[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 061757
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT MON AUG 06 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
1745 UTC.

...TROPICAL WAVES...
A LOW AMPLITUDE TROPICAL WAVE HAS BEEN ADDED ALONG 24/25W S OF
15N...ESTIMATED TO BE MOVING W NEAR 15 KT. THIS WAVE SHOWS UP
WELL IN THE METSAT-9 HOVMOLLER DIAGRAM. ALTHOUGH LITTLE EVIDENCE
WAS NOTED IN THE DAKAR RAOB DATA...THE FEATURE DID APPEAR TO
PASS BAMAKO MALI LATE ON AUG 3. SCATTERED MODERATE TO STRONG
CONVECTION IS FROM 9N-13N BETWEEN 24W-28W.

HIGH AMPLITUDE TROPICAL WAVE IS ALONG 37W S OF 26N MOVING W NEAR
20 KT. THIS WAVE CONTINUES TO EXHIBIT A LARGE INVERTED V SHAPE
IN THE SURROUNDING STRATOCUMULUS CLOUDS. DEEP CONVECTION REMAINS
LIMITED TO THE SRN PORTION OF THE AXIS WHERE IT INTERSECTS WITH
THE ITCZ...WITH SCATTERED MODERATE FROM 9N-14N BETWEEN 32W-40W.

TROPICAL WAVE IS ALONG 48W S OF 18N MOVING W NEAR 10 KT. THIS
WAVE REMAINS LOW AMPLITUDE AND FAIRLY DIFFICULT TO TRACK.
HOWEVER...THERE SEEMS TO BE A LITTLE MORE LOWER TO MID LEVEL
CYCLONIC TURNING NOTED TODAY FROM 8N-14N BETWEEN 45W-50W...WHICH
MATCHES UP WELL WITH A MAXIMUM IN THE SATELLITE DERIVED 850 MB
VORTICITY PRODUCT FROM UW-CIMSS. REGARDLESS DEEP CONVECTION
REMAINS MINIMAL AND EMBEDDED IN THE ITCZ.

TROPICAL WAVE IS ALONG 68W S OF 21N MOVING W NEAR 15 KT. WAVE
NOW APPEARS TO BE W OF THE UPPER LEVEL LOW/TROUGH THAT EXTENDS
OVER THE LEEWARD/VIRGIN ISLANDS. EXACT WAVE POSN REMAINS
DIFFICULT TO LOCATE DUE TO THE MOISTURE THAT HAS PERSISTED
FURTHER E NEAR THE UPPER DIFFLUENT ZONE AHEAD OF THE SLOW
MOVING UPPER LOW. NONETHELESS...A WWD SURGE OF MOISTURE IS STILL
EVIDENT IN THE UW-CIMSS TPW PRODUCT WHERE THE CURRENT AXIS IS
PLACED. ISOLATED SHOWERS/TSTMS ARE WITHIN 120 NM EITHER SIDE OF
THE AXIS MAINLY N OF 15N.

TROPICAL WAVE IS ALONG 95W S OF 22N MOVING W NEAR 15 KT. A WEAK
1013 MB LOW WAS ADDED TO THE AXIS IN THE SW BAY OF CAMPECHE NEAR
19N ON THE 1500 UTC MAP. THIS SYSTEM IS EXPECTED TO MOVE INLAND
LATER TODAY AND SIGNIFICANT DEVELOPMENT IS NOT ANTICIPATED.
ASSOCIATED SCATTERED MODERATE CONVECTION IS FROM 19N-21N W OF
94W.

...THE ITCZ...
ITCZ AXIS IS CENTERED ALONG 14N16W 12N22W 11N30W 10N42W 11N57W
10N62W. OUTSIDE OF THE CONVECTION MENTIONED WITH THE TROPICAL
WAVES...SCATTERED MODERATE IS WITHIN 60 NM EITHER SIDE OF THE
AXIS BETWEEN 40W-44W.

