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Hurricane Dorian Forecast Discussion Number 51

2019-09-06 04:54:02| National Hurricane Center (Atlantic)

Issued at 1100 PM EDT Thu Sep 05 2019 000 WTNT45 KNHC 060253 TCDAT5 Hurricane Dorian Discussion Number 51 NWS National Hurricane Center Miami FL AL052019 1100 PM EDT Thu Sep 05 2019 Data from NOAA and Air Force Hurricane Hunter planes and surface data nearby Dorian indicate that although the central pressure is a little bit lower, and NOAA Doppler weather radar data from Wilmington and Morehead City indicate that winds have decreased as the circulation of the hurricane expands. The initial intensity is now estimated to be 85 kt. Dorian is moving toward higher shear, and gradual weakening is anticipated. As indicated in the previous forecast, extratropical transition should begin in about 48 hours and be complete by 72 hours. However, Dorian is forecast to maintain hurricane-force-winds while moving near or over Nova Scotia. The initial motion is 045 degrees at 11 kt. The hurricane is already embedded in the southwesterly flow ahead of an eastward moving mid-latitude trough. This flow pattern should steer the hurricane on a northeastward track with increasing forward speed. Track guidance continues to be in remarkably good agreement with this solution, and the NHC forecast remains in the middle of the guidance envelope. The current forecast track is very similar to the previous advisory. The center of Dorian is expected to move very near or over the coastline of eastern North Carolina and the southern Mid-Atlantic states during the next day or so. Residents of these areas should already be prepared for damaging winds, life-threatening storm surges, and flooding rains. It also appears that Dorian will affect portions of eastern Canada with hurricane-force winds. Key Messages: 1. Regardless of the exact track of Dorian's core, life-threatening storm surge and dangerous winds are expected along portions of the North Carolina coast, portions of southeast Virginia and the southern Chesapeake Bay. Water levels could rise well in advance of the arrival of strong winds. Residents in these areas should follow advice given by local emergency officials. 2. Flash flooding is occurring, and will continue to become more widespread across the eastern Carolinas and far southeast Virginia overnight. There is a high risk of flash flooding over these areas, where significant, life-threatening flash flooding is expected. FORECAST POSITIONS AND MAX WINDS INIT 06/0300Z 33.8N 77.4W 85 KT 100 MPH 12H 06/1200Z 35.0N 75.8W 80 KT 90 MPH 24H 07/0000Z 37.2N 72.2W 80 KT 90 MPH 36H 07/1200Z 40.2N 67.7W 75 KT 85 MPH 48H 08/0000Z 44.5N 63.0W 70 KT 80 MPH 72H 09/0000Z 52.5N 55.0W 45 KT 50 MPH...POST-TROP/EXTRATROP 96H 10/0000Z 57.5N 40.0W 40 KT 45 MPH...POST-TROP/EXTRATROP 120H 11/0000Z...DISSIPATED $$ Forecaster Avila

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Hurricane Juliette Forecast Discussion Number 20

2019-09-06 04:50:00| National Hurricane Center (East Pacific)

Issued at 800 PM PDT Thu Sep 05 2019 000 WTPZ41 KNHC 060249 TCDEP1 Hurricane Juliette Discussion Number 20 NWS National Hurricane Center Miami FL EP112019 800 PM PDT Thu Sep 05 2019 Juliette has remained resilient despite moving over SSTs around 25-26C over the past several hours. Deep convection continues to envelop the center with a ragged eye apparent in both visible and infrared satellite imagery. The latest subjective Dvorak estimates from both TAFB and SAB suggest that the initial intensity remains at 75 kt. The cyclone will be moving over cooler waters of 24-25C tonight and tomorrow, and will remain over these water temperatures for the next several days. This should cause Juliette to slowly weaken. After 48 hours, southwesterly shear is expected to begin to impact Juliette's circulation. The combination of the cooler waters and shear should cause Juliette to become a post-tropical remnant low by 72 hours. The official forecast is very similar to the previous one, and near the various intensity consensus aids. Juliette's initial motion is 305/10 kt. A turn to the west-northwest is expected on Friday as the cyclone is steered by a subtropical ridge to its north. As the cyclone weakens and becomes steered by the low-level flow, a turn to the west is expected. The only notable change to the new official forecast track was a slight increase in forward speed beyond 48 hours, as the consensus aids have come into a little better agreement on a faster forward motion during that time period. FORECAST POSITIONS AND MAX WINDS INIT 06/0300Z 21.8N 121.8W 75 KT 85 MPH 12H 06/1200Z 22.6N 123.2W 70 KT 80 MPH 24H 07/0000Z 23.3N 125.3W 60 KT 70 MPH 36H 07/1200Z 23.7N 127.4W 50 KT 60 MPH 48H 08/0000Z 23.7N 129.4W 45 KT 50 MPH 72H 09/0000Z 23.5N 133.3W 35 KT 40 MPH...POST-TROP/REMNT LOW 96H 10/0000Z 23.3N 136.5W 30 KT 35 MPH...POST-TROP/REMNT LOW 120H 11/0000Z 23.6N 139.5W 25 KT 30 MPH...POST-TROP/REMNT LOW $$ Forecaster Latto

