[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 151141
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 AM EDT THU MAY 15 2008

TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL
AMERICA...THE GULF OF MEXICO...THE CARIBBEAN SEA...NORTHERN
SECTIONS OF SOUTH AMERICA...AND THE 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
1015 UTC.

...TROPICAL WAVES...

A TROPICAL WAVE IS ALONG 20W/21W S OF 12N MOVING W AT 10-15 KT.
AN AREA OF SHOWERS AND EMBEDDED TSTMS ARE ASSOCIATED WITH
THE WAVE...BUT MOST OF THIS ACTIVITY IS W OF THE WAVE AXIS. IN
ADDITION...THE MIMIC-TPW PRODUCT FROM CIMSS SHOWS THE PRESENCE
OF THIS SYSTEM WITH AN AREA OF MOISTURE EXTENDING NORTHWARD TO
NEAR 12N.

A WEAK TROPICAL WAVE IS ALONG 64W S OF 12N MOVING W AT 10 KT.
THE WAVE IS VERY ILL-DEFINED AND MOSTLY INLAND OVER CENTRAL
VENEZUELA WHERE IT IS GENERATING SCATTERED MODERATE CONVECTION
W OF WAVE AXIS. THE GFS MODEL GUIDANCE INDICATES LOW-LEVEL
MOISTURE WILL REMAIN ACROSS N CENTRAL VENEZUELA AND ADJACENT
COASTAL WATERS IN THE CARIBBEAN SEA.

...THE ITCZ...
ITCZ AXIS IS CENTERED ALONG 6N10W 5N19W 5N23W 5N28W EQ39W EQ51W.
SCATTERED MODERATE TO STRONG CONVECTION IS WITHIN 90 NM FROM A
LINE 2N9W 3N18W. SCATTERED MODERATE TO ISOLATED STRONG
CONVECTION IS FROM 6N-9N BETWEEN 14W-16W. SIMILAR CONVECTION IS
FROM 4N-8N BETWEEN 25W-28W. CLUSTERS OF SCATTERED MODERATE TO
ISOLATED STRONG CONVECTION ARE WITHIN 90-120 NM FROM A LINE
1N23W TO 3S28W.

...DISCUSSION...

GULF OF MEXICO...
THE GULF OF MEXICO LIES BETWEEN A 1020 MB SURFACE HIGH OFFSHORE
OF THE SOUTH CAROLINA IN THE W ATLC AND LOW PRESSURE TROUGHING
OVER
E TEXAS AND E MEXICO. THIS WEATHER PATTERN IS PRODUCING FAIRLY
UNIFORM 15-20 KT SOUTHERLY WINDS ACROSS THE GULF. PRE-FRONTAL
TROUGH EXTENDS ALONG THE TEXAS COAST WHERE SCATTERED SHOWERS AND
THUNDERSTORMS ARE ONGOING IN THE NW GULF. THIS ACTIVITY WILL
CONTINUE TO MOVE NE TOWARDS THE LOUISIANA/MISSISSIPPI GULF COAST
BY MID-MORNING. ALOFT...A LARGE UPPER HIGH CENTERED OVER THE
EASTERN YUCATAN PENINSULA EXTENDS A RIDGE ACROSS THE ENTIRE GULF
WITH AXIS ALONG 85W. ITS ASSOCIATED FLOW IS TRANSPORTING
ABUNDANT UPPER LEVEL MOISTURE FROM THE EPAC THROUGH MEXICO INTO
SE TEXAS AND MUCH OF THE GULF. GIVEN DIFFLUENT UPPER LEVEL
PATTERN ACROSS THE NW GULF INCREASED PRECIPITATION CHANCES ARE
EXPECTED AHEAD OF THE NEXT COLD FRONT WHICH IS FORECAST TO ENTER
THE GULF ON THURSDAY AFTERNOON.

CARIBBEAN SEA...
THE TAIL END OF A COLD FRONT EXTENDING FROM THE CENTRAL ATLC
IS PRODUCING SOME SCATTERED SHOWER ACTIVITY ACROSS E JAMAICA AND
HISPANIOLA. OTHERWISE...VERY TRANQUIL WEATHER RESIDES ACROSS THE
CARIBBEAN BASIN IN LARGE PART DUE TO A LARGE MID-UPPER RIDGE
CENTERED OVER THE EASTERN YUCATAN PENINSULA AND UPPER TROUGHING
OVER THE E CARIBBEAN. THESE UPPER FEATURES ARE PRODUCING
MODERATE TO STRONG SUBSIDENCE ACROSS THE CARIBBEAN SEA
SUPPRESSING THE DEVELOPMENT OF ANY SIGNIFICANT CONVECTION. THE
GFS MODEL GUIDANCE KEEPS MOISTURE FROM THE TAIL END OF THE FRONT
AFFECTING HISPANIOLA AND PUERTO RICO THROUGH FRI.

ATLANTIC OCEAN...
A 1001 MB LOW PRESSURE SYSTEM IS WELL N OF THE AREA OVER
THE N CENTRAL ATLC. THE ASSOCIATED COLD FRONT ENTERS THE FORECAST
AREA NEAR 32N53W THEN CONTINUES SW CROSSING TO NE OF HISPANIOLA.
LOW-LEVEL CONVERGENCE ALONG THE FRONTAL BOUNDARY COUPLED WITH
UPPER DIFFLUENT FLOW IS PRODUCING A 120-150 NM WIDE BAND OF
SCATTERED SHOWERS AND THUNDERSTORMS IMMEDIATELY E OF THE FRONT N
OF 25N. SOUTH OF 25N TO HISPANIOLA SCATTERED SHOWERS WILL
CONTINUE TO LINGER IN ASSOCIATION WITH WEAKENING FRONTAL BOUNDARY
AND ARE FORECAST ACROSS THE E DOMINICAN REPUBLIC AND PUERTO RICO
THURSDAY. COLD AIR STRATOCUMULUS CLOUDS ARE BEHIND THE FRONT
ACROSS THE W ATLC AND IMPLY THAT A COOL AND DRIER AIR MASS HAS
TAKEN HOLD ACROSS THE BAHAMAS. THE REST OF THE CENTRAL AND E
ATLC IS DOMINATED BY A 1025 MB SURFACE HIGH LOCATED NEAR 31N40W.
IN THE UPPER LEVELS...BROAD RIDGING SUPPORTS CENTRAL ATLC
SURFACE HIGH WITH AXIS EXTENDING ALONG 40W. BROAD TROUGHING WITH
BASE NEAR THE CANARY ISLANDS WILL CONTINUE TO MOVE EASTWARD AND
PROVIDE ONLY MID-UPPER LEVEL CLOUDINESS ALONG THE COAST OF
MOROCCO.

OF NOTE...TODAY MARKS THE BEGINNING OF THE EASTERN PACIFIC
HURRICANE SEASON. BASED ON LATEST AVERAGES...EVERY YEAR 15 NAMED
STORMS FORM...9 OF WHICH BECOME HURRICANES AND 4 OF THOSE
HURRICANES WOULD BE OF CATEGORY 3 OR GREATER IN STRENGTH ON THE
SAFFIR-SIMPSON SCALE. THE ATLANTIC HURRICANE SEASON BEGINS JUNE
1ST WITH BOTH ATLANTIC AND EASTERN PACIFIC TROPICAL SEASONS
ENDING NOVEMBER 30TH.

$$
HUFFMAN




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