Atlantic Tropical Weather Discussion (Text)

AXNT20 KNHC 260005

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
705 PM EST Sat Feb 25 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 
2315 UTC.


The Monsoon Trough passes through the coastal areas of Guinea near
10N14W to 03N16W. The ITCZ continues from 03N16W, curving to the
Equator along 25W and passing through 01N35W to 02N50W. Scattered
moderate isolated strong convection was noted within 90-120 NM 
N of the ITCZ between 31W and 50W.  



A flat mid-to upper level trough is moving across the eastern
United States and extends into the northern Gulf with generally 
westerly flow aloft. The flow was suppressing a ridge over the
southern Gulf. Moderate to strong subsidence was noted over the
Gulf becoming more pronounced over the Bay of Campeche. This
trough is supporting a weakening cold front which as of 2100 UTC 
extended from the Big Bend of Florida to 25N93W where it became a 
dissipating stationary front to 20N96W. A surface trough was 
located over the eastern Bay of Campeche extending from 22N95W
southeast to 19N92W. Generally fair conditions prevailed over the
Gulf with only scattered to locally broken low clouds in the 
vicinity of the cold front. Fresh N to NE winds of 15-20 KT were 
occurring behind the cold front generally W of 90W. Light and 
variable to westerly winds prevailed elsewhere. The cold front is 
expected to move SE through the Gulf tonight with high pressure 
building eastward across the southern U.S. Return SE flow begins 
over the Gulf W of 90W by Sun afternoon and spreads over most of 
the Gulf by early Mon. 


A fairly sharp mid-to-upper level trough passes through the 
Windward Passage, into the SW corner of the basin. Very strong
subsidence was noted in the wake of the trough and elsewhere over
the basin W of 65W. W weak surface ridge extended from 20N60W
through the northern Leeward Islands to 15N75W. As of 2100 UTC a
weak surface trough was analyzed from the Gulf of Honduras to
19N80W. This weak ridge maintained sub-normal trade winds over 
the basin, generally around 10 kt. Patches of broken to overcast 
low and mid clouds with widely scattered showers were noted 
in the vicinity of the surface trough and elsewhere across the 
Caribbean Sea east of 70W, and north from 14N between 70W and 
76W. Trade winds should begin to increase on Sun as high pressure
builds north of the area with strong winds likely within 90 Nm of
the coast of Colombia Sun night into Mon. 


Water vapor imagery indicated very dry air/strong subsidence over
the entire island. This was confirmed by the 1200 UTC rawinsonde 
from Santo Domingo which showed a strong capping inversion at 623 
MB. Despite the dry air, orographic lift was sufficient to 
trigger an isolated thunderstorm over northern Dominican Republic.
Little change in overall conditions are anticipated through the 
remainder of the weekend. 


A deep layer trough extends through 32N66W to the SE Bahamas, 
through the Windward Passage, into the SW corner of the Caribbean 
Sea. The waning influence of this trough is providing limited 
support to a surface trough from 31N65W to 25N72W and a 
dissipating stationary front from 31N62W to 24N65W. Broken to 
overcast low and mid clouds with embedded showers were noted 
within 45-50 NM either side of the surface trough and within 180 
NM east of the stationary front N of 26N. 

Further east, an upper level trough extends through 32N27W to
25N35W to 19N45W. Broad upper level cyclonic wind flow covers the
Atlantic Ocean elsewhere N of 18N and east of 30W. A stationary 
front extends through 32N37W to 27N45W to 22N55W. Broken to
overcast low clouds with embedded showers are possible within 240
NM northwest of the front N of 25N. 

A surface ridge extends from a 1030 mb high pressure center near 
37N41W, through 32N48W to 25N58W. Further east, another surface 
ridge extends from a 1028 mb high pressure center near 34N24W, to
26N35W to 20N60W.

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Page last modified: Sunday, 26-Feb-2017 00:05:30 UTC