[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 301745
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT SUN JUN 30 2013

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
1645 UTC.

...TROPICAL WAVES...
TROPICAL WAVE IS ALONG 19N35W TO 10N36W MOVING WEST AT 15 KT.
THE WAVE IS ILL-DEFINED AT THE SURFACE...BUT ALIGNS WELL WITH A
700 MB TROUGH AXIS. NO DEEP CONVECTION IS ASSOCIATED WITH THE
WAVE.

TROPICAL WAVE IS ALONG 21N64W TO 12N66W MOVING WEST AT 10 KT.
THE WAVE LIES WITHIN A LARGE SURGE OF DEEP LAYER MOISTURE
PRESENT IN TOTAL PRECIPITABLE WATER IMAGERY. SCATTERED MODERATE
CONVECTION IS FROM 12N-18N BETWEEN 59W-65W. ISOLATED MODERATE
CONVECTION IS FROM 19N-22N BETWEEN 58W-63W. THIS ACTIVITY IS
ALSO BEING ENHANCED BY DIFFLUENT FLOW ALOFT AROUND AN UPPER
LEVEL TROUGH OVER THE EASTERN CARIBBEAN.

TROPICAL WAVE IS MOVING SLOWLY THROUGH THE WESTERN CARIBBEAN
ALONG 20N84W TO 12N83W MOVING WEST AT 5-10 KT. THE WAVE LIES
WITHIN A BROAD AREA OF ENHANCED MOISTURE OVER MUCH OF THE
WESTERN CARIBBEAN. SCATTERED MODERATE/STRONG CONVECTION IS EAST
OF THE AXIS FROM 16N-20N BETWEEN 82W-84W. SIMILAR ACTIVITY IS
FROM 9N-15N BETWEEN 77W-80W. SCATTERED MODERATE CONVECTION IS
ALSO FROM 15N-23N BETWEEN 79W-83W. A SHORTWAVE UPPER TROUGH
EXTENDING FROM EASTERN CUBA TO NEAR 16N80W MAY BE ENHANCING SOME
OF THIS CONVECTION.

...ITCZ/MONSOON TROUGH...
THE MONSOON TROUGH EXTENDS FROM THE COAST OF MAURITANIA NEAR
19N16 TO 12N19W 10N23W. THE ITCZ BEGINS NEAR 10N23W AND
CONTINUES ALONG 8N33W 4N41W EQ52W. ISOLATED MODERATE CONVECTION
IS FROM 9N-13N BETWEEN 17W-23W. SIMILAR ACTIVITY IS WITHIN 140
NM SOUTH OF THE AXIS BETWEEN 25W-32W. SCATTERED MODERATE
CONVECTION IS WITHIN 160 NM SOUTH OF THE AXIS BETWEEN 35W-42W.

...DISCUSSION...

GULF OF MEXICO...
AN UPPER LEVEL TROUGH CONTINUES TO DIG SOUTHWARD INTO THE GULF
OF MEXICO WITH AXIS EXTENDING FROM EASTERN LOUISIANA NEAR 29N90W
TO THE SW GULF NEAR 20N93W. THE UPPER TROUGH SUPPORTS A FRONTAL
BOUNDARY THAT STILL BORDERS THE NW GULF COAST. A PRE-FRONTAL
SURFACE TROUGH IS OUT AHEAD OF THE FRONT ALONG 31N85W 28N90W
28N95W...AS OF 1500 UTC. RADAR IMAGERY AND LIGHTNING DATA
INDICATE SCATTERED SHOWERS/THUNDERSTORMS ARE THROUGHOUT THE NE
GULF NORTH OF 26N TO THE SURFACE TROUGH...EAST OF 94W. A FEW
ISOLATED SHOWERS/THUNDERSTORMS ARE ALSO IN THE SE GULF. ONLY THE
SW GULF REMAINS RELATIVELY CLEAR. MAINLY WEST TO SOUTHWEST WINDS
ARE IMPACTING THE GULF INCREASING FROM 5-10 KT IN THE SOUTHERN
GULF TO 15-20 KT NEAR THE SURFACE TROUGH. THE FRONTAL
BOUNDARY/SURFACE TROUGH WILL REMAIN ACROSS THE NORTHERN GULF
WITH MOIST CONDITIONS REMAINING OVER MUCH OF THE EASTERN GULF.

