HurricaneJosh Posted February 16, 2012 Author Share Posted February 16, 2012 We have an interesting forecast "conflict" between Meteo France and the JTWC. The different agencies don't always agree, but here's a case where each is predicting exactly the opposite of what the other's saying. Bottom line: Meteo France brings Giovanna E whereas the JTWC brings it W. So, what do you think? Who's going to end up being right? Link to comment Share on other sites More sharing options...
wxmx Posted February 16, 2012 Share Posted February 16, 2012 Easy...the french are gonna get it right. Link to comment Share on other sites More sharing options...
HurricaneJosh Posted February 16, 2012 Author Share Posted February 16, 2012 Easy...the french are gonna get it right. Why don't you share your reasoning? Or, why do you think the JTWC went the way they did? (To the JTWC's defense, the Meteo France forecast is a bit more recent. The previous Meteo France forecast-- which was issued much closer to the current JTWC forecast-- was much less confident, showing only very hesitating E movement.) Link to comment Share on other sites More sharing options...
wxmx Posted February 16, 2012 Share Posted February 16, 2012 I don't know why did the JTWC went the way they did, but it looks like the currently weak steering currents might have provided with less confidence than usual. There's some ridging to the east of the storm, and a very zonal westerly flow just to the south of the storm, no troughs in the next few days. The ridge will tend to move Giovanna to the SE a bit, though I'm not sure that it will be enough to avoid Madagascar...it will be close. After that, it looks like there will be some mid latitude amplification, which could hook Giovanna and whatever becomes of Cyclone 13 out to sea. Also, the GFS and Euro show that scenario (going east). Link to comment Share on other sites More sharing options...
HurricaneJosh Posted February 16, 2012 Author Share Posted February 16, 2012 I don't know why did the JTWC went the way they did, but it looks like the currently weak steering currents might have provided with less confidence than usual. There's some ridging to the east of the storm, and a very zonal westerly flow just to the south of the storm, no troughs in the next few days. The ridge will tend to move Giovanna to the SE a bit, though I'm not sure that it will be enough to avoid Madagascar...it will be close. After that, it looks like there will be some mid latitude amplification, which could hook Giovanna and whatever becomes of Cyclone 13 out to sea. Also, the GFS and Euro show that scenario (going east). Thanks! By the way, if you're interested, here's the JTWC's discussion Re: this forecast: TROPICAL CYCLONE 12S (GIOVANNA), LOCATED APPROXIMATELY 450 NM EAST OF MAPUTO, MOZAMBIQUE, HAD TRACKED SOUTH-SOUTHWESTWARD AT 04 KNOTS OVER THE PAST SIX HOURS. ANIMATED INFRARED SATELLITE IMAGERY SHOWS THE SYSTEM HAS MAINTAINED CENTRAL CONVECTION AS IT SLOWED ON ITS FORWARD MOTION IN RESPONSE TO AN APPROACHING MID-LATITUDE TROUGH FROM THE SOUTHWEST. THE INITIAL POSITION WAS BASED ON THE ABOVE ANIMATION WITH POOR CONFIDENCE AND THE INITIAL INTENSITY WAS BASED ON DVORAK ESTIMATES FROM PGTW AND KNES. UPPER LEVEL ANALYSIS INDICATES THE SYSTEM IS APPROACHING A BREAK IN THE RIDGE IN AN AREA OF LOW (05-10 KNOT) VERTICAL WIND SHEAR. TC 12S IS TRACKING ALONG THE WESTERN PERIPHERY OF A DEEP-LAYERED SUBTROPICAL RIDGE (STR) TOTHE EAST. IT IS EXPECTED TO TRACK VERY SLOWLY WESTWARD AFTER TAU 2 AND LINGER IN THE COL BEFORE A SECONDARY STR, CURRENTLY ANCHORED OVER NORTHERN SOUTH AFRICA, EXTENDS EASTWARD AND ASSUMES STEERING TOWARD THE LATER TAUS. THIS WILL CAUSE AN EVENTUAL WEST-NORTHWEST-WARD PROJECTION OF THE STORM MOTION. THE SYSTEM WILL SLIGHTLY INTENSIFY OVER THE NEXT 24 HOURS AS VWS REMAINS LOW. BEYOND TAU 24, IT WILL GRADUALLY WEAKEN DUE TO INCREASING VWS. THE MAJORITY OF THE AVAILABLE NUMERICAL GUIDANCE RESEMBLES THIS TRACK FORECAST. ON THE OTHER HAND, GFS DEPICTS AN EASTWARD RETROGRADATION OF THE TRACK AND ECMWF PREDICTS AN EARLY RECURVATURE INTO THE WESTERLIES. THIS TRACK FORECAST IS JUST TO THE LEFT OF BUT MUCH SLOWER THAN CONSENSUS. Link to comment Share on other sites More sharing options...
