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Tropical Discussion
 
(Caution: Version displayed is not the latest version. - Issued 1918Z Sep 24, 2018)
 
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TROPICAL DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
318 PM EDT MON SEP 24 2018

TROPICAL DISCUSSION FROM SEP 24/12 UTC: WEST IN THE DOMAIN AND AT
UPPER LEVELS...THE SUBTROPICAL RIDGE IS FORECAST TO MEANDER ACROSS
WESTERN MEXICO THROUGH THE CYCLE. TO THE EAST OF THE HIGH...A TUTT
LOW CENTERS TO THE NORTHWEST OF THE YUCATAN PENINSULA...AND IS
FORECAST TO MEANDER TOWARDS SOUTHERN VERACRUZ BY WEDNESDAY EVENING
WHILE WEAKENING. THE TUTT WILL INITIALLY INTERACT WITH A MOIST
PLUME CROSSING THE YUCATAN PENINSULA. GIVEN THAT THE LOW-LEVEL
WINDS ARE 15-20KT AT 850 HPA...ENHANCED LOW-LEVEL SHEAR WILL LIMIT
POTENTIAL ACCUMULATIONS TO SUSTAIN 10-15MM/DAY AND MAXIMA OF
20-30MM IN MOST OF THE PENINSULA...AND 15-20MM/DAY AND MAXIMA OF
25-50MM IN CAMPECHE AND AREAS TO THE SOUTH. AFTER THIS
PERIOD...ALTHOUGH THE TROUGH WILL LINGER IN THE
REGION...ACCUMULATIONS IN THE YUCATAN PENINSULA ARE FORECAST TO
GRADUALLY DECREASE AS TROPOSPHERIC MOISTURE AVAILABILITY
DECREASES. THIS WILL SUSTAIN MAXIMA OF 20-40MM/DAY IN WESTERN AND
SOUTHERN YUCATAN PENINSULA AND MAXIMA OF 15MM TO THE NORTH.
SIMILAR ACCUMULATIONS ARE EXPECTED ON WEDNESDAY...WHILE A FURTHER
DECREASE IS EXPECTED TO THE SOUTH.

TO THE WEST AND TO THE SOUTH OF MEXICO...A ROBUST EASTERLY WAVE IS
PROPAGATING NEAR 106W (SEE BELOW)...AND WILL AID WITH THE
TRANSPORT OF MOISTURE INTO SOUTHERN PARTS OF THE GULF OF
CALIFORNIA THROUGH THE CYCLE. THIS WILL SUSTAIN A SEASONALLY
ACTIVE PATTERN OF CONVECTION WITH ACCUMULATIONS IN THE ORDER OF
10-15MM/DAY AND MAXIMA OF 20-40MM/DAY THROUGH THE CYCLE. LARGER
AMOUNTS ARE EXPECTED IN SOUTHERN MEXICO AS MOIST PLUME INTERACTS
WITH THE SIERRA MADRE DEL SUR. THROUGH EARLY TUESDAY...THIS WILL
SUSTAIN 15-20MM/DAY AND MAXIMA OF 25-50MM FROM GUATEMALA WEST INTO
OAXACA/VERACRUZ. BY TUESDAY-WEDNESDAY...EXPECTING SIMILAR
ACCUMULATIONS CLUSTERING FROM OAXACA WEST INTO COLIMA.
ACCUMULATIONS WILL DECREASE AFTER.

ALSO IN MEXICO...A SURFACE FRONT IS FORECAST TO ARRIVE INTO
NORTHERN COAHUILA AND EASTERN CHIHUAHUA ON WEDNESDAY. THIS WILL
LEAD TO SOME ENHANCEMENT OF CONVECTION TO SUSTAIN 05-10MM/DAY AND
MAXIMA OF 15-20MM IN CHIHUAHUA ON WEDNESDAY-THURSDAY...AND
05-10MM/DAY AND MAXIMA OF 15-25MM IN EASTERN COAHUILA AND NORTHERN
NUEVO LEON IN ASSOCIATION WITH THE PRE-FRONTAL TROUGH.

NORTH ACROSS THE NORTH ATLANTIC...WHILE A LOW-LEVEL PERTURBATION
CENTERS NEAR 30N 74W...AN INDUCED TROUGH WILL ENHANCE ACTIVITY
OVER THE BAHAMAS AND WESTERN CUBA EARLY IN THE CYCLE. MOISTURE IN
THE COLUMN IS LIMITED...THUS ACCUMULATIONS WILL LIMIT TO THE
05-10MM/DAY RANGE AND ISOLATED MAXIMA OF 15-20MM THROUGH THE CYCLE
ACROSS THE NORTHWEST BAHAMAS AND WESTERN CUBA. SOME ENHANCEMENT IS
EXPECTED ON WESTERN CUBA ON TUESDAY...WHERE MAXIMA WILL REACH
20-30MM.

