WhiteoutWX Posted July 31, 2011 Share Posted July 31, 2011 The overall structure looks fine to me, good cyclonic curvature. Just lacking some deep convection at the moment. Link to comment Share on other sites More sharing options...
am19psu Posted July 31, 2011 Share Posted July 31, 2011 Nick, on my phone so sorry for quality... NAO is kinda chicken and egg... the storm can have a definite effect in its status... I don't think you can just look at NAO progs and make a forecast off it because of the connection to the storm itself Link to comment Share on other sites More sharing options...
My Weather Today Posted July 31, 2011 Share Posted July 31, 2011 Nick, on my phone so sorry for quality... NAO is kinda chicken and egg... the storm can have a definite effect in its status... I don't think you can just look at NAO progs and make a forecast off it because of the connection to the storm itself Can you explain this reasoning in more details? I think I know what you're trying to say, but I want to make sure I'm following you correctly. Link to comment Share on other sites More sharing options...
EasternUSWX Posted July 31, 2011 Share Posted July 31, 2011 Couple areas of new convection firing up in there. Might make a run at it later tonight. Link to comment Share on other sites More sharing options...
am19psu Posted July 31, 2011 Share Posted July 31, 2011 Just that the future cyclone can have a direct effect on NAO state through latent heat release... not to mention other things like pacific convection and mountain torques that are not handled well by the models... I wouldn't use an NAO prog as a basis for my forecast verbatim Link to comment Share on other sites More sharing options...
My Weather Today Posted July 31, 2011 Share Posted July 31, 2011 Just that the future cyclone can have a direct effect on NAO state through latent heat release... not to mention other things like pacific convection and mountain torques that are not handled well by the models... I wouldn't use an NAO prog as a basis for my forecast verbatim OK, I thought that's what you were implying I just wanted to make sure. Link to comment Share on other sites More sharing options...
OSUmetstud Posted July 31, 2011 Share Posted July 31, 2011 Nick, on my phone so sorry for quality... NAO is kinda chicken and egg... the storm can have a definite effect in its status... I don't think you can just look at NAO progs and make a forecast off it because of the connection to the storm itself I wasn't necessarily just using the NAO value for the forecast anyway. I was looking at the height anomalies of both the GFS and the Euro and their ensembles which showed a -NAO type pattern (Davis Strait Blocking with low height anomalies over the US East Coast and into the Western Atlantic). That particular pattern does not look favorable for me to get a storm to the US East Coast if it's relatively strong north of the Antilles. Wouldn't the storm have more of an effect on the NAO during and after recurvature, not before? Link to comment Share on other sites More sharing options...
My Weather Today Posted July 31, 2011 Share Posted July 31, 2011 It will be interesting to read some of the forecast discussions coming out of this WFO over the next few days. AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE SAN JUAN PR 1040 PM AST SAT JUL 30 2011 UPDATE...MAIN ATTENTION IS A TROPICAL WAVE NEAR 750 MILES EAST OF THE LESSER ANTILLES. A TROPICAL DEPRESSION COULD FORM SUNDAY. THIS SYSTEM IS MOVING TOWARD THE WEST-NORTHWEST AT 15 TO 20 MPH AND HAS A HIGH CHANCE...90 PERCENT...OF BECOMING A TROPICAL CYCLONE DURING THE NEXT 48 HOURS. AN AIR FORCE PLANE IS SCHEDULED TO INVESTIGATE THIS DISTURBANCE SUNDAY AFTERNOON. PLEASE STAY TUNED FOR FURTHER INFORMATION ON THIS SYSTEM. Link to comment Share on other sites More sharing options...
EasternUSWX Posted July 31, 2011 Share Posted July 31, 2011 The convection is increasing around center and looks like it will continue. Just looks a mess right now though. By morning probably will look half decent. Link to comment Share on other sites More sharing options...
Ellinwood Posted July 31, 2011 Share Posted July 31, 2011 The convection is increasing around center and looks like it will continue. Just looks a mess right now though. By morning probably will look half decent. Why? Link to comment Share on other sites More sharing options...
EasternUSWX Posted July 31, 2011 Share Posted July 31, 2011 Why? Dmax. Link to comment Share on other sites More sharing options...
Ellinwood Posted July 31, 2011 Share Posted July 31, 2011 Dmax. That all you got? Link to comment Share on other sites More sharing options...
Superstorm93 Posted July 31, 2011 Share Posted July 31, 2011 ^^ Not saying anything Link to comment Share on other sites More sharing options...
EasternUSWX Posted July 31, 2011 Share Posted July 31, 2011 That all you got? It's really the only thing going for 91L right now and why we usually see flare ups in convection in weak tropical disturbances. Shear is around 5-10KTS, and it's still in a pretty dry air but, it's slowly working its way out of that. Should be in less shear and more moist environment in the next 24-36hrs. Link to comment Share on other sites More sharing options...
