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Tropical Storm FAY Forecast Discussion Number 9

2014-10-12 10:55:50| National Hurricane Center (Atlantic)

Issued at 500 AM AST SUN OCT 12 2014 000 WTNT42 KNHC 120855 TCDAT2 TROPICAL STORM FAY DISCUSSION NUMBER 9 NWS NATIONAL HURRICANE CENTER MIAMI FL AL072014 500 AM AST SUN OCT 12 2014 The area of cold cloud tops associated with Fay has expanded overnight, but radar imagery from Bermuda indicate that the overall convective structure of the cyclone has not changed much. Surface observations and the radar data show that the center of Fay has passed over the island within the past hour. Subsequently, a minimum pressure of 986 mb was reported at Bermuda airport observing station. The initial wind speed remains 60 kt and is based on the earlier aircraft and ASCAT data, and the 06z Dvorak classifications from SAB and TAFB. Little change in strength is expected during the next 12 to 24 hours. After that time, Fay is expected to merge with a frontal zone and become extratropical. The global models now keep the post-tropical cyclone a distinct feature along the frontal zone a little longer, so the new NHC forecast delays dissipation until around 48 hours. Fay has not turned quite as sharp as predicted. The initial motion estimate is north-northeastward or 015/17 kt. Fay should turn northeastward later this morning, and then accelerate north-northeastward in the mid-latitude westerly flow over the Atlantic tonight through Monday. The updated NHC track is a little north of the previous track and near the middle of the tightly clustered guidance models. FORECAST POSITIONS AND MAX WINDS INIT 12/0900Z 32.4N 64.6W 60 KT 70 MPH 12H 12/1800Z 34.2N 61.1W 60 KT 70 MPH 24H 13/0600Z 35.8N 55.2W 55 KT 65 MPH...POST-TROP/EXTRATROP 36H 13/1800Z 36.0N 49.0W 45 KT 50 MPH...POST-TROP/EXTRATROP 48H 14/0600Z...DISSIPATED $$ Forecaster Brown

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Tropical Storm FAY Forecast Discussion Number 7

2014-10-11 22:42:20| National Hurricane Center (Atlantic)

Issued at 500 PM AST SAT OCT 11 2014 000 WTNT42 KNHC 112042 TCDAT2 TROPICAL STORM FAY DISCUSSION NUMBER 7 NWS NATIONAL HURRICANE CENTER MIAMI FL AL072014 500 PM AST SAT OCT 11 2014 Tropical Storm Fay remains a sheared tropical cyclone with deep convection persisting in the northwestern quadrant. A 1442 UTC ASCAT-B overpass indicated several 50-52 kt surface wind vectors in the northeastern and northwestern quadrants, and buoy 41936 measured a pressure of 990.2 mb a few hours ago when the center passed just to its west. The initial intensity is being maintained at 60 kt for this advisory given that the buoy pressure was similar to the last recon reported surface pressure, and assuming that there is some undersampling by the ASCAT instrument. An Air Force Reserve reconnaissance aircraft is scheduled to investigate the cyclone around 0000 UTC this evening. The initial motion estimate is 360/16 kt, based in large part on scatterometer and microwave satellite fixes. Fay is expected to continue moving northward around a deep-layer ridge this evening, and then turn toward the north-northeast by 0600 UTC, passing just to the southeast of Bermuda at that time. However, only a slight deviation to the west of the forecast track would bring the center and core of strongest winds very close to or even over Bermuda, and for that reason the Bermuda Weather Service has issued a hurricane watch for the island. By 24 hours, Fay is expected to get caught up in the mid-latitude westerlies and recurve rapidly to the northeast or east-northeast before it merges with a frontal system by 48 hours. The new NHC guidance has again shifted a little to the left, and the official forecast track has been shifted slightly westward through 12 hours, and closely follows the multi-model consensus TVCN. Overall, there is no significant change to the previous intensity forecast or reasoning. However, the current south-southeasterly vertical wind shear of 32 kt is forecast by the GFS-based SHIPS model to decrease to around 25 kt from the south-southwest in 12-18 hours, which could allow for some slight strengthening during the convective maximum period around 0600 UTC tonight, and it is possible that Fay could briefly reach hurricane status. After 24 hours, the wind shear is forecast to increase to more than 40 kt from the southwest, which should induce a weakening trend up until the time that Fay merges with a strong frontal system by 48 hours. FORECAST POSITIONS AND MAX WINDS INIT 11/2100Z 29.5N 65.4W 60 KT 70 MPH 12H 12/0600Z 31.7N 64.4W 60 KT 70 MPH 24H 12/1800Z 33.7N 61.2W 60 KT 70 MPH 36H 13/0600Z 34.8N 56.2W 55 KT 65 MPH 48H 13/1800Z...ABSORBED BY FRONTAL SYSTEM $$ Forecaster Stewart

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Tropical Storm FAY Forecast Discussion Number 6

2014-10-11 16:54:47| National Hurricane Center (Atlantic)

