[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 312337 AAA
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT MON JUL 31 2006

TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL
AMERICA...THE GULF OF MEXICO...THE CARIBBEAN SEA...NORTHEASTERN
SECTIONS OF SOUTH AMERICA...AND THE 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
2315 UTC.

...SPECIAL FEATURE...

A 1011 MB LOW HAS DEVELOPED ABOUT 200 MILES EAST OF THE LESSER
ANTILLES NEAR 16.5N 58.5W. SURFACE OBSERVATIONS INDICATE THAT
THIS WEAK CIRCULATION IS AT THE SURFACE. ASSOCIATED SHOWER
AND TSTM ACTIVITY IS LIMITED AND CONFINED TO A SMALL AREA FROM
15N-17.5N BETWEEN 56W-58.5W. ENVIRONMENTAL CONDITIONS ARE ONLY
MARGINALLY FAVORABLE FOR ADDITIONAL DEVELOPMENT...HOWEVER...ONLY
A SMALL INCREASE IN ORGANIZATION WOULD RESULT IN THE FORMATION
OF A TROPICAL DEPRESSION.  REGARDLESS IF THAT
OCCURS...SHOWERS...TSTMS AND SPORADIC GUSTY WINDS WILL BE
SPREADING ACROSS THE EASTERN CARIBBEAN ON TUE AS THIS SYSTEM
MOVES TO THE WEST-NORTHWEST AT ABOUT 10-15 KT.

...TROPICAL WAVES...
A TROPICAL WAVE IS ADDED TO THE 18 UTC SURFACE ANALYSIS NEAR THE
CAPE VERDE ISLANDS ALONG 23W/24W SOUTH OF 17N MOVING W NEAR 15
KT. SATELLITE IMAGERY FROM THIS EVENING CLEARLY SHOWS
WELL-DEFINED CYCLONIC CURVATURE AND A CLASSIC INVERTED V-SHAPE.
FURTHERMORE...THE DAKAR UPPER AIR TIME SECTION ANALYSIS SHOWS
THAT N WINDS VEERED SE INDICATING A WAVE PASSAGE ON SUNDAY. THIS
WAVE IS EMBEDDED IN A FAIRLY STABLE ENVIRONMENT LIKELY
SUPPRESSING ANY AREAS OF SIGNIFICANT CONVECTION. SCATTERED
SHOWERS ARE WITHIN 180 NM OF THE ANALYZED WAVE AXIS AND WITHIN
300 NM EAST OF THE AXIS. MORE CONCENTRATED ACTIVITY IS EMBEDDED
WITHIN THE ITCZ AHEAD OF THE WAVE.

A TROPICAL WAVE IS ALONG 62W/63W SOUTH OF 13N MOVING W NEAR 15
KT. YESTERDAY THIS FEATURE WAS ANALYZED AS A HIGH AMPLITUDE WAVE
ASSOCIATED WITH THE 1011 MB LOW EAST OF THE LESSER ANTILLES
WHICH IS DISCUSSED IN THE SPECIAL FEATURE SECTION ABOVE. SINCE
THEN...IT HAS BECOME MORE APPARENT ON SATELLITE IMAGERY AND THE
AVAILABLE SFC DATA THAT THE LOW PRES SYSTEM HAS BECOME DETACHED
FROM THE WAVE. THIS TROPICAL WAVE IS NOW FAIRLY LOW AMPLITUDE
BUT SEEMS TO BE ENHANCING CONVECTION OVER NORTHERN PORTIONS OF
SOUTH AMERICA SOUTH OF THE ITCZ...WHERE ISOLATED SHOWERS AND
TSTMS LIE FROM 2N TO 10N BETWEEN 62W AND 73W.

