[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 271808
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT THU JUL 27 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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1730 UTC.

...TROPICAL WAVES...

TROPICAL WAVE IS ALONG 20W/21W S OF 20N MOVING W 15 TO 20 KT.
VISIBLE IMAGERY REVEALS SOME MOSTLY MID LEVEL CYCLONIC TURNING
ASSOCIATED WITH THIS WAVE. SCATTERED MODERATE CONVECTION LIES
FROM 7 TO 13N BETWEEN 18 AND 25W WHICH IS MOSTLY ASSOCIATED WITH
THE NEAR EQUATORIAL TROF ALONG THE ITCZ.

A HIGH AMPLITUDE TROPICAL WAVE IS ALONG 47W S OF 22N MOVING WEST
NEAR 15 KT. THIS LARGE WAVE REMAINS WELL DEFINED WITH CLEAR
LOW-MID LEVEL TURNING EVIDENT WITH AN INVERTED V PATTERN ON
SATELLITE IMAGERY. THE WAVE IS STILL ENHANCING CONVECTION
EMBEDDED WITHIN THE ITCZ FROM 7N TO 15N BETWEEN 43W-53W...BUT
HAS DIMINISHED IN BOTH COVERAGE AND INTENSITY SINCE THE
OVERNIGHT HOURS TO JUST ISOLATED MODERATE. CONVECTIVE ACTIVITY
MAY PULSE AGAIN THIS EVENING...ESP THE SOUTHERN PORTION...AS
CLOUD TOPS COOL WITH ENHANCED OUTGOING RADIATION. THE NORTHERN
EXTENSION OF THE WAVE HAS LIMITED SHOWER ACTIVITY AS IT REMAINS
EMBEDDED IN A DRY/STABLE ENVIRONMENT LIKELY DUE TO SAHARAN DUST.

A HIGH AMPLITUDE TROPICAL WAVE IS IN THE EASTERN CARIBBEAN ALONG
68W SOUTH OF 23N MOVING WEST NEAR 15 KT. THIS WAVE HAS BEEN
WELL-DEFINED OVER THE PAST SEVERAL DAYS. SHOWER AND TSTM
ACTIVITY HAS PERSISTED ALONG THE NORTHERN PORTION OF THIS WAVE
TODAY...WITH IR IMAGERY SHOWING SCATTERED MODERATE CONVECTION
FROM 18N TO 24N AND BETWEEN 63W AND 72W. THIS WILL CONTINUE
PUSHING WEST THROUGH NORTHERN HISPANIOLA...THE TURKS AND CAICOS
ISLANDS...BAHAMAS...AND POSSIBLY PARTS OF FLORIDA AS WE MOVE
INTO THE WEEKEND. HOWEVER...THIS SYSTEM IS NOT EXPECTED TO
DEVELOP INTO A TROPICAL CYCLONE AS IT ENCOUNTERS UNFAVORABLE
UPPER LEVEL WINDS AS IT INTERACTS WITH AN UPPER TROF TO ITS NW.

A TROPICAL WAVE IN THE WESTERN CARIBBEAN IS ALONG 84W/85W SOUTH
OF 19N MOVING WEST NEAR 15 KT. LOW CLOUD MOTIONS IN VISIBLE
SATELLITE IMAGERY THIS AFTERNOON SHOWS SOME BROAD/WEAK CURVATURE
ASSOCIATED WITH THIS WAVE...BUT OVERALL THE WAVE REMAINS
DIFFICULT TO DISCERN. A SMALL PATCH OF MODERATE CONVECTION LIES
EAST OF THIS WAVE OFF THE CARIBBEAN COAST OF NICARAGUA.

...ITCZ...
ITCZ AXIS IS CENTERED ALONG 11N14W 9N40W 10N63W THROUGH NORTHERN
VENEZUELA AND COLOMBIA TO NEAR 9N82W NEAR PANAMA. SCATTERED
MODERATE CONVECTION LIES FROM 7N TO 13N BETWEEN 18W AND 25W
THROUGH THE TROPICAL WAVE ALONG 21W. SCATTERED MODERATE
CONVECTION ALSO LIES WEST OF THIS WAVE FROM 5N TO 11N BETWEEN
26W AND 33W. A SMALL PATCH OF MODERATE CONVECTION NORTH OF THE
AXIS IS JUST EAST OF TRINIDAD AND TOBAGO.