DISCUSSION...
GULF OF MEXICO...
A WEAK 1018 MB SFC HIGH IS S OF NEW ORLEANS OVER THE CENTRAL
GULF NEAR 27N89W. THIS IS PRODUCING MOSTLY LIGHT WINDS/LOW SEAS
ACROSS THE GULF EXCEPT SLIGHTLY HIGHER NEAR THE TROPICAL
WAVE/LOW EXITING THE FAR SW PORTION. LIGHTNING DATA DEPICTS
ISOLATED TSTMS ABOUT 200 NM OFF THE COAST OF S TEXAS FROM
25N-28N BETWEEN 90W-95W. THIS SEEMS MOST ASSOCIATED WITH A SMALL
UPPER DIFFLUENT ZONE AROUND THE PERIPHERY OF AN UPPER HIGH OVER
THE BAY OF CAMPECHE...BUT LOWER LEVEL MOISTURE ALSO SEEMS TO
HAVE BEEN INCREASED A BIT IN THE REGION FROM THE RECENT TROPICAL
WAVE. SCATTERED TSTMS THAT WERE OCCURRING IN THE NRN GULF JUST S
OF THE FLORIDA PANHANDLE AND ALABAMA EARLIER THIS MORNING HAVE
MOSTLY DIMINISHED. WEAK SFC HIGH PRES LOOKS TO DOMINATE THE
BASIN OVER THE NEXT FEW DAYS KEEPING WINDS LIGHT/SEAS LOW.

CARIBBEAN SEA...
THE MOST ACTIVE WEATHER IN THE CARIBBEAN IS OVER THE SW
PORTION/N OF PANAMA. SCATTERED MODERATE CONVECTION IS S OF 13N
BETWEEN THE COAST OF COLOMBIA AND 83W. UPPER DIFFLUENCE IS
LIKELY ENHANCING THIS ACTIVITY IN ADDITION TO LOW LEVEL SUPPORT
FROM THE ITCZ. OUTSIDE OF THIS ACTIVITY AND THE TROPICAL WAVE
ALONG 68W THE CARIB IS FAIRLY TRANQUIL. UPPER NE FLOW AND DRY
AIR ARE ROTATING AROUND THE HIGH OVER THE BAY OF CAMPECHE IS
OVER THE WRN CARIBBEAN. THERE IS A SWATH OF UPPER MOISTURE NOTED
BETWEEN THE COASTS OF JAMAICA AND HONDURAS THOUGH. UPPER
TROUGHING DOMINATES THE NE PORTION ASSOCIATED WITH THE UPPER LOW
N OF THE LEEWARD ISLANDS NEAR 21N63W. RADAR DATA FROM SAN JUAN
PUERTO RICO SHOWS SCATTERED SHOWERS IN THE VICINITY DUE TO THE
DESTABILIZATION ASSOCIATED WITH THE UPPER LOW...TROPICAL
WAVE...DAYTIME HEATING...AND NORMAL TRADE WIND MOISTURE. LIGHT
TO MODERATE TRADES ARE IN PLACE AND EXPECTED TO PERSIST OVER THE
NEXT COUPLE OF DAYS.

ATLANTIC OCEAN...
A WEAK 1013 MB SFC LOW IS OVER THE WRN ATLC NEAR 30N73W THAT HAS
A TROUGH EXTENDING SW TO NEAR PALM BEACH. ISOLATED SHOWERS AND
TSTMS ARE GENERALLY WITHIN 210 NM AHEAD OF THESE FEATURES. A
MORE RECENT FLARE UP OF SCATTERED MODERATE CONVECTION IS IN THE
LOW LEVEL CONFLUENT ZONE N OF 27N BETWEEN 62W-65W...WHICH IS
ALSO BEING SUPPORTED BY A WEAK UPPER TROUGH EXTENDING SW FROM
BERMUDA TO NEAR 25N68W. SKIES ARE MOSTLY FEW TO CLEAR BEHIND THE
SFC FEATURES TO THE COAST OF FLORIDA WITH UPPER NE FLOW AROUND A
LARGE UPPER ANTICYCLONE CENTERED OVER TENNESSEE. LIFT AHEAD OF
THE UPPER LOW NEAR 21N63W IS SUPPORTING WIDESPREAD CLOUDINESS
WITH POSSIBLE SHOWERS FROM 14N-26N BETWEEN 57W-63W. AN UPPER
HIGH IS CENTERED OVER THE TROPICAL ATLC NEAR 12N56W WITH ANOTHER
LARGE UPPER HIGH OVER THE E ATLC NEAR 26N27W. AN ELONGATED UPPER
TROUGH BETWEEN THE TWO HIGHS IS ALONG 44W. THIS FEATURE IS ONLY
GENERATING PATCHES OF CIRRUS N OF 25N BETWEEN 34W-40W. THE
REMAINDER OF THE SFC PATTERN E OF 55W IS DOMINATED BY MODERATE
TRADES ON THE SRN PERIPHERY OF A 1029 MB HIGH SW OF THE AZORES
NEAR 35N34W. NE SFC WINDS REMAIN A LITTLE STRONG NEAR THE COAST
OF NW AFRICA WITH A TIGHTER GRADIENT THERE.

$$
WILLIS




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