THE WEATHER PREDICTION CENTER

COLLEGE PARK, MD


CARIBBEAN FORECAST DISCUSSION




TROPICAL DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
208 PM EDT TUE JUL 22 2014

AT 15UTC TD-TWO CENTERED NEAR 12.6N 48.0W...WITH MINIMUM CENTRAL
PRESSURE OF 1012 HPA AND MAXIMUM SUSTAINED WINDS OF 30KT. THE
DEPRESSION IS MOVING WEST AT 15KT. SEE NHC BULLETIN FOR DETAILS.

DISCUSSION FROM JULY 22/00UTC: AT MID/UPPER LEVELS...A TROUGH OVER
THE SOUTHEAST USA/GULF OF MEXICO SPLITS THE SUBTROPICAL RIDGE IN
TWO CELLS...WITH ONE OVER THE SOUTHWEST USA/NORTHERN MEXICO AND
THE OTHER OFF THE SOUTHEAST COAST OF THE USA. THE WESTERNMOST IS
TO CENTER DURING THE NEXT FEW DAYS ON A CLOSED HIGH OVER THE TEXAS
PANHANDLE/NORTHERN COAHUILA MEXICO...WHILE ENVELOPING AREA 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.
FURTHERMORE...AS THE RIDGE HOLDS TO THE WEST...IT IS TO INDUCE THE
SOUTHWARD AMPLIFICATION OF THE TROUGH ACROSS CENTRAL MEXICO LATER
TODAY. A LOW THEN CLOSES ALONG THE BASE OF THE TROUGH...AND UNDER
INFLUENCE OF THE RIDGE TO THE NORTH IT RETROGRESSES ACROSS THE
CENTRAL STATES OF MEXICO TO COLIMA/NAYARIT LATER ON
WEDNESDAY...WITH THE CLOSED LOW TO THEN LIFT ALONG THE PACIFIC
COAST TOWARDS SOUTHERN BAJA PENINSULA LATER ON THURSDAY. THE
INFLOW OF SHORT WAVE ENERGY AND COLD AIR ALOFT IS TO ENHANCE
CONVECTIVE INSTABILITY ACROSS SOUTHWEST MEXICO. THIS WILL COMBINE
WITH DIURNAL HEATING TO SUSTAIN AN INCREASE IN CONVECTION...WITH
MOST ACTIVE EXPECTED BETWEEN NAYARIT/COLIMA AND GUERRERO/OAXACA
LATER ON WEDNESDAY-THURSDAY...TO RESULT IN RAINFALL AMOUNTS OF
10-15MM/DAY AND MAXIMA OF 20-40MM. ACTIVITY THEN SPREADS NORTH
INTO SINALOA THROUGH FRIDAY EVENING. THE RIDGE ALOFT...AS IT
MEANDERS OVER NORTHERN MEXICO...IS TO VENT DIURNAL CONVECTION
ALONG THE SIERRA MADRE OCCIDENTAL OF MEXICO...TO FAVOR RAINFALL
AMOUNTS OF 05-10MM/DAY AND MAXIMA OF 15-20MM. THROUGH THURSDAY
EVENING THIS INCREASES TO 15-20MM/DAY AND MAXIMA OF 25-50MM AS
TUTT LOW LIFTS ALONG THE COAST.

RIDGE TO THE EAST IS TO MEANDER OFF THE COAST OF FLORIDA/THE
CAROLINAS OVER THE NEXT FEW DAYS...WHILE CENTERING ON A CLOSED
HIGH NORTH OF THE BAHAMAS. THE RIDGE ALOFT WILL PROVIDE THE
STEERING FLOW TO A TUTT OVER THE WESTERN CARIBBEAN. THE LOW
CENTERS BETWEEN CAYMAN BRAC AND EASTERN JAMAICA... EXTENDING A
TROUGH SOUTH TO PANAMA/GULF OF URABA. UNDER INFLUENCE OF THE RIDGE
TO THE WEST...THE TUTT LOW IS TO RETROGRESS ACROSS THE CAYMAN
ISLES LATER TODAY. IT THEN LIFTS ACROSS WESTERN CUBA LATER ON
WEDNESDAY/EARLY ON THURSDAY. THIS IS TO THEN GRADUALLY WEAKEN AS
THE CYCLE PROGRESSES. AS THE TUTT RETROGRESSES ACROSS JAMAICA IT
IS TO TRIGGER SCATTERED CONVECTION WITH ACCUMULATION OF
05-10MM/DAY AND MAXIMA OF 15MM. ACROSS THE CAYMAN ISLES IT IS TO
FAVOR RAINFALL AMOUNTS OF 00-05MM/DAY. AS THE UPPER LOW
RETROGRESSES ACROSS CUBA IT IS TO THEN ENHANCE DIURNAL CONVECTION
ACROSS THE ISLAND DURING THE DAY ON WEDNESDAY AND THURSDAY...TO
SUSTAIN RAINFALL AMOUNTS OF 10-15MM/DAY AND MAXIMA OF 20-30MM.

