139
axnt20 knhc 231128
twdat
Tropical weather discussion
NWS TPC/National Hurricane Center Miami FL
705 am EST sun Nov 23 2008
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...meteorological analysis...weather
observations...and radar.
Based on 0600 UTC surface analysis and satellite imagery through
1045 UTC.
...Tropical waves...
tropical wave is over the E Caribbean along 68w/69w S of 18n
moving W near 10 kt. Satellite imagery indicates that this wave
coincides with an inverted-v pattern in cloud coverage...where
wavetrak product indicates a maximum in low level cyclonic
circulation. Additionally...a maximum in deep layer moisture
coincides with this wave based on total precipitable water
product from CIMSS. Upper air time-height analysis for
Curacao...located in the Netherlands Antilles near 12n69w...
depicts a recent and subtle veering of the mean low/mid-level
flow from NE to se...suggesting that this wave is likely in the
vicinity of Curacao. Scattered moderate convection is occurring
within 150 nm either side of the wave axis S of 16n.
...The ITCZ...
the ITCZ axis is analyzed along 9n12w 7n24w 9n32w 8n44w 6n57w.
Scattered moderate/isolated strong convection is from 4n-11n
between 14w-21w. Scattered moderate convection is from 5n-12n
between 26w-39w. Scattered moderate convection is also from
6n-10n between 42w-48w.
...Discussion...
Gulf of Mexico...
strong westerly upper level winds cover the Gulf region. At the
surface...a surface trough over the W Gulf extends from 25n97w
to 23n97w to 21n96w. Low level convergence is supporting
isolated showers within 60 nm either side of the surface trough.
Over the N and E Gulf region...a modified Continental polar
airmass is in place...where temperatures remain below seasonal
averages. This airmass is being supported by a 1033 mb surface
high over South Carolina near 33n81w...with an associated
surface ridge extending across the NE Gulf. As cooler air is
being advected over the relatively warmer Gulf waters...weak low
level instability is supporting scattered stratocumulus clouds
across the Gulf mainly N of 24n W of 84w. However...subsidence
and stable atmospheric conditions higher in the atmosphere are
inhibiting deep convection across the Gulf region.
Additionally...strong N to NE surface winds are blowing through
The Isthmus of Tehuantepec resulting in gale force winds in the
E Pacific region. These winds are forecast to diminish below
gale force at 24/0000 UTC.
Caribbean Sea...
in the SW Caribbean...low level convergence in the vicinity of a
1008 mb surface low N of Panama is interacting with deep layer
moisture over the W Caribbean to result in scattered showers and
thunderstorms over the Caribbean S of 13n W of 76w...including
portions of Costa Rica...Panama...and S Nicaragua. Development
of this system...if any...should be slow to occur due its
interaction with land. However...heavy rainfall causing
localized flooding will be possible over much of Panama...Costa
Rica...and Nicaragua during the next couple of days. This shower
and thunderstorm activity is being enhanced by upper level
diffluence in the vicinity of an upper ridge present over the W
Caribbean...with the axis of this upper ridge extending from N
Colombia near 11n73w to 16n81w to the NW Caribbean near 19n84w.
Also...a weakening surface cold front in the NW Caribbean
extends from 21n81w to E Cuba near 21n77w...with scattered
showers within 60 nm of this front. Over the E Caribbean...upper
level divergence is interacting with deep layer moisture to
support scattered showers and thunderstorms S of 16n between
65w-74w. This activity is being enhanced by low level
convergence associated with the tropical wave along 68w/69w
discussed in the tropical waves section above. Also...for
locations N of 14n between 69w-75w in the E Caribbean...NE to E
surface winds of 20 to 30 kt are forecast to occur through
Monday night...with gusts to gale force across the Windward
Passage.
Atlantic Ocean...
a broad upper level trough over the W Atlc is supporting a
surface cold front that extends from E Cuba near 21n77w to
26n62w to 32n56w to N of the discussion area. Isolated showers
are occurring within 60 nm either side of this cold front. To
the W of this cold front...a modified Continental polar airmass
is in place...with temperatures below seasonal averages across
Florida and scattered stratocumulus clouds between this front
and the coast of the se conus. This airmass is being supported
by a 1033 mb surface high over South Carolina near 33n81w.
Farther to the E...a surface trough extends from 28n58w to a
1017 mb surface low near 26n58w to 22n57w...with another surface
trough extending from 16n59w to a 1010 mb surface low near
15n53w to 14n47w. Isolated showers are occurring within 60 nm of
these surface lows and surface troughs. To the E...an upper
trough is present over the E Atlc N of 17n E of 43w with an
upper low near 30n35w. An associated surface trough extends from
a 1013 mb surface low near 23n35w to 21n32w to 18n36w. Low level
convergence near the surface trough and surface low is
supporting scattered showers from 21n-27n between
26w-36w...which are being enhanced by upper level divergence in
the vicinity of a mid/upper-level wind speed maximum and
atmospheric instability in the vicinity of the upper trough and
upper low.
$$
Cohen
| 