Issued at 1100 AM AST SAT OCT 11 2014 000 WTNT42 KNHC 111454 TCDAT2 TROPICAL STORM FAY DISCUSSION NUMBER 6 NWS NATIONAL HURRICANE CENTER MIAMI FL AL072014 1100 AM AST SAT OCT 11 2014 Tropical Storm Fay made the transition to a tropical cyclone around 0600 UTC based on AMSU and other satellite data that arrived after the previous advisory was released. An Air Force Reserve reconnaissance aircraft confirmed this transition had occurred, when it made a pass through the northwestern and northern quadrants indicating that the radius of maximum wind had decreased to about 40 n mi. A blend of satellite intensity estimates, flight-level surface wind conversions, and reliable SFMR surface winds support increasing the intensity to 60 kt. The latest center dropsonde data suggests a central pressure of about 991 mb. The initial motion estimate is 355/14. Other than the center redeveloping a little farther west and closer to the deep convection, the overall track forecast and reasoning remains unchanged form the previous advisory. Fay is expected to continue to move northward and then northeastward around the western periphery of a strong mid-level ridge for the next 24 hours or so, and then recurve into the mid-latitude westerlies with an increase in forward speed by 36 hours. The official track forecast closely follows the multi-model consensus TVCN. The strength and direction of the current vertical wind shear is forecast to remain unchanged for the next 24 hours, so no change in intensity indicated during that time. By 36 hours, the shear is forecast to increase to more than 40 kt from the southwest, which should induce a weakening trend until the cyclone is absorbed by a strong cold front in about 48 hours. FORECAST POSITIONS AND MAX WINDS INIT 11/1500Z 27.9N 65.3W 60 KT 70 MPH 12H 12/0000Z 30.1N 65.2W 60 KT 70 MPH 24H 12/1200Z 33.0N 62.7W 60 KT 70 MPH 36H 13/0000Z 35.3N 58.0W 55 KT 65 MPH 48H 13/1200Z...ABSORBED BY FRONTAL SYSTEM $$ Forecaster Stewart

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Subtropical Storm FAY Forecast Discussion Number 5

2014-10-11 10:35:14| National Hurricane Center (Atlantic)

Issued at 500 AM AST SAT OCT 11 2014 000 WTNT42 KNHC 110835 TCDAT2 SUBTROPICAL STORM FAY DISCUSSION NUMBER 5 NWS NATIONAL HURRICANE CENTER MIAMI FL AL072014 500 AM AST SAT OCT 11 2014 It appears that Fay is gradually acquiring tropical characteristics as the convection becomes more symmetric and getting closer to the center, but it is not quite tropical yet. There is a small window of opportunity for Fay to transition to a tropical cyclone during the next 6 to 12 hours before the shear increases further. There is no data to change the winds at this time, and the initial intensity is kept at 50 kt. Another reconnaissance flight is scheduled for later this morning. Only a slight strengthening is anticipated before the system becomes absorbed by a strong cold front in about 48 hours as indicated by most of the global models. The initial motion estimate is 355/10. Fay continues to move around the western periphery of a mid-level ridge, and is expected to continue northward for 6 to 12 more hours. It should then recurve into the mid-latitude westerlies with an increase in forward speed. The NHC track forecast is similar to the previous one, and follows very closely the multi-model consensus TVCN. FORECAST POSITIONS AND MAX WINDS INIT 11/0900Z 26.7N 64.7W 50 KT 60 MPH 12H 11/1800Z 29.1N 64.7W 55 KT 65 MPH 24H 12/0600Z 32.2N 63.4W 55 KT 65 MPH 36H 12/1800Z 35.0N 59.0W 50 KT 60 MPH 48H 13/0600Z...DISSIPATED $$ Forecaster Avila

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Subtropical Storm FAY Forecast Discussion Number 4

2014-10-11 04:31:45| National Hurricane Center (Atlantic)

Issued at 1100 PM AST FRI OCT 10 2014 000 WTNT42 KNHC 110231 TCDAT2 SUBTROPICAL STORM FAY DISCUSSION NUMBER 4 NWS NATIONAL HURRICANE CENTER MIAMI FL AL072014 1100 PM AST FRI OCT 10 2014 The cloud pattern of Fay features an area of deep convection displaced northwest of the low-level center by about 30 kt of southerly shear and a fractured convective band well east of the center. The initial intensity remains 50 kt based on the earlier aircraft data. Overall, the cloud pattern looks more tropical than it did a few hours ago, and Fay will likely transition to a tropical cyclone in the next 6 to 12 hours. Given that the shear is expected to continue, only limited intensification is shown in the next 12 to 24 hours, followed by slow weakening until the cyclone is absorbed after 48 hours. The new NHC intensity forecast is close to the latest IVCN multi-model consensus. The initial motion estimate is 345/11, as Fay continues to move around the western periphery of a mid-level ridge. There is no change to the track forecast philosophy, with Fay expected to turn northward in the next 12 to 24 hours and then recurve into the mid-latitude westerlies. The new NHC track forecast is a little to the right of the previous one through 24 hours based on the initial position and motion, and is largely an update of the previous forecast after that time. The NHC forecast is close to the latest dynamical model consensus. FORECAST POSITIONS AND MAX WINDS INIT 11/0300Z 25.9N 64.5W 50 KT 60 MPH 12H 11/1200Z 27.7N 64.7W 55 KT 65 MPH 24H 12/0000Z 30.8N 64.1W 55 KT 65 MPH 36H 12/1200Z 33.9N 61.5W 50 KT 60 MPH 48H 13/0000Z 36.6N 56.0W 45 KT 50 MPH 72H 14/0000Z...ABSORBED BY FRONT $$ Forecaster Brennan

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