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Tropical Storm LOWELL Forecast Discussion Number 24

2014-08-23 23:28:25| Tropical Depression LIDIA

Issued at 200 PM PDT SAT AUG 23 2014

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Tropical Depression FOUR Forecast Discussion Number 1

2014-08-23 22:48:54| National Hurricane Center (Atlantic)

Issued at 500 PM AST SAT AUG 23 2014 000 WTNT44 KNHC 232048 TCDAT4 TROPICAL DEPRESSION FOUR DISCUSSION NUMBER 1 NWS NATIONAL HURRICANE CENTER MIAMI FL AL042014 500 PM AST SAT AUG 23 2014 The Air Force Reserve Hurricane Hunter aircraft investigating the disturbance near the southeastern Bahamas found a well-defined circulation this afternoon. Even though the convective presentation is somewhat ragged, there is enough organization to classify the system as a tropical cyclone. The intensity is set to 30 kt based on flight level wind data from the aircraft and an earlier ASCAT pass, and the central pressure of 1005 mb is based on a recent surface observation from Providenciales in the Turks and Caicos. The SHIPS model shows light to moderate shear over the cyclone for the next couple of days, which should allow for intensification given that the cyclone will be moving over waters of 29 to 30C. The NHC forecast shows slow strengthening in the first 24 to 36 hours as the cyclone organizes. Global models show more favorable upper- level winds over the system in a couple of days, which should allow for strengthening to a hurricane in by 3 days. The official forecast is close to the IVCN intensity consensus through the period. The initial motion estimate is a relatively uncertain 310/10 given the recent formation of the center. The cyclone should continue moving northwestward and north-northwestward into a developing break in the subtropical ridge cause by a mid/upper-level trough off the U.S. east coast. As the trough begins to lift out and steering currents weaken, a slow motion is expected in 36 to 48 hours. Then as a subtropical ridge rebuilds to the east of the cyclone later in the period, the system is expected to turn northward and then northeastward. However, there is significant disagreement in the timing and sharpness of the turn in this and previous dynamical model cycles. Currently the GFDL and GFS are along the western edge of the guidance envelope showing a more westward track and a slower motion at day 5. The ECMWF, GEFS mean, and HWRF show a sharper turn and a more northeastward motion by day 5 on the east side of the guidance envelope. The NHC forecast is near the TVCA multi-model consensus through most of the period and a little to the left of it at day 5. Given the spread in the guidance and the recent formation of the system, confidence in the details of the track forecast is lower than normal. FORECAST POSITIONS AND MAX WINDS INIT 23/2100Z 21.8N 72.3W 30 KT 35 MPH 12H 24/0600Z 22.9N 73.6W 35 KT 40 MPH 24H 24/1800Z 24.0N 74.4W 40 KT 45 MPH 36H 25/0600Z 24.6N 74.8W 45 KT 50 MPH 48H 25/1800Z 25.0N 75.0W 55 KT 65 MPH 72H 26/1800Z 26.5N 76.0W 65 KT 75 MPH 96H 27/1800Z 29.0N 77.5W 65 KT 75 MPH 120H 28/1800Z 32.0N 76.5W 70 KT 80 MPH $$ Forecaster Brennan

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Hurricane KARINA Forecast Discussion Number 44

2014-08-23 22:47:52| National Hurricane Center (East Pacific)

Issued at 200 PM PDT SAT AUG 23 2014 000 WTPZ41 KNHC 232047 TCDEP1 HURRICANE KARINA DISCUSSION NUMBER 44 NWS NATIONAL HURRICANE CENTER MIAMI FL EP112014 200 PM PDT SAT AUG 23 2014 The eye of Karina has begun to fill during the past few hours, and deep convection has decreased slightly on the north side of the cyclone. A blend of the 1800 UTC Dvorak CI- and T-numbers still yields an initial wind speed estimate of 70 kt. Since that time, the cloud pattern of the cyclone has begun to deteriorate, suggesting that the predicted weakening trend may already be occurring. The hurricane is currently crossing the 26 deg C isotherm and dry air is wrapping around the circulation, as seen in total precipitable water imagery. The influence of these unfavorable thermodynamic factors should cause steady weakening to remnant low status in 3 to 4 days. The NHC intensity forecast is again an update of the previous one and lies close to the multi-model consensus. Karina is turning toward the right in the broad southwesterly flow to the south of Lowell, and the latest initial motion estimate is 055/6. The models are coming into better agreement in showing Karina moving on a general east-northeasterly path with a decrease in forward speed before being absorbed into the much larger circulation of Hurricane Marie in 4 to 5 days. However, there is still some guidance that shows Karina interacting with Lowell, which would result in a west-northwestward motion. Since most of the track guidance now favors the absorption of Karina by Marie, the NHC track forecast has been adjusted eastward and shows the cyclone becoming stationary at days 3 and 4. FORECAST POSITIONS AND MAX WINDS INIT 23/2100Z 17.3N 133.5W 70 KT 80 MPH 12H 24/0600Z 17.7N 132.4W 60 KT 70 MPH 24H 24/1800Z 18.0N 130.7W 55 KT 65 MPH 36H 25/0600Z 18.3N 129.1W 45 KT 50 MPH 48H 25/1800Z 18.6N 128.2W 35 KT 40 MPH 72H 26/1800Z 19.0N 127.7W 30 KT 35 MPH 96H 27/1800Z 19.0N 127.7W 25 KT 30 MPH...POST-TROP/REMNT LOW 120H 28/1800Z...DISSIPATED $$ Forecaster Cangialosi

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Hurricane MARIE Forecast Discussion Number 8

