Prognostic Meteorological Discussion
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FXCA20 KWBC 231855
PMDCA

TROPICAL DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
255 PM EDT FRI JUN 23 2017

TROPICAL DISCUSSION FROM JUNE 23/12 UTC: CONVECTION AND
PRECIPITATION ARE ACTIVATING IN MEXICO DUE TO DIFFERENT FACTORS. A
MOIST PLUME IS BEING ADVECTED WESTWARD ACROSS THE GULF OF MEXICO
TO ARRIVE IN THE COAST OF MEXICO LATE ON FRIDAY. THIS MOISTURE
SURGE WILL BE LATER REINFORCED BY A TROPICAL WAVE THAT IS TO
ARRIVE IN THE REGION DURING SATURDAY-SUNDAY. THIS WILL SUSTAIN
ACTIVE CONVECTION ALONG THE GULF COAST AND ALONG THE SIERRA MADRE
ORIENTAL...AND THE EJE VOLCANICO. ALSO IN MEXICO...A BROAD LOW TO
THE SOUTH OF OAXACA/GUERRERO IS STIMULATING THE TRANSPORT OF ITCZ
MOISTURE INTO THE GULF OF TEHUANTEPEC REGION. THIS WILL CONTINUE
ENHANCING LOW-LEVEL MOISTURE CONVERGENCE AND OROGRAPHIC ASCENT
ALONG THE SOUTHERN COAST OF MEXICO...WHILE REGIONS OF HEAVY
PRECIPITATION SPREAD WESTWARD THROUGH THE CYCLE. AT UPPER
LEVELS...TUTT LOW IS FORECAST TO MEANDER FROM THE WESTERN YUCATAN
PENINSULA ON FRIDAY TO THE NORTHWESTERN GULF OF MEXICO BY
SATURDAY-SUNDAY...WHERE IT WILL LOSE DEFINITION. WHILE THE TUTT
MEANDERS NORTH...AN UPPER RIDGE AXIS IS FORECAST TO DEVELOP ALONG
MOST OF BELIZE-GUATEMALA WEST INTO GUERRERO...IN RESPONSE TO
ACTIVE CONVECTION IN THE PACIFIC BASIN. THROUGH EARLY
SATURDAY...LARGEST ACCUMULATIONS WILL EXTEND FROM GUATEMALA/BELIZE
WEST INTO EASTERN GUERRERO/OAXACA/CENTRAL VERACRUZ...WHERE
AFTERNOON THUNDERSTORMS WILL PRODUCE 15-20MM/DAY AND MAXIMA OF
30-60MM. AS MOISTURE AND VENTILATION IN ASSOCIATION WITH THE
TUTT-LOW INCREASE...EXPECTING AN INCREASE IN DIURNAL CONVECTION
ACROSS HIDALGO/NORTHERN VERACRUZ INTO THE EJE VOLCANICO AND
MICHOACAN/COLIMA...WHERE EXPECTING 05-10MM/DAY AND MAXIMA OF
15-25MM. BY SATURDAY-SUNDAY EXPECTING AMOUNTS OF 15-20MM/DAY AND
MAXIMA OF 35-70MM FROM GUATEMALA WEST INTO CENTRAL VERACRUZ AND
SOUTHERN MICHOACAN. ACROSS HIDALGO/NORTHERN VERACRUZ/SAN LUIS
POTOSI...ACROSS THE EJE VOLCANICO AND INTO JALISCO EXPECTING
10-15MM/DAY AND MAXIMA OF 20-45MM. BY SUNDAY-MONDAY...EXPECTING A
SIGNIFICANT INCREASE ACROSS SOUTHERN GUERRERO INTO SOUTHERN
MICHOACAN. IN THESE REGIONS...ENHANCED MOISTURE TRANSPORT FROM THE
SOUTHEAST WILL SUSTAIN AMOUNTS OF 25-50MM/DAY AND MAXIMA OF
75-100MM. ACROSS CHIAPAS/TABASCO AND VERACRUZ EXPECTING
15-20MM/DAY AND MAXIMA OF 25-50MM. ACROSS THE EJE VOLCANICO AND
INTO TAMAULIPAS/SIERRA MADRE ORIENTAL...EXPECTING 10-15MM/DAY AND
MAXIMA OF 20-45MM. INCREASING INSTABILITY ALONG THE SIERRA MADRE
OCCIDENTAL WILL SUSTAIN 05-10MM/DAY AND MAXIMA OF 15MM IN EVENING
THUNDERSTORMS.

