2 More Warm Days

May 16, 2007

SnapshotAs you can see to the left, a cold trough is approaching for the weekend.  So enjoy the next two days…they should be just about perfect for May.  It appears that onshore flow will remain quite weak through Friday.  I notice little or no stratus along the coastline, so most likely we’ll see mostly sunny skies too.
There were a few thunderstorms over the Elkhorn Mtns. this afternoon west of the Baker Valley, but they petered out pretty quickly after 5pm.  We could get a round again tomorrow in the Blues or Wallowas.
The trough over the weekend will be a chilly one with plenty of showers both days.
In the long range, maps are showing more of a flat ridge next week, giving us warmer temps, but no unusually warm weather for this time of year…Mark

Warmest So Far…

May 15, 2007

Hmmm…I should have stayed with that 85 degree forecast that we had here at KPTV for today all through the weekend.  Amazing what happens when the switch from dry/warm east wind and cooler/moist is delayed a few hours.  Looks like most of the Willamette Valley didn’t hit 80 degrees today.   Here in the Portland metro area where east wind continued until 1-2 pm, temperatures shot into the mid 80s.  Models were slow on the transition (but only by 3-5 hours).  We did not hit a record though since last year on this date we hit 93 degrees with a hot east wind!
A major marine push is in progress this evening, evidenced by wind and pressure gradients.  The gradient from North Bend to Portland is 8.9 millibars at 4pm, one of the higher "SW Push" gradients I’ve seen in the warm season.  Southwest wind gusting 20-30 mph has entered the west side of the valley at 4pm and should quickly swamp the whole region west of the Cascades by 8pm.  It’ll be a very quick cooldown tonight.  I bet it”ll be close to 50 degrees most areas west of the Cascades by 10pm.  Windsurfers can plan on a "dawn patrol" in the morning as 30-35 mph winds blow through the Gorge later tonight and all day tomorrow.
It’s back to weak onshore flow later tomorrow through Friday.  That means the morning cloud/pm sun routine is back.  I do notice that the marine layer is deepest tomorrow and then thins quite a bit Thursday and Friday, so temps will bounce back slightly.
10:45pm:  Okay, I’m back.  Long range maps have backed off slightly on the weekend trough.  Doesn’t look like the end of the world and probably no chance for thunder either so I’ll take that out tomorrow (if Drew doesn’t do so first at 3am).  Looks like June-like weather will return starting Monday with some sort of ridging next week.  Latest 00z GFS is not quite as sharp with ridging Tuesday and Wednesday.  Earlier runs implied we could hit 90 next week.  The big picture says our generally dry/mild/warm May will continue…Mark

Warm Day & Warm Nights

May 14, 2007

SnapshotWhat a range of temperatures today and what a great performance by models.  I admit I was pretty nervous around 10am when the temperature was climbing slowly.  But that downslope easterly wind always does it.  If you ignore the diurnal rise/fall of temperatures down here at the surface, the warmest atmosphere and easterly flow occurs in the next few hours.  So as I mentioned at 10pm, those areas that keep a light easterly breezy tonight are going to be very warm.  I notice that Larch Mtn. RAWS at 10pm was gusting over 40 mph.  And the Gorge gradient from PDX-DLS has recovered to above 3 millibars.  The easterly flow collapses early tomorrow morning and SUPPOSEDLY we get a light southwest marine surge into the interior by midday.  IF this doesn’t arrive, we’ll be 85 degrees in Portland.  But just like last week, I see no reason to doubt all the models on that cooling.  So I figure we’ll just hold steady in the afternoon after a much warmer start to the day.  A strong onshore push brings a much cooler airmass inland Wednesday.  The rest of the week is cooler, but still very nice for this time of year.  Long range models have been showing a very cold trough moving over the Northwest Saturday-Monday.  Well, the 00z GFS has suddenly backed off a bit.  That has happened a few times in the last few weeks.  We’ll see what the ECMWF comes up with on it’s 00z run.  We haven’t seen significant rain in quite awhile (except for far eastside folks like me who had up to .50" or so Saturday night…oops).  Enjoy the sun tomorrow…Mark

I just spent some time reading about last May’s hot weather which arrived on tomorrow’s date.  We hit 93 degrees on May 15th, 2007.  Then lots of thunderstorms around the region in the days following.  Of course Memorial Day weekend was cool and wet!  You can check out previous blogs from the last 18 months such as this quite easily:
Mark’s May 2006 Postings

