Weather Blog

What in the world are 'MOS POPS'?

children enjoying popsicle
Mmmm...MOS POPS?

Blog originally posted Feb. 11, 2010:

I had someone ask me the other day: What in the world are "MOS POPS"?

A frosty organic treat to enjoy on a hot summer day? A new symphony set to debut in the rain forest? No, it's much more boring than that... It's a weather acronym.

The person found it by reading the National Weather Service Forecast Discussion which they update every 6 hours or so. That discussion was originally intended to be between other National Weather Service forecast offices so each one knew what the other was doing. But with the rise of the internet, it has blossomed into a more public discussion since anyone can easily read it now.

(And since it's more in the public eye, the restrictions for those writing it have changed as well. Not too long ago, all words in the discussion were restricted to 3-4 letters max to keep transmissions short. Now, Weather Service forecasters are free to write it conversationally. )

But the discussion is still thick with meteorological jargon that may have you scratching your head, and one of those you'll find frequently mentioned is about "MOS POPS."

To use it in a sentence from the discussion Wednesday morning:

"Models have sped up the next system, which is now due Wednesday afternoon. MOS POPS are quite high for the period 18Z-00Z Wednesday."

In layman terms, MOS POPS are what forecast models are saying about the likelihood of rain. It stands for "Model Output Statistics / Probability of Precipitation(s)"

A MOS is taking what a forecast model has generated for a region, and plucking the data for a specific location and turning it into a table format. For example, this link: shows a MOS for Seattle. You can learn how to decode it here for the extended GFSX MOS, or decode the short term GFS MOS's here.

Probability of Precipitation is basically the rain chance the model gives for that period. So "P24" means a 24 hour "POP" and a reading of 84 means an 84% chance of measurable rain during that period.

So if "MOS POPS are quite high for the period" that means models indicate a high chance of rain. ("18Z-00Z" is the time on "Zulu" time, or the old GMT time. That's 8 hours ahead of PST and 7 hours ahead of PDT.)

Also of better help, the NWS has started issuing a Graphical Forecast Discussion where they augment the written text with charts and other graphics to help explain what is going on. That product will also help with some of the mysterious acronyms that still make it into the discussion from time to time.

HV ANY OTR QSTNS ON WX SVC ABRVS? ASK AND I'LL TRY TO ANSWR :)

Why was a rubber chicken sent to the edge of Earth's atmosphere?

Why was a rubber chicken sent to the edge of Earth's atmosphere? »Play Video
Camilla at about 115,000 feet. (Courtesy: NASA & Earth to Sky Calculus Class, Bishop, Calif.)

Blog originally posted April 23, 2012

What do you do if you're a group of science-minded middle and high school students who want to study the effects of a solar flare?

If you're part of Dr. Tony Phillips' Earth to Sky Calculus class in Bishop, California, you strap a rubber chicken to a weather balloon and send it 115,000 feet up to the Earth's stratosphere -- right on the front door to outer space.

A 'dream come true': UK photographer gets aurora and volcano in same shot

A 'dream come true': UK photographer gets aurora and volcano in same shot
The Northern Lights dance behind Icelandic volcano Fimmvorduhals. (Photo by James Appleton. Used with permission)

Originally published March 5, 2012

UK photographer James Appleton had a dream: To capture the beauty of the Northern Lights in the same photograph as the awesome power of a volcano.

And when the Fimmvorduhals volcano began erupting in Iceland -- one of the world's best places to see the Northern Lights -- he knew he had to make a very challenging but ultimately rewarding trek to capture both events simultaneously.

Florida waterfront condos literally create their own weather

Florida waterfront condos literally create their own weather
"Condo fog" clouds form along waterfront of Panama City, Florida on Feb. 5, 2012. (Photo Courtesy: JR Hott, Panhandle Helicopters)

Scott's Note: I am taking a little time off so I'll be posting a few of my past blogs to fill in the gap.

Blog originally posted Feb. 7. 2012


How would you like to live in a place that not only has a stunning view of the Gulf of Mexico, but creates its own weather?

