[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 281151
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
805 AM EDT TUE JUN 28 2011

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
1115 UTC.

...SPECIAL FEATURE...
BROAD LOW PRESSURE CONTINUES TO COVER THE SRN GULF OF MEXICO
WITH A 1007 MB SURFACE LOW LOCATED NEAR 20N93W...JUST E OF A
TROPICAL WAVE ALONG 94W/95W. CURRENTLY A LARGE AREA OF NUMEROUS
MODERATE/SCATTERED STRONG CONVECTION IS E OF THE LOW CENTER OVER
THE YUCATAN PENINSULA FROM 18N-22N BETWEEN 86W-93W. UPPER LEVEL
WINDS ARE CURRENTLY NOT FAVORABLE FOR DEVELOPMENT...BUT COULD
BECOME SO OVER THE NEXT COUPLE OF DAYS. REGARDLESS OF
DEVELOPMENT...SIGNIFICANT MOISTURE WILL REMAIN OVER THE SRN GULF
AND YUCATAN PENINSULA LIKELY SUPPORTING STRONG
SHOWERS/THUNDERSTORMS ALONG WITH GUSTY WINDS AS THE SYSTEM
DRIFTS WNW OVER THE NEXT 48 HOURS.

...TROPICAL WAVES...

A TROPICAL WAVE IS ACROSS THE CENTRAL ATLC ALONG 14N40W TO 6N42W
MOVING W NEAR 15 KT. THE FIRST VISIBLE SATELLITE IMAGES OF THE
DAY SHOW CLEAR LOW LEVEL CYCLONIC FLOW ABOUT THE WAVE AXIS. THE
WAVE IS EMBEDDED WITHIN A SURGE OF DEEP LAYER MOISTURE EVIDENT
IN TOTAL PRECIPITABLE WATER IMAGERY. SCATTERED MODERATE/ISOLATED
STRONG CONVECTION IS W OF THE WAVE AXIS FROM 9N-11N BETWEEN
42W-46W.

A TROPICAL WAVE EXTENDS ACROSS MONA PASSAGE INTO THE ERN
CARIBBEAN FROM 21N67W TO 14N69W MOVING W NEAR 15 KT. THE WAVE
LIES IN AN AREA OF MODERATE DEEP LAYER MOISTURE THAT IS ACROSS
THE ERN CARIBBEAN BETWEEN 65W-72W. AN UPPER LEVEL LOW JUST S OF
THE DOMINICAN REPUBLIC IS PROVIDING DIFFLUENCE ALOFT ABOVE THE
WAVE AXIS. THIS COMBINATION IS CAUSING A LARGE CLUSTER OF STRONG
CONVECTION NEAR THE NRN EXTENT OF THE WAVE FROM 20N-22N BETWEEN
65W-68W. POSSIBLE ISOLATED SHOWERS COVER THE AREA FROM 14N-20N
BETWEEN 67W-73W. THE UPPER LOW IS FORECAST TO DRIFT SW AS THE
WAVE MOVES W WHICH WILL CONTINUE TO PLACE THE WAVE UNDER
DIFFLUENCE ALOFT. EXPECT CONTINUED SHOWER/THUNDERSTORM ACTIVITY
OVER THE CENTRAL CARIBBEAN OVER THE NEXT 24 HOURS.

A TROPICAL WAVE IS OVER THE SW GULF OF MEXICO IN THE BAY OF
CAMPECHE ALONG 25N94W TO 17N95W DRIFTING WNW. THIS WAVE ALSO
LIES UNDER THE DIFFLUENT SIDE OF AN UPPER LEVEL TROUGH OVER THE
NW GULF WHICH IS HELPING ENHANCE CONVECTION. CLUSTERS OF
NUMEROUS STRONG CONVECTION ARE OVER SRN MEXICO FROM 13N-17N
BETWEEN 93W-96W. SCATTERED MODERATE/STRONG CONVECTION IS ALSO W
OF THE WAVE AXIS FROM 18N-22N BETWEEN 95W-99W. SCATTERED
MODERATE CONVECTION IS E OF THE WAVE AXIS FROM 22N-25N BETWEEN
93W-95W. A SURFACE LOW PRESSURE SYSTEM IS ALSO E OF THE WAVE
AXIS OFF THE COAST OF THE YUCATAN PENINSULA. THIS LOW...AS WELL
AS THE CONVECTION OVER THE YUCATAN PENINSULA IS DESCRIBED IN THE
SPECIAL FEATURES SECTION ABOVE. AT THIS TIME...THE WAVE IS
EXPECTED TO STAY SEPARATE FROM THE LOW PRESSURE SYSTEM AND WILL
MOVE INLAND OVER NE MEXICO AND DISSIPATE OVER THE NEXT 24 HOURS.

...ITCZ/MONSOON TROUGH...

THE MONSOON TROUGH EXTENDS ACROSS AFRICA FROM THE PRIME MERIDIAN
AT 19N ALONG 21N13W 13N17W 9N22W. THE ITCZ AXIS CONTINUES FROM
9N22W ALONG 6N33W 6N41W 2N52W. NUMEROUS MODERATE/SCATTERED
STRONG CONVECTION IS MOVING OFF THE W AFRICAN COAST FROM 6N-13N
BETWEEN 10W-18W...LIKELY ASSOCIATED WITH THE NEXT TROPICAL WAVE.
SIMILAR CONVECTION IS N OF BRAZIL FROM EQ-6N BETWEEN 46W-51W.

