The amazing weather of Mount Washington, NH

[Scott Dennstaedt, PhD]

How many places have you seen go from 1/8SM to 130SM within an hour...not all that uncommon if you are at the Mount Washington Observatory.  

KMWN 210353Z 29030KT 130SM FEW/// SKC M25/M37 RMK TPS LWR FEW DSNT SW
KMWN 210255Z 29033KT 1/8SM FZFG SCT000 M27/M27 RMK FZFG SCT000 VRY LGT ICG
 

[Hank]

"M27" is a very good reason for this Southern boy to stay far, far away until that brief period just after July 4th . . . 

Edited February 22, 2020 by Hank

[Tim Jodice]

Nantucket in the spring. It is the norm not an exception to go from 200 indefinite ceiling 1800RVR to VFR in 15-45 minutes 

[rbridges]

On 2/21/2020 at 5:24 PM, Scott Dennstaedt said:

How many places have you seen go from 1/8SM to 130SM within an hour...not all that uncommon if you are at the Mount Washington Observatory.  

KMWN 210353Z 29030KT 130SM FEW/// SKC M25/M37 RMK TPS LWR FEW DSNT SW
KMWN 210255Z 29033KT 1/8SM FZFG SCT000 M27/M27 RMK FZFG SCT000 VRY LGT ICG
 

I don't like to fly unless I have at least 120SM of visibility.  Gives me plenty of time to react.

[Ibra]

On 2/21/2020 at 10:24 PM, Scott Dennstaedt said:

How many places have you seen go from 1/8SM to 130SM within an hour..

(Joke) so visibility now flies at 110kts? that is nowhere near the speed of light nor the speed of wind 30kts 

I guess that increase has to do with how quickly the fog got heated rather then how it got mixed or lifted by the winds? 

Edited February 27, 2020 by Ibra

[Scott Dennstaedt, PhD]

18 hours ago, Ibra said:

I guess that increase has to do with how quickly the fog got heated rather then how it got mixed or lifted by the winds? 

This happened after sunset.  It was likely more about moisture advection.  Once that moisture source began to fade, so did the clouds.  When you get even a small drop in moisture in those higher wind scenarios, it can mix out pretty quickly.  

[Seymour]

[INA201]

We visited Mount Washington in August about ten years ago. It was 85F at the base and 45F at the summit and very windy. The elevation is not really all that high as well. It’s really a phenomenon. 

[Scott Dennstaedt, PhD]

KMWN 041452Z 27088G102KT 0SM -SHSN FZFG BLSN VV000 M09/M09 RMK PK WND 270116/09 LGT ICG

Visibility: 0 statute miles
Clouds: Indefinite ceiling 0 feet
Weather: Light snow showers and freezing fog with blowing snow
Wind speed: 88 knots
Wind direction: 270°
Wind gust: 102 knots
Temperature: -9°C
Dewpoint: -9°C

Thank goodness...only light icing today. 

Edited March 4, 2020 by Scott Dennstaedt

[Nick Pilotte]

Is that gust correct?  It looks a terrible day to even step out the door there. 

[Scott Dennstaedt, PhD]

Yep.  Very correct.  

[Ibra]

How come it does get get so much wind without level 5 tornado around?

[Scott Dennstaedt, PhD]

When it sticks up in the atmosphere at 6000 ft.  Think about winds at 6K when flying.  100 knots is not unusual at that altitude in the Northeast.  

[takair]

10 minutes ago, Scott Dennstaedt said:

When it sticks up in the atmosphere at 6000 ft.  Think about winds at 6K when flying.  100 knots is not unusual at that altitude in the Northeast.  

With all due respect, I think there is something more to it.  I think 100kts at 6k is rather rare for winds aloft here in CT and New Hampshire.  I think the local topology around Mount Washington causes some localized acceleration of the wind around and on top of Mt Washington.  Even right now, if you compare the average winds aloft vs surface winds at Mt Washington, the surface winds are roughly double the winds aloft not associated with the mountain.  

