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Tropical Storm KARINA Forecast Discussion Number 29
2014-08-20 04:37:02| National Hurricane Center (East Pacific)
Issued at 800 PM PDT TUE AUG 19 2014 000 WTPZ41 KNHC 200236 TCDEP1 TROPICAL STORM KARINA DISCUSSION NUMBER 29 NWS NATIONAL HURRICANE CENTER MIAMI FL EP112014 800 PM PDT TUE AUG 19 2014 Deep convection with cloud tops colder than -80C has redeveloped near Karina's center, and convective banding features have improved during the past 6 hours now that the cyclone is moving over a ridge of warmer sea surface temperatures. The result is that intensity estimates from both TAFB and SAB have increased to a consensus T3.0/45 kt, so the initial intensity is being held at 45 kt. Karina is moving slowly westward or 275/04 kt. There remains no significant change to the previous reasoning. Karina is forecast to stall and/or make a small loop in 24 to 48 hours when steering currents are forecast to weaken considerably. By 72 hours and beyond, the cyclone is expected to come under the influence of southwesterly steering flow generated by the very large circulation of Tropical Storm Lowell, which is currently located well to the east of Karina. The NHC model guidance is actually in very good agreement on the development of this rather complex synoptic flow pattern and eventual interaction between the two tropical cyclones. The only significant difference since the previous advisory is that the model guidance envelope has shifted well to the east. The official forecast track follows suit and has been shifted slightly to the east, but not nearly as far east as the consensus model TVCE due to the uncertainty in which direction Karina will move after the cyclone stalls and/or completes a looping motion. The outflow from Tropical Storm Lowell is expected to affect Karina within the next 12 hours, producing modest easterly to southeasterly vertical wind shear across the cyclone through 72 hours. The result is that little change in intensity is forecast, although there will likely be some small fluctuations in the intensity during that time. By 72 hours and beyond, the shear is expected to steadily increase as Karina moves closer to Tropical Storm Lowell, which should induce steady weakening. By Day 5, Karina will be moving over 22C SSTs, causing the system to degenerate into a post-tropical remnant low pressure system. The NHC intensity forecast is just an update of the previous advisory and closely follows the consensus intensity model ICON. FORECAST POSITIONS AND MAX WINDS INIT 20/0300Z 15.9N 135.3W 45 KT 50 MPH 12H 20/1200Z 15.9N 135.8W 45 KT 50 MPH 24H 21/0000Z 16.0N 136.2W 45 KT 50 MPH 36H 21/1200Z 15.8N 136.2W 45 KT 50 MPH 48H 22/0000Z 15.6N 135.7W 45 KT 50 MPH 72H 23/0000Z 16.7N 134.0W 40 KT 45 MPH 96H 24/0000Z 19.5N 130.5W 30 KT 35 MPH 120H 25/0000Z 24.0N 128.3W 25 KT 30 MPH...POST-TROP/REMNT LOW $$ Forecaster Stewart
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