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Tropical Discussion
 
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TROPICAL DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
231 PM EDT THU AUG 21 2014

DISCUSSION FROM AUGUST 20/00UTC: FORECAST PERIOD STARTS WITH UPPER
RIDGE ACROSS NORTHERN/NORTHWESTERN MEXICO AND TUTT TO ITS
SOUTHEAST OVER TAMAULIPAS/NORTHERN VERACRUZ. BOTH SYSTEMS ARE TO
SLOWLY RETROGRESS...WITH RIDGE DOMINATING BAJA CALIFORNIA
SUR-CHIHUAHUA BY FRIDAY EVENING WHILE TUTT CENTERS OVER SOUTHERN
COAHUILA/SAN LUIS POTOSI BY FRIDAY EVENING/EARLY SATURDAY AND THEN
MOVING LITTLE. THESE SYSTEMS WILL SUSTAIN GOOD
VENTILATION...ESPECIALLY IN THEIR PERIPHERY...TO SUSTAIN SEASONAL
DIURNAL CONVECTION ESPECIALLY ALONG THE SIERRA MADRE OCCIDENTAL
AND WEST-CENTRAL MEXICO. AT LOW-LEVELS...BEST MOISTURE CONVERGENCE
AND CONVECTIVE INSTABILITY WILL EXTEND FROM THE CENTRAL MOUNTAINS
OF MEXICO INTO JALISCO/NAYARIT/ZACATECAS AND THEN NORTHWEST INTO
SOUTHEASTERN SONORA AND CHIHUAHUA. OTHER ACTIVE REGION WILL BE THE
SOUTHERN COAST/SIERRA MADRE DEL SUR AS A ROBUST TROPICAL
WAVE/BROAD LOW CROSS TO THE SOUTH. THROUGH FRIDAY
MORNING...EXPECTING LARGEST AMOUNTS ACROSS THE NORTHERN SIERRA
MADRE OCCIDENTAL AND THE SIERRA MADRE DEL SUR WITH MAXIMA OF
40-80MM. ACROSS THE CENTRAL SIERRA MADRE EXPECTING MAXIMA OF
25-50MM. BY FRIDAY THROUGH SATURDAY MORNING...EXPECTING MAXIMA OF
35-70MM/DAY ALONG GUERRERO-MICHOACAN INTO NAYARIT/JALISCO. AMOUNTS
IN THE SIERRA MADRE OCCIDENTAL ARE TO DECREASE TO MAXIMA OF
20-40MM. IN YUCATAN...A WEAK PERTURBATION IN THE TRADES WILL
ENHANCE DIURNAL THUNDERSTORMS PRODUCING MAXIMA OF 20-30MM/DAY.
FROM SATURDAY INTO EARLY SUNDAY...EXPECTING MAXIMA OF 20-50MM/DAY
EXTENDING FROM GUERRERO-MICHOACAN INTO SINALOA.

ACTIVITY OVER CENTRAL AMERICA WILL BE MODULATED BY TUTT LOW MOVING
IN FROM THE CARIBBEAN. THE TUTT WILL CENTER OVER NORTHEASTERN
NICARAGUA BY THURSDAY EVENING...SOUTHERN HONDURAS BY FRIDAY
EVENING AND WESTERN EL SALVADOR BY SATURDAY EVENING. BEST
VENTILATION WILL BE IN THE SOUTHERN AND EASTERN PERIPHERY OF THE
TUTT. AT LOW-LEVELS...WINDS ARE TO GRADUALLY BACK TO
NORTH-NORTHEASTERLIES UNDER INFLUENCE OF TRADE-WIND PERTURBATION
IN THE CENTRAL/EASTERN CARIBBEAN. THIS WILL SUSTAIN LOCALLY HIGHER
AMOUNTS IN NORTHERN AND NORTHEASTERN COASTS FROM HONDURAS TO
PANAMA. THROUGH EARLY FRIDAY...EXPECTING MAXIMA OF 20-40MM/DAY
ACROSS PANAMA/COSTA RICA AND EL SALVADOR/SOUTHERN GUATEMALA. BY
FRIDAY-EARLY SATURDAY...EXPECTING MAXIMA OF 25-50MM/DAY ACROSS
PANAMA...AND 20-40MM/DAY ACROSS COSTA RICA. BY
SATURDAY-SUNDAY...EXPECTING MAXIMA OF 25-50MM/DAY EXTENDING INTO
COSTA RICA.

AREAS TO THE EAST WILL BE UNDER THE INFLUENCE OF A LARGE
PERTURBATION IN THE TRADE WINDS THAT IS ENTERING THE EASTERN
CARIBBEAN. ACROSS CUBA...SCATTERED DIURNAL THUNDERSTORMS WILL
PRODUCE LOCALIZED MAXIMA OF 15-25MM/DAY ON THURSDAY EVENING. MORE
ISOLATED ACTIVITY IS EXPECTED ON FRIDAY. CONDITIONS ARE TO CHANGE
ON THE SOUTHEASTERN PORTION OF THE ISLAND ON SATURDAY...AS TRADE
WIND PERTURBATION APPROACHES FROM THE TURKS AND CAICOS. THIS
SHOULD LEAD TO NORTHERLY WINDS THAT WILL ENHANCE ACCUMULATIONS IN
NORTHEASTERN SLOPES. EXPECTING AMOUNTS OF 15-20MM/DAY WITH
ISOLATED MAXIMA OF 30-60MM. ACROSS THE BAHAMAS...DEPENDING UPON
TRACK OF PERTURBATION...HEAVY RAINS WILL EXTEND FROM THE TURKS AND
CAICOS INTO THE CENTRAL BAHAMAS ON SATURDAY. EXPECTING AMOUNTS OF
25-50MM/DAY AND MAXIMA OF 75-100MM.

PERTURBATION WILL DOMINATE PRECIPITATION ACROSS THE EASTERN
CARIBBEAN. DURING THURSDAY-EARLY FRIDAY...LARGEST AMOUNTS ARE
EXPECTED OVER THE NORTHERN FRENCH ANTILLES-LEEWARD
ISLANDS-VI-EASTERN PUERTO RICO...WHERE EXPECTING MAXIMUM
ACCUMULATIONS OF 50-100MM. ACROSS THE SOUTHERN LESSER ANTILLES
EXPECTING 10-15MM/DAY AND MAXIMA OF 20-40MM. DURING FRIDAY-EARLY
SATURDAY...EXPECTING STRONGEST CONVECTION TO DEVELOP FROM
NORTHWESTERN PUERTO RICO INTO THE CANAL DE LA MONA AND THE
NORTHEASTERN DOMINICAN REPUBLIC...AND CORDILLERA CENTRAL.
THERE...EXPECTING ACCUMULATIONS OF 25-50MM/DAY WITH MAXIMA OF
75-125MM. ACROSS THE NORTHERN LESSER ANTILLES AND PUERTO
RICO...FEEDER BAND CONVERGENCE WILL LEAD TO MAXIMUM ACCUMULATIONS
OF 20-40MM. ON SATURDAY-EARLY SUNDAY...LOW-LEVEL SOUTHERLIES WILL
ENHANCE MOISTURE CONVERGENCE ALONG THE SOUTHERN SLOPES OF
HISPANIOLA...ESPECIALLY OVER THE DOMINICAN REPUBLIC. EXPECTING
ACCUMULATIONS OF 15-20MM/DAY AND ISOLATED MAXIMA OF 30-60MM. OVER
PUERTO RICO EXPECTING MAXIMA OF 20