tag:blogger.com,1999:blog-4572286363399496963.post540715665212454806..comments2024-03-27T04:17:21.221-08:00Comments on Deep Cold: Alaska Weather & Climate: Higher Resolution Howard Pass ModelingRickhttp://www.blogger.com/profile/03946704894714514716noreply@blogger.comBlogger14125tag:blogger.com,1999:blog-4572286363399496963.post-46124276035314650292014-03-08T19:58:46.441-09:002014-03-08T19:58:46.441-09:00The IR shot of that Brooks Range area I referenced...The IR shot of that Brooks Range area I referenced in an earlier topic has gone cold. Find that or similar and it may show what you're discussing.<br /><br />"http://pafg.arh.noaa.gov/arhdata/sat/hrpt/14046014547/4f1f.jpg<br /><br />0145 2/15 POES IR pass shows some wind and temp action NE of Feniak Lake in the vicinity of Howard Pass. Cold in the Colville River Basin, and relatively warmer in the Noatak from my understanding."<br /><br />Gary<br />NL7Yhttps://www.blogger.com/profile/15874712728971005352noreply@blogger.comtag:blogger.com,1999:blog-4572286363399496963.post-3831699920761339212014-03-07T14:10:11.870-09:002014-03-07T14:10:11.870-09:00Gary referenced satellite imagery and I am wonderi...Gary referenced satellite imagery and I am wondering if the imagery might be useful in identifying turbulent waves at or above mountain top level. It might strengthen the argument regarding downsloping, channeling, or gravity type waves.Climatologist49https://www.blogger.com/profile/04560505931210357679noreply@blogger.comtag:blogger.com,1999:blog-4572286363399496963.post-3351842322554935432014-03-06T10:18:48.332-09:002014-03-06T10:18:48.332-09:00Gary, I like the idea of working with UAF to obtai...Gary, I like the idea of working with UAF to obtain the necessary computing resources. I'll see if I can make a connection there.<br /><br />Concerning your earlier question about the factors causing the extreme winds: the computer model solves the equations of motion and thermodynamics for the atmosphere, so it will be able to tell us in as much detail as required what the physical causes were. But first we have to obtain a simulation that shows conditions comparable to those that were reported.<br />Richard Jameshttps://www.blogger.com/profile/08313902028896263276noreply@blogger.comtag:blogger.com,1999:blog-4572286363399496963.post-52605144731460111672014-03-05T20:12:52.014-09:002014-03-05T20:12:52.014-09:00I wonder if there's a way to present a visual ...I wonder if there's a way to present a visual cross section of the valley terrain through Howard Pass? As I recall it does climb in elevation from the Colville River then descends into the Noatak River. <br /><br />That feature, the terrestrial arch, has to have had a contributing effect along with the channeling effect of surrounding terrain. The Google Sat images of the lakes depict good wave action from NE winds.<br /><br />From an earlier post fly this through the Pass and visualize the terrain: http://gmap3d.com/?d=1403570&s=AK&f=gap<br /><br />GaryNL7Yhttps://www.blogger.com/profile/15874712728971005352noreply@blogger.comtag:blogger.com,1999:blog-4572286363399496963.post-28333682341193611562014-03-05T19:36:01.677-09:002014-03-05T19:36:01.677-09:00Somehow I missed Bethel and points southwest, and ...Somehow I missed Bethel and points southwest, and the Alaska Peninsula south of Becharof Lake. But that's not for a lack of trying in bad weather at the time. They're no longer on my list thanks to Google Earth.<br /><br />I think Brian you, Richard, and Eric (plus the NPS folks that work the Noatak and placed the monitors, and Rick and others at the NWS who support the project) have seen something special going on here. I'm suggesting there were unique conditions that might have created the extreme short lived weather phenomenon in Howard Pass.<br /><br />Surely the UAF Supercomputer or some other entity could be tasked to explore the factors. We have winds in Alaska that affect life. Learning why and where they develop would be worthy of investigation. <br /><br />It's a project in need of funding as a predictor of future events.<br /><br />GaryNL7Yhttps://www.blogger.com/profile/15874712728971005352noreply@blogger.comtag:blogger.com,1999:blog-4572286363399496963.post-11402733836958495912014-03-05T18:27:49.999-09:002014-03-05T18:27:49.999-09:00Where haven't you lived, visited, or flown thr...Where haven't you lived, visited, or flown through Gary? As always, it is a great to have your in-person perspective that is crucial to bridging the gap between data-only analysis and place-analysis. There are other types of downslope wind mechanisms that might also be in play othar than a Taku-type event. Thank you for giving this so much thought guys.Climatologist49https://www.blogger.com/profile/04560505931210357679noreply@blogger.comtag:blogger.com,1999:blog-4572286363399496963.post-22700089799363453022014-03-05T12:47:21.563-09:002014-03-05T12:47:21.563-09:00Eric, this is a good idea in principle - but to ru...Eric, this is a good idea in principle - but to run the model in a distributed fashion requires intensive communication between the nodes, so it wouldn't be practical for nodes in different locations. The problem is that each tile needs to communicate its boundary conditions with the neighboring tiles at every time step...<br /><br />A super-high-resolution simulation could probably be done in a few days on the amazon cloud using one of the higher performance options, e.g. 16 CPU cores, 30 GB of memory. Not a supercomputer, but not trivially inexpensive to use.