[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 280550
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
205 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 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
0515 UTC.

...SPECIAL FEATURE...
BROAD LOW PRESSURE CONTINUES TO COVER THE SRN GULF OF MEXICO
WITH A 1006 MB SURFACE LOW LOCATED NEAR 19N92W...JUST E OF A
TROPICAL WAVE ALONG 94W/95W. THE LOW CENTER IS NOT WELL DEFINED
INDICATED BY A RECENT SCATTEROMETER PASS FROM 0352 UTC.
HOWEVER...20-25 KT WINDS ARE INDICATED TO THE N OF THE LOW AND
AROUND THE E SIDE OF THE TROPICAL WAVE. CURRENTLY A LARGE
CLUSTER OF NUMEROUS CONVECTION IS E OF THE LOW CENTER OVER NRN
GUATEMALA AND THE YUCATAN PENINSULA FROM 16N-20N BETWEEN
88W-91W...AND OVER THE NRN YUCATAN PENINSULA FROM 20N-22N
BETWEEN 87W-89W. 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 14N38W TO 5N39W
MOVING W NEAR 15 KT. A RECENT SCATTEROMETER PASS FROM 0026 UTC
SHOWS CLEAR CUT CYCLONIC SURFACE FLOW IS ABOUT THE WAVE AXIS.
THE WAVE IS EMBEDDED WITHIN A SURGE OF DEEP LAYER MOISTURE
EVIDENT IN TOTAL PRECIPITABLE WATER IMAGERY. SCATTERED
MODERATE/STRONG CONVECTION IS W OF THE WAVE AXIS FROM 9N-11N
BETWEEN 41W-46W.

A TROPICAL WAVE EXTENDS ACROSS WRN PUERTO RICO AND THE ERN
CARIBBEAN FROM 20N66W TO 11N68W MOVING W NEAR 15 KT. THE WAVE
LIES IN AN AREA OF MODERATE DEEP LAYER MOISTURE THAT IS ACROSS
THE ERN CARIBBEAN. AN UPPER LEVEL LOW JUST S OF THE DOMINICAN
REPUBLIC IS PROVIDING DIFFLUENCE ALOFT ABOVE THE WAVE AXIS. THIS
COMBINATION IS CAUSING A CLUSTER OF STRONG CONVECTION NEAR THE
NRN EXTENT OF THE WAVE FROM 19N-20N BETWEEN 64W-67W. MODERATE
CONVECTION IS ALSO ACROSS MUCH OF THE DOMINICAN REPUBLIC AND
NEAR THE WAVE AXIS FROM 14N-16N BETWEEN 66W-68W. POSSIBLE
ISOLATED SHOWERS COVER THE REMAINDER OF THE AREA FROM 14N-21N
BETWEEN 64W-72W. 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 WRN MEXICO FROM 14N-19N
BETWEEN 93W-95W. SCATTERED MODERATE/STRONG CONVECTION IS ALSO W
OF THE WAVE AXIS FROM 15N-21N BETWEEN 95W-99W...AND NEAR THE
WAVE AXIS FROM 22N-24N BETWEEN 92W-95W. A SURFACE LOW PRESSURE
SYSTEM IS ALSO E OF THE WAVE AXIS NEAR 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 23N ALONG 20N08W 16N15W TO 7N19W. THE ITCZ AXIS CONTINUES
FROM 7N19W ALONG 7N31W 7N40W 5N57W. A LARGE BURST OF NUMEROUS
STRONG CONVECTION IS MOVING OFF THE W AFRICAN COAST FROM 8N-16N
BETWEEN 13W-17W...LIKELY ASSOCIATED WITH THE NEXT TROPICAL WAVE.
ISOLATED MODERATE/STRONG CONVECTION IS FROM 7N-10N BETWEEN
18W-21W...AND WITHIN 100 NM S OF THE AXIS BETWEEN 28W-33W.
SCATTERED MODERATE/STRONG CONVECTION IS N OF BRAZIL FROM EQ-6N
BETWEEN 45W-50W.

...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 ALABAMA TO N CENTRAL MEXICO NEAR 22N100W...AND AN UPPER
LEVEL RIDGE EXTENDING FROM THE NW CARIBBEAN AND ACROSS THE
FLORIDA PENINSULA. THIS PATTERN IS ALSO CREATING A LARGE AREA OF
DIFFLUENCE 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-26N BETWEEN 81W-88W...WITH 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 NRN GULF ALONG 28N 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...
PORTIONS OF THE WRN CARIBBEAN ARE FINALLY GETTING SOME RELIEF
FROM THE MOISTURE THAT HAS NOW MOVED OVER THE GULF OF MEXICO.
HOWEVER...SCATTERED SHOWERS/THUNDERSTORMS STILL REMAIN OVER
CENTRAL AMERICA INCLUDING NICARAGUA...HONDURAS...GUATEMALA...AND
BELIZE. MOST OF THE ACTIVITY OVER CUBA HAS NOW DIED DOWN LEAVING
THE REMAINDER OF THE WRN CARIBBEAN W OF 72W UNDER MOSTLY FAIR
CONDITIONS. ALOFT...DRY AIR IS BEING DRAWN OVER THE CENTRAL
CARIBBEAN BETWEEN AN UPPER LEVEL RIDGE EXTENDING FROM THE NW
CARIBBEAN 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 BETWEEN 66W-68W. THIS IS
SUPPORTING ISOLATED SHOWERS N OF 14N BETWEEN 64W-72W...WITH
AREAS OF STRONGER ACTIVITY N OF PUERTO RICO AND OVER THE
DOMINICAN REPUBLIC. EXPECT SHOWER ACTIVITY TO INCREASE 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 28N79W TO
32N70W. AN UPPER LEVEL RIDGE IS TO THE E EXTENDING FROM SRN
FLORIDA TO NEAR 34N61W SANDWICHED BETWEEN THE UPPER TROUGH AND A
SEPARATE UPPER LEVEL LOW NOW JUST S OF THE DOMINICAN REPUBLIC. A
LARGE CLUSTER OF STRONG SHOWERS/THUNDERSTORMS IS N OF PUERTO
RICO FROM 19N-20N BETWEEN 64W-67W NEAR THE NRN EXTENT OF A
TROPICAL WAVE IN THE CARIBBEAN. FARTHER E...SURFACE RIDGING
DOMINATES THE MAJORITY OF THE CENTRAL AND ERN TROPICAL ATLC
CENTERED AROUND A 1025 MB HIGH NEAR 31N53W SUPPORTED BY AN UPPER
LEVEL RIDGE CENTERED NEAR 14N55W. ANOTHER UPPER LEVEL LOW IS TO
THE N NEAR 27N51W SUPPORTING A WEAK SURFACE LOW N OF THE
DISCUSSION AREA. A LONGWAVE UPPER TROUGH IS OVER THE ERN ATLC N
OF 23N ALONG 26W...WHILE AN UPPER RIDGE COVERS THE TROPICAL ATLC
CENTERED OVER 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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