[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 121750
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT SUN JUL 12 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 10N31W TO 20N30W MOVING W AT 10 TO 15
KT OVER THE PAST 24 HOURS. THE WAVE COINCIDES WITH BROAD MID
LEVEL TROUGHING NOTED BOTH ON SATELLITE IMAGERY AND IN THE 700
MB LEVELS ON THE GFS. THIS WAVE IS AT THE LEADING EDGE OF A
POLEWARD SURGE IN MID LEVEL MOISTURE TO 16N. HOWEVER...SAHARAN
DUST IS EVIDENT AS FAR S AS 15N ALONG THE WAVE AXIS. ISOLATED
MODERATE CONVECTION IS FROM 05N TO 12N BETWEEN 28W AND 34W.

TROPICAL WAVE EXTENDS FROM 09N52W TO 19N49W MOVING W AT AROUND
20 KT OVER THE PAST 24 HOURS. THE WAVE COINCIDES WITH A
RELATIVELY BROAD 700 MB GLOBAL MODEL INDICATED TROUGH BETWEEN
48W AND 57W. THIS WAVE IS EMBEDDED IN RELATIVELY DRY AIR WITH
SAHARAN DUST N OF 10N. HOWEVER...UPPER LEVEL DIFFLUENCE IS
SUPPORTING ISOLATED MODERATE CONVECTION FROM 16N TO 19N BETWEEN
49W AND 53W.

TROPICAL WAVE EXTENDS FROM 09N75W TO 19N74W MOVING W AT 15 TO 20
KT OVER THE PAST 24 HOURS. THE NORTHERN PORTION OF THIS WAVE IS
MOVING UNDER AN UPPER LEVEL LOW WITH STRONG WESTERLY SHEAR OVER
THE SOUTHERN PORTION OF THE WAVE. ALTHOUGH HIGH MOISTURE IS ALSO
OVER THE SOUTHERN PORTION OF THE WAVE...THE PRESENCE OF THE
SHEAR IS INHIBITING CONVECTION.

...ITCZ/MONSOON TROUGH...
THE MONSOON TROUGH EXTENDS FROM THE AFRICAN COAST NEAR 12N16W TO
10N30W...WHERE THE ITCZ BEGINS AND CONTINUES THROUGH 08N40W TO
THE S AMERICA COAST NEAR 06N58W. SCATTERED MODERATE CONVECTION IS
FROM 04N TO 10N BETWEEN 12W AND 28W. ISOLATED MODERATE
CONVECTION IS FROM 04N TO 11N BETWEEN 40W AND 57W.

...DISCUSSION...

GULF OF MEXICO...

MIDDLE TO UPPER LEVEL RIDGING CENTERED OVER TX CONTINUES TO
PRODUCE NW WINDS ALOFT ACROSS THE MAJORITY OF THE GULF EXCEPT FOR
THE SW BASIN. AT THE SURFACE...A CONVECTION FREE TROUGH IS OVER
THE SW GULF FROM 22N92W TO 18N94W AND IS A DIURNAL EFFECT OF THE
YUCATAN COAST PRODUCING WINDS TO 25 KT. A 1020 MB HIGH CENTERED
NEAR 28N92W SUPPORTS LIGHT TO MODERATE ANTICYCLONIC FLOW ACROSS
THE MAJORITY OF THE GULF BASIN. A SURFACE TROUGH EXTENDING FROM
31N83W TO 25N84W IS INTERACTING WITH A MOIST AIRMASS TO SUPPORT
CLUSTERS OF MODERATE TO STRONG CONVECTION FROM 25N TO 29N
BETWEEN 82W AND 88W...INCLUDING THE WEST-CENTRAL FL COAST. OVER
THE NEXT 24 HOURS CONVECTION WILL CONTINUE TO BE POSSIBLE OVER
THE EASTERN GULF IN THE VICINITY OF THE SURFACE TROUGH.

CARIBBEAN SEA...