DOWNSTREAM FROM THE RIDGE...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
61W     65W    69W    74W    78W    81W    84W    87W     TW
82W     85W    88W    92W    96W   100W   104W   107W     TW

THE NHC FORECASTS TD-TWO TO WEAKEN AS IT NEARS THE LESSER ANTILLES
EARLY ON THURSDAY. THIS WILL SUSTAIN MODULATION OF THE ATLANTIC
ITCZ NORTH OF ITS CLIMATOLOGICAL POSITION. AS A RESULT...AS IT
ENTERS THE FRENCH/LEEWARD ISLES IT IS TO THEN TRIGGER SCATTERED
CONVECTION...WITH ACCUMULATION OF 10-15MM/DAY AND MAXIMA OF
20-35MM. REMNANTS OF THIS FEATURE ARE TO THEN MOVE ACROSS THE
EASTERN CARIBBEAN TO THE VIRGIN ISLES/PUERTO RICO LATER ON
THURSDAY/EARLY FRIDAY MORNING TO RESULT IN RAINFALL AMOUNTS OF
10-15MM/DAY AND MAXIMA OF 20-35MM. SIMILAR AMOUNTS ARE EXPECTED AS
IT MOVES ACROSS HISPANIOLA DURING THE DAY ON FRIDAY.

A WEAK TROPICAL WAVE ENTERED THE EASTERN CARIBBEAN EARLY THIS
MORNING...WITH AXIS NORTH ALONG 61W. IN A MID/UPPER CONVERGENT
PATTERN THIS SUSTAINS LIGHT SHALLOW CONVECTION ACROSS THE ISLAND
CHAIN TO EASTERN PUERTO RICO...WHERE IT IS TO TRIGGER RAINFALL
AMOUNTS OF 00-05MM/DAY AND MAXIMA OF 10MM. ACROSS CENTRAL
VENEZUELA IT IS TO THEN FAVOR RAINFALL AMOUNTS OF 15-20MM/DAY AND
MAXIMA OF 25-50MM AS IT INTERACTS WITH THE NEAR EQUATORIAL TROUGH.
ACROSS NORTHERN COLOMBIA-WESTERN VENEZUELA EXPECTING ACCUMULATION
OF 10-15MM/DAY AND MAXIMA OF 20-40MM...WHILE OVER HISPANIOLA
EXPECT RAINFALL AMOUNTS OF 05-10MM/DAY AND MAXIMA OF 15MM THROUGH
WEDNESDAY MORNING. AT IT PULLS ACROSS JAMAICA IT IS TO SUSTAIN
RAINFALL AMOUNTS OF 00-05MM/DAY AND MAXIMA OF 10MM. OVER SOUTHERN
CENTRAL AMERICA EXPECTING RAINFALL AMOUNTS OF 10-15MM/DAY AND
MAXIMA OF 20-40MM ON THURSDAY.

A TROPICAL WAVE ALONG 82W IS TO INTERACT WITH THE EASTERN PACIFIC
ITCZ AND TUTT LOW OVER THE CENTRAL CARIBBEAN. 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
05-10MM/DAY AND MAXIMA OF 15-20MM. ACROSS GUATEMALA TO CHIAPAS IN
SOUTHERN MEXICO IT IS TO THEN FAVOR RAINFALL AMOUNTS OF
05-10MM/DAY AND MAXIMA OF 15-30MM. ON THE SOUTHERN TO CENTRAL
STATES OF MEXICO IT IS TO SUSTAIN RAINFALL AMOUNTS OF 10-15MM/DAY
AND MAXIMA OF 20-40MM ON THURSDAY AFTERNOON.

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




Last Updated: 208 PM EDT TUE JUL 22 2014