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Tropical Discussion
 
(Caution: Version displayed is not the latest version. - Issued 1831Z Jul 18, 2018)
 
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TROPICAL DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
231 PM EDT WED JUL 18 2018

TROPICAL DISCUSSION FROM JUL 18/12 UTC: AT 250 HPA...A HIGH OVER
NEW MEXICO IN THE SOUTHWEST USA EXTENDS A RIDGE EAST ACROSS THE
SOUTHERN USA/GULF OF MEXICO TO THE BAHAMAS/WESTERN ATLANTIC. RIDGE
PATTERN ALOFT IS FORECAST TO HOLD...BUILDING SOUTH ACROSS MEXICO
WHILE GENERALLY HOLDING OVER THE GULF OF MEXICO-THE
BAHAMAS/SOUTHWEST ATLANTIC. AS IT BUILDS ACROSS MEXICO THIS WILL
STEER A TUTT LOW ALONG THE SOUTHWEST COAST...WHICH IS FORECAST TO
MOVE ALONG THE COAST OF OAXACA-GUERRERO EARLY IN THE CYCLE...TO
COLIMA-NAYARIT LATER ON FRIDAY. EARLY IN THE CYCLE WILL ENHANCE
DIURNAL CONVECTION BETWEEN COLIMA/NAYARIT AND OAXACA...TO FAVOR
RAINFALL AMOUNTS OF 05-10MM/DAY AND MAXIMA OF 15-20MM. ALONG THE
SIERRA MADRE...BETWEEN SONORA-SINALOA...THE RIDGE ALOFT IS TO VENT
DIURNAL CONVECTION TO FAVOR RAINFALL AMOUNTS OF 05-10MM/DAY AND
MAXIMA OF 15-20MM/DAY...INCREASING TO 10-15MM/DAY AND MAXIMA OF
20-30MM/DAY BY FRIDAY-SATURDAY.

ANOTHER TUTT TO THE SOUTH OF THE SUBTROPICAL RIDGE EXTENDS WEST
FROM A CLOSED LOW TO THE NORTHEAST OF THE LEEWARD ISLANDS...ACROSS
THE GREATER ANTILLES/NORTHWEST CARIBBEAN. DURING THE DAY ON
THURSDAY THE TROUGH IS TO MEANDER SOUTH OF THE GREATER
ANTILLES...MEANWHILE PRESSING AGAINST A BROAD CELL OF THE
SUBEQUATORIAL RIDGE TO THE SOUTH. AS IT MEANDERS OVER THE GREATER
ANTILLES...THE TROUGH ALOFT IS TO ENHANCE CONVECTIVE DEVELOPMENT
IN ASSOCIATION WITH TROPICAL WAVES STREAMING ACROSS THE BASIN (SEE
BELOW FOR DETAILS). THE TROUGH IS TO ALSO ENHANCE DIURNAL
CONVECTION...WITH ACTIVITY ACROSS CUBA TO RESULT IN RAINFALL
AMOUNTS OF 05-10MM/DAY AND MAXIMA OF 15MM. ISOLATED HIGHER AMOUNTS
ARE EXPECTED IN SOUTHEASTERN CUBA ON FRIDAY-SATURDAY. OVER JAMAICA
MOST ACTIVE IS EXPECTED ALSO ON FRIDAY-SATURDAY...WHEN
ACCUMULATION ARE FORECAST TO REACH 05-10MM/DAY AND MAXIMA OF
15-20MM. ACROSS HISPANIOLA EXPECTING RAINFALL AMOUNTS OF
05-10MM/DAY AND MAXIMA OF 15-20MM/DAY...WITH A PEAK ON THURSDAY AS
THE TROPICAL WAVE MOVES ACROSS. OVER THE ISLAND CHAIN EXPECTING
RAINFALL AMOUNTS OF 05-10MM/DAY AND MAXIMA OF 15-25MM THROUGH
EARLY THURSDAY...WITH HIGHER AMOUNTS OVER
TRINIDAD/TOBAGO-GRENADINES-NORTHEAST VENEZUELA. IN THIS AREA
EXPECTING RAINFALL AMOUNTS OF 10-15MM/DAY AND MAXIMA OF 20-35MM.
ACCUMULATIONS ARE FORECAST TO RAPIDLY DECREASE AFTER.

