[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 110006
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT TUE JUL 10 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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
2330 UTC.

...TROPICAL WAVES...

TROPICAL WAVE IS LOCATED ALONG 24W NEAR THE CAPE VERDE ISLANDS S
OF 18N MOVING WEST AT 10 TO 15 KT. SATELLITE IMAGERY REVEALS A
WEAK MID LEVEL CIRCULATION TRAILING THE WAVE TO THE E...NEAR
13N22W. NO SIGNIFICANT SHOWER OR TSTM ACTIVITY IS ASSOCIATED
WITH THIS WAVE.

TROPICAL WAVE ALONG 52W S OF 19N MOVING WEST AT 15 TO 20 KT. THE
WAVE HAS A WELL DEFINED SIGNATURE IN THE SSMI PRECIPITABLE WATER
LOOP...CORRESPONDING WELL WITH GOES SATELLITE IMAGERY AS WELL.
BUOYS 41040 AND 41101 TO THE NW OF THE WAVE CONTINUE TO SHOW
SLIGHT NE COMPONENT IN THE WIND FLOW. DIMINISHING SHOWER
ACTIVITY IS NOTED ALONG THE WAVE AXIS NEAR THE ITCZ.

TROPICAL WAVE ALONG 65W MOVING WEST AROUND 15 KT. THE WAVE
REMAINS WEAK AND VERY LOW AMPLITUDE WITH THE BEST SIGNATURE
EVIDENT ON ON SSMI PRECIPITABLE WATER LOOP. POSITION OF THIS
FEATURE IS BASED MAINLY ON CONTINUITY...ALTHOUGH A BRIEF SURGE
OF SCATTERED SHOWER ACTIVITY FROM EARLIER IN THE DAY N OF
VENEZUELAN COAST HINT OF THE WAVE'S PUSH INTO THE AREA.

A TROPICAL WAVE ALONG 79W MOVING WEST AT 10 TO 15 KT. THIS
FEATURE IS DIFFICULT TO PRECISELY LOCATED AS IT HAS VERY WEAK
STRUCTURE ON SATELLITE IMAGERY. HOWEVER...HOVMOLLER DIAGRAMS AND
ANIMATED SSMI PRECIPITABLE WATER LOOPS SHOW PERSISTENT AREA OF
MOISTURE MOVING INTO THE WESTERN CARIBBEAN. CLOSEST SHOWER AND
TSTM ACTIVITY IS WELL TO W ALONG THE NICARAGUAN COAST...AND
SEEMS TIED TO UPPER LEVEL FEATURES.

...THE ITCZ...
ITCZ AXIS IS CENTERED ALONG 13N17W 6N40W 8N52W 8N61W. SCATTERED
MODERATE CONVECTION WITHIN 120 NM N OF THE AXIS BETWEEN 25W AND
28W. SCATTERED MODERATE CONVECTION WITHIN 60 NM S OF AXIS
BETWEEN 32W AND 34W.

...DISCUSSION...
GULF OF MEXICO...
UPPER LEVEL ANTICYCLONE IS CENTERED OVER W COAST OF THE FLORIDA
PENINSULA NEAR 28N82W...AHEAD OF A WEAK UPPER LEVEL TROUGH
EXTENDING FROM 30N93W TO 25N97W. DIVERGENCE ALOFT IS ENHANCING
ISOLATED SHOWER AND TSTMS OVER THE EASTERN BAY OF CAMPECHE.
HOWEVER...GENERALLY DRY AIR IS GENERALLY PREVENTING SIGNIFICANT
CONVECTION OVER GULF WATERS. SHIP AND BUOY OBSERVATIONS ALONG
WITH EARLIER QUIKSCAT DATA SHOW LIGHT TO MODERATE SLY SURFACE
FLOW ACROSS GULF WATERS...ON THE WESTERN EDGE OF HIGH PRES
CENTERED OVER THE CENTRAL ATLC. THE UPPER RIDGE WILL SHIFT W
OVER THE NEXT COUPLE OF DAYS...WITH MINIMAL SHOWER OR TSTMS
ACTIVITY EXPECTED.

CARIBBEAN SEA...
AN UPPER LEVEL LOW IS CENTERED SW OF HAITI NEAR 17N75W. WHILE
THE UNSTABLE CENTER OF THE LOW IS ENHANCING AFTERNOON CONVECTION
OVER THE MOUNTAINS OF HISPANIOLA...DRY SUBSIDENT AIR IS EVIDENT
ACROSS THE CARIBBEAN BASIN N OF 17N. FURTHER S...UPPER RIDGE
AXIS EXTENDS ACROSS THE AREA S OF 17N...WITH WLY FLOW ALOFT
BRINGING INCREASED DEEP LAYER MOISTURE. UPPER DIVERGENCE ON THE
WRN PERIPHERY OF THE UPPER RIDGE IS ENHANCING CONVECTION ALONG
THE CARIBBEAN COAST OF NICARAGUA...IN ADVANCE OF AN APPROACHING
TROPICAL WAVE. AT THE SURFACE...STRENGTHENING SURFACE RIDGE TO
THE N IS ALLOWING FRESH TO STRONG TRADES OVER THE CENTRAL AND
WESTERN CARIBBEAN...AS EVIDENCED BY EARLIER QUIKSCAT PASS.
MODERATE TO FRESH ELY PERSIST OVER THE EASTERN
CARIBBEAN...ALTHOUGH THIS ACTIVITY MAY INCREASE SLIGHTLY AS
RIDGING BUILDS BEHIND TROPICAL WAVE.

ATLANTIC OCEAN...
UPPER TROUGH...EXTENDING FROM 32N40W TO 21N56W TO AN UPPER LOW
NEAR 17N57W...IS MAINTAINING FAIRLY DRY AIR N OF 17N W OF 40W.
ANOTHER UPPER TROUGH EXTENDS S TO 8N42W IS LIKEWISE MAINTAINING
DRY SUBSIDENT AIR OVER TROP N ATLC N OF ITCZ BETWEEN 38W AND
49W. W OF THIS TROUGH...UPPER LEVEL ANTICYCLONE IS CENTERED
GENERALLY NEAR 10N54W. UPPER DIVERGENCE AROUND SRN AND WRN EDGES
OF THIS ANTICYCLONE WILL ENHANCE SHOWERS IN VICINITY OF WAVE
NEAR 52W AS IT MOVES TOWARD LESSER ANTILLES TOMORROW. E OF THE
UPPER TROUGH IS ANOTHER UPPER ANTICYCLONE CENTERED NE OF CAPE
VERDE ISLANDS NEAR 18N22W. THIS MAY BE ENHANCING MINOR
CONVECTION ALONG THE ITCZ NEAR 33W...ALTHOUGH SHOWERS ARE FAIRLY
LIMITED ALONG WAVE NEAR 24W...AHEAD OF MID LEVEL LOW CENTER TO
THE E OF THE WAVE. AT THE SURFACE...MODERATE TO FRESH TRADE FLOW
REMAINS IN PLACE S OF 20N...S OF SURFACE RIDGE CENTERED OVER
CENTRAL ATLC.


$$
CHRISTENSEN




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