Prognostic Meteorological Discussion
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FXCA20 KWBC 301829
PMDCA

TROPICAL DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
228 PM EDT TUE AUG 30 2016

AT 15 UTC TD NINE CENTERED NEAR 24.0N 87.2W...WITH MAXIMUM
SUSTAINED WINDS OF 30KT AND MINIMAL CENTRAL PRESSURE OF 1004 HPA.
THE TD IS MOVING WEST-NORTHWEST AT 06KT. SEE NHC BULLETIN FOR
OFFICIAL FORECAST.

TROPICAL DISCUSSION FROM AUG 30/12UTC: A SHORT WAVE TROUGH/TUTT
OVER THE WESTERN GULF OF MEXICO SPLITS THE SUBTROPICAL RIDGE IN
TWO CELLS...WITH THE WESTERNMOST EXTENDING OVER MEXICO WHILE THE
EASTERNMOST EXTENDS OVER FLORIDA-BAHAMAS-CUBA-NORTHWEST CARIBBEAN
TO THE YUCATAN. ALTHOUGH RIDGE PATTERN ALOFT IS TO PERSIST...THE
TUTT IS FORECAST TO GRADUALLY FILL THROUGH THURSDAY EVENING.
MEANWHILE...THE RIDGE ALOFT IS TO VENT DIURNAL CONVECTION ACROSS
CENTRAL-WESTERN MEXICO. OVER SONORA-SINALOA EXPECTING RAINFALL
AMOUNTS OF 10-15MM/DAY AND MAXIMA OF 20-30MM THROUGH WEDNESDAY
EVENING. ON THURSDAY THROUGH FRIDAY THIS WILL DECREASE TO
05-10MM/DAY AND MAXIMA OF 15-20MM. OVER SOUTHWEST MEXICO/SIERRA
MADRE DEL SUR EXPECTING RAINFALL AMOUNTS OF 05-10MM/DAY AND MAXIMA
OF 15MM. THROUGH THURSDAY THIS WILL INCREASE TO MAXIMA OF 20-35MM.
OVER NORTHEAST MEXICO...THE TROUGH ALOFT WILL FAVOR CONVECTION
BETWEEN COAHUILA AND TAMAULIPAS...WITH RAINFALL AMOUNTS OF
05-10MM/DAY AND MAXIMA OF 15MM THROUGH THURSDAY EVENING.

THE RIDGE ALOFT IS ALSO VENTING CONVECTION IN ASSOCIATION WITH TD
NINE. THE NHC IS FORECASTING THIS DEPRESSION TO GRADUALLY
STRENGTHEN TO A TROPICAL STORM WHILE LIFTING TO THE NORTHEAST.
MEANWHILE...THIS WILL ENHANCE MOISTURE CONVERGENCE ACROSS
WESTERN-CENTRAL CUBA...WHERE IT IS TO FAVOR RAINFALL AMOUNTS OF
25-50MM/DAY AND MAXIMA OF 75-125MM. IN THIS AREA STORM TOTAL
AMOUNTS COULD PEAK AT 400-500MM. OTHER CONVECTION IS EXPECTED
ACROSS THE NORTHWEST BAHAMAS...WHERE THE MOIST INFLOW IS TO FAVOR
RAINFALL AMOUNTS OF 10-15MM/DAY AND MAXIMA OF 20-45MM THROUGH
WEDNESDAY MORNING...DECREASING TO 05-10MM/DAY AND MAXIMA OF 15MM
ON WEDNESDAY. THE DEPRESSION ALSO FAVORS AN INDUCED INVERTED
TROUGH ACROSS THE WESTERN CARIBBEAN TO BELIZE/QUINTANA ROO IN THE
YUCATAN. THE INVERTED TROUGH IS ENHANCING LOW LEVEL MOISTURE
CONVERGENCE TO FAVOR RAINFALL AMOUNTS OF 10-15MM/DAY AND MAXIMA OF
20-45MM. ON WEDNESDAY...AS THE STORM MIGRATES TO THE
NORTHEAST...THIS WILL DECREASE TO 05-10MM/DAY AND MAXIMA OF
15-25MM IN A DIURNAL PATTERN.

