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Hurricane CRISTOBAL Forecast Discussion Number 13

2014-08-26 22:46:12| National Hurricane Center (Atlantic)

Issued at 500 PM EDT TUE AUG 26 2014 000 WTNT44 KNHC 262046 TCDAT4 HURRICANE CRISTOBAL DISCUSSION NUMBER 13 NWS NATIONAL HURRICANE CENTER MIAMI FL AL042014 500 PM EDT TUE AUG 26 2014 As Cristobal has moved northward around the eastern side of the upper trough it is currently interacting with, the shear has decreased over the cyclone and deep convection has redeveloped near the center. The latest NOAA Hurricane Hunter aircraft found that the pressure had fallen to 984 mb and reported a partial eyewall. The initial intensity of 65 kt is based on a peak 8,000-ft flight-level wind of 75 kt and SFMR winds around 60 kt. Aircraft data and a partial ASCAT pass show that the wind field of Cristobal has expanded significantly in the eastern semicircle, and the initial and forecast wind radii have been adjusted outward. Conditions should be favorable for some strengthening as a tropical cyclone during the next couple of days before the cyclone moves over cooler waters and into a higher shear environment. After that time, the GFS, ECMWF, and UKMET all show an impressive extratropical transition of Cristobal, as it interacts synergistically with a powerful mid-latitude trough in about 3 days. This should result in Cristobal maintaining hurricane-force winds for a time as an extratropical cyclone. The initial motion estimate is 010/12. Cristobal jogged north- northeastward earlier today, but is now moving a bit more to the left. The dynamical model guidance shows a bit of a northward jog tonight as the cyclone moves east of the upper-trough. After that time an acceleration toward the northeast is expected as the subtropical ridge to the southeast propels Cristobal into the mid latitudes by 48 hours. A quick northeastward motion is expected to continue through 4 days with a bend back toward the north-northeast shown at day 5. The track model guidance has shifted a bit to the west this cycle in the short range, and the NHC forecast has been nudged in that direction for the first 36 hours, but lies on the east side of the guidance envelope. At 48 hours and beyond the NHC forecast is largely an update of the previous one and is close to a consensus of the GFS and ECMWF models. FORECAST POSITIONS AND MAX WINDS INIT 26/2100Z 28.8N 71.4W 65 KT 75 MPH 12H 27/0600Z 30.7N 71.2W 70 KT 80 MPH 24H 27/1800Z 32.9N 70.4W 70 KT 80 MPH 36H 28/0600Z 35.2N 67.6W 75 KT 85 MPH 48H 28/1800Z 38.0N 62.4W 75 KT 85 MPH 72H 29/1800Z 45.5N 47.0W 70 KT 80 MPH...POST-TROP/EXTRATROP 96H 30/1800Z 52.5N 35.0W 60 KT 70 MPH...POST-TROP/EXTRATROP 120H 31/1800Z 60.0N 26.0W 55 KT 65 MPH...POST-TROP/EXTRATROP $$ Forecaster Brennan

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Hurricane CRISTOBAL Forecast Discussion Number 12

2014-08-26 16:42:40| National Hurricane Center (Atlantic)

