money may talk, but today’s dollar doesn’t have enough cents to say very much."

-Rufus

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Hold On Storms

Posted by Rufus La Lone on December 05, 2022

Monday December 5

— YELLOW ALERT for WIND this weekend —

Stormy December wx may be coming. For this forecast, we’ll focus on 4 storms. Refill your morn’n Mug.

A drab pattern is on tap for the first 3 days of this week. Plenty of foggy bottoms and calm conditions. Take advantage, if there is outdoor work to do, as we may be entering a classic stormy December period. Admittedly, we have forecast such a 'run of storms' a few times this fall, to no avail. However, if the models verify, planning ahead will prove prudent. So, what’s the scoop?

1st. Rain returns late Wed night, moving in from the NW. Vancouver Island & southern BC get wet first, then the rain will spread across the rest of the PNW by sunrise Thu Dec 8. It will be a fast moving front, so expect showers to begin by late Thu. It will be a cold front, with snow levels dropping again to low elevations once the front passes.

2nd. Right behind storm 1 will be a potentially STRONG storm hitting from the West sometime on late Fri / early Sat. Just where the very deep centered Low moves onshore will determine which area get the strongest WIND FIELD. Currently, models track No. 2 to make ‘landfall’ somewhere between Coos Bay & Astoria. BUT, as it moves right up against the OR coast, some solutions literally circle the Low up towards central WA coast, then move it back to Astoria area by Saturday night. Complicated and very difficult to pin down details. However, we are not afraid to put out the possibilities; you decide how to plan accordingly. Quite windy conditions may last hours. Center pressure could be in the 980s mb and filling to 995 mb by Sat night; some solutions drop the Low to the 970s by Sat morning. In general, this storm has been on the charts for a few days now, warranting a call-out here.

3rd. Yep, another storm - which could be the WETTEST of the series, is modeled to arrive by Mon morning, Dec 12, with the brunt of the storm hitting the region by Tue. A very deep Low, potentially in the 960s mb!, may form and track just north of Vancouver Island. The WIND FIELD for this storm will be large, so the PNW could be blown around again, although not as roughly as No. 2. (Worth the mention: there have been solutions tracking this storm right up against the NW coast of WA; if this scenario were to verify, wind issues will be greatly expanded and stronger than the second system.)

4th. After a relatively dry Wed and most of Thu, Dec 14,15, another batch of rain will sweep into the PNW late Thu and Fri. Sat the 17th may be dry, with rain on/off from Sunday into the final week before Christmas.

Lots of changes are inevitable, of course, but for now, it will be prudent to plan ahead in case any or all of these strong storms make it onshore. The wx this fall has been relatively tranquil, with long stretches between storms. What is charting now is a rapid succession of storms, some quite powerful, beginning later this week. Hold on.

“It’s best not to see through one another but to see one another through."

-Rufus

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Drier Period

Posted by Rufus La Lone on December 02, 2022

Friday December 2

The twelve month of 2022 has arrived. Many activities & travel plans are set up for the holiday month. We’ll keep you posted on any major wx episodes that may have significant impact. Simply keep that morn’n beverage Mug ready.

Our current PNW chilly pattern will remain in place, with western valleys slowly warming up over the weekend to limit any snow threat. Still, there is enough cold air being drawn in from the east through the Fraser & Columbia ‘Gaps’ to allow for snow showers whenever moisture arrives. Such is the case over western WA this Fri morning. The Low offshore will move south today & Sat, holding the bulk of the precip to the west. A STRONG east wind will develop out of the Columbia River Gorge (and to a lesser extent, the Fraser River Gap), esp on Saturday. It will ease up by Sunday night. Snow showers over eastern OR on Sunday. Overall, the weekend will remain DRY, chilly.

Next week is trending mostly DRY, with the east wind situation returning by late Thu Dec 8th, as another Low tracks south off the coast of WA & OR, bringing more rain to California. The weekend of Dec 10,11 should be dry and, yes, December chilly.

The prevailing model solution for the week of Dec 12-16 is for a return to the threat for very low elevation snowfall and bundle-up chilly conditions. A repeat, if you will, of the past few days. We’ll keep an eye on this. Usually, it means snow in the foothills about town and tough travel going over the coast & Cascade ranges. Expect it to be a wet week.

One aspect our team here is monitoring closely is the shift of a northern Siberian High into position as a precursor for a cold winter Christmas period in the PNW. Not a forecast, just a ponder point for while we sip a morn’n bev.

“If all the cars in America were lined up in a row, someone would pull out and try to pass them."

-Rufus

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Continuing On the Edge

Posted by Rufus La Lone on November 28, 2022

Monday November 28

We will continue on the edge for low elevation snow for the next several days. Time for that refill, Patron.

It’s always difficult to get snow at the surface in the PNW, mainly because we are so close to the Pacific, which holds temps up. The pool of cold air on the east of the Cascades will not be quite as cold as forecast several days ago, hindering our chance for west side snow. However, there will be periods between now & Sunday that may allow for cold air to be drawn west to mix with the marine moisture resulting in a snow/rain mix at the surface, and snow in the foothills.

Showers today will diminish before the next system moves in from the NW Tue & Wed. The mid-week storm will be rather strong, with a Low pressure center deepening to approx 980-984 mb when it is west of Vancouver Island. This will cause surface winds from the south to keep valley floors warm enough to hold off any valley snowfall. That said, depending on the position of that Low, colder air drawn in from the east could keep the air mass cold enough for snow/rain mix, or just snow at times, esp later Wed into Thu as that Low drift south off the coast of Oregon. You’re right: not a definitive forecast, because we remain On the Edge, indeed.

Another ‘repeat’ storm is modeled to follow nearly the identical path on Fri Dec 2. Yep, there will remain the threat for low elevation snowfall. Either way, it will be a very chilly, wet period as this week ends. Sat & Sunday are trending drier, with chilly air mass and a moderated east wind. Sunday night the next Low tracks just off the coast of BC and then right over OR. Rain at the surface, snow in the coast & Cascade ranges. North Puget Sound could see snow/rain mix, as the Fraser Outflow will turn on again, rushing colder, continental air into the region. Familiar pattern.

A classic wet, mountain-snowpack-building pattern will set up for 1st full week of December. A large pool of very cold air is charted to settle over the Gulf of Alaska during the week of Dec 5-9. By mid-to-late week, that colder air will drive wet systems into the PNW, for very low elevation snowfall. Too early to predict valley snow, but, if models verify, snow levels will be quite low (500-1,000 ft). This pattern will be quite different from the current one because the coldest air will arrive from the northwest, hence any chance for snow will not be predicated on an east wind. We’ll monitor this closely. California should get some precip out of this pattern, late week.

As the weekend of Dec 10,11 gets underway, an east wind may develop as High pressure, centered over the Continental Divide pushes air towards the PNW coast. Concurrently, a Low will be moving south off the coast, missing the PNW, contributing to a large pressure difference, which sets up the strong east winds. RAIN should return during the week of Dec 12-16, some of which may be moderate-to-heavy.

Well, that's the current long-range outlook. Change is inevitable, so keep that Mug of yours handy and step back into The WxCafé™️ on Friday for the latest revision.

“The right angle to approach a difficult problem is the try-angle."

-Rufus

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