HurricaneJosh Posted February 16, 2012 Author Share Posted February 16, 2012 The fresh JTWC warning is now in line with Meteo France. But like I said, the previous JTWC forecast was very old-- more than 12 hr-- so I think that was a big factor in the divergence of opinion: Link to comment Share on other sites More sharing options...
phil882 Posted February 16, 2012 Share Posted February 16, 2012 Thanks! By the way, if you're interested, here's the JTWC's discussion Re: this forecast: TROPICAL CYCLONE 12S (GIOVANNA), LOCATED APPROXIMATELY 450 NM EAST OF MAPUTO, MOZAMBIQUE, HAD TRACKED SOUTH-SOUTHWESTWARD AT 04 KNOTS OVER THE PAST SIX HOURS. ANIMATED INFRARED SATELLITE IMAGERY SHOWS THE SYSTEM HAS MAINTAINED CENTRAL CONVECTION AS IT SLOWED ON ITS FORWARD MOTION IN RESPONSE TO AN APPROACHING MID-LATITUDE TROUGH FROM THE SOUTHWEST. THE INITIAL POSITION WAS BASED ON THE ABOVE ANIMATION WITH POOR CONFIDENCE AND THE INITIAL INTENSITY WAS BASED ON DVORAK ESTIMATES FROM PGTW AND KNES. UPPER LEVEL ANALYSIS INDICATES THE SYSTEM IS APPROACHING A BREAK IN THE RIDGE IN AN AREA OF LOW (05-10 KNOT) VERTICAL WIND SHEAR. TC 12S IS TRACKING ALONG THE WESTERN PERIPHERY OF A DEEP-LAYERED SUBTROPICAL RIDGE (STR) TOTHE EAST. IT IS EXPECTED TO TRACK VERY SLOWLY WESTWARD AFTER TAU 2 AND LINGER IN THE COL BEFORE A SECONDARY STR, CURRENTLY ANCHORED OVER NORTHERN SOUTH AFRICA, EXTENDS EASTWARD AND ASSUMES STEERING TOWARD THE LATER TAUS. THIS WILL CAUSE AN EVENTUAL WEST-NORTHWEST-WARD PROJECTION OF THE STORM MOTION. THE SYSTEM WILL SLIGHTLY INTENSIFY OVER THE NEXT 24 HOURS AS VWS REMAINS LOW. BEYOND TAU 24, IT WILL GRADUALLY WEAKEN DUE TO INCREASING VWS. THE MAJORITY OF THE AVAILABLE NUMERICAL GUIDANCE RESEMBLES THIS TRACK FORECAST. ON THE OTHER HAND, GFS DEPICTS AN EASTWARD RETROGRADATION OF THE TRACK AND ECMWF PREDICTS AN EARLY RECURVATURE INTO THE WESTERLIES. THIS TRACK FORECAST IS JUST TO THE LEFT OF BUT MUCH SLOWER THAN CONSENSUS. Yea, I'd say this is probably going to verify much further west than the old JTWC track... Link to comment Share on other sites More sharing options...
