isohume Posted July 31, 2011 Share Posted July 31, 2011 My question for you guys is...What implications could the SW drought have on the winter regarding strom tracks cutting into the great lakes? Could this be a player for the winter if the drought does not get busted. Thank you. Winter storm tracks across the CONUS are defined by global patterns and the manner in which quasi-stationary systems develop and set up like the ENSO/PNA/NAO, etc. The drought over the SW is not highly unusual for this time of year, since that region is at a desert latitude. The SW drought will not affect the flow and moisture transport off the Pacific nor the Gulf of Mexico this winter. Link to comment Share on other sites More sharing options...
am19psu Posted July 31, 2011 Author Share Posted July 31, 2011 The Advanced Dvorak Technique was designed to give objective guidance on TC intensity based on the orginal and subjective Dvorak Technique. The DT required a good amount of personal experience and time to gain reliable intensity estimates and could generally only be used in the later stages of a TC's development. The ADT uses computer sampling of a TC's cloud pattern and compares it to a statistical 10-year climatology before assigning a number. Unlike DT, the ADT can be applied in any stage of a TC's development. It has been found to be comparable in accuracy to the old DT employed by experienced forecatsers. However, just like any other guidance...the ADT is just another tool to help forecasters gain some measure of confidence when used and compared with other sources of guidance and real time data. It's overall accuracy is therefore subjective and depends on the scenario and forecaster utilizing it's output. The only thing I'll add is that the AMSU intensity estimates from CIMSS and CIRA appear to be more realistic than the ADT but are not available as often. Using all three at the same time with SATCON is even better yet. Link to comment Share on other sites More sharing options...
k*** Posted July 31, 2011 Share Posted July 31, 2011 The only thing I'll add is that the AMSU intensity estimates from CIMSS and CIRA appear to be more realistic than the ADT but are not available as often. Using all three at the same time with SATCON is even better yet. Except for yesterday Link to comment Share on other sites More sharing options...
tad Posted August 1, 2011 Share Posted August 1, 2011 I am looking for GFS Ensemble charts (500mb heights) for specific model cycles (dates and time) from last month going out the full 384 hours. Unfortunately, NCEP doesn't seem to provide more than 36 hours forward in their archives. I would very much appreciate any ideas as to where I might be able to obtain these. Thanks very much! Link to comment Share on other sites More sharing options...
ohleary Posted August 5, 2011 Share Posted August 5, 2011 I am looking for GFS Ensemble charts (500mb heights) for specific model cycles (dates and time) from last month going out the full 384 hours. Unfortunately, NCEP doesn't seem to provide more than 36 hours forward in their archives. I would very much appreciate any ideas as to where I might be able to obtain these. Thanks very much! What exactly are you looking for...500 mb charts of GFS ensemble products (spread/mean) or individual ensemble members? Either way, NCEP doesn't make charts available for much besides real-time data. Link to comment Share on other sites More sharing options...
tad Posted August 5, 2011 Share Posted August 5, 2011 Thanks for your reply! I am looking for the 500 mb ensemble spread/mean plots. You're right about NCEP as far as I can tell and I was wondering if there is some other source? What exactly are you looking for...500 mb charts of GFS ensemble products (spread/mean) or individual ensemble members? Either way, NCEP doesn't make charts available for much besides real-time data. Link to comment Share on other sites More sharing options...
Uncle Bobby Posted August 5, 2011 Share Posted August 5, 2011 I have 6 different bookmarks for archived data, 2 of which are pretty much just for radar data, and the last is for soundings. Have a look. You might find what you need. Either way, it's a nice little set of bookmarks to file away, IMO: http://vortex.plymouth.edu/u-make.html http://www.ncdc.noaa.gov/oa/mpp/freedata.html http://locust.mmm.ucar.edu/case-selection/ http://mesonet.agron.iastate.edu/GIS/apps/rview/warnings_cat.phtml?year=2007&wfo=ABQ&phenomena=SV&eventid=105&significance=W&warngeo=both http://hurricane.ncdc.noaa.gov/pls/plhas/has.dsselect http://weather.uwyo.edu/upperair/sounding.html Link to comment Share on other sites More sharing options...