FARTHER EAST...A TUTT LOW NORTH OF THE DOMINICAN REPUBLIC EXTENDS
A TROUGH SOUTH TO THE EASTERN CARIBBEAN. AT 500 HPA A HIGH NEAR
25N 60W IS BUILDING A RIDGE TO THE EASTERN CARIBBEAN. THE BUILDING
RIDGE WILL SUSTAIN A STRONG TRADE WINDS CAP ACROSS THE EASTERN
CARIBBEAN ISLANDS. ALSO...AS THE RIDGE BUILDS ACROSS THE NORTHERN
CARIBBEAN...THE MID LEVEL LOW IS TO DECOUPLE FROM THE UPPER LEVEL
CIRCULATION. THROUGH THURSDAY THE MID LEVEL TROUGH IS FORECAST TO
FILL WHILE MEANDERING TO THE NORTH-NORTHEAST. THE UPPER LEVEL
TROUGH IS TO MEANWHILE REMAIN NEARLY STATIONARY THROUGH WEDNESDAY
EVENING. ON THURSDAY...AS THE MID LEVEL VORTEX FILLS...THE UPPER
TROUGH IS TO THEN MIGRATE WEST INTO THE BAHAMAS-EASTERN
CUBA/JAMAICA-CENTRAL CARIBBEAN. MOST ACTIVE CONVECTION WITH THIS
FEATURE IS EXPECTED IN ASSOCIATION WITH THE MID LEVEL LOW AS IT
MEANDERS NORTH OF THE ISLANDS. THROUGH THURSDAY MORNING THIS IS TO
WEAKEN. ACROSS HISPANIOLA-EASTERN CUBA-JAMAICA THIS IS TO HAVE
LITTLE TO NO INFLUENCE IN LOCAL CONVECTION...AS THE MID LEVEL
RIDGE IS EXPECTED TO STRENGTHEN THE TRADE WINDS CAP.

AT LOW LEVELS THE BUILDING MID LEVEL RIDGE WILL SUSTAIN A RIDGE
OVER THE WESTERN ATLANTIC TO THE NORTHERN CARIBBEAN. THIS RIDGE
SUSTAINS A FAIRLY TIGHT GRADIENT ACROSS THE BASIN...WITH EASTERLY
TRADES OF 30-35KT EXPECTED OVER THE SOUTHERN CARIBBEAN/OFF THE
COAST OF COLOMBIA. ACROSS THE NORTHERN CARIBBEAN THE WINDS ARE TO
PEAK AT 20-25KT. THIS WILL FAVOR GENERATION OF STREAMERS ACROSS
THE LEEWARD/VIRGIN ISLES...TO AFFECT EASTERN PORTIONS OF PUERTO
RICO FROM TIME-TO-TIME. BUT THIS IS TO ONLY FAVOR LIGHT RAINFALL
AMOUNTS...WITH ACCUMULATION OF 00-05MM/DAY. ACROSS JAMAICA THE
SURGING TRADES WILL FAVOR SCATTERED CONVECTION OVER THE NEXT TWO
DAYS...WITH ACCUMULATION OF 05-10MM/DAY AND MAXIMA OF 15-25MM.

