NHC Hurricane Advisories
Issued at 1100 PM EDT Thu Sep 12 2019
000 WTNT44 KNHC 130257 TCDAT4 Potential Tropical Cyclone Nine Discussion Number 2 NWS National Hurricane Center Miami FL AL092019 1100 PM EDT Thu Sep 12 2019 An Air Force Reserve reconnaissance aircraft earlier this afternoon found a closed but very broad cyclonic circulation along with 1000-ft flight-level and SFMR surface winds that supported an intensity of 25 kt. Recent ship reports also support an intensity of 25 kt, although stronger winds could be present in some of the fragmented convective bands located in the northeastern quadrant. The initial motion is an uncertain 310/02 kt. The disturbance has been meandering over the southeastern Bahamas the past several hours due to southwesterly mid-/upper-level winds associated with an east-west oriented shortwave trough impinging on the west side of the circulation. A large upper-low located over the central Gulf of Mexico that has produced this shortwave trough is expected to spin out another trough on Friday that will move across South Florida and the Straits, impinging on the disturbance and hindering any significant northwestward motion. By late Friday and Saturday, however, the upper-level is expected to have moved into the western Gulf of Mexico, ending any negative effects in the disturbance. This expected to result in the formation of a tropical cyclone with a deeper vortex column that should get steered basically northwestward in combined deep-layer southeasterly flow between the upper-low to the west and a ridge to the northeast. The new NHC track forecast is basically just an extension of the previous forecast track, albeit a little slower, and lies down the middle of the widely divergent guidance envelope, close to the various simple consensus models, and to the right of the NOAA-HCCA consensus model. The aforementioned complex steering flow pattern will also play a major role in the intensification process. The two shortwaves troughs are expected to hinder significant convective organization for the next 24-30 hours due to their localized increase in the vertical shear and intrusions of dry air. By 36 hours and beyond, however, those negative factors are forecast to abate, resulting in the disturbance moving underneath an axis of strong upper-level difluence and speed divergence near or just to the east of the Florida east coast. This more favorable upper-level outflow regime should allow for convection to develop and organize fairly quickly around the center before the system reaches the Florida east coast, which should result in the formation of a moderate tropical storm. Although the center is forecast to be inland at 72-96 hours, the center is expected be close enough to the coast to keep tropical-storm-force ongoing over the coastal waters through 120 hours. The official intensity forecast is identical to the previous advisory and follows a blend of the consensus models HCCA and IVCN. Key Messages: 1. The disturbance is expected to become a tropical storm and bring tropical storm force winds to portions of the northwest Bahamas within 36 hours. Note that forecast uncertainty for these disturbances is generally larger than for tropical cyclones, especially beyond 48-72 hours. 2. The system is expected to bring tropical-storm-force winds and heavy rainfall to portions of the northwest Bahamas on Friday and Saturday. Significant storm surge is not expected in the northwest Bahamas from this system. Residents there should follow any advice given by local officials. 3. The system could bring tropical-storm-force winds and rainfall to portions of the Florida east coast over the weekend. Residents there should monitor the progress of this system. FORECAST POSITIONS AND MAX WINDS INIT 13/0300Z 23.8N 74.5W 25 KT 30 MPH...POTENTIAL TROP CYCLONE 12H 13/1200Z 24.6N 75.6W 30 KT 35 MPH...POTENTIAL TROP CYCLONE 24H 14/0000Z 25.5N 77.2W 30 KT 35 MPH...TROPICAL CYCLONE 36H 14/1200Z 26.5N 78.8W 40 KT 45 MPH 48H 15/0000Z 27.5N 80.2W 45 KT 50 MPH 72H 16/0000Z 29.8N 81.8W 40 KT 45 MPH...INLAND 96H 17/0000Z 30.8N 81.4W 40 KT 45 MPH...INLAND 120H 18/0000Z 31.8N 79.8W 45 KT 50 MPH...OVER WATER $$ Forecaster Stewart
Issued at 0300 UTC FRI SEP 13 2019
000 WTNT24 KNHC 130256 TCMAT4 POTENTIAL TROPICAL CYCLONE NINE FORECAST/ADVISORY NUMBER 2 NWS NATIONAL HURRICANE CENTER MIAMI FL AL092019 0300 UTC FRI SEP 13 2019 CHANGES IN WATCHES AND WARNINGS WITH THIS ADVISORY... A TROPICAL STORM WATCH HAS BEEN ISSUED FOR PORTIONS OF THE COAST OF EAST-CENTRAL FLORIDA FROM JUPITER INLET NORTHWARD TO THE VOLUSIA-BREVARD COUNTY LINE. SUMMARY OF WATCHES AND WARNINGS IN EFFECT... A TROPICAL STORM WARNING IS IN EFFECT FOR... * NORTHWESTERN BAHAMAS EXCLUDING ANDROS ISLAND A TROPICAL STORM WATCH IS IN EFFECT FOR... * JUPITER INLET TO VOLUSIA-BREVARD COUNTY LINE A TROPICAL STORM WARNING MEANS THAT TROPICAL STORM CONDITIONS ARE EXPECTED SOMEWHERE WITHIN THE WARNING AREA WITHIN 36 HOURS. A TROPICAL STORM WATCH MEANS THAT TROPICAL STORM CONDITIONS ARE POSSIBLE WITHIN THE WATCH AREA...GENERALLY WITHIN 48 HOURS. INTERESTS ELSEWHERE ALONG THE EAST COAST OF FLORIDA SHOULD MONITOR THE PROGRESS OF THIS SYSTEM. POTENTIAL TROP CYCLONE CENTER LOCATED NEAR 23.8N 74.5W AT 13/0300Z POSITION ACCURATE WITHIN 45 NM PRESENT MOVEMENT TOWARD THE NORTHWEST OR 310 DEGREES AT 2 KT ESTIMATED MINIMUM CENTRAL PRESSURE 1009 MB MAX SUSTAINED WINDS 25 KT WITH GUSTS TO 35 KT. 