[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 262349
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
749 PM EDT Sat Aug 26 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 1800 UTC surface analysis and satellite imagery through
2330 UTC.

...SPECIAL FEATURES...

Tropical Storm Harvey is centered near 29.1N 97.6W at 26/2100 UTC
or about 40 nm WNW of Victoria Texas and about 50 nm ESE of San
Antonio Texas. The system is stationary. Estimated minimum
central pressure is 990 mb. Maximum sustained wind speed is 55 kt
with gusts to 65 kt. Numerous moderate and isolated strong
convection is occurring within 60 nm of the center. Scattered
moderate and strong convection is seen elsewhere in the E
semicircle within 240 nm of the center. See the latest
Intermediate Public Advisory under AWIPS/WMO headers
MIATCPAT4/WTNT34 KNHC and the full Forecast/Advisory under
AWIPS/WMO headers MIATCMAT4/WTNT24 KNHC for more details.

An elongated area of low pressure is stretching across north-
central Florida continues to produce a large area of disorganized
cloudiness and thunderstorms extending from the southwest coast of
Florida northeastward into the western Atlantic. Although upper-
level winds are not particularly conducive, this system has the
potential to become a tropical or subtropical depression early
next week after it moves off the northeast coast of Florida on
Sunday. Regardless of tropical cyclone development, the low is
expected to cause heavy rain and increasing winds and rough surf
along the coasts of Georgia and the Carolinas through early next
week. This system has a a medium chance of tropical formation
within the next 48 hours.

...TROPICAL WAVES...

A tropical wave extends its axis from 25N24W to 14N27W, moving
slowly west at around 5-10 kt. The wave coincides with amplified
700 mb troughing in initial model field wind data. Infrared
satellite imagery shows a large area of Saharan dust to the north
of the wave to about 30N and west of the wave to about 40W. No
deep convection is associated with this feature at this time.

A tropical wave extends its axis from 22N51W to 12N50W, moving
west at around 10 kt. A broad cyclonic circulation is observed
along the wave's axis but not a defined low center has been found.
Initial global model guidance indicates weak 700 mb troughing in
conjunction with this wave. Scattered moderate convection is
present from 16N-20N between 47W-55W.

The northern extension of a tropical wave reaches the southern
portion of the Bay of Campeche south of 20N and along 95W. Global
model guidance shows modest 700 mb troughing in conjunction with
this wave. The convection related to this wave prevails inland
over southern Mexico and over the EPAC waters.

...ITCZ/MONSOON TROUGH...

The monsoon trough extends from 15N17W to 14N35W to 13N51W. The
ITCZ continues from 13N51W to 10N61W. Scattered moderate
convection is from 04N to 18N and east of 20W.

...DISCUSSION...

GULF OF MEXICO...

The primary concern for the northwestern Gulf of Mexico is T.S.
Harvey, currently stationary over southern Texas. The southeastern
portion of the system is expected to remain over water and allow
Harvey to continue generating winds and heavy rains along the
Texas and Louisiana Coasts. To the east, a 1012 mb low is centered
over west-central Florida near 28N82W. A surface trough extends
from the low to 29N87W. This low was described in the section
above. Scatterometer data depicts variable gentle to moderate
winds across the basin except near T.S. Harvey. As
Harvey impacts the northwest Gulf waters and coastal Texas for
the next several days, the troughing and low pressure across the
eastern Gulf waters and Florida peninsula are expected to maintain
unsettled conditions across the region as this system moves
northeast into the western Atlantic on Sunday night or Monday.

CARIBBEAN SEA...

The only area with scattered moderate convection over the basin
remains in the proximity of the monsoon trough that extends along
10N. To the east, a surface trough extends from 19N64W to 11N65W.
Scatterometer data depicts gentle to moderate trades across most
of the basin except over the waters north of Colombia and over
the Gulf of Honduras. In these areas moderate to fresh easterlies
prevail. This overall synoptic pattern is expected to persist
through Monday.

...HISPANIOLA...

An upper-level low centered northwest of the island could trigger
isolated afternoon showers and thunderstorms this weekend during
the time of maximum daytime heating and instability, along with
local sea breeze effects. Otherwise, a relatively dry weather
pattern is expected during the next few days.

ATLANTIC OCEAN...

Tow tropical waves are moving across the basin. Refer to the
section above for details. Upper-level ridging and an overall
divergent upper-level pattern prevails over the western Atlantic
generating scattered showers and thunderstorms mainly west of 70W.
To the east, an upper-level low is centered near 30N48W and has
induced a weak surface trough that extends from 30N51W to 28N54W. The
remainder of the central and eastern Atlantic remains under the
influence of a surface ridge anchored by a broad 1028 mb high
centered near 40N36W.

For additional information please visit
http://www.hurricanes.gov/marine

$$

ERA
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