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Post-Tropical Cyclone Leslie Forecast Discussion Number 9

2018-09-25 16:40:18| National Hurricane Center (Atlantic)

Issued at 1100 AM AST Tue Sep 25 2018 676 WTNT43 KNHC 251439 TCDAT3 Post-Tropical Cyclone Leslie Discussion Number 9 NWS National Hurricane Center Miami FL AL132018 1100 AM AST Tue Sep 25 2018 Leslie has become a post-tropical cyclone. Conventional and microwave satellite imagery show that Leslie's surface circulation has become elongated along an intruding baroclinic zone indicated by a recent 1158 UTC ASCAT-A pass. Any deep convection appears to be developing due to dynamic forcing. A rather large stratocumulus cloud shield and associated cooler, stable air is quickly advecting into the area as well. The initial intensity is maintained at 30 kt for this last advisory. Leslie is forecast to strengthen during the next couple of days due to baroclinic processes. The official forecast, based on the GFS and European global models, and the SHIPS statistical intensity guidance, shows an increase of the sustained winds to hurricane force in 2 days, around the same period that the shear drops below 10 kt. The non-tropical low is then forecast to move south of the strong upper-level westerlies and detach from the frontal boundary. According to the global models and the Florida State Cyclone Phase forecast, Leslie should make a transition from a frontal system to an asymmetric shallow warm-core seclusion. Beyond day 3, guidance suggests that Leslie will acquire subtropical characteristics and a more symmetric, deepening warm-core low while meandering in weaker steering currents. The intensity forecast follows this scenario and is based on the aforementioned global and statistical models. Leslie is now moving eastward at a slightly faster forward motion, about 10 kt. A turn to the north is expected in 36 hours followed by a slower westward motion as Leslie slips south of the mid-latitude westerlies. Through the remaining portion of the forecast, Leslie should move at a slower speed generally westward as a ridge builds to the north. NHC forecast is nudged toward the TVCN consensus through 48 hours, then follows more closely to the GFEX (GFS/ECMWF) consensus model. This is the last advisory issued by the National Hurricane Center on Leslie. Additional information on this system can be found in High Seas Forecasts issued by the National Weather Service, under AWIPS header NFDHSFAT1, WMO header FZNT01 KWBC, and available on the Web at https://ocean.weather.gov/shtml/NFDHSFAT1.shtml. FORECAST POSITIONS AND MAX WINDS INIT 25/1500Z 31.6N 44.4W 30 KT 35 MPH...POST-TROPICAL 12H 26/0000Z 32.1N 42.5W 40 KT 45 MPH...POST-TROP/EXTRATROP 24H 26/1200Z 33.6N 40.1W 50 KT 60 MPH...POST-TROP/EXTRATROP 36H 27/0000Z 35.6N 39.9W 60 KT 70 MPH...POST-TROP/EXTRATROP 48H 27/1200Z 36.1N 41.7W 65 KT 75 MPH...POST-TROP/EXTRATROP 72H 28/1200Z 35.5N 45.3W 60 KT 70 MPH...SUBTROPICAL STORM 96H 29/1200Z 34.6N 48.1W 55 KT 65 MPH...SUBTROPICAL STORM 120H 30/1200Z 34.4N 49.6W 50 KT 60 MPH...SUBTROPICAL STORM $$ Forecaster Roberts

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Post-Tropical Cyclone Leslie Forecast Advisory Number 9

2018-09-25 16:38:17| National Hurricane Center (Atlantic)

