Prognostic Meteorological Discussion
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FXCA20 KWBC 271831
PMDCA

TROPICAL DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
230 PM EDT TUE SEP 27 2016

TROPICAL DISCUSSION FROM SEPTEMBER 27/12UTC: AT MID/UPPER
LEVELS...BUILDING CELL OF THE SUBTROPICAL RIDGE DOMINATES THE FLOW
ACROSS MEXICO-GULF AND NORTHERN CENTRAL AMERICA. AT 250 HPA THE
RIDGE IS TO CENTER ON A HIGH THAT IS TO MEANDER NEAR 22N 100W
DURING THE NEXT THREE DAYS. AS THE RIDGE INTENSIFIES...IT IS TO
DISPLACE A TROUGH TO THE WEST. THE TROUGH EXTENDS TO THE
SOUTH-SOUTHWEST ACROSS SOUTHERN ARIZONA-NORTHWEST MEXICO TO THE
EASTERN PACIFIC. THROUGH WEDNESDAY MORNING THE TROUGH WILL LIFT TO
THE NORTH-NORTHEAST. AS THE RIDGE BUILDS AND THE TROUGH PULLS AWAY
DIURNAL CONVECTION ACROSS SONORA MEXICO WILL DECREASE TO
00-05MM/DAY AND MAXIMA OF 10MM. ACROSS SINALOA EXPECTING RAINFALL
AMOUNTS OF 05-10MM/DAY AND MAXIMA OF 15-20MM THROUGH THURSDAY
MORNING. ON THE CENTRAL STATES OF MEXICO... MEANWHILE...DIURNAL
CONVECTION IS TO FAVOR RAINFALL AMOUNTS OF 10-15MM/DAY AND MAXIMA
OF 20-45MM. ON THE SOUTHERN STATES OF MEXICO-GUATEMALA AND EL
SALVADOR/HONDURAS EXPECTING RAINFALL AMOUNTS OF 05-10MM/DAY AND
MAXIMA OF 15-25MM.

EAST OF THE SUBTROPICAL RIDGE...AT 250 AND 500 HPA...A TROUGH
EXTENDS SOUTH ACROSS FLORIDA/EASTERN GULF OF MEXICO TO WESTERN
CUBA/NORTHWESTERN CARIBBEAN. AS THE RIDGE TO THE WEST BUILDS THE
TROUGH IS FORECAST TO GRADUALLY DEEPEN. THROUGH THURSDAY
EVENING/FRIDAY MORNING IT WILL REACH MAXIMUM AMPLITUDE...GRADUALLY
ENVELOPING THE WESTERN-CENTRAL CARIBBEAN. INFLOW OF SHORT WAVE
ENERGY IS TO ENHANCE DIURNAL CONVECTION ACROSS THE BAHAMAS-CUBA
AND POTENTIALLY THE CAYMAN ISLES. ACROSS THE BAHAMAS EXPECTING
RAINFALL AMOUNTS OF 05-10MM/DAY AND MAXIMA OF 15-25MM...WITH
LOCALLY HIGHER AMOUNTS LIKELY ACROSS ANDROS ISLAND AND GRAND
BAHAMA TO THE NORTH. THROUGH THURSDAY THE MAXIMA WILL DECREASE TO
15MM. ACROSS CUBA THIS WILL FAVOR SCATTERED DEEP CONVECTION WITH
ACCUMULATION OF 10-15MM/DAY AND MAXIMA OF 20-30MM. LOCALLY HIGHER
AMOUNTS ARE LIKELY ACROSS CENTRAL CUBA AND YOUTH ISLAND (ISLA DE
LA JUVENTUD). THROUGH WEDNESDAY THIS WILL DECREASE TO 05-10MM/DAY
AND MAXIMA OF 15MM. ACROSS THE CAYMAN ISLES EXPECTING RAINFALL
AMOUNTS OF 00-05MM/DAY AND MAXIMA OF 10MM.

FURTHERMORE...THE DEEPENING POLAR TROUGH OVER NORTH AMERICA WILL
THEN SUPPORT A SURFACE FRONT THAT SURGES ACROSS THE SOUTHERN USA
TO THE NORTHERN GULF/NORTHEAST STATES OF MEXICO LATER ON FRIDAY.
AS IT ENTERS TAMAULIPAS THIS WILL TRIGGER LIGHT TO MODERATE
RAINFALL AMOUNTS WITH ACCUMULATION OF 05-10MM/DAY AND MAXIMA OF
15-20MM.

