Prognostic Meteorological Discussion
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FXCA20 KWBC 261825
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TROPICAL DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
224 PM EDT TUE SEP 26 2017

TROPICAL DISCUSSION FROM SEP 26/12 UTC: WEST OVER THE DOMAIN...A
MID/UPPER LEVEL TROUGH EXTENDS OVER THE WESTERN USA TO THE
NORTHWEST STATES OF MEXICO. DOWNSTREAM FROM THIS TROUGH A RIDGE
EXTENDS NORTH FROM THE WESTERN GULF OF MEXICO INTO THE CENTRAL
USA...WITH AXIS ANCHORING AT 250 HPA ON A CLOSED HIGH OFF THE
SOUTH COAST OF TEXAS. THIS PATTERN IS FORECAST TO HOLD DURING THE
NEXT 72-96 HRS. AS IT HOLDS...IT IS TO FAVOR A MOIST INFLOW ACROSS
THE WESTERN AND THE CENTRAL STATES OF MEXICO. OVER NORTHWEST
MEXICO THIS WILL FAVOR RAINFALL AMOUNTS OF 05-10MM/DAY AND MAXIMA
OF 15-20MM. ON WEDNESDAY-THURSDAY FOCUS OF THE CONVECTION SHIFTS
TO CHIHUAHUA-COAHUILA WITH RAINFALL AMOUNTS OF 10-15MM/DAY AND
MAXIMA OF 20-30MM. ON THURSDAY IT DECREASES TO 05-10MM/DAY AND
MAXIMA OF 15-20MM. OVER CENTRAL/SOUTHWEST MEXICO INITIALLY
EXPECTING RAINFALL AMOUNTS OF 10-15MM/DAY AND MAXIMA OF 20-35MM.
ON WEDNESDAY-THURSDAY THIS DECREASES TO 05-10MM/DAY AND MAXIMA OF
15-20MM. HIGHER AMOUNTS ARE EXPECTED TO THE NORTH ALONG THE RIO
BRAVO BASIN BETWEEN COAHUILA AND NORTHERN TAMAULIPAS...WITH
ACCUMULATION OF 20-40MM/DAY AND MAXIMA OF 50-100MM. ON
WEDNESDAY-THURSDAY THIS WILL DECREASE TO 15-20MM/DAY AND MAXIMA OF
25-50MM.

THE PATTERN ALOFT ALSO FAVORS THE NORTHWARD MODULATION OF THE
EASTERN PACIFIC ITCZ ALONG THE SOUTH COAST OF MEXICO-SOUTHERN
GUATEMALA/EL SALVADOR-NICARAGUA...WITH THE RIDGE ALOFT VENTING
DEEP CONVECTION. OVER SOUTHERN MEXICO THIS WILL SUSTAIN RAINFALL
AMOUNTS OF 20-40MM/DAY AND MAXIMA OF 50-100MM THROUGH WEDNESDAY
MORNING...AND 15-20MM/DAY AND MAXIMA OF 35-70MM ON WEDNESDAY TO
THURSDAY. ON THURSDAY TO FRIDAY THE MAXIMA PEAKS AT 20-30MM. OVER
SOUTHERN GUATEMALA-EL SALVADOR/SOUTHERN HONDURAS THIS IS TO FAVOR
RAINFALL AMOUNTS OF 10-15MM/DAY AND MAXIMA OF 20-35MM. ON
WEDNESDAY-THURSDAY THIS DECREASES TO 05-10MM/DAY AND MAXIMA OF
15-20MM...WHILE ON THURSDAY THE MAXIMA PEAKS AT 20-30MM. OVER
NORTHERN/NORTHEASTERN HONDURAS AND EASTERN NICARAGUA EXPECT
RAINFALL AMOUNTS OF 05-10MM/DAY AND MAXIMA OF 15-20MM DURING THE
NEXT FEW DAYS. OVER COSTA RICA EXPECT RAINFALL AMOUNTS OF
10-15MM/DAY AND MAXIMA OF 20-35MM. PANAMA EXPECT RAINFALL AMOUNTS
OF 05-10MM/DAY AND WIDELY ISOLATED MAXIMA OF 15-20MM. ON THURSDAY
IT INCREASES TO 10-15MM/DAY AND MAXIMA OF 20-30MM.