Issued at 1100 AM EDT TUE AUG 26 2014 000 WTNT44 KNHC 261442 TCDAT4 HURRICANE CRISTOBAL DISCUSSION NUMBER 12 NWS NATIONAL HURRICANE CENTER MIAMI FL AL042014 1100 AM EDT TUE AUG 26 2014 The center of Cristobal is partially exposed to the northwest of the deep convection. Analyses from UW-CIMSS and the SHIPS model show about 20 kt of west-northwesterly shear over Cristobal and dry air has wrapped into the southwestern quadrant of the circulation as the cyclone interacts with a mid/upper-level trough to its west. The initial intensity remains 65 kt based on data from the last NOAA Hurricane Hunter aircraft mission. Model guidance indicates that the upper-level winds will become less hostile during the next day or so as Cristobal moves underneath and then north of the aforementioned trough, which should allow for some intensification. The NHC forecast shows Cristobal peaking in 36-48 hours in agreement with the latest IVCN intensity consensus. After that time, Cristobal will be moving over cooler waters and into a higher shear environment, which should result in the system losing tropical characteristics in about 3 days. However, as this occurs the global models show Cristobal moving in a favorable position for baroclinic intensification ahead of a mid-latitude trough. This should result in Cristobal transitioning to a powerful extratropical cyclone over the north Atlantic late in the period. The initial motion estimate is 010/10, as Cristobal is currently being pulled slowly northward by the mid/upper-level trough situated east of Florida. During the next day or so Cristobal will begin moving north-northeastward around the western side of the Atlantic subtropical ridge. Then the cyclone should accelerate into the mid-latitude westerlies during the remainder of the forecast period. Overall, the track model guidance remains in good agreement on this scenario. The new NHC track has been shifted a little to the west, or left, of the previous one through 48 hours and lies along the eastern edge of the guidance envelope. After that time, the NHC forecast is largely an update of the previous one and is close to the multi-model consensus. FORECAST POSITIONS AND MAX WINDS INIT 26/1500Z 27.2N 71.7W 65 KT 75 MPH 12H 27/0000Z 29.4N 71.3W 70 KT 80 MPH 24H 27/1200Z 31.9N 70.7W 70 KT 80 MPH 36H 28/0000Z 33.9N 69.1W 75 KT 85 MPH 48H 28/1200Z 36.4N 65.1W 75 KT 85 MPH 72H 29/1200Z 43.0N 51.5W 65 KT 75 MPH...POST-TROPICAL 96H 30/1200Z 50.0N 37.0W 60 KT 70 MPH...POST-TROP/EXTRATROP 120H 31/1200Z 58.0N 26.0W 50 KT 60 MPH...POST-TROP/EXTRATROP $$ Forecaster Brennan

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Hurricane MARIE Forecast Discussion Number 19

2014-08-26 16:36:41| National Hurricane Center (East Pacific)

Issued at 800 AM PDT TUE AUG 26 2014 000 WTPZ43 KNHC 261436 TCDEP3 HURRICANE MARIE DISCUSSION NUMBER 19 NWS NATIONAL HURRICANE CENTER MIAMI FL EP132014 800 AM PDT TUE AUG 26 2014 Microwave data show that Marie continues to have a complicated inner core structure, with an remnant inner eyewall surrounded by a pair of larger concentric eyewall rings. Dvorak estimates are still falling, so the initial intensity is lowered to 85 kt. Steady-to-rapid weakening of Marie is expected with the cyclone now crossing the 26.5C isotherm into much colder waters. The intensity forecast is a blend of the previous NHC prediction, the intensity consensus and the Florida State Superensemble. Marie should become a non-convective post-tropical cyclone in about 2 days when it moves over waters colder than 23C, although there will likely still be gale-force winds for some time after the transition. The initial motion is 300/13 kt. Model guidance is in excellent agreement on a west-northwestward to northwestward motion during the next few days while the system remains steered by mid-level ridging to its northeast. Marie should slow and turn toward the north-northwest by day 4 due to it reaching the western periphery of the ridge. The remnants of the cyclone are then expected to drift westward after that time within an area of light steering. Only a small southwestward adjustment has been made to the official forecast at long range to come into better agreement with the consensus models. Very large southerly swells continue to affect much of the Baja California peninsula, and will soon reach the southern California coast. These swells are expected to persist for a couple of days, and could produce life-threatening surf and rip currents, as well as minor coastal flooding around the time of high tide. FORECAST POSITIONS AND MAX WINDS INIT 26/1500Z 20.7N 119.0W 85 KT 100 MPH 12H 27/0000Z 21.6N 120.8W 70 KT 80 MPH 24H 27/1200Z 22.6N 123.3W 60 KT 70 MPH 36H 28/0000Z 23.7N 125.8W 50 KT 60 MPH 48H 28/1200Z 25.1N 128.3W 40 KT 45 MPH...POST-TROPICAL 72H 29/1200Z 28.1N 131.8W 35 KT 40 MPH...POST-TROPICAL 96H 30/1200Z 30.5N 133.0W 30 KT 35 MPH...POST-TROP/REMNT LOW 120H 31/1200Z 30.5N 133.5W 25 KT 30 MPH...POST-TROP/REMNT LOW $$ Forecaster Blake

