National Hurricane Center (Atlantic)
ABNT20 KNHC 221111
Tropical Weather Outlook
NWS National Hurricane Center Miami FL
800 AM EDT Sat Sep 22 2018
For the North Atlantic...Caribbean Sea and the Gulf of Mexico:
The National Hurricane Center is issuing advisories on Tropical
Depression Eleven, located about 500 miles east of the Windward
Shower and thunderstorm activity continues to become better
organized near the center of a low pressure system located about
500 miles south of the southern Cabo Verde Islands, and a tropical
depression appears to be forming. If these trends continue,
advisories will be initiated on this system later today while the
low moves westward at about 20 mph.
* Formation chance through 48 hours...high...80 percent.
* Formation chance through 5 days...high...80 percent.
A broad area of low pressure located about 200 miles south of
Bermuda is producing only minimal shower activity. Strong upper-
level winds are expected to diminish by Sunday or Monday, which
could allow for some slow development of this system while it moves
westward and then northwestward over the southwestern Atlantic
Ocean. By the middle of next week, upper-level winds are likely to
strengthen again, which would limit additional development as the
system moves closer to the southeastern coast of the United States.
* Formation chance through 48 hours...low...10 percent.
* Formation chance through 5 days...low...30 percent.
Satellite imagery indicates that a non-tropical low pressure system
is forming along a frontal boundary about 900 miles west-southwest
of the Azores. Conditions are expected to become conducive for the
low to acquire subtropical or tropical characteristics, and a
subtropical or tropical cyclone is likely to form by early next week
while the low meanders over the central Atlantic Ocean. For more
information on this system, see High Seas Forecasts issued by the
National Weather Service.
* Formation chance through 48 hours...medium...60 percent.
* Formation chance through 5 days...high...70 percent.
Public Advisories on Tropical Depression Eleven are issued under WMO
header WTNT31 KNHC and under AWIPS header MIATCPAT1.
Forecast/Advisories on Tropical Depression Eleven are issued under
WMO header WTNT21 KNHC and under AWIPS header MIATCMAT1.
High Seas Forecasts issued by the National Weather Service can be
found under AWIPS header NFDHSFAT1, WMO header FZNT01 KWBC, and
on the Web at https://ocean.weather.gov/shtml/NFDHSFAT1.shtml.
Issued at 500 AM AST Sat Sep 22 2018
624 WTNT41 KNHC 220836 TCDAT1 Tropical Depression Eleven Discussion Number 2 NWS National Hurricane Center Miami FL AL112018 500 AM AST Sat Sep 22 2018 Deep convection remains displaced to the east of the depression's center due to 30-40 kt of westerly shear. Although Dvorak final-T numbers from TAFB and SAB have decreased since yesterday--now a consensus T1.0--the initial intensity is held, perhaps generously, at 30 kt. Strong westerly shear is expected to persist for several days, which at the very least will prevent the depression from getting any better organized. Since the global models show the depression opening up into a trough in about 24 hours, the new NHC intensity forecast brings down the winds a little faster, shows the system becoming a remnant low by 36 hours, and dissipates the low entirely by 48 hours well east of the Windward Islands. This evolution could certainly occur more quickly than indicated by the official forecast. The center of the depression has not been moving much, and it's possible the sheared convection is trying to pull it back toward the east. However, the average motion over the past 12 hours is westward, or 270/4 kt. The track guidance insists that the depression should move slowly west-northwestward over the next couple of days, but given that the system has not made any northward progress, I elected to skirt the southern edge of the guidance envelope. This new forecast is a little south of the previous NHC track prediction. FORECAST POSITIONS AND MAX WINDS INIT 22/0900Z 13.0N 53.5W 30 KT 35 MPH 12H 22/1800Z 13.3N 54.3W 30 KT 35 MPH 24H 23/0600Z 13.6N 55.4W 25 KT 30 MPH 36H 23/1800Z 13.8N 56.8W 25 KT 30 MPH...POST-TROP/REMNT LOW 48H 24/0600Z...DISSIPATED $$ Forecaster Berg
...TROPICAL DEPRESSION NOT MOVING VERY MUCH... ...EXPECTED TO DISSIPATE IN A DAY OR TWO... As of 5:00 AM AST Sat Sep 22 the center of Eleven was located near 13.0, -53.5 with movement W at 5 mph. The minimum central pressure was 1007 mb with maximum sustained winds of about 35 mph.