IN NORTHERN CENTRAL AMERICA...ACTIVE CONVECTION WILL BE PRESENT AS
AFOREMENTIONED TUTT PROVIDES VENTILATION AND CONTINUES SUSTAINING
A NORTHWARD UNDULATION OF THE ITCZ. FURTHERMORE...A TROPICAL WAVE
IS FORECAST TO CROSS THE REGION...WHICH WILL ENHANCE MOISTURE
CONTENT AS WELL. THIS WILL SUSTAIN MAXIMA OF 30-60MM/DAY FROM
NORTHWESTERN NICARAGUA TO CHIAPAS/BELIZE ON FRIDAY-SATURDAY...AND
MAXIMA OF 35-70MM/DAY FROM SOUTHERN BELIZE AND MOST OF GUATEMALA
INTO CHIAPAS ON SATURDAY-SUNDAY. BY SUNDAY-MONDAY...A POCKET OF
TRADE WIND SHOWERS WILL ARRIVE INTO WESTERN HONDURAS/EL
SALVADOR/GUATEMALA FROM THE CARIBBEAN. THIS WILL INTERACT WITH THE
DIURNAL CYCLE OF SOLAR RADIATION AND WITH A WEAK TUTT ALOFT TO
SUSTAIN 10-15MM/DAY AND MAXIMA OF 20-40MM. LIGHTER AMOUNTS ARE
EXPECTED ACROSS THE YUCATAN PENINSULA...WHERE DIURNAL CONVECTION
WILL LEAD TO 05-10MM/DAY AND ISOLATED MAXIMA OF 15-25MM ON
FRIDAY...GRADUALLY DECREASING TO MAXIMA OF 15MM BY SUNDAY.

IN THE NORTHWESTERN ANTILLES...ACTIVITY WILL BE INITIALLY
STIMULATED BY THE TUTT AND MOISTURE TRAILING BEHIND THE
AFOREMENTIONED TROPICAL WAVE. THIS WILL SUSTAIN MAXIMA OF
15-25MM/DAY IN EXTREME NORTHWESTERN CUBA. AMOUNTS SHOULD GRADUALLY
DECREASE IN RELATION TO THESE SYSTEMS. YET...DIURNAL INSTABILITY
IN JAMAICA WILL SUSTAIN THE CHANCE FOR AFTERNOON THUNDERSTORMS ON
A DAILY BASIS WITH ACCUMULATIONS OF 05-10MM/DAY AND VERY ISOLATED
MAXIMA OF 15-20MM THROUGH SUNDAY...DECREASING AFTER. CENTRAL
CUBA...THUNDERSTORMS WILL INCREASE IN COVERAGE ON
SUNDAY-MONDAY...BUT MAXIMA WILL LIMIT UNDER 15MM.

IN THE REST OF THE CARIBBEAN...EXPECTING A GRADUAL INCREASE
THROUGH SUNDAY AS A TROPICAL WAVE APPROACHES FROM THE EAST (SEE
BELOW). A SAHARAN AIR LAYER AND TRADE WIND SURGE TRAIL
BEHIND...WHICH WILL LEAD TO A DECREASE IN ACTIVITY DURING THE
BEGINNING OF THE WORK WEEK. INITIALLY...ACTIVITY WILL BE MODULATED
BY A REGION OF TRADE WIND CONVERGENCE AND ENHANCED SHOWERS...WHICH
WILL LEAD TO 05-10MM/DAY AND ISOLATED MAXIMA OF 15MM FROM SAINT
LUCIA NORTH INTO THE LESSER ANTILLES/VIRGIN ISLANDS AND PUERTO
RICO THROUGH EARLY SATURDAY. AMOUNTS WILL THEN INCREASE TO
05-10MM/DAY AND MAXIMA OF 15-20MM/DAY BY SATURDAY-SUNDAY FROM
GUADELOUPE SOUTH INTO NORTHEASTERN VENEZUELA/TRINIDAD AND TOBAGO.
BY SUNDAY-MONDAY...ACTIVITY WILL PEAK AS TROPICAL WAVE CROSSES THE
REGION. THIS WILL SUSTAIN 10-15MM/DAY AND MAXIMA OF 20-30MM FROM
GUADELOUPE TO NORTHEASTERN VENEZUELA...AND ACROSS ALL OF THE
WINDWARD ISLANDS. AMOUNTS ARE DECREASING AFTER.

