[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 071741
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT THU JUN 07 2007

TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL
AMERICA...THE GULF OF MEXICO...THE CARIBBEAN SEA...NORTHERN
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...METEOROLOGICAL ANALYSIS...
WEATHER OBSERVATIONS...AND RADAR.

BASED ON 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY
THROUGH 1715 UTC.

...TROPICAL WAVES...

A TROPICAL WAVE IS ADDED TO THE 12Z ANALYSIS ALONG 27W S OF 12N.
A LOOP OF SATELLITE AND SFC DATA SHOW THAT THIS WAVE EMERGED
OFF THE W COAST OF AFRICA EARLY ON JUNE 5TH...SO AN ESTIMATED
SPEED OF THE WAVE IS WWD 15-20 KT. THERE IS A FAIR AMOUNT OF LOW
TO MID LEVEL CYCLONIC TURNING IN THE CLOUDS OVER A 8-10 DEG
AREA. THIS SIGNATURE ALONG WITH A PAIR SWLY WIND REPORTS FROM
TWO SHIPS IN THE VICINITY OF 5N26W AND AN 08Z QSCAT PASS HELPED
DEFINE THE WAVE AXIS. ISOLATED MODERATE CONVECTION IS WITHIN 90
NM E AND 180 NM W OF THE AXIS.

A TROPICAL WAVE HAS BEEN REPOSITIONED ALONG 47W/48W S OF 11N
ESTIMATED TO BE MOVING W AROUND 15 KT. AS MENTIONED IN THIS
MORNING'S DISCUSSION...SATELLITE HOVMOLLER DIAGRAMS SUGGEST THE
FEATURE IS MUCH FURTHER W THAN PREVIOUS THOUGHT. THESE DIAGRAMS
SHOW GOOD WWD CONTINUITY IN THE CONVECTIVE BURSTS WHICH BEGAN TO
FADE NEAR 35W ON JUNE 4TH. BASED ON EXTRAPOLATION AND A NOTABLE
PERTURBATION IN THE ITCZ SEEN ON VIS PICTURES...THIS PSN APPEARS
REASONABLE. SCATTERED SHOWERS ARE WITHIN 120 NM OF THE AXIS.

A TROPICAL WAVE IS PUSHING ACROSS THE ERN CARIB ISLANDS ALONG
61W S OF 14N MOVING W NEAR 15 KT. SCATTERED SHOWERS AND TSTMS
ASSOCIATED WITH THE WAVE ARE AFFECTING THE REGION FROM 11N-14N
BETWEEN 56W-63W...WHICH INCLUDES THE WINDWARD ISLANDS. THIS WAVE
DOES HAVE SOME STRUCTURE...EASILY SEEN ON SATELLITE IMAGES...
WITH SOME TURNING IN THE LOW-LEVEL WINDS...HOWEVER THE HIGHEST
AMPLITUDE IS OFF THE SFC. UPPER W TO SWLY FLOW ALONG AND E OF
THE WAVE AXIS...ASSOCIATED WITH AN UPPER LOW IN THE CENTRAL
ATLC...IS THE CULPRIT IN SPREADING SOME OF THIS MOISTURE IN A
LINEAR FASHION WELL E OF THE WAVE AXIS. THIS FEATURE WILL LIKELY
SPREAD MOISTURE ACROSS THE SRN CARIB OVER THE NEXT COUPLE OF
DAYS.

A TROPICAL WAVE HAS PUSHED OFF THE COAST OF WRN COLOMBIA
ANALYZED ALONG 79W S OF 12N MOVING W 10-15 KT. HOWEVER...LOOKING
AT THE LATEST DATA THE WAVE AXIS COULD BE FURTHER W CLOSER TO
82W WHERE A FEW SMALL CLUSTERS OF SCATTERED MODERATE CONVECTION
HAS DEVELOPED PUSHING W OVER NICARAGUA AND COSTA RICA. SIMILAR
CLUSTERS LIE FURTHER S ACROSS THE EPAC WATERS...SEE MIATWDEP FOR
DETAILS THERE.

...THE ITCZ...

ITCZ AXIS IS CENTERED ALONG 7N10W 5N20W 7N24W 5N30W 5N46W 4N53W.
BESIDES FOR CONVECTION MENTIONED WITH THE TROPICAL WAVES...
SCATTERED MODERATE HAS PUSHED OFF THE COAST OF W AFRICA E OF 15W
FROM 4N-9N. THIS ACTIVITY IS LIKELY AHEAD OF THE NEXT WAVE STILL
INLAND OVER THE CONTINENT.

...DISCUSSION...

