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Tropical Discussion
 
(Caution: Version displayed is not the latest version. - Issued 1816Z Jul 21, 2014)
 
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TROPICAL DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
216 PM EDT MON JUL 21 2014

DISCUSSION FROM JULY 21/00UTC: A MID/UPPER LEVEL TROUGH OVER THE
SOUTHEAST USA/GULF OF MEXICO SPLITS THE SUBTROPICAL RIDGE IN TWO
CELLS. THE WESTERNMOST IS TO CENTER ON A CLOSED HIGH OVER THE
TEXAS PANHANDLE/NORTHERN COAHUILA MEXICO...AS IT IS TO EXTEND OVER
THE CONTINENT TO THE NORTH OF 20N. THE
EASTERNMOST...MEANWHILE...IS TO CENTER ON A CLOSED HIGH JUST NORTH
OF THE BAHAMAS...AND IT IS TO EXPAND ACROSS THE WESTERN ATLANTIC
WHILE ALSO CONFINING TO AREA NORTH OF 20N. THE RIDGE ALOFT IS TO
VENT DIURNAL CONVECTION ALONG THE SIERRA MADRE OCCIDENTAL OF
MEXICO...TO FAVOR RAINFALL AMOUNTS OF 10-15MM/DAY AND MAXIMA OF
20-30MM.

FURTHERMORE...AS THE RIDGE HOLDS TO THE WEST...IT IS TO INDUCE THE
SOUTHWARD AMPLIFICATION OF THE TUTT ACROSS THE CAMPECHE SOUND TO
SOUTHERN STATES OF MEXICO LATER ON TUESDAY. THIS IS TO THEN SHEAR
A CLOSED LOW THAT RETROGRESSES ACROSS THE CENTRAL STATES OF MEXICO
TO THE EASTERN TROPICAL PACIFIC LATER ON WEDNESDAY. INFLOW OF
SHORT WAVE ENERGY ALOFT IS TO ENHANCE CONVECTIVE INSTABILITY
ACROSS SOUTHWEST MEXICO...WITH GRADUAL SURGE IN CONVECTION
EXPECTED BETWEEN NAYARIT/COLIMA AND GUERRERO/OAXACA LATER ON
WEDNESDAY...TO RESULT IN RAINFALL AMOUNTS OF 10-15MM/DAY AND
MAXIMA OF 20-45MM.

A WANING TUTT LOW MEANDERS TO THE SOUTH/SOUTHWEST OF
NAYARIT-COLIMA MEXICO. UNDER INFLUENCE OF THE BROAD RIDGE TO THE
NORTH THIS LOW IS TO RETROGRESS ACROSS THE EASTERN PACIFIC. EARLY
IN THE CYCLE...HOWEVER...THE TROUGH ALOFT IS TO ENHANCE CONVECTIVE
DEVELOPMENT OVER SOUTHWEST MEXICO...TO SUSTAIN RAINFALL AMOUNTS OF
05-10MM/DAY AND MAXIMA OF 15-20MM.

ALSO...UNDER INFLUENCE OF THE RIDGE TO THE EAST...ENVIRONMENTAL
CONDITIONS OVER THE BAHAMAS ARE TO REMAIN FAVORABLE AND CONDUCIVE
TO DEEP CONVECTION. AT LOW LEVELS...AN INDUCED/INVERTED TROUGH
EXTENDS NORTH ACROSS CUBA TO THE BAHAMAS...ENHANCING LOW LEVEL
CONVERGENCE WHILE FAVORING RAINFALL AMOUNTS OF 15-20MM/DAY AND
MAXIMA OF 35-70MM. THROUGH TUESDAY EVENING...RAINFALL MAXIMA OVER
CUBA WILL DECREASE TO 25-50MM...WHILE ACROSS THE BAHAMAS EXPECTING
ACCUMULATION OF 10-15MM/DAY AND MAXIMA OF 20-30MM.
FURTHERMORE...THE RIDGE ALOFT WILL PROVIDE THE STEERING FLOW TO A
TUTT OVER THE CARIBBEAN. THE LOW LIES TO THE SOUTH OF
JAMAICA...AND UNDER INFLUENCE OF THE RIDGE TO THE WEST IT IS TO
RETROGRESS ACROSS THE CAYMAN ISLES THROUGH TUESDAY EVENING...INTO
CUBA LATER ON WEDNESDAY. EARLY IN THE CYCLE THE TROUGH IS TO
ENHANCE CONVECTIVE DEVELOPMENT ACROSS JAMAICA-HISPANIOLA TO FAVOR
RAINFALL AMOUNTS OF 05-10MM/DAY AND MAXIMA OF 15MM. AS THE UPPER
LOW RETROGRESSES ACROSS CUBA IT IS TO THEN ENHANCE DIURNAL
CONVECTION ACROSS THE ISLAND DURING THE DAY ON WEDNESDAY...TO
SUSTAIN RAINFALL AMOUNTS OF 10-15MM/DAY AND MAXIMA OF 20-30MM.
ALSO...AS THE TUTT MEANDERS OVER THE CENTRAL CARIBBEAN IT IS TO
INTERACT WITH THE NEAR EQUATORIAL TROUGH OVER COLOMBIA. THIS IS TO
ENHANCE CONVECTIVE DEVELOPMENT TO RESULT IN RAINFALL AMOUNTS OF
15-20MM/DAY AND MAXIMA OF 25-50MM.

