Prognostic Meteorological Discussion
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FXCA20 KWBC 041815
PMDCA

TROPICAL DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
215 PM EDT TUE AUG 04 2015

DISCUSSION FROM AUG 04/12 UTC: BROAD MID/UPPER LEVEL RIDGE OVER
NORTHERN MEXICO/SOUTHWEST USA IS PROVIDING THE STEERING FLOW TO A
TUTT LOW ACROSS SOUTHWEST MEXICO. THROUGH THIS EVENING THE LOW IS
TO RELOCATE SOUTH OF THE BAJA PENINSULA. MEANWHILE...THIS IS TO
ENHANCE CONVECTION ACROSS SOUTHWEST MEXICO WHERE WE EXPECT
RAINFALL AMOUNTS OF 10-15MM/DAY AND MAXIMA OF 20-35MM. OTHER
CONVECTION IS TO CLUSTER ALONG THE SIERRA MADRE OCCIDENTAL...
WHERE WE EXPECT RAINFALL AMOUNTS OF 05-10MM/DAY AND MAXIMA OF
15MM. THROUGH WEDNESDAY THE MAXIMA INCREASES TO 15-30MM.

ANOTHER TUTT TO THE EAST DOMINATES THE FLOW ACROSS THE WESTERN
CARIBBEAN-CENTRAL AMERICA. A BUILDING RIDGE OVER THE BASIN PUSHES
THIS TROUGH WEST ACROSS CENTRAL AMERICA TO THE SOUTHERN STATES OF
MEXICO THROUGH THURSDAY MORNING. THIS TROUGH REFLECTS WELL AT MID
LEVELS OF THE ATMOSPHERE... SUSTAINING AN INVERTED TROUGH OVER THE
WESTERN CARIBBEAN-CUBA EARLY IN THE CYCLE. THIS IS TO ALSO
RELOCATE WEST ACROSS THE YUCATAN/NORTHERN CENTRAL AMERICA TO THE
SOUTHERN STATES OF MEXICO THROUGH WEDNESDAY EVENING/THURSDAY
MORNING. EARLY IN THE CYCLE THIS IS TO ENHANCE CONVECTION ACROSS
CUBA AND THE BAHAMAS TO FAVOR RAINFALL AMOUNTS OF 05-10MM/DAY AND
MAXIMA OF 15MM. AS IT RETROGRESSES ACROSS CENTRAL AMERICA THE TUTT
IS TO INITIALLY ENHANCE CONVECTION ACROSS NICARAGUA/NORTHEAST
HONDURAS WHERE WE EXPECT RAINFALL AMOUNTS OF 05-10MM/DAY AND
MAXIMA OF 15-25MM THROUGH WEDNESDAY MORNING. OVER
BELIZE-YUCATAN/GUATEMALA THIS IS TO THEN FAVOR RAINFALL AMOUNTS OF
10-15MM/DAY AND MAXIMA OF 20-35MM ON WEDNESDAY. ON THE SOUTHERN
STATES OF MEXICO EXPECTING MODERATE RAINFALL AMOUNTS WITH
ACCUMULATION OF 05-10MM/DAY AND MAXIMA OF 15-20MM DURING THE DAY
ON THURSDAY...WITH HIGHER AMOUNTS TO THEN AFFECT THE SOUTHWEST
STATES ON THURSDAY-FRIDAY...WHEN WE EXPECT RAINFALL AMOUNTS OF
10-15MM/DAY AND MAXIMA OF 20-45MM.

ON ITS WAKE...A MID/UPPER LEVEL RIDGE BUILDS ACROSS THE CARIBBEAN
BASIN TO CENTRAL AMERICA-NORTHERN SOUTH AMERICA. AS IT BUILDS
ACROSS THE BASIN THIS IS TO GRADUALLY STRENGTHEN THE TRADE WINDS
CAP. AT LOW LEVELS THIS SUSTAINS A BROAD RIDGE ACROSS THE
CENTRAL-WESTERN ATLANTIC TO THE NORTHERN CARIBBEAN. THE ENSUING
GRADIENT OVER THE BASIN FAVORS BRISK EASTERLY WINDS ACROSS THE
ISLAND CHAIN TO THE CENTRAL CARIBBEAN. THIS IS TO PERSIST THROUGH
MIDMORNING ON WEDNESDAY...WITH GRADIENT TO THEN GRADUALLY SLACKEN
AS THE WEEK WEARS ON. ON THURSDAY TO FRIDAY THE STRONGEST WINDS
ARE TO CONFINE TO THE CENTRAL CARIBBEAN WHERE THE WINDS ARE TO
PEAK AT 20-25KT. OTHERWISE WINDS OF 10-15KT ARE TO PREVAIL. EARLY
IN THE PERIOD THE BRISK EASTERLY TRADES ARE TO FAVOR GENERATION OF
STREAMERS ACROSS THE LESSER ANTILLES...BUT AS THE WINDS WEAKEN
THESE ARE TO WANE. SEA/LAND BREEZES ARE TO THEN BECOME ACTIVE
ACROSS THE LARGER ISLANDS.