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Tropical Storm Gabrielle Forecast Discussion Number 10

2019-09-06 04:35:03| National Hurricane Center (Atlantic)

Issued at 1100 PM AST Thu Sep 05 2019 000 WTNT43 KNHC 060234 TCDAT3 Tropical Storm Gabrielle Discussion Number 10 NWS National Hurricane Center Miami FL AL082019 1100 PM AST Thu Sep 05 2019 The center of Gabrielle has been devoid of deep convection since late this morning, as dry air and southerly shear have taken their toll. If this trend continues, then advisories may be discontinued Friday morning. For the time being, a recent scatterometer pass showed that 35 kt winds are still occurring in association with Gabrielle's circulation, and that will be the initial intensity for this advisory. SHIPS intensity guidance indicates strong shear will continue to affect the cyclone for the next 24 to 36 hours. If the circulation survives this, the shear will diminish. However, it appears that there will still be dry air to contend with. The forecast calls for a steady intensity through 36 hours, followed by slow strengthening as the shear becomes negligible. Late in the forecast period, the cyclone will move over cooler waters as it begins to transition to an extratropical cyclone, which should limit any non-baroclinic intensification beyond 96 hours. The intensity forecast is highly uncertain, as Gabrielle very well could become a post-tropical remnant low tomorrow. The convection will have to recover once the wind shear subsides, and I am skeptical that this will do so with any haste due to the dry air that is forecast to be in place. The official intensity forecast is similar to the previous one, and is below the various consensus aids beyond 36 hours. Gabrielle has begun to accelerate to the northwest. The forward speed will increase a little more through Friday morning as the cyclone is steered between a mid- to upper-level low to its west, and a subtropical ridge to its east. Later in the forecast period, Gabrielle will begin to turn northward then northeastward and accelerate as a mid-latitude trough approaches the cyclone. The official track forecast is very close to the previous one through 72 hours, and then was nudged slightly to the left beyond that time due to a shift in the global models and consensus guidance. FORECAST POSITIONS AND MAX WINDS INIT 06/0300Z 24.3N 36.6W 35 KT 40 MPH 12H 06/1200Z 25.7N 38.0W 35 KT 40 MPH 24H 07/0000Z 27.9N 40.2W 35 KT 40 MPH 36H 07/1200Z 29.7N 42.7W 40 KT 45 MPH 48H 08/0000Z 31.1N 45.3W 45 KT 50 MPH 72H 09/0000Z 34.3N 48.2W 55 KT 65 MPH 96H 10/0000Z 38.5N 45.5W 60 KT 70 MPH 120H 11/0000Z 44.5N 38.0W 60 KT 70 MPH $$ Forecaster Latto

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Hurricane Dorian Forecast Discussion Number 50

2019-09-05 22:51:25| National Hurricane Center (Atlantic)

