[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 010002
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
805 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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
2345 UTC.

...TROPICAL WAVES...
TROPICAL WAVE IS ALONG 20N37W TO 10N38W MOVING WEST AT 15 KT.
THE WAVE IS ILL-DEFINED AT THE SURFACE PER A 2022 UTC ASCAT
PASS. THE WAVE IS WELL DEFINED AT 700 MB AND IS ALIGNED WITH A
TROUGH AXIS AT THAT LEVEL. NO DEEP CONVECTION IS ASSOCIATED WITH
THE WAVE.

TROPICAL WAVE IS ALONG 21N65W TO 12N67W MOVING WEST AT 10 KT.
THE WAVE LIES WITHIN A SURGE OF DEEP LAYER MOISTURE PRESENT IN
TOTAL PRECIPITABLE WATER IMAGERY. SCATTERED MODERATE CONVECTION
REMAINS AT THE FAR NORTHERN END OF THE WAVE AT THE BASE OF AN
UPPER LEVEL TROUGH...GENERALLY FROM 19N-21N BETWEEN 62W-65W.

TROPICAL WAVE IS MOVING SLOWLY THROUGH THE WESTERN CARIBBEAN
ALONG 20N85W TO THE COAST OF HONDURAS ALONG 85W...MOVING WEST AT
5-10 KT. THE WAVE LIES WITHIN A BROAD AREA OF ENHANCED MOISTURE
OVER MUCH OF THE WESTERN CARIBBEAN. SCATTERED STRONG CONVECTION
IS EAST OF THE AXIS FROM 20N EXTENDING NORTHWARD OVER WESTERN
CUBA AND THE STRAITS OF FLORIDA BETWEEN 82W-85W. SCATTERED
MODERATE CONVECTION IS ALSO FROM 13N-19N BETWEEN 80W-84W. A
SHARP UPPER TROUGH OVER THE CENTRAL GULF OF MEXICO AND
ASSOCIATED STRONG DIFFLUENT FLOW ALOFT IS ENHANCING THIS
CONVECTION AND ADVECTING THE MOISTURE NORTHWARD.

...ITCZ/MONSOON TROUGH...
THE MONSOON TROUGH EXTENDS FROM THE COAST OF MAURITANIA NEAR
15N17W TO 11N20W TO 10N22W. THE ITCZ BEGINS NEAR 10N22W AND
CONTINUES ALONG 9N30W 4N40W TO THE COAST OF SOUTH AMERICA NEAR
2N51W. ISOLATED MODERATE CONVECTION IS FROM 3N-6N BETWEEN 37W-
41W. NO SIGNIFICANT CONVECTION ELSEWHERE ALONG THE AXIS.

...DISCUSSION...

GULF OF MEXICO...
A VERY SHARP UPPER LEVEL TROUGH FOR LATE JUNE CONTINUES TO DIG
SOUTHWARD INTO THE CENTRAL GULF OF MEXICO WITH AXIS EXTENDING
FROM EASTERN LOUISIANA NEAR 29N90W TO THE SW GULF NEAR 19N91W.
THE UPPER TROUGH SUPPORTS A COLD FRONT THAT AS OF 2100 UTC
EXTENDS FROM NEAR PENSACOLA FLORIDA THROUGH 28.5N90W TO 28N93W.
A PRE-FRONTAL SURFACE TROUGH EXTENDS FROM NEAR APALACHICOLA
FLORIDA TO 26N91W. COMPOSITE RADAR IMAGERY AND LIGHTNING DATA
INDICATE SCATTERED SHOWERS/THUNDERSTORMS ARE OCCURRING THROUGHOUT
THE GULF GENERALLY E OF 90W AND THE PRE-FRONTAL SURFACE TROUGH.
THE STRONGEST ACTIVITY IS OVER WESTERN CUBA...THE FLORIDA
STRAITS AND STREAMING NORTHWARD OVER THE FLORIDA PENINSULA.
TOTAL PRECIPITABLE WATER IMAGERY AND INDICATED THAT DEEP LAYERED
TROPICAL MOISTURE IS BEING ADVECTED FROM THE CARIBBEAN NORTHWARD
ACROSS FLORIDA AND ALONG THE EAST COAST OF THE U.S. MOST OF THE
GULF W OF 90W IS DOMINATED BY DRY AIR ALOFT WITH POCKETS OF MID
TO UPPER LEVEL MOISTURE NOTED. SOUTH TO SOUTHWEST WINDS ARE
IMPACTING THE GULF INCREASING FROM 5-10 KT IN THE SOUTHERN GULF
TO 15-20 KT NEAR THE SURFACE TROUGH. WINDS SHIFT TO THE
NORTHWEST TO THE WEST OF THE COLD FRONT AND SURFACE TROUGH. THE
FRONTAL BOUNDARY/SURFACE TROUGH WILL REMAIN ACROSS THE NORTHERN
GULF WITH MOIST CONDITIONS REMAINING OVER MUCH OF THE EASTERN
GULF OVER THE NEXT SEVERAL DAYS.

