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Tropical Storm KARINA Forecast Discussion Number 35

2014-08-21 16:35:13| National Hurricane Center (East Pacific)

Issued at 800 AM PDT THU AUG 21 2014 000 WTPZ41 KNHC 211435 TCDEP1 TROPICAL STORM KARINA DISCUSSION NUMBER 35 NWS NATIONAL HURRICANE CENTER MIAMI FL EP112014 800 AM PDT THU AUG 21 2014 Although Karina's appearance on geostationary satellite imagery is not very impressive, a recent GPM microwave satellite image showed a partial eyewall feature. This indicates that the inner core is well defined, and the intensity estimate is increased to 50 kt, which is a little above the latest Dvorak estimates. It appears that the vertical shear over the storm has relaxed a little, but Karina is over marginal sea surface temperatures and the forecast track takes the cyclone over cooler waters. A weakening trend is likely to commence in 24 hours or so, as shown by the official wind speed forecast. This forecast is a little below the intensity model consensus. Based on an excellent fix from the aforementioned microwave image, the center has been repositioned a bit south of the previously estimated track. This yields an initial motion estimate of 180/2 kt. Karina remains in an environment of weak steering currents at this time. However, as the larger Hurricane Lowell moves northwest, the separation distance between Karina and Lowell will be decreasing, which will increase the influence of the latter cyclone on the former. The flow over the southern and southeastern portions of Lowell's circulation should cause Karina to turn toward the northeast with some acceleration over the next few days, and eventually move northward to north-northwestward late in the period. The official forecast is a little slower than the dynamical model consensus, and similar to the latest Florida State University Superensemble track. FORECAST POSITIONS AND MAX WINDS INIT 21/1500Z 15.0N 136.9W 50 KT 60 MPH 12H 22/0000Z 14.8N 136.5W 50 KT 60 MPH 24H 22/1200Z 15.0N 135.9W 50 KT 60 MPH 36H 23/0000Z 15.6N 135.1W 45 KT 50 MPH 48H 23/1200Z 16.4N 134.0W 40 KT 45 MPH 72H 24/1200Z 18.5N 131.0W 35 KT 40 MPH 96H 25/1200Z 23.0N 129.0W 30 KT 35 MPH...POST-TROP/REMNT LOW 120H 26/1200Z 27.5N 131.5W 25 KT 30 MPH...POST-TROP/REMNT LOW $$ Forecaster Pasch

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Hurricane LOWELL Forecast Discussion Number 15

2014-08-21 16:32:39| Tropical Depression LIDIA

Issued at 800 AM PDT THU AUG 21 2014

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Tropical Storm LOWELL Forecast Discussion Number 14

2014-08-21 10:40:39| Tropical Depression LIDIA

Issued at 200 AM PDT THU AUG 21 2014

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Tropical Storm KARINA Forecast Discussion Number 34

2014-08-21 10:38:09| National Hurricane Center (East Pacific)

Issued at 200 AM PDT THU AUG 21 2014 000 WTPZ41 KNHC 210838 TCDEP1 TROPICAL STORM KARINA DISCUSSION NUMBER 34 NWS NATIONAL HURRICANE CENTER MIAMI FL EP112014 200 AM PDT THU AUG 21 2014 Karina is being affected by moderate-to-strong vertical wind shear, with the low-level center located on the northeastern edge of the deep convection. Subjective and objective T-numbers have decreased from 6 hours ago, and a blend of the T-numbers and CI numbers supports bringing the maximum winds down to 45 kt. Water vapor imagery shows an expansive area of dry mid-/upper-level air surging southward on the west side of Tropical Storm Lowell toward Karina. This flow will likely continue to disrupt Karina's structure during the next day or so, and drier air may also begin to infiltrate into the cyclone's circulation. In addition, Karina will be moving over sub-26C water in about 3 days. All these factors argue for little change in intensity during the next 48 hours, followed by weakening and degeneration to a remnant low by day 4. The updated NHC intensity forecast is a little lower than the previous one, mainly due to the lower initial intensity, and it is fairly close to the intensity consensus. Recent microwave images suggest that Karina has been drifting east-southeastward, and the initial motion estimate is 110/2 kt. The cyclone is likely to drift southeastward and east-southeastward for the next 24 hours. After that time, the distance between Karina and Lowell will be decreasing, and Karina will respond by accelerating northeastward and then northward around the east side of Lowell beyond 48 hours. The track guidance is in good agreement on this scenario, and no significant changes from the previous NHC forecast were required on this advisory. Although a 5-day point is given, Karina will likely be in the process of becoming absorbed by Lowell, and it is possible that a surface center may no longer exist at that time. FORECAST POSITIONS AND MAX WINDS INIT 21/0900Z 15.6N 136.2W 45 KT 50 MPH 12H 21/1800Z 15.3N 136.0W 45 KT 50 MPH 24H 22/0600Z 15.1N 135.5W 40 KT 45 MPH 36H 22/1800Z 15.6N 134.6W 40 KT 45 MPH 48H 23/0600Z 16.5N 133.5W 40 KT 45 MPH 72H 24/0600Z 18.5N 130.5W 35 KT 40 MPH 96H 25/0600Z 22.5N 128.5W 30 KT 35 MPH...POST-TROP/REMNT LOW 120H 26/0600Z 28.5N 131.5W 25 KT 30 MPH...POST-TROP/REMNT LOW $$ Forecaster Berg