Issued at 1500 UTC TUE SEP 25 2018 558 WTNT23 KNHC 251438 TCMAT3 POST-TROPICAL CYCLONE LESLIE FORECAST/ADVISORY NUMBER 9 NWS NATIONAL HURRICANE CENTER MIAMI FL AL132018 1500 UTC TUE SEP 25 2018 THERE ARE NO COASTAL WATCHES OR WARNINGS IN EFFECT. POST-TROPICAL CYCLONE CENTER LOCATED NEAR 31.6N 44.4W AT 25/1500Z POSITION ACCURATE WITHIN 30 NM PRESENT MOVEMENT TOWARD THE EAST OR 100 DEGREES AT 10 KT ESTIMATED MINIMUM CENTRAL PRESSURE 1007 MB MAX SUSTAINED WINDS 30 KT WITH GUSTS TO 40 KT. 12 FT SEAS..270NE 150SE 150SW 0NW. WINDS AND SEAS VARY GREATLY IN EACH QUADRANT. RADII IN NAUTICAL MILES ARE THE LARGEST RADII EXPECTED ANYWHERE IN THAT QUADRANT. REPEAT...CENTER LOCATED NEAR 31.6N 44.4W AT 25/1500Z AT 25/1200Z CENTER WAS LOCATED NEAR 31.7N 45.2W FORECAST VALID 26/0000Z 32.1N 42.5W...POST-TROP/EXTRATROP MAX WIND 40 KT...GUSTS 50 KT. 34 KT... 0NE 0SE 0SW 240NW. FORECAST VALID 26/1200Z 33.6N 40.1W...POST-TROP/EXTRATROP MAX WIND 50 KT...GUSTS 60 KT. 50 KT... 0NE 0SE 0SW 120NW. 34 KT... 0NE 150SE 210SW 300NW. FORECAST VALID 27/0000Z 35.6N 39.9W...POST-TROP/EXTRATROP MAX WIND 60 KT...GUSTS 75 KT. 50 KT... 0NE 0SE 50SW 130NW. 34 KT...270NE 200SE 280SW 350NW. FORECAST VALID 27/1200Z 36.1N 41.7W...POST-TROP/EXTRATROP MAX WIND 65 KT...GUSTS 80 KT. 50 KT...150NE 100SE 180SW 240NW. 34 KT...290NE 210SE 300SW 420NW. FORECAST VALID 28/1200Z 35.5N 45.3W...SUBTROPICAL STORM MAX WIND 60 KT...GUSTS 75 KT. 50 KT...120NE 90SE 90SW 150NW. 34 KT...200NE 150SE 250SW 350NW. EXTENDED OUTLOOK. NOTE...ERRORS FOR TRACK HAVE AVERAGED NEAR 150 NM ON DAY 4 AND 175 NM ON DAY 5...AND FOR INTENSITY NEAR 15 KT EACH DAY OUTLOOK VALID 29/1200Z 34.6N 48.1W...SUBTROPICAL STORM MAX WIND 55 KT...GUSTS 65 KT. OUTLOOK VALID 30/1200Z 34.4N 49.6W...SUBTROPICAL STORM MAX WIND 50 KT...GUSTS 60 KT. REQUEST FOR 3 HOURLY SHIP REPORTS WITHIN 300 MILES OF 31.6N 44.4W THIS IS THE LAST FORECAST/ADVISORY ISSUED BY THE NATIONAL HURRICANE CENTER ON THIS SYSTEM. ADDITIONAL INFORMATION ON THIS SYSTEM CAN BE FOUND IN HIGH SEAS FORECASTS ISSUED BY THE NATIONAL WEATHER SERVICE...UNDER AWIPS HEADER NFDHSFAT1 AND WMO HEADER FZNT01 KWBC. $$ FORECASTER ROBERTS

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Post-Tropical Cyclone Leslie Wind Speed Probabilities Number 9

2018-09-25 16:38:17| National Hurricane Center (Atlantic)