<br />Richard Jameshttps://www.blogger.com/profile/08313902028896263276noreply@blogger.comtag:blogger.com,1999:blog-4572286363399496963.post-78993094647144000132014-03-05T12:40:30.991-09:002014-03-05T12:40:30.991-09:00I've wondered since the event's report wha...I've wondered since the event's report what differential conditions could have caused such extreme winds? <br /><br />No doubt Umiat to the NE was reporting the cold and some wind. There were likely pressure and temperature gradients through constrained terrain known for wind, and perhaps the winds aloft were brisk. The POES IR shot I offered earlier visibly portrayed winds in that location. <br /><br />Maybe (?) those factors were taken into account above. Perhaps describing what elements went into the analysis would be beneficial and offer an opportunity for learning. <br /><br />GaryNL7Yhttps://www.blogger.com/profile/15874712728971005352noreply@blogger.comtag:blogger.com,1999:blog-4572286363399496963.post-85237052387649428662014-03-05T12:37:15.630-09:002014-03-05T12:37:15.630-09:00Brian, it seems the same ingredients were present,...Brian, it seems the same ingredients were present, so the dynamics may have been the same. There was certainly a strong inversion near ridgeline and strong cross-barrier flow. It also appears that the flow was parallel to the ridge at about 500-600 mb, which is the third ingredient required for a Taku-type event.<br />Richard Jameshttps://www.blogger.com/profile/08313902028896263276noreply@blogger.comtag:blogger.com,1999:blog-4572286363399496963.post-33712213202580560982014-03-05T11:39:44.410-09:002014-03-05T11:39:44.410-09:00Yes the inversion at Howard Pass may have had an e...Yes the inversion at Howard Pass may have had an effect, but Juneau is in a very different location, topography wise. <br /><br />The nearby glacial ice fields, temperature and pressure contrasts, and steep gradient outflows contribute to the Taku events. Adjacent terrain focuses air flow through the Gastineau Channel next to town. <br /><br />I lived there for almost a year and walked from Douglas to downtown Juneau to work. I was a bitter environment in winter.<br /><br />Gary<br /><br /> NL7Yhttps://www.blogger.com/profile/15874712728971005352noreply@blogger.comtag:blogger.com,1999:blog-4572286363399496963.post-6808344764781181442014-03-05T11:32:39.270-09:002014-03-05T11:32:39.270-09:00Gary, Thanks for the remarks. I think there's...Gary, Thanks for the remarks. I think there's no doubt that air flowing through terrain constrictions can speed up in the manner you describe. It would be fun to have the modeling capacity to create a more reliable depiction of the processes at work.Richard Jameshttps://www.blogger.com/profile/08313902028896263276noreply@blogger.comtag:blogger.com,1999:blog-4572286363399496963.post-34787395135734947812014-03-05T07:55:56.936-09:002014-03-05T07:55:56.936-09:00What kind of resources would you need to do the hi...What kind of resources would you need to do the high res sim? There are many cheap, if not free, distributed computing options available (e.g. boinc). The only thing you would need is time, a way to distribute the proper code and any needed license. If the model can be parallelized on a supercomputer it might be "parallelized" on a distributed system.Eric Lundellhttps://www.blogger.com/profile/17914784378747801359noreply@blogger.comtag:blogger.com,1999:blog-4572286363399496963.post-69910686858375341972014-03-04T19:53:41.304-09:002014-03-04T19:53:41.304-09:00Wow, that is quite a comprehensive evaluation Rich...Wow, that is quite a comprehensive evaluation Richard. Thank you for going to the trouble of doing this. Based on your analysis, I am wondering if there might have been something similar to a "Taku" wind event that they get several times per winter in Juneau. In that instance, an inversion layer at, or just above, mountain top levels acts as a lid that prevents upward motion of air and if the large-scale synoptics are just right, a large pressure-gradient force squeezes the wind through the mountain gaps. Based on your model runs, that type of setup map have existed.<br />Climatologist49https://www.blogger.com/profile/04560505931210357679noreply@blogger.comtag:blogger.com,1999:blog-4572286363399496963.post-85780296217840300032014-03-04T19:30:50.995-09:002014-03-04T19:30:50.995-09:00This is certainly an important event, regardless o...This is certainly an important event, regardless of the actual values of reported temperatures and wind. Thank you Richard for the analyses. <br /><br />For those that may not have kept or can't readily access the reported values of potential interest:<br /><br />At 14/2/2014 3:39 pm AKST, Temp -42 f, Wind Chill -97 f, North 71G78 mph<br />At 15/2/2014 10:39 am AKST, Temp -37 f, Wind Chill -93 f, North 91G103 mph<br />At 16/2/2014 7:39 am AKST, Temp -40 f, Wind Chill -76 f, North 23G96 mph<br /><br />The anemometer failed to report after the last time interval.<br /><br />The reported winds are very strong, even for a pass surrounded by not particularly high rising terrain. Few main-continent Alaskan remote stations typically exceed 100 mph. The Aleutian Island chain would be an exception for example.<br /><br />In my experience flying in winds 50+ mph >2500 ft AGL , the closer to the ground one goes, the lower the wind speed and the greater the mechanical turbulence (the boundary layer versus laminar flow noted). <br /><br />The Howard Pass RAWS sits on a "hill" above surrounding terrain I believe from viewing that location via Google Earth 3-D. It's possible that terrain affects the velocity of air flowing over it, similar to the effect of an aircraft wing that increases the local relative velocity of air flowing over the wing (due to Bernoulli's principle), compared with air flowing below or along side of the structure's curvature (flatter ground in the case of Howard Pass?). <br /><br />I have no idea if nearby terrain or rock outcrops can affect the reported wind in certain directions at that location. <br /><br />GaryNL7Yhttps://www.blogger.com/profile/15874712728971005352noreply@blogger.com