A TUTT IS DIGGING OVER THE NORTHEASTERN CARIBBEAN AND IS
INTERACTING WITH THE REMNANTS OF TROPICAL DEPRESSION ELEVEN...NOT
INITIALIZED AS AN INDUCED TROUGH/EASTERLY WAVE. THIS WILL LEAD TO
MODERATE PRECIPITATION AS IT MOVES ACROSS THE LEEWARD ISLANDS ON
MONDAY...PUERTO RICO ON TUESDAY AND HISPANIOLA ON WEDNESDAY. THE
TUTT IS ALSO FORECAST TO RETROGRESS THROUGH THE CYCLE TO CENTER ON
A LOW JUST TO THE SOUTHEAST OF PUERTO RICO ON MONDAY...OVER THE
MONA PASSAGE ON TUESDAY...AND OVER THE WINDWARD PASSAGE/JAMAICA ON
WEDNESDAY. IN TERMS OF RAINFALL ACCUMULATIONS...THROUGH EARLY
TUESDAY EXPECTING MAXIMA OF 20-40MM/DAY IN THE LEEWARD ISLANDS AND
MAXIMA OF 20-30MM/DAY IN PUERTO RICO. BY TUESDAY-WEDNESDAY...AS
THE MOIST PLUME INTERACTS WITH THE OROGRAPHY OF PUERTO RICO AND
EASTERN HISPANIOLA EXPECTING 15-20MM/DAY AND MAXIMA OF 35-70MM.
TRAILING MOIST PLUME IN THE LEEWARD ISLANDS WILL SUSTAIN MAXIMA OF
20-30MM. BY WEDNESDAY-EARLY THURSDAY EXPECTING 15-20MM/DAY AND
MAXIMA OF 30-60MM MOSTLY IN HISPANIOLA...WHILE MAXIMA DECREASES TO
15-25MM TO THE EAST.

ALSO RELEVANT TO THE FORECAST...A TROPOSPHERIC KELVIN WAVE IS
FORECAST TO CROSS SOUTHERN CENTRAL AMERICA ON WEDNESDAY-THURSDAY.
MODELS ALL AGREE ON AN ENHANCEMENT OF CONVECTION ACROSS THE
REGION...MOSTLY TO AFFECT AREAS FROM COSTA RICA/NICARAGUA EAST
ACROSS PANAMA INTO COLOMBIA. NOTICE THAT IN THIS REGIONS...A MOIST
POOL AND SLOW-MOVING MID-LEVEL TROUGH IS SUSTAINING A SEASONALLY
ACTIVE PATTERN OF CONVECTION ON A DAILY BASIS. THROUGH EARLY
TUESDAY...EXPECTING 15-20MM/DAY AND MAXIMA OF 30-60MM IN WESTERN
PANAMA...COSTA RICA INTO SOUTHERN NICARAGUA. TO THE EAST ACROSS
CENTRAL PANAMA INTO NORTHWEST COLOMBIA EXPECTING MAXIMA OF
25-50MM. BY TUESDAY-WEDNESDAY... EXPECTING MAXIMA INCREASING TO
35-70MM IN NORTHWEST COLOMBIA...WHILE EXPECTING MAXIMA OF 25-50MM
IN NICARAGUA AND COSTA RICA. IN PANAMA EXPECTING MAXIMA OF
20-40MM. BY WEDNESDAY-THURSDAY...EXPECTING LARGEST ACCUMULATIONS
IN WESTERN PANAMA AND COSTA RICA WHERE EXPECTING MAXIMA OF
30-60MM...WHILE IN NORTHWEST COLOMBIA EXPECTING MAXIMA OF 25-50MM.

TO THE SOUTH OF 15N...ACTIVITY WILL BE MOSTLY SENSITIVE TO WAVES
IN THE TRADES (SEE BELOW).

TROPICAL/EASTERLY WAVES/TRADE WIND SURGES FROM 00 UTC:
INITIAL 24    36    48    60    72    84    96    TYPE     SOF
39W    42W   46W   50W   54W   57W   59W   61W    TW       14N
52W    55W   58W   62W   65W   68W   72W   77W    TW       16N
59W    61W   64W   67W   70W   73W   76W   80W  I/EW       18N
95W    97W   99W  101W  102W   DISSIPATES         TW       15N
105W  106W  107W  109W  110W  112W  114W  115W    EW       17N

A TROPICAL WAVE IS INITIALIZED AT 39W AND IS ASSOCIATED WITH THE
REMNANTS OF TROPICAL DEPRESSION KIRK. THIS WAVE WILL ENHANCE
ACTIVITY ONCE IT ARRIVES IN THE WINDWARD ISLANDS AND CENTRAL
LESSER ANTILLES ON THURSDAY.

A TROPICAL WAVE IS PROPAGATING AT 52W AND WILL ENHANCE ACTIVITY TO
THE SOUTH OF 15N. IT WILL LEAD TO MAXIMA OF 20-40MM/DAY IN
TRINIDAD AND TOBAGO AND NORTHEAST VENEZUELA ON
TUESDAY-WEDNESDAY...AND FAVOR MAXIMA OF 20-30MM IN CENTRAL/WESTERN
VENEZUELA ON WEDNESDAY-THURSDAY.

A TROUGH IN THE TRADES...ORIGINALLY TROPICAL DEPRESSION
ELEVEN...IS NOW INTERACTING WITH A TUTT WHILE PROPAGATING ALONG
59W. THIS WILL MOVE IN SYNCHRONY WITH THE TUTT TO ENHANCE ACTIVITY
ACROSS THE LEEWARD ISLANDS ON MONDAY...PUERTO RICO ON
TUESDAY...AND HISPANIOLA ON WEDNESDAY.
A TROPICAL WAVE INITIALIZED AT 95W IS FORECAST TO RAPIDLY LOSE
DEFINITION AS IT INTERACTS WITH ITCZ LOWS.

AN EASTERLY WAVE EXTENDS ALONG 105W...AND ITS MAIN ROLE ON THE
FORECAST WILL BE TO MAINTAIN DEEP-LAYER MOISTURE IN SOUTHWESTERN
AND WESTERN MEXICO...TO SUSTAIN MAXIMA OF 20-40MM IN AREAS BETWEEN
JALISCO AND SINALOA.

WARD-FORBES...BDM (THE BAHAMAS)
TEJADA...AAC (PANAMA)
DAVISON/GALVEZ...WPC (USA)