icebreaker5221 Posted July 23, 2013 Share Posted July 23, 2013 18z tracks have shifted south a bit with the TVCN looking interesting. AL98_current.png The ECMWF, while often the best, is currently well outside of the consensus which leads me to believe it could be wrong. It has AL98 approaching 22N at 72 h, which would make it more than twice as far north from the consensus as the next biggest outlier. Link to comment Share on other sites More sharing options...
Superstorm93 Posted July 23, 2013 Share Posted July 23, 2013 The ECMWF, while often the best, is currently well outside of the consensus which leads me to believe it could be wrong. It has AL98 approaching 22N at 72 h, which would make it more than twice as far north from the consensus as the next biggest outlier. I have to be honest, the 12z ECMWF track looks highly unlikely. http://ruc.noaa.gov/hfip/tcdiag/tcdiag.php?model=rtfim9 TAFB is on the southern portion of the guidance with a decent low @ 72 hours Link to comment Share on other sites More sharing options...
Ed Lizard Posted July 23, 2013 Share Posted July 23, 2013 Easterly shear? Link to comment Share on other sites More sharing options...
TropicalAnalystwx13 Posted July 23, 2013 Share Posted July 23, 2013 Easterly shear? That image is nearly three hours old and the center has become ever so slightly tucked into the eastern side of the convection, but yeah, it's been experiencing easterly shear. 12z SHIPS initialized with 21 knots of shear and the 18z SHIPS initialized with 12 knots. Should see a further decrease throughout the night. Link to comment Share on other sites More sharing options...
wxmeddler Posted July 23, 2013 Share Posted July 23, 2013 Easterly shear? Yep. Maxes out at 540mb. Link to comment Share on other sites More sharing options...
IsentropicLift Posted July 23, 2013 Share Posted July 23, 2013 The presentation looks good right now, looks like it could get classified at any time. Link to comment Share on other sites More sharing options...
phil882 Posted July 23, 2013 Share Posted July 23, 2013 Just needs a little bit more convection... although that will be increasingly difficult to come by as it continues to move into a more stable atmosphere. Link to comment Share on other sites More sharing options...
yoda Posted July 23, 2013 Share Posted July 23, 2013 Better hurry... 18z GFS FWIW says its gone in 36 hrs Link to comment Share on other sites More sharing options...
Ed Lizard Posted July 23, 2013 Share Posted July 23, 2013 Better hurry... 18z GFS FWIW says its gone in 36 hrs Not completely gone Link to comment Share on other sites More sharing options...
phil882 Posted July 23, 2013 Share Posted July 23, 2013 I think we see this get classified tonight... convection is starting to build over the llc, and while not particularly deep, its sufficient in coverage and intensity to be considered a TC. The bubbly like appearance in the convection is a good sign right now, indicating dry air hasn't penetrated the core yet. Another factor that hasn't really gotten much press; there is a distinct lack of SAL associated with 98L. It doesn't look like there is a surge getting ready to emerge off the African coast either. This is pretty rare for late July where AEWs are usually dominated by SAL outbreaks. Link to comment Share on other sites More sharing options...
wxmeddler Posted July 24, 2013 Share Posted July 24, 2013 This would be a great case study for HS3... Far eastern wave, with pouch and SAL doing the dance. Too bad the missions don't start until Aug. 20th. They had a virtual press conference today if you want to watch it on youtube. Link to comment Share on other sites More sharing options...
Floydbuster Posted July 24, 2013 Share Posted July 24, 2013 I think we see this get classified tonight... convection is starting to build over the llc, and while not particularly deep, its sufficient in coverage and intensity to be considered a TC. The bubbly like appearance in the convection is a good sign right now, indicating dry air hasn't penetrated the core yet. Another factor that hasn't really gotten much press; there is a distinct lack of SAL associated with 98L. It doesn't look like there is a surge getting ready to emerge off the African coast either. This is pretty rare for late July where AEWs are usually dominated by SAL outbreaks. If that keeps up during the peak wave time in August and September, could mean many Cape Verde systems. Link to comment Share on other sites More sharing options...