Issued at 1500 UTC TUE SEP 25 2018 474 FONT13 KNHC 251438 PWSAT3 POST-TROPICAL CYCLONE LESLIE WIND SPEED PROBABILITIES NUMBER 9 NWS NATIONAL HURRICANE CENTER MIAMI FL AL132018 1500 UTC TUE SEP 25 2018 AT 1500Z THE CENTER OF POST-TROPICAL CYCLONE LESLIE WAS LOCATED NEAR LATITUDE 31.6 NORTH...LONGITUDE 44.4 WEST WITH MAXIMUM SUSTAINED WINDS NEAR 30 KTS...35 MPH...55 KM/H. Z INDICATES COORDINATED UNIVERSAL TIME (GREENWICH) ATLANTIC STANDARD TIME (AST)...SUBTRACT 4 HOURS FROM Z TIME EASTERN DAYLIGHT TIME (EDT)...SUBTRACT 4 HOURS FROM Z TIME CENTRAL DAYLIGHT TIME (CDT)...SUBTRACT 5 HOURS FROM Z TIME WIND SPEED PROBABILITY TABLE FOR SPECIFIC LOCATIONS CHANCES OF SUSTAINED (1-MINUTE AVERAGE) WIND SPEEDS OF AT LEAST ...34 KT (39 MPH... 63 KM/H)... ...50 KT (58 MPH... 93 KM/H)... ...64 KT (74 MPH...119 KM/H)... FOR LOCATIONS AND TIME PERIODS DURING THE NEXT 5 DAYS PROBABILITIES FOR LOCATIONS ARE GIVEN AS OP(CP) WHERE OP IS THE PROBABILITY OF THE EVENT BEGINNING DURING AN INDIVIDUAL TIME PERIOD (ONSET PROBABILITY) (CP) IS THE PROBABILITY OF THE EVENT OCCURRING BETWEEN 12Z TUE AND THE FORECAST HOUR (CUMULATIVE PROBABILITY) PROBABILITIES ARE GIVEN IN PERCENT X INDICATES PROBABILITIES LESS THAN 1 PERCENT PROBABILITIES FOR 34 KT AND 50 KT ARE SHOWN AT A GIVEN LOCATION WHEN THE 5-DAY CUMULATIVE PROBABILITY IS AT LEAST 3 PERCENT. PROBABILITIES FOR 34...50...64 KT SHOWN WHEN THE 5-DAY 64-KT CUMULATIVE PROBABILITY IS AT LEAST 1 PERCENT. - - - - WIND SPEED PROBABILITIES FOR SELECTED LOCATIONS - - - - FROM FROM FROM FROM FROM FROM FROM TIME 12Z TUE 00Z WED 12Z WED 00Z THU 12Z THU 12Z FRI 12Z SAT PERIODS TO TO TO TO TO TO TO 00Z WED 12Z WED 00Z THU 12Z THU 12Z FRI 12Z SAT 12Z SUN FORECAST HOUR (12) (24) (36) (48) (72) (96) (120) - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - LOCATION KT $$ FORECASTER ROBERTS

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Post-Tropical Cyclone Joyce Graphics

2018-09-19 04:36:34| National Hurricane Center (Atlantic)

5-Day Uncertainty Track last updated Wed, 19 Sep 2018 02:36:34 GMT Wind Speed Probabilities last updated Wed, 19 Sep 2018 03:21:29 GMT

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Post-Tropical Cyclone Joyce Forecast Discussion Number 26

2018-09-19 04:35:29| National Hurricane Center (Atlantic)

Issued at 1100 PM AST Tue Sep 18 2018 630 WTNT45 KNHC 190235 TCDAT5 Post-Tropical Cyclone Joyce Discussion Number 26 NWS National Hurricane Center Miami FL AL102018 1100 PM AST Tue Sep 18 2018 During the past couple of days, Joyce had been producing patches of deep convection that would quickly shear off due to strong westerly winds aloft. Each convective burst appeared weaker than the previous one, and during the past 12-18 hours, the circulation has been nearly devoid of deep convection. Therefore, Joyce no longer meets the criteria of a tropical cyclone, and this is the last advisory issued by the National Hurricane Center on this system. The initial wind speed is held at 25 kt, in agreement with a recent ASCAT pass around 2200Z that showed maximum winds in the 20-25 kt range. The remnant low is expected to gradually weaken and ultimately dissipate in a couple of days due to dry and stable air, cool SSTs, and moderate to strong westerly shear. Joyce is moving south-southwestward at 7 kt on the east side of a low- to mid-level ridge. A turn to the southwest is expected on Wednesday as the ridge builds to the northeast of the cyclone, and that motion should continue until the remnant low dissipates. The NHC track forecast lies near the middle of the guidance envelope. FORECAST POSITIONS AND MAX WINDS INIT 19/0300Z 30.4N 27.9W 25 KT 30 MPH...POST-TROP/REMNT LOW 12H 19/1200Z 29.9N 28.7W 20 KT 25 MPH...POST-TROP/REMNT LOW 24H 20/0000Z 29.4N 29.9W 20 KT 25 MPH...POST-TROP/REMNT LOW 36H 20/1200Z 28.9N 31.5W 15 KT 15 MPH...POST-TROP/REMNT LOW 48H 21/0000Z...DISSIPATED $$ Forecaster Cangialosi

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