CARIBBEAN SEA...
A TROPICAL WAVE CONTINUES TO MOVE SLOWLY THROUGH THE WESTERN
CARIBBEAN ALONG 84W. IT IS HELPING ENHANCE SCATTERED
SHOWERS/THUNDERSTORMS OVER WESTERN CUBA AND UP TO 300 NM EAST OF
THE AXIS. SEE TROPICAL WAVE SECTION ABOVE FOR MORE DETAILS. AN
UPPER TROUGH EXTENDS FROM EASTERN CUBA TO NEAR 16N80W...WHICH IS
LIKELY ENHANCING SOME OF THE ACTIVITY NEAR THE WAVE. SOUTH OF
THE WAVE...THE MONSOON TROUGH EXTENDS FROM COSTA RICA TO
NORTHERN COLOMBIA. WEAK UPPER RIDGING COVERS THE CENTRAL
CARIBBEAN ALONG WITH DRY AIR ALOFT...WHICH IS KEEPING THIS
PORTION OF THE BASIN RATHER CLEAR. THE EASTERN CARIBBEAN IS
IMPACTED BY A SECOND TROPICAL WAVE NEAR 65W. CONVECTION NEAR THE
WAVE IS BEING SHEARED TO THE EAST DUE TO SOUTHWESTERLY FLOW
ALOFT AROUND AN UPPER TROUGH ALONG 68W. SCATTERED
SHOWERS/POSSIBLE THUNDERSTORMS ARE EAST OF THE WAVE THROUGH THE
LESSER ANTILLES. A FEW CLUSTERS OF SHOWERS/THUNDERSTORMS ARE
WEST OF THE WAVE OVER WESTERN PUERTO RICO...AND SOUTH OF THE
DOMINICAN REPUBLIC. EXCEPT FOR THE SLIGHT CYCLONIC FLOW NEAR THE
TWO WAVES...TRADEWIND FLOW OF 15-20 KT DOMINATES ELSEWHERE. BOTH
WAVES ARE EXPECTED TO MOVE WEST OVER THE NEXT SEVERAL DAYS.
WIDESPREAD MOISTURE WILL REMAIN OVER THE FAR WESTERN GULF AND
CENTRAL AMERICA.

HISPANIOLA...
HISPANIOLA IS FAIRLY DRY AT THIS TIME WITH NO NOTABLE SHOWERS OR
THUNDERSTORMS AT THIS TIME. AS HEATING CONTINUES THROUGHOUT THE
DAY SHOWER ACTIVITY WILL LIKELY INCREASE. MOISTURE AHEAD OF THE
TROPICAL WAVE IN THE EASTERN CARIBBEAN HAS ALSO ALMOST REACHED
THE INLAND...WHICH WILL INCREASE THE CHANCE OF RAIN.

ATLANTIC OCEAN...
BROAD SURFACE RIDGING COVERS THE WEST AND CENTRAL ATLC AROUND A
1031 MB HIGH NEAR 41N46W. SCATTERED SHOWERS/THUNDERSTORMS ARE
ACROSS MUCH OF THE NW BAHAMAS NORTH OF 26N BETWEEN 75W-80W
ASSOCIATED WITH MOIST AND DIFFLUENT FLOW ALOFT BETWEEN AN UPPER
TROUGH OVER THE GULF OF MEXICO AND AN UPPER LEVEL RIDGE TO THE
EAST NEAR 34N74W. A BROAD UPPER LOW IS CENTERED NEAR 26N63W. THE
UPPER LOW SUPPORTS A WEAK SURFACE TROUGH ALONG 37N55W TO 28N54W.
A FEW ISOLATED SHOWERS ARE WITHIN 75 NM EITHER SIDE OF THE AXIS.
A STRONGER UPPER LOW IS TO THE EAST NEAR 33N47W...BUT IS NOT
CAUSING ANY ACTIVE WEATHER. THE REMAINDER OF THE EASTERN ATLC IS
DOMINATED BY BROAD SURFACE RIDGING EXTENDING FROM A 1032 MB
AZORES HIGH. BROAD UPPER RIDGING SUPPORTS THE SURFACE RIDGE
EXTENDS FROM THE AZORES TO NEAR 19N32W 11N57W.

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

$$
WALTON


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