Tropical Weather Discussion
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000
AXNT20 KNHC 231743
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT THU JUL 23 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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1715 UTC.

...TROPICAL WAVES...
TROPICAL WAVE EXTENDS FROM 08N35W TO 17N34W MOVING W AT 15-20
KT. THE WAVE COINCIDES WITH BROAD 700 MB TROUGHING BETWEEN 30W-
38W WITH A MAXIMUM OF 850 MB RELATIVE VORTICITY ALONG THE WAVE
AXIS NEAR 11N. NO SIGNIFICANT CONVECTION IS OCCURRING IN
ASSOCIATION WITH THE WAVE AT THIS TIME DUE TO A STRONG SAHARAN
AIR LAYER PROVIDING OVERALL STABLE CONDITIONS OVER THE TROPICAL
EASTERN ATLC.

TROPICAL WAVE EXTENDS FROM 07N72W TO 18N70W MOVING W AT 15-20
KT. THE WAVE REMAINS EMBEDDED WITHIN A MAXIMUM OF TOTAL
PRECIPITABLE WATER BETWEEN 67W-75W OVER THE CENTRAL CARIBBEAN
SEA. ISOLATED MODERATE CONVECTION IS FROM 07N-11N BETWEEN 69W-
73W.

TROPICAL WAVE EXTENDS FROM 07N85W TO 16N83W MOVING W AT 20 KT.
THE WAVE COINCIDES WITH BROAD AND SUBTLE 700 MB TROUGHING OVER
THE WESTERN CARIBBEAN SEA AND CENTRAL AMERICA BETWEEN 76W-85W.
MOST MOISTURE ASSOCIATED WITH THE WAVE IS NOTED ACROSS CENTRAL
AMERICA WITH SCATTERED MODERATE CONVECTION OCCURRING FROM 08N-
14N BETWEEN 81W-87W.

...ITCZ/MONSOON TROUGH...
THE MONSOON TROUGH AXIS EXTENDS FROM THE AFRICAN COAST NEAR
12N17W TO 10N20W TO 08N34W. THE INTERTROPICAL CONVERGENCE ZONE
AXIS EXTENDS FROM 08N34W TO 07N46W TO 05N53W. ISOLATED MODERATE
CONVECTION IS FROM 07N-12N BETWEEN 13W-18W...AND FROM 05N-09N
BETWEEN 41W-53W. SCATTERED MODERATE CONVECTION IS FROM 06N-10N
BETWEEN 20W-38W.

...DISCUSSION...

GULF OF MEXICO...
A BROAD UPPER LEVEL LOW CENTERED NEAR 23N91W INFLUENCES MUCH OF
THE GULF BASIN...HOWEVER EXAMINING WATER VAPOR IMAGERY REMAINS
RELATIVELY DRY WITH THE EXCEPTION OF THE SOUTHERN PERIPHERY S OF
22N WHERE A FEW ISOLATED SHOWERS AND TSTMS ARE OCCURRING IN THE
VICINITY OF 21N96W. OTHERWISE...A SURFACE RIDGE PREVAILS
ANCHORED BY A 1018 MB HIGH CENTERED NEAR 25N84W. THE SURFACE
FEATURE ALONG WITH THE LACK OF MIDDLE TO UPPER LEVEL MOISTURE IS
PROMOTING GENERALLY CLEAR SKIES AND FAIR CONDITIONS THIS
AFTERNOON. WEAK FRONTAL TROUGHING IS ANALYZED OFF THE EASTERN
FLORIDA PENINSULA IN THE SW NORTH ATLC ALONG WITH A COLD FRONT
OFF THE COAST OF THE CAROLINAS TO THE NORTH. THE WEAK SURFACE
TROUGHING EXTENDS ACROSS NORTHERN FLORIDA AND THE NEAR SHORE NE
GULF WATERS N OF 29N E OF 90W WHERE A FEW ISOLATED SHOWERS AND
TSTMS ARE OCCURRING. GENTLE TO MODERATE ANTICYCLONIC WINDS ARE
FORECAST TO PERSIST THROUGH SUNDAY.