phil882 Posted July 24, 2013 Share Posted July 24, 2013 There was another note made earlier today about the further west 18z ATCF guidance (which a large portion are at least influenced by the 12z GFS) and the much faster and further NW ECMWF. I agree that the ECMWF doesn't seem to be handeling the sub-synoptic environment around 98L very well. Let me explain. The low-level circulation of 98L is very distinct. However, within the AEW envelope, there is also another piece of energy that emerged off the African coastline today. This has resulted in a elongated 500 hPa vorticity envelope extending west to east, since there is broad mid-level turning associated with the decaying MCS that moved out over open waters between Africa and the Cape Verde islands. Based on the 12z runs today, the GFS seems to capture this more elongated 500 hPa vorticity pattern vs. the ECMWF which has the 500 hPa vorticity associated with 98L extending too far to the NW. This has been a persistent bias in the model with this invest. The end effect of this is that the ECMWF has falsely eroded the mid-level ridge ahead of 98L by depicting convection, and hence vorticity, cutting into the relatively weak mid-level ridge in place. The GFS correctly hangs the mid-level vorticity further back, allowing for a stronger ridge, and a more southward motion of the vortex. I'd be very surprised to see the ECMWF verify in the short term. You can see how the 500 hPa heights (white contours) are eroded more on the ECMWF than the GFS. This is what is leading to the initial (and perhaps long-term) track disparity between the two models. Link to comment Share on other sites More sharing options...
Ed Lizard Posted July 24, 2013 Share Posted July 24, 2013 18Z 15km FIM just starting to get interesting w/ 98L when it crashes into Hispaniola. IF it survives (near term and avoids Greater Antilles), could be the interesting system. Link to comment Share on other sites More sharing options...
Superstorm93 Posted July 24, 2013 Share Posted July 24, 2013 This is probably classifiable. Link to comment Share on other sites More sharing options...
Srain Posted July 24, 2013 Share Posted July 24, 2013 Those NCEP TC Genesis Probabilities late last week don't seem so wrong after all... Link to comment Share on other sites More sharing options...
phil882 Posted July 24, 2013 Share Posted July 24, 2013 This is probably classifiable. WMBas124.png 20130724.0000.msg3.x.ir1km.98LINVEST.25kts-1008mb-133N-256W.100pc.jpg Thats a very impressive ASCAT pass with widespread 25-30 knot wind vectors. ASCAT typically has a low bias and its NHC will probably pull the trigger based on this and the slightly improved satellite presentation tonight. Link to comment Share on other sites More sharing options...
wxmx Posted July 24, 2013 Share Posted July 24, 2013 Agree Phil, this looks like the evidence the NHC needs to upgrade to TD. Now back to following the struggling cyclone. It will probably go thru the naked swirl process that has been the theme the past few seasons at some point in it's life. Link to comment Share on other sites More sharing options...
TropicalAnalystwx13 Posted July 24, 2013 Share Posted July 24, 2013 It'll be interesting to see just how well 98L holds up against the unfavorable conditions ahead. As evidenced by the above images, SAL has thinned out significantly over the past few days. A large area of dry air lurks to the northwest, but with easterly flow across the region, I wouldn't be surprised if what happened with Chantal occurred again (the storm moving in tandem with the stable air) here; 98L has a large moisture bubble anyways. I think the biggest issue will be the 25-26C sea surface temperatures it crosses tomorrow and Thursday. Link to comment Share on other sites More sharing options...
Derecho! Posted July 24, 2013 Share Posted July 24, 2013 . I'd be very surprised to see the ECMWF verify in the short term. The 0Z NHC model init was a motion of 285 degrees; not saying the extreme ECMWF solution will verify but it definitely looks to have made a turn to a bit more N of W component late this afternoon. Link to comment Share on other sites More sharing options...
phil882 Posted July 24, 2013 Share Posted July 24, 2013 The 0Z NHC model init was a motion of 285 degrees; not saying the extreme ECMWF solution will verify but it definitely looks to have made a turn to a bit more N of W component late this afternoon. Well yes, but that would still be well within the forecasted GFS track. The ECMWF is already too far north and west at 03z where it had the center at 14.5N 26.5W... while the true center is on the NE edge of the convection, more around 13.5N 25.5W ECMWF 03z Forecast compared with satellite imagery. 03z GFS compared with satellite imagery. While not perfect, the GFS is doing a superior job. Link to comment Share on other sites More sharing options...