TUweathermanDD Posted July 31, 2011 Share Posted July 31, 2011 It's really the only thing going for 91L right now and why we usually see flare ups in convection in weak tropical disturbances. Shear is around 5-10KTS, and it's still in a pretty dry air but, it's slowly working its way out of that. Should be in less shear and more moist environment in the next 24-36hrs. While I would indeed attribute the flare up in convection to the diurnal maximum, I should note 5-10 kts of shear just isn't all that much. The environment will be better in 24-36hrs for sure, but it's not all that bad at this point. The system really simply needs to consolidate around the low pressure center, and soon it will enter that pocket of moist air, a la 12-18hrs. Not really all about the dmin and max, though that is a notable entity for non fully developed tropical cyclones. Link to comment Share on other sites More sharing options...
EasternUSWX Posted July 31, 2011 Share Posted July 31, 2011 1. SATELLITE IMAGES AND BUOY DATA INDICATE THAT THE LARGE LOW PRESSURESYSTEM CENTERED ABOUT 675 MILES EAST OF THE LESSER ANTILLES ISCONTINUING TO BECOME BETTER ORGANIZED...AND IT COULD BE CLOSE TOBECOMING A TROPICAL DEPRESSION. THIS SYSTEM HAS A HIGH CHANCE...NEAR 100 PERCENT...OF BECOMING A TROPICAL CYCLONE DURING THE NEXT48 HOURS AS IT MOVES WEST-NORTHWESTWARD NEAR 15 MPH. TROPICALCYCLONE WATCHES OR WARNINGS WOULD LIKELY BE REQUIRED FOR PARTS OFTHE LESSER ANTILLES IF THE LOW BECOMES A TROPICAL CYCLONE LATERTODAY...AND INTERESTS IN THESE AREAS SHOULD CLOSELY MONITOR THEPROGRESS OF THIS SYSTEM. AN AIR FORCE HURRICANE HUNTER AIRCRAFT ISSCHEDULED TO INVESTIGATE THIS DISTURBANCE LATER THIS AFTERNOON. Link to comment Share on other sites More sharing options...
OHweather Posted July 31, 2011 Share Posted July 31, 2011 I like the upper level winds on top of this thing. Clear divergent pattern, with favorable outflow both to the north and south, as upper level winds rush away from the system: Shear continues to decrease ahead of 91L, as the upper level anti-cyclone its under continues to slide west: There is a good bit of mid level dry air to the north of 91L. While this may slow things somewhat, the system's large size and relativly weak shear it will be under in the short term should keep dry air from killing the system. The 12z Euro shows the dry air slowly weakening over the coming days, with no mid level humidities below 30% near the system by Monday morning as it approaches the Antilles: The vorticity centers are well stacked and we already have a well defined surface circulation per traditional satellite loops and microwave images. Convection has been scattered (likely due to the dry air) but one good concentrated burst near the center will likely cause the NHC to initiate advisories based on the near 100% prob assessed in the 2am TWO, so this will likely develop at given time. Right now I think this takes until Tuesday or Wednesday to possibly become a hurricane, given the large size and possible trouble the system will have with dry air, although gradual organization/intensification will likely continue through that time given an upper level anti-cyclone over the system and a gradual decrease in dry air around the system. The 0z GFS appears to indicate a quite large and powerfull poleword outflow channel as 91L approached Puerto Rico Wednesday evening, a sign of a possibly deep, strong, and large tropical cyclone by this point: If this is the case, the pattern that has dominated all summer and that is expected to still be in place through the medium range suggests that a curve out to sea becomes the favored solution. While things can change I guess, we will need to see a pretty major shift in height anomalies across the western-northern hemisphere pretty fast. A -PNA/-NAO, which have more or less been in place the past two months, do not favor a ridge over the western Atlantic, resulting in many a re-curve. June 1-July 24th: Vs. the day 6-10 12z Euro ensemble mean height anomaly: Just some food for thought at this point I suppose. Link to comment Share on other sites More sharing options...
stormtracker Posted July 31, 2011 Share Posted July 31, 2011 LOlzationage You, eastern and superstorm have got to bring more than this to the table, starting to get complaints about you guys. Step it up fellas or do like I do....lurk. This could go for a few more of yall too. If you don't know much or have useless info and cut and pastes...shhhhh. shhhh. Watch and learn. I'm a tropical dummy..so I simply lurk. Try it. PM me if you have questions, comments. Link to comment Share on other sites More sharing options...
