779 axnt20 knhc 042342 twdat

Tropical weather discussion  
NWS TPC/National Hurricane Center Miami FL
705 PM EST Thu Dec 04 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 1800 UTC surface analysis and satellite imagery through 
2315 UTC.
...The ITCZ...
the ITCZ axis is centered along 7n12w 3n30w 6n45w into French Guiana 
and Suriname. Scattered moderate/isolated strong convection is 
within 200 nm south of axis between 27w-34w. Similar convective 
activity is over Liberia and near 5n13w.  
...Discussion...
Gulf of Mexico...
strong southwesterly flow aloft covers the Gulf region and the 
Florida Peninsula...as a deep layered trough moves eastward over the 
E conus. The attendant cold front is moving southeastward across the 
Gulf...stretching from the Florida Panhandle to a 1018 mb sfc low 
located near 24n95w. At this point...the front continues SW entering 
Mexico just south of Tampico which is currently reporting gusty 
winds up to 28 kt. Low level convergence in the vicinity of this 
cold front...combined with atmospheric lift in moist southwesterly 
flow aloft...is supporting scattered showers and isolated tstms 
along the frontal boundary. An earlier ascat pass indicated nly 
winds of 20 to 30 kt behind the front. A relatively cooler and drier 
airmass is noted in the wake of the cold front. Over the SW Gulf...a 
surface trough runs from 21n95w to 19n93w and is generating some 
shower activity over the Bay of Campeche. Subsidence and resultant 
dry air is inhibiting deep convection over the se Gulf...where 
generally fair weather prevails. Over the next day...the cold front 
is forecast to continue moving southeastward over the Gulf...but is 
expected to slow its progress as the strongest upper level energy 
lifts northeast of the Gulf region. Additionally...strong N surface 
winds are forecast to blow through The Isthmus of Tehuantepec 
resulting in a gap wind event with gale force in the east Pacific 
region beginning late tonight.
Caribbean Sea...
a stationary front extending over central Cuba and the NW Caribbean 
should dissipate tonight. Isolated showers are along the frontal 
boundary. A sfc trough is along 77w south of 17n...and is forecast 
to move inland over Central America tonight and early Fri. A 1010 mb 
low has developed over the SW Caribbean close to 9n80w. The cloud 
pattern is exhibiting some cyclonic circulation with scattered 
moderate convection near the low center. Puerto Limon in Costa Rica 
has reported occasionally heavy rain. Aloft...an upper-level high is 
centered south of the eastern tip of Dominican Republic near 
16n68w...with an upper ridge covering the E and central Caribbean 
including the Lesser Antilles. Upper level diffluence SW of the 
upper high is supporting convection over the SW Caribbean. Strong 
swly upper level flow is noted across N Central America...the NW 
Caribbean and Cuba. These winds are advecting mid/upper level 
moisture from the epac into the Caribbean Sea. Patches of low level 
moisture carried by the trade winds continue to move across the 
eastern Caribbean producing intervals of cloudiness and a few 
showers.   
Atlantic Ocean...
SW to W winds aloft continues to increase over the W Atlc as the 
deep layered trough over the E conus progresses eastward. A surface 
trough is E of the Florida Peninsula along 80w from 26n to 30n. 
Mainly low topped clouds are near the trough. Farther to the E...a 
cold front enters the forecast area near 31n57w then continues SW to 
the central Bahamas where it becomes stationary. Low level 
convergence is supporting isolated showers within 60 nm either side 
of the frontal boundary. E of the frontal system...the flow aloft is 
more amplified...with an upper ridge axis extending from the NE 
Caribbean to beyond Bermuda and a sharp upper-level trough N of 14n 
between 30w-50w. A jet stream branch with core winds of 70-90 kt is 
just ahead of the trough axis and GOES from 20n39w to beyond 33n35w. 
This upper trough is associated with a surface trough extending from 
a 1011 mb surface low near 28n48w to 31n45w to another 1011 mb 
surface low situated near 26n43w to 21n46w. A well defined swirl of 
low clouds is associated with the first sfc low while the second one 
is dissipating. Over the E Atlc...subsidence and fair weather 
prevail thanks to a surface ridge extending from a 1027 mb high 
located around midway between the Azores and the Madeira islands. 
Farther to the S...an upper-level high centered just south of the 
Cape Verde Islands extends a ridge nwd over the discussion area. 
$$
Gr.







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