ANOTHER MID/UPPER LEVEL TROUGH BOUNDS THE EASTERN FRINGES OF THE
SUBTROPICAL RIDGE...WITH AXIS EXTENDING TO THE SOUTH-SOUTHWEST
ACROSS FLORIDA/EASTERN GULF OF MEXICO TO THE YUCATAN PENINSULA. AS
THE RIDGE TO THE WEST HOLDS...THE TROUGH IS TO ALSO HOLD NEARLY
UNCHANGED DURING THE NEXT THREE TO FOUR DAYS. MEANWHILE...THIS IS
TO ENHANCE CONVECTION ACROSS THE YUCATAN PENINSULA-SOUTHERN
MEXICO. OVER NORTHERN CHIAPAS-TABASCO/CAMPECHE EXPECTING RAINFALL
AMOUNTS OF 10-15MM/DAY AND MAXIMA OF 20-40MM. THROUGH THURSDAY
THIS DECREASES TO MAXIMA OF 20-30MM. OVER BELIZE AND YUCATAN
EXPECTING ACCUMULATION OF 05-10MM/DAY AND MAXIMA OF 15-20MM
THROUGH WEDNESDAY MORNING...AND 10-15MM/DAY AND MAXIMA OF 20-40MM
ON WEDNESDAY-THURSDAY. OVER THE NORTHERN YUCATAN MOST ACTIVE IS TO
CLUSTER OVER NORTHWEST PORTIONS OF THE PENINSULA...TO FAVOR
RAINFALL AMOUNTS OF 15-30MM/DAY AND MAXIMA OF 40-80MM. OVER
WESTERN-CENTRAL CUBA THIS IS TO ENHANCE DIURNAL/AIR MASS RELATED
CONVERGENCE TO TRIGGER RAINFALL AMOUNTS OF 15-30MM/DAY AND MAXIMA
OF 40-80MM. ON WEDNESDAY THIS DECREASES TO 15-20MM/DAY AND MAXIMA
OF 25-50MM. THE TROUGH IS TO ALSO VENT DEEP CONVECTION ACROSS THE
BAHAMAS. EARLY IN THE CYCLE...IN INTERACTION WITH TS MARIA TO THE
NORTH...THIS WILL RESULT IN RAINFALL AMOUNTS OF 15-30MM/DAY AND
MAXIMA OF 40-80MM. THROUGH THURSDAY MORNING...AS THE STORM
MEANDERS AWAY...THIS DECREASES TO 10-15MM/DAY AND MAXIMA OF
20-40MM. LATER IN THE DAY EXPECTING SCATTERED CONVECTION WITH
ACCUMULATION OF 05-10MM/DAY AND MAXIMA OF 15-25MM.

A CELL OF THE SUBEQUATORIAL RIDGE EXTENDS OVER THE CENTRAL/WESTERN
CARIBBEAN... WHILE ANCHORING AT 250 HPA ON A CLOSED HIGH NEAR THE
CAYMAN ISLES. THE RIDGE PATTERN ALOFT IS TO REMAIN NEARLY
STATIONARY DURING THE NEXT FEW DAYS. MEANWHILE...THIS IS TO VENT
CONVECTION ACROSS JAMAICA AND THE CAYMAN ISLES...TO INITIALLY
FAVOR RAINFALL AMOUNTS OF 15-20MM/DAY AND MAXIMA OF 25-50MM AS
ENHANCED BY THE TROUGH TO THE NORTH. ON WEDNESDAY THIS DECREASES
TO 10-15MM/DAY AND MAXIMA OF 20-40MM. ON THURSDAY...OVER THE
CAYMAN ISLES...EXPECTING RAINFALL AMOUNTS OF 15-20MM/DAY AND
MAXIMA OF 25-50MM...WHILE OVER JAMAICA EXPECTING ACCUMULATION OF
05-10MM/DAY AND MAXIMA OF 15MM.