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Tropical Storm KARINA Forecast Discussion Number 33

2014-08-21 04:47:06| National Hurricane Center (East Pacific)

Issued at 800 PM PDT WED AUG 20 2014 000 WTPZ41 KNHC 210247 TCDEP1 TROPICAL STORM KARINA DISCUSSION NUMBER 33 NWS NATIONAL HURRICANE CENTER MIAMI FL EP112014 800 PM PDT WED AUG 20 2014 After looking fairly robust on the previous advisory, 25-30 kt of vertical wind shear has left the convective cloud pattern looking rather disheveled over the past several hours. A 20/2318 UTC AMSU overpass indicated that the strong shear had displaced the mid-level circulation at least 45 nmi southwest of the now fully exposed low-level center. Satellite intensity estimates from both TAFB and SAB have decreased, yielding an average intensity estimate of 50 kt, which is the initial intensity used for this advisory. As expected, the steering currents have collapsed and Karina has been meandering in the same general area for the past 12 hours or so. Little motion is expected tonight, with a drift to the east or east-southeast forecast to begin on Thursday. After that, Karina is expected to begin moving slowly northeastward as it comes under the influence of the large circulation of Tropical Storm Lowell located well to the east of the cyclone. As the distance between the two systems decreases, smaller Karina is expected to accelerate northeastward and then northward within the eastern portion of Lowell's circulation, gradually getting drawn closer to the center of Lowell. NHC guidance remains in excellent agreement on this developing track scenario, and the official forecast is similar to but a little east of the consensus model TVCE in order to maintain a reasonable physical distance between the centers of the two tropical cyclones. Fluctuations in the amount of Lowell-induced shear that will affect Karina will also result in fluctuations in the cyclone's intensity for the 72 hours while it remains over 26C and warmer SSTs. But overall, no significant intensity changes are expected for the next 2 to 3 days. After that, however, increasing shear as Karina moves closer to Lowell's center, plus sharply decreasing sea-surface temperatures, will induce weakening on Days 4 and 5. Karina is expected to become a post-tropical remnant low pressure system by 96 hours, but given the rather small size of the cyclone, it is possible that the system could degenerate into an open trough as it interacts with the larger circulation of Tropical Storm Lowell. FORECAST POSITIONS AND MAX WINDS INIT 21/0300Z 15.9N 136.4W 50 KT 60 MPH 12H 21/1200Z 15.7N 136.3W 50 KT 60 MPH 24H 22/0000Z 15.5N 135.8W 50 KT 60 MPH 36H 22/1200Z 15.6N 135.1W 50 KT 60 MPH 48H 23/0000Z 16.3N 134.1W 50 KT 60 MPH 72H 24/0000Z 18.3N 131.0W 40 KT 45 MPH 96H 25/0000Z 21.4N 128.0W 30 KT 35 MPH...POST-TROP/REMNT LOW 120H 26/0000Z 27.0N 129.5W 25 KT 30 MPH...POST-TROP/REMNT LOW $$ Forecaster Stewart

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