[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 181040
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
805 AM EDT THU JUN 18 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 STRONG PRESSURE GRADIENT EXISTS BETWEEN A 1019 MB HIGH
CENTERED NORTHEAST OF THE BAHAMAS NEAR 28N75W AND LOWER PRESSURE
ACROSS NORTHERN COLOMBIA THAT IS RESULTING IN GALE FORCE E-NE
WINDS THIS MORNING WITHIN CLOSE PROXIMITY TO THE COAST OF
COLOMBIA. THIS WIND FIELD IS FORECAST TO PERSIST THROUGH EARLY
FRIDAY. SEE LATEST NWS HIGH SEAS FORECAST UNDER AWIPS/WMO
HEADERS MIAHSFAT2/FZNT02 KNHC FOR MORE DETAILS.

...TROPICAL WAVES...
TROPICAL WAVE EXTENDS FROM 05N36W TO 15N32W MOVING W AT 15-20
KT. THE WAVE COINCIDES WITH HIGHER MOISTURE VALUES ON TOTAL
PRECIPITABLE WATER IMAGERY BETWEEN 24W-34W. SCATTERED MODERATE
CONVECTION IS FROM 06N-09N BETWEEN 34W-39W.

TROPICAL WAVE EXTENDS FROM 04N68W TO 15N67W MOVING W AT 15-20
KT. THE WAVE COINCIDES WITH WEAK 700 MB TROUGHING BETWEEN 65W-
71W EMBEDDED WITHIN A LENGTHY EASTERLY JET STRETCHING FROM
12N37W TO 15N78W. NO SIGNIFICANT DEEP CONVECTION IS ASSOCIATED
WITH THE WAVE AT THIS TIME.

TROPICAL WAVE EXTENDS FROM 08N79N TO 16N80W MOVING W AT 15-20
KT. THE TOTAL PRECIPITABLE WATER IMAGERY SHOWS THE WAVE EMBEDDED
WITHIN INCREASED VALUES OF DEEP MOISTURE ACROSS THE WESTERN
CARIBBEAN SEA. ISOLATED MODERATE CONVECTION IS FROM 09N-11N
BETWEEN 78W-82W.

...ITCZ/MONSOON TROUGH...
THE MONSOON TROUGH EXTENDS FROM THE AFRICAN COAST NEAR 11N15W TO
09N25W. THE INTERTROPICAL CONVERGENCE ZONE AXIS EXTENDS FROM
09N25W TO 07N35W TO 05N52W. SCATTERED MODERATE CONVECTION IS
FROM 07N-10N BETWEEN 14W-18W. ISOLATED MODERATE CONVECTION IS
FROM 05N-10N BETWEEN 19W-31W.

...DISCUSSION...

GULF OF MEXICO...
AN UPPER LEVEL LOW IS CENTERED OVER THE NORTHEASTERN YUCATAN
PENINSULA NEAR 21N87W THAT IS PROVIDING MUCH OF THE GULF WITH
EAST-NORTHEASTERLY FLOW ALOFT WHICH ON WATER VAPOR IMAGERY
REMAINS RELATIVELY DRY AND STABLE ALOFT. AT THE SURFACE...
STABILITY PREVAILS AS WELL DUE TO SURFACE RIDGING ANCHORED BY A
1020 MB HIGH CENTERED IN THE NE GULF NEAR 29N87W. ONLY IN THE
FAR NW PORTION OF THE BASIN ARE A FEW SCATTERED SHOWERS AND
ISOLATED TSTMS OCCURRING N OF 25N W OF 93W. THIS ACTIVITY LIES
WITHIN AN AREA OF MODERATE TO FRESH SOUTHERLY FLOW ACROSS THE
WESTERN GULF...WHILE CLOSER TO THE HIGH CENTER GENTLE TO
OCCASIONAL MODERATE SE WINDS PREVAIL. THE SURFACE RIDGE AXIS IS
FORECAST TO REMAIN ALONG 28N FROM THE FLORIDA PENINSULA TO THE
SE TEXAS COAST THROUGH FRIDAY AND SHIFT SLIGHTLY NORTH TO 29N/
30N BY SATURDAY.

CARIBBEAN SEA...
WITH AN UPPER LEVEL LOW CENTERED OVER THE NORTHERN YUCATAN
PENINSULA NEAR 21N87W...MUCH OF THE CARIBBEAN IS UNDER THE
INFLUENCE OF WEST-SOUTHWESTERLY FLOW STEMMING FROM THE LOW.
MIDDLE TO UPPER LEVEL MOISTURE REMAINS ENHANCED NEAREST TO THE
UPPER LEVEL FEATURE WITH POSSIBLE ISOLATED SHOWERS OCCURRING W
OF 78W THIS MORNING. LATE EVENING SHOWERS AND TSTM ACTIVITY HAS
DIMINISHED ACROSS PORTIONS OF CUBA WITH ONLY A FEW ISOLATED
LINGERING ISOLATED SHOWERS ACROSS HISPANIOLA. OTHERWISE...A PAIR
OF TROPICAL WAVES ARE MOVING ACROSS THE SOUTHERN HALF OF THE
BASIN...EACH INFLUENCED BY A DRY SAHARAN AIR LAYER ALOFT
PROVIDING FOR OVERALL STABLE CONDITIONS AT THIS TIME. THE
PRIMARY IMPACT WILL REMAIN THE STRONG TO NEAR GALE TRADES
GENERALLY S OF 18N BETWEEN 65W-83W...INCLUDING THE GALE FORCE
WINDS MENTIONED IN THE SPECIAL FEATURES ABOVE. GIVEN THE
INCREASED PRESSURE GRADIENT ACROSS THE REGION...THESE TRADES ARE
EXPECTED TO PERSIST THROUGH THE UPCOMING WEEKEND INTO EARLY NEXT
WEEK.

...HISPANIOLA...
CURRENTLY...A FEW LINGERING ISOLATED SHOWERS AND TSTMS REMAIN
ACROSS THE ISLAND AND THIS ACTIVITY IS EXPECTED TO CONTINUE
DIMINISHING THROUGH THE EARLY MORNING HOURS. OTHERWISE...
WESTERLY FLOW ALOFT PREVAILS AND THIS WILL LIKELY PROVIDE AMPLE
MIDDLE TO UPPER LEVEL DYNAMICS FOR LATE AFTERNOON AND EARLY
EVENING SCATTERED SHOWERS AND TSTMS DUE TO DIFFLUENCE ALOFT AND
PEAK DAYTIME HEATING AND INSTABILITY IN THE LOWER LEVELS.

ATLANTIC OCEAN...
A 1020 MB HIGH IS CENTERED NORTHEAST OF THE BAHAMAS NEAR 28N75W.
FAIR SKIES ARE NOTED ACROSS MUCH OF THE SW NORTH ATLC THIS
MORNING. TO THE EAST OF THIS HIGH CENTER...AN UPPER LEVEL LOW IS
NOTED ON WATER VAPOR IMAGERY CENTERED NEAR 26N59W. MID-LEVEL
MOISTURE AND CLOUDINESS INCREASES IN THE VICINITY OF THIS
FEATURE BETWEEN 57W-69W WITH ISOLATED SHOWERS POSSIBLE. THE
REMAINDER OF THE CENTRAL AND EASTERN ATLC FALL UNDER THE
INFLUENCE OF SURFACE HIGH PRESSURE AND RIDGING WITH OVERALL FAIR
CONDITIONS PREVAILING.

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

$$
HUFFMAN
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