A TROPICAL WAVE IS ALONG 84W/85W SOUTH OF 21N MOVING WEST 15 TO
20 KT THROUGH THE WESTERN CARIBBEAN SEA. THIS WAVE HAS SOME
SLIGHT BROAD CYCLONIC TURNING EVIDENT ON SATELLITE IMAGERY AND
SURROUNDING BUOYS. THE WAVE INTERACTING WITH A WELL-DEFINED
UPPER LEVEL LOW MAY BE ENHANCING ISOLATED MODERATE CONVECTION
THAT IS DOTTING THE W CARIBBEAN FROM 12N TO 22N BETWEEN 79W AND
90W. MUCH MORE NUMEROUS MODERATE CONVECTION EXISTS ACROSS
JAMAICA...E CUBA...HISPANIOLA AND THE BAHAMAS...BUT THIS
UNSETTLED WEATHER IS PRIMARILY DUE TO UPPER DIFFLUENCE AND SFC
CONVERGENCE FROM A SFC TROF AND UPPER LOW.

THE EXTREME NORTHERN PORTION OF A MOSTLY E PACIFIC TROPICAL WAVE
ALONG 97W EXTENDS THROUGH S MEXICO. THIS WAVE IS NOT VERY WELL
DEFINED AND IS ONLY PRODUCING A FEW SCATTERED SHOWERS IN THE FAR
SW GULF OF MEXICO AND OVER S MEXICO. THIS FEATURE WILL CONTINUE
MOVING WEST OF THE AREA.

...ITCZ...
ITCZ AXIS IS CENTERED ALONG 12N15W 8N35W 13N54W 11N64W TO
PANAMA. BESIDES FOR THE CONVECTION ASSOCIATED WITH THE TROPICAL
WAVES...WEAKENING PATCHES OF MODERATE CONVECTION IS WITHIN 180
NM EITHER SIDE OF THE AXIS BETWEEN 26W-46W.

...DISCUSSION...
THE GULF OF MEXICO...
AN UPPER RIDGE CENTERED OVER THE SOUTHERN U.S. COVERS THE E GULF
AND FLORIDA. THIS UPPER HIGH IS ADVECTING A FAIR AMOUNT OF
MOISTURE FROM A MODERATE-HIGH UPPER DIFFLUENCE ZONE OFF THE EAST
COAST OF FLORIDA INTO THE NRN GULF. A SMALL WEAK UPPER LEVEL LOW
OVER THE FL PANHANDLE IS ENHANCING SOME OF THIS DIFFLUENCE ALONG
THE GULF COAST. SCATTERED SHOWERS AND TSTMS LIE N OF 27N E OF
91W. ELSEWHERE IN THE UPPER LEVELS...A SMALL UPPER LEVEL LOW IS
IN THE NW CORNER OF THE AREA NEAR 28N95W.  AN UPPER HIGH IS
CENTERED OVER S MEXICO NEAR 18N96W WITH BROAD RIDGING EXTENDING
INTO THE CARIBBEAN. MODERATE SUBSIDENCE LIES ABOVE THE CENTRAL
GULF. AT THE SFC...WEAK RIDGING IS THE THEME WITH A 1018 MB
HIGH CENTERED ALONG THE GEORGIA/FLORIDA BORDER. BROAD 10-15 KT
E-SELY FLOW DOMINATES THE REGION. LITTLE CHANGE IN THE SFC
PATTERN IS EXPECTED THRU MID-WEEK. FAIRLY DRY WEATHER IS
ANTICIPATED ACROSS MUCH OF THE REGION TOMORROW WITH THE BEST
CHANCE OF RAIN ON THE EDGES IN THE NRN AND SRN PORTIONS OF THE
GULF.

