A Soaking, Then Record Warm Temps Again

April 12, 2016

10pm Tuesday…

A nice cold front passed through the metro area this evening dropping temperatures about 10 degrees in just an hour or so.  It hasn’t exactly been a big soaker so far, but considering a lot of us just planted some veggies, any rain is good.  I expect more showers tomorrow and Thursday but unfortunately a huge soaking is out of the question.  Check out the paltry totals from our evening RPM model run:

RPM_12KM_Precip_NWOR

Could April actually end up with below normal rain?  We haven’t seen a drier than normal month since November, but we still have almost 3 weeks of the month to go…plenty of time for rain!

We have another highly anomalous warm period coming up.  It appears we’re headed for record-setting warm temperatures early next week.  This with our average monthly temperature running 5-7 degrees above average!

A strong ridge and split in the jet stream flow will return over the weekend and be held in place by an upper-level low approaching California.  This is the pattern I would have expected to see more of back in our El Nino winter.   Take a look at the GFS ensemble surface temperature anomaly over the next 2+ weeks.

GEFS_Anomaly

WAY above normal Saturday-early next week, then a little closer to normal after that time through the last week of April.   The ECMWF ensembles show a long period of dry weather after our few days of showers:

ECMWF_ENSRain

The blue is the operational model run we all look at and the green is the ensemble average.  Very dry for mid/late April.

Here’s what I find far more interesting; this 2nd highly anomalous “heat wave” coming didn’t even show up on ensemble/model forecasts a week ago!  Not even a hint.  Clearly they are having trouble with this split flow and/or lows diving towards California.  Take a look at the ECMWF ensemble chart from ONE WEEK AGO showing the end of the first “heatwave” and then near normal conditions through the following 10 days:

ECMWF_OneWeekAgo

The TODAY is where we are right now (12th).  Now look at what is forecast from this morning’s run laid on top of last week’s run:

ECMWF_Now

The new/current forecast now has the big ridge where there was no hint a week ago.  Interesting eh?

So how warm this time around?  We know that it’ll be 9-12 days farther into spring thus a slightly higher sun angle.  850mb temp forecasts keep rising too.  Check out the last 3.5 days of GFS run 850mb temps, latest run is the bottom line:

GFS_18z850mbtemps

Note the +16 to +17…that’s exactly what the ECMWF is showing for both Sunday and Monday, and now the latest GFS run (not shown above) is right in line too.  We get offshore/easterly wind at least on Sunday, we’ll see about Monday.  Offshore flow at +16 has produced high temperatures around 83-86 degrees in Portland in mid-April.  Of course very few data points this high up.  Regardless, I’m feeling pretty confident that we would beat both Sunday and Monday’s record highs of 78 & 80 degrees.  Stay tuned.  I’m even more confident that we’ll have a 3rd consecutive dry and mild April weekend…crazy.

This is good news for your lawn mowing of course.  If you forgot to tell your son to mow before leaving for work Sunday (me), you can do it either late Friday or for sure over the weekend.

MarkMowLawnForecast

Chief Meteorologist Mark Nelsen