[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 171034
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 AM 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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1115 UTC.

...TROPICAL WAVES...

TROPICAL WAVE IS ALONG 34W S OF 12N MOVING W NEAR 15-20 KT. A
WELL DEFINED LOW/MID LEVEL CYCLONIC CIRCULATION REMAINS ALONG
THE WAVE NEAR 8N. LOW LEVEL SATELLITE DERIVED WINDS AND 850 MB
VORTICITY SUPPORT THE POSITION OF THE WAVE AXIS. SCATTERED
MODERATE CONVECTION IS MAINLY WITHIN 140 NM W OF THE WAVE AXIS
FROM 7N-11N. MOISTURE FROM THIS TROPICAL WAVE IS FORECAST BY THE
COMPUTER MODELS TO REACH THE LESSER ANTILLES ON THU.

A WEAK TROPICAL WAVE IS ALONG 50W S OF 15N MOVING W NEAR 20 KT.
THE WAVE SHOWS SOME INVERTED-V CLOUD PATTERN AND CONVECTION IS
CONFINED TO THE ITCZ. THE SAHARAN AIR LAYER FROM CIMSS INDICATES
THAT THE WAVE IS AT THE LEADING EDGE OF A EXTENSIVE AREA OF
AFRICAN DUST.

TROPICAL WAVE IS OVER CENTRAL AMERICA ALONG 85W/86W S OF 21N
MOVING W AT 10-15 KT. THE WAVE IS EMBEDDED IN AN AREA OF DEEP
LAYERED MOISTURE AS DEPICTED ON THE TPW PRODUCT. THIS FEATURE IS
ONLY GENERATING ISOLATED SHOWERS AND TSTMS OVER HONDURAS AND
NICARAGUA.

...ITCZ...

THE ITCZ AXIS IS CENTERED ALONG 9N13W 6N22W 7N31W 6N41W 7N59W.
SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS WITHIN 120 NM N
OF AXIS E OF 22W TO THE AFRICAN COAST. SIMILAR CONVECTION IS
FOUND WITHIN 130 NM N OF AXIS BETWEEN 50W-58W. CLUSTERS OF
SCATTERED MODERATE CONVECTION ARE NEAR 7N37W...AND NEAR 6N40W.

...DISCUSSION...

GULF OF MEXICO...
AN UPPER-LEVEL TROUGH EXTENDS FROM N FLORIDA TO THE SW PORTION
OF THE GULF WHILE A BROAD UPPER RIDGE REMAINS ANCHORED OVER
NORTH/CENTRAL MEXICO COVERING THE NW CORNER OF THE GULF WITH
MODERATE TO STRONG SUBSIDENCE. SW UPPER LEVEL WINDS AHEAD OF THE
TROUGH ARE HELPING TO INDUCE SCATTERED SHOWERS AND TSTMS OVER SE
MEXICO AND THE GULF OF TEHUANTEPEC...AND ARE EXPECTED TO SUPPORT
CONVECTION OVER SOUTH FLORIDA THIS AFTERNOON WHERE HEAVY
RAINFALL ARE POSSIBLE...PARTICULARLY ALONG THE EAST COAST METRO
AREAS. AT THE SURFACE...A WEAK RIDGE...WITH A 1015 MB HIGH NEAR
27N92W REMAINS IN CONTROL OF THE WEATHER PATTERN ACROSS THE GULF
GIVING THE AREA MAINLY LIGHT WINDS. THE EXCEPTION IS THE WESTERN
GULF WHERE SE TO S WINDS OF 10-15 KT ARE NOTED. THE RIDGE IS
EXPECTED TO PERSIST DURING THE NEXT SEVERAL DAYS WITH A WEAK
COLD FRONT ENTERING THE NE PORTION OF THE GULF LATE WED. A
NARROW LINE OF SHOWERS WITH EMBEDDED TSTMS IS NEAR THE LOUISIANA
COAST...LIKELY DUE TO A DIFFLUENT PATTERN ALOFT. MOSTLY FAIR
WEATHER IS NOTED OVER THE REMAINDER OF THE GULF UNDER THE
INFLUENCE OF THE RIDGE.

CARIBBEAN...
A BROAD UPPER RIDGE DOMINATES THE CARIBBEAN ANCHORED ON A HIGH
LOCATED NEAR CABO GRACIAS A DIOS NICARAGUA. SWLY WINDS BETWEEN
THIS HIGH AND THE UPPER TROUGH THAT LIES ACROSS THE GULF OF
MEXICO ARE TRANSPORTING ABUNDANT UPPER LEVEL MOISTURE FROM THE
EPAC THROUGH CENTRAL AMERICA INTO THE NW CARIBBEAN...CUBA AND
THE BAHAMAS. UPPER DIFFLUENCE ASSOCIATED WITH THESE WINDS ARE
SUPPORTING THE DEVELOPMENT OF SOME CONVECTIVE ACTIVITY OVER THE
CAYMAN ISLANDS...CUBA AND THE BAHAMAS. LIGHTNING DATA REVEALS
THAT TSTMS ARE MORE CONCENTRATED OVER THE NW BAHAMAS. A TROPICAL
WAVE IS MOVING WWD OVER CENTRAL AMERICA. SEE TROPICAL WAVE
SECTION FOR DETAILS. BROAD UPPER RIDGE FROM THE TROPICAL ATLC
COVERS THE E CARIBBEAN WITH STRONG SUBSIDENCE AND DRY AIR. THE
COMBINATION OF A SFC HIGH BUILDING N OF AREA AND THE PRESENCE OF
THE COLOMBIAN LOW IS PRODUCING STRONG TRADE WINDS OF 20-30 KT
ACROSS THE CENTRAL CARIBBEAN.

ATLANTIC...
NEARLY ZONAL FLOW DOMINATES THE W AND CENTRAL ATLC WITH A PAIR
OF SHORT-WAVE TROUGH ALONG 67W/68W N OF 22N...AND ALONG OF 55W N
OF 27N. A DEEP LAYERED TROUGH LOCATED N OF AREA SUPPORTS A COLD
FRONT THAT CLIPS THE FORECAST REGION NEAR 31N40W THEN CONTINUES
AS A TROUGH TO 25N50W. SCATTERED SHOWERS ARE ASSOCIATED WITH THE
TROUGH. AN UPPER-LEVEL LOW IS OVER THE E ATLC NEAR 28N22W. A
TROUGH EXTENDS FROM THIS LOW INTO THE TROPICS NEAR 14N30W. BROAD
UPPER E/W RIDGE DOMINATES THE TROPICS S OF 20N AND WEST OF 35W
TO OVER THE E CARIBBEAN. A BROAD BUT WEAK SURFACE RIDGE COVERS
THE ENTIRE FORECAST AREA WITH A COUPLE OF HIGH CENTERS. ONE OF
1021 MB IS NEAR 28N51W. THE SECOND ONE IS NEAR 30N34W WITH 1024
MB. THIS SYSTEM WILL REMAIN NEARLY STATIONARY DURING THE NEXT 24
HOURS. PRES GRADIENT BETWEEN THIS HIGH AND LOWER PRES OVER
AFRICA WILL CONTINUE TO PRODUCE MODERATE TO FRESH NLY WINDS
MAINLY N OF 18N AND E OF 25W.

$$
GR/CW






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