A TUTT LOW TO THE NORTH OF THE DOMINICAN REPUBLIC EXTENDS A SHORT
WAVE TROUGH TO THE EASTERN CARIBBEAN. AT 250 HPA BUILDING CELL OF
THE SUBEQUATORIAL RIDGE LIES TO THE EAST...ORIGINATING ON A CLOSED
HIGH NEAR 15N 45W. THROUGH WEDNESDAY MORNING THE RIDGE IS FORECAST
TO BUILD WEST ACROSS THE ISLAND CHAIN TO THE CENTRAL CARIBBEAN. AS
THE RIDGE BUILDS...THE CLOSED HIGH IS TO RELOCATE TO THE LEEWARD
ISLANDS. THE BUILDING RIDGE WILL THEN DISPLACE THE TUTT TO THE
NORTH-NORTHEAST...WITH AXIS RAPIDLY WEAKENING AS ITS SHORT WAVE
ENERGY SHEARS TO THE NORTH. MEANWHILE...DURING THE DAY TODAY THIS
TROUGH WILL ENHANCE CONVECTION ACROSS HISPANIOLA-PUERTO RICO...TO
FAVOR RAINFALL AMOUNTS OF 05-10MM/DAY AND MAXIMA OF 15-25MM. THE
TUTT IS TO ALSO ENHANCE CONVECTION ALONG THE NET OVER NORTHERN
VENEZUELA...TO FAVOR RAINFALL AMOUNTS OF 00-05MM/DAY AND MAXIMA OF
10MM.

OTHER CONVECTION ALONG THE ITCZ IS EXPECTED ACROSS PANAMA-COSTA
RICA TO WESTERN/NORTHERN COLOMBIA. IN THIS AREA INITIALLY
EXPECTING RAINFALL AMOUNTS OF 10-15MM/DAY AND MAXIMA OF 20-30MM.
THROUGH WEDNESDAY THIS IS TO ALSO DECREASE...WITH RAINFALL AMOUNTS
OF 05-10MM/DAY AND MAXIMA OF 15-20MM. ACROSS SOUTHERN VENEZUELA TO
EASTERN COLOMBIA EXPECTING RAINFALL AMOUNTS OF 05-10MM/DAY AND
MAXIMA OF 15-20MM.

TROPICAL/EASTERLY WAVES INITIALIZED AT 12UTC:

INITIAL  24      36      48      60      72      84      96
TYPE
62W      66W     69W     DISSIPATES                           TUTT
INDUCED
74W      78W     81W     84W     87W     88W     90W     92W
TW
90W      92W     95W     97W     99W    101W    104W    106W
EW
99W     100W    102W    104W    107W    109W    111W    113W
EW

THE NHC IS MONITORING AN AREA OF DISTURBED WEATHER TO THE EAST OF
THE LESSER ANTILLES THAT EXTENDS BETWEEN 55W-47W...WITH HIGH
PROBABILITY OF IT INTENSIFYING INTO A TROPICAL CYCLONE OVER THE
NEXT DAY OR SO. THE MODELS SHOW THIS FEATURE REACHING THE ISLAND
CHAIN ON WEDNESDAY. THE BEST MOISTURE CONVERGENCE WITH THIS
FEATURE IS EXPECTED OVER THE WINDWARD ISLES...WHERE IT IS TO FAVOR
RAINFALL AMOUNTS OF 35-70MM AND MAXIMA OF 125-150MM. AS IT SLOWLY
PULLS ACROSS THE LESSER ANTILLES THIS COULD RESULT IN TOTAL
RAINFALL AMOUNTS IN EXCESS OF 250MM. ON THE LEEWARD ISLES AND OVER
NORTHERN VENEZUELA EXPECTING IT TO TRIGGER RAINFALL AMOUNTS OF
10-15MM/DAY AND MAXIMA OF 20-40MM. ON THURSDAY...AS IT MODULATES
THE ITCZ NORTH INTO THE NORTHERN WINDWARD/FRENCH ISLES THIS WILL
FAVOR RAINFALL AMOUNTS OF 10-15MM/DAY AND MAXIMA OF 20-40MM. ON
THURSDAY...FOCUS OF THE HEAVY RAINS SHIFT TO THE ABC ISLANDS WHERE
IT IS TO TRIGGER RAINFALL AMOUNTS OF 15-20MM/DAY AND MAXIMA OF
35-70MM...WHILE OVER NORTHWEST VENEZUELA EXPECT RAINFALL AMOUNTS
OF 15-20MM/DAY AND MAXIMA OF 25-50MM.

