[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 170538
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
205 AM EDT FRI JUL 17 2015

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 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
0530 UTC.

...TROPICAL WAVES...

A TROPICAL WAVE IS OVER THE CENTRAL CARIBBEAN WITH AXIS
APPROXIMATELY ALONG 75W AND FROM 10N TO 19N...MOVING W AT 20-25
KT DURING THE LAST 24 HOURS. SSMI TPW IMAGERY DEPICT A MODERATE
MOIST AIRMASS ASSOCIATED WITH THIS WAVE PREVAILING ACROSS THE
NORTHERN PORTION OF THE WAVE AND EXTENDING ACROSS THE E
CARIBBEAN MAINLY N OF 15N. SAHARAN DUST IS ALSO PREVAILING
ACROSS THIS AREA THUS NO SIGNIFICANT CONVECTION IS OBSERVED AT
THIS TIME.

...ITCZ/MONSOON TROUGH...

THE MONSOON TROUGH EXTENDS FROM THE AFRICAN COAST NEAR 12N16W TO
A 1011 MB SURFACE LOW CENTERED NEAR 10N35W TO 08N41W. THE
INTERTROPICAL CONVERGENCE ZONE AXIS EXTENDS FROM 08N41W TO
06N57W. SCATTERED MODERATE CONVECTION IS OBSERVED SURROUNDING
THE LOW FROM 03N-13N BETWEEN 25W-43W.

...DISCUSSION...

GULF OF MEXICO...

A BROAD SURFACE RIDGE COVERING A GREAT PORTION OF THE ATLANTIC
BASIN EXTENDS W REACHING THE GULF WATERS AND ANCHORED BY A 1017
MB HIGH NEAR 26N87W. ALOFT...AN UPPER-LEVEL LOW IS OBSERVED
CENTERED OVER SOUTHERN MEXICO AND EXTENDING EASTWARD ACROSS THE
BAY OF CAMPECHE BRINGING MOISTURE FROM THE CARIBBEAN AND EPAC
INTO THE W GULF. AN UPPER-LEVEL HIGH IS CENTERED NEAR 30N89W AND
EXTENDING ACROSS THE CENTRAL AND E GULF. A DIFFLUENT FLOW
PREVAILS ACROSS THE E PORTION OF THE BASIN AND THE FLORIDA
PENINSULA SUPPORTING ISOLATED CONVECTION E OF 87W. SCATTEROMETER
DATA DEPICTS A LIGHT ANTICYCLONIC FLOW ACROSS MOST OF THE BASIN
EXCEPT N OF THE YUCATAN PENINSULA S OF 24N BETWEEN 88W-91W WHERE
LIGHT TO GENTLE FLOW IS OBSERVED. THE RIDGE IS FORECAST TO
REMAIN NEARLY STATIONARY THROUGH THE NEXT 24 HOURS.

CARIBBEAN SEA...

A TROPICAL WAVE IS MOVING ACROSS THE CENTRAL CARIBBEAN. PLEASE
REFER TO THE SECTION ABOVE FOR MORE DETAILS. AN AREA OF MODERATE
MOISTURE PREVAILS ACROSS THE NE AND CENTRAL CARIBBEAN N OF 14N
AND E OF 73W. THIS MOISTURE ALONG WITH AN UPPER-LEVEL LOW
CENTERED NE OF THE LEEWARD ISLANDS IS SUPPORTING ISOLATED
CONVECTION ACROSS PUERTO RICO...THE MONA PASSAGE...AND
HISPANIOLA. ANOTHER AREA OF MODERATE MOISTURE PREVAILS ACROSS
THE W CARIBBEAN W OF 75W AND WITH SUPPORT OF AN UPPER-LEVEL LOW
CENTERED OVER W CUBA...ISOLATED CONVECTION PREVAILS N OF 18N
BETWEEN 75W-79W. OVER THE SW CARIBBEAN...THE PROXIMITY OF THE
MONSOON TROUGH S OF PANAMA AND A SURFACE LOW OVER NE COLOMBIA
ARE PRODUCING SCATTERED MODERATE CONVECTION THAT IS MOVING OVER
THE SOUTHERN CARIBBEAN WATERS MAINLY S OF 11N. A STRONG DEEP
LAYER WIND SHEAR AND DRY AIR CONTINUES TO INHIBIT CONVECTION
ELSEWHERE. A GENERALLY TIGHT PRESSURE GRADIENT BETWEEN THE RIDGE
OVER THE ATLANTIC EXTENDING ACROSS THE NORTHERN BASIN AND LOWER
PRESSURES OVER COLOMBIA AND SOUTH AMERICA SUPPORTS GENTLE TO
MODERATE TRADES ACROSS MOST OF THE BASIN EXCEPT N OF 18N AND W
OF 73W WHERE A LIGHT EASTERLY FLOW PREVAILS. OVER THE NEXT 24
HOURS...EXPECT FOR THE TROPICAL WAVE TO CONTINUE MOVING W ACROSS
THE W CARIBBEAN INDUCING AN INCREASE IN MOISTURE. A SIMILAR
WEATHER PATTERN WILL PREVAIL ACROSS THE BASIN.

...HISPANIOLA...

THE MOISTURE ASSOCIATED WITH THE PASSAGE OF A TROPICAL WAVE WITH
AXIS S OF THE ISLAND NEAR 74W COMBINED WITH A MID-LEVEL
DIFFLUENT FLOW SUPPORTS ISOLATED MODERATE CONVECTION ACROSS THE
AREA. SIMILAR ACTIVITY IS POSSIBLE OVER THE NEXT 24 HOURS.

ATLANTIC OCEAN...

AN UPPER-LEVEL TROUGH PREVAILS OVER THE W ATLANTIC WITH BASE N
OF OUR AREA AND SUPPORTING A STATIONARY FRONT THAT IS CURRENTLY
GENERATING SCATTERED MODERATE CONVECTION N OF 29N AND W OF 78W.
A BROAD UPPER-LEVEL LOW CENTERED OVER W CUBA EXTENDS ACROSS THE
BAHAMAS SUPPORTING ISOLATED CONVECTION S OF 24N AND W OF 76W.
THE CENTRAL AND E ATLANTIC IS UNDER THE INFLUENCE OF A SURFACE
RIDGE ANCHORED BY A 1023 MB HIGH CENTERED NEAR 32N55W AND A 1022
MB HIGH CENTERED NEAR 33N28W. A WEAKNESS BETWEEN THESE TWO HIGHS
IS ANALYZED AS A SURFACE TROUGH FROM 26N51W TO 31N45W. OVER THE
NEXT 24 HOURS...EXPECT FOR THE SURFACE RIDGE TO PREVAIL ACROSS
THE BASIN WITH FAIR WEATHER.

FOR ADDITIONAL INFORMATION PLEASE VISIT
HTTP://WWW.HURRICANES.GOV/MARINE

$$

ERA
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