[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 161748
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT THU JUL 16 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 05N41W TO 15N36W MOVING W AT 20-25
KT. THE WAVE COINCIDES WITH A GLOBAL MODEL INDICATED 700 MB
SHORTWAVE TROUGH EMBEDDED SLIGHTLY WITHIN THE MONSOON TROUGH
ALONG 10N. TO THE N-NW OF THE DEPICTED WAVE AXIS...A BROADER 700
MB TROUGH IS NOTED BETWEEN 40W-50W. MAXIMUM LOW-LEVEL...850
MB...RELATIVE VORTICITY FIELDS ARE INDICATED ALONG THE WAVE AXIS
NEAR 10N. SCATTERED MODERATE CONVECTION IS FROM 06N-12N BETWEEN
32W-42W.

TROPICAL WAVE EXTENDS FROM 06N69W TO 17N67W MOVING W AT 20 KT.
THE WAVE COINCIDES WITH BROAD GLOBAL MODEL INDICATED 700 MB
TROUGHING ACROSS THE EASTERN CARIBBEAN SEA WITH MOST RELATIVE
VORTICITY AT 850 MB REMAINING S OF 12N OVER PORTIONS OF NW
VENEZUELA. ISOLATED MODERATE CONVECTION IS ACROSS CENTRAL
VENEZUELA WITH ISOLATED SHOWERS OCCURRING ACROSS THE CARIBBEAN
WATERS FROM 12N-18N BETWEEN 60W-71W.

TROPICAL WAVE EXTENDS FROM 04N84W TO 15N84W MOVING W AT 15 KT.
WHILE MOST OF THE ENERGY ASSOCIATED WITH THE WAVE CONTINUES TO
MOVE INTO THE EASTERN PACIFIC REGION...SUBTLE LOW-LEVEL
TROUGHING IS NOTED OVER CENTRAL AMERICA IN THE VICINITY OF THE
WAVE. THESE DYNAMICS ARE PROVIDING FOR ISOLATED MODERATE
CONVECTION FROM 11N-17N BETWEEN 81W-87W. THIS CONVECTION REMAINS
ENHANCED DUE TO UPPER LEVEL DIFFLUENCE ON THE WESTERN PERIPHERY
OF AN UPPER LEVEL RIDGE CENTERED OVER THE SW CARIBBEAN SEA.

...ITCZ/MONSOON TROUGH...
THE MONSOON TROUGH EXTENDS FROM THE AFRICAN COAST NEAR 12N16W TO
10N35W TO 09N39W. THE INTERTROPICAL CONVERGENCE ZONE AXIS
EXTENDS FROM 08N41W TO 06N48W TO 07N58W. ASIDE FROM CONVECTION
ASSOCIATED WITH THE TROPICAL WAVE ALONG 39W...WIDELY SCATTERED
MODERATE CONVECTION IS FROM 05N-09N BETWEEN 11W-24W.

...DISCUSSION...

GULF OF MEXICO...
UPPER LEVEL NORTHEAST TO EASTERLY FLOW IS OCCURRING OVER MUCH OF
THE GULF BETWEEN A MIDDLE TO UPPER LEVEL RIDGE ANCHORED OVER
NORTH TEXAS NEAR 31N97W AND A MIDDLE TO UPPER LEVEL LOW CENTERED
OVER SOUTHERN MEXICO NEAR 18N97W. DEBRIS MOISTURE AND CLOUDINESS
CONTINUES TO SPREAD SOUTHWESTWARD FROM ACTIVE CONVECTION
OCCURRING ACROSS THE NE GULF. A WEAKNESS WITHIN THE SURFACE
RIDGE...AND ASSOCIATED FRONTAL TROUGHING SAGGING SOUTHWARD
ACROSS THE SE CONUS IS GENERATING SCATTERED SHOWERS AND TSTMS
FROM 26N-30N BETWEEN 82W-88W. OTHERWISE...THE REMAINDER OF THE
BASIN IS UNDER THE INFLUENCE OF SURFACE RIDGING ANCHORED BY A
1017 MB HIGH CENTERED ALONG THE LOUISIANA COAST NEAR 29N91W AND
A RIDGE AXIS EXTENDING FROM THE SW NORTH ATLC ALONG 24N.
PRIMARILY LIGHT TO GENTLE ANTICYCLONIC WINDS PREVAIL IN THE
VICINITY OF THE RIDGING WITH GENTLE TO OCCASIONAL MODERATE SE
WINDS OCCURRING ACROSS PORTIONS OF THE WESTERN GULF. THE RIDGE
IS FORECAST TO REMAIN NEARLY STATIONARY THROUGH SATURDAY.

