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Hurricane Juliette Forecast Discussion Number 19
2019-09-05 22:33:56| National Hurricane Center (East Pacific)
Issued at 200 PM PDT Thu Sep 05 2019 000 WTPZ41 KNHC 052033 TCDEP1 Hurricane Juliette Discussion Number 19 NWS National Hurricane Center Miami FL EP112019 200 PM PDT Thu Sep 05 2019 Juliette's structure remains well defined in visible satellite imagery, with a lose banding eye evident. Recent microwaves images, however, indicate that there are some breaks in the band and that the eye is open to the southwest. An average of the latest Dvorak data-T and current intensity (CI) numbers from SAB and TAFB yields a 70 kt estimate, while a UW/CIMSS AMSU estimate indicates 75-kt, and the latter is the basis for the new advisory intensity. Juliette will be moving over decreasing sea surface temperatures and into a drier, and more stable air mass during the next few days. These unfavorable factors should result in gradual weakening of the hurricane. Increasing southwesterly shear by 72 hours is likely to cause a further demise of the cyclone, and Juliette is now anticipated to become post-tropical by day 3. Juliette is moving slightly faster toward the northwest or 305/10 kt. A northwestward to west-northwestward motion around the southwestern portion of a subtropical ridge should continue tonight and Saturday. After that time, a turn toward the west is expected as Juliette weakens and comes under the influence of the low-level easterly steering flow. Although the track guidance is in good agreement on this general scenario, there are some significant differences in the future forward speed of Juliette. Given this model spread, the NHC track prediction remains fairly close to the TVCE multi-model consensus. FORECAST POSITIONS AND MAX WINDS INIT 05/2100Z 21.3N 120.9W 75 KT 85 MPH 12H 06/0600Z 22.1N 122.3W 70 KT 80 MPH 24H 06/1800Z 23.0N 124.4W 60 KT 70 MPH 36H 07/0600Z 23.5N 126.4W 50 KT 60 MPH 48H 07/1800Z 23.8N 128.4W 45 KT 50 MPH 72H 08/1800Z 23.6N 132.2W 35 KT 40 MPH...POST-TROPICAL 96H 09/1800Z 23.3N 135.5W 30 KT 35 MPH...POST-TROP/REMNT LOW 120H 10/1800Z 23.2N 138.0W 25 KT 30 MPH...POST-TROP/REMNT LOW $$ Forecaster Brown
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Hurricane Dorian Forecast Discussion Number 49
2019-09-05 16:55:52| National Hurricane Center (Atlantic)
Issued at 1100 AM EDT Thu Sep 05 2019 000 WTNT45 KNHC 051455 TCDAT5 Hurricane Dorian Discussion Number 49 NWS National Hurricane Center Miami FL AL052019 1100 AM EDT Thu Sep 05 2019 The latest NOAA Doppler radar data, along with Air Force Reserve and NOAA Hurricane Hunter reports, indicate that Dorian has an well- defined eye with a diameter of about 40 n mi, with the northwestern edge of the eyewall not far from the South Carolina coast. The Hurricane Hunter data indicate that the flight-level and SFMR surface winds have decreased some since 12 h ago, accompanied by a rise in the central pressure. Based on this, the initial intensity is decreased to a possibly generous 95 kt. The central pressure of 958 mb is based partly on data from NOAA buoy 41004, which is currently inside the eye. Dorian has nudged eastward during the past several hours and the initial motion is now 020/7. The hurricane is now moving into the mid-latitude westerlies, and during the next several hours it is expected to turn northeastward with an increase in forward speed. This should bring the eye near or over the coasts of eastern South Carolina and southeastern North Carolina 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 72 h. The track guidance remains tightly clustered, and the new forecast track is changed little from the previous forecast. Dorian is forecast to slowly weaken as it moves along the South and North Carolina coasts. Extratropical transition should begin around 48 h and be complete by 72 h, although Dorian is forecast to maintain hurricane-force winds through the transition. After 72 h, the extratropical low should weaken over the far north Atlantic. 