SnowGoose69 Posted August 6, 2011 Share Posted August 6, 2011 There has definitely been an F4 spawned by a tropical system in its remnant stages...I believe it was bv whichever storm's record was broken 3-4 years back down in the Gulf states, some system in the 70s produced about 150 tornadoes as a remnant tropical and I'm sure one was an F4. Link to comment Share on other sites More sharing options...
ohleary Posted August 6, 2011 Share Posted August 6, 2011 Thanks for your reply! I am looking for the 500 mb ensemble spread/mean plots. You're right about NCEP as far as I can tell and I was wondering if there is some other source? Try here: http://cms.met.psu.edu/sref/ensembles/gefsp.html Link to comment Share on other sites More sharing options...
tad Posted August 10, 2011 Share Posted August 10, 2011 ohleary, This is just what I needed! My deepest thanks! Link to comment Share on other sites More sharing options...
tad Posted August 10, 2011 Share Posted August 10, 2011 Uncle Bobby, These bookmarks are terrific, and I very much appreciate your sharing them, but unfortunately I wasn't able to find what I was seeking (as you suspected). TAD Link to comment Share on other sites More sharing options...
metalicwx366 Posted August 15, 2011 Share Posted August 15, 2011 Thursday, We had a Severe Thundestorm warned line of storms move through here. The winds were very strong coming from the west. Then the winds calmed down and it was just heavy rain and significant lightning. Then a few minutes later the winds got very strong again and this time came from the east. What was the windshift a result of? Link to comment Share on other sites More sharing options...
isohume Posted August 15, 2011 Share Posted August 15, 2011 Thursday, We had a Severe Thundestorm warned line of storms move through here. The winds were very strong coming from the west. Then the winds calmed down and it was just heavy rain and significant lightning. Then a few minutes later the winds got very strong again and this time came from the east. What was the windshift a result of? It was most likely the outflow on the backside of the storm...or an outflow from a nearby storm. Link to comment Share on other sites More sharing options...
dolebot_broward_nw Posted August 16, 2011 Share Posted August 16, 2011 A lot of folks have been pointing at the south central US ridge (Texas Death Ridge) as a reason why no storms have formed near the Gulf of Mexico. Pardon my noobness, but where might I find an analysis or model that clearly depicts this feature? Link to comment Share on other sites More sharing options...
ohleary Posted August 16, 2011 Share Posted August 16, 2011 A lot of folks have been pointing at the south central US ridge (Texas Death Ridge) as a reason why no storms have formed near the Gulf of Mexico. Pardon my noobness, but where might I find an analysis or model that clearly depicts this feature? Link to comment Share on other sites More sharing options...
tornadotony Posted August 16, 2011 Share Posted August 16, 2011 There has definitely been an F4 spawned by a tropical system in its remnant stages...I believe it was bv whichever storm's record was broken 3-4 years back down in the Gulf states, some system in the 70s produced about 150 tornadoes as a remnant tropical and I'm sure one was an F4. Carla 1961 produced an F4 on Galveston Island. I believe there was another one back in the '60s or '70s but I'm not positive. None of the 2004/2005 or 2008 hurricanes spawned an F4/EF4. Link to comment Share on other sites More sharing options...
marino13882 Posted August 21, 2011 Share Posted August 21, 2011 I've got a question, it may be very basic but something I have wanted to know for a while. How does the eye of the Hurricane come about? Link to comment Share on other sites More sharing options...
isohume Posted August 21, 2011 Share Posted August 21, 2011 I've got a question, it may be very basic but something I have wanted to know for a while. How does the eye of the Hurricane come about? When convection around a TC's center becomes strong enough and maintained by high SSTs and latent heat release, etc...the rising motions within the convective bands diverge as they reach the tropopause. This, in turn, creates and maintains an anticyclone over the storm, which itself generates strong downward motion or "subsidence" into the TC's center. This downward motion compresses and warms the air and develops a very strong inversion about one mile above the ocean sfc. Thus, no clouds are able to form except those below the inversion which are normally short lived, dependent on moisture mixed in from the eyewall. This is a positive feedback mechanism as the divergent flow aloft maintains continuous and strong convective flow...while the strength of convection maintains and defines the upper anticyclone. Link to comment Share on other sites More sharing options...
