jrips27 Posted August 2, 2011 Share Posted August 2, 2011 WTNT35 KNHC 021805 TCPAT5 BULLETIN TROPICAL STORM EMILY INTERMEDIATE ADVISORY NUMBER 4A NWS NATIONAL HURRICANE CENTER MIAMI FL AL052011 200 PM AST TUE AUG 02 2011 ...EMILY BACK ON TRACK... SUMMARY OF 200 PM AST...1800 UTC...INFORMATION ---------------------------------------------- LOCATION...15.6N 64.8W ABOUT 215 MI...345 KM SSE OF SAN JUAN PUERTO RICO MAXIMUM SUSTAINED WINDS...45 MPH...70 KM/H PRESENT MOVEMENT...W OR 280 DEGREES AT 12 MPH...19 KM/H MINIMUM CENTRAL PRESSURE...1006 MB...29.71 INCHES WATCHES AND WARNINGS -------------------- CHANGES WITH THIS ADVISORY... NONE. am19psu EDIT: fixed the formatting Link to comment Share on other sites More sharing options...
Bryan Wood Posted August 2, 2011 Share Posted August 2, 2011 Good thing I only have to send one forecast a day. I think I'd have amended my forecast about 3 different times in the last 3 hours if I was actually operational. I hear you on that. I send out my forecast once a day around 9 am. Today, I presented 5 possible scenarios with various (mostly low) degrees of confidence. Indirectly, I said I have no idea what's going to happen, but here's the one that looks most plausible. Emily is incredibly temperamental...but what else would we expect for a developing cyclone in the eastern Caribbean? Link to comment Share on other sites More sharing options...
toad strangler Posted August 2, 2011 Share Posted August 2, 2011 12mph W? Link to comment Share on other sites More sharing options...
am19psu Posted August 2, 2011 Share Posted August 2, 2011 Odd, I could've sworn that just moments ago I posted this... Ah well; here goes again. I think this storm is about to rapidly intensify. And if you post it again, you will be 5-posted. Link to comment Share on other sites More sharing options...
wxmx Posted August 2, 2011 Share Posted August 2, 2011 Elongated and on the western edge of the convection.... yawn. Link to comment Share on other sites More sharing options...
PSUBlizzicane2007 Posted August 2, 2011 Share Posted August 2, 2011 I'd probably go with something around steady-state around 35-40 kt, with some short-term fluctuations typical of sheared storms. Despite the impressive wind readings and the lower pressure on the current pass, I'm still not convinced this is a long-term intensification. It's certainly within the realm of possibility that it is, but then again we've been fooled by this before. I don't think this will die before Hispaniola though. I'm much more convinced than yesterday that this is on the path to intensification... at least today, the storm has reorganized a center under some deep convection with improving outflow. Still not great radar presentation, but much more impressive than the hot mess it was yesterday. 12Z Euro is looking interesting, crashing Emily into the DR/Haiti border. Not sure what will happen after yet. Link to comment Share on other sites More sharing options...
icebreaker5221 Posted August 2, 2011 Share Posted August 2, 2011 12Z GFS assimilation cycle appears to have done a respectable job with the local environment. We can see in a comparison of the Santo Domingo 12Z sounding to the GFS analysis (courtesy TwisterData) that the incredibly dry air at 600 and 400 mb is captured, as is the surface-200 mb 10-15 kts shear. Therefore, I would give credence to the GFS forecast over the short term. That said, the vortex relocation from south to north of Hispanola from 42-54 h, while possible, still looks a bit suspicious/awkward to me. Link to comment Share on other sites More sharing options...
Riptide Posted August 2, 2011 Share Posted August 2, 2011 Rapid-Scan loop http://wwwghcc.msfc....s=10&map=latlon You can see the center on the NW edge of the convection but it appears to be rotating around another center? EDIT: It appears to simply be elongated. Link to comment Share on other sites More sharing options...
wxmx Posted August 2, 2011 Share Posted August 2, 2011 Link to comment Share on other sites More sharing options...
kab2791 Posted August 2, 2011 Share Posted August 2, 2011 12Z HWRF/GFDL both develop Emily into a hurricane down the road after land interaction, as the GFS alluded to. The 12Z Euro remains more or less an open wave. Link to comment Share on other sites More sharing options...
Uncle Bobby Posted August 2, 2011 Share Posted August 2, 2011 1829Z PR radar. The red square to the SW of the "blob" of radar returns was the approximate position of RECON at the time, which was 211nm from the radar site (TJUA): Link to comment Share on other sites More sharing options...
Master of Disaster Posted August 2, 2011 Share Posted August 2, 2011 1829Z PR radar. The red square to the SW of the "blob" of radar returns was the approximate position of RECON at the time, which was 211nm from the radar site (TJUA): Looking at that pic though, there still appears to be some Arc clouds coming out of the system. Dry air intrusion continues?? Link to comment Share on other sites More sharing options...
Ed Lizard Posted August 2, 2011 Share Posted August 2, 2011 Looking at that pic though, there still appears to be some Arc clouds coming out of the system. Dry air intrusion continues?? Adam noted that about a page back. Between the soundings and the arc clouds, it does indeed to still be trying to digest dry air. Link to comment Share on other sites More sharing options...
lakeeffectkid383 Posted August 2, 2011 Share Posted August 2, 2011 WV Link to comment Share on other sites More sharing options...
wxsmwhrms Posted August 2, 2011 Share Posted August 2, 2011 I know there are a still a lot of issues on the smaller scale, but just taking a step back, on a broader scale this looks a lot better than 24 hours ago with better outflow, less shear, and more well developed convective features. Link to comment Share on other sites More sharing options...