BROAD TUTT OVER THE CENTRAL ATLANTIC IS TO SLOWLY RETROGRESS TO
THE WEST-SOUTHWEST...MOVING TO THE NORTH-NORTHEAST OF THE LESSER
ANTILLES LATER ON THURSDAY. AS IT RETROGRESSES IT IS TO MERGE WITH
AN UPPER LEVEL TROUGH NORTH OF THE ISLANDS. AT MID LEVELS THIS IS
TO INITIALLY FAVOR A BROAD CYCLONIC CIRCULATION OVER THE CENTRAL
ATLANTIC. THROUGH THURSDAY THIS WEAKENS TO AN OPEN TROUGH AS IT
MOVES TOWARDS THE EASTERN CARIBBEAN ISLANDS. LATER IN THE WEEK
THIS SETTLES OVER THE NORTHEAST CARIBBEAN ISLANDS...TO FAVOR AN
INCREASE IN DIURNAL CONVECTION PATTERN AS IT INTERACTS WITH SEA
BREEZE CONVERGENCE OVER THE ISLANDS DURING THE DAY ON SATURDAY.

THE ATLANTIC ITCZ LIES ACROSS THE TROPICAL ATLANTIC TO THE
SOUTHERN WINDWARD ISLANDS...WHERE IT IS TO FAVOR LIGHT TO MODERATE
CONVECTION OVER THE NEXT FEW DAYS...WITH RAINFALL AMOUNTS OF
05-10MM/DAY AND MAXIMA OF 15MM. AS IT REMAINS NORTH OF THE
GUIANAS...IN THIS AREA SEA BREEZE CONVERGENCE IS TO FAVOR RAINFALL
AMOUNTS OF 05-10MM/DAY AND MAXIMA OF 15MM. OVER VENEZUELA NET
RELATED CONVECTION IS TO FAVOR RAINFALL AMOUNTS OF 05-10MM/DAY AND
MAXIMA OF 15MM. HIGHER AMOUNTS ARE EXPECTED OVER NORTHWEST
VENEZUELA TODAY...WITH RAINFALL AMOUNTS OF 10-15MM/DAY AND MAXIMA
OF 20-45MM. ACROSS WESTERN COLOMBIA...MEANWHILE...EXPECTING
RAINFALL AMOUNTS OF 05-10MM/DAY AND MAXIMA OF 15-20MM. MOST
INTENSE...HOWEVER...IS EXPECTED TO THE SOUTHWEST WHERE THE MAXIMA
IS TO PEAK AT 20-30MM.

TROPICAL/EASTERLY WAVES INITIALIZED AT 12UTC
INITIAL  24     36     48     60     72     84     96        TYPE
46W      48W    51W    53W    56W    59W    62W    64W       TUTT
INDCD.
55W      57W    59W    62W    64W    66W    69W    71W       TW
78W      81W    DISSIPATES                                   TUTT
INDCD.

THE RETROGRESSING TUTT OVER THE CENTRAL ATLANTIC SUSTAINS AN
INDUCED/INVERTED TROUGH IN THE EASTERLY TRADES. THIS MOVES ACROSS
THE ISLAND CHAIN TO THE EASTERN CARIBBEAN EARLY ON FRIDAY
MORNING...WHERE WE EXPECT RAINFALL AMOUNTS OF 00-05MM/DAY AND
MAXIMA OF 10MM. LOCALLY HIGHER AMOUNTS OVER THE WINDWARDS ARE TO
PEAK AT 10-15MM.

A WEAK TROPICAL WAVE ALONG 55W REMAINS ON THE CONVERGENT SIDE OF
THE RETROGRESSING TUTT LOW AND A RIDGE TO THE WEST. AS IT PULLS
ACROSS THE GUIANAS THIS IS TO FAVOR RAINFALL AMOUNTS OF
05-10MM/DAY AND MAXIMA OF 15MM THROUGH WEDNESDAY MORNING...WHILE
OVER THE ISLAND CHAIN IT IS TO RESULT IN RAINFALL AMOUNTS OF
00-05MM/DAY AND MAXIMA OF 10MM. HIGHER AMOUNTS...HOWEVER...ARE
EXPECTED ACROSS THE WINDWARD ISLES WHERE THE MAXIMA IS TO PEAK AT
10-15MM. OVER THE VIRGIN ISLES-PUERTO RICO TO EASTERN HISPANIOLA
THIS IS TO THEN FAVOR RAINFALL AMOUNTS OF 00-05MM/DAY AND WIDELY
ISOLATED MAXIMA OF 10MM. OVER VENEZUELA...IN INTERACTION WITH THE
NET...EXPECTING RAINFALL AMOUNTS OF 10-15MM/DAY AND MAXIMA OF
20-35MM.

THE TUTT OVER THE WESTERN CARIBBEAN SUSTAINS AN INDUCED/INVERTED
TROUGH IN THE EASTERLY TRADES ALONG 78W. BUT THIS IS TO GRADUALLY
DISSIPATE THROUGH WEDNESDAY MORNING. MEANWHILE...AS IT MOVES TO
EASTERN NICARAGUA/NORTHEAST HONDURAS EXPECT RAINFALL AMOUNTS OF
05-10MM/DAY AND MAXIMA OF 15-25MM.

SALMON...MS (ANTIGUA AND BARBUDA)
CABRERA...ONAMET (THE DOMINICAN REPUBLIC)
DAVISON...WPC (USA)
$$




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