[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 101751
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT THU JUL 10 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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1715 UTC.

...SPECIAL FEATURE....

THE CENTER OF HURRICANE BERTHA AT 10/1500 UTC IS NEAR 26.5N
60.2W. BERTHA IS MOVING NORTHWEST OR 315 DEGREES AT 8 KT. THE
ESTIMATED MINIMUM CENTRAL PRESSURE IS 977 MB. THE MAXIMUM
SUSTAINED WIND SPEEDS ARE NOW 80 KT WITH GUSTS TO 100 KT KEEPING
BERTHA AS A CATEGORY 2 HURRICANE ON THE SAFFIR-SIMPSON SCALE.
BERTHA IS LOCATED ABOUT 485 MILES...785 KM...SOUTHEAST OF
BERMUDA. SWELLS ASSOCIATED WITH THIS HURRICANE ARE NOW AFFECTING
THAT ISLAND. PLEASE REFER TO THE LATEST NHC FORECAST/ADVISORY
UNDER AWIPS/WMO HEADERS MIATCMAT2/WTNT22 KNHC AND THE PUBLIC
ADVISORY UNDER MIATCPAT2/WTNT32 KNHC FOR MORE DETAILS. SATELLITE
IMAGERY INDICATES THAT THE EYE OF BERTHA HAS BECOME SOMEWHAT
RAGGED THIS MORNING...AND THE CONVECTIVE TOPS IN THE EYEWALL
HAVE WARMED. AS A RESULT...THE INITIAL INTENSITY WAS REDUCED TO
80 KT. HOWEVER...THE ATMOSPHERE IS EXPECTED TO REMAIN FAVORABLE
FOR ADDITIONAL STRENGTHENING AS A LARGE UPPER-LEVEL ANTICYCLONE
DEVELOPS OVER BERTHA DURING THE NEXT 24-48 HR. IN ADDITION...THE
SYSTEM IS STILL OVER WARM WATER. GIVEN THE ENVIRONMENT...THE
INTENSITY FORECAST CALLS FOR SLIGHT STRENGTHENING DURING THE
FIRST 24-36 HR. INTERESTS IN BERMUDA SHOULD CLOSELY MONITOR THE
PROGRESS OF BERTHA DURING THE NEXT SEVERAL DAYS.

...TROPICAL WAVES...

A TROPICAL WAVE IS ALONG 35W SOUTH OF 13N MOVING WEST 10 TO 15
KT. AN INVERTED-V PATTERN IS SEEN ON VIS SAT IMAGERY WITH A
CLUSTER OF MODERATE CONVECTION NEAR THE INTERSECTION OF THE WAVE
AXIS AND THE ITCZ. LOW-LEVEL SATELLITE DERIVED WINDS ALSO
SUPPORT THE POSITION OF THE WAVE AXIS.

THE TROPICAL WAVE THAT WAS PREVIOUSLY ANALYZED ALONG 56W ON THE
06Z SFC MAP IS RELOCATED ALONG 60W BASED ON SFC OBSERVATIONS
FROM 12Z ACROSS THE WINDWARD ISLANDS AND VIS SATELLITE PHOTOS.
CONVECTION HAS INCREASED OVER THOSE ISLANDS THIS MORNING. AT 8AM
EDT TRINIDAD REPORTED A RAINFALL AMOUNT OF 1.59 INCHES IN 24
HOURS. SCATTERED MODERATE TO ISOLATED STRONG CONVECTION IS FROM
9N TO 13N BETWEEN 58W AND 65W. A DIFFLUENT PATTERN ALOFT IS
HELPING TO INDUCE THIS SHOWER AND TSTM ACTIVITY. MOISTURE FROM
THIS WAVE IS EXPECTED TO REACH THE ABC ISLANDS LATE THIS
AFTERNOON.

...THE ITCZ...
ITCZ AXIS IS CENTERED ALONG 10N14W 7N24W 8N32W 5N40W 8N57W.
SCATTERED MODERATE CONVECTION IS FROM 3N TO 6N BETWEEN 19W AND
23W. SIMILAR CONVECTION IS NEAR 11N22W...AND NEAR 5N39W. A
CLUSTER OF MODERATE TO STRONG CONVECTION IS OVER SENEGAL AND
GUINEA BISSAU MOVING WWD.

...DISCUSSION...

THE GULF OF MEXICO...
MIDDLE TO UPPER-LEVEL RIDGE CENTERED OVER THE SE CONUS COVERS
MOST OF THE GULF REGION WHILE A WEAK CYCLONIC CIRCULATION
REMAINS OVER THE BAY OF CAMPECHE. A SFC TROUGH...PROBABLY A
REFLECTION OF THIS LOW IS ANALYZED IN THIS AREA AND LIES ALONG
24N96W 20N95W 18N92W. SCATTERED SHOWERS AND ISOLATED TSTMS ARE
ASSOCIATED WITH THESE FEATURES OVER THE SW GULF...INCLUDING THE
BAY OF CAMPECHE. THE CITY OF VERACRUZ MEXICO REPORTED THIS
MORNING 1.62 INCHES OF RAIN IN 24 HOURS. ISOLATED SHOWERS ARE
OVER THE REMAINDER OF THE GULF THANKS TO THE INFLUENCE OF THE
RIDGE. AT THE SURFACE...A WEAK RIDGE OF HIGH PRESSURE DOMINATES
THE GULF GIVING THE AREA MAINLY LIGHT TO MODERATE WINDS. THE
STRONGEST WINDS UP TO 20 KT ARE FOUND OVER THE BAY CAMPECHE DUE
A SLIGHTLY THIGH PRES GRADIENT BETWEEN THE RIDGE AND THE SFC
TROUGH.

THE CARIBBEAN SEA...
A MIDDLE TO UPPER-LEVEL TROUGH FROM THE W ATLC EXTENDS SW ACROSS
EASTERN CUBA AND THE NORTHWEST CARIBBEAN SEA GENERATING
SCATTERED SHOWERS AND TSTMS. AN UPPER-LEVEL RIDGE ANCHORED ON A
HIGH OVER NORTHERN COLOMBIA IS SOUTH OF THIS TROUGH. UPPER
DIFFLUENT ASSOCIATED WITH THIS FEATURE IS ENHANCING SCATTERED
MODERATE CONVECTION OVER THE SW CARIBBEAN. AS PREVIOUSLY
MENTIONED A TROPICAL WAVE IS AFFECTING THE WINDWARD ISLANDS AND
THE FAR SE CARIBBEAN SEA. SEE TROPICAL WAVE SECTION FOR DETAILS.
NARROW BANDS OF MAINLY LOW CLOUDS ASSOCIATED WITH THE OVERALL
CIRCULATION OF HURRICANE BERTHA ARE MOVING ACROSS THE LEEWARD
ISLANDS...THE UK/US VIRGIN ISLANDS AND PUERTO RICO. THIS
MOISTURE COUPLED WITH THE LOCAL ISLANDS EFFECTS WILL PRODUCE
ISOLATED TO SCATTERED SHOWERS AND TSTMS ACROSS THE THOSE ISLANDS
THIS AFTERNOON. THE SAN JUAN DOPPLER RADAR IS ALREADY SHOWING
SCATTERED SHOWERS OVER THESE ISLANDS AND COASTAL WATERS.
MODERATE TRADE WINDS ARE BLOWING ACROSS THE BASIN. THESE WINDS
ARE FORECAST TO INCREASE UP TO 30 KT NEAR THE COLOMBIAN COAST
BEGINNING TONIGHT THROUGH AT LEAST SUN MORNING AS PRES GRADIENT
TIGHTENS OVER THE E AND CENTRAL CARIBBEAN.

THE ATLANTIC OCEAN...
A STATIONARY MIDDLE TO UPPER LEVEL CYCLONIC CIRCULATION CENTER
IS NEAR 28N70W. CYCLONIC FLOW AROUND THIS CENTER EXTENDS SW
ACROSS THE BAHAMAS AND EASTERN CUBA. A MIDDLE TO UPPER LEVEL
TROUGH IS DROPPING SOUTHWARD JUST TO THE NORTHEAST OF HURRICANE
BERTHA...WITH AXIS CLIPPING THE FORECAST AREA NEAR 29N50W. THIS
TROUGH SUPPORTS A COLD FRONT LOCATED OVER THE CENTRAL ATLC.
OUTSIDE OF HURRICANE BERTHA...A SURFACE RIDGE DOMINATES THE
REMAINDER OF THE ATLC DISCUSSION AREA WITH A 1026 MB HIGH
CENTERED NEAR 32N27W. THIS SFC HIGH PAIRED WITH LOWER PRES OVER
WESTERN AFRICA IS PRODUCING A SWATH OF MODERATE TO STRONG NE
WINDS N OF 20N AND E OF 20W...INCLUDING THE CANARY ISLANDS. A
MIDDLE TO UPPER LEVEL TROUGH ENTERS THE THE EASTERN ATLANTIC
NEAR 32N26W THEN CONTINUES SW TO NEAR 22N35W. MID TO UPPER LEVEL
RIDGE ANCHORED ON A HIGH OVER MAINLAND AFRICA ENVELOPS THE DEEP
TROPICS PARTICULARLY E OF 50W.

$$
GR


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