Prognostic Meteorological Discussion
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FXCA20 KWBC 031813
PMDCA

TROPICAL DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
213 PM EDT MON AUG 03 2015

DISCUSSION FROM AUG 03/12 UTC: PERSISTENT MID/UPPER LEVEL RIDGE
OVER THE SOUTHWEST USA/NORTHERN STATES OF MEXICO IS DRIVING A TUTT
LOW WEST ALONG THE SOUTH COAST OF MEXICO INTO THE EASTERN PACIFIC.
THROUGH THIS EVENING THE TROUGH IS TO PULL ACROSS THE SOUTHWEST
STATES OF MEXICO...AND RELOCATE SOUTH OF THE BAJA PENINSULA LATER
ON TUESDAY. MEANWHILE...EXPECT CONVECTIVE ENHANCEMENT ON THE
SOUTHWEST STATES OF MEXICO TO RESULT IN RAINFALL AMOUNTS OF
10-15MM/DAY AND MAXIMA OF 20-45MM. THIS THEN DECREASES TO
05-10MM/DAY AND MAXIMA OF 15-20MM ON WEDNESDAY. OVER NORTHWEST
MEXICO...ALONG THE SIERRA MADRE...EXPECTING RAINFALL AMOUNTS OF
05-10MM/DAY AND MAXIMA OF 15-20MM. THROUGH WEDNESDAY THIS
INCREASES TO 05-10MM/DAY AND MAXIMA OF 15-30MM.

A BROAD TUTT TO THE EAST DOMINATES THE FLOW ACROSS THE
CENTRAL/WESTERN CARIBBEAN. THE TROUGH IS CUT OFF FROM THE
FLOW...AND AS SUCH IT IS EXPECTED TO GRADUALLY WEAKEN AS IT
MIGRATES WEST.  THROUGH TUESDAY EVENING THE WANING TROUGH MOVES TO
THE NORTHWEST CARIBBEAN/YUCATAN PENINSULA...AND THROUGH WEDNESDAY
AFTERNOON IT MOVES ACROSS GUATEMALA TO THE SOUTHERN STATES OF
MEXICO. 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. MOST ACTIVE CONVECTION...HOWEVER...IS EXPECTED TO
THE SOUTH. EARLY IN THE CYCLE THIS IS TO ENHANCE CONVECTION ALONG
THE ITCZ OVER PANAMA-COSTA RICA...WITH RAINFALL AMOUNTS OF
05-10MM/DAY AND MAXIMA OF 15-20MM. ACTIVITY IS TO THEN BUILD NORTH
AND WEST ACROSS NICARAGUA/NORTHEAST HONDURAS WHERE WE EXPECT
RAINFALL AMOUNTS OF 05-10MM/DAY AND MAXIMA OF 15-25MM ON MONDAY TO
TUESDAY. OVER BELIZE-YUCATAN/GUATEMALA THIS IS TO THEN FAVOR
RAINFALL AMOUNTS OF 10-15MM/DAY AND MAXIMA OF 20-35MM ON TUESDAY
TO WEDNESDAY.

A BUILDING MID/UPPER LEVEL RIDGE IS TO THEN BECOME THE DOMINANT
SYNOPTIC SCALE FEATURE ACROSS THE CENTRAL/EASTERN CARIBBEAN. AT
250 HPA THIS IS TO INITIALLY CENTER ON A CLOSED HIGH NEAR 20S 42W.
THROUGH WEDNESDAY EVENING THE HIGH WILL MOVE WEST TO THE DOMINICAN
REPUBLIC. LIKEWISE...AT 500 HPA...A RIDGE IS TO GRADUALLY BUILD
WEST-SOUTHWEST ACROSS THE GREATER ANTILLES TO THE CENTRAL
CARIBBEAN. AS IT BUILDS...THIS IS TO STRENGTHEN THE TRADE WINDS
CAP WHILE SUSTAINING THE RAPID EROSION OF AVAILABLE MOISTURE. THE
STRONG CAP INVERSION IS TO HOLD THROUGH WEDNESDAY MORNING. AT LOW
LEVELS THIS IS TO SUSTAIN A BROAD RIDGE ACROSS THE CENTRAL-WESTERN
ATLANTIC. THIS...IN-TURN...IS TO TIGHTEN THE PRESSURE GRADIENT
ACROSS THE EASTERN-CENTRAL CARIBBEAN EARLY IN THE CYCLE...TO FAVOR
BRISK EASTERLY TRADES ACROSS THE ISLAND CHAIN TO THE CENTRAL
CARIBBEAN. BUT LATER ON WEDNESDAY THE GRADIENT STARTS TO
SLACKEN...AND THE TRADES WEAKEN ACROSS THE ISLAND CHAIN/EASTERN
CARIBBEAN. THIS PATTERN IS TO PERSIST THROUGH THE END OF THE
WEEK...WHEN WINDS DECREASE TO 05-10KT. MEANWHILE...EXPECTING FAIR
WEATHER CONDITIONS TO PREVAIL ACROSS HISPANIOLA-PUERTO
RICO-LEEWARD AND THE FRENCH ISLES.

