Forecasts: Confusing Early Next Week

November 18, 2010

I feel badly for the general public tonight…forecasters (including me) are being unusually wishy-washy about the Monday-Tuesday timeframe.  What a mess!  It’s somewhat unusual to have decent disagreement in the models in the 72-84 hour period (3-3.5 days).  I feel like I’ve been through an invasive TSA-style meteorological rub down the last 24 hours!

First, the next 3 days aren’t really a problem…cold showers tomorrow taper off Saturday, and maybe just a shower or dry on Sunday.  Snow level generally at/above 1,500′.

What’s the problem with Monday?

GFS, and now the NAM since that model runs to 84 hours, both bring moisture back overhead for showers Sunday night and into Monday.  Not a lot, but enough that we would see a couple inches of snow (maybe) if it’s cold enough.  The NAM at face value isn’t quite cold enough.  I notice it has a slightly rising freezing level by Monday morning with a southwesterly wind.  But it’s close nonetheless.

But the ECMWF stubbornly (for 2 or 3 runs now) keeps the action and moisture confined to a stronger wave that comes over us Monday afternoon and night.  It’s also slightly warmer at that time with light onshore flow…marginal.  So the ECMWF would just be dry Sunday night and Monday.

So how do you make a forecast for the public in this situation?  You just make up a bunch of fake weather words, mumble for 3 minutes, make a joke about the anchors…then go home.

Just kidding!  I chose the GFS and NAM approach and ignored the ECMWF.

Beyond that, looks dry as we head towards Thanksgiving.

Nice forecasts in the last post folks…some of you REALLY want it cold don’t you?  Watch out for wishcasting!

Chief Meteorologist Mark Nelsen


Time for Your Forecast

November 18, 2010

Okay, you have 80 minutes to make your own forecast again. BEFORE the ECMWF shows up…I’ll let each of you do what we do each day as professional meteorologists

KEEP DISCUSSING WEATHER ON THE PREVIOUS POST, NOT HERE. I’ll delete anything that doesn’t include just these two:

1. Low/High temp forecast for PDX (only PDX please) for the 21st/22nd/23rd (Sunday-Tuesday)

2. The actual weather for Metro area those days (Example: showers Sunday, 5″ snow Monday, 2″ snow Tuesday). I just made that up, that is not my forecast of course.  And please try to keep it short…no need for a long detailed explanation.  Pretend you have to put it on TV.

-You have until 10:00pm (that’ll get you through the 00z models except the ECMWF), then I’ll shut off the comments.

Mark