Tropical Weather Discussion
Issued by NWS

Current Version | Previous Version | Text Only | Print | Product List | Glossary Off
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50

000
AXNT20 KNHC 281049
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
805 AM EDT TUE JUL 28 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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1015 UTC.

...SPECIAL FEATURES...
A STRENGTHENED PRESSURE GRADIENT IS NOTED ACROSS THE CENTRAL
CARIBBEAN SEA WITH NEAR GALE TO GALE FORCE WINDS OCCURRING FROM
11N-14N BETWEEN 72W-77W. THESE CONDITIONS ARE FORECAST TO
DIMINISH BELOW GALE FORCE WARNING CRITERIA BY 28/1200 UTC. SEE
LATEST NWS HIGH SEAS FORECAST UNDER AWIPS/WMO HEADERS
MIAHSFAT2/FZNT02 KNHC FOR MORE DETAILS.

...TROPICAL WAVES...
TROPICAL WAVE EXTENDS FROM 12N29W TO 19N27W MOVING W AT 15 KT.
THE WAVE COINCIDES WITH BROAD AND VERY SUBTLE 700 MB TROUGHING
BETWEEN 26W-32W WITH 850 MB RELATIVE VORTICITY FOCUSED NEAR THE
SOUTHERN EXTENT OF THE WAVE AXIS. ISOLATED MODERATE CONVECTION
IS FROM 11N-13N BETWEEN 22W-27W.

TROPICAL WAVE EXTENDS FROM 08N47W TO 17N45W MOVING W AT 15 KT.
THE WAVE COINCIDES WITH BROAD 700 MB TROUGHING BETWEEN 45W-53W.
NO SIGNIFICANT CONVECTION IS OCCURRING WITH THE WAVE AT THIS
TIME.

TROPICAL WAVE EXTENDS FROM 08N72W TO 18N69W MOVING W AT 15 KT.
THE WAVE COINCIDES WITH 700 MB TROUGHING BETWEEN 68W-75W WITH NO
SIGNIFICANT CONVECTION OCCURRING AT THIS TIME.

TROPICAL WAVE EXTENDS FROM 10N85W TO 19N84W MOVING W AT 15-20
KT. THE WAVE COINCIDES WITH BROAD 700 MB TROUGHING BETWEEN 82W-
89W. ISOLATED MODERATE CONVECTION IS FROM 12N-17N BETWEEN 84W-
87W.

...ITCZ/MONSOON TROUGH...
THE MONSOON TROUGH AXIS EXTENDS FROM THE AFRICAN COAST NEAR
14N17W TO 12N24W TO 11N31W TO 10N37W TO 11N44W. THE
INTERTROPICAL CONVERGENCE ZONE AXIS EXTENDS FROM 08N48W TO
05N53W. SCATTERED MODERATE CONVECTION IS FROM 07N-13N BETWEEN
15W-23W.

...DISCUSSION...

GULF OF MEXICO...
NORTHEAST TO EASTERLY FLOW ALOFT INFLUENCES THE GULF BASIN THIS
MORNING ON THE SOUTHERN PERIPHERY OF A BROAD UPPER LEVEL
ANTICYCLONIC CIRCULATION ANCHORED OVER THE LOWER MISSISSIPPI
RIVER VALLEY REGION. WHILE PROVIDING A GENERALLY STABLE
ENVIRONMENT ALOFT...A SURFACE WEAKNESS IN THE FORM OF A 1013 MB
LOW CENTERED IN THE NE GULF NEAR 29N83W AND SURFACE TROUGHING
EXTENDING SW FROM THE LOW TO 27N86W IS PROVIDING FOCUS FOR
SCATTERED SHOWERS AND TSTMS. THIS ACTIVITY IS OCCURRING FROM 26N-
29N BETWEEN 83W-87W WITH MID-LEVEL ENERGY NOTED OVER THE EASTERN
GULF CONTINUING TO PROVIDE MARGINAL LIFTING DYNAMICS FOR THE
CONVECTION. OTHERWISE...A WEAK SURFACE RIDGE ANCHORED BY A 1017
MB HIGH CENTERED NEAR 23N84W WILL MAINTAIN GENTLE TO MODERATE
ANTICYCLONIC WINDS THROUGH LATE WEDNESDAY AS THE HIGH DRIFTS
GRADUALLY NORTHWESTWARD.