THE GULF OF MEXICO...
UPPER RIDGING CENTERED IN THE NW GULF NEAR 29N92W IS PROVIDING A
MUCH MORE STABLE AIRMASS THAN WHAT WAS IN PLACE ACROSS THIS
REGION YESTERDAY ALLOWING SKIES TO BE FAIR TO MOSTLY CLEAR
ACROSS THE CENTRAL AND WRN GULF. CONDITIONS ARE A BIT MORE MOIST
IN THE E GULF WHERE DOPPLER RADAR IS DETECTING SOME ISOLATED
SHOWER ACTIVITY IN LONG RANGE....HOWEVER CLEARLY THE STRONGEST
LIFT IS WELL E OF THE AREA. THIS WEAK ACTIVITY IS ASSOCIATED
WITH SOME LEFTOVER MOISTURE NEAR THE BASE OF AN UPPER SHORTWAVE
WHICH EXTENDS ACROSS THE FL BIG BEND AND MOIST LOW-LEVEL RETURN
FLOW. THE LOW-LEVEL FLOW IS NEARLY UNIFORM S-SELY ACROSS THE
REGION ON THE W PERIPHERY OF AN ATLC RIDGE...STRONGEST IN THE W
GULF WHERE BUOYS/SHIPS AND A 12Z QSCAT PASS DEPICT WIND IN THE
20-25 KT RANGE. THIS STRONG FLOW IS EXPECTED TO PERSIST FOR
ANOTHER DAY...RELAXING THEREAFTER AS WEAK SFC RIDGING BUILDS
OVERHEAD.

THE CARIBBEAN SEA...
THE AREAS OF MORE ACTIVE WEATHER IN THIS REGION LIE IN THE SW
AND SE CORNERS ASSOCIATED WITH TROPICAL WAVES. FOR DETAILS REFER
TO THAT SECTION ABOVE. OTHERWISE...A STRONG SPRAWLING UPPER HIGH
CENTERED ABOVE THE NW CARIB NEAR 19N85W DOMINATES PRODUCING
PLENTY OF DRY AIR ALOFT ACROSS NEARLY THE ENTIRE REGION. THIS
STABLE AIRMASS IS PROVIDING A CAP SUPPRESSING MOST OF THE DEEP
CLOUDINESS. THE TIGHT SFC PRES GRADIENT...BETWEEN HIGH PRES TO
THE N AND LOWER PRES ASSOCIATED WITH TROPICAL WAVES PUSHING W
ALONG THE ITCZ....IS PRODUCING ELY TRADES MOSTLY IN THE 15-25 KT
RANGE...POSSIBLY SLIGHTLY STRONGER IN THE SW CARIB JUST N OF THE
COLOMBIAN COAST. THESE TRADES ARE CARRYING TYPICAL PATCHES OF
LOW LEVEL MOISTURE/ISOLATED SHOWERS WWD ACROSS THE BASIN...MOST
CONCENTRATED N OF 14N E OF 74W. LOOKING AHEAD A COUPLE OF
DAYS...THE FEATURE OF HIGHEST INTEREST IS THE TROPICAL WAVE IN
THE WINDWARD ISLANDS. THIS WAVE MAY CONTINUE TO SPREAD MOISTURE
ACROSS THE SE/SRN CARIB AS THE FEATURE TRACKS W.

THE ATLANTIC OCEAN...
A TYPICAL SUMMERTIME SFC RIDGE AXIS EXTENDS W ACROSS THE WRN
ATLC WHICH IS PRODUCING LIGHT WINDS AND LOW SEAS.
HOWEVER...EXTENSIVE DEEP LAYER MOISTURE IS OVER THE REGION
ASSOCIATED WITH UPPER DIFFLUENCE AHEAD OF A SHORTWAVE TROUGH
NEAR THE SE CONUS COAST AND A MUCH BROADER AMPLIFIED TROUGH
FURTHER NE. BROKEN TO OVERCAST CLOUDS WITH EMBEDDED
SHOWERS/TSTMS OCCUPY THE WRN ATLC AREA FROM 26N-30N BETWEEN
58W-79W. TSTM ACTIVITY HAS GENERALLY BEEN ON THE INCREASE THIS
AFTERNOON WITH A NEW BURST FORMING OVER THE CENTRAL BAHAMAS.
FARTHER E...A MID TO UPPER LOW IS OVER THE CENTRAL ATLC NEAR
24N48W. THIS MAY BE GENERATING A FEW ISOLATED SHOWERS/TSTMS
WITHIN 240 NM IN THE NRN SEMICIRCLE. OTHERWISE...THE CENTRAL
ATLC...AND MUCH OF THE E ATLC WATERS IS DOMINATED BY FAIR
WEATHER AND LIGHT TO MODERATE WINDS S OF A STATIONARY 1027 MB
HIGH NEAR 39N43W. A WEAK COLD FRONT EXTENDS SE FROM AN OCCLUDED
998 MB LOW NEAR THE ERN AZORES ALONG 32N15W 26N23W 26N37W. THIS
FRONT IS EXPECTED TO SLOWLY DISSIPATE OVER THE NEXT DAY OR TWO
AS THE LOW FILLS AND PULLS OFF TO THE NE.

$$
CANGIALOSI


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