Monday Evening Tropical Weather Discussion

AXNT20 KNHC 302339
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT MON JUN 30 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 38W S OF 13N MOVING W 10-15 KT.
POSITION BASED ON EXTRAPOLATION AND ALL SIGNIFICANT CONVECTION
REMAINS EMBEDDED WITHIN THE ITCZ.

A TROPICAL WAVE IS ALONG 49W S OF 14N MOVING W 10-15 KT. A
LOW-AMPLITUDE INVERTED-V CURVATURE IS OBSERVED ON SATELLITE
IMAGERY. A SMALL CLUSTER OF MODERATE CONVECTION IS WITHIN 60 NM
W OF THE AXIS FROM 10N-11N.

A TROPICAL WAVE IS OVER VENEZUELA ALONG 65W S OF 14N MOVING W
NEAR 15 KT. NEARBY SFC OBSERVATIONS INDICATE FALLING PRESSURE
IN ADVANCE OF THE WAVE. NO SIGNIFICANT CONVECTION IS ASSOCIATED
WITH THIS WAVE.

A TROPICAL WAVE IS IN THE WESTERN CARIBBEAN ALONG 81W S OF 20N
MOVING W 15-20 KT. SFC OBSERVATIONS DISPLAY THE EXPECTED E-SE
WIND SHIFT BEHIND THE WAVE. NO SIGNIFICANT CONVECTION IS
ASSOCIATED WITH THIS WAVE.

...ITCZ...
THE ITCZ AXIS IS CENTERED ALONG 6N10W 7N20W 7N30W 8N40W 10N50W
AND INTO S AMERICA NEAR 10N60W. SCATTERED MODERATE CONVECTION IS
WITHIN 60 NM EITHER SIDE OF THE AXIS BETWEEN 13W AND 23W.
CLUSTERS OF MODERATE CONVECTION ARE FROM 5N-10N BETWEEN 33W-41W.
SCATTERED MODERATE CONVECTION IS WITHIN 150 NM N OF THE AXIS W
OF 52W.

...DISCUSSION...

GULF OF MEXICO...
A DEEP-LAYERED TROUGH OVER THE EASTERN CONUS EXTENDS A COLD
FRONT ALONG THE SOUTHERN GULF STATES...JUST NORTH OF THE
DISCUSSION AREA. A PRE-FRONTAL TROUGH LIES ACROSS THE NE GULF
FROM NEAR PANAMA CITY FLORIDA TO NEAR 8N89W. SCATTERED SHOWERS
AND THUNDERSTORMS FILL THE GULF N OF 25N IN ADVANCE OF THE
FRONTAL BOUNDARY. ALOFT...INSTABILITY AND DIVERGENCE ALONG A
SHORTWAVE TROUGH IS GENERATING AN AREA OF SCATTERED SHOWERS AND
THUNDERSTORMS IN THE WESTERN BAY OF CAMPECHE. THE REMAINDER OF
THE GULF IS FREE OF SIGNIFICANT CONVECTION DUE TO AN UPPER RIDGE
THAT STRETCHES ACROSS THE YUCATAN PENINSULA...FLORIDA
STRAIGHTS...AND INTO THE W ATLC. EXPECT THE FRONTAL BOUNDARY TO
MOVE INTO THE NE GULF LATE TONIGHT BEFORE DISSIPATING LATE TUE.
THE ATLC SFC RIDGE WILL REBUILD OVER THE GULF THROUGH FRI.

CARIBBEAN...
ANTICYCLONIC FLOW FROM AN UPPER RIDGE OVER THE YUCATAN PENINSULA
COVERS THE CARIBBEAN W OF 80W. THE FLOW CROSSES 80W AND FEEDS
INTO THE UPPER LEVEL TROUGH THAT EXTENDS FROM THE ATLANTIC OCEAN
OVER HISPANIOLA TO NEAR 14N76W. DIVERGENCE BETWEEN THESE
FEATURES IS FUELING CONVECTION FROM 15N-19N BETWEEN 77W-85W.
THIS DIVERGENCE HAS ALSO PROVIDED NEEDED LIFT TO SUPPORT
CONVECTION INITIATED BY ONSHORE FLOW ALONG COASTAL
HONDURAS/NICARAGUA. SCATTERED SHOWERS/ISOLATED THUNDERSTORMS
HAVE FLARED UP IN THE SW CARIBBEAN ALONG THE COAST OF PANAMA IN
RESPONSE TO LOW-LEVEL WIND SPEED CONVERGENCE. DAYTIME HEATING
HAS ONCE AGAIN INDUCED ISOLATED THUNDERSTORMS OVER THE NRN
CARIBBEAN ISLANDS. THE CENTRAL CARIBBEAN REMAINS RELATIVELY
CLEAR UNDER A DRY AND STABLE AIR MASS ALONG THE BASE OF THE
UPPER TROUGH. SWLY UPPER FLOW ALONG THE LEADING EDGE OF THE
TROUGH IS ADVECTING A DEEP MOISTURE LAYER ACROSS THE EASTERN
CARIBBEAN AND MAY BE GENERATING ISOLATED SHOWERS OVER THE
LEEWARD ISLANDS. AT THE SFC...A STRONG RIDGE OVER THE ATLC
CONTINUES TO PROVIDE A TIGHT PRESSURE GRADIENT ACROSS THE
BASIN...PRODUCING STRONG EASTERLY TRADES THROUGHOUT.

ATLANTIC...
A STRONG HIGH PRESSURE RIDGE...ANCHORED BY A 1027 MB HIGH SW OF
THE AZORES...CONTINUES TO DOMINATE THE ATLANTIC PRODUCING
MODERATE EASTERLY FLOW THROUGHOUT THE REGION. THE ONLY AREA OF
ACTIVE CONVECTION LIES IN THE W ATLC WHERE A SQUALL LINE HAS
MOVED OUT AHEAD OF AN APPROACHING COLD FRONT AND...AS OF
21Z...IS AFFECTING CENTRAL FLORIDA AND THE COASTAL WATERS W OF
79W N OF 28N. ADDITIONAL CLUSTERS OF SCATTERED SHOWERS AND
THUNDERSTORMS ARE W OF 72W EXTENDING FROM THE BAHAMAS TO NORTH
OF THE DISCUSSION AREA. THIS ACTIVITY IS BEING GENERATED BY THE
APPROACHING FRONTAL BOUNDARY AND IS ENHANCED BY UPPER LEVEL
DIVERGENCE AHEAD OF THE DEEP-LAYERED TROUGH OVER THE EASTERN
CONUS. ALOFT...DIVERGENCE ALONG THE SRN EXTENT OF AN UPPER-HIGH
NEAR 16N46W IS ENHANCING CONVECTION ALONG THE ITCZ.

$$
WADDINGTON


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