Windy & Hot Ahead

August 31, 2006

We are going through another dramatic swing from cool & moist onshore flow to hot & dry offshore flow this evening.  East wind has already made it to Troutdale this evening.  Dewpoint at PDX is 49 at 8pm, but 37 at TTD.
North Bend-Spokane gradient which was +5 mb. yesterday evening is now -8 mb (easterly) and increasing rapidly at 8pm.  A pretty deep thermal trough for early September will be in place along the Coast or Coast Range by morning.  KPTV’s RPM-WRF model shows the current 2.3mb easterly gradient through the  Gorge (PDX-DLS) will increase to possibly 6-7 millibars by midday Friday.  That’s unusually strong for the first day of September, more like a late October east wind event.  Wind gusts to 35 mph should spread across the entire metro area by midday, not just near the Gorge.  At the west end of the Gorge, expect gusts of 45-50 mph!  The Coast forecast is tough, I think east wind will make it to the coast at least until midday, so 80 or so is possible, especially north of Newport.  Inland forecast is easy…Hot.  If the east wind is too strong, which is possible, it may be tough to hit 90 at PDX.
Saturday should be a scorcher since the wind ends, which leaves us with a hot/dry atmosphere in place, but no onshore flow either as the thermal trough sits right over us.  So I bumped the high temperature back up to 94 and didn’t lower Sunday as much.
Ridging stays nearby through much of next week, so summer continues…Mark


Cold Nights & Warm Days

August 30, 2006

Classic early September weather coming up just as we enter…September.  Funny how that works.

Trough has moved on east this evening and showers are finished.  Clearing skies tonight + cold & dry airmass means widespread 40′s.  I wouldn’t be surprised to see Battle Ground or Forest Grove down slightly below 40 degrees tonight.
Offshore flow begins tomorrow under a building upper level ridge with light easterly wind through the Gorge, but northerly wind will continue in the Valley.  This should keep temperatures from getting above 80.
Friday a different story with our first strong easterly flow of the early Fall season.  MM5-UW shows 4-6 millibars easterly pressure gradient through the Gorge.  In the warm season this should send gusty east wind out across the metro area during the day Friday.  Peak gusts probably 25-30 mph.  40-45 mph more likely at the west end of the Gorge.  I used to hate that when I lived in a windy spot near Corbett because it would knock down my corn before it was ready in September….But I digress.  Thermal trough with much lighter easterly wind will sit over us all day Saturday, so that should be the warmest day.
A change in the maps means not so hot the rest of the weekend, but more warm/hot weather later next week.  The ridge is going to get knocked down and pushed east a bit Sunday-Tuesday, then it rebounds right over us Wednesday-late next week.  It all adds up to a bunch more summer…Mark


A Bit Nippy

August 29, 2006

A chill in the air this evening after the MEGA-MARINE PUSH last night.   You know it’s cold when at 5pm on a sunny August afternoon it’s only 66 degrees in The Dalles!  Timberline Lodge at 6000′ in the Cascades dropped from 75 yesterday afternoon to foggy/cloudy/drizzly and 38 at 5pm.  What a change in 24 hours.  So we are obviously at the bottom of the temperature roller-coaster this afternoon.  We head uphill again on Thursday.
I had .12" rainfall at my home (in the perpetual rain forest again), but the next highest I found in the metro area was .10" at Eagle Creek and .04" in Beaverton.  Most spots had nothing.  A repeat is possible tomorrow morning as a secondary trough of low pressure slides through.  Our RPM model here at the station says a few weak showers may pop up over the Coast Range tomorrow afternoon and move out over the Valley.  Sounds good since it was right last time it did that (in June).  Then thats it for moisture as the trough kicks out.
As several of the "regulars" alluded to in the vigorous discussion below, clearing skies tomorrow night with building high pressure but a resident chilly airmass should give us a real taste of Fall temps by Thursday morning.   Then summer comes back big time over the weekend and next week.
Strong offshore flow develops early Friday and continues through Sunday morning.  Easterly wind will make all across the metro area (definitely a Fall pattern there too) during the day Friday and maybe all the way to the Coast.  So we’ll warm up quickly again just like last Friday’s jump from 69 to 85 in one day.
No real obvious or sharp end to the heat & warm weather is in the works next week.  Ridging hangs nearby, so the first week of school looks more like summer.
For you number freaks;  We’ve had 19 days above 90 degrees here in Portland this summer.  The all time record is 23 days back in the hot summer in 1987 (ahh, the first summer of freedom after high school).


Down the Roller Coaster

August 28, 2006

Up, down, up, down…interesting 2nd half of summer eh?  Something for everyone.

Major marine push already in progress at 5pm.  I see the North Bend-PDX gradient is 7.3 mbs already!  That’s good even for 20 mph southerly wind in midwinter, so we should see a rapid cooldown this evening.  Dramatic cooling in the upper atmosphere in the next 24 hours two as a sharp trough moves through the Northwest tomorrow & Wednesday.  It should suffice to say that tomorrow will be a VERY good day for windsurfing in the Gorge (I used to to that before marriage/kids/home improvement etc…).  Gusts to 50 mph from The Dalles to Arlington are likely.  The marine layer quickly thickens to well above pass elevations by midday too.

