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Tropical Depression ANA Forecast Discussion Number 12

2015-05-10 22:32:05| National Hurricane Center (Atlantic)

Issued at 500 PM EDT SUN MAY 10 2015 000 WTNT41 KNHC 102031 TCDAT1 TROPICAL DEPRESSION ANA DISCUSSION NUMBER 12 NWS NATIONAL HURRICANE CENTER MIAMI FL AL012015 500 PM EDT SUN MAY 10 2015 Surface and radar data indicate that Ana is moving farther inland. The estimated intensity is 30 kt, and these winds are confined to the coastal areas of North Carolina. Continued weakening is expected, and the system should degenerate into a post-tropical remnant low within 24 hours. Although a forecast track is shown through 48 hours, it should be noted that the global models show the system degenerating into an open trough sooner than that time. In any event, the remnants of Ana are likely to be absorbed by a larger extratropical cyclone over Atlantic Canada. The initial motion estimate is north-northeastward, or 020/4 kt. The steering flow associated with a large mid-level trough to the west of Ana should cause the cyclone to turn northeastward with some acceleration over the next day or two. The official track forecast lies between the dynamical model consensus and the latest ECMWF solution. This is the last advisory issued by the National Hurricane Center on Ana. Future information on this system can be found in Public Advisories issued by the Weather Prediction Center beginning at 11 PM EDT under AWIPS header TCPAT1 AND WMO header WTNT31 KWNH. FORECAST POSITIONS AND MAX WINDS INIT 10/2100Z 34.4N 78.6W 30 KT 35 MPH 12H 11/0600Z 35.3N 78.0W 25 KT 30 MPH...INLAND 24H 11/1800Z 37.0N 76.2W 25 KT 30 MPH...POST-TROP/REMNT LOW 36H 12/0600Z 39.3N 73.3W 25 KT 30 MPH...POST-TROP/REMNT LOW 48H 12/1800Z 42.0N 68.0W 25 KT 30 MPH...POST-TROP/REMNT LOW 72H 13/1800Z...ABSORBED $$ Forecaster Pasch

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Tropical Storm ANA Forecast Discussion Number 11

2015-05-10 16:47:03| National Hurricane Center (Atlantic)

Issued at 1100 AM EDT SUN MAY 10 2015 000 WTNT41 KNHC 101446 TCDAT1 TROPICAL STORM ANA DISCUSSION NUMBER 11 NWS NATIONAL HURRICANE CENTER MIAMI FL AL012015 1100 AM EDT SUN MAY 10 2015 NOAA Doppler radar, surface data and visible satellite imagery indicate that Ana continues to move over land near the South Carolina-North Carolina border. Surface observations suggest that the cyclone is barely of tropical storm intensity. Since the center is expected to be over land at least through tonight, weakening to a tropical depression is likely later today. Ana is forecast to move back over the Atlantic in about 36 hours, but regeneration after that time is unlikely due to cool waters and strong shear. The global models show the system degenerating into an open trough and becoming absorbed by a large mid-latitude low over Atlantic Canada in about 60 hours. Ana appears to have turned toward the north but the forward speed continues to be quite slow, around 4 kt. The flow ahead of a broad 500 mb trough should cause Ana or its remnant to turn toward the northeast with some acceleration over the next couple of days. The official track forecast is basically an update of the previous one, and is quite close to the latest dynamical model consensus, TVCN. Elevated water levels, high surf, and rip currents will continue to pose a threat over portions of the North and South Carolina coasts today. FORECAST POSITIONS AND MAX WINDS INIT 10/1500Z 34.1N 78.9W 35 KT 40 MPH 12H 11/0000Z 34.9N 78.5W 30 KT 35 MPH...INLAND 24H 11/1200Z 36.2N 77.3W 30 KT 35 MPH...INLAND 36H 12/0000Z 38.2N 75.1W 30 KT 35 MPH 48H 12/1200Z 41.0N 71.6W 30 KT 35 MPH...POST-TROP/REMNT LOW 72H 13/1200Z...DISSIPATED $$ Forecaster Pasch

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Tropical Storm ANA Forecast Discussion Number 10

2015-05-10 11:00:33| National Hurricane Center (Atlantic)

Issued at 500 AM EDT SUN MAY 10 2015 000 WTNT41 KNHC 100900 TCDAT1 TROPICAL STORM ANA DISCUSSION NUMBER 10 NWS NATIONAL HURRICANE CENTER MIAMI FL AL012015 500 AM EDT SUN MAY 10 2015 Satellite and radar data indicate that Ana's convective structure and organization have continued to increase since the previous advisory. Doppler radar data out of Wilmington, North Carolina (KLTX) indicate average velocities of around 60 kt just a few thousand a feet above the offshore waters, which would normally equate to 45-50 kt winds at the surface. However, observations from buoys, ships, and coastal surface stations indicate that the typically downward mixing of these stronger winds is not occurring due to the cooler shelf waters stabilizing the boundary layer. The initial intensity of 40 kt, which could be generous, is based on an earlier report of a 41-kt wind from Buoy 41013 during passage of a heavy rain band. Doppler radar data continue to indicate that Ana has been moving slowly north-northwestward at about 330/04 kt since the previous advisory. The cyclone should maintain this general motion this morning, and gradually turn more northward by this afternoon and evening. On Monday, an approaching large, deep-layer trough should turn Ana northeastward, accompanied by a marked increase in forward speed of about 12-15 kt. The NHC track forecast is essentially just an update of the previous advisory track and lies close to the TVCN consensus model. Cold shelf waters of 20-21C have taken their toll on Ana's surface wind field even though the convective banding has improved. Rapid weakening of the inner-core wind field should occur after the center of Ana moves inland. However, some strong rain bands accompanied by tropical-storm-force winds are expected to persist near and just offshore the North Carolina coast today, and that is the reason for keeping the system as a tropical storm for the next 12 hours or so. After that, slow weakening below tropical storm status is expected, although there could be gusts to tropical-storm-force in some of the heavier rain squalls over water. Ana is forecast to become a post-tropical low on Monday, and be absorbed by a larger extratropical low by Tuesday when the cyclone is near or east of the DelMarVa peninsula. The intensity forecast closely follows the Decay-SHIPS model. Since Ana is moving onshore, the reconnaissance flight originally scheduled for this morning has been canceled. Special thanks for the Air Force Reserve Hurricane Hunters for their flights into Ana owing to their limited resources during the pre-hurricane season. FORECAST POSITIONS AND MAX WINDS INIT 10/0900Z 33.8N 78.7W 40 KT 45 MPH 12H 10/1800Z 34.4N 78.7W 35 KT 40 MPH...INLAND 24H 11/0600Z 35.6N 77.9W 30 KT 35 MPH...INLAND 36H 11/1800Z 37.4N 76.3W 30 KT 35 MPH...INLAND 48H 12/0600Z 39.7N 73.4W 30 KT 35 MPH...POST-TROP/REMNT LOW 72H 13/0600Z...ABSORBED $$ Forecaster Stewart