ALSO...AS THE TUTT MEANDERS SOUTH OVER THE NORTHERN
CARIBBEAN...SOME ENHANCEMENT IS EXPECTED OVER NORTHERN CENTRAL
AMERICA. OVER BELIZE-GUATEMALA-CHIAPAS IN SOUTHERN MEXICO AND
PORTIONS OF HONDURAS EXPECTING RAINFALL AMOUNTS OF 10-15MM/DAY AND
MAXIMA OF 20-45MM ON WEDNESDAY-THURSDAY...WHILE OVER THE WESTERN
YUCATAN PENINSULA EXPECTING ACCUMULATION OF 05-10MM/DAY AND MAXIMA
OF 15MM. LESSER AMOUNTS ARE EXPECTED ON THURSDAY AND ON AS A DRY
SAHARAN AIR LAYER ENTRAINS FROM THE EAST.

AFOREMENTIONED CELL OF THE SUBEQUATORIAL RIDGE CONFINES TO CENTRAL
AMERICA/WESTERN CARIBBEAN-COLOMBIA...WITH AXIS ANCHORING ON A 250
HPA HIGH OVER THE SOUTHERN CARIBBEAN. UNDER PRESSURE FROM THE TUTT
TO THE NORTH...THE RIDGE GRADUALLY BECOMES ILL ORGANIZED LATER IN
THE PERIOD. INITIALLY THIS IS TO VENT CONVECTION ACROSS EASTERN
NICARAGUA TO FAVOR RAINFALL AMOUNTS OF 05-10MM/DAY AND MAXIMA OF
15MM. OVER COSTA RICA TO WESTERN PANAMA...AS IT VENTS ITCZ RELATED
CONVECTION...EXPECTING RAINFALL AMOUNTS OF 10-15MM/DAY AND MAXIMA
OF 20-45MM THROUGH FRIDAY MORNING. OVER EASTERN PANAMA TO WESTERN
COLOMBIA EXPECTING RAINFALL AMOUNTS OF 10-15MM/DAY AND MAXIMA OF
20-35MM...WITH HIGHER AMOUNTS ON THURSDAY-FRIDAY AS A TROPICAL
WAVE STREAMS ACROSS THE CENTRAL CARIBBEAN. OVER VENEZUELA TO
EASTERN COLOMBIA EXPECTING RAINFALL AMOUNTS OF 15-20MM/DAY AND
MAXIMA OF 25-50MM/DAY...WHILE OVER THE GUIANAS EXPECT RAINFALL
AMOUNTS OF 05-10MM/DAY AND MAXIMA OF 15-20MM/DAY THROUGH
SATURDAY...DECREASING DRAMATICALLY AFTER.

TROPICAL/EASTERLY WAVES/TRADE WIND SURGES FROM 00 UTC:
INITIAL 24    36    48    60    72    84    96    TYPE      SOF
59W     64W   68W   73W   78W   82W   86W   90W    TW       23N
86W     90W   94W   97W  100W  104W  108W  112W    TW       20N