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. 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 will become more widespread across the eastern Carolinas and far southeast Virginia today into 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 05/1500Z 32.5N 79.1W 95 KT 110 MPH 12H 06/0000Z 33.5N 78.0W 90 KT 105 MPH 24H 06/1200Z 35.1N 75.8W 85 KT 100 MPH 36H 07/0000Z 37.2N 72.4W 80 KT 90 MPH 48H 07/1200Z 40.1N 68.0W 80 KT 90 MPH 72H 08/1200Z 48.0N 59.5W 65 KT 75 MPH...POST-TROP/EXTRATROP 96H 09/1200Z 54.5N 48.5W 50 KT 60 MPH...POST-TROP/EXTRATROP 120H 10/1200Z 59.5N 32.0W 40 KT 45 MPH...POST-TROP/EXTRATROP $$ Forecaster Beven
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Tropical Storm Gabrielle Forecast Discussion Number 8
2019-09-05 16:44:21| National Hurricane Center (Atlantic)
Issued at 1100 AM AST Thu Sep 05 2019 000 WTNT43 KNHC 051444 TCDAT3 Tropical Storm Gabrielle Discussion Number 8 NWS National Hurricane Center Miami FL AL082019 1100 AM AST Thu Sep 05 2019 Gabrielle is struggling due to persistent southeasterly shear. The low-level center is completely exposed and has become quite elongated, and the nearest deep convection is displaced almost 60 n mi to the north. And yet, ASCAT-A and B data at 1200 UTC revealed that the winds have not yet decreased. Both passes showed winds of 40-45 kt in the northwest quadrant of the cyclone, so the initial intensity is held at 45 kt. For the next 36 h or so, Gabrielle will remain in a very unfavorable environment, and the wind shear is actually expected to increase according to SHIPS diagnostics from the GFS and ECMWF models. Beyond that time, the shear is forecast to decrease and Gabrielle will have a window in which it could strengthen over the weekend. By early next week, the cyclone is expected to move over much colder SSTs and will likely begin the process of becoming post-tropical, so further strengthening is unlikely. The new NHC forecast is generally close to the previous one, but now allows for some slight short-term weakening of Gabrielle, given the hostile current environment. Almost no change was required to the track forecast, which is merely an update to the previous advisory. Gabrielle should move generally northwestward toward a weakness in the subtropical ridge for the next 3 or 4 days before it recurves ahead of a deep-layer mid-latitude trough approaching from the northwest by the end of the forecast period. The NHC forecast lies near the middle of the track guidance envelope. FORECAST POSITIONS AND MAX WINDS INIT 05/1500Z 22.8N 35.5W 45 KT 50 MPH 12H 06/0000Z 23.8N 36.4W 45 KT 50 MPH 24H 06/1200Z 25.5N 38.1W 40 KT 45 MPH 36H 07/0000Z 27.4N 40.0W 40 KT 45 MPH 48H 07/1200Z 29.4N 42.3W 45 KT 50 MPH 72H 08/1200Z 33.0N 47.0W 55 KT 65 MPH 96H 09/1200Z 37.0N 48.0W 60 KT 70 MPH 120H 10/1200Z 42.0N 42.5W 55 KT 65 MPH $$ Forecaster Zelinsky
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Hurricane Juliette Forecast Discussion Number 18
2019-09-05 16:42:24| National Hurricane Center (East Pacific)
Issued at 800 AM PDT Thu Sep 05 2019 000 WTPZ41 KNHC 051442 TCDEP1 Hurricane Juliette Discussion Number 18 NWS National Hurricane Center Miami FL EP112019 800 AM PDT Thu Sep 05 2019 There has been little overall change in Juliette's cloud pattern this morning. The hurricane still has a large, ragged eye, but the cloud tops within the surrounding ring of convection have warmed during the past couple of hours. Earlier microwave imagery showed a well-defined low-level eye that is located a little south of the satellite fixes from TAFB and SAB. The various satellite intensity estimates range from 77 to 85 kt, so the initial wind speed of 80 kt is maintained for this advisory. Juliette