A TUTT TO THE EAST EXTENDS FROM A CLOSED LOW NORTH OF ANTIGUA TO
THE EASTERN CARIBBEAN/NORTHERN VENEZUELA. THE TROUGH ALOFT
SUSTAINS A CONVERGENT PATTERN THAT IS INHIBITING ORGANIZED
CONVECTION ACROSS PUERTO RICO...THE VIRGIN ISLES AND THE LEEWARD
ISLANDS. THIS PATTERN PERSISTS NEARLY UNCHANGED THROUGH
THURSDAY/EARLY FRIDAY MORNING. OVER HISPANIOLA INITIALLY EXPECTING
RAINFALL AMOUNTS OF 05-10MM/DAY AND MAXIMA OF 15-20MM. ON
WEDNESDAY-THURSDAY MID/UPPER CONVERGENCE WILL THEN FAVOR A DRYING
TREND ACROSS EASTERN-CENTRAL PORTIONS OF THE ISLANDS...WITH
CONVECTION OVER HAITI/WESTERN DOMINICAN REPUBLIC TO FAVOR RAINFALL
AMOUNTS OF 05-10MM/DAY AND WIDELY ISOLATED MAXIMA OF 15MM. OVER
THE SOUTHERN WINDWARD ISLANDS/NORTHEAST VENEZUELA...THE UPPER
TROUGH WILL ENHANCE DIURNAL CONVECTION ALONG THE NEAR EQUATORIAL
TROUGH/ITCZ TO FAVOR RAINFALL AMOUNTS OF 10-15MM/DAY AND MAXIMA OF
20-30MM. ON THURSDAY THIS INCREASES TO 10-15MM/DAY AND MAXIMA OF
20-40MM. OVER CENTRAL-WESTERN VENEZUELA TO AMAZONIA IN EASTERN
COLOMBIA EXPECTING RAINFALL AMOUNTS OF 10-15MM/DAY AND MAXIMA OF
20-30MM...WHILE ACROSS NORTHERN COLOMBIA EXPECTING ACCUMULATION OF
10-15MM/DAY AND MAXIMA OF 20-40MM. ON THURSDAY THE DAILY MAXIMA
DECREASES TO 20-30MM.

TROPICAL/EASTERLY WAVES INITIALIZED AT 12UTC:
INITIAL   24    36    48    60    72    84    96   TYPE  SOF
34W      37W   40W   43W   46W   49W   51W   53W   TW    24N
42W      44W   47W   49W   52W   DISSIPATES  TUTT-INDCD  20N
72W      74W   77W   79W   81W   83W   85W   87W   TW    18N

A TROPICAL WAVE ALONG 34W AND SOUTH OF 24N IS TO CONFINE TO THE
ITCZ DURING THE NEXT FEW DAYS.

THE TUTT OVER THE CENTRAL ATLANTIC SUSTAINS AN INDUCED TROUGH IN
THE EASTERLY TRADES WITH AXIS ALONG 42W. ON THURSDAY THIS IS
FORECAST TO DISSIPATE WHILE MEANDERING WEST ALONG THE ATLANTIC
ITCZ.

TROPICAL WAVE ALONG 72W AND SOUTH OF 18N IS TO SUSTAIN ORGANIZED
CONVECTION ACROSS NORTHWEST VENEZUELA/NORTHERN COLOMBIA...TO
TRIGGER RAINFALL AMOUNTS OF 10-15MM/DAY AND MAXIMA OF 20-40MM
DURING THE NEXT COUPLE OF DAYS. ACROSS THE DOMINICAN REPUBLIC THIS
WILL FAVOR RAINFALL AMOUNTS OF 05-10MM/DAY AND MAXIMA OF 15-20MM.
ON WEDNESDAY IT IS TO THEN TRIGGER SCATTERED CONVECTION ACROSS
JAMAICA TO FAVOR RAINFALL AMOUNTS OF 10-15MM/DAY AND MAXIMA OF
20-40MM. OVER PANAMA IT WILL THEN TRIGGER RAINFALL AMOUNTS OF
05-10MM/DAY AND MAXIMA OF 15-20MM ON WEDNESDAY-THURSDAY. ON
THURSDAY-FRIDAY FOCUS OF THE CONVECTION SHIFTS TO COSTA
RICA/SOUTHERN NICARAGUA...WHERE IT WILL SUSTAIN RAINFALL AMOUNTS
OF 10-15MM/DAY AND MAXIMA OF 20-30MM. OVER NORTHEAST
NICARAGUA/NORTHEAST HONDURAS IT WILL RESULT IN ACCUMULATION OF
05-10MM/DAY AND MAXIMA OF 15-20MM.

GUY...NMS (BELIZE)
RIVAS...SENAMHI (PERU)
DAVISON/GALVEZ...WPC (USA)

$$





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