...DISCUSSION...

GULF OF MEXICO...
BROAD LOW PRESSURE CONTINUES TO IMPACT MUCH OF THE SRN GULF OF
MEXICO AS DISCUSSED IN THE SPECIAL FEATURE SECTION AND TROPICAL
WAVE SECTION. MOIST SWLY FLOW ALOFT COVERS MUCH OF THE BASIN
BETWEEN AN UPPER LEVEL TROUGH OVER THE NW GULF EXTENDING FROM
SRN MISSISSIPPI TO N CENTRAL MEXICO NEAR 23N101W...AND AN UPPER
LEVEL RIDGE EXTENDING FROM THE YUCATAN PENINSULA AND ACROSS THE
FLORIDA PENINSULA INTO THE W ATLC. THIS PATTERN IS ALSO CREATING
A LARGE AREA OF DIFFLUENCE ALOFT WHICH IS AIDING CONVECTION NEAR
BOTH THE TROPICAL WAVE AND THE SURFACE LOW. SCATTERED
SHOWERS/THUNDERSTORMS NOT ASSOCIATED WITH EITHER OF THOSE
FEATURES ARE ALSO IN THE SE GULF FROM 23N-27N BETWEEN
80W-87W...WITH POSSIBLE ISOLATED SHOWERS/THUNDERSTORMS ACROSS
FLORIDA AND THE NE GULF. DRY AIR COVERS THE NW GULF BEHIND THE
UPPER TROUGH PROVIDING FAIR WEATHER ACROSS THAT PORTION OF THE
BASIN. AT THE SURFACE...WEAK SURFACE RIDING IS OVER THE NE GULF
ALONG 29N EXTENDING FROM THE W ATLC. EXPECT SIGNIFICANT MOISTURE
TO REMAIN ACROSS THE AREA OVER THE NEXT SEVERAL DAYS WITH A HIGH
CHANCE OF PRECIPITATION.

CARIBBEAN SEA...
MUCH OF THE WRN CARIBBEAN IS EXPERIENCING FAIR WEATHER AS HIGH
MOISTURE VALUES HAVE NOW SHIFTED NW INTO THE SRN GULF OF MEXICO.
HOWEVER...SCATTERED SHOWERS/THUNDERSTORMS STILL REMAIN IN THE SW
CARIBBEAN S OF 15N BETWEEN 80W-84W...AND N OF HONDURAS FROM
16N-21N W OF 84W. ALOFT...DRY AIR IS BEING DRAWN OVER THE
CENTRAL CARIBBEAN BETWEEN AN UPPER LEVEL RIDGE EXTENDING FROM
THE YUCATAN PENINSULA TO FLORIDA...AND AN UPPER LEVEL LOW STILL
SPINNING JUST S OF THE DOMINICAN REPUBLIC NEAR 17N70W. THE UPPER
LOW IS INTERACTING WITH A TROPICAL WAVE OVER THE MONA PASSAGE.
THIS IS SUPPORTING ISOLATED SHOWERS N OF 14N BETWEEN
67W-73W...WITH AREAS OF STRONGER ACTIVITY N OF PUERTO RICO.
EXPECT SHOWER ACTIVITY TO CONTINUE OVER THE N CENTRAL CARIBBEAN
AS THE UPPER LOW DRIFTS SW AND THE WAVE MOVES W.

ATLANTIC OCEAN...
AN UPPER LEVEL TROUGH CONTINUES TO SIT OVER THE NW ATLC
SUPPORTING POSSIBLE ISOLATED SHOWERS ALONG A LINE FROM 28N81W TO
32N72W. AN UPPER LEVEL RIDGE IS TO THE E EXTENDING FROM SRN
FLORIDA TO NEAR 33N62W. AN UPPER LEVEL LOW JUST S OF THE
DOMINICAN REPUBLIC IS INTERACTING WITH A TROPICAL SUPPORTING A
LARGE CLUSTER OF STRONG SHOWERS/THUNDERSTORMS N OF PUERTO RICO
FROM 20N-22N BETWEEN 65W-68W. FARTHER E...SURFACE RIDGING
DOMINATES THE MAJORITY OF THE CENTRAL AND ERN TROPICAL ATLC
CENTERED AROUND A 1025 MB HIGH NEAR 31N54W SUPPORTED BY AN UPPER
LEVEL RIDGE CENTERED NEAR 15N55W. ANOTHER UPPER LEVEL LOW IS TO
THE N NEAR 26N50W SUPPORTING A WEAK SURFACE LOW N OF THE
DISCUSSION AREA. A SURFACE TROUGH EXTENDS FROM THE SURFACE LOW
INTO THE AREA ALONG 32N40W TO 28N44W. POSSIBLE ISOLATED SHOWERS
ARE ALONG THE TROUGH AXIS. A LONGWAVE UPPER TROUGH IS OVER THE
ERN ATLC N OF 20N ALONG 21W...WHILE AN UPPER RIDGE COVERS THE
TROPICAL ATLC CENTERED JUST W OF THE CAPE VERDE ISLANDS. A
SAHARAN AIR LAYER CONSISTING OF DRY AND DUSTY AIR CONTINUES TO
MOVE OVER THE ATLC MAINLY FROM 15N-24N FROM AFRICA TO THE ERN
CARIBBEAN.

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

$$
WALTON






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