| NHC Track: https://www.nhc.noaa.gov/refresh/graphics_at5+shtml/?cone#contents Satellite floater: https://www.star.nesdis.noaa.gov/GOES/floater.php?stormid=AL052021 Recon starts July 2nd. Intensity longer term is more uncertain. "After 72 h, the intensity forecast becomes highly uncertain due to possible land interaction and differences in the model forecasts of the upper-level winds. This portion of the NHC intensity forecast maintains a constant 50-kt intensity due to the level of uncertainty." Full NHC Discussion: Potential Tropical Cyclone Five Discussion Number 1 NWS National Hurricane Center Miami FL AL052021 500 PM AST Wed Jun 30 2021 Satellite imagery indicates that the convection associated with the low pressure area over the central tropical Atlantic is becoming better organized. However, earlier scatterometer data showed that the circulation was elongated and not well defined. Since the system is about 48 h away from the Lesser Antilles and is expected to become a tropical storm before reaching the islands, advisories are being initiated at this time on Potential Tropical Cyclone Five. The initial intensity is set to 30 kt based on the scatterometer data and satellite intensity estimates from TAFB and SAB. The initial motion is 285/18. The disturbance is currently on the south side of a strong subtropical ridge, and for the next 72 h the system should move rapidly west-northwestward. Indeed, the forward speed may exceed 25 kt as the system moves through the Lesser Antilles. There is excellent agreement in the guidance on this part of the forecast track. After 72 h, the system is expected to approach a weakness in the ridge caused by a mid-latitude trough over the eastern United States. The should cause the system to slow its forward speed and turn more northwestward. The track guidance become more diverse during this time in regards to how far north the system will turn, and this part of the NHC forecast track is most similar to the GFS and UKMET forecasts. Note that the track forecast is more uncertain than usual since the system does not yet have a well-defined center. The disturbance is currently in a favorable upper-level wind pattern. However, most Atlantic systems in this area moving near 25 kt have trouble strengthening, and there are indications that the fast forward speed may produce some westerly shear. Thus, the NHC intensity forecast for the first 72 h is near the lower edge of the intensity guidance. After 72 h, the intensity forecast becomes highly uncertain due to possible land interaction and differences in the model forecasts of the upper-level winds. This portion of the NHC intensity forecast maintains a constant 50-kt intensity due to the level of uncertainty. Key Messages: 1. The system is expected to become a tropical storm before reaching the Lesser Antilles and tropical storm conditions are possible beginning Friday in portions of the Windward and southern Leeward Islands. 2. Heavy rainfall will move quickly across the Windward and southern Leeward Islands, including Barbados, on Friday. Isolated flash flooding and mudslides are possible. 3. There is a risk of wind and rainfall impacts in portions of the Virgin Islands, Puerto Rico, Hispaniola, Cuba, the Turks and Caicos and the southeastern Bahamas through early next week, although the forecast is more uncertain than usual since the system does not have a well-defined center. Interests in these areas should monitor the system's progress and updates to the forecast. 4. Interests in Florida should monitor updates to the forecast for this system, but it is too soon to determine what if any impacts could occur there next week given the uncertainty in the long-range forecast. FORECAST POSITIONS AND MAX WINDS INIT 30/2100Z 9.6N 43.7W 30 KT 35 MPH...POTENTIAL TROP CYCLONE 12H 01/0600Z 10.2N 46.6W 35 KT 40 MPH...TROPICAL CYCLONE 24H 01/1800Z 11.1N 51.0W 40 KT 45 MPH 36H 02/0600Z 12.4N 56.0W 45 KT 50 MPH 48H 02/1800Z 13.8N 61.2W 45 KT 50 MPH 60H 03/0600Z 15.4N 66.3W 50 KT 60 MPH 72H 03/1800Z 17.0N 70.9W 50 KT 60 MPH 96H 04/1800Z 20.0N 77.0W 50 KT 60 MPH...INLAND 120H 05/1800Z 22.5N 81.5W 50 KT 60 MPH...INLAND $$ Forecaster Beven Potential Tropical Cyclone Five Advisory Number 1 NWS National Hurricane Center Miami FL AL052021 500 PM AST Wed Jun 30 2021 ...TROPICAL DISTURBANCE IN THE ATLANTIC BECOMING BETTER ORGANIZED... ...TROPICAL STORM WATCHES ISSUED FOR PORTIONS OF THE LESSER ANTILLES... SUMMARY OF 500 PM AST...2100 UTC...INFORMATION ---------------------------------------------- LOCATION...9.6N 43.7W ABOUT 1195 MI...1920 KM E OF THE WINDWARD ISLANDS MAXIMUM SUSTAINED WINDS...35 MPH...55 KM/H PRESENT MOVEMENT...WNW OR 285 DEGREES