icebreaker5221 Posted February 16, 2012 Share Posted February 16, 2012 The fresh JTWC is now in line with Meteo France. But like I said, the previous JTWC forecast was very old-- more than 12 hr-- so I think that was a big factor in the divergence of opinion: 12Z GFS looks pretty close to this. Kinda meanders for a couple days without doing much of anything, almost does a loop, and makes landfall over the extreme SW corner of the island. I would think that a storm sitting over one location for that long would lead to some upwelling, although the Agulhas current is quite strong between Madigascar and mainland Africa and should probably replace most of the heat loss. Giovanna left a -2C wake east of the island, but the storm is a lot weaker now. Probably the biggest factor against re-intensification to hurricane strength is the disruption of the core with that nasty topography. Shear is generally light, though increases substantially to the southeast. Also, check out this difluence to the west of Giovanna (not unrelated to the divergence of tracks we saw earlier). Link to comment Share on other sites More sharing options...
wxmx Posted February 16, 2012 Share Posted February 16, 2012 Yep. P.S. I like the new avatar. It's very "tropical dude". Where's it from? Link to comment Share on other sites More sharing options...
HurricaneJosh Posted February 19, 2012 Author Share Posted February 19, 2012 Days later, and Giovanna is still on the map-- and has actually become a hurricane again as it makes a grand loop around Madagascar. Currently, the cyclone is S of the island and moving E, with winds of 65 kt. It should turn N and weaken over the next couple of days. Link to comment Share on other sites More sharing options...
aslkahuna Posted February 20, 2012 Share Posted February 20, 2012 Giovanna has pulled an EPAC. LLCC headed NW and fully exposed, mid level moisture charging SE in the westerlies-it has sheared apart and it's remnant low time. Steve Link to comment Share on other sites More sharing options...
HurricaneJosh Posted February 21, 2012 Author Share Posted February 21, 2012 Giovanna has pulled an EPAC. LLCC headed NW and fully exposed, mid level moisture charging SE in the westerlies-it has sheared apart and it's remnant low time. Steve Wow-- sounds depressing! Link to comment Share on other sites More sharing options...
aslkahuna Posted February 21, 2012 Share Posted February 21, 2012 Wow-- sounds depressing! Giovanna has been finalled out and it has become to classical naked swirl. Steve Link to comment Share on other sites More sharing options...
HurricaneJosh Posted February 24, 2012 Author Share Posted February 24, 2012 The Euro is showing a small, intense cyclone snaking S, down the Mozambique Channel, during the Day 6-10 period: Link to comment Share on other sites More sharing options...
HurricaneJosh Posted February 25, 2012 Author Share Posted February 25, 2012 The Euro continues to advertise mischief in the Mozambique Channel, with the 12Z run showing a cyclone forming by Day 5 and coming ashore as an intense storm in Mozambique by Day 9. Link to comment Share on other sites More sharing options...
aslkahuna Posted February 25, 2012 Share Posted February 25, 2012 The Euro continues to advertise mischief in the Mozambique Channel, with the 12Z run showing a cyclone forming by Day 5 and coming ashore as an intense storm in Mozambique by Day 9. nJTWC agrees calling for a formative disturbance to brush by northern Madagascar and then intensify in the Mozambique Channel. Steve Link to comment Share on other sites More sharing options...
HurricaneJosh Posted February 26, 2012 Author Share Posted February 26, 2012 JTWC agrees calling for a formative disturbance to brush by northern Madagascar and then intensify in the Mozambique Channel. Steve Yep-- I just noticed the formation alert. Cool-- something to track. Oz remains completely barren-- just a dreadful dry spell during their peak season. The Oz chaser dudes must be pissed. They're great guys and very serious about their chasing-- I hope they get some action before the season's out. Link to comment Share on other sites More sharing options...