CARIBBEAN SEA...
A VERY BROAD CUTOFF UPPER LEVEL LOW IS CENTERED OVER HISPANIOLA
THAT INFLUENCES THE WESTERN CARIBBEAN W OF 75W WITH RELATIVELY
DRY AIR ALOFT AND OVERALL STABLE CONDITIONS THIS AFTERNOON. MOST
MOISTURE W OF 75W IS NOTED S OF 12N WITHIN AN AREA OF MAXIMUM
MIDDLE TO UPPER LEVEL DIFFLUENCE ALONG WITH A TROPICAL WAVE
ALONG 86W MOVING ACROSS CENTRAL AMERICA. SCATTERED SHOWERS AND
TSTMS ARE OCCURRING S OF 14N BETWEEN 75W-87W...INCLUDING
PORTIONS OF PANAMA...COSTA RICA...AND NICARAGUA. OTHERWISE...E
OF 75W...MIDDLE TO UPPER LEVEL MOISTURE INCREASES DUE TO
SOUTHWESTERLY FLOW ALOFT AND THE PRESENCE OF A TROPICAL WAVE
ALONG 71W PRIMARILY REMAINING S OF HISPANIOLA. LOW-LEVEL
MOISTURE REMAINS SCARCE IN THE VICINITY OF THE WAVE AXIS AND
ACROSS THE REMAINDER OF THE CENTRAL AND EASTERN CARIBBEAN WITH
MOSTLY CLEAR SKIES. CONVECTION ASSOCIATED WITH THE WAVE IS
IMPACTING INLAND PORTIONS OF NW VENEZUELA AND NORTHERN COLOMBIA.
LASTLY...MODERATE TO FRESH TRADES PREVAIL OUTSIDE OF THE CENTRAL
CARIBBEAN AND COLOMBIA COAST REGION WHERE SLIGHTLY STRONGER E-NE
WINDS ARE OCCURRING IN THE FRESH TO STRONG BREEZE RANGE.

...HISPANIOLA...
CURRENTLY...SKIES REMAIN MOSTLY CLEAR WITH A LACK OF ANY
SIGNIFICANT CONVECTION AT THIS TIME IN THE REGION. A TROPICAL
WAVE ALONG 71W CONTINUES PASSING TO THE SOUTH OF THE
ISLAND...HOWEVER IS NOT A MAJOR PRECIPITATION PRODUCER AT THIS
TIME DUE TO THE SAHARAN AIR LAYER PROVIDING A STABLE
ENVIRONMENT. DRY CONDITIONS ARE EXPECTED TO PERSIST THROUGH THE
EVENING AND OVERNIGHT HOURS INTO FRIDAY.

ATLANTIC OCEAN...
A LONGWAVE MIDDLE TO UPPER LEVEL TROUGH IS EVIDENT ON WATER
VAPOR IMAGERY OVER THE WESTERN NORTH ATLC THAT SUPPORTS A COLD
FRONT EXTENDING FROM 36N60W TO 32N73W TO THE NORTH CAROLINA
COAST NEAR 34N78W. SCATTERED SHOWERS AND ISOLATED TSTMS ARE
OCCURRING WITHIN 150 NM SE OF THE FRONT E OF 72W AND WITHIN 90
NM S OF THE FRONT W OF 72W. A PRE-FRONTAL SURFACE TROUGH IS
ANALYZED FROM 30N77W TO 26N80W AND IS PROVIDING FOCUS FOR
ISOLATED SHOWERS AND TSTMS WITHIN 120 NM E OF THE BOUNDARY.
FARTHER EAST...A SURFACE RIDGE ANCHORED BY A 1023 MB HIGH
CENTERED NEAR 27N53W INFLUENCES THE REMAINDER OF THE SW NORTH
ATLC. IN BETWEEN THIS RIDGE AND ANOTHER RIDGE TO THE EAST...A
SURFACE TROUGH EXTENDS FROM 20N46W TO 29N45W. THE SURFACE TROUGH
COINCIDES WITH AN UPPER LEVEL LOW CENTERED NEAR 26N47W THAT
CONTINUES TO RETROGRADE AND GENERATE POSSIBLE ISOLATED SHOWERS
FROM 24N-30N BETWEEN 44W-49W. LASTLY...THE EASTERN ATLC IS
INFLUENCED BY A SURFACE RIDGE ANCHORED ON A 1026 MB HIGH
CENTERED NEAR 33N33W.

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

$$
HUFFMAN


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