AXNT20 KNHC 171801 
TWDAT 
 
Tropical Weather Discussion 
NWS National Hurricane Center Miami FL 
201 PM EDT Mon Jul 17 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 1200 UTC surface analysis and satellite imagery through 
1715 UTC. 
 
...SPECIAL FEATURES... 
 
A 1010 mb low pressure center is near 11N51W. Convective 
precipitation: Scattered moderate to isolated strong from 10N to 
12N between 51W and 53W. Environmental conditions are conducive for 
some development before the system reaches the Lesser Antilles late 
Tuesday or early Wednesday. Less favorable upper-level winds are 
expected to hinder additional development after that time. It is 
expected that this system may bring locally heavy rainfall and 
gusty winds to parts of the Lesser Antilles beginning on Tuesday. 
An Air Force Reserve reconnaissance aircraft is en route in order 
to investigate the situation. The chance for formation into a 
tropical cyclone during the next 48 hours is medium. Please refer 
to the latest Tropical Weather Outlook...MIATWOAT/ABNT20 KNHC... 
for more details. 
 
...TROPICAL WAVES... 
 
An Atlantic Ocean tropical wave is along 33W/34W from 20N 
southward. Convective precipitation: widely scattered moderate to 
isolated strong from 10N to 14N between 30W and 36W. 
 
An Atlantic Ocean tropical wave is along 55W/56W from 19N 
southward. Convective precipitation: isolated moderate from 12N to 
24N between 54W and 60W. 
 
A Caribbean Sea tropical wave is along 82W/83W from 23N in NW 
Cuba, southward. Convective precipitation: widely scattered to 
scattered moderate and isolated strong from 17N southward between 
80W and 86W, including interior sections and coastal waters of 
Nicaragua and Honduras. 
 
A SW Gulf of Mexico tropical wave is along 95W/96W from 22N 
southward. The wave is moving through southern Mexico, just to the 
west of the Isthmus of Tehuantepec of southern Mexico. Convective 
precipitation: Weakening precipitation and convective debris 
clouds are present from 24N southward between 90W and 96W. 
 
...ITCZ/MONSOON TROUGH... 
 
The Monsoon Trough passes through coastal sections of Senegal near 
14N17W to 14N24W, 09N37W, and 10N51W. Convective precipitation: 
scattered to numerous strong is in the coastal plains and coastal 
waters of Africa from 10N to 14N between 14W and 17W. Isolated 
moderate to locally strong from 08N to 10N between 12W and 14W in 
the coastal plains. Widely scattered moderate to isolated strong 
from 04N to 11N between 35W and 45W. Scattered moderate to strong 
from the Equator to 02S between 35W and 40W. 
 
...DISCUSSION... 
 
...THE GULF OF MEXICO... 
 
An upper level cyclonic circulation center is moving inland along 
the coast of Mexico near 21N97W. Cyclonic wind flow covers Mexico 
and the Gulf of Mexico from 17N to 25N between 89W and 106W. A 
weakening cyclonic circulation center is near 23N86W. Weakening 
precipitation and convective debris clouds are present from 24N 
southward between 90W and 96W. 
 
The surface pressure pattern is weak, with little gradient. 
 
Convective precipitation: rainshowers and thunder are in the 
coastal waters, and reaching land in some cases, from 27N 
northward between 83W for Florida and 95W for the upper Texas Gulf 
coast. rainshowers and thunder also are present in along the SW 
coast of Florida from 25N to 27N between 81W and 83W, and in the 
coastal plains of Texas from 27N to 28N between the coast and 98W. 
 
...THE CARIBBEAN SEA... 
 
Broad upper level anticyclonic wind flow covers the area that is 
from 18N southward, from the Yucatan Peninsula of Mexico and 
Guatemala eastward to 70W, and southeastward. Broad and weak 
cyclonic wind flow, and comparatively drier air in subsidence that 
is evident in water vapor imagery, cover the Caribbean Sea from 
70W eastward. Weak upper level cyclonic wind flow also covers the 
rest of the area, in the NW corner of the Caribbean Sea. 
 
The monsoon trough is along 09N/10N between 74W/75W in Colombia, 
beyond NW Costa Rica, into the eastern Pacific Ocean. Convective 
precipitation: isolated moderate from 12N southward between 75W 
and 80W. 
 
24-hour rainfall totals in inches, for the period that ended at 
17/1200 UTC, according to the PAN AMERICAN TEMPERATURE AND 
PRECIPITATION TABLES...MIATPTPAN/SXCA01 KNHC...are: 1.45 in 
Merida in Mexico, 0.17 in Guadeloupe, 0.10 in Bermuda, 0.07 in 
San Juan in Puerto Rico and in St. Thomas in the Virgin Islands, 
0.03 in Nassau in the Bahamas. a TRACE was reported in Freeport in 
the Bahamas, in Montego Bay in Jamaica, and in Trinidad. 
 
...HISPANIOLA... 
 
An upper level trough is in the Atlantic Ocean, to the north of 
Hispaniola, between 62W and 75W. Upper level anticyclonic wind 
flow, westerly at the moment, is in the Caribbean Sea to the south 
of Hispaniola. A surface ridge passes through the Atlantic Ocean 
near 28N61W, to 22N71W, to Hispaniola. 
 
SURFACE OBSERVATIONS...for Port-au-Prince in Haiti: VFR. for the 
DOMINICAN REPUBLIC: Barahona: VFR. Santo Domingo: earlier rain has 
ended for the moment. few towering cumulus clouds. La Romana: VFR. 
Punta Cana: VFR. Santiago: MVFR. ceiling 2200 feet. few 
cumulonimbus clouds. Puerto Plata: VFR. 
 
The GFS MODEL forecast for 250 mb shows that broad cyclonic wind 
flow will be spanning the area during the next 48 hours. The GFS 
MODEL forecast for 500 mb shows that E-to-SE wind flow will be 
moving across the area during the next 48 hours. It is possible 
that even NE wind flow may be present at the end of the 48-hour 
forecast period. The GFS MODEL forecast for 700 mb shows that at 
least one inverted trough, and possibly a second one, will be 
moving across Hispaniola, during the next 48 hours. Expect 
cyclonic wind flow. 
 
...THE ATLANTIC OCEAN... 
 
An upper level cyclonic circulation center is near 30N70W. 
Upper level cyclonic wind flow covers the area from 20N between 
62W and 75W. Convective precipitation: widely scattered moderate 
to isolated strong within 90 nm on either side of the line that 
passes through 32N64W, to 29N67W and 23N70W. isolated moderate to 
locally strong covers parts of the NW Bahamas from 24N northward 
between 77W and 80W. 
 
An upper level cyclonic circulation center is 32N50W. Upper level 
cyclonic wind flow covers the area from 23N northward between 40W 
and 57W. Convective precipitation: isolated moderate from 31N 
northward between 44W and 60W. 
 
Surface anticyclonic wind flow spans the area from 20N northward 
between Africa and 80W. A 1031 mb high pressure center is near 
34N43W. 
 
For additional information please visit 
http://www.hurricanes.gov/marine