THE ATLANTIC ITCZ IS TO REMAIN NORTH OF THE GUIANAS INTO
VENEZUELA-COLOMBIA. DIURNAL CONVECTION ACROSS THE GUIANAS IS TO
THEN RESULT IN RAINFALL AMOUNTS OF 05-10MM/DAY...WHILE OVER
VENEZUELA-EASTERN COLOMBIA EXPECTING RAINFALL AMOUNTS OF
05-10MM/DAY AND MAXIMA OF 15-20MM. ACROSS WESTERN COLOMBIA EXPECT
RAINFALL AMOUNTS OF 10-15MM/DAY AND MAXIMA OF 20-30MM. THROUGH
THURSDAY-FRIDAY EXPECTING AN INCREASE IN DIURNAL CONVECTION AS THE
SURGING TRADES OVER THE BASIN START TO SLACKEN AND SEA BREEZE
PATTERN STRENGTHENS.

TROPICAL/EASTERLY WAVES INITIALIZED AT 12UTC
INITIAL  24     36     48     60     72     84     96        TYPE
40W      43W    46W    48W    51W    54W    57W    60W    TUTT
INDCD.
52W      53W    55W    58W    61W    64W    66W   DISSIPATES  TW
73W      76W    78W    81W    83W    86W    88W   DISSIPATES TUTT
INDCD.

A TUTT LOW OVER THE CENTRAL ATLANTIC SUSTAINS AN INDUCED/INVERTED
TROUGH ALONG 40W. THE TUTT ALOFT IS TO RETROGRESS TO THE NORTHEAST
CARIBBEAN EARLY ON THURSDAY MORNING...WITH LOW LEVEL PERTURBATION
TO THEN ENTER THE ISLANDS LATER IN THE DAY. AS IT ENTERS THE
ISLAND CHAIN THIS IS TO FAVOR SCATTERED CONVECTION WITH RAINFALL
AMOUNTS OF 00-05MM/DAY AND MAXIMA OF 10MM.

A WEAK TROPICAL WAVE EXTENDS ALONG 52W TO 25N. THIS IS TO REMAIN
ON THE CONVERGENT SIDE OF THE RETROGRESSING TUTT LOW...AND AS A
RESULT IT IS EXPECTED TO GRADUALLY WEAKEN/NEARLY DISSIPATE LATER
ON THURSDAY. AS IT PULLS ACROSS THE GUIANAS THIS IS TO FAVOR
RAINFALL AMOUNTS OF 05-10MM/DAY AND MAXIMA OF 15-20MM ON
MONDAY-TUESDAY...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.

TUTT OVER THE WESTERN CARIBBEAN SUSTAINS AN INDUCED/INVERTED
TROUGH IN THE EASTERLY TRADES ALONG 73W. THIS IS ALSO FORECAST TO
WEAKEN LATER IN THE CYCLE AS IT MOVES ACROSS CENTRAL AMERICA TO
SOUTHERN STATES OF MEXICO. EARLY IN THE CYCLE THIS IS TO ENHANCE
CONVECTION ACROSS NORTHERN COLOMBIA TO FAVOR RAINFALL AMOUNTS OF
10-15MM/DAY AND MAXIMA OF 20-30MM. ACROSS HAITI-EASTERN
CUBA-JAMAICA IT IS TO FAVOR RAINFALL AMOUNTS OF 00-05MM/DAY AND
MAXIMA OF 10MM. ON TUESDAY FOCUS OF THE CONVECTION SHIFTS TO
EASTERN NICARAGUA-NORTHEAST HONDURAS WHERE IT IS TO FAVOR RAINFALL
AMOUNTS OF 05-10MM/DAY AND MAXIMA OF 15-25MM. OVER HONDURAS-EL
SALVADOR TO GUATEMALA IT IS TO THEN FAVOR RAINFALL AMOUNTS OF
05-10MM/DAY AND MAXIMA OF 15-20MM.

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




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