Spring is Finally Here

Today was a very warm day just 2 days after our latest recorded snowfall in history at PDX

Today PDX hit 64 and that is just 2 days after a record breaking snow event.
Here is an image of the ducks stadium on Wednesday morning. 

 So the question is, is Spring here to stay? Well yes, let me explain.

Lets start at looking at what an average spring is here in the PNW,

The image below shows our average temperature for the spring months.

If you notice our regions average temperature ranges from 50-60 degrees

now lets take a look at the precipitation

According to this our region receives over 10 inches of rain in the spring months. 

So whats in our future? 

The image below shows the 18z GFS ensemble 850 mb temps (the red line represents average) 

 Notice how most of the ensembles stay around climatology meaning the high temperatures will stay in the 45-65 range through the next 16 days which is very close to our spring average
I will not post for the next 9-11 day due to a vacation I will be on.
My Forecast:

Thanks for reading 

-Michael

Flooding Rains and a Cascade Snowstorm.

After a week of cold wet weather with a few snow showers on Sunday we are continuing this stubborn weather that just wont go away.

Starting tonight a big slug of moisture will begin hitting it us bring lots of rain through the next 2-3days.

So just how much rain? Well models are showing the 3 day rain fall totals reaching near the 3 inch mark. Now if that much rain will fall then there could be some serious flood threats to already high rivers.

The image below is the 3 day rainfall forecast ending Thursday morning

Now this rain will not be a warm pineapple express  but instead a cold frontal 40 degree rain. The thing is this being a cold rain will mean snow up in the hills. Now a usual precip to snow ratio is 1 to 10 inches, which means 1 inch of rain is equal to about 10 inches of snow and if you look at the forecast rain totals above and change that to snow, places in the Cascades could get nearly 3 feet of snow in the next 3 days.

 The image below shows the 24 hour forecast snowfall totals ending 5pm Wednesday   

Ranging from 20 to 40 inches in spots!

Later in the evening on Wednesday as the cold front begins to move things could get interesting. Cold air advection will begin taking place and bottling up cold air along the west slopes of the Cascades. This will lead to lowering snow levels, now if the enough cold air bottles up it could lower the snow level down to the valley floor in the eastern part of the metro area, such as Battle Ground, Gresham, Oregon City, Camas...ect. But for now I am saying that we will only get a rain/snow mix with the snow level staying above 500ft.

Thanks for reading 

-Michael 

Historic Coastal Snow Storm

What a wild few days of weather it has been! Lets start off with the wind.

Early Monday morning a deep low pressure rapidly developed and gave the coastal areas and some valley locations very strong winds.

The image below is a water vapor satellite image of the low

  Here are some of the peak gusts recorded

- Pacific City (87mph)
- Garibaldi (82mph)
- Cape Foulweather (81mph)
- Clatsop Spit (81mph)
- Lincoln City (77mph)
- Cape Disappointment (75mph)
- Cannon Beach (65mph)
- Ocean Park (56mph)
- Salem (56mph)
- Eugene (51mph)
- Portland (49mph)
- Kelso (43mph)

Later on in the day the cold front passed the coast and started to drop the temperatures. Pretty quickly the rain began to turn to snow and stick. Meanwhile here in the Portland area we were getting heavy rain.

In the evening something almost unheard of  happened, Lincoln city was getting dumped on with snow meanwhile Government camp was getting rain

Here are the ODOT images taken at the same time.

. 

Now what caused this phenomenon to happen? 

This was caused by a cold front stalling out just to the east of the Portland area and providing lots of moisture to the whole area, but the cold front stalling just to the east of the metro area caused the cold air at the coast  not to be pulled in to our area until later when the front began moving again..

The image below shows the location of where the front stalled out (blue barbed line)

In fact so much snow fell on the cost that it will be one that goes down in the record books

So how much snow did fall?

Coast:

Tillamook: 8.5 inches

Newport: 6.0 inches

Waldport: 6.0 inches

Florence: 5.0 inches

Valley:

Happy Valley: 5.0 inches

Boring: 4.0 inches

Camas: 2.0 inches

Milwukie: 1.2 inches

 Salem: 1.0 inch

SE Portland: 1.0 inch

Forecast:

The next several days are just going to be very wet, models are showing the jet stream taking aim directly at us and bringing us lots of moisture.