IN PANAMA AND COSTA RICA...ACTIVITY WILL BE LARGELY SENSITIVE TO
THE INFLUENCE OF THE ITCZ/NET. MODELS AGREE ON A BROAD AREA OF
ACTIVE CONVECTION DEVELOPING DURING EARLY NEXT WEEK...IN
ASSOCIATION WITH A STRENGTHENING AND BROADENING OF THE PANAMANIAN
LOW...AND ENHANCED UPPER VENTILATION AIDED BY THE WESTERN
PERIPHERY OF AN UPPER RIDGE THAT IS TO EXTEND ALONG THE NORTHERN
COAST OF VENEZUELA AND COLOMBIA BY SUNDAY-MONDAY. IN THE MEAN
TIME...LARGEST ACCUMULATIONS THROUGH EARLY TUESDAY WILL FOCUS IN
PANAMA WHERE EXPECTING 10-15MM/DAY ND ISOLATED MAXIMA OF 20-35MM
ON FRIDAY. IN COSTA RICA...EXPECTING GENERALLY FAIR CONDITIONS
THROUGH EARLY SUNDAY AS A STABLE AND DRY AIR MASS ARRIVES FROM THE
CARIBBEAN. THIS WILL LIMIT MAXIMA TO 15MM THROUGH THIS PERIOD. A
NEW BURST IN CONVECTION IS EXPECTED START AFFECTING SOUTHERN COSTA
RICA/PANAMA ON SUNDAY-MONDAY...WHEN EXPECTING 10-15MM/DAY AND
MAXIMA OF 20-40MM.

ACTIVITY IN NORTHERN SOUTH AMERICA WILL CONTINUE CLUSTERING ALONG
THE ITCZ/NET. THE NET IS FORECAST TO MEANDER BACK NORTH THROUGH
THE CYCLE...WHICH WILL LEAD TO A RELOCATION OF LARGEST
ACCUMULATIONS FROM SOUTHERN VENEZUELA AND THE GUIANAS ON
FRIDAY...TO CENTRAL VENEZUELA BY SATURDAY AND ON. THE UPPER FLOW
PATTERN WILL REMAIN FAVORABLE FOR ENHANCED UPPER DIVERGENCE AND
HEAVY RAINFALL THROUGH THE CYCLE...ALTHOUGH THE MOST SIGNIFICANT
ENHANCEMENT WILL MEANDER WESTWARD FROM THE GUIANAS/EASTERN
VENEZUELA ON FRIDAY TO COLOMBIA ON SUNDAY-TUESDAY. WAVES IN THE
TRADES WILL ALSO PLAY A ROLE IN ENHANCING ACTIVITY...ESPECIALLY
ACROSS THE GUIANAS ON SATURDAY THROUGH MONDAY. THROUGH EARLY
SATURDAY...LARGEST ACCUMULATIONS ARE EXPECTED ACROSS THE GUIANAS
WEST INTO NORTHEASTERN COLOMBIA...CENTRAL AND SOUTHERN VENEZUELA
WHERE EXPECTING 15-20MM/DAY AND MAXIMA OF 25-50MM. A TROUGH IN THE
TRADES/EASTERLY WAVE CROSSING NORTHEASTERN VENEZUELA ON FRIDAY
WILL ALSO STIMULATE CONVECTION LOCALLY TO PRODUCE MAXIMA OF
15-20MM/DAY FROM DELTA AMACURO WEST INTO GUARICO/MIRANDA. BY
SATURDAY-SUNDAY...EXPECTING MAXIMA OF 25-50MM/DAY ACROSS THE
NORTHERN GUIANAS INTO SOUTHEASTERN VENEZUELA...AND MAXIMA OF
20-45MM/DAY ACROSS MOST OF CENTRAL VENEZUELA. BY SUNDAY-MONDAY
EXPECTING MAXIMA OF 25-50MM/DAY FROM GUYANA WEST INTO WESTERN
VENEZUELA...AIDED BY THE TROPICAL WAVE. IN NORTHEASTERN
VENEZUELA...EXPECTING MAXIMA OF 20-30MM. IN COLOMBIA...EXPECTING
ACCUMULATIONS IN THE ORDER OF 10-15MM/DAY AND MAXIMA OF 20-30MM
CONCENTRATING IN CENTRAL AND NORTHWESTERN PARTS OF THE COUNTRY
THROUGH SUNDAY. AN INCREASING TREND IS EXPECTED INTO EARLY NEXT
WEEK AS THE UPPER VENTILATION PATTERN BECOMES MORE FAVORABLE...AND
AS THE PANAMANIAN LOW CIRCULATIONS BECOMES BETTER ORGANIZED. THIS
WILL LEAD TO AN INCREASE TO MAXIMA OF 20-40MM/DAY ON
SUNDAY-MONDAY...AND A FURTHER INCREASE ON MONDAY-TUESDAY.