usedtobe Posted August 21, 2011 Share Posted August 21, 2011 I've got a question, it may be very basic but something I have wanted to know for a while. How does the eye of the Hurricane come about? Here's a little different explanation than mentioned by isohume. It also shows the structure of a hurricane once it develops and eye. http://www.ems.psu.edu/~nese/ch11sec3.htm Link to comment Share on other sites More sharing options...
isohume Posted August 21, 2011 Share Posted August 21, 2011 Here's a little different explanation than mentioned by isohume. It also shows the structure of a hurricane once it develops and eye. http://www.ems.psu.e...se/ch11sec3.htm Haha yeah, I was trying to keep it simple. I guess I should have linked to a white paper. Link to comment Share on other sites More sharing options...
marino13882 Posted August 21, 2011 Share Posted August 21, 2011 Haha yeah, I was trying to keep it simple. I guess I should have linked to a white paper. Thanks guys Link to comment Share on other sites More sharing options...
Wannabehippie Posted August 22, 2011 Share Posted August 22, 2011 Here is a question for a pro met Why do tropical systems undergo diurnal strengthening and weakening? Thanks guys Link to comment Share on other sites More sharing options...
wkd Posted August 22, 2011 Share Posted August 22, 2011 Asked this yesterday in the Irene thread but no response. At what latitude and/or forward speed does the coreolis effect have a signifant influence on the path of a tropical cyclone? Link to comment Share on other sites More sharing options...
phil882 Posted August 22, 2011 Share Posted August 22, 2011 Here is a question for a pro met Why do tropical systems undergo diurnal strengthening and weakening? There is a distinct diurnal convective cycle, caused mainly by the fact that Sea Surface Temperatures don't decrease substantially at night, thus the atmospheric profile over oceans becomes more unstable during the night. However the effect is not very strong, and tropical cyclone strengthening and weakening occurs at all times during the day and its not diurnaly driven in most cases. Asked this yesterday in the Irene thread but no response. At what latitude and/or forward speed does the coreolis effect have a signifant influence on the path of a tropical cyclone? The effect of the Coriolis effect increases the further in latitude you go, in either direction from the equator by definition 2*Omega*Sin(Phi) The Omega is the Coriolis parameter which is a constant. The Phi is the actual given latitude of a location. Multiply everything together will give you the planetary vorticity, or the effect that the Coriolis effect has on rotation. Obviously when you are at the equator the effect is zero, but increases in either direction in magnitude (its negative in the Southern Hemisphere) As for actually answering your question, I'm not sure if there is a given threshold value that proclaims that the Coriolis effect has a large enough effect to cause "significant influence" on the path of a TC, although it is the primary reason why you see TCs re-curve in oceanic basins where tropical cyclone tracks march into the subtropics. However, you might be familiar with the BAM track guidance suite... these models are based on the Beta Plane approximation, which accounts for the effect that the Coriolis effect has on tropical cyclones. If you are fond of trigonometry and calculus based math, you might want to try tackling the following paper below to increase your understanding of the Beta Plane Approximation or Beta Effect below. http://people.maths....s/BetaPlane.pdf Hope this helps! Link to comment Share on other sites More sharing options...
