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KF5JRV > WX 16.09.18 15:46l 104 Lines 4049 Bytes #999 (0) @ NA
BID : 21368_KF5JRV
Read: GUEST
Subj: NWS NHC Atlantic WX - Sept 16
Path: IW8PGT<CX2SA<SV1CMG<PI8BDG<AB0AF<VE3UIL<N9PMO<N9LCF<KF5JRV
Sent: 180916/1419Z 21368@KF5JRV.#NWAR.AR.USA.NA BPQ6.0.16
431
WTNT43 KNHC 160843
TCDAT3
Tropical Storm Helene Discussion Number 36
NWS National Hurricane Center Miami FL AL082018
500 AM AST Sun Sep 16 2018
Helene's cloud pattern is certainly looking less and less like a
tropical cyclone this morning. Based on conventional satellite
imagery and AMSU data, Helene is quickly undergoing an extratropical
transition, and this dynamic process is expected to be completed
later today, as the cyclone moves away from the Azores. The
initial intensity is lowered to 45 kt, and is based primarily on
2326 UTC ASCAT-A wind retrievals. Cold (22C) sea surface
temperatures and strong westerly shear will continue to disrupt
Helene's vertical structure and should cause the cyclone to
complete the extratropical transition in 12 hours, or sooner.
The initial motion is estimated to be northeastward, or 50/22 kt,
within the ferocious mid-latitude westerlies. The global models are
in remarkably good agreement with Helene accelerating northeastward
and becoming absorbed in a large baroclinic zone extending over
northern United Kingdom in 72 hours, and the official forecast
reflects this scenario.
Earlier 2326 UTC METOP-A ASCAT scatterometer data indicated that the
34 kt and 50 kt wind radii, particularly in NW and NE quadrants, had
decreased considerably. Accordingly, an adjustment was made on this
advisory.
Interests in those locations should consult products from their
local meteorological service for information about potential impacts
from Helene. Local forecasts and warnings for the UK can be found on
the website of the UK Met Office athttps://www.metoffice.gov.uk/.
Local forecasts and warnings for Ireland can be found on the website
of Met Eireann at https://www.met.ie/.
FORECAST POSITIONS AND MAX WINDS
INIT 16/0900Z 42.5N 28.4W 45 KT 50 MPH
12H 16/1800Z 44.5N 24.7W 45 KT 50 MPH...POST-TROPTRATROP
24H 17/0600Z 47.4N 18.1W 45 KT 50 MPH...POST-TROPTRATROP
36H 17/1800Z 50.8N 10.8W 45 KT 50 MPH...POST-TROPTRATROP
48H 18/0600Z 55.1N 3.7W 40 KT 45 MPH...POST-TROPTRATROP
72H 19/0600Z...ABSORBED BY A FRONT
$$
Forecaster Roberts
075
WTNT45 KNHC 160844
TCDAT5
Tropical Storm Joyce Discussion Number 15
NWS National Hurricane Center Miami FL AL102018
500 AM AST Sun Sep 16 2018
What's left of the Joyce's associated deep convection is now
displaced about 80 miles to the north-northeast of the elongated
surface circulation. There still may be some 35 kt winds in a
small area of deep convection where the coldest cloud tops (-65C)
are observed, therefore, the initial intensity is held at 35 kt for
this advisory.
There is no change to the intensity forecast philosophy. The
surrounding environment is forecast to remains quite unfavorable
during the next 24 hours, although the warm 27C oceanic temperatures
could slightly counteract the negative effects of the harsh vertical
shear pattern. Afterward, decreasing sea surface temperatures, a
more stable thermodynamic air mass, along with the stiff shear, is
forecast to induce gradual weakening and, ultimately, dissipation in
4 days.
The initial motion is estimated to be east-northeastward, or 075/15
kt. The cyclone is embedded within the same mid-tropospheric
steering flow as Tropical Storm Helene, and Joyce should move
east-northeastward to eastward today. Through day 3, Joyce should
turn southeastward to south-southwestward around the eastern
periphery of a subtropical ridge to its west as a vertically
shallow system. The NHC forecast is similar to the previous
advisory, and is based on the better-performing consensus aids.
FORECAST POSITIONS AND MAX WINDS
INIT 16/0900Z 34.0N 36.1W 35 KT 40 MPH
12H 16/1800Z 34.5N 33.4W 30 KT 35 MPH
24H 17/0600Z 34.6N 30.1W 30 KT 35 MPH
36H 17/1800Z 34.1N 27.8W 30 KT 35 MPH
48H 18/0600Z 32.9N 26.8W 25 KT 30 MPH
72H 19/0600Z 30.7N 28.5W 25 KT 30 MPH
96H 20/0600Z...DISSIPATED
$$
Forecaster Roberts
73 de Scott KF5JRV
Pmail: KF5JRV@KF5JRV.#NWAR.AR.USA.NA
email: KF5JRV@ICLOUD.COM
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