MJW155 Posted August 2, 2011 Share Posted August 2, 2011 What exactly are arc clouds? The reason I ask is because there are some really high cirrus clouds outside in Ft. Lauderdale. Looks really cool actually. No idea if they are associated w/ Emily though. Link to comment Share on other sites More sharing options...
PSUBlizzicane2007 Posted August 2, 2011 Share Posted August 2, 2011 What exactly are arc clouds? The reason I ask is because there are some really high cirrus clouds outside in Ft. Lauderdale. Looks really cool actually. No idea if they are associated w/ Emily though. They are low clouds that are evidence of collapsing thunderstorms as a result of the downburst associated with the collapsing thunderstorm. Link to comment Share on other sites More sharing options...
am19psu Posted August 2, 2011 Share Posted August 2, 2011 They are evidence of collapsing thunderstorms. And more importantly, they signal the presence of cold downdrafts, which kill moist inflow into the center where the VHTs (vortical hot towers) are located. Link to comment Share on other sites More sharing options...
MJW155 Posted August 2, 2011 Share Posted August 2, 2011 They are low clouds that are evidence of collapsing thunderstorms as a result of the downburst associated with the collapsing thunderstorm. Oh OK, thanks. I had looked it up on Wiki but couldn't find anything. Link to comment Share on other sites More sharing options...
generelz Posted August 2, 2011 Share Posted August 2, 2011 Oh OK, thanks. I had looked it up on Wiki but couldn't find anything. They're also more generally referred to as outflow boundaries: http://en.wikipedia.org/wiki/Outflow_boundary Link to comment Share on other sites More sharing options...
k*** Posted August 2, 2011 Share Posted August 2, 2011 Oh OK, thanks. I had looked it up on Wiki but couldn't find anything. here's a nice little summary (it's about a conference presentation but gets the main points across) http://ams.confex.com/ams/29Hurricanes/techprogram/paper_168620.htm Arc clouds in the tropical cyclone environment: Implications for TC intensity changeJason Dunion, University of Miami/CIMAS-NOAA/HRD, Miami, FL; and M. D. Eastin, D. S. Nolan, J. Hawkins, and C. Velden Although arc clouds are common features in mid-latitude thunderstorms and MCSs, they have only occasionally been noted in tropical cyclone (TC) environments (Knaff and Weaver 2000). Arc clouds denote the presence of a density current that forms when dry middle level (~600-800 hPa) air has interacted with precipitation. The convectively-driven downdrafts that result can reach the surface/near-surface and spread out from a thunderstorm's convective core. We hypothesize that the mid-level moisture found in the moist tropical North Atlantic sounding described by Dunion and Marron (2008) is insufficiently dry to generate extensive arc clouds around African easterly waves (AEWs) or TCs. However, substantial arc clouds (100s of km in length and lasting for several hours) consistently form in the tropics in the periphery of these tropical disturbances. Dunion (2009) described two additional types of air masses that are frequently found in the tropical North Atlantic and Caribbean that could effectively initiate the formation of large arc clouds: the Saharan Air Layer and mid-latitude dry air intrusions. Both of these air masses were found to contain substantially dry air (50-60% less moisture than the moist tropical sounding) in the middle levels of the atmosphere and can affect the tropical North Atlantic and Caribbean throughout the summer months. We hypothesize that the processes leading to the formation of arc cloud events can significantly impact an AEW or TC (particularly smaller, less developed systems). Specifically, the cool, dry air associated with the convectively-driven downdrafts that form arc clouds can help stabilize the middle to lower troposphere and may even act to stabilize the boundary layer. The arc clouds themselves may also act to disrupt the storm. As they race away from the convective core region, they create low-level outflow in the quadrant/semicircle of the AEW or TC in which they form. This outflow pattern counters the typical low-level inflow that is vital for TC formation and maintenance. Examples of arc cloud events around several tropical cyclones will be discussed, as will GPS dropsonde observations launched from NOAA aircraft that sampled a few of these events in 2009. High resolution simulations of Hurricane Bill (2009) using the WRF model have been found to reproduce arc cloud events similar to those observed. Preliminary analyses show that the arc clouds are indeed triggered from the cool, dry outflow outside of decaying rainbands, in which active deep convection has been converted to stratiform precipitation by an interaction with environmental dry air. Link to comment Share on other sites More sharing options...
Ed Lizard Posted August 2, 2011 Share Posted August 2, 2011 And more importantly, they signal the presence of cold downdrafts, which kill moist inflow into the center where the VHTs (vortical hot towers) are located. What rain we got from Don in Houston came from those arcs/outflows, they developed storms as they moved inland. Interesting to watch on satellite. Link to comment Share on other sites More sharing options...
Master of Disaster Posted August 2, 2011 Share Posted August 2, 2011 What rain we got from Don in Houston came from those arcs/outflows, they developed storms as they moved inland. Interesting to watch on satellite. Looking at PR radar, thats exactly whats going on with some of them approaching that island. Link to comment Share on other sites More sharing options...
MJW155 Posted August 2, 2011 Share Posted August 2, 2011 Thanks for the links and explanations. Link to comment Share on other sites More sharing options...
am19psu Posted August 2, 2011 Share Posted August 2, 2011 New thread here: Link to comment Share on other sites More sharing options...
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