TROPICAL/EASTERLY WAVES INITIALIZED AT 12UTC:
INITIAL   24     36     48     60     72     84     96       TYPE
25W      29W    33W    37W    41W    45W    49W     52W      TW
40W      43W    46W    50W    54W    58W    62W     66W      TW
47W      50W    53W    57W    61W    65W    69W     73W      TW
85W      88W    92W    94W    96W    98W   100W    102W      TW

A VERY AMPLE TROPICAL WAVE IS INITIALIZED AT 25W...AND TO THE
SOUTH OF 22N. THIS WAVE IS TRAILING BEHIND A SAHARAN AIR LAYER AND
TRADE WIND SURGE...AND IS FORECAST TO REACH FRENCH GUIANA ON
MONDAY. THE WAVE WILL LEAD TO AN INCREASE IN RAINFALL ACROSS THE
EASTERN CARIBBEAN FROM TUESDAY THROUGH WEDNESDAY/THURSDAY.

A SMALL TROPICAL WAVE ALONG 40W REACHES FRENCH GUIANA LATE ON
SATURDAY. THIS WAVE WILL GENERALLY CONFINE TO THE ATLANTIC
ITCZ...AND WILL EXERT MINOR STIMULATING EFFECTS ON RAINFALL IN THE
GUIANAS...AS IT TRAILS CLOSE BEHIND A MUCH LARGER AND ROBUST
TROPICAL WAVE (SEE BELOW).

A LARGE AND ROBUST TROPICAL WAVE EXTENDS ALONG 47W...AND WILL
STIMULATE IN NORTHERN SOUTH AMERICA AND THE CARIBBEAN. THIS WAVE
WILL ARRIVE IN THE GUIANAS ON SATURDAY-SUNDAY WHERE IT WILL FAVOR
TO 15-20MM/DAY AND MAXIMA OF 25-50MM IN INTERACTION WITH THE
ITCZ/NET. DURING SUNDAY-MONDAY...THE WAVE WILL STIMULATE ACTIVITY
ACROSS NORTHEASTERN VENEZUELA WHERE IT WILL SUSTAIN MAXIMA OF...
ACROSS THE SOUTHEASTERN CARIBBEAN...THE WAVE WILL SUSTAIN AMOUNTS
OF 05-10MM/DAY AND MAXIMA OF 15-30MM. ACROSS PUERTO RICO AND THE
VIRGIN ISLANDS THIS WILL SUSTAIN MAXIMA OF 15-25MM.

ANOTHER TROPICAL WAVE IS INITIALIZED AT 85W. THIS WAVE WILL
ENHANCE ACTIVITY MOSTLY ACROSS NORTHERN CENTRAL AMERICA ON
FRIDAY...AND ACROSS MOST OF MEXICO DURING SATURDAY-MONDAY. IN
NORTHERN CENTRAL AMERICA IT WILL INTERACT WITH TUTT-LOW AND THE
ITCZ/NET TO FAVOR MAXIMA OF 30-60MM/DAY FROM NORTHWESTERN
NICARAGUA INTO CHIAPAS/GUATEMALA ON FRIDAY...MAXIMA OF 35-70MM IN
GUATEMALA/CHIAPAS/TABASCO/VERACRUZ AND OAXACA ON
SATURDAY-SUNDAY...AND BY SUNDAY-MONDAY...IT WILL FAVOR MAXIMA OF
75-100 IN SOUTHERN GUERRERO AND SOUTHERN MICHOACAN...MAXIMA OF
25-50MM/DAY IN VERACRUZ...AND MAXIMA OF 20-45MM ALONG THE EJE
VOLCANICO AND SIERRA MADRE ORIENTAL.

GAJADHAR...SLMS (SAINT LUCIA)
GALVEZ/DAVISON...WPC (USA)
$$




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