A Dry? Weekend Arrives

May 11, 2007

Fflood1_2Fflood2_2I found these two images on the NWS website.  They show how destructive flash flooding can be.   Click on them to get a closer look.  Here’s a link to the NWS web site  Flash Floods .  Now on to our current weather.  Water Vapor loop has looked very impressive this afternoon/evening with a nice closed low/trough moving towards the Coast.  But the last few hours I’ve become far more confident on model’s insistence that we’ll see no significant rain or thunderstorms from this.  Apparently most of the moisture is quite high up.  No model has good instability for tomorrow and lifted indexes are quite high which doesn’t help either.  The trough moves through quickly and is out of here by Sunday.
Ridging builds in quickly for Monday and Tuesday.  I just bumped up the Monday forecast temperature based on the MM5.  Easterly flow develops during the day Monday, with some east wind maybe even making it out of the Gorge.  That plus 850mb temps rising to +12 C in the afternoon should push our high to the warmest so far this season.  My "magic chart" based on past 850mb temps vs. PDX high shows a high around 81-83 Monday too.  So confidence is high on that.  IF a late Tuesday marine push holds off long enough, mid 80’s are likely that day.  Then cooler with a quick, but possibly dry trough passage for midweek…our dry spell is going to continue.  Before Mom gets here this weekend I guess I better get the drip watering system working for the season.  The garden is going to need it..Mark

Stormy Day Eastside

May 9, 2007

SnapshotLots of lightning and thunder east of the Cascades today with plenty of lifting in southwesterly flow over what’s left of yesterday’s cold front.  Should be a repeat again tomorrow but more likely the heavier storms will be in the northeast section of the state.
Westside we have another chilly night on tap with low dewpoints and clear skies.  There was a minimum of stratus/low clouds out at the Coast on the last visible satellite picture this evening.  That plus models showing little or no low level moisture in the morning tells me that we’ll start out sunny in the morning.  No significant onshore push Friday and Saturday either, so more sunshine.  Temps don’t get much above 70 degrees though.
Some of you have discussed the possibility of showers or thunderstorms Friday.  That’s due to an open wave moving north over the Northwest from offshore.  This is a good pattern for thunder westside in the warm season, but always tricky to forecast more than a day or two ahead.  Everything has to line up just right (south/southeast flow, moisture supply, low level warmth etc…).  Right now I’m not all that impressed, but that could change.  In general our mild/dry May weather pattern is going to continue the next 7 days…Mark

Marine Air Blasts In

May 8, 2007

LightningdensityVery nice…just as models advertised, a strong marine push in progress EARLY this afternoon.  Looks like McMinnville, Kelso, and Scappoose have already peaked temperature-wise with a strong southwest wind blowing now at MMV and West, NW at KLS and SPB.  Check out the 1-2pm radar loop over NW Oregon;  you can clearly see a surge of some sort coming down from the northwest into central Washington county and coming down from the north through Clark/Columbia counties.  We should see strong west-northwest wind spread across the rest of the metro area before 4pm.  PDX may still make it to 78 or 79, but that’ll be it.  Too bad since we started out very warm this morning…at noon we were running 10 degrees above yesterday!   I’m still watching for any development of showers/thunderstorms over and east of us as the marine air arrives.  Our 12z RPM still showed some sudden shower development on the east side of the metro area late this afternoon.  Other models show nothing.
Models are probably right on showing no massive influx of clouds tomorrow.  Visible imagery at this hour shows no solid marine layer offshore.  So still plenty of sun tomorrow, but it’ll be much cooler….Mark

Warm Weather Arrives

May 7, 2007

SnapshotLadies & Gentlemen…start your gardens!  I just ran over to a "local, yet national" home improvement store to pick up some supplies.  I ended up leaving with pepper, tomato, and strawberry plants;  it must be spring-summer fever!  Of course that’s based on looking at the weather maps too, I don’t usually lose control like that.  After scanning numerous long-range models, most seem to agree that we have a nice stretch of mild weather for the next 7 or more days.  That’s the big-picture this evening.  Of course the devil is always in the details so let’s take a look at the short term forecast first.  80 appears to be a very popular number today…take a look to the left.  It was our first 80 degree temperature of the season at PDX.  The atmosphere overhead actually warms up during the night as a strong ridge of high pressure holds over the West Coast.  850mb. temps reach +15 or +16 Celsius by midday tomorrow, then quickly drop to only +3 early Wednesday.  That’s due to a strong, but dry cold front passing overhead tomorrow night.  So how warm tomorrow?  IF it wasn’t for a sudden upper level cooling and an unusually strong marine push that starts tomorrow afternoon, I would go for about 84.  But models are very insistent on quick cooling to the overhead atmosphere after midday and that marine push beginning earlier than normal…quite possible in early May, unlikely in July.  So just a notch or two cooler is my forecast.  Our model here continues to show a few scattered showers developing in the leading edge of the marine push tomorrow afternoon.  Other models don’t show that so I’m ignoring it.
The big marine push would make you think a cloudy and cool Wednesday following it, but this much drier and well-mixed air coming in behind the cold front, so plenty of sun Wednesday afternoon.  Then we into a morning clouds/PM sun routine the rest of the week as a strong ridge sits over the Rockies and very weak troughiness stis out over the Pacific.  As a result…no rain in the 7 Day forecast again today.  That’s strange for May, but definitely not unprecedented.  We’ll probably make up for it with two weeks of cloudy, cool, wet weather at the end of the month right?  Mark
A small maintenance note…I apologize for the missing/incorrect links on my personal weather page yesterday and early today.  The NWS changed a bunch of their links to text information, which had me badmouthing them…at least to anyone within earshot in the living room.  But at least it made me finally clean some things up and add a few additional items as well.