Rain is unlikely, but I think central/eastside metro area will see trace-.03" or so each of the next 2 mornings.

Then, it’s back to "September" heat.  It’s clear on the maps this afternoon that this weekends warmup will be a "fallish" pattern, not summer (same end result).  The sharp thermal trough develops out that the coast instead of in the valley Friday.  And surface high pressure builds over the Rockies (their first cool airmass since spring).  The combination will bring the first widespread early fall/late summer easterly wind to the Gorge, Cascades, Coast Range and metro area Friday & Saturday.  So enjoy the cool weather before the heat returns…Mark


Last Weekend of August

August 25, 2006

I love summer, but I guess all good things have to end.  This is the last weekend of August.  That means next weekend is September, Jerry Lewis Telethon here at KPTV, the kids go back to school right after that etc…

So I guess we end with more heat.  Weak thermal trough develops near the Cascade Foothills tomorrow, then shifts into the Valley for all day Sunday.  I expect about 5 degrees warming tomorrow and maybe another 2-4 on Sunday.  Then a quick drop Monday as onshore flow kicks in strongly during the afternoon ahead of a trough.  Our RPM model here (and UW-MM5) shows at best a 1-2 mb. easterly gradient through the Gorge.  East wind will only be felt in the Cascades and west end of the Gorge.  Mostly likely it won’t even make it to Troutdale Sunday.  We are entering the season (late August-October) where east winds start to strengthen and during warm spells will spread out across the metro area.  But this is not a good east wind event.
Tomorrow and Sunday will be days 17 & 18 above 90 degrees this summer.  The record is 23 days.
Stay cool and enjoy one more sunny weekend…Mark


Back up the Roller Coaster

August 24, 2006

Looks like the marine air’s influence is quickly ebbing tonight.  North Bend-Spokane pressure gradient was 11.5 mb. last night, now it’s only 4.5 mb.  Tomorrow is a northerly wind day and then a weak thermal trough develops Saturday and Sunday right over the Willamette Valley.  As I mentioned last night, not a good east wind event coming up, but just an end to the onshore flow.  So 90-92 is probably the highest we’ll see at PDX in this pattern with 850 mb. temps peaking out around +20 to +21 C.

Nice trough forecast next week looks pretty strong on the ECMWF, my model of choice lately, so I threw some showers in the forecast Wednesday-Thursday.  Showers the last 2 days of August with solid marine atmosphere should keep temps in the 60s too.

I’m off to create some weather graphics.  I noticed we’ve had quite a string of sunny weekends, so I’ll talk about that at 10pm…Mark


The Answers III

August 23, 2006

One more set of questions for tonight, but first some weather.

I often feel as if I live in a rain forest.  Not so much the last 2 months but that feeling returned today.  I awoke to steady light rain this morning (not just drizzle, but actual rain) and ended up with .07" at my home at 1000′ above Rooster Rock park (no it’s not a mansion).  I see Camas had .03", but PDX & TTD only got a trace.  I’m sure it was caused by that disturbance that moved through Central Oregon this morning.  Probably just enough lifting of the marine airmass to give us showers up against the Cascades.  Same thing may occur tomorrow as another disturbance moves through the Northwest, keeping the thick marine airmass in place.

I’ve bumped up weekend temperatures a bit since ridging is pretty strong on both ECMWF & GFS.  850mb temps peak around +20 on Sunday.  Not a good east wind event, but light easterly flow especially Saturday.  We are crossing into the time of year where we need a decent east wind over Cascades/through Gorge to really max out our temperatures, since it gets tougher to break the nighttime inversions in September.

So…2 more questions:

Q.  How often do you interact with other forecasters on the other stations?…Charlie

A.  Depends on who it is.  Obviously the forecasters I’ve worked with I already know and I’m much more likely to pick up the phone to chat (Rod Hill, Jim Little, Pete Parsons).  Others I may see from time to time at Oregon Chapter AMS Events or maybe the national AMS Broadcasters Conference or even local media karaoke midnight events (those DO actually happen).  I haven’t met 3 or 4 of the local weather people.  Maybe we should just have one big wild weather party?

Q.  When you cover the big snowstorms, are there beds/showers at the station, or do you go home?…Charlie

A.  There is a couch and shower in one room and KPTV does have the newest station in town so it’s not too gross actually.  And during the big ice storm event in January 2004 I did that for one "night", which consists of about midnight-3am sleeping.  But the station always just pays for a room at a local hotel here in the same business park, even if it’s just for a few hours.  You just have to make sure you bring enough suits, ties, & undies.  Of course I prefer to go home unless it’s a short overnight turnaround.  I’ve driven the 37 miles from Beaverton to the Gorge in an ice storm and it’s never taken me more than 1 hour, mainly because there are NO other vehicles on the road at midnight during a storm…Mark


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