Superstorm93 Posted July 24, 2013 Share Posted July 24, 2013 000ABNT20 KNHC 240240TWOATSPECIAL TROPICAL WEATHER OUTLOOKNWS NATIONAL HURRICANE CENTER MIAMI FL1040 PM EDT TUE JUL 23 2013FOR THE NORTH ATLANTIC...CARIBBEAN SEA AND THE GULF OF MEXICO...SATELLITE-DERIVED WIND DATA INDICATE THAT THE SURFACE LOW PRESSURESYSTEM LOCATED ABOUT 150 MILES SOUTHWEST OF THE CAPE VERDE ISLANDSIS PRODUCING WINDS TO NEAR GALE FORCE. HOWEVER...THE ASSOCIATEDTHUNDERSTORM ACTIVITY REMAINS SOMEWHAT LIMITED AND HAS NOT YET BEENPERSISTENT ENOUGH FOR THE LOW TO BE DESIGNATED AS A TROPICALCYCLONE. IF THE THUNDERSTORMS INCREASE AND PERSIST...THEN THE LOWCOULD BECOME A TROPICAL DEPRESSION OR TROPICAL STORM ON WEDNESDAYAS IT MOVES WEST-NORTHWESTWARD AT ABOUT 20 MPH. THIS SYSTEM HAS AHIGH CHANCE...70 PERCENT...OF BECOMING A TROPICAL CYCLONE DURINGTHE NEXT 48 HOURS. Link to comment Share on other sites More sharing options...
Floydbuster Posted July 24, 2013 Share Posted July 24, 2013 Link to comment Share on other sites More sharing options...
phil882 Posted July 24, 2013 Share Posted July 24, 2013 000ABNT20 KNHC 240240 TWOAT SPECIAL TROPICAL WEATHER OUTLOOK NWS NATIONAL HURRICANE CENTER MIAMI FL 1040 PM EDT TUE JUL 23 2013 FOR THE NORTH ATLANTIC...CARIBBEAN SEA AND THE GULF OF MEXICO... SATELLITE-DERIVED WIND DATA INDICATE THAT THE SURFACE LOW PRESSURE SYSTEM LOCATED ABOUT 150 MILES SOUTHWEST OF THE CAPE VERDE ISLANDS IS PRODUCING WINDS TO NEAR GALE FORCE. HOWEVER...THE ASSOCIATED THUNDERSTORM ACTIVITY REMAINS SOMEWHAT LIMITED AND HAS NOT YET BEEN PERSISTENT ENOUGH FOR THE LOW TO BE DESIGNATED AS A TROPICAL CYCLONE. IF THE THUNDERSTORMS INCREASE AND PERSIST...THEN THE LOW COULD BECOME A TROPICAL DEPRESSION OR TROPICAL STORM ON WEDNESDAY AS IT MOVES WEST-NORTHWESTWARD AT ABOUT 20 MPH. THIS SYSTEM HAS A HIGH CHANCE...70 PERCENT...OF BECOMING A TROPICAL CYCLONE DURING THE NEXT 48 HOURS. ScreenHunter_53 Jul. 23 22.48.png Splitting hairs... this is a TD/TS for all intents and purposes. The convection currently is sufficent and as long as it doesn't go poof tonight, it will be classified at 5am. Link to comment Share on other sites More sharing options...
phil882 Posted July 24, 2013 Share Posted July 24, 2013 Link to comment Share on other sites More sharing options...
wxmx Posted July 24, 2013 Share Posted July 24, 2013 Troublemaker Link to comment Share on other sites More sharing options...
TropicalAnalystwx13 Posted July 24, 2013 Share Posted July 24, 2013 Looks like it'll be 5am. 1. SHOWER AND THUNDERSTORM ACTIVITY ASSOCIATED WITH A LOW PRESSURESYSTEM LOCATED ABOUT 175 MILES WEST-SOUTHWEST OF THE CAPE VERDEISLANDS HAS INCREASED IN COVERAGE AND ORGANIZED DURING THE PASTSEVERAL HOURS. IF THESE TRENDS CONTINUE...TROPICAL CYCLONEADVISORIES WILL LIKELY BE INITIATED LATER THIS MORNING. THISSYSTEM HAS A HIGH CHANCE...80 PERCENT...OF BECOMING A TROPICALCYCLONE DURING THE NEXT 48 HOURS AS IT MOVES WEST-NORTHWESTWARDAT ABOUT 20 MPH. Link to comment Share on other sites More sharing options...
phil882 Posted July 24, 2013 Share Posted July 24, 2013 00z ECMWF is stronger and much slower with the 98L vortex. Very much in line with the GFS and the rest of the guidance. Game on! Link to comment Share on other sites More sharing options...
andyhb Posted July 24, 2013 Share Posted July 24, 2013 Solid looking convective burst currently approaching d-max. Link to comment Share on other sites More sharing options...
phil882 Posted July 24, 2013 Share Posted July 24, 2013 You can see how much better the 00z ECMWF run is doing compared to the 12z run. 12z ECMWF valid at 06z today: 00z ECMWF valid at 06z Today: Link to comment Share on other sites More sharing options...
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