ANOTHER TUTT LIES OVER THE ATLANTIC TO THE NORTH OF PUERTO
RICO/LEEWARD ISLANDS. THIS SEPARATES THE RIDGE OVER THE WESTERN
ATLANTIC FROM A CELL OVER THE CENTRAL ATLANTIC. UPPER TROUGH IS TO
REMAIN BETWEEN 67W-60W AND TO THE NORTH OF 20N. ASSOCIATED MID
LEVEL FEATURE IS TO ALSO REMAIN NORTH OF THE ISLANDS AS THE CYCLE
PROGRESSES...LIMITING ITS WEATHER IMPACT TO OPEN WATERS OF THE
ATLANTIC...WITH LITTLE TO NO ENHANCEMENT EXPECTED OVER THE
NORTHEAST CARIBBEAN ISLES.

TROPICAL/EASTERLY WAVES INITIALIZED AT 12UTC
INITIAL  24     36     48     60     72     84     96     TYPE
43W     46W    48W    51W    54W    57W    60W    63W     TW
55W     57W    60W    64W    68W    72W    76W    79W     TW
76W     79W    82W    86W    89W    92W    96W   100W     TW

THE NHC IS MONITORING PERTURBATION IN THE EASTERLY TRADES ALONG
43W AND ITS ASSOCIATED CYCLONIC CIRCULATION. ALTHOUGH SOME
INTENSIFICATION IS POSSIBLE...THE NHC EXPECTS SYSTEM TO WEAKEN TO
AN OPEN WAVE AS IT NEARS THE GUIANAS. IN INTERACTION WITH THE ITCZ
THIS IS TO THEN SUSTAIN RAINFALL AMOUNTS OF 10-15MM/DAY AND MAXIMA
OF 20-30MM. OVER THE WINDWARD ISLES/NORTHEAST VENEZUELA IT IS TO
THEN FAVOR RAINFALL AMOUNTS OF 10-15MM/DAY AND MAXIMA OF 20-30MM.
ACROSS THE LEEWARD/FRENCH ISLES EXPECTING ACCUMULATION OF
05-10MM/DAY AND MAXIMA OF 15-25MM...WITH LOCALLY HIGHER AS IT
REACHES PUERTO RICO LATER THIS WEEK.

A WEAK TROPICAL WAVE IS INITIALIZED ALONG 55W. MOST ACTIVE
CONVECTION WITH THIS FEATURE IS EXPECTED ALONG THE ITCZ OVER
NORTHERN GUYANA/NORTHEAST VENEZUELA...WITH RAINFALL AMOUNTS OF
05-10MM/DAY AND MAXIMA OF 15-20MM. ACROSS CENTRAL VENEZUELA IT IS
TO THEN FAVOR RAINFALL AMOUNTS OF 05-10MM/DAY AND MAXIMA OF
15-20MM...WHILE OVER PUERTO RICO AND THE USVI IT IS TO RESULT IN
RAINFALL AMOUNTS OF 00-05MM/DAY AND MAXIMA OF 10MM. ACROSS
NORTHERN COLOMBIA-WESTERN VENEZUELA EXPECTING ACCUMULATION OF
15-20MM/DAY AND MAXIMA OF 25-50MM.

A TROPICAL WAVE ALONG 76W IS TO INTERACT WITH THE PANAMANIAN LOW
AND THE NEAR EQUATORIAL TROUGH OVER COLOMBIA-PANAMA...TO SUSTAIN
RAINFALL AMOUNTS OF 15-20MM/DAY AND MAXIMA OF 25-50MM. ACROSS
PANAMA TO COSTA RICA AND EASTERN NICARAGUA IT IS TO ALSO FAVOR
RAINFALL AMOUNTS OF 15-20MM/DAY AND MAXIMA OF 25-50MM. OVER
WESTERN NICARAGUA/EL SALVADOR IT IS TO THEN FAVOR RAINFALL AMOUNTS
OF 10-15MM/DAY AND MAXIMA OF 20-30MM. ACROSS GUATEMALA TO CHIAPAS
IN SOUTHERN MEXICO IT IS TO THEN FAVOR RAINFALL AMOUNTS OF
10-15MM/DAY AND MAXIMA OF 20-35MM. ON THE SOUTHERN TO CENTRAL
STATES OF MEXICO IT IS TO THEN SUSTAIN RAINFALL AMOUNTS OF
15-20MM/DAY AND MAXIMA OF 25-50MM ON THURSDAY AFTERNOON.

FIGUEROA...MARN (EL SALVADOR)
VALVERDE...IMN (COSTA RICA)
DAVISON...WPC (USA)