| Was 99L. Track: http://www.nhc.noaa.gov/refresh/graphics_at1+shtml/053407.shtml?5day?large#contents TROPICAL DEPRESSION SIX SPECIAL DISCUSSION NUMBER 1 NWS NATIONAL HURRICANE CENTER MIAMI FL AL062015 130 AM AST SUN AUG 30 2015 The well-defined low pressure system located to the west of Conakry, Guinea, has acquired sufficient organized convection to be classified as a tropical depression. The initial intensity of 30 kt is based on a Dvorak satellite intensity estimate of T2.0/30 kt from TAFB and two earlier ASCAT scatterometer passes indicating at least 30 kt in the southern semicircle. The initial motion estimate is 305/10 kt. The depression is located south of a deep-layer subtropical ridge that extends westward across northwestern Africa and into the eastern Atlantic for several hundred miles. However, a weakness is located in a portion of the ridge to the north of the Cape Verde Islands due to a pronounced mid-latitude trough noted in water vapor imagery digging east-southeastward. This should allow the cyclone to move northwestward toward the Cape Verde Islands through 48 hours. After that time, the NHC model guidance is in fair agreement on the aforementioned trough lifting out, allowing the ridge to build back in, which is expected to force the cyclone on a more westward track. The NHC track forecast lies close to the consensus models TVCA and GFEX. The depression is embedded within favorable environmental and oceanic conditions consisting of low vertical wind shear of less than 10 kt, a moist mid-troposphere, and sea-surface temperatures greater than 28 deg C, which should allow for steady strengthening for the next 48 hours or so. The main inhibiting factor is the decreasing instability ahead of the cyclone after 24-36 hours. However, the possibility still exists for the system to reach hurricane status before or while it moves through the Cape Verde Islands in 36-48 hours. For this reason, the Meteorological Service of the Cape Verde Islands has issued a Hurricane Watch and a Tropical Storm Warning for all of the Cape Verdes. The official intensity forecast is basically a blend of the SHIPS and LGEM models. FORECAST POSITIONS AND MAX WINDS INIT 30/0530Z 12.1N 18.4W 30 KT 35 MPH 12H 30/1200Z 12.7N 19.5W 35 KT 40 MPH 24H 31/0000Z 13.9N 21.2W 45 KT 50 MPH 36H 31/1200Z 15.3N 23.1W 55 KT 65 MPH 48H 01/0000Z 16.6N 24.9W 60 KT 70 MPH 72H 02/0000Z 18.3N 29.0W 60 KT 70 MPH 96H 03/0000Z 18.9N 32.9W 55 KT 65 MPH 120H 04/0000Z 19.3N 36.8W 50 KT 60 MPH $$ Forecaster Stewart TROPICAL DEPRESSION SIX SPECIAL ADVISORY NUMBER 1 NWS NATIONAL HURRICANE CENTER MIAMI FL AL062015 130 AM AST SUN AUG 30 2015 ...NEW TROPICAL DEPRESSION FORMS IN THE FAR EASTERN ATLANTIC... ...HURRICANE WATCH AND TROPICAL STORM WARNING ISSUED FOR THE CAPE VERDE ISLANDS... SUMMARY OF 130 AM AST...0530 UTC...INFORMATION ---------------------------------------------- LOCATION...12.1N 18.4W ABOUT 445 MI...715 KM ESE OF THE SOUTHERNMOST CAPE VERDE ISLANDS MAXIMUM SUSTAINED WINDS...35 MPH...55 KM/H PRESENT MOVEMENT...NW OR 305 DEGREES AT 12 MPH...19 KM/H MINIMUM CENTRAL PRESSURE...1007 MB...29.74 INCHES WATCHES AND WARNINGS -------------------- CHANGES WITH THIS ADVISORY: The Meteorological Service of the Cape Verde Islands has issued a Hurricane Watch and a Tropical Storm Warning for all of the Cape Verde Islands. SUMMARY OF WATCHES AND WARNINGS IN EFFECT: A Hurricane Watch is in effect for... * Cape Verde Islands A Tropical Storm Warning is in effect for... * Cape Verde Islands A Hurricane Watch means that hurricane conditions are possible within the watch area. A watch is typically issued 48 hours before the anticipated first occurrence of tropical-storm-force winds, conditions that make outside preparations difficult or dangerous. A Tropical Storm Warning means that tropical storm conditions are expected somewhere within the warning area within 36 hours. For storm information specific to your area, please monitor products issued by your national meteorological service. DISCUSSION AND 48-HOUR OUTLOOK ------------------------------ At 130 AM AST (0530 UTC), the center of Tropical Depression Six was located near latitude 12.1 North, longitude 18.4 West. The depression is moving toward the northwest near 12 mph (19 km/h) and this motion is expected to continue through Tuesday. On the forecast track the depression is expected to move through the Cape Verde Islands as a tropical storm on Monday. Maximum sustained winds are near 35 mph (55 km/h) with higher gusts. Some strengthening is forecast during the next 48 hours, and the depression is expected to become a tropical storm later this morning. The estimated minimum central pressure is 1007 mb (29.74 inches). HAZARDS AFFECTING LAND ---------------------- WIND: Tropical storm conditions are expected to first reach the coast within the warning area by early Monday, making outside preparations difficult or dangerous. Hurricane conditions are also possible within the watch area by late Monday. RAINFALL: The depression is expected to produce total rain accumulations of 3 to 5 inches over the Cape Verde Islands, with possible isolated maximum amounts of 8 inches on Monday. These rains could produce flash flooding and mudslides. NEXT ADVISORY ------------- Next complete advisory at 500 AM AST. $$ Forecaster Stewart http://hurricanes.gov/ |