HurricaneJosh Posted February 26, 2012 Author Share Posted February 26, 2012 In the last day or so, a weak cyclone named Irina formed and made landfall in NE Madagascar, and the remnant low is moving WSW across the island. Meteo France calls for it to regenerate in the Mozambique Channel and become intense within the next few days: Link to comment Share on other sites More sharing options...
aslkahuna Posted February 26, 2012 Share Posted February 26, 2012 JT never carried it as a TC. The mid level circulation looks fairly intact and oter aspects of the system suggest that it should takeoff once it coasts out. Steve Link to comment Share on other sites More sharing options...
Ed Lizard Posted February 26, 2012 Share Posted February 26, 2012 Yep-- I just noticed the formation alert. Cool-- something to track. Oz remains completely barren-- just a dreadful dry spell during their peak season. The Oz chaser dudes must be pissed. They're great guys and very serious about their chasing-- I hope they get some action before the season's out. They seem to be trying to remain glass half full: From Oz Cyclone Chaser's FB page... Models this morning show a fresh easterly flow in the Northern Hemisphere about to cross the equator starting late today or tomorrow resultingin the formation of a weak monsoon trough stretching from Indonesia through to the far northern Coral Sea in 2-3 days time. ... The development of a monsoonal trough about 6 days earlier than forecast by climatic modelling is throwing a spanner in the works and complicating medium range forecasts at the moment. We did not expect this fresh pulse of Easterly winds north of the equator so soon, and so the entire region will need to be monitored closely starting mid to late this week. Link to comment Share on other sites More sharing options...
HurricaneJosh Posted February 29, 2012 Author Share Posted February 29, 2012 Irina has been lingering along the N coast of Madagascar for a couple of days. Both Meteo France and the JTWC now bring it across the the Channel and ashore in Mozambique as a hurricane in a few days. Link to comment Share on other sites More sharing options...
am19psu Posted February 29, 2012 Share Posted February 29, 2012 On the Aussie side... *yawn* until about Mar 9-10. Link to comment Share on other sites More sharing options...
HurricaneJosh Posted February 29, 2012 Author Share Posted February 29, 2012 On the Aussie side... *yawn* until about Mar 9-10. And then what...? Link to comment Share on other sites More sharing options...
am19psu Posted February 29, 2012 Share Posted February 29, 2012 And then what...? Something forms in the Timor Sea. Pretty strong signal for a decent storm, but might be a fish Link to comment Share on other sites More sharing options...
HurricaneJosh Posted March 1, 2012 Author Share Posted March 1, 2012 Irina has spilled out into the Mozambique Channel and should regenerate. The latest JTWC warning has shifted the forecast track S, suggesting a threat to Mozambique's capital and largest city, Maputo (pop. ~1.2 million): Link to comment Share on other sites More sharing options...
HurricaneJosh Posted March 3, 2012 Author Share Posted March 3, 2012 Latest forecast from JTWC and Meteo France have Irina looping offshore of Mozambique and never reaching hurricane strength. Boring. Link to comment Share on other sites More sharing options...
HurricaneJosh Posted March 4, 2012 Author Share Posted March 4, 2012 Irina is looping around off the Mozambique coast as a weak TS. Blah. In other S-Hemisphere news... This non-classified system on the Australian coast near Rainbow Beach (a bit N of Brisbane) has a remarkably mature radar presentation-- banding and all. Wow. It's contributing to major flooding in New South Wales: Link to comment Share on other sites More sharing options...
HurricaneJosh Posted March 6, 2012 Author Share Posted March 6, 2012 Irina's a little confused. WTF? Link to comment Share on other sites More sharing options...
am19psu Posted March 6, 2012 Share Posted March 6, 2012 On the Aussie side... *yawn* until about Mar 9-10. What a piece of garbage this system has trended towards. Link to comment Share on other sites More sharing options...
HurricaneJosh Posted March 6, 2012 Author Share Posted March 6, 2012 What a piece of garbage this system has trended towards. Can't believe how epically lame peak season has been for Oz. It's just this big, gaping hole in the activity pattern. Link to comment Share on other sites More sharing options...
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