WANING TUTT OVER THE EASTERN CARIBBEAN SUSTAINS AN INDUCED TROUGH
IN THE EASTERLY TRADES WITH AXIS NORTH ALONG 62W. IN INTERACTION
WITH THE UPPER LEVEL TROUGH...THIS WILL TRIGGER SCATTERED
CONVECTION ACROSS THE VIRGIN ISLES-PUERTO RICO DURING THE DAY
TODAY...WITH RAINFALL AMOUNT OF 05-10MM/DAY AND MAXIMA OF 15-25MM
THROUGH THIS EVENING. EARLY ON WEDNESDAY MORNING IT MOVES TO THE
DOMINICAN REPUBLIC WHERE IT WILL SUSTAIN RAINFALL AMOUNTS OF
05-10MM/DAY AND MAXIMA OF 15MM. LATER ON WEDNESDAY...AS THE UPPER
TROUGH PULLS...THE INDUCED TROUGH IS TO THEN DISSIPATE.

A WEAK TROPICAL WAVE EXTENDS ALONG 74W. THIS IS TO ALSO INTERACT
WITH THE TUTT ALOFT AS IT MOVES ACROSS HAITI-WESTERN VENEZUELA TO
PANAMA. OVER NORTHERN JAMAICA AND EASTERN CUBA IT WILL FAVOR
RAINFALL AMOUNTS OF 05-10MM/DAY AND MAXIMA OF 15MM... WHILE OVER
NORTHWEST VENEZUELA TO PANAMA EXPECTING RAINFALL AMOUNTS OF
10-15MM/DAY AND MAXIMA OF 20-30MM. ON WEDNESDAY IT MOVES ACROSS
COSTA RICA/NICARAGUA TO SUSTAIN RAINFALL AMOUNTS OF 10-15MM/DAY
AND MAXIMA OF 20-35MM. ON THURSDAY IT MOVES ACROSS EL SALVADOR TO
GUATEMALA...WITH RAINFALL AMOUNTS OF 10-15MM/DAY AND MAXIMA OF
20-30MM. SIMILAR AMOUNTS ARE EXPECTED ACROSS GUATEMALA-BELIZE TO
SOUTHERN MEXICO ON FRIDAY.

AN EASTERLY WAVE ALONG 90W...IN INTERACTION WITH THE UPPER LEVEL
RIDGE OVER MEXICO-NORTHERN CENTRAL AMERICA IS FAVOR RAINFALL
AMOUNT OF 05-10MM/DAY AND MAXIMA OF 15-25MM OVER GUATEMALA AND
YUCATAN PENINSULA. ON WEDNESDAY MORNING THIS WILL THEN RESULT IN
MODERATE TO HEAVY CONVECTION ACROSS THE SOUTHERN STATES OF MEXICO
STATES...WITH ACCUMULATION OF 15-20MM/DAY AND MAXIMA OF 25-50MM.
ACROSS SOUTHWESTERN-CENTRAL MEXICO...ON THURSDAY TO
FRIDAY...EXPECTING RAINFALL AMOUNTS OF 10-15MM/DAY AND MAXIMA OF
20-35MM.

AN EASTERLY WAVE ALONG 99W IS TO ALSO INTERACT WITH THE UPPER
LEVEL RIDGE OVER MEXICO...TO TRIGGER LIGHT TO MODERATE CONVECTION
ACROSS NAYARIT/COLIMA...WITH ACCUMULATION OF 05-10MM/DAY AND
MAXIMA OF 15-20MM EXPECTED THROUGH WEDNESDAY MORNING. ON WEDNESDAY
THIS WILL INCREASE TO 15-20MM/DAY AND MAXIMA OF 25-50MM WHILE
SPREADING WEST ACROSS SOUTHWEST MEXICO. LATER ON THURSDAY AND
FRIDAY MORNING MOST ACTIVE CONVECTION WITH THIS FEATURE IS
EXPECTED OFFSHORE OVER THE EASTERN PACIFIC AND ALONG THE ITCZ TO
THE SOUTH.

AGRAMONTE...ONAMET (DOMINICAN REPUBLIC)
CASTILLO...UCR (COSTA RICA)
CONTRERAS...IMN (COSTA RICA)
DAVISON/GALVEZ...WPC (USA)
$$




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