...DISCUSSION...
GULF OF MEXICO...
THE GULF OF MEXICO IS NOW VOID OF SIGNIFICANT CONVECTION...WITH
THE SURFACE LOW THAT AFFECTED THE WESTERN GULF EARLIER IN THE
WEEK WELL NORTH/INLAND OF THE AREA AND DISSIPATING. THE WESTERN
EXTENSION OF AN ATLANTIC 500MB ANTICYCLONE COVERS MUCH OF THE
GULF THIS AFTERNOON. MOISTURE/WEAK LOW LEVEL CONVERGENCE BETWEEN
THE WESTERN PORTION OF THE ATLANTIC SFC HIGH WITH A WEAK SFC
HIGH NEAR ATLANTA GA IS PRODUCING A SMALL PATCH OF MODERATE
CONVECTION NEAR LAKE OKEECHOBEE AT 27/17Z. THE ANTICYCLONIC
TRACK OF THESE CLOUDS WILL PUSH WHATEVER IS LEFT INTO THE SW
GULF THIS EVENING. SFC WINDS AND SEAS IN THE EASTERN GULF REMAIN
LIGHT/LOW RESPECTIVELY WITH A LITTLE STRONGER SFC PRESSURE
GRADIENT...S/SE FLOW AND WIND WAVES IN THE WESTERN GULF. SIMILAR
CONDITIONS EXPECTED THROUGH FRI.

CARIBBEAN SEA...
TWO TROPICAL WAVES REMAIN IN THE CARIBBEAN SEA WITH THE WAVE
ALONG 68W THE MOST DEFINED AND CONVECTIVELY ACTIVE...AS IT
INTERACTS WITH AN UPPER LOW IN THE ATLC WATERS TO ITS NW. THIS
IS DISCUSSED IN DETAIL ABOVE IN THE TROPICAL WAVES SECTION. A
WEAK UPPER LOW IS NOTED IN WATER VAPOR IMAGERY THIS AFTERNOON IN
THE NW CARIBBEAN CENTERED NEAR 18N87W...WITH WEAK UPPER RIDGING
NOTED IN THE CENTRAL AND WESTERN CARIBBEAN SEA. THE SOUTHERN
PORTION OF THE BERMUDA HIGH CONTINUES TO EXTEND INTO THE
CARIBBEAN...WITH TRADE FLOW GENERALLY BETWEEN 10 AND 20 KT.

ATLANTIC OCEAN...
LARGE SCALE UPPER RIDGING CONTINUES TO DOMINATE MUCH OF THE
NORTH/CENTRAL ATLANTIC...WITH A COL REGION FOUND BETWEEN THIS
HIGH AND THE UPPER HIGH EXTENDING WEST FROM AFRICA NEAR 26N20W.
AN UPPER TROF JUST OFF THE SE/MIDATLANTIC EAST COAST ALONG WITH
SOME WEAK SFC CONVERGENCE IS GENERATING A BAND OF SCATTERED
MODERATE CONVECTION EXTENDING NE FROM PALM BEACH COUNTY INTO THE
ADJACENT ATLANTIC WATERS. ANOTHER UPPER LOW IS LOCATED JUST EAST
OF THE BAHAMAS NEAR 26N67W...AIDING THE TROPICAL WAVE ALONG 67W
IN ITS CONVECTION DEVELOPMENT. ANOTHER WEAK LOW/MID LEVEL
CYCLONIC SWIRL OF LOW/MID CLOUDS IS NOTED NEAR 29N36W. AT THE
SURFACE...A 1030MB SURFACE HIGH IS CENTERED NEAR 34N52W WITH
TRADE FLOW ROTATING LOW CLOUDS ANTICYCLONICALLY AROUND THE
TROPICAL ATLANTIC WATERS TO ITS SOUTH. A WIDESPREAD AREA OF
DENSE SAHARAN DUST EXTENDS OUT TO ABOUT 65W...BEHIND THE E
CARIBBEAN TROPICAL WAVE.

$$
WILLIS


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