AN UPPER LOW BETWEEN THE SE BAHAMAS AND CUBA IS PRODUCING
CYCLONIC FLOW OVER THE MAJORITY OF THE CARIBBEAN BASIN. A REGION
OF UPPER LEVEL DIFFLUENCE TO THE SOUTHEAST OF THE UPPER LOW IS
SUPPORTING CLUSTERS OF MODERATE CONVECTION FROM 15N TO 20N
BETWEEN 62W AND 70W...INCLUDING PUERTO RICO AND THE VIRGIN
ISLANDS. MODERATE MOISTURE IN THE CYCLONIC FLOW SUPPORTS
SCATTERED THUNDERSTORMS FROM 18N TO 22N BETWEEN 76W AND
88W...INCLUDING JAMAICA AND THE CAYMAN ISLANDS. UPPER LEVEL
DIFFLUENCE OVER THE SW CARIBBEAN SUPPORTS CLUSTERS OF MODERATE
TO STRONG CONVECTION S OF 13N W OF 79W. A TROPICAL WAVE IS OVER
THE CENTRAL CARIBBEAN. PLEASE SEE THE TROPICAL WAVES SECTION FOR
MORE DETAILS. TRADE WINDS ARE SLIGHTLY WEAKER TODAY THAN THE
PREVIOUS SEVERAL DAYS OVER THE CARIBBEAN DUE TO THE WEAKENING OF
SURFACE RIDGING OVER THE WESTERN ATLC. MODERATE TO FRESH TRADES
COVER THE WESTERN AND EASTERN THIRDS OF THE BASIN...WITH FRESH
TO STRONG TRADE WINDS OVER THE CENTRAL THIRD OF THE CARIBBEAN.
THE UPPER LOW WILL LIFT NORTH AND WEST OVER THE NEXT 24 HOURS
WHICH WILL TAKE THE FAVORABLE UPPER LEVEL DIFFLUENCE OUT OF THE
BASIN...DECREASING CONVECTION OVER PUERTO RICO AND THE VIRGIN
ISLANDS HEADING INTO MONDAY. A WESTWARD MOVING TROPICAL WAVE
WILL HELP TO ENHANCE CONVECTION OVER THE WESTERN CARIBBEAN ON
MONDAY.

...HISPANIOLA...
A BROAD UPPER LOW CENTERED A COUPLE HUNDRED MILES NW OF THE
ISLAND IS SUPPORTING UPPER LEVEL DIFFLUENCE WITH NUMEROUS
SHOWERS MAINLY OVER THE EASTERN PORTION OF THE DOMINICAN
REPUBLIC TODAY. THESE SHOWERS ARE FORECAST TO PERSIST INTO THE
EVENING WHICH COULD RESULT IN HEAVY RAINFALL AND FLASH FLOODING
WITH THE POTENTIAL FOR MUDSLIDES. SCATTERED THUNDERSTORMS ARE
POSSIBLE OVER THE REMAINDER OF THE ISLAND THROUGH MONDAY. MODELS
ARE FORECASTING THE HIGHEST CHANCES FOR HEAVY PRECIPITATION TO
SHIFT NORTH OF THE ISLAND ON MONDAY.

ATLANTIC OCEAN...

A BROAD UPPER LOW IS CENTERED NEAR 22N74W AND SUPPORTS A LARGE
AREA OF UNSETTLED WEATHER WITH NUMEROUS SHOWERS AND SCATTERED
THUNDERSTORMS FROM 19N TO 26N BETWEEN 63W AND 77W. AN UPPER
LEVEL RIDGE CENTERED NEAR 31N71W IS PRODUCING UPPER LEVEL
DIFFLUENCE WHICH SUPPORTS WIDELY SCATTERED MODERATE CONVECTION
FROM 28N TO 31N BETWEEN 51W AND 66W. A BROAD SURFACE RIDGE AXIS
THROUGH A 1025 MB HIGH CENTERED NEAR 30N48W DOMINATES THE
CENTRAL AND EASTERN SUBTROPICAL ATLC EAST OF 50W. TWO TROPICAL
WAVES ARE OVER THE TROPICAL NORTHERN ATLC. PLEASE SEE THE
TROPICAL WAVES SECTION FOR MORE DETAILS. OVER THE NEXT 24 HOURS
EXPECT CONVECTION TO CONTINUE ACROSS THE SOUTHWESTERN NORTHERN
ATLC NEAR THE UPPER LOW.

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

$$
LATTO
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