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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

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