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Tropical Discussion
 
(Caution: Version displayed is not the latest version. - Issued 1828Z Aug 27, 2014)
 
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TROPICAL DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
228 PM EDT WED AUG 27 2014

DISCUSSION FROM AUGUST 27/00UTC: AT UPPER LEVELS...AN AMPLIFYING
TROUGH OVER THE WESTERN USA CONTINUES TO PRESS AGAINST A WANING
CELL OF THE SUBTROPICAL RIDGE OVER NORTHERN MEXICO. UPPER RIDGE
PATTERN IS TO NEARLY COLLAPSE EARLY ON THURSDAY. A STRONGER CELL
OF THE RIDGE...HOWEVER...LIES TO THE EAST AND SOUTH...ENVELOPING
THE GULF OF MEXICO-CENTRAL/SOUTHERN STATES OF MEXICO AND NORTHERN
CENTRAL AMERICA. THE LATTER HAS A FAIRLY STRONG MID LEVEL
PRESENCE...WITH AXIS EXTENDING ACROSS THE GULF-SOUTHEAST USA WHILE
ANCHORING ON A CLOSED HIGH OVER FLORIDA. ALSO AT MID LEVELS...THE
TROUGH IS TO GRADUALLY PULL ACROSS THE WESTERN TO THE CENTRAL USA
THROUGH FRIDAY EVENING/EARLY SATURDAY MORNING. ON ITS WAKE...MID
LEVEL RIDGE PATTERN IS TO STRENGTHEN ACROSS THE BAJA PENINSULA AND
THE NORTHWEST STATES OF MEXICO... SUSTAINING EROSION OF AVAILABLE
MOISTURE WHILE STRENGTHENING MID LEVEL CAP INVERSION. AS A
RESULT...EXPECTING A DECREASE IN ACTIVITY ALONG THE SIERRA MADRE
OCCIDENTAL AND DEL SUR. EARLY IN THE CYCLE EXPECT ACCUMULATION OF
10-15MM/DAY AND MAXIMA OF 20-30MM. THIS DECREASES TO 05-10MM/DAY
AND MAXIMA OF 15-25MM. THE OPPOSITE IS TROUGH ALONG THE PACIFIC
COASTAL STATES OF GUERRERO-CHIAPAS...WHERE AMPLIFYING TROUGH IS TO
FAVOR AN INCREASE IN ACTIVITY. IN THIS AREA INITIALLY EXPECTING
RAINFALL AMOUNTS OF 10-15MM/DAY AND MAXIMA OF 20-30MM. THIS
INCREASES TO 15-30MM/DAY AND MAXIMA OF 40-80MM THROUGH SATURDAY
MORNING. THIS IS TO ALSO SUSTAIN COASTAL CONVECTION ACROSS
SOUTHERN GUATEMALA-EL SALVADOR/SOUTHERN HONDURAS TO NORTHWEST
NICARAGUA... WITH RAINFALL AMOUNTS OF 15-20MM/DAY AND MAXIMA OF
25-50MM. THROUGH THURSDAY THIS INCREASES TO 15-20MM/DAY AND MAXIMA
OF 35-70MM.

A NORTH-TO-SOUTH MID/UPPER LEVEL TROUGH ALONG 70W/73W TO EASTERN
CUBA SEPARATES THE RIDGE OVER THE GULF OF MEXICO FROM ANOTHER OVER
THE CENTRAL ATLANTIC. THE LATTER BOUNDS BETWEEN 70W-40W AND TO THE
NORTH OF 20N. OVER THE CENTRAL CARIBBEAN...MID/UPPER LEVEL TROUGH
PATTERN NORTH OF THE ISLANDS FAVORS AN INVERTED TROUGH ALONG 80W
TO JAMAICA/THE CAYMAN ISLES. UNDER INFLUENCE OF RIDGE OVER THE
GULF/WESTERN CARIBBEAN THE INVERTED TROUGH IS TO MEANDER WEST
ACROSS THE CENTRAL CARIBBEAN...MOVING TO NICARAGUA EARLY ON
THURSDAY AND ACROSS HONDURAS/EL SALVADOR LATER ON FRIDAY. EARLY IN
THE CYCLE THIS IS TO INTERACT WITH THE EASTERN PACIFIC ITCZ.
ACROSS WESTERN PANAMA-COSTA RICA EXPECTING RAINFALL AMOUNTS OF
15-20MM/DAY AND MAXIMA OF 30-60MM. AS THE TROUGH MEANDERS WEST
INTO NICARAGUA/NORTHEAST HONDURAS IT IS TO THEN FAVOR RAINFALL
AMOUNTS OF 10-15MM/DAY AND MAXIMA OF 20-40MM...WHILE OVER EL
SALVADOR/SOUTHERN HONDURAS EXPECTING RAINFALL AMOUNTS OF
15-30MM/DAY AND MAXIMA OF 40-80MM. AS THE TROUGH RETROGRESSES
ACROSS THE CENTRAL-WESTERN CARIBBEAN IT IS TO FAVOR AN INCREASE IN
CONVECTION ACROSS CUBA...WHERE IT IS TO SUSTAIN RAINFALL AMOUNTS
OF 15-20MM/DAY AND MAXIMA OF 25-50MM EARLY IN THE CYCLE. ACROSS
THE CAYMAN ISLES EXPECTING 05-10MM/DAY AND MAXIMA OF 15-20MM
THROUGH THURSDAY MORNING.

