A Very Warm 4th of July On The Way

July 3, 2018

6pm Tuesday

The weather shouldn’t affect your 4th of July plans Wednesday, but it’ll be one of the warmer Independence Days of the past 20 years.  High temperatures will reach well into the 80s.  Gusty east wind during the morning/midday in the Gorge, Cascades, & east metro means extreme fire danger so be careful with those fireworks!

Today was just about a perfect day with a few patchy low clouds breaking up to sunshine across NW Oregon and SW Washington.  It’s about as normal as it gets this time of year with a high temperature around 77-78 in the metro area.

Of course tomorrow is the 4th of July so let’s take a look at the numbers:

Mark IndependenceDayHistory2

Notice that we average a wet fourth once every 4 years.  Yet we’ve seen only one with measurable rain since 1999!  1998 & 1999 featured cool/showery days, but since that time only 2008 saw just .01″ of rain.  My kids, in high school, have never seen a wet Independence Day!  The past few years…

Mark IndependenceDayHistory3

We’ve seen a very cool airmass drop through the northern Rockies and eastern side of OR/WA the past 36 hours.  Timberline only had a high of 39…on July 2nd!  That cool airmass plus mainly clear skies last night led to a chilly morning.  I saw lots of 40s around the metro area and Eugene’s low of 38 was the coldest on record for the month of July.  I see a few spots had a light frost in Central Oregon too.  That includes Sisters & Prineville with Madras, Bend, & Redmond quite close to that 32 degree mark.

The airmass is warming right now and that peaks tomorrow afternoon before a weak upper-level low approaches the region at the end of the week.  One interesting twist tomorrow is a brief surge of easterly wind over the Cascades and through the Gorge from later tonight through about midday.  In fact gusts at Vista House will likely reach at least 40 mph during the morning hours.  By the way, if you’re headed out there the old highway closes in Corbett area from around 10am-Noon for a parade.  Obviously the combo of dry east wind + very warm temps means even higher fire danger through the early afternoon hours.  Easterly offshore wind plus 850mb temps around +17 by afternoon typically means a high in the lower 90s this time of year.  But tomorrow we’ll see lots of high clouds during the daytime, and that should keep highs in the 80s.  Regardless, it’s going to be a toasty 4th.  But the benefit is that temperatures will be comfortable for fireworks after sunset

Independence Day Fireworks Forecast

Beyond tomorrow, a summer weather pattern continues as we head deeper into July.  The hot ridge establishing itself across the Rockies and 4 Corners region the next few days seems to stay just far enough east to keep real hot stuff away from Western Oregon and Washington.  But temperatures will generally remain above normal for the next 7-10 days.  Note the ECMWF ensemble forecast for highs in Portland the next two weeks:

KPDX_2018070312_eps_min_max_15

Some ups and downs, but the trend is for summer heat to set in next week.  Rain?  Forget about it, unless we get marine drizzle of some sort (like yesterday).  The 2 week ensemble forecast from the ECMWF:

KPDX_2018070312_eps24_precip_360

Only 4 ensemble members show .10″ rain ANYTIME in the next two weeks…that’s mid-summer dry weather.

Have a safe Independence Day!

Chief Meteorologist Mark Nelsen