will be moving over gradually lower sea surface temperatures and into a more stable air mass but the vertical shear is expected to remain fairly low during the next couple days. This will likely result in a somewhat slower rate of weakening than is typical for east Pacific hurricanes moving over cool SSTs. Later in the period, southwesterly shear is expected to increase which should cause the cyclone to degenerate into a remnant low in 3 to 4 days. The NHC intensity foreast is closest to the SHIPS intensity model. The initial motion estimate is 305/8 kt. A general northwestward motion around the southwestern portion of the mid-level ridge over the southwestern United States should continue today. A turn toward the west-northwest, and then the west, is expected over the next couple of days as Juliette gradually weakens and is steered by the easterly low- to mid-level flow. The new NHC track forecast is near the middle of the guidance envelope but is a little faster than the previous advisory to be closer to the multi-model consensus aids. FORECAST POSITIONS AND MAX WINDS INIT 05/1500Z 20.6N 119.9W 80 KT 90 MPH 12H 06/0000Z 21.5N 121.3W 75 KT 85 MPH 24H 06/1200Z 22.6N 123.3W 65 KT 75 MPH 36H 07/0000Z 23.3N 125.4W 55 KT 65 MPH 48H 07/1200Z 23.6N 127.4W 45 KT 50 MPH 72H 08/1200Z 23.6N 131.2W 35 KT 40 MPH 96H 09/1200Z 23.2N 134.5W 30 KT 35 MPH...POST-TROP/REMNT LOW 120H 10/1200Z 23.0N 137.0W 25 KT 30 MPH...POST-TROP/REMNT LOW $$ Forecaster Brown
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Tropical Storm Gabrielle Forecast Discussion Number 7
2019-09-05 10:54:52| National Hurricane Center (Atlantic)
Issued at 500 AM AST Thu Sep 05 2019 000 WTNT43 KNHC 050854 TCDAT3 Tropical Storm Gabrielle Discussion Number 7 NWS National Hurricane Center Miami FL AL082019 500 AM AST Thu Sep 05 2019 METEOSAT imagery and an earlier WindSat microwave overpass show Gabielle's poorly defined center of circulation sheared well to the south of the curved convective band features to north, indicative of moderate southerly shear. The initial intensity is held at a generous 45 kt for this advisory, and is based on the subjective T-numbers from TAFB and SAB. Although Gabrielle could experience some intensity fluctuations during the next 24 hours, the cyclone should remain in a rather harsh environment during the next 36-48 hours, due to south to southwesterly vertical shear, some dry air in the middle portions of the atmosphere, and oceanic sea surface temperatures on the order of 25-26C. Afterward, gradual strengthening is forecast as Gabrielle moves into a more favorable upper wind pattern and warmer SSTs, and this is consistent with the IVCN multi-model consensus and the Decay SHIPS. After the adjustment to the south of the previous advisory based on the ASCAT-A/B scatterometer passes and a recent SSMI/S image, the initial motion is estimated to be northwestward, or 315/7 kt. For the next several days, Gabrielle is expected to move generally northwestward toward a large weakness in the mid-Atlantic subtropical ridge. An increase in forward motion is expected as the steering flow strengthens between a cut-off low to the west and high pressure to the northeast. Around days 4 and 5, the cyclone should turn generally northward in response to an approaching mid-tropospheric short wave trough. An adjustment to the right of the previous forecast was made, and the NHC forecast is based on a blend of the various consensus models. FORECAST POSITIONS AND MAX WINDS INIT 05/0900Z 21.9N 35.0W 45 KT 50 MPH 12H 05/1800Z 22.7N 35.8W 45 KT 50 MPH 24H 06/0600Z 24.2N 37.3W 45 KT 50 MPH 36H 06/1800Z 26.1N 39.1W 45 KT 50 MPH 48H 07/0600Z 28.0N 41.0W 45 KT 50 MPH 72H 08/0600Z 31.6N 46.1W 55 KT 65 MPH 96H 09/0600Z 35.8N 48.7W 60 KT 70 MPH 120H 10/0600Z 40.6N 44.7W 60 KT 70 MPH $$ Forecaster Roberts
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