2014-08-23 22:46:52| National Hurricane Center (East Pacific)

Issued at 200 PM PDT SAT AUG 23 2014 000 WTPZ43 KNHC 232046 TCDEP3 HURRICANE MARIE DISCUSSION NUMBER 8 NWS NATIONAL HURRICANE CENTER MIAMI FL EP132014 200 PM PDT SAT AUG 23 2014 Marie's rapid intensification has slowed some this afternoon. Symmetric, cold cloud tops are persisting in association with the hurricane and a ragged eye is just now starting to make an appearance in the visible imagery. Dvorak CI numbers from ADT, SAB, and TAFB have not changed over the last six hours, but with an eye evident the intensity is increased slightly to 80 kt. Continued intensification is expected, but how much is fairly uncertain. The SSTs, moisture, and convective instability are likely to continue being very conducive for the next three days. However, the GFS-based vertical shear within the SHIPS model suggests about 15 kt of deep-layer shear now and for the next three days. The forecast intensity is close to the SHIPS statistical model through three days, which is higher than any of the other guidance. It is of note that the GFDL dynamical model barely maintains Marie as a hurricane for the next three days, though this is considered an unlikely scenario at this time. By days four and five, Marie should be passing over cold waters and moving into a stable atmosphere. The forecast intensity at the long-lead times is close to the IVCN consensus. This official intensity prediction is slightly below that provided in the previous advisory from 48 hours onward. TRMM and SSMIS microwave imagery provided evidence of the developing eye feature and allowed for a more accurate determination of the initial position and motion. The current motion is west-northwest at 10 kt, about the same as previously. Marie is primarily being steered by a deep-layer ridge to its northeast, which should continue being the main steering factor for the entire forecast period. The track guidance remains in very close agreement through day 5 and suggests more confidence than usual in the forecast track. The official track prediction at days four and five is shifted slightly westward compared to the previous advisory and is based upon the multi-model TVCN consensus technique. It is of note that small-sized Hurricane Karina is now expected by most models to be absorbed into the circulation of Marie in about four days. While this process will lead to the dissipation of Karina, it should have little effect on the larger-sized Marie. FORECAST POSITIONS AND MAX WINDS INIT 23/2100Z 15.1N 107.6W 80 KT 90 MPH 12H 24/0600Z 15.6N 109.4W 90 KT 105 MPH 24H 24/1800Z 16.1N 111.4W 100 KT 115 MPH 36H 25/0600Z 16.8N 113.1W 110 KT 125 MPH 48H 25/1800Z 17.8N 114.8W 115 KT 135 MPH 72H 26/1800Z 20.6N 118.3W 100 KT 115 MPH 96H 27/1800Z 23.0N 123.0W 70 KT 80 MPH 120H 28/1800Z 25.5N 128.0W 45 KT 50 MPH $$ Forecaster Landsea

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Hurricane MARIE Forecast Discussion Number 7

2014-08-23 16:46:51| National Hurricane Center (East Pacific)

Issued at 800 AM PDT SAT AUG 23 2014 000 WTPZ43 KNHC 231446 TCDEP3 HURRICANE MARIE DISCUSSION NUMBER 7 NWS NATIONAL HURRICANE CENTER MIAMI FL EP132014 800 AM PDT SAT AUG 23 2014 Marie has been rapidly intensifying with a 30-kt increase since yesterday at this time. Symmetric, cold cloud tops are persisting in association with the hurricane, though an eye has yet to make an appearance. Dvorak CI numbers are increasing, and a blend of the ADT, SAB, and TAFB values indicate an intensity of 75 kt. Continued intensification is expected, but how much is fairly uncertain. The SSTs, moisture, and convective instability are likely to continue being very conducive for the next three days. The GFS-based vertical shear within the SHIPS model suggests about 10-15 kt of deep-layer shear currently and gradually increasing over next three days. However, the CIMSS shear analysis suggests substantially less shear now, which is more consistent with the symmetric appearance to the convection and the observed rapid intensification. The forecast intensity is close to the SHIPS statistical model through three days, which is higher than any of the other guidance. By days four and five, Marie should be passing over cold waters and moving into a stable atmosphere. The forecast intensity at the long-lead times is close to the IVCN consensus. This official intensity prediction is slightly below that provided in the previous advisory from 36 hours onward. Unfortunately, no new size information has been available and the wind radii analysis and prediction remain about the same. The initial position is somewhat uncertain, due to no microwave passes recently and no eye being seen yet. However, the available fixes suggest a somewhat farther northward position than earlier analyzed. The current motion is west-northwest at 9 kt, slightly slower than previously. Marie is primarily being steered by a deep-layer ridge to its northeast, which should continue being the main steering factor for the entire forecast time. The track guidance is in very close agreement all the way to five days and suggests more confidence than usual in the forecast track. The official track prediction is just slightly northward of the previous advisory because of the initial shift in position, but is otherwise quite close in longitude. FORECAST POSITIONS AND MAX WINDS INIT 23/1500Z 14.6N 106.3W 75 KT 85 MPH 12H 24/0000Z 15.2N 107.9W 90 KT 105 MPH 24H 24/1200Z 15.9N 110.0W 100 KT 115 MPH 36H 25/0000Z 16.5N 111.8W 110 KT 125 MPH 48H 25/1200Z 17.3N 113.5W 120 KT 140 MPH 72H 26/1200Z 19.7N 117.0W 105 KT 120 MPH 96H 27/1200Z 22.0N 121.0W 80 KT 90 MPH 120H 28/1200Z 25.0N 126.0W 55 KT 65 MPH $$ Forecaster Landsea

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