The image below is the NOGAPS model showing the jet stream on Thursday

On Saturday and Sunday another cold batch of air will come down, now snow is not looking likely due to the lack of precipitation with this cold air.

 The image below shows the jet stream buckling and allowing the cold air to come down 

My forecast:

Thanks for reading

-Michael

Coastal Bomb

Tonight a major storm in the Pacific will develop very rapidly

 Now this rapid intensification is called a meteorological bomb which means the pressure has dropped 24 millibars in 24 hours.

  Here is an image of the low at 2pm Sunday

It might be hard to see but the small low is at 998 millibars

Here is that low 15 hours later heading toward Van. Island

Notice its down to 974 millibars! That is 24 millibars in 15 hours!  

Now if this storm would come 100 miles more to the east then we would be in for a big storm here in the Portland area. 

Here is the 12z WRF-GFS wind gust forecast

Notice how there are 70+ knot (80 mph) wind gusts along the coast...so if you want to go storm watching head on over to the coast tomorrow, as for us in the valley we will only receive a breezy 25 to 30 mph wind with a few gusts near 40 mph.

Thanks for reading

-Michael 

Back to Stormy and Wet.

Well I hope you enjoyed the last few days of sun because starting tomorrow night the rain is back.

Today was the warmest day so far in 2012, PDX officially hit 65 degrees with some places hitting near 70.

Now tomorrow  as the day progresses clouds will roll in but the the front with the rain should hold till the overnight hours. After this front the jet stream will take aim directly at us.

The image below shows the jet stream taking aim at us on Saturday

As you can see the Jet stream delivers lots of moisture with it which gives us rain.

Now the catch is this jet stream is not moving anywhere, here it is again next Thursday

So just how much rain will we get?

Well the 12z WRF-GFS below gives us 1.5 inches of rain in 72 hours by Tuesday morning

Also on Monday a deep low pressure system will pas to our northwest giving the coast winds sustained near 60mph, now depending on how far west this low pressure will go will depend if the valley will get good wind.

The image below is the 00z WRF-GFS showing the low pressure producing winds of 50 knots of the coast.

My forecast:

Thanks for reading

-Michael

Weather Roller Coaster

Last Wednesday night the forecast went wrong instead of having some light snow showers we got almost a widespread inch of snow with 2 inches in some places.

Now what went wrong?

Models were showing the big surface low moving off tho the east and drying us out, now that did happen but what models did not depict is that small little disturbance (called a vorticity maximum) would approach our area  and give us steady precipitation.

The image below shows the little disturbance approaching our coast.

Now moving on to this week. After a warm and dry day on Sunday a cold front will come though our area on Monday afternoon and drop snow levels down to 500-1000ft once again

The best chance for valley snow will be after about 10 pm till Tuesday morning before the air drys out.

The image below shows the sharp cold front coming through on Monday afternoon

Now the following Wednesday high pressure will build over our area giving us possibly of first 60 degree day.

The image below is the 12z GFS ensembles showing the weather roller coaster then lots of disagreement beyond Friday.

 My forecast:

Thanks for reading

-Michael 

Update on Snow.

As many of you heard already there is a chance of snow tonight and tomorrow.

Now this evening the chance of sticking snow is very low, however tonight around 11pm a cold front will come through and bring the snow levels down to about 500-1000ft 

The Image below shows the placement of the cold front at 4:30pm

What to expect:

Now-11pm:

• Rain/snow turning to all rain
• Breezy winds becoming southerly

 

11pm-11am:

• Rain/Snow showers becoming all Snow
• Accumulations will stay mostly above 500ft
• Accumulations below 500ft will be brief and only a trace -1 inch

12pm +

• Snow showers will become rain/snow showers
• T'storms will be possible as the air will be unstable

Long range:

In the long range models are in disagreement just look at the ensembles below some say warm weather other say it will stay cool 

My forecast:

Thanks for reading

-Michael