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Hurricane MARIE Forecast Discussion Number 18

2014-08-26 10:38:38| National Hurricane Center (East Pacific)

Issued at 200 AM PDT TUE AUG 26 2014 000 WTPZ43 KNHC 260838 TCDEP3 HURRICANE MARIE DISCUSSION NUMBER 18 NWS NATIONAL HURRICANE CENTER MIAMI FL EP132014 200 AM PDT TUE AUG 26 2014 Microwave images indicate that Marie still has a double eyewall structure, though the outer eyewall is open on the north side. The eye of the hurricane remains fairly distinct in satellite images, but deep convection is not as intense as it was earlier. The initial intensity is lowered to 90 kt, following the Dvorak CI-numbers from TAFB and SAB. An ASCAT pass around 0500 UTC indicated that despite the weakening, the wind field of Marie remains very large. The hurricane is moving across a sharp sea surface temperature gradient, and it is expected to cross the 26 degree C isotherm later today. These cold waters, combined with a drier and more stable air mass, should cause Marie to continue weakening at a steady pace. The NHC intensity forecast is an update of the previous one and shows Marie becoming a post-tropical cyclone by 72 hours when it is expected to be over water temperatures below 23 C. Marie is moving northwestward at 12 kt. A west-northwestward to northwestward motion at about the same forward speed is forecast during the next few days while the system remains steered by mid-level ridging to its northeast. A slow down and turn toward the north-northwest is expected by the end of the forecast period when the weak system is steered by the lighter low-level flow. The NHC track forecast is nudged to the south this cycle, toward the latest consensus aids. Very large southerly swells continue to affect much of the Baja California peninsula, and will soon reach the southern California coast. These swells are expected to persist for a couple of days, and could produce life-threatening surf and rip currents, as well as minor coastal flooding. FORECAST POSITIONS AND MAX WINDS INIT 26/0900Z 19.9N 117.8W 90 KT 105 MPH 12H 26/1800Z 20.9N 119.5W 75 KT 85 MPH 24H 27/0600Z 21.9N 121.8W 60 KT 70 MPH 36H 27/1800Z 22.9N 124.4W 50 KT 60 MPH 48H 28/0600Z 24.2N 126.8W 40 KT 45 MPH 72H 29/0600Z 27.3N 130.8W 35 KT 40 MPH...POST-TROPICAL 96H 30/0600Z 29.9N 132.6W 30 KT 35 MPH...POST-TROP/REMNT LOW 120H 31/0600Z 30.5N 133.2W 25 KT 30 MPH...POST-TROP/REMNT LOW $$ Forecaster Cangialosi

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Tropical Depression KARINA Forecast Discussion Number 54

2014-08-26 10:37:39| National Hurricane Center (East Pacific)

Issued at 200 AM PDT TUE AUG 26 2014 000 WTPZ41 KNHC 260837 TCDEP1 TROPICAL DEPRESSION KARINA DISCUSSION NUMBER 54 NWS NATIONAL HURRICANE CENTER MIAMI FL EP112014 200 AM PDT TUE AUG 26 2014 Karina continues to produce sufficient organized convection to be considered a tropical cyclone despite ongoing easterly vertical wind shear caused by the upper-level outflow from Hurricane Marie. The initial intensity remains 30 kt, in agreement with a partial ASCAT pass and satellite intensity estimates from TAFB and SAB. Due to the ongoing shear, Karina is expected to degenerate into a remnant low soon, and then be absorbed into the much larger Marie in 24 hours or so. The initial motion is 100/3. The cyclone is embedded in westerly flow feeding into Marie, and a general east-southeastward motion with some increase in forward speed is expected until the cyclone is absorbed. FORECAST POSITIONS AND MAX WINDS INIT 26/0900Z 17.0N 127.1W 30 KT 35 MPH 12H 26/1800Z 16.6N 126.2W 25 KT 30 MPH...POST-TROP/REMNT LOW 24H 27/0600Z...ABSORBED BY HURRICANE MARIE $$ Forecaster Beven

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