[carusoam]

Mt. Washington is known for hellacious winds...

It has world record wind speeds collected at the weather station...

231mph...

https://www.mountwashington.org/press-releases/mount-washington-world-record-wind-toppled/131/

Being the tallest mountain around... not sure what causes the records here... that didn’t exist for similar height mountains in other states...

I assumed the other states didn’t watch the weather as much as Mt. Washington does... 

Best regards,

-a-

[Ibra]

4 hours ago, carusoam said:

231mph...

M20K v1.0

9 hours ago, Scott Dennstaedt said:

When it sticks up in the atmosphere at 6000 ft.  Think about winds at 6K when flying.  100 knots is not unusual at that altitude in the Northeast.

Yes at high altitudes you can expect fast "horizontal winds" but I think there is something is peculiar with weather at Mt Washington that is maybe explained by surface pressure, airmass, topography? how does that look in long term t+10 day weather forecast for that place, does one ever see a similar data points like that funny METAR: 100kts & freezing fog? if YES then I guess it can be explained, if NO then it is simply an outlier, I was thinking most of it relate to steep "vertical winds" on that topography, this is hard to re-produce in forecast models and will be difficult to explain on flat synoptic surface pressure chart

But you are probably right maybe 200mph winds & freezing fog does regularly appears on synoptic pressure chart at 6000ft, just we don't someone standing up there all day along with weather instrumentation to tell us about it (only brave pilots who regularly fly non-turbo with 100kts wind in freezing IMC can confirm this )

[carusoam]

One of the geographic oddities of Mt. Washington....

The Great Lakes are to the west... a great supply of water, until the lakes freeze over...

Moist air traveling East towards the mountains + orographic lifting makes for a really unpleasant day of skiing... 

Another thing unique about Mt. Washington... it is really much taller, and Wider, than any of its neighbors...

Best regards,

-a-

[Scott Dennstaedt, PhD]

11 hours ago, Ibra said:

Yes at high altitudes you can expect fast "horizontal winds" but I think there is something is peculiar with weather at Mt Washington that is maybe explained by surface pressure, airmass, topography? how does that look in long term t+10 day weather forecast for that place, does one ever see a similar data points like that funny METAR: 100kts & freezing fog? if YES then I guess it can be explained, if NO then it is simply an outlier, I was thinking most of it relate to steep "vertical winds" on that topography, this is hard to re-produce in forecast models and will be difficult to explain on flat synoptic surface pressure chart

But you are probably right maybe 200mph winds & freezing fog does regularly appears on synoptic pressure chart at 6000ft, just we don't someone standing up there all day along with weather instrumentation to tell us about it (only brave pilots who regularly fly non-turbo with 100kts wind in freezing IMC can confirm this )

You should follow @MWObservatory on Twitter.  They post pretty frequently when winds start jumping up above 100 kts.  They even have "contests" to see if followers can guess the highest wind gusts.  

To answer your question, there's nothing special about Mount Washington here, pressure or otherwise.  If you had a sensor twenty or fifty miles at that elevation in any direction you'd see the same wind speeds.    

[Scott Dennstaedt, PhD]

16 hours ago, carusoam said:

Being the tallest mountain around... not sure what causes the records here... that didn’t exist for similar height mountains in other states...

I assumed the other states didn’t watch the weather as much as Mt. Washington does... 

 

It's the simple fact the Northeast U.S. and parts of Canada (Nova Scotia) tend to experience very intense "bomb" mid-latitude cyclones that don't happen out over the Rockies. With Mount Washington being up in elevation vs other lower elevation observation stations (airports), it records these high wind events.   

[takair]

Good description here including discussion on topography which does seem to indicate that topography plays into the winds. https://www.mountwashington.org/experience-the-weather/observer-comments.aspx?id=38387