ohleary Posted August 22, 2011 Share Posted August 22, 2011 There is a distinct diurnal convective cycle, caused mainly by the fact the Sea Surface Temperatures don't degrees at night, thus the atmospheric profile over oceans becomes more unstable during the night. However the effect is not very strong, and tropical cyclone strengthening and weakening occurs at all times during the day and its not diurnaly driven in most cases. The effect of the Coriolis effect increases the further in latitude you go, in either direction from the equator by definition 2*Omega*Phi The Omega is the Coriolis parameter which is a constant. The Phi is the actual given latitude of a location. Multiply everything together will give you the planetary vorticity, or the effect that the Coriolis effect has on rotation. Obviously when you are at the equator the effect is zero, but increases in either direction in magnitude (its negative in the Southern Hemisphere) As for actually answering your question, I'm not sure if there is a given threshold value that proclaims that the Coriolis effect has a large enough effect to cause "significant influence" on the path of a TC, although it is the primary reason why you see TCs re-curve in oceanic basins where tropical cyclone tracks march into the subtropics. However, you might be familiar with the BAM track guidance suite... these models are based on the Beta Plane approximation, which accounts for the effect that the Coriolis effect has on tropical cyclones. If you are fond of trigonometry and calculus based math, you might want to try tacking the following paper below to increase your understanding of the Beta Plane Approximation or Beta Effect below. http://people.maths....s/BetaPlane.pdf Hope this helps! I think you're missing a couple of elements in your Coriolis equation Looking at historical hurricane paths I'd say a good guideline is 10 degrees north/south...there have been a few tropical storms that have formed closer to the equator but the overwhelming majority have formed north of 10 and south of 10. http://www.csc.noaa.gov/hurricanes/# Click on hurricanes and they'll all be there! Link to comment Share on other sites More sharing options...
Wannabehippie Posted August 22, 2011 Share Posted August 22, 2011 I think there is a word or two missing there. There is a distinct diurnal convective cycle, caused mainly by the fact the Sea Surface Temperatures don't degrees at night, thus the atmospheric profile over oceans becomes more unstable during the night. However the effect is not very strong, and tropical cyclone strengthening and weakening occurs at all times during the day and its not diurnaly driven in most cases. The effect of the Coriolis effect increases the further in latitude you go, in either direction from the equator by definition 2*Omega*Phi The Omega is the Coriolis parameter which is a constant. The Phi is the actual given latitude of a location. Multiply everything together will give you the planetary vorticity, or the effect that the Coriolis effect has on rotation. Obviously when you are at the equator the effect is zero, but increases in either direction in magnitude (its negative in the Southern Hemisphere) As for actually answering your question, I'm not sure if there is a given threshold value that proclaims that the Coriolis effect has a large enough effect to cause "significant influence" on the path of a TC, although it is the primary reason why you see TCs re-curve in oceanic basins where tropical cyclone tracks march into the subtropics. However, you might be familiar with the BAM track guidance suite... these models are based on the Beta Plane approximation, which accounts for the effect that the Coriolis effect has on tropical cyclones. If you are fond of trigonometry and calculus based math, you might want to try tacking the following paper below to increase your understanding of the Beta Plane Approximation or Beta Effect below. http://people.maths....s/BetaPlane.pdf Hope this helps! Link to comment Share on other sites More sharing options...
phil882 Posted August 22, 2011 Share Posted August 22, 2011 I think you're missing a couple of elements in your Coriolis equation Looking at historical hurricane paths I'd say a good guideline is 10 degrees north/south...there have been a few tropical storms that have formed closer to the equator but the overwhelming majority have formed north of 10 and south of 10. http://www.csc.noaa.gov/hurricanes/# Click on hurricanes and they'll all be there! Whoops... forgot to put the sine function for the planetary vorticity equation... thanks! Also fixed the wording of the first reply. I guess I have a case of the Monday's Link to comment Share on other sites More sharing options...
Wannabehippie Posted August 22, 2011 Share Posted August 22, 2011 Yeah **** mondays! Whoops... forgot to put the sine function for the planetary vorticity equation... thanks! Also fixed the wording of the first reply. I guess I have a case of the Monday's Link to comment Share on other sites More sharing options...
wx.1028 Posted August 22, 2011 Share Posted August 22, 2011 ive been reading the hurricane threads recently, and i noticed the term "pouch" being tossed around alot. what exactly does this mean? Link to comment Share on other sites More sharing options...
am19psu Posted August 22, 2011 Author Share Posted August 22, 2011 ive been reading the hurricane threads recently, and i noticed the term "pouch" being tossed around alot. what exactly does this mean? Here is an overview with some links... ask after Irene and I can give a better answer. http://met.nps.edu/~mtmontgo/marsupial.html Link to comment Share on other sites More sharing options...
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