CARIBBEAN SEA...
A TROPICAL WAVE CONTINUES TO MOVE SLOWLY THROUGH THE WESTERN
CARIBBEAN ALONG 85W. 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. THE
NORTHERN PART OF THE TROPICAL WAVE AND ASSOCIATED CONVECTION IS
NOW BEING ENHANCED BY A VERY SHARP UPPER LEVEL TROUGH IN THE
CENTRAL GULF OF MEXICO. SOUTH OF THE WAVE...THE MONSOON TROUGH
EXTENDS FROM NORTHERN COLOMBIA TO THE BORDER OF COSTA RICA AND
NICARAGUA. WEAK UPPER RIDGING COVERS THE CENTRAL CARIBBEAN WITH
ONLY HIGH LEVEL MOISTURE NOTED. DRY AIR AT THE REMAINING LEVELS
IS KEEPING THIS PORTION OF THE BASIN RATHER CLEAR. THE EASTERN
CARIBBEAN IS IMPACTED BY A SECOND TROPICAL WAVE NEAR 65W/66W.
CONVECTION NEAR THE WAVE IS BEING SHEARED TO THE EAST DUE TO
SOUTHWESTERLY FLOW ALOFT AROUND AN UPPER TROUGH AND ELONGATED
UPPER LOW NEAR 26N64W. 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 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...
DIURNALLY ENHANCED CONVECTION IS OCCURRING OVER HISPANIOLA WITH
LIGHTNING DATA INDICATING FREQUENT CLOUD TO GROUND STRIKES.
MOISTURE AHEAD OF THE TROPICAL WAVE IN THE EASTERN CARIBBEAN AND
PRECIPITABLE WATER MAXIMA IN THE GLOBAL MODELS SHOULD REACH THE
ISLAND OVERNIGHT INTO MON...INCREASING THE CHANCES OF MORE
WIDESPREAD THUNDERSTORM ACTIVITY. MOISTURE DECREASES TUE AND WED
AS THE TROPICAL WAVE MOVES W OF THE AREA.

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 77W-80W
ASSOCIATED WITH MOIST AND DIFFLUENT FLOW ALOFT BETWEEN AN UPPER
TROUGH OVER THE GULF OF MEXICO AND A NARROW UPPER LEVEL RIDGE TO
THE EAST ALONG 74W. A BROAD UPPER LOW IS CENTERED NEAR 26N64W.
THE UPPER LOW IS ENHANCING SHOWER ACTIVITY ASSOCIATED WITH A
WEAK SURFACE TROUGH ALONG 36N56W TO 28N54W. A FEW ISOLATED
SHOWERS ARE WITHIN 75 NM EITHER SIDE OF THE TROUGH. A LARGER
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

$$
COBB


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