GaWx Posted July 31, 2011 Share Posted July 31, 2011 Are you just looking at the CPC monthly mean? I took a look at that awhile back and the signal is quite weak. I think this is because hurricanes travel in that area for a few days time so you won't see much of a signal in a monthly mean. No, I'm looking at the dailies that go back to 1950: ftp://ftp.cpc.ncep.n...1.current.ascii I looked at the 26 east coast direct hurricane hits (including FL) from 1950 through 2010 that weren't storms that just pretty much grazed the east coast. I counted 19 (72%) with a +NAO and only 7 (28%) with a -NAO on the day of hitting. Three had >+1, seven had +0.5 to +1, nine had 0 to +0.5, four had 0 to -0.5, three had -0.5 to -1, and none had less than -1. The lowest was -0.965 (Hazel of 1954). The avg. and median NAO was ~+0.3. OTOH, The nine grazers averaged near zero with a -1.359 lowest NAO. So, there clearly seems to be a partial positive correlation of NAO and nongrazing east coast hurricane hits, which makes sense when one considers the tendencies of the overall pattern in the western Atlantic/east coast during a -NAO vs. a +NAO. This all tells me that getting a nongrazing east coast hit from 91L with the projected ~-2 NAO will be very difficult. Even getting a graze wil be pretty hard. Link to comment Share on other sites More sharing options...
Superstorm93 Posted July 31, 2011 Share Posted July 31, 2011 6z suite has updated The OFCI track was released by the NHC. Should be one of the more interesting discussions of the year (so far) when the first package comes out Link to comment Share on other sites More sharing options...
CooL Posted July 31, 2011 Share Posted July 31, 2011 http://moe.met.fsu.edu/cgi-bin/gfdltc2.cgi?time=2011073100-invest91l&field=Sea+Level+Pressure&hour=Animation 00z GFDL. Looks like it misses the trough and stays south. take with a grain of salt, the system hasnt even formed yet. Link to comment Share on other sites More sharing options...
phil882 Posted July 31, 2011 Share Posted July 31, 2011 http://philstropical...-the-caribbean/ Here are my morning thoughts on Invest 91L. My general thinking is that we should see a continued WNW track for now, but ultimately this storm will have to turn NW and N in the face of a pretty significant upper level trough. There has been some discussion on if the +SOI could help influence the strength of the subtropical high and keep the system on a more westerly course due to an underestimated ridge. However, I feel that impact of the -NAO will have a stronger impact asit is expected to tank over the new few days, which should force any mid-latitude upper level disturbance to amplify over the Atlantic ocean at a low enough latitude to erode the subtropical ridge enough for re-curvature. The current ridge over Greenland is rather impressive representing an omega block that is forecasted to persist. Link to comment Share on other sites More sharing options...
phil882 Posted July 31, 2011 Share Posted July 31, 2011 A recent microwave pass also confirms that the low level circulation is getting better defined and more co-located with the convection recently blossoming. I think TCG is going to occur before the morning is out. Link to comment Share on other sites More sharing options...
Srain Posted July 31, 2011 Author Share Posted July 31, 2011 Until 91L slows its forward motion, development will remain rather slow, IMO. 15-20 WNW movement isn't going to allow for any rapid intensification. My hunch is RECON will confirm that dry air is still within the mid levels and therefore TD status will likely be the most we'll see until 91L slows down its forward motion. I also suspect that any future Emily would be a bigger concern once it enters the Caribbean Sea. The threat to PR and more so to Hispaniola, are the bigger concerns at the moment in the days ahead. We will see. Link to comment Share on other sites More sharing options...
Floydbuster Posted July 31, 2011 Share Posted July 31, 2011 6z suite has updated The OFCI track was released by the NHC. Should be one of the more interesting discussions of the year (so far) when the first package comes out That would be a really close call for the Southeast coast. Link to comment Share on other sites More sharing options...
Srain Posted July 31, 2011 Author Share Posted July 31, 2011 The OFCI track was released by the NHC. Picking out one model track and running with it offers no useful discussion to the thread. I'm sure the 5 's at extremewx appreciate the spam, though... Link to comment Share on other sites More sharing options...