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 23.8N 74.5W AT 13/0300Z AT 13/0000Z CENTER WAS LOCATED NEAR 23.7N 74.4W FORECAST VALID 13/1200Z 24.6N 75.6W MAX WIND 30 KT...GUSTS 40 KT. FORECAST VALID 14/0000Z 25.5N 77.2W...TROPICAL CYCLONE MAX WIND 30 KT...GUSTS 40 KT. FORECAST VALID 14/1200Z 26.5N 78.8W MAX WIND 40 KT...GUSTS 50 KT. 34 KT... 60NE 40SE 0SW 50NW. FORECAST VALID 15/0000Z 27.5N 80.2W MAX WIND 45 KT...GUSTS 55 KT. 34 KT... 70NE 60SE 30SW 70NW. FORECAST VALID 16/0000Z 29.8N 81.8W...INLAND MAX WIND 40 KT...GUSTS 50 KT. 34 KT... 90NE 70SE 30SW 40NW. 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 17/0000Z 30.8N 81.4W...INLAND MAX WIND 40 KT...GUSTS 50 KT. OUTLOOK VALID 18/0000Z 31.8N 79.8W...OVER WATER MAX WIND 45 KT...GUSTS 55 KT. REQUEST FOR 3 HOURLY SHIP REPORTS WITHIN 300 MILES OF 23.8N 74.5W INTERMEDIATE PUBLIC ADVISORY...WTNT34 KNHC/MIATCPAT4...AT 13/0600Z NEXT ADVISORY AT 13/0900Z $$ FORECASTER STEWART
Issued at 1100 PM EDT Thu Sep 12 2019
000 WTNT34 KNHC 130256 TCPAT4 BULLETIN Potential Tropical Cyclone Nine Advisory Number 2 NWS National Hurricane Center Miami FL AL092019 1100 PM EDT Thu Sep 12 2019 ...TROPICAL DISTURBANCE MEANDERING OVER THE SOUTHEASTERN BAHAMAS... ...TROPICAL STORM WATCH ISSUED FOR PORTIONS OF THE FLORIDA EAST COAST... SUMMARY OF 1100 PM EDT...0300 UTC...INFORMATION ----------------------------------------------- LOCATION...23.8N 74.5W ABOUT 320 MI...520 KM SE OF FREEPORT GRAND BAHAMA ISLAND ABOUT 240 MI...390 KM SE OF GREAT ABACO ISLAND MAXIMUM SUSTAINED WINDS...30 MPH...45 KM/H PRESENT MOVEMENT...NW OR 310 DEGREES AT 2 MPH...4 KM/H MINIMUM CENTRAL PRESSURE...1009 MB...29.80 INCHES WATCHES AND WARNINGS -------------------- CHANGES WITH THIS ADVISORY: A Tropical Storm Watch has been issued for portions of the coast of east-central Florida from Jupiter Inlet northward to the Volusia-Brevard County line. SUMMARY OF WATCHES AND WARNINGS IN EFFECT: A Tropical Storm Warning is in effect for... * Northwestern Bahamas excluding Andros Island A Tropical Storm Watch is in effect for... * Jupiter Inlet to Volusia-Brevard County line A Tropical Storm Warning means that tropical storm conditions are expected somewhere within the warning area within 36 hours. A Tropical Storm Watch means that tropical storm conditions are possible within the watch area, generally within 48 hours. Interests elsewhere along the east coast of Florida should monitor the progress of this system. For storm information specific to your area, please monitor products issued by your national meteorological service. DISCUSSION AND OUTLOOK ---------------------- At 1100 PM EDT (0300 UTC), the poorly defined center of the disturbance was located by satellite and surface observations near the disturbance was centered near latitude 23.8 North, longitude 74.5 West. The disturbance has been meandering over the southeastern Bahamas. However, the system is expected to move slowly northwestward on Friday, and continue that motion through the weekend. On the forecast track, the system is anticipated to move across the central and northwestern Bahamas on Friday, and along or over the east coast of Florida on Saturday. Maximum sustained winds are near 30 mph (45 km/h) with higher gusts. The disturbance is forecast to become a tropical depression or a tropical storm during the next day or so. Environmental conditions are favorable for a tropical depression or tropical storm to form within the next day or two. * Formation chance through 48 hours...high...80 percent * Formation chance through 5 days...high...90 percent The estimated minimum central pressure is 1009 mb (29.80 inches). HAZARDS AFFECTING LAND ---------------------- WIND: Tropical storm conditions are expected within the warning area in the northwest Bahamas by late Friday. Tropical storm conditions are possible in the watch area on the Florida peninsula by Saturday. RAINFALL: The potential tropical cyclone is expected to produce total rainfall accumulations through Sunday: The Bahamas...3 to 5 inches, isolated maximum amounts around 7 inches. The U.S. Southeast Coast from central Florida through southeastern Georgia...2 to 4 inches. STORM SURGE: This system is not expected to product significant storm surge in the northwest Bahamas. NEXT ADVISORY ------------- Next intermediate advisory at 200 AM EDT. Next complete advisory at 500 AM EDT. $$ Forecaster Stewart
…TROPICAL DISTURBANCE MEANDERING OVER THE SOUTHEASTERN BAHAMAS… …TROPICAL STORM WATCH ISSUED FOR PORTIONS OF THE FLORIDA EAST COAST…
As of 11:00 PM EDT Thu Sep 12
the center of Nine was located near 23.8, -74.5
with movement NW at 2 mph.
The minimum central pressure was 1009 mb
with maximum sustained winds of about 30 mph.