[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 182350
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT MON JUN 18 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
2315 UTC.

...TROPICAL WAVES...

A LARGE AMPLITUDE TROPICAL WAVE EXTENDS FROM 15N53W TO SURINAME
MOVING WEST 15 KT. THIS IS A WELL DEFINED BROAD WAVE APPROACHING
THE WINDWARD ISLANDS. SCATTERED MODERATE CONVECTION IS WITHIN
200 NM EITHER SIDE OF THE WAVE AXIS FROM 9N-12N. CLUSTERS OF
MODERATE CONVECTION ARE ALONG THE SURINAME/FRENCH GUIANA BORDER.
MOISTURE FROM THIS WAVE SHOULD BEGIN TO AFFECT THE WINDWARD
ISLANDS EARLY TUE...AND PUERTO RICO AND THE VIRGIN ISLANDS ON
WED.

A SOUTHWESTERN CARIBBEAN SEA TROPICAL WAVE IS ALONG 82W/83W
SOUTH OF 14N MOVING WEST 10 TO 15 KT. THIS WAVE DOES NOT SHOW UP
WELL ON SATELLITE IMAGERY. MOST OF THE CONVECTIVE ACTIVITY IS
WITHIN THE ITCZ OVER COSTA RICA AND PANAMA WHERE SATELLITE
IMAGERY SHOWS CLUSTERS OF SCATTERED MODERATE CONVECTION.

...THE ITCZ...

THE ITCZ AXIS IS CENTERED ALONG 11N15W 6N30W 6N40W 7N50W 8N60W.
A LARGE CLUSTER OF MODERATE TO STRONG CONVECTION IS MOVING OUT
OF AFRICA COVERING FROM 10N-15N BETWEEN 10W-16W. WIDELY
SCATTERED MODERATE CONVECTION IS FROM 5N-11N BETWEEN 21W-28W.
ALTHOUGH THIS CONVECTIVE ACTIVITY HAS A GOOD CONTINUITY ON THE
HOVMOLLER DIAGRAM...IT HAS DIMINISHED SINCE YESTERDAY. WILL
CONTINUE TO MONITOR THIS ACTIVITY THAT MAY BE ASSOCIATED WITH A
NEW TROPICAL WAVE. SCATTERED MODERATE/ISOLATED STRONG CONVECTION
IS FROM 3N-6N BETWEEN 30W-42W.

...DISCUSSION...

THE GULF OF MEXICO...
AS OF 2100 UTC...A 1021 SFC HIGH IS CENTERED OVER THE W ATLANTIC
NEAR 29N74W. HIGH PRESSURE RETURN FLOW FROM THIS HIGH DOMINATES
THE GULF OF MEXICO. 10-20 KT SLY FLOW COVERS THE ENTIRE AREA.
MOIST ONSHORE FLOW IS PRODUCING SCATTERED MODERATE CONVECTION
WITH NUMEROUS LIGHTNING STRIKES OVER THE NE CORNER OF THE GULF
FROM 27N-31N BETWEEN 84W-91W. THIS SHOWER/TSTM ACTIVITY IS ALSO
AFFECTING THE FLORIDA PANHANDLE...SOUTHERN ALABAMA AND SE
LOUISIANA. DIFFLUENCE ASSOCIATED WITH AN UPPER RIDGE THAT COVERS
THE ENTIRE GULF IS ENHANCING THIS ACTIVITY. THE RIDGE IS
ANCHORED ON A HIGH LOCATED OVER THE BAY OF CAMPECHE NEAR 21N94W.
THERE ARE SOME SHOWERS OVER THE BAY OF CAMPECHE WHILE CONVECTION
CONTINUES TO FLARE UP EVERY AFTERNOON OVER SOUTH-CENTRAL
FLORIDA. EXPECT MORE OF THE SAME DURING THE NEXT 24 HOURS.

THE CARIBBEAN SEA...
A DRY AND STABLE AIRMASS IS DOMINATING THE BASIN...WITH 20 KT
TRADEWINDS COVERING A LARGE PORTION OF THE CARIBBEAN S OF 18N
BETWEEN THE WINDWARD ISLANDS AND 85W. CLUSTERS OF MODERATE
CONVECTION ARE OVER NORTHERN VENEZUELA AS WELL AS OVER COSTA
RICA AND PANAMA MAINLY ASSOCIATED WITH THE ITCZ AXIS ALONG
8N/9N. ALOFT...THE UPPER LEVEL HIGH OVER THE BAY OF CAMPECHE IS
PRODUCING NLY FLOW OVER THE W CARIBBEAN W OF 80W.  ANOTHER UPPER
LEVEL HIGH IS CENTERED E OF THE WINDWARD ISLANDS NEAR 15N52W. IN
BETWEEN... THERE IS A TROUGH THAT EXTENDS FROM HISPANIOLA TO
PANAMA. A TROPICAL WAVE WILL AFFECT THE WINDWARD ISLANDS TUE.
SEE ABOVE.

THE ATLANTIC OCEAN...
ALOFT...A TROUGH/RIDGE/TROUGH PATTERN COVERS THE FORECAST AREA
ALOFT. AN UPPER TROUGH IS OVER THE W ATLANTIC N OF 20N BETWEEN
60W-80W. AN UPPER LEVEL HIGH IS OVER THE CENTRAL ATLANTIC NEAR
27N43W. ANOTHER LARGE UPPER LEVEL HIGH IS CENTERED OVER THE
TROPICAL ATLANTIC NEAR 15N52W. A TROUGH IS OVER THE E ATLANTIC N
OF 20N AND E OF 30W. AT THE SURFACE...A 1021 HIGH IS CENTERED
OVER THE W ATLANTIC NEAR 29N74W. A 1016 MB LOW IS FURTHER E OVER
THE W ATLANTIC NEAR 28N63W. A SURFACE TROUGH EXTENDS SW FROM THE
LOW TO NEAR 25N68W. WIDELY SCATTERED MODERATE CONVECTION IS
WITHIN 150 NM AHEAD OF THE LOW/TROUGH. A 1023 MB HIGH WITH FAIR
WEATHER IS OVER THE CENTRAL ATLANTIC NEAR 27N47W. IT WILL REMAIN
STATIONARY DURING THE NEXT 24 HOURS WHILE THE LOW IS EXPECTED TO
DISSIPATE. THE 18/21 UTC SAHARAN AIR LAYER FROM CIMSS SHOWS
AFRICAN DUST COVERING A GOOD PORTION OF THE E-CENTRAL TROPICAL
ATLC. THE LEADING EDGE IS REACHING 45W.

$$
GR





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