Issued at 500 AM AST Sat Sep 22 2018
495 WTNT31 KNHC 220835 TCPAT1 BULLETIN Tropical Depression Eleven Advisory Number 2 NWS National Hurricane Center Miami FL AL112018 500 AM AST Sat Sep 22 2018 ...TROPICAL DEPRESSION NOT MOVING VERY MUCH... ...EXPECTED TO DISSIPATE IN A DAY OR TWO... SUMMARY OF 500 AM AST...0900 UTC...INFORMATION ---------------------------------------------- LOCATION...13.0N 53.5W ABOUT 505 MI...810 KM E OF THE WINDWARD ISLANDS MAXIMUM SUSTAINED WINDS...35 MPH...55 KM/H PRESENT MOVEMENT...W OR 270 DEGREES AT 5 MPH...7 KM/H MINIMUM CENTRAL PRESSURE...1007 MB...29.74 INCHES WATCHES AND WARNINGS -------------------- There are no coastal watches or warnings in effect. DISCUSSION AND OUTLOOK ---------------------- At 500 AM AST (0900 UTC), the center of Tropical Depression Eleven was located near latitude 13.0 North, longitude 53.5 West. The depression is moving slowly toward the west near 5 mph (7 km/h). A slow westward or west-northwestward motion is expected during the next couple of days. Maximum sustained winds are near 35 mph (55 km/h) with higher gusts. Little change in strength is forecast during the next day or so, and the depression is expected to dissipate east of the Lesser Antilles by Sunday night. The estimated minimum central pressure is 1007 mb (29.74 inches). HAZARDS AFFECTING LAND ---------------------- None NEXT ADVISORY ------------- Next complete advisory at 1100 AM AST. $$ Forecaster Berg
Issued at 0900 UTC SAT SEP 22 2018
494 WTNT21 KNHC 220835 TCMAT1 TROPICAL DEPRESSION ELEVEN FORECAST/ADVISORY NUMBER 2 NWS NATIONAL HURRICANE CENTER MIAMI FL AL112018 0900 UTC SAT SEP 22 2018 THERE ARE NO COASTAL WATCHES OR WARNINGS IN EFFECT. TROPICAL DEPRESSION CENTER LOCATED NEAR 13.0N 53.5W AT 22/0900Z POSITION ACCURATE WITHIN 15 NM PRESENT MOVEMENT TOWARD THE WEST OR 270 DEGREES AT 4 KT ESTIMATED MINIMUM CENTRAL PRESSURE 1007 MB MAX SUSTAINED WINDS 30 KT WITH GUSTS TO 40 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 13.0N 53.5W AT 22/0900Z AT 22/0600Z CENTER WAS LOCATED NEAR 13.0N 53.5W FORECAST VALID 22/1800Z 13.3N 54.3W MAX WIND 30 KT...GUSTS 40 KT. FORECAST VALID 23/0600Z 13.6N 55.4W MAX WIND 25 KT...GUSTS 35 KT. FORECAST VALID 23/1800Z 13.8N 56.8W...POST-TROP/REMNT LOW MAX WIND 25 KT...GUSTS 35 KT. FORECAST VALID 24/0600Z...DISSIPATED REQUEST FOR 3 HOURLY SHIP REPORTS WITHIN 300 MILES OF 13.0N 53.5W NEXT ADVISORY AT 22/1500Z $$ FORECASTER BERG
Issued at 0900 UTC SAT SEP 22 2018
441 FONT11 KNHC 220835 PWSAT1 TROPICAL DEPRESSION ELEVEN WIND SPEED PROBABILITIES NUMBER 2 NWS NATIONAL HURRICANE CENTER MIAMI FL AL112018 0900 UTC SAT SEP 22 2018 AT 0900Z THE CENTER OF TROPICAL DEPRESSION ELEVEN WAS LOCATED NEAR LATITUDE 13.0 NORTH...LONGITUDE 53.5 WEST WITH MAXIMUM SUSTAINED WINDS NEAR 30 KTS...35 MPH...55 KM/H. Z INDICATES COORDINATED UNIVERSAL TIME (GREENWICH) ATLANTIC STANDARD TIME (AST)...SUBTRACT 4 HOURS FROM Z TIME EASTERN DAYLIGHT TIME (EDT)...SUBTRACT 4 HOURS FROM Z TIME CENTRAL DAYLIGHT TIME (CDT)...SUBTRACT 5 HOURS FROM Z TIME WIND SPEED PROBABILITY TABLE FOR SPECIFIC LOCATIONS CHANCES OF SUSTAINED (1-MINUTE AVERAGE) WIND SPEEDS OF AT LEAST ...34 KT (39 MPH... 63 KM/H)... ...50 KT (58 MPH... 93 KM/H)... ...64 KT (74 MPH...119 KM/H)... FOR LOCATIONS AND TIME PERIODS DURING THE NEXT 5 DAYS PROBABILITIES FOR LOCATIONS ARE GIVEN AS OP(CP) WHERE OP IS THE PROBABILITY OF THE EVENT BEGINNING DURING AN INDIVIDUAL TIME PERIOD (ONSET PROBABILITY) (CP) IS THE PROBABILITY OF THE EVENT OCCURRING BETWEEN 06Z SAT AND THE FORECAST HOUR (CUMULATIVE PROBABILITY) PROBABILITIES ARE GIVEN IN PERCENT X INDICATES PROBABILITIES LESS THAN 1 PERCENT PROBABILITIES FOR 34 KT AND 50 KT ARE SHOWN AT A GIVEN LOCATION WHEN THE 5-DAY CUMULATIVE PROBABILITY IS AT LEAST 3 PERCENT. PROBABILITIES FOR 34...50...64 KT SHOWN WHEN THE 5-DAY 64-KT CUMULATIVE PROBABILITY IS AT LEAST 1 PERCENT. - - - - WIND SPEED PROBABILITIES FOR SELECTED LOCATIONS - - - - FROM FROM FROM FROM FROM FROM FROM TIME 06Z SAT 18Z SAT 06Z SUN 18Z SUN 06Z MON 06Z TUE 06Z WED PERIODS TO TO TO TO TO TO TO 18Z SAT 06Z SUN 18Z SUN 06Z MON 06Z TUE 06Z WED 06Z THU FORECAST HOUR (12) (24) (36) (48) (72) (96) (120) - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - LOCATION KT $$ FORECASTER BERG