Floydbuster Posted July 31, 2011 Share Posted July 31, 2011 000 ABNT20 KNHC 311142 TWOAT TROPICAL WEATHER OUTLOOK NWS NATIONAL HURRICANE CENTER MIAMI FL 800 AM EDT SUN JUL 31 2011 FOR THE NORTH ATLANTIC...CARIBBEAN SEA AND THE GULF OF MEXICO... SATELLITE IMAGES AND NOAA BUOY DATA INDICATE THAT THE LARGE AND ELONGATED LOW PRESSURE SYSTEM CENTERED ABOUT 650 MILES EAST OF THE NORTHERN WINDWARD ISLANDS CONTINUES TO BECOME BETTER ORGANIZED...AND IT COULD DEVELOP INTO A TROPICAL DEPRESSION AT ANY TIME. THIS SYSTEM HAS A HIGH CHANCE...NEAR 100 PERCENT...OF BECOMING A TROPICAL CYCLONE DURING THE NEXT 24 TO 48 HOURS AS IT MOVES WEST-NORTHWESTWARD NEAR 15 MPH. IF THE LOW BECOMES A TROPICAL CYCLONE LATER TODAY...TROPICAL STORM WATCHES OR WARNINGS WOULD LIKELY BE REQUIRED FOR PORTIONS OF THE NORTHERN WINDWARD ISLANDS AND THE LEEWARD ISLANDS. INTERESTS IN THESE AREAS SHOULD CLOSELY MONITOR THE PROGRESS OF THIS SYSTEM. AN AIR FORCE RESERVE UNIT RECONNAISSANCE AIRCRAFT IS SCHEDULED TO INVESTIGATE THIS DISTURBANCE LATER THIS AFTERNOON. ELSEWHERE...TROPICAL CYCLONE FORMATION IS NOT EXPECTED DURING THE NEXT 48 HOURS. FORECASTER STEWART Link to comment Share on other sites More sharing options...
David Reimer Posted July 31, 2011 Share Posted July 31, 2011 000 ABNT20 KNHC 311142 TWOAT TROPICAL WEATHER OUTLOOK NWS NATIONAL HURRICANE CENTER MIAMI FL 800 AM EDT SUN JUL 31 2011 FOR THE NORTH ATLANTIC...CARIBBEAN SEA AND THE GULF OF MEXICO... SATELLITE IMAGES AND NOAA BUOY DATA INDICATE THAT THE LARGE AND ELONGATED LOW PRESSURE SYSTEM CENTERED ABOUT 650 MILES EAST OF THE NORTHERN WINDWARD ISLANDS CONTINUES TO BECOME BETTER ORGANIZED...AND IT COULD DEVELOP INTO A TROPICAL DEPRESSION AT ANY TIME. THIS SYSTEM HAS A HIGH CHANCE...NEAR 100 PERCENT...OF BECOMING A TROPICAL CYCLONE DURING THE NEXT 24 TO 48 HOURS AS IT MOVES WEST-NORTHWESTWARD NEAR 15 MPH. IF THE LOW BECOMES A TROPICAL CYCLONE LATER TODAY...TROPICAL STORM WATCHES OR WARNINGS WOULD LIKELY BE REQUIRED FOR PORTIONS OF THE NORTHERN WINDWARD ISLANDS AND THE LEEWARD ISLANDS. INTERESTS IN THESE AREAS SHOULD CLOSELY MONITOR THE PROGRESS OF THIS SYSTEM. AN AIR FORCE RESERVE UNIT RECONNAISSANCE AIRCRAFT IS SCHEDULED TO INVESTIGATE THIS DISTURBANCE LATER THIS AFTERNOON. ELSEWHERE...TROPICAL CYCLONE FORMATION IS NOT EXPECTED DURING THE NEXT 48 HOURS. FORECASTER STEWART Just a tad bit easier to read. Link to comment Share on other sites More sharing options...
OSUmetstud Posted July 31, 2011 Share Posted July 31, 2011 No, I'm looking at the dailies that go back to 1950: ftp://ftp.cpc.ncep.n...1.current.ascii I looked at the 25 east coast direct hurricane hits (including FL) from 1950 through 2010 that weren't storms that just pretty much grazed the east coast. I counted 18 (72%) with a +NAO and only 7 (28%) with a -NAO on the day of hitting. Three had >+1, seven had +0.5 to +1, eight had 0 to +0.5, four had 0 to -0.5, three had -0.5 to -1, and none had less than -1. The lowest was -0.965 (Hazel of 1954). The avg. and median NAO was ~+0.3. OTOH, The nine grazers averaged near zero with a -1.359 lowest NAO. So, there clearly seems to be a partial positive correlation of NAO and nongrazing east coast hurricane hits, which makes sense when one considers the tendencies of the overall pattern in the western Atlantic/east coast during a -NAO vs. a +NAO. This all tells me that getting a nongrazing east coast hit from 91L with the projected ~-2 NAO will be very difficult. Even getting a graze wil be pretty hard. wow...thanks...I've been looking for the daily data. The only research in papers I could find had to do with monthlies and TCs. Link to comment Share on other sites More sharing options...
#NoPoles Posted July 31, 2011 Share Posted July 31, 2011 Until 91L slows its forward motion, development will remain rather slow, IMO. 15-20 WNW movement isn't going to allow for any rapid intensification. My hunch is RECON will confirm that dry air is still within the mid levels and therefore TD status will likely be the most we'll see until 91L slows down its forward motion. I also suspect that any future Emily would be a bigger concern once it enters the Caribbean Sea. The threat to PR and more so to Hispaniola, are the bigger concerns at the moment in the days ahead. We will see. Can you say, SAL??? Link to comment Share on other sites More sharing options...
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