CARIBBEAN SEA...
GENERALLY NORTHWESTERLY FLOW ALOFT IS NOTED ON WATER VAPOR
IMAGERY W OF 64W BETWEEN AN UPPER LEVEL RIDGE CENTERED OVER THE
SW CARIBBEAN NEAR 11N78W AND A BROAD MIDDLE TO UPPER LEVEL LOW
CENTERED NE OF THE LEEWARD ISLANDS NEAR 18N60W. THE NW FLOW IS
NOT ONLY PROVIDING STABILITY WITH RELATIVELY DRY AIR ALOFT...BUT
IT PROVIDING AMPLE DEEP LAYER WIND SHEAR TO INHIBIT ANY
SIGNIFICANT DEEP CONVECTION THIS AFTERNOON. A TROPICAL WAVE IS
ALONG 68W MOVING WEST...AND IS GENERATING ISOLATED SHOWERS AND
TSTMS FROM 13N-18N BETWEEN 60W-71W. FARTHER WEST...ANOTHER
TROPICAL WAVE ALONG 84W IS ENTERING INTO THE EAST PACIFIC
REGION...YET CONTINUES TO MOVE ACROSS PORTIONS OF COSTA RICA AND
NICARAGUA PRODUCING SCATTERED SHOWERS AND TSTMS FROM 09N-18N
BETWEEN 81W-90W...WITH THE NORTHERN EXTENT OF THIS CONVECTION
LARGELY INFLUENCED BY MIDDLE TO UPPER LEVEL DIFFLUENCE ON THE
WESTERN PERIPHERY OF THE RIDGE CENTERED OVER THE SW CARIBBEAN.
FINALLY...TRADES REMAIN ENHANCED ACROSS CENTRAL PORTIONS DUE TO
A STRENGTHEN PRESSURE GRADIENT. FRESH TO OCCASIONAL STRONG E-NE
WINDS ARE EXPECTED TO PERSIST THROUGH THE UPCOMING WEEKEND.

...HISPANIOLA...
CURRENTLY...FAIR WEATHER CONDITIONS PREVAIL ACROSS THE ISLAND.
THE APPROACH OF A TROPICAL WAVE SE OF THE ISLAND ALONG 68W IS
INCREASING CLOUDINESS AND WIDELY SCATTERED SHOWERS AND ISOLATED
TSTMS IN THE ADJACENT SOUTHERN COASTAL WATERS. GIVEN PEAK
DAYTIME HEATING AND INSTABILITY...ISOLATED SHOWERS AND TSTMS ARE
EXPECTED THROUGH THE LATE AFTERNOON AND EARLY EVENING HOURS
ACROSS THE ISLAND...WITH ACTIVITY DIMINISHING THROUGH THE
OVERNIGHT HOURS INTO EARLY FRIDAY.

ATLANTIC OCEAN...
AN UPPER LEVEL TROUGH HAS MOVED EAST OF THE DELMARVA REGION WITH
THE AXIS NOW EXTENDING FROM 38N74W TO 29N76W. THIS SHORTWAVE
TROUGHING SUPPORTS A 1008 MB LOW CENTERED NEAR 38N68W WITH COLD
FRONT EXTENDING SW TO 33N75W BECOMING STATIONARY TO THE WEST TO
THE SOUTHERN SOUTH CAROLINA COAST NEAR 33N80W. TO THE SOUTH OF
THE FRONT...LOW-LEVEL MOISTURE CONVERGENCE COUPLED WITH MAXIMUM
MIDDLE TO UPPER LEVEL DIFFLUENCE IS GENERATING SCATTERED SHOWERS
AND ISOLATED TSTMS ACROSS MUCH OF THE SW NORTH ATLC FROM 21N-33N
BETWEEN 70W-80W. FARTHER EAST...THE REMAINDER OF THE CENTRAL AND
EASTERN ATLC IS UNDER THE INFLUENCE OF A SURFACE RIDGE ANCHORED
BY A 1025 MB HIGH CENTERED NEAR 30N58W AND A 1023 MB HIGH
CENTERED NEAR 31N35W. A WEAKNESS BETWEEN THESE TWO HIGHS IS
ANALYZED AS A SURFACE TROUGH FROM 32N44W TO 27N52W. POSSIBLE
ISOLATED SHOWERS ARE OCCURRING WITHIN 60 NM EITHER SIDE OF THE
BOUNDARY.

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

$$
HUFFMAN
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