AT 21 MPH...33 KM/H MINIMUM CENTRAL PRESSURE...1008 MB...29.77 INCHES WATCHES AND WARNINGS -------------------- CHANGES WITH THIS ADVISORY: The Meteorological Service of Barbados has issued a Tropical Storm Watch for Barbados, St. Vincent, and the Grenadines. The Meteorological Service of St. Lucia has issued a Tropical Storm Watch for St. Lucia. The Government of France has issued a Tropical Storm Watch for Martinique. SUMMARY OF WATCHES AND WARNINGS IN EFFECT: A Tropical Storm Watch is in effect for... * St. Vincent and the Grenadines * St. Lucia * Barbados * Martinique A Tropical Storm Watch means that tropical storm conditions are possible within the watch area, generally within 48 hours. Interests elsewhere in the Windward Islands, Leeward Islands, the Virgin Islands, Puerto Rico, the Dominican Republic, and Haiti should monitor the progress of this system. Warnings and additional watches will likely be required tonight and on Thursday. For storm information specific to your area, please monitor products issued by your national meteorological service. DISCUSSION AND OUTLOOK ---------------------- At 500 PM AST (2100 UTC), the disturbance was centered near latitude 9.6 North, longitude 43.7 West. The system is moving toward the west-northwest near 21 mph (33 km/h) and this motion is expected to continue with an increase in forward speed during the next couple of days. On the forecast track, the system will pass near or over portions of the Windward Islands or the southern Leeward Islands on Friday, move into the eastern Caribbean Sea late Friday and Friday night, and move near the southern coast of Hispaniola on Saturday. Maximum sustained winds are near 35 mph (55 km/h) with higher gusts. Some strengthening is forecast during the next 48 hours and the disturbance is expected to become a tropical storm tonight or on Thursday. * Formation chance through 48 hours...high...70 percent. * Formation chance through 5 days...high...90 percent. The estimated minimum central pressure is 1008 mb (29.77 inches). HAZARDS AFFECTING LAND ---------------------- Key messages for Potential Tropical Cyclone Five can be found in the Tropical Cyclone Discussion under AWIPS header MIATCDAT5, WMO header WTNT45 KNHC and on the web at www.hurricanes.gov/graphics_at5.shtml?key_messages. WIND: Tropical-storm conditions are possible in portions of the Windward and southern Leeward Islands on Friday. RAINFALL: The potential tropical cyclone will produce rainfall totals of 3 to 6 inches with maximum totals of 8 inches on Friday across the Windward and southern Leeward Islands, including Barbados. This rain may produce isolated flash flooding and mudslides. NEXT ADVISORY ------------- Next intermediate advisory at 800 PM AST. Next complete advisory at 1100 PM AST. $$ Forecaster Beven WTNT65 KNHC 302104 TCUAT5 Potential Tropical Cyclone Five Tropical Cyclone Update NWS National Hurricane Center Miami FL AL052021 500 PM AST Wed Jun 30 2021 The government of France has issued a Tropical Storm Watch for Guadeloupe. NOUS42 KNHC 301605 REPRPD WEATHER RECONNAISSANCE FLIGHTS CARCAH, NATIONAL HURRICANE CENTER, MIAMI, FL. 1205 PM EDT WED 30 JUNE 2021 SUBJECT: TROPICAL CYCLONE PLAN OF THE DAY (TCPOD) VALID 01/1100Z TO 02/1100Z JULY 2021 TCPOD NUMBER.....21-030 I. ATLANTIC REQUIREMENTS 1. SUSPECT AREA (EAST OF WINDWARD ISLANDS) FLIGHT ONE - TEAL 71 A. 02/1200Z B. AFXXX 01BBA INVEST C. 02/0715Z D. 12.7N 58.9W E. 02/1130Z TO 02/1500Z F. SFC TO 10,000 FEET 2. OUTLOOK FOR SUCCEEDING DAY: A. POSSIBLE NOAA P-3 TAIL DOPPLER RADAR MISSION NEAR 13.5N 61.5W FOR 02/1800Z, DEPARTING TNCA AT 02/1400Z. B. POSSIBLE NOAA G-IV SYNOPTIC SURVEILLANCE MISSION AROUND THE SUSPECT AREA FOR THE 03/0000Z SYNOPTIC TIME, DEPARTING KLAL AT 02/1730Z. C. BEGIN 12 HOURLY FIXES AT 02/2330Z IF SYSTEM DEVELOPS. II. PACIFIC REQUIREMENTS 1. NEGATIVE RECONNAISSANCE REQUIREMENTS. 2. OUTLOOK FOR SUCCEEDING DAY.....NEGATIVE. From: https://www.nhc.noaa.gov/recon.php GFS: https://www.tropicaltidbits.com/analysis/models/?model=gfs®ion=atl&pkg=mslp_uv850 Euro: https://www.tropicaltidbits.com/analysis/models/?model=ecmwf®ion=atl&pkg=mslp_uv850 As of posting, GFS still has it stronger longer term than the Euro. We'll have to see how that changes. GFS ensemble members: https://www.tropicaltidbits.com/analysis/models/?model=gfs-ens®ion=atl&pkg=lowlocs It's still a little far out too have an idea how it might impact the Contiguous U.S. Storm specific models and satellite imagery: http://hurricanecity.com/models/models.cgi?basin=al&year=2021&storm=05 For now, focus is on some of the islands where the current forecast is for heavy rain. "This rain may produce isolated flash flooding and mudslides." |