Tuesday Evening Tropical Weather Discussion

AXNT20 KNHC 172346
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT TUE JUN 17 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
2300 UTC.

...TROPICAL WAVES...

A TROPICAL WAVE IS ALONG 37W S OF 17N MOVING W NEAR 15-20 KT.
SATELLITE IMAGERY DEPICTS A WELL DEFINED INVERTED-V SIGNATURE.
ABUNDANT LOW TO MID LEVEL CYCLONIC TURNING IS APPARENT ALONG THE
AXIS BETWEEN 8N-14N. SCATTERED MODERATE CONVECTION IS WITHIN 90
NM OF THE WAVE AXIS BETWEEN 8N-11N. 850 MB RELATIVE VORTICITY
SUPPORTS THE WAVE POSITION.

A TROPICAL WAVE IS ALONG 54W S OF 15N MOVING W NEAR 20 KT. A LOW
AMPLITUDE INVERTED-V CLOUD PATTERN IS APPARENT ALONG THE AXIS
S OF 9N. MIMIC-TPW SHOWS A SLIGHT BULGE OF MOISTURE N OF
SURINAME AND FRENCH GUIANA...HOWEVER NO SIGNIFICANT CONVECTION
IS ASSOCIATED WITH THE WAVE.

A TROPICAL WAVE IS ALONG 88W...OR ALONG THE EAST COAST OF THE
YUCATAN PENINSULA...S OF 22N MOVING W AT 10-15 KT. THE WAVE IS
EMBEDDED IN AN AREA OF DEEP LAYERED MOISTURE...THUS THE POSITION
IS FAIRLY UNCERTAIN. A SMALL CLUSTER OF MODERATE TO STRONG
CONVECTION IS FROM 13N-15N BETWEEN 87W-89W.

...ITCZ...

THE ITCZ AXIS IS CENTERED ALONG 10N13W 5N25W 8N40W 7N53W.
SCATTERED MODERATE CONVECTION IS WITHIN 120 NM N OF THE AXIS
BETWEEN 18W-21W. SIMILAR CONVECTION IS WITHIN 120 NM S OF THE
AXIS BETWEEN 22W-25W. SCATTERED MODERATE/ISOLATED STRONG
CONVECTION IS FROM 8N-13N FROM 57W TO OVER SOUTH AMERICA.

...DISCUSSION...

GULF OF MEXICO...
AN UPPER-LEVEL TROUGH EXTENDS ACROSS THE GULF REGION THIS
AFTERNOON WITH ITS AXIS STRETCHING FROM THE FLORIDA BIG BEND TO
THE SOUTHERN BAY OF CAMPECHE. A DIFFLUENT PATTERN BETWEEN THE
LEADING EDGE OF THE TROUGH AND AN UPPER-LEVEL HIGH OVER THE
CARIBBEAN IS GENERATING A WIDE AREA OF SHOWERS AND THUNDERSTORMS
ACROSS THE FLORIDA STRAIGHTS AND INTO THE W ATLC. ADDITIONAL
SHOWERS AND ISOLATED THUNDERSTORMS ARE MOVING INTO THE FAR
NORTHERN GULF AHEAD OF A FRONTAL BOUNDARY OVER THE SOUTHERN
CONUS. AT THE SFC...A WEAK TROUGH EXTENDS ACROSS CENTRAL
FLORIDA...SUPPORTING CONVECTION ALONG THE EAST COAST OF FLORIDA.
THE REMAINDER OF THE GULF IS RATHER TRANQUIL UNDER THE INFLUENCE
OF A WEAK SFC HIGH ANCHORED IN THE NW GULF NEAR 26N93W. THE WEAK
PRESSURE GRADIENT AROUND THE HIGH IS PRODUCING LIGHT WINDS
ACROSS THE BASIN. EXPECT THE COLD FRONT CURRENTLY OVER THE
SOUTHERN CONUS TO MOVE INTO THE NORTHERN GULF WATERS DURING THE
NEXT 24-48 HOURS.

CARIBBEAN...
A BROAD UPPER-LEVEL RIDGE AROUND A HIGH NEAR 15N81W DOMINATES
THE WEATHER PATTERN IN THE CARIBBEAN. DIVERGENCE ALOFT BETWEEN
THIS RIDGE AND THE AFOREMENTIONED TROUGH OVER THE GULF IS
GENERATING A WIDE SWATH OF SHOWERS AND THUNDERSTORMS ACROSS THE
NW GULF...THE CAYMAN ISLANDS...AND WESTERN CUBA. STRONG
SUBSIDENCE ALONG THE SE PORTION OF THE RIDGE IS KEEPING THE
CENTRAL AND EASTERN CARIBBEAN MOSTLY CLEAR WITH ONLY PATCHY LOW
CLOUDS MOVING THROUGH THE AREA. A BUILDING HIGH PRESSURE IN THE
ATLANTIC IS INCREASING TRADE WIND FLOW THROUGH THE CARIBBEAN TO
20-25 KT...WITH UP TO 30 KT ALONG THE COLOMBIAN COAST. THE
STRONG ONSHORE FLOW IS GENERATING A LINE OF SHOWERS AND
THUNDERSTORMS ALONG THE EAST COAST OF NICARAGUA.

ATLANTIC...
A BROAD AREA OF SHOWERS AND THUNDERSTORMS FILLS THE W ATLC
EXTENDING FROM THE EAST COAST OF FLORIDA...OVER THE BAHAMAS...TO
64W...MOSTLY BETWEEN 25N-30N. THIS CONVECTIVE ACTIVITY IS DRIVEN
BY UPPER-LEVEL DIVERGENCE BETWEEN A TROUGH OVER THE GULF OF
MEXICO AND A RIDGE OVER THE CARIBBEAN SEA. A COLD FRONT IS
EXPECTED TO MOVE OFF THE EAST COAST OF THE CONUS LATE TONIGHT
BRINGING ADDITIONAL CONVECTION TO THE AREA. MOSTLY ZONAL UPPER
FLOW DOMINATES THE WEST AND CENTRAL ATLC WITH A SHORTWAVE TROUGH
NEAR 59W N OF 21N. A DEEP LAYERED TROUGH COVERS THE EAST ATLC.
THIS TROUGH IS REFLECTED AT THE SFC BY DISSIPATING COLD FRONT
THAT STRETCHES ACROSS THE AZORES TO 31N40W WHERE IT CONTINUES AS
A SFC TROUGH ALONG 28N45W TO 24N54W. A BAND OF MULTI-LAYERED
CLOUDS AND SCATTERED SHOWERS EXTENDS UP TO 120 NM AHEAD OF THE
TROUGH. THIS TROUGH SPLITS A PAIR OF SFC HIGH PRESSURE SYSTEMS.
THE STRONGER OF THE TWO...A 1024 MB HIGH...IS CENTERED NEAR
30N34W AND IS EXPECTED TO REMAIN STATIONARY. THE SECOND HIGH IS
CENTERED FURTHER WEST NEAR 29N50W. THE PRESSURE GRADIENT BETWEEN
THIS STRONGER HIGH AND LOWER PRES OVER AFRICA WILL CONTINUE TO
PRODUCE MODERATE NLY WINDS MAINLY N OF 18N AND E OF 25W.

$$
WADDINGTON


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