RETROGRESSING TUTT LOW NOW CENTERS NEAR 20N 55W. BROAD UPPER LEVEL
RIDGE OVER THE CENTRAL NORTH ATLANTIC IS TO STEER THE TUTT TO THE
WEST-NORTHWEST. THE TUTT LOW MOVES NORTH OF PUERTO RICO AND THE
VIRGIN ISLES BY MIDDAY ON THURSDAY. THE TROUGH IS TO SLOWLY
MEANDER TO THE WEST-NORTHWEST TO JUST NORTH OF THE DOMINICAN
REPUBLIC THROUGH SATURDAY MORNING. AS IT MEANDERS NORTH OF THE
FORECAST AREA...THE TUTT LOW IS TO EXTEND A SHORT WAVE TROUGH
ACROSS THE NORTHEAST CARIBBEAN ISLES. AT MID LEVELS THIS IS TO
REFLECT AS AN INVERTED TROUGH...WITH AXIS ACROSS THE VIRGIN ISLES
LATER ON THURSDAY...INTO PUERTO RICO EARLY ON FRIDAY MORNING.
LATER DURING THE DAY IT IS TO MEANDER ACROSS THE MONA PASSAGE TO
EASTERN HISPANIOLA. BEST CYCLONIC ROTATION WITH THIS FEATURE IS
EXPECTED TO THE NORTH OF 22N. RETROGRESSING TUTT IS INTERACTING
WITH THE ATLANTIC ITCZ AND TROPICAL WAVES ENTERING THE ISLAND
CHAIN IN SUPPORT OF ORGANIZED DEEP CONVECTION. THIS PATTERN IS
LIKELY TO PERSIST OVER THE NEXT FEW DAYS...SUSTAINING A GRADUAL
INCREASE IN CONVECTION ACROSS THE NORTHEAST CARIBBEAN ISLES (SEE
BELOW FOR DETAILS).

TROPICAL/EASTERLY WAVES INITIALIZED AT 12UTC
INITIAL  24     36     48     60     72     84     96     TYPE
51W     55W    57W    59W    62W    63W    65W     68W     TW
61W     65W    69W    73W    76W    80W    84W     87W     TW

A TROPICAL WAVE ALONG 51W QUICKLY MOVES ACROSS THE GUIANAS THROUGH
MIDDAY ON THURSDAY...MEANWHILE TRIGGERING RAINFALL AMOUNTS OF
00-05MM/DAY AND MAXIMA OF 10MM IN ISOLATED CONVECTION. LATER IN
THE DAY IT IS TO ENTER THE FRENCH/LEEWARD ISLES...WHERE IN
INTERACTION WITH TUTT NORTH OF THE ISLANDS IT IS TO SUSTAIN
RAINFALL AMOUNTS OF 10-15MM/DAY AND MAXIMA OF 20-40MM. THROUGH
FRIDAY EVENING/SATURDAY MORNING IT MOVES ACROSS THE VIRGIN ISLES
TO PUERTO RICO...WHERE IT IS TO SUSTAIN RAINFALL AMOUNTS OF
15-20MM/DAY AND MAXIMA 25-50MM.

PROGRESSIVE TROPICAL WAVE EXTENDS ALONG 61W. AS IT PULLS ACROSS
THE EASTERN CARIBBEAN THIS IS TO SUSTAIN A MOIST PLUME THAT GRAZES
THE CARIBBEAN COAST OF PUERTO RICO AND THE DOMINICAN REPUBLIC.
THIS IN INTERACTION WITH SEA BREEZE CONVERGENCE IS TO RESULT IN
RAINFALL AMOUNTS OF 10-15MM/DAY AND MAXIMA OF 20-35MM. HIGHER
AMOUNTS ARE EXPECTED AS THE WAVE ENTERS JAMAICA LATER ON
FRIDAY...WITH ACCUMULATION OF 15-20MM/DAY AND MAXIMA OF 25-50MM.
OVER VENEZUELA-COLOMBIA THE WAVE IS TO INTERACT WITH THE NEAR
EQUATORIAL TROUGH TO SUSTAIN RAINFALL AMOUNTS OF 10-15MM/DAY AND
MAXIMA OF 20-35MM. ACROSS THE ABC ISLES EXPECTING SCATTERED
CONVECTION WITH ACCUMULATION OF 10-15MM/DAY AND MAXIMA OF 20-30MM.
ACROSS COLOMBIA THIS INCREASES TO MAXIMA OF 20-45MM...WHILE OVER
WESTERN PANAMA/COSTA RICA-NICARAGUA IT IS TO SUSTAIN RAINFALL
AMOUNTS OF 15-20MM AND MAXIMA OF 25-50MM.

VALVERDE...IMN (COSTA RICA)
MEDINA...ONAMET (REPUBLICA DOMINICANA)
DAVISON...WPC(USA)