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Tropical Storm ANA Forecast Discussion Number 9

2015-05-10 04:48:29| National Hurricane Center (Atlantic)

Issued at 1100 PM EDT SAT MAY 09 2015 000 WTNT41 KNHC 100248 TCDAT1 TROPICAL STORM ANA DISCUSSION NUMBER 9 NWS NATIONAL HURRICANE CENTER MIAMI FL AL012015 1100 PM EDT SAT MAY 09 2015 Satellite and radar data indicate that Ana's convective structure increased in organization during the late afternoon as banding increased over the northeastern portion of the circulation. However, during the past few hours, the cloud top temperatures have warmed and the convection has decreased in intensity. Data from an Air Force Reserve reconnaissance aircraft indicate that the initial intensity remains at 50 kt, which is in best agreement with uncontaminated SFMR winds. Ana is still forecast to weaken slightly while it moves over cooler waters near the coast overnight. Additional weakening should occur once the center moves onshore Sunday morning. The cyclone is forecast to become post-tropical on Monday before it is absorbed by a larger extratropical low over eastern North America. Radar data and aircraft fixes indicate that Ana is moving north- northwestward, or 320/04. The tropical cyclone should continue moving slowly north-northwestward tonight as a mid-tropospheric ridge to the north of Ana shifts eastward. A broad trough moving into the central and eastern U.S. during the next few days is expected to cause the cyclone or its remnants to turn northward on Sunday and then northeastward at a faster forward speed by Sunday night. The updated NHC track is similar to the previous advisory and is close to the multi-model consensus. FORECAST POSITIONS AND MAX WINDS INIT 10/0300Z 33.2N 78.3W 50 KT 60 MPH 12H 10/1200Z 33.8N 78.6W 45 KT 50 MPH...NEAR THE COAST 24H 11/0000Z 34.7N 78.4W 30 KT 35 MPH...INLAND 36H 11/1200Z 35.9N 77.3W 30 KT 35 MPH...INLAND 48H 12/0000Z 37.8N 75.0W 30 KT 35 MPH...POST-TROP/REMNT LOW 72H 13/0000Z...ABSORBED $$ Forecaster Brown

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Tropical Storm ANA Forecast Discussion Number 8

2015-05-09 22:35:27| National Hurricane Center (Atlantic)

Issued at 500 PM EDT SAT MAY 09 2015 000 WTNT41 KNHC 092035 TCDAT1 TROPICAL STORM ANA DISCUSSION NUMBER 8 NWS NATIONAL HURRICANE CENTER MIAMI FL AL012015 500 PM EDT SAT MAY 09 2015 Ana continues to maintain deep convection near and east of the center, although the convection is rather ragged-looking. There is weak upper-level outflow over the southern portion of the circulation. The current intensity is held at 50 kt, in agreement with data from an ASCAT overpass from several hours ago. Since the storm will be moving over progressively cooler waters as it departs the Gulf Stream, and is being influenced by northwesterly shear and some dry air, gradual weakening is forecast until landfall. After Ana crosses the coast, the weakening will of course be more rapid. The official intensity forecast is again close to IVCN, the intensity model consensus. Global model guidance indicates that Ana or its post-tropical remnant will become absorbed by, or merge with, a large extratropical cyclone over Atlantic Canada within 72 hours. The center is a little difficult to locate, but my best estimate of the initial motion is 320/3. The track forecast philosophy continues unchanged. The persistent mid-tropospheric blocking ridge to the north of Ana is predicted by the global models to shift eastward and weaken during the next day or so. The models also depict a broad trough moving eastward from the central to the eastern U.S. over the next 2-3 days. This evolution of the steering currents should cause Ana to turn northward and northeastward. The official track forecast is similar to the dynamical model consensus, IVCN, but leans a little more toward the latest ECMWF solution. FORECAST POSITIONS AND MAX WINDS INIT 09/2100Z 32.9N 78.3W 50 KT 60 MPH 12H 10/0600Z 33.4N 78.6W 45 KT 50 MPH 24H 10/1800Z 34.2N 78.7W 35 KT 40 MPH...INLAND 36H 11/0600Z 35.2N 78.1W 30 KT 35 MPH...INLAND 48H 11/1800Z 36.7N 76.5W 30 KT 35 MPH...INLAND 72H 12/1800Z...ABSORBED $$ Forecaster Pasch

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