Tropical Discussion

Posted May 30, 2007
Updated August 19, 2013

axnt20 knhc 191049

Tropical weather discussion
NWS National Hurricane Center Miami FL
805 am EDT Mon Aug 19 2013

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 observations...radar...and meteorological

Based on 0600 UTC surface analysis and satellite imagery through
1015 UTC.

...Tropical waves...
tropical wave extends from 10n26w to a 1007 mb low near 14n27w
to 20n24w moving W at 10-15 kt. The wave is embedded within a
broad 700 mb trough S of 17n between 15w-32w and is located
within a broad low-level monsoonal gyre from 07n-20n between 20w-
37w. No significant convection is noted with the wave at this

Tropical wave extends from 14n67w to 23n63w moving W at 15 kt.
The wave remains embedded within a moisture maximum according to
total precipitable water imagery from 10n-21n between 60w-65w.
The wave also coincides with a weak 700 mb trough moving across
the NE Caribbean and portions of the SW north Atlc in the
vicinity of the northern extension of the wave axis. Isolated
moderate convection is from 19n-21n between 61w-65w.

Tropical wave extends from 15n85w to 23n83w moving W at 10-15
kt. The wave coincides with a weak 700 mb trough axis extending
from western Cuba to north-central Honduras with the strongest
relatively vorticity located over the open waters of the NW
Caribbean. Isolated moderate convection is occurring mostly near
the northern extent of the wave axis from 20n-24n between 84w-

...ITCZ/monsoon trough...
the monsoon trough extends from the African coast near 20n16w to
18n24w then from 10n27w to 07n30w to 07n41w. The intertropical
convergence zone axis extends from 07n41w to 09n53w. Scattered
moderate convection is from 15n-20n between 16w-19w...and from
03n-07n between 28w-33w. A surface trough is analyzed on the
western extent of the ITCZ axis from 09n62w to 15n59w. Isolated
moderate convection along with isolated showers are occurring
from 07n-15n between 49w-65w. Most of the strongest convection
is occurring over portions of inland northeastern Venezuela this


Gulf of Mexico...
a middle to upper level trough is noted on water vapor imagery
with axis extending from North Texas near 32n95w to a base over
east-central Mexico near 20n100w. To the east of this trough upper level ridge extends westward from over the SW
north Atlc into the eastern Gulf resulting in primarily
southerly upper level diffluent flow between 90w-96w. A surface
trough reflects the influence of the middle to upper levels
analyzed from the Mississippi River Delta near 29n90w SW to
26n95w then south to near 20n95w. Widely scattered showers and
isolated tstms are occurring within 120 nm either side of the
surface trough. The remainder of the Gulf is under the influence
of the northern extent of a tropical wave moving across the
western Caribbean Sea along 85w. Mid-level energy continues to
fracture northward due to the weakness in the mid-level ridging
over the basin that is generating widely scattered showers and
tstms between 83w-87w....including portions of the Florida
Straits. Otherwise...E-se winds prevail and are forecast to
remain generally below 20 kt for most of the week ahead. The
surface trough over the western Gulf is expected to drift slowly
westward and dissipate inland over southern Texas and eastern
Mexico late Monday into Tuesday.

Caribbean Sea...
an upper level low is centered over the NW Caribbean near 17n84w
and along with a tropical wave along 85w is generating widely
scattered showers and isolated tstms N of 20n between 83w-87w...
including the Yucatan Channel. The energy and moisture
associated with the tropical wave is expected to move westward
over the next 24 to 36 hours and influence the Yucatan Peninsula
as well as areas across the southern Gulf of Mexico. Farther upper level ridge axis extends from the tropical Atlc
over the central and eastern Caribbean along 15n. Water vapor
imagery indicates mostly dry air accompanies the ridge and
primarily low-level moisture and marginal middle to upper level
diffluence are generating isolated low-topped isolated showers
and tstms N of 17n E of 81w. A tropical wave along 66w remains a
Focal Point for some of this shower activity bringing increased
precipitation chances to the Puerto Rico and Hispaniola over the
next 24 to 48 hours. Also of note...a surface trough...likely an
extension of the ITCZ analyzed from 10n62w to 15n59w.
Widely scattered showers and tstms are occurring across the
Windward Islands and se Caribbean S of 15n E of 68w.

currently earlier convection has diminished with only a few
remaining isolated showers occurring the across the island this
morning. With an upper level diffluent environment remaining
over the island due to southwest to westerly flow aloft...and an
approaching tropical wave analyzed across the eastern Caribbean
Sea...isolated showers are expected to persist over the next few
days with stronger scattered convection expected to initiate
during the afternoon hours due to peak daytime heating and
instability. Any activity that forms will likely last into the
evening hours and diminish thereafter.

Atlantic Ocean...
a middle to upper level anticyclonic circulation is centered
over the SW north Atlc near 33n71w that is providing overall
stable conditions for the SW north Atlc W of 70w. Water vapor
imagery indicates this area remains dry aloft with satellite
imagery indicating isolated low-topped showers are occurring
primarily W of 50w...and more concentrated activity over the
Bahamas and areas within the Florida Straits this morning.
Otherwise...a 1022 mb high centered near 33n67w is further
providing overall fair conditions for much of the western Atlc.
Farther east...a middle to upper level low is centered near
27n52w that is generating a few isolated showers from 25n-29n
between 47w-53w.

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