THE CARIBBEAN SEA...
CLUSTERS OF MODERATE CONVECTION HAS BLOSSOMED THIS LATE
AFTERNOON AND EVENING ACROSS JAMAICA...E CUBA...HAITI AND THE SE
BAHAMAS ASSOCIATED WITH STRONG UPPER DIFFLUENCE BETWEEN A
WELL-DEFINED LARGE UPPER LEVEL LOW CENTERED NEAR 25N72W AND AN
BROAD UPPER RIDGE STRETCHING FROM S MEXICO. THE UPPER LOW HAS A
SFC REFLECTION AS A TROUGH ALONG 72W EXTENDING FROM HAITI TO
27N. THIS CONVECTION COVERS A LARGE AREA NAMELY FROM 16N TO 22N
BETWEEN 69W AND 83W. THE MOST INTENSE OF THIS CONVECTION LIES ON
THE EASTERN PART OF JAMAICA AND BETWEEN EASTERN CUBA AND HAITI
WHERE CLOUD TOPS HAVE COOLED TO -78C TO -82C.  THE OTHER MAIN
FEATURE IS A 1011 MB LOW APPROACHING THE EASTERN CARIBBEAN...SEE
SPECIAL FEATURE. SHOWERS AND TSTMS WILL BEGIN MOVING INTO THE
LESSER ANTILLES LATE TONIGHT OR TOMORROW MORNING AND WILL BECOME
MUCH MORE NUMEROUS LATE TUE INTO WED. MODEST 10-15 KT E/SE SFC
WINDS DOMINATE MUCH OF THE CARIBBEAN SEA THIS EVENING...ROTATING
CLOCKWISE AROUND THE W/SW EXTENSION OF THE ATLANTIC HIGH. GFS
SUGGESTS SURFACE WINDS WILL INCREASE A TOUCH ESPECIALLY IN THE
CENTRAL CARIBBEAN OVER THE NEXT COUPLE OF DAYS AS THE GRADIENT
TIGHTENS BETWEEN A HIGH TO THE N/NE AND LOWER PRESSURE NEAR
COLOMBIA...ALONG WITH THE NEXT TROPICAL WAVE AND LOW PRES SYSTEM
PROPAGATING WNWWARD THRU THE AREA.

THE ATLANTIC OCEAN...
A SHARP UPPER TROUGH EXTENDS FROM 32N67W ACROSS THE BAHAMAS AND
TURKS AND CAICOS ISLANDS WITH A WELL-DEFINED UPPER LOW NEAR
25N72W. A 1010 MB LOW IS LOCATED A COUPLE HUNDRED MILES E OF
CAPE HATTERAS NORTH CAROLINA. STRONG UPPER LEVEL N/NE WINDS ON
THE NW PORTION OF THIS UPPER TROUGH ARE SHEARING THE CLOUD TOPS
LEAVING THE LOW LEVEL CENTER EXPOSED. UPPER DIFFLUENCE BETWEEN
THE UPPER TROUGH AND AN UPPER RIDGE CENTERED N OF THE VIRGIN
ISLANDS IS GENERATING SCATTERED SHOWERS AND TSTMS COVERING THE
REGION BETWEEN 62W-78W. THE MORE NUMEROUS CONVECTIVE ACTIVITY IS
IN THE CARIBBEAN WHERE UPPER DIFFLUENCE IS STRONGER. EAST OF THE
RIDGE...AN UPPER TROUGH EXTENDS FROM 32N44W TO NEAR 21N55W. AN
ASSOCIATED DISSIPATING COLD FRONT CLIPS THE AREA ALONG 32N50W
29N54W. FARTHER EAST...A LARGE UPPER RIDGE IS CENTERED JUST WEST
OF THE AFRICAN COAST NEAR 20N26W. NORTH OF THIS CENTER LIES AN
EXTENSIVE AREA OF DRY/STABLE UPPER LEVEL AIR ALONG WITH A DENSE
LAYER OF SAHARAN DUST SPREADING OUT TO ABOUT 48W. AT THE SFC...A
1027 MB HIGH IS CENTERED JUST SOUTH OF THE AZORES NEAR 36N27W
AND A 1022 MB HIGH IS CENTERED NEAR 25N49W.

$$
CANGIALOSI


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