Check out this photo of individual fog wisps climbing over a line of tall waterfront condos, taken Sunday afternoon by JR Hott of Panhandle Helicopter in Panama City, Florida.

For those tired of cool springs, the blues are literally going away

For those tired of cool springs, the blues are literally going away
Ttulips bloom near Seattle's Space Needle. (Photo: Jonathan Cooper, Seattleimage.com)

Even though technically, for Seattle at least, temperatures have been near to even a little above average since the start of February, if you ask around, many would say this spring is well on its way to being the third in a row and fourth of the past six that have gone down as cold and rainy with the frequent cloudy, drizzly days.

Well, long range models suggest this spring is about to make an about-face and warm things up a bit.

The first inkling will be much warmer weather expected for the middle of next week, with highs expected to climb well into the 60s if not some 70s amid plenty of sunshine.

Is sunny, warm weather ever a bad thing for the Skagit Valley Tulip Festival?

Is sunny, warm weather ever a bad thing for the Skagit Valley Tulip Festival?

Thousands flock to the Skagit Valley each April during their annual tulip festival to see the breathtaking rows and rows of colorful tulips and other flowers.

As you might imagine, playing host to the world means keeping a keen eye on the weather for all the incoming guests, while at the same time crossing fingers that Mother Nature provides the need sun and rain to make the tulips their very best.

I always wondered if the weather in March and April affected how the tulips would grow each year -- if it's sunny and warm for too long or if it rains for four weeks straight, can it damage the bulbs or, worse yet, wipe out the show? Can you gauge how well and how long the tulips will remain in bloom based on the weather leading up to and during the festival?

Skagit Valley blessed with perfect climate for tulips

Skagit Valley blessed with perfect climate for tulips
The sunset nestled behind Roozengaarde's field of Ile de France, Negrita, and Dynasty tulips on April 11, 2013. (Courtesy: Roozengaarde Tulips, tulips.com)

Every April, the Skagit Valley Tulip Festival draws people from around the world to marvel at the brilliant and colorful display of flowers that grace the region's farmlands.

How did this spot tucked into the northwester corner of Washington become the national capital of tulips and an international sensation? By being blessed with some ingenious farmers and the perfect climate for growing tulips.

"The cool, maritime climate that encompasses this area is perfect for bulb growth," said Brent Roozen, with Roozengaarde Flowers & Bulbs, one of the two main farms in the Skagit Valley that grow tulips.

The Skagit Valley sits roughly on par with the latitude of another famous tulip paradise: Holland. While that country is about 250 miles closer to the North Pole, Holland and the Skagit Valley have remarkably similar climates:

Oklahoma town goes from 87° to 27° in 24 hours!

Oklahoma town goes from 87° to 27° in 24 hours!

Did you know it was 46 degrees Tuesday afternoon on Orcas Island but a whopping 55 degrees in Renton at the same time?

You know who doesn't care? Texas. Or Oklahoma.

The two states provided the battleground for winter and summer Tuesday afternoon as a monster cold front sliced the states in half, leaving the east side dealing with summertime heat while just a few hundred miles away, it was cold enough to snow.

How Mariners hitters will find Safeco Field feels 16° warmer

How Mariners hitters will find Safeco Field feels 16° warmer
Crews work to bring in the fences at Safeco Field. (Photo courtesy: Seattle Mariners)

It's a chilly April evening and fans bundle up as the temperature hovers around 55 degrees, but as Jesus Montero steps to the plate, that 55 will feel more like 71 degrees this year -- or maybe even warmer.

No, the Mariners didn't install a super heater in the stadium, but what they did do is move the fences in for the 2013 season.

Last year, I posted a blog asking the question if our chilly spring was an added factor in the team's offensive struggles. The conclusion was basically: not really, but I did find some interesting data on how cold weather affects home runs.

That got me to wondering this year: With the fences moved in, would that really lessen the impact of Seattle's typically cooler spring and summer climate in relation to the rest of the league?