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- Fri, 27 Sep 2024 20:35:28 +0000: Atlantic Post-Tropical Cyclone Helene Advisory Number 18 - Atlantic Post-Tropical Cyclone Helene Advisory Number 18
511
WTNT34 KNHC 272035
TCPAT4
BULLETIN
Post-Tropical Cyclone Helene Advisory Number 18
NWS National Hurricane Center Miami FL AL092024
400 PM CDT Fri Sep 27 2024
...HELENE STILL PRODUCING CATASTROPHIC FLOODING OVER PORTIONS OF
THE SOUTHERN APPALACHIANS AND TENNESSEE VALLEY...
...FUTURE ADVISORIES WILL BE ISSUED BY THE WEATHER PREDICTION
CENTER...
SUMMARY OF 400 PM CDT...2100 UTC...INFORMATION
----------------------------------------------
LOCATION...37.5N 85.5W
ABOUT 50 MI...80 KM SSE OF LOUISVILLE KENTUCKY
MAXIMUM SUSTAINED WINDS...35 MPH...55 KM/H
PRESENT MOVEMENT...NNW OR 330 DEGREES AT 17 MPH...28 KM/H
MINIMUM CENTRAL PRESSURE...984 MB...29.06 INCHES
WATCHES AND WARNINGS
--------------------
There are no coastal watches or warnings in effect.
For storm information specific to your area, please monitor
products issued by your local National Weather Service forecast
office.
DISCUSSION AND OUTLOOK
----------------------
At 400 PM CDT (2100 UTC), the center of Post-Tropical Cyclone Helene
was located near latitude 37.5 North, longitude 85.5 West. The
post-tropical cyclone is moving toward the north-northwest near 17
mph (28 km/h). A slowdown in forward speed is expected, and the
system is forecast to stall over the Tennessee Valley late tonight
and through the weekend.
Maximum sustained winds are near 35 mph (55 km/h) with higher gusts.
Continued weakening is expected during the next couple of days.
The estimated minimum central pressure is 984 mb (29.06 inches).
HAZARDS AFFECTING LAND
----------------------
Key Messages for Helene can be found in the Tropical Cyclone
Discussion under AWIPS header MIATCDAT4 and WMO header WTNT44 KNHC
and on the web at hurricanes.gov/text/MIATCDAT4.shtml
RAINFALL: Over portions of the central and southern Appalachians,
Helene is expected to produce additional rainfall amounts of 1 to 2
inches leading to widespread total rainfall accumulations of 6 to 12
inches, with isolated totals exceeding 20 inches. This rainfall will
result in catastrophic and potentially life-threatening flash and
urban flooding, along with record level river flooding in many
instances. Numerous significant landslides are expected in steep
terrain across the southern Appalachians. Elsewhere, 1 to 3 inches
of rainfall is expected across portions of the Ohio Valley through
Sunday evening.
For a complete depiction of forecast rainfall associated with
Tropical Storm Helene, please see the National Weather Service Storm
Total Rainfall Graphic, available at
hurricanes.gov/graphics_at4.shtml?rainqpf and the Flash Flood Risk
graphic at hurricanes.gov/graphics_at4.shtml?ero.
For a list of rainfall observations (and wind reports) associated
this storm, see the companion storm summary at WBCSCCNS4 with the
WMO header ACUS44 KWBC or at the following link:
www.wpc.ncep.noaa.gov/discussions/nfdscc4.html.
TORNADOES: Isolated tornadoes are possible this afternoon and
evening over southern Virginia and northeast North Carolina.
SURF: Swells generated by Helene will affect the coasts of Georgia
and the Carolinas during the next day or so. These swells are
likely to cause life-threatening surf and rip current conditions.
Please consult products from your local weather office.
NEXT ADVISORY
-------------
This is the last public advisory issued by the National Hurricane
Center on Helene. Future information on this system can be
found in Public Advisories issued by the Weather Prediction Center
beginning at 1000 PM CDT, under AWIPS header TCPAT4, WMO
header WTNT34 KWNH, and on the web at www.hurricanes.gov.