ITCZ CONVERGENCE ACROSS SOUTHERN CENTRAL AMERICA IS TO FAVOR
RAINFALL AMOUNTS OF 10-15MM/DAY AND MAXIMA OF 20-35MM. ALONG THE
NEAR EQUATORIAL TROUGH OVER CENTRAL VENEZUELA AND AMAZONIA IN
EASTERN COLOMBIA EXPECTING RAINFALL AMOUNTS OF 05-10MM/DAY AND
MAXIMA OF 15-20MM. THROUGH THURSDAY THE MAXIMA WILL INCREASE TO
15-30MM IN SCATTERED CONVECTION. ALSO...A SURGING FRONT OVER
BRASIL/PREFRONTAL SHEAR LINE ARE TO FAVOR AN INCREASE IN
CONVECTION ACROSS AMAZONIA IN VENEZUELA-SOUTHERN COLOMBIA AND THE
PIEDEMONTE LLANERO IN COLOMBIA...WITH RAINFALL AMOUNTS OF
15-20MM/DAY AND MAXIMA OF 30-60MM. BUT AS THE FRONT WANES ON
WEDNESDAY THIS WILL DECREASE TO 10-15MM/DAY AND MAXIMA OF 20-35MM.
OTHER CONVECTION IS TO CLUSTER ACROSS THE WESTERN PLAIN/ANDEAN
REGION OF COLOMBIA...WHERE LOW LEVEL WESTERLY WINDS ARE TO FAVOR
TOPOGRAPHICALLY INDUCED CONVECTION. IN THIS AREA EXPECTING
MODERATE RAINFALL AMOUNTS WITH ACCUMULATION OF 10-15MM/DAY AND
MAXIMA OF 20-35MM....WITH LOCALLY HIGHER AMOUNTS LIKELY DUE TO
STRONG TOPOGRAPHICAL FORCING.

TROPICAL/EASTERLY WAVES INITIALIZED AT 12UTC

INITIAL    24      36      48      60      72      84      96
TYPE
47W       50W     53W     56W     59W     62W     66W      70W
TW
90W       91W     92W     93W     94W     96W     98W     100W
EW
100W     102W    104W    106W    108W    110W    111W     112W
EW

A TROPICAL WAVE IS INITIALIZED ALONG 47W. INITIALLY...MOST ACTIVE
CONVECTION WITH THIS FEATURE IS TO CONFINE TO THE ATLANTIC ITCZ.
AS IT ENTERS THE ISLAND CHAIN LATER ON THURSDAY THIS IS TO TRIGGER
ISOLATED CONVECTION WITH RAINFALL AMOUNTS OF 00-05MM/DAY AND
MAXIMA OF 10MM. HIGHER AMOUNTS ARE EXPECTED TO THE SOUTH AS IT
INTERACTS WITH THE ITCZ OVER NORTHEAST VENEZUELA/SOUTHERN WINDWARD
ISLANDS...WHERE IT IS TO FAVOR RAINFALL AMOUNTS OF 05-10MM/DAY AND
MAXIMA OF 15-20MM. ON SATURDAY...ACTIVITY IS TO CLUSTER ACROSS
NORTHWEST VENEZUELA WITH ACCUMULATION OF 10-15MM/DAY AND MAXIMA OF
20-30MM.

AN EASTERLY WAVE ALONG 90W IS TO SLOWLY MOVE ACROSS SOUTHERN
GUATEMALA TO SOUTHERN CHIAPAS...REACHING SOUTHWEST MEXICO LATER ON
THURSDAY. OVER THE NEXT COUPLE OF DAYS THIS IS TO ENHANCE LATE
AFTERNOON CONVECTION ACROSS EL SALVADOR/SOUTHERN HONDURAS-SOUTHERN
GUATEMALA-SOUTHERN MEXICO...TO RESULT IN RAINFALL AMOUNTS OF
10-15MM/DAY AND MAXIMA OF 20-35MM. AS THE WAVE PULLS AWAY THIS
WILL DECREASE TO 10-15MM/DAY AND MAXIMA OF 20-30MM. ACROSS
GUERRERO-OAXACA THIS IS TO THEN FAVOR RAINFALL AMOUNTS OF
10-15MM/DAY AND MAXIMA OF 20-35MM ON WEDNESDAY TO THURSDAY.

AN EASTERLY WAVE ALONG 100W IS TO ENHANCE CONVECTION ACROSS
COLIMA-NAYARIT-GUERRERO IN SOUTHWEST MEXICO...WHERE IT IS TO FAVOR
RAINFALL AMOUNTS OF 05-10MM/DAY AND MAXIMA OF 15MM.

CASTILLO...UCR (COSTA RICA)
CONTRERAS...IMN (COSTA RICA)
GALVEZ/DAVISON...WPC (USA)
$$





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