Wednesday Evening Tropical Weather Discussion

AXNT20 KNHC 252342
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT WED JUN 25 2008

TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL
AMERICA...GULF OF MEXICO...CARIBBEAN SEA...NORTHERN SECTIONS OF
SOUTH AMERICA...AND 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 TROPICAL WAVE IS ALONG 50W S OF 9N MOVING W NEAR 20 KT. WEAK
INVERTED-V LOW LEVEL SIGNATURE IS SEEN ON SATELLITE IMAGERY
WHILE THE MIMIC-TPW ANIMATION CONTINUES TO SHOW A SMALL SURGE OF
MOISTURE IN THE VICINITY OF THIS WAVE. ISOLATED MODERATE
CONVECTION IS NEAR THE NORTHERN END OF THE WAVE...AND OVER ILHA
DE MARAJO IN BRAZIL.

A TROPICAL WAVE EXTENDS FROM THE CAYMAN ISLANDS TO THE SW
CARIBBEAN/PANAMA. ITS AXIS ALONG 80W S OF 20N MOVING W 15-20 KT.
THE WAVE SHOWS UP VERY WELL ON THE TOTAL PRECIPITABLE WATER
WHERE A NORTH-SOUTH MOISTURE MAXIMUM IS OBSERVED. SCATTERED
SHOWERS AND TSTMS ARE EITHER SIDE OF THE WAVE AXIS BUT MAINLY
SOUTH OF 17N. THE WAVE IS FORECAST TO MOVE ACROSS CENTRAL
AMERICA LATE TONIGHT INTO THU ENHANCING SHOWER/TSTM ACTIVITY.

...ITCZ...

ITCZ AXIS IS CENTERED ALONG 9N13W 7N25W 5N35W 5N47W INTO NE
BRAZIL. CLUSTERS OF MODERATE AND ISOLATED STRONG CONVECTION ARE
MOVING OFF THE AFRICAN COAST...LIKELY ASSOCIATED WITH THE NEXT
TROPICAL WAVE. SATELLITE IMAGERY SHOWS A BROAD AREA OF CYCLONIC
TURNING FROM 5N-10N AND E OF 20W TO THE AFRICAN COAST. THE DAKAR
VERTICAL SOUNDING IS SHOWING NW WINDS AT LOW LEVELS...INDICATING
THAT THE WAVE HAS NOT CROSS THIS AREA YET. IN SPITE OF THESE
INDICATIONS...IT IS NOT ENTIRELY CLEAR WHERE THE WAVE AXIS LIES.
FOR THAT REASON...WE WILL WAIT FOR FURTHER DATA BEFORE PLACING
THE WAVE.

...DISCUSSION...

GULF OF MEXICO...
A SHORT-WAVE TROUGH LIES OVER THE GULF STRETCHING FROM LOUISIANA
TO THE BAY OF CAMPECHE AND THE ISTHMUS OF TEHUANTEPEC. AN UPPER
LEVEL RIDGE EXTENDS FROM THE CARIBBEAN OVER THE REMAINDER OF THE
GULF REGION INTO THE W ATLC TO OVER SOUTH FLORIDA AND THE NW
BAHAMAS. SWLY FLOW BETWEEN THESE TWO UPPER LEVEL FEATURES ARE
SUPPLYING THE E GULF AND FLORIDA WITH ABUNDANCE OF TROPICAL
MOISTURE. THESE WINDS ARE ALSO ENHANCING CONVECTION OVER THE
YUCATAN PENINSULA AND WESTERN CUBA. LIGHTNING DATA REVEALS
SCATTERED TSTMS ACROSS THE YUCATAN PENINSULA AND THE STATE OF
FLORIDA. WEAK SURFACE RIDGE EXTENDS FROM THE W ATLC OVER THE
GULF WITH A 1023 MB HIGH CENTERED NEAR 29N84W. UNDER THIS
PATTERN...E TO SE WINDS OF 10 TO 15 KT ARE BLOWING ACROSS THE
GULF WITH A A NARROW BAND OF 15-20 KT OVER THE STRAITS OF
FLORIDA AND THE SE PORTION OF THE GULF. THE RIDGE WILL REMAIN IN
PLACE THE REST OF THE WORK WEEK.

CARIBBEAN...
AN UPPER RIDGE ANCHORED IN THE E PACIFIC REGION EXTENDS ACROSS
HONDURAS/NICARAGUA AND W/CENTRAL CUBA INTO THE W ATLC TO BEYOND
30N70W. A SECOND UPPER RIDGE ANCHORED E OF THE WINDWARD ISLANDS
COVERS THE E CARIBBEAN. A WEAK UPPER TROUGH REMAINS BETWEEN
THESE UPPER RIDGES EXTENDING FROM THE W ATLC INTO THE CARIBBEAN
SEA THROUGH HISPANIOLA. ABUNDANT UPPER-LEVEL MOISTURE IS BEEN
TRANSPORTED FROM NORTHERN SOUTH AMERICA INTO THE E CARIBBEAN.
UPPER DIFFLUENCE COUPLED WITH THE TROPICAL WAVE MENTIONED ABOVE
IS ENHANCING CONVECTION OVER CENTRAL AMERICA FROM W PANAMA TO
HONDURAS AS WELL AS OVER THE GULF OF HONDURAS. CONVECTION HAS
ALSO FLARED UP OVER N VENEZUELA AND COLOMBIA LIKELY DUE TO THE
PRESENCE OF THE ITCZ AXIS. MODERATE/STRONG EASTERLY TRADE WINDS
CONTINUE TO DOMINATE MOST OF THE CARIBBEAN DUE TO THE TIGHT
PRESSURE GRADIENT BETWEEN THE SURFACE RIDGE OVER THE ATLC AND
LOWER PRESSURE OVER SOUTH AMERICA.

ATLANTIC...
AN UPPER RIDGE EXTENDS FROM THE CARIBBEAN ACROSS W/CENTRAL CUBA
TO OVER THE NW BAHAMAS AND THE W ATLC W OF 70W. AN UPPER-LEVEL
LOW NEAR 28N61W HAS A TROUGH THAT EXTENDS SW AND THEN ENTERS THE
CARIBBEAN SEA THROUGH HISPANIOLA. LARGE UPPER RIDGE DOMINATES
THE REMAINDER OF THE CENTRAL ATLC ANCHORED BY AN UPPER HIGH NEAR
32N44W. AN UPPER TROUGH IS OVER THE E ATLC EXTENDING THROUGH
32N28W TO 22N47W. UPPER HIGH IS E OF THE WINDWARD ISLANDS NEAR
13N54W WITH THE RIDGE COVERING THE EASTERN CARIBBEAN TO THE
WEST. ANOTHER UPPER-LEVEL HIGH CENTERED JUST E OF THE CANARY
ISLANDS EXTENDS A RIDGE SW TO THE CAPE VERDE ISLANDS. A SURFACE
RIDGE DOMINATES THE ENTIRE ATLC FORECAST AREA ANCHORED BY A 1026
MB HIGH CENTERED NEAR 29N58W. A MOSTLY DRY AND STABLE ATMOSPHERE
IS ASSOCIATED WITH THIS RIDGE WHICH IS ALSO PRODUCING A WIDE
SWATH OF MODERATE TO STRONG ELY FLOW ACROSS THE N TROPICAL ATLC
INTO THE CARIBBEAN SEA. THIS HIGH WILL REMAIN NEARLY STATIONARY
AND SLIGHTLY WEAKEN DURING THE NEXT 24 HOURS.

$$
GR


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