CARIBBEAN SEA...
WATER VAPOR IMAGERY INDICATES MOSTLY DRY CONDITIONS ALOFT OVER
MUCH OF THE CARIBBEAN BASIN THIS MORNING WHICH IS LIMITING ANY
WIDESPREAD AREAS OF STRONG AND DEEP CONVECTION. HOWEVER THE
PRESENCE OF A TROPICAL WAVE ALONG 85W IS GENERATING A FEW
ISOLATED SHOWERS AND TSTMS FROM 12N-17N BETWEEN 84W-87W AND
ACROSS PORTIONS OF HONDURAS AND NICARAGUA. OTHERWISE...THE
PRIMARY MARINE IMPACT IS INCREASED TRADES ACROSS CENTRAL
PORTIONS REACHING NEAR GALE TO GALE FORCE IN CLOSE PROXIMITY TO
THE COAST OF COLOMBIA. WHILE THE GALE IS FORECAST THROUGH
28/1200 UTC...THE AREA OF TRADES IS EXPECTED TO PERSIST IN THE
STRONG BREEZE TO NEAR GALE RANGE THROUGH THURSDAY.

...HISPANIOLA...
CURRENTLY...MOSTLY CLEAR SKIES AND FAIR CONDITIONS PREVAIL
ACROSS THE ISLAND FOR THE MORNING HOURS. GIVEN DRY AND STABLE
AIR ALOFT ALONG WITH RELATIVELY CLEAR SKIES NOTED ON SATELLITE
IMAGERY TO THE EAST...NO SIGNIFICANT DEEP CONVECTION IS EXPECTED
ACROSS THE ISLAND THROUGH TUESDAY INTO WEDNESDAY.

ATLANTIC OCEAN...
WATER VAPOR IMAGERY INDICATED LONGWAVE TROUGHING OVER THE
WESTERN NORTH ATLC WITH A FEW EMBEDDED SHORTWAVES NEAR THE BASE
OF THE TROUGHING SLIGHTLY NORTH OF THE DISCUSSION BORDER...ONE
NEAR 37N51W AND THE OTHER NEAR 37N66W. BOTH SUPPORT WEAK SURFACE
LOWS AND FRONTS. THE FIRST LOW IS A 1013 MB LOW CENTERED NEAR
37N47W WITH A COLD FRONT EXTENDING SW TO 30N52W TO 29N57W THEN
STATIONARY TO 32N60W. THE FRONT CONTINUES AS A WARM FRONT FROM
THERE INTO A 1010 MB LOW CENTERED NORTH OF BERMUDA NEAR 35N65W.
THE ASSOCIATED COLD FRONT EXTENDS W-SW FROM THE 1010 MB LOW TO
33N72W AND BECOMES STATIONARY TO 31N80W. ISOLATED SHOWERS ARE
OCCURRING WITHIN 90 NM EAST OF THE FIRST COLD FRONT MENTIONED...
HOWEVER IS RELATIVELY DRIER THAN THE DEEPER SURFACE LOW TO THE
WEST. GIVEN THE STRONGER MIDDLE TO UPPER LEVEL DYNAMICS WITH THE
WESTERN-MOST LOW PRESSURE AREA...SCATTERED SHOWERS AND TSTMS ARE
OCCURRING GENERALLY N OF 28N BETWEEN 65W-79W. OTHERWISE...THE
REMAINDER OF THE SW NORTH ATLC IS UNDER THE INFLUENCE OF A
SURFACE RIDGE ANCHORED BY A 1020 MB HIGH CENTERED NEAR 27N63W
WITH AXIS EXTENDING FROM THE HIGH CENTER TO A 1017 MB HIGH
CENTERED IN THE SE GULF OF MEXICO NEAR 24N84W. FINALLY...THE
REMAINDER OF THE CENTRAL AND EASTERN ATLC IS UNDER THE INFLUENCE
OF ANOTHER SURFACE RIDGE ANCHORED BY A 1026 MB HIGH CENTERED
S-SE OF THE AZORES NEAR 35N29W.

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

$$
HUFFMAN



USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.