Rainfall forecasts for the United States can always be found at
https://www.wpc.ncep.noaa.gov/qpf/qpf2.shtml
and outlooks of flash flood risks can be found at
https://www.wpc.ncep.noaa.gov/qpf/excessive_rainfall_outlook_ero.php
.
$$
Forecaster Cangialosi
- Fri, 27 Sep 2024 20:34:58 +0000: Atlantic Post-Tropical Cyclone HELENE Forecast/Adv... - Atlantic Post-Tropical Cyclone HELENE Forecast/Advisory Number 18 NWS NATIONAL Hurricane CENTER MIAMI FL AL092024 2100 UTC FRI SEP 27 2024 POST-TROPICAL Cyclone CENTER LOCATED NEAR 37.5N 85.5W AT 27/2100Z POSITION ACCURATE WITHIN 30 NM PRESENT MOVEMENT TOWARD THE NORTH-NORTHWEST OR 330 DEGREES AT 15 KT ESTIMATED MINIMUM CENTRAL PRESSURE 984 MB MAX SUSTAINED WINDS 30 KT WITH GUSTS TO 40 KT. WINDS AND SEAS VARY GREATLY IN EACH QUADRANT. RADII IN NAUTICAL MILES ARE THE LARGEST RADII EXPECTED ANYWHERE IN THAT QUADRANT. REPEAT...CENTER LOCATED NEAR 37.5N 85.5W AT 27/2100Z AT 27/1800Z CENTER WAS LOCATED NEAR 36.7N 84.9W FORECAST VALID 28/0600Z 37.9N 87.0W...POST-TROP/EXTRATROP MAX WIND 25 KT...GUSTS 35 KT. FORECAST VALID 28/1800Z 37.7N 87.2W...POST-TROP/EXTRATROP MAX WIND 20 KT...GUSTS 30 KT. FORECAST VALID 29/0600Z 37.5N 87.3W...POST-TROP/EXTRATROP MAX WIND 20 KT...GUSTS 30 KT. FORECAST VALID 29/1800Z 37.3N 87.0W...POST-TROP/EXTRATROP MAX WIND 20 KT...GUSTS 30 KT. FORECAST VALID 30/1800Z...DISSIPATED REQUEST FOR 3 HOURLY SHIP REPORTS WITHIN 300 MILES OF 37.5N 85.5W THIS IS THE LAST FORECAST/Advisory ISSUED BY THE NATIONAL HURRICANE CENTER ON THIS SYSTEM. FUTURE INFORMATION ON THIS SYSTEM CAN BE FOUND IN FORECAST/ADVISORIES ISSUED BY THE WEATHER PREDICTION CENTER BEGINNING AT 0300 UTC, UNDER AWIPS HEADER TCMAT4, WMO HEADER WTNT24 KWNH, AND ON THE WEB AT WWW.HURRICANES.GOV. RAINFALL FORECASTS FOR THE UNITED STATES CAN ALWAYS BE FOUND AT HTTPS://WWW.WPC.NCEP.NOAA.GOV/QPF/QPF2.SHTML AND OUTLOOKS OF FLASH FLOOD RISKS CAN BE FOUND AT HTTPS://WWW.WPC.NCEP.NOAA.GOV/QPF/EXCESSIVE_RAINFALL_OUTLOOK_ERO.PHP . $$ FORECASTER CANGIALOSI
539
WTNT24 KNHC 272034
TCMAT4
POST-TROPICAL CYCLONE HELENE FORECAST/ADVISORY NUMBER 18
NWS NATIONAL HURRICANE CENTER MIAMI FL AL092024
2100 UTC FRI SEP 27 2024
POST-TROPICAL CYCLONE CENTER LOCATED NEAR 37.5N 85.5W AT 27/2100Z
POSITION ACCURATE WITHIN 30 NM
PRESENT MOVEMENT TOWARD THE NORTH-NORTHWEST OR 330 DEGREES AT 15 KT
ESTIMATED MINIMUM CENTRAL PRESSURE 984 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 37.5N 85.5W AT 27/2100Z
AT 27/1800Z CENTER WAS LOCATED NEAR 36.7N 84.9W
FORECAST VALID 28/0600Z 37.9N 87.0W...POST-TROP/EXTRATROP
MAX WIND 25 KT...GUSTS 35 KT.
FORECAST VALID 28/1800Z 37.7N 87.2W...POST-TROP/EXTRATROP
MAX WIND 20 KT...GUSTS 30 KT.
FORECAST VALID 29/0600Z 37.5N 87.3W...POST-TROP/EXTRATROP
MAX WIND 20 KT...GUSTS 30 KT.
