AXNT20 KNHC 300945
Tropical Weather Discussion
NWS National Hurricane Center Miami FL
545 AM EDT Sat Sep 30 2017
Tropical Weather Discussion for North America, Central America
Gulf of Mexico, Caribbean Sea, northern sections of South
America, and Atlantic Ocean to the African coast from the
Equator to 32N. The following information is based on satellite
imagery, weather observations, radar and meteorological analysis.
Based on 0600 UTC surface analysis and satellite imagery through
Tropical Storm Maria is centered near 39.6N 50.5W at 30/0900 UTC
or about 440 nm SSE of Cape Race Newfoundland moving E-NE at 28
kt. Estimated minimum central pressure is 988 mb. Maximum
sustained wind speed is 50 kt with gusts to 60 kt. Scattered
moderate convection is from 33N-41N between 47W-53W. See the
latest NHC Forecast/Advisory under AWIPS/WMO headers MIATCMAT5/
WTNT25 KNHC for more details.
Post-Tropical Cyclone Lee is centered near 46.7N 35.6W at 30/0900
UTC or about 645 nm NNW of the Azores moving NE at 44 kt.
Estimated minimum central pressure is 998 mb. Maximum sustained
wind speed is 45 kt with gusts to 55 kt. See the latest NHC
Forecast/Advisory under AWIPS/WMO headers MIATCMAT4/WTNT24 KNHC
for more details.
A tropical wave extends from 09N68W to 22N64W moving W at 5-10
kt. An upper level low is centered to the W of the wave over
eastern Hispaniola and continues interacting favorably with the
wave producing scattered moderate convection from 13N-21N between
57W-68W…including the Lesser Antilles…the US/UK Virgin
Islands…and Puerto Rico. The upper level low will retrograde
westward through early Sunday and remain in a favorable position
to produce active convection across the Leeward Islands…Puerto
Rico…and portions of Hispaniola on Saturday into early Sunday.
A tropical wave extends from 08N35W to 19N39W moving W at 10-15
kt. The wave coincides with 700 mb troughing 36W-43W and
continues moving beneath the influence of an upper level low
centered near 18N42W. Given these features at all levels…widely
scattered moderate convection is occurring from 04N-15N between
26W-37W. Isolated moderate convection is from 15N-18N between
The monsoon trough extends from the African coast near 07N11W to
09N24W. The Intertropical Convergence Zone axis extends from
09N24W to 09N30W to 05N41W to 04N52W. Scattered moderate
convection is from 05N-12N between 11W-26W.
GULF OF MEXICO…
A broad area of lower surface pressure is analyzed across the
eastern Gulf of Mexico…Florida peninsula…and adjacent coastal
waters of the SW North Atlc this morning. Much of this area of
lower pressure is focused on a surface trough extending from N of
the Bahamas near 30N76W into a weak 1011 mb low centered across
the central Florida peninsula near 28N81W to 27N83W in the
eastern Gulf and falls within influence of a middle to upper level
low centered near 26N86W. The upper level low continues to advect
moisture northward from the NW Caribbean Sea over Cuba…the
Florida Straits…and Florida peninsula. Regardless of possible
tropical cyclone development over this region…the upper level
low and troughing will produce areas of heavy rainfall across the
Florida peninsula and adjacent Gulf waters during the next few
days. Elsewhere…across the SW Gulf waters…a surface trough is
analyzed from 18N94W to 25N98W providing focus for scattered
showers and strong tstms generally S of 24N W of 93W.
Active convection will continue with the tropical wave moving
across the eastern Caribbean as an upper level low noted on water
vapor imagery over eastern Hispaniola moves W and generally in
tandem with the wave during the next 24-36 hours. Much of the wave
related moisture is expected to shift NW across the NE Caribbean
and into the SW North Atlc by late Saturday into early Sunday.
Elongated low pressure also extends across the Yucatan Channel
region then southward across the Gulf of Honduras and portions of
Central America. Dynamic lift associated with an upper level low
centered near 17N85W and a divergent environment over Central
America is forcing active convection across much of the NW
Caribbean S of 22N W of 81W…and portions of Central America
from Honduras westward to Guatemala and southern Mexico.
Otherwise…moderate to fresh E-SE trades will persist through
Currently the island falls under the influence of an upper level
low centered near 19N70W. The upper level low will continue
moving westward as a tropical wave…across the eastern Caribbean
Sea at this time…will begin to increase cloudiness and the
probability of precipitation Saturday and Saturday night. While
deeper convection remains generally south and east of Puerto Rico
at this time…the leading edge of isolated shower and tstm
activity remains S of the Mona Passage and adjacent southeastern
coastal waters this morning.
A broad plume of moisture is being pulled northward across the
waters N of the Bahamas by a middle to upper level low centered
over the NE Gulf of Mexico. The upper level low and surface
troughing extending from 30N76W to a 1012 mb low centered near
28N81W and supports scattered showers and isolated tstms
generally N of 26N W of 74W. To the northeast…a cold front
extends from 32N60W to 29N70W and becomes stationary into a 1014
mb low centered off the South Carolina coast near 33N78W.
Scattered showers and isolated tstms are occurring within 120 nm
either side of the front W of 60W. Elsewhere…surface ridging
prevails across much of the remainder of the central and eastern
Atlc anchored by 1026 mb high centered near 34N31W.
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