Issued at 500 PM EDT Thu Sep 05 2019 931 WTNT45 KNHC 052051 TCDAT5 Hurricane Dorian Discussion Number 50 NWS National Hurricane Center Miami FL AL052019 500 PM EDT Thu Sep 05 2019 During the last 12 h, Dorian appears to have started the expected slow weakening trend. Air Force Reserve Hurricane Hunter data show that the central pressure inside the 35-45 n mi wide eye is slowly rising, and satellite imagery indicates that the eye is becoming less well defined. The current Hurricane Hunter aircraft has reported maximum SFMR surface wind estimates of 88 kt, along with 700 mb flight-level winds of 91 kt. Based on these data, the initial intensity is reduced to 90 kt. The hurricane is continuing its expected northeastward turn, and the initial motion is now 035/9. The mid-latitude westerlies should steer Dorian generally northeastward at an increasing forward speed, with the eye passing near of over portions of the North Carolina coast during the next 12-24 h. After that, Dorian is forecast to move quickly across the northwest Atlantic and be near or over the Canadian Maritimes/Atlantic provinces by 60 h. As was the case in the previous advisory, the track guidance remains tightly clustered, and the new forecast track is changed little from the previous one. Due to increasing shear, Dorian is forecast to slowly weaken as it moves near and along the South and North Carolina coasts. Extratropical transition should begin around 36-48 h and be complete by 60 h, although Dorian is forecast to maintain hurricane-force winds through the transition. After transition is complete, the extratropical low should weaken over the far north Atlantic and be absorbed into a larger low pressure area by 120 h. The center of Dorian is expected to move very near or over the coastline of the Carolinas and the southern Mid-Atlantic states. Residents of these areas should already be prepared for damaging winds, life-threatening storm surges, and flooding rains. It also appears that Dorian will affect portion of eastern Canada as a hurricane-force extratropical low. Key Messages: 1. Life-threatening storm surge and dangerous winds are expected along portions the coasts of South Carolina and North Carolina, and portions of southeast Virginia and the southern Chesapeake Bay, regardless of the exact track of Dorian's center. Water levels could rise well in advance of the arrival of strong winds. Residents in these areas should follow advice given by local emergency officials. 2. Flash flooding is occurring, and will continue to become more widespread across the eastern Carolinas and far southeast Virginia through tonight. There is a high risk of flash flooding over these areas, where significant, life-threatening, flash flooding is expected. FORECAST POSITIONS AND MAX WINDS INIT 05/2100Z 33.1N 78.5W 90 KT 105 MPH 12H 06/0600Z 34.2N 77.2W 90 KT 105 MPH 24H 06/1800Z 36.0N 74.4W 85 KT 100 MPH 36H 07/0600Z 38.5N 70.4W 80 KT 90 MPH 48H 07/1800Z 42.0N 65.9W 75 KT 85 MPH 72H 08/1800Z 50.0N 57.5W 65 KT 75 MPH...POST-TROP/EXTRATROP 96H 09/1800Z 56.0N 45.5W 50 KT 60 MPH...POST-TROP/EXTRATROP 120H 10/1800Z...DISSIPATED $$ Forecaster Beven

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Tropical Storm Gabrielle Forecast Discussion Number 9

2019-09-05 22:34:56| National Hurricane Center (Atlantic)

Issued at 500 PM AST Thu Sep 05 2019 000 WTNT43 KNHC 052034 TCDAT3 Tropical Storm Gabrielle Discussion Number 9 NWS National Hurricane Center Miami FL AL082019 500 PM AST Thu Sep 05 2019 Gabrielle is barely holding on to its status as a tropical cyclone. The closest deep convection is now displaced over 100 n mi to the north of the tropical storm's low-level center, and Dvorak intensity estimates have continued to decrease quickly. Given the lack of deep convection where the strongest winds were observed in earlier ASCAT data (not to mention near the cyclone's center), some weakening has likely occurred since then. The intensity is therefore set at 40 kt for this advisory. Very high shear should continue for the next 24 to 36 hours, and it is unlikely that Gabrielle will become any better organized during that period. In fact, it can not be ruled out that the cyclone could briefly become post-tropical due to a lack of deep convection during that period. However, the shear should decrease in a couple of days, and the cyclone will then be moving over very warm SSTs. Deep convection will likely increase over the weekend and some strengthening is still forecast thereafter. Most of the dynamical models even suggest that Gabrielle could become a hurricane before it starts to become extratropical sometime next week. The statistical guidance isn't nearly as bullish, so the NHC forecast continues to show only slow strengthening through the end of the forecast period. The tropical storm has slowed in the short term, but is forecast by all of the guidance to accelerate northwestward overnight. The models remain in very good agreement that Gabrielle will then continue northwestward for a few days before recurving early next week ahead of a deep-layer mid-latitude trough. Once again, little change has been made to the NHC track forecast which is very close to the multi-model consensus at every forecast hour. FORECAST POSITIONS AND MAX WINDS INIT 05/2100Z 23.4N 35.9W 40 KT 45 MPH 12H 06/0600Z 24.6N 37.0W 40 KT 45 MPH 24H 06/1800Z 26.6N 39.0W 40 KT 45 MPH 36H 07/0600Z 28.5N 41.2W 40 KT 45 MPH 48H 07/1800Z 30.2N 43.7W 45 KT 50 MPH 72H 08/1800Z 33.3N 48.0W 55 KT 65 MPH 96H 09/1800Z 37.5N 47.0W 60 KT 70 MPH 120H 10/1800Z 43.0N 40.0W 60 KT 70 MPH $$ Forecaster Zelinsky

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