FORECAST VALID 29/1800Z 37.3N 87.0W...POST-TROP/EXTRATROP
MAX WIND 20 KT...GUSTS 30 KT.
FORECAST VALID 30/1800Z...DISSIPATED
REQUEST FOR 3 HOURLY SHIP REPORTS WITHIN 300 MILES OF 37.5N 85.5W
THIS IS THE LAST FORECAST/ADVISORY ISSUED BY THE NATIONAL HURRICANE
CENTER ON THIS SYSTEM. FUTURE INFORMATION ON THIS SYSTEM CAN BE
FOUND IN FORECAST/ADVISORIES ISSUED BY THE WEATHER PREDICTION CENTER
BEGINNING AT 0300 UTC, UNDER AWIPS HEADER TCMAT4, WMO HEADER
WTNT24 KWNH, AND ON THE WEB AT WWW.HURRICANES.GOV.
RAINFALL FORECASTS FOR THE UNITED STATES CAN ALWAYS BE FOUND AT
HTTPS://WWW.WPC.NCEP.NOAA.GOV/QPF/QPF2.SHTML
AND OUTLOOKS OF FLASH FLOOD RISKS CAN BE FOUND AT
HTTPS://WWW.WPC.NCEP.NOAA.GOV/QPF/EXCESSIVE_RAINFALL_OUTLOOK_ERO.PHP
.
$$
FORECASTER CANGIALOSI
- Fri, 27 Sep 2024 20:35:58 +0000: Atlantic Post-Tropical Cyclone Helene Discussion Number 18 - Atlantic Post-Tropical Cyclone Helene Discussion Number 18
367
WTNT44 KNHC 272035
TCDAT4
Post-Tropical Cyclone Helene Discussion Number 18
NWS National Hurricane Center Miami FL AL092024
400 PM CDT Fri Sep 27 2024
Helene has been producing catastrophic flooding over portions of
the southeast U.S. and southern Appalachians, and the associated
heavy rains are shifting westward into the Ohio and Tennessee
Valleys. Satellite images and surface observations indicate that
Helene has completed extratropical transition, and the initial
intensity is set at 30 kt.
The cyclone is moving to the north-northwest at 15 kt. A slowdown
is expected tonight, and the cyclone is forecast to stall over the
Tennessee Valley this weekend, likely resulting in continued and
prolonged rainfall.
This is the last tropical cyclone discussion issued by the
National Hurricane Center on Helene. Future information on
this system can be found in discussions issued by the Weather
Prediction Center beginning at 1000 PM CDT, under AWIPS header
TCDAT4, WMO header WTNT44 KWNH, and on the web at
www.hurricanes.gov.
Rainfall forecasts for the United States can always be found at
https://www.wpc.ncep.noaa.gov/qpf/qpf2.shtml
and outlooks of flash flood risks can be found at
https://www.wpc.ncep.noaa.gov/qpf/excessive_rainfall_outlook_ero.php
.
KEY MESSAGES:
1. Historic, catastrophic and life-threatening flash and urban
flooding, including numerous major landslides, will continue across
portions of the southern Appalachians through this evening, followed
by gradual improvement tonight and into Saturday. Widespread
serious river flooding is ongoing, some of which will be major to
record breaking.
2. There is a possibility of long-duration power outages in
portions of the southeast U.S. If you use a generator, be sure it
is placed outside at least 20 feet away from doors, windows, and
garages to avoid deadly carbon monoxide poisoning.
3. Use caution after the system passes as deadly hazards remain
including downed power lines and flooded areas.
FORECAST POSITIONS AND MAX WINDS
INIT 27/2100Z 37.5N 85.5W 30 KT 35 MPH...POST-TROPICAL
12H 28/0600Z 37.9N 87.0W 25 KT 30 MPH...POST-TROP/EXTRATROP
24H 28/1800Z 37.7N 87.2W 20 KT 25 MPH...POST-TROP/EXTRATROP
36H 29/0600Z 37.5N 87.3W 20 KT 25 MPH...POST-TROP/EXTRATROP
48H 29/1800Z 37.3N 87.0W 20 KT 25 MPH...POST-TROP/EXTRATROP
60H 30/0600Z...DISSIPATED
$$
Forecaster Cangialosi