A PROGRESSIVE TROPICAL WAVE IS INITIALIZED ALONG 59W AND SOUTH OF
23N. THE METEOSAT DUST PRODUCT SHOWS A DRY AND DUSTY SAHARAN AIR
LAYER (SAL) TRAILING THIS WAVE... SPANNING BETWEEN 54W AND THE
COAST OF AFRICA. AS IT INTERACTS WITH THE TUTT ALOFT...MOST ACTIVE
CONVECTION WITH THIS WAVE IS BUILDING ALONG THE BASE AND THE
WESTERN HALF OF THIS WAVE. THIS WILL AFFECT THE ISLAND CHAIN EARLY
IN THE CYCLE AND THE VIRGIN ISLES EARLY ON THURSDAY
MORNING...MEANWHILE FAVORING RAINFALL AMOUNTS OF 05-10MM/DAY AND
MAXIMA OF 15-25MM. OVER TRINIDAD/TOBAGO-GRENADINES-NORTHEAST
VENEZUELA THIS WILL SUSTAIN RAINFALL AMOUNTS OF 10-15MM/DAY AND
MAXIMA OF 20-35MM. ON THURSDAY...IN INTERACTION WITH THE NET OVER
VENEZUELA/EASTERN COLOMBIA...THIS WILL THEN SUSTAIN RAINFALL
AMOUNTS OF 15-20MM/DAY AND MAXIMA OF 25-50MM. OVER PUERTO RICO AND
HISPANIOLA...MEANWHILE...EXPECTING RAINFALL AMOUNTS OF 10-15MM/DAY
AND MAXIMA OF 20-45MM...WITH LOCALLY HIGHER AMOUNTS HIGHLY
PROBABLE AS ENHANCED BY DIURNAL HEATING OVER THE LARGER ISLANDS.
ACROSS COLOMBIA IT IS TO THEN SUSTAIN RAINFALL AMOUNTS OF
15-20MM/DAY AND MAXIMA OF 25-50MM...WITH LOCALLY HIGHER OVER
WESTERN COLOMBIA/ANDEAN REGION EARLY ON FRIDAY MORNING AS IT
INTERACTS WITH THE PANAMANIAN TROUGH. OVER JAMAICA-EASTERN CUBA
THIS IS TO THEN SUSTAIN RAINFALL AMOUNTS OF 05-10MM/DAY AND MAXIMA
OF 15-20MM ON FRIDAY...WHILE OVER EASTERN PANAMA EXPECTING
RAINFALL AMOUNTS OF 15-20MM/DAY AND MAXIMA OF 25-50MM THROUGH
EARLY FRIDAY...AHEAD OF THE WAVE AXIS. OVER WESTERN PANAMA-COSTA
RICA THIS IS TO THEN TRIGGER RAINFALL AMOUNTS OF 15-20MM/DAY AND
MAXIMA OF 30-60MM ON FRIDAY-SATURDAY. THE WAVE ENTERS EASTERN
NICARAGUA/NORTHEAST HONDURAS ON SATURDAY MORNING...TO SUSTAIN
RAINFALL AMOUNTS OF 05-10MM/DAY AND MAXIMA OF 15-25MM. ACROSS EL
SALVADOR/ HONDURAS THIS IS TO THEN TRIGGER LIGHTER RAINFALL
ACCUMULATIONS.

A TROPICAL WAVE ALONG 86W AND TO THE SOUTH OF 20N IS TO TRIGGER
DEEP CONVECTION ACROSS HONDURAS-BELIZE-GUATEMALA-CHIAPAS IN
SOUTHERN MEXICO EARLY IN THE CYCLE...WITH ACCUMULATIONS OF
10-15MM/DAY AND MAXIMA OF 20-45MM. OVER THE WESTERN YUCATAN
PENINSULA THIS WILL FAVOR LESSER AMOUNTS...WITH ACCUMULATION OF
05-10MM/DAY AND MAXIMA OF 15MM.  ON THURSDAY...AS IT MOVES ACROSS
OAXACA TO GUERRERO...THIS WILL SUSTAIN RAINFALL AMOUNTS OF
10-15MM/DAY AND MAXIMA OF 20-30MM. OVER CENTRAL AND SOUTHWEST
MEXICO THIS WILL THEN TRIGGER RAINFALL AMOUNTS OF 05-10MM/DAY AND
MAXIMA OF 15-20MM.

HUDSON...MS (JAMAICA)
HERNANDEZ...IMTA (MEXICO)
WARD-FORBES...BDM (THE BAHAMAS)
DAVISON/GALVEZ...WPC (USA)