[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 282355
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT MON JUL 28 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 MOVING OFF THE WEST COAST OF AFRICA WITH A
1009 MB LOW LOCATED NEAR 10N14W. THIS LOW SHOWS SOME SIGNS OF
ORGANIZATION. SOME SLOW DEVELOPMENT OF THIS SYSTEM IS POSSIBLE
OVER THE NEXT COUPLE OF DAYS AS THE WAVE MOVES TO THE WNW AT
ABOUT 15 MPH. SATELLITE IMAGERY SHOWS THE CLOUD PATTERN
EXHIBITING CYCLONIC CIRCULATION DUE TO THE PRESENCE OF THE LOW
PRES. THIS WAVE WILL BE ADDED TO THE 00Z SFC MAP.

A HIGH AMPLITUDE TROPICAL WAVE EXTENDS FROM 20N40W TO 5N43W
MOVING WEST ABOUT 20 KT. INVERTED-V LOW LEVEL SIGNATURE IS
OBSERVED ON SATELLITE IMAGERY WITH MAINLY LOW/MID CLOUDS. NO
DEEP CONVECTIVE PRECIPITATION ACCOMPANIES THIS FEATURE. THIS
WAVE WILL ENTER THE TROPICAL N ATLC WATERS ON WED.

A TROPICAL WAVE HAS ENTERED THE E CARIBBEAN. ITS AXIS EXTENDS
FROM THE N LEEWARD ISLANDS TO NE VENEZUELA ALONG 62W MOVING WEST
NEAR 20 KT. THE SAHARAN AIR LAYER FROM CIMSS SHOWS AN AREA OF
AFRICAN DUST JUST BEHIND THE WAVE AXIS. SCATTERED MODERATE
CONVECTION IS FROM 11N-15N BETWEEN 60W-64W. THIS ACTIVITY IS
AFFECTING THE WINDWARD ISLANDS. MOISTURE ASSOCIATED WITH THIS
TROPICAL WAVE WILL REMAIN SOUTH OF PUERTO RICO/HISPANIOLA.

A TROPICAL WAVE IS MOVING WWD ACROSS THE YUCATAN PENINSULA AND
NORTHERN CENTRAL AMERICA GENERATING SOME SHOWER ACTIVITY. THIS
WAVE CONTINUES TO THE E PACIFIC.

...THE ITCZ...
THE ITCZ AXIS IS CENTERED ALONG 9N15W 10N29W 14N39W 9N50W
12N60W. BESIDES THE CONVECTION MENTIONED IN THE TROPICAL WAVE
SECTION...SCATTERED MODERATE CONVECTION IS NEAR 9N26W...AND FROM
6N-8N BETWEEN 48W-52W.

...DISCUSSION...

THE GULF OF MEXICO...
SHOWER AND THUNDERSTORM ACTIVITY OVER THE NORTH-CENTRAL GULF OF
MEXICO IS ASSOCIATED WITH A WEAK SURFACE TROUGH OF LOW PRESSURE
THAT RUNS FROM 31N88W TO 25N90W. UPPER-LEVEL WINDS ARE FORECAST
TO BE UNFAVORABLE FOR SIGNIFICANT DEVELOPMENT OF THIS SYSTEM AS
IT MOVES SLOWLY NORTH-NORTHWESTWARD OVER THE NEXT DAY OR TWO...
LEAVING A HIGH PRES RIDGE ACROSS THE CENTRAL GULF. SCATTERED
MODERATE CONVECTION IS FROM 26N-29N BETWEEN 87W-90W. A DIFFLUENT
PATTERN ALOFT ASSOCIATED WITH AN UPPER-LEVEL HIGH LOCATED OVER
THE N-CENTRAL GULF WATERS IS ENHANCING THIS ACTIVITY. THIS
UPPER-LEVEL FEATURE DOMINATES THE ENTIRE GULF AND THE STATE OF
FLORIDA WHERE IS ALSO ASSISTING IN THE DEVELOPMENT OF SHOWERS
AND TSTMS. A WEAK 1015 MB HIGH REMAINS OVER THE W GULF OF MEXICO
NEAR 27N93W PRODUCING MOSTLY FAIR WEATHER W OF 90W. MAINLY LIGHT
AND VARIABLE WINDS ARE NOTED THROUGHOUT THE GULF REGION.

THE CARIBBEAN SEA...
AN UPPER-LEVEL LOW IS SPINNING BETWEEN E CUBA AND JAMAICA. UPPER
DIFFLUENCE BETWEEN THIS LOW AND THE UPPER HIGH SITUATED OVER THE
GULF OF MEXICO IS HELPING TO INDUCE SCATTERED SHOWERS AND TSTMS
OVER PARTS OF CUBA...THE CAYMAN ISLANDS AND THE NW CARIBBEAN. AN
UPPER-LEVEL RIDGE WITH AXIS EXTENDING OVER NORTHERN SOUTH
AMERICA COVERS THE REMAINDER OF THE BASIN. THE COLOMBIAN OR
PANAMANIAN LOW IS GENERATING SOME SHOWER ACTIVITY OVER THE SW
CARIBBEAN WHILE A TROPICAL WAVE IS MOVING WWD ACROSS THE EASTERN
PORTION OF THE CARIBBEAN SEA. SEE TROPICAL WAVE SECTION.
MODERATE TO STRONG TRADE WINDS OF 20 TO 25 KT ARE BLOWING ACROSS
THE AREA DUE TO THE PRES GRADIENT BETWEEN THE COLOMBIAN LOW AND
THE ATLANTIC RIDGE.

THE ATLANTIC OCEAN...
THE BERMUDA-AZORES HIGH...A LARGE SUBTROPICAL SEMI-PERMANENT
CENTER OF HIGH ATMOSPHERIC PRESSURE FOUND NEAR THE AZORES IN THE
ATLC OCEAN...DOMINATES THE ATLANTIC FORECAST AREA WITH A RIDGE
EXTENDING SW TO SOUTH FLORIDA AND CUBA. A SMALL SURFACE TROUGH
IS OVER THE CENTRAL ATLANTIC AND GOES FROM 29N51W TO 24N56W.
ISOLATED SHOWERS ARE WITHIN 30 NM OF THE TROUGH AXIS. ALOFT...AN
UPPER-LEVEL TROUGH ENTERS THE REGION NEAR 31N62W THEN CONTINUES
SW TO THE UPPER-LEVEL LOW LOCATED BETWEEN E CUBA AND JAMAICA. NE
TO E WINDS W OF THE TROUGH ARE DRAWING A FAIR AMOUNT OF UPPER
LEVEL MOISTURE ACROSS THE W ATLC INTO FLORIDA AND THE BAHAMAS.
FURTHER EAST...A LARGE UPPER LEVEL HIGH IS CENTERED OVER THE
E-CENTRAL ATLANTIC NEAR 18N39W PRODUCING MODERATE TO STRONG
SUBSIDENCE. ANOTHER UPPER-LEVEL TROUGH IS OVER THE E ATLC ALONG
22W/23W WITH THE BASE OF THE TROUGH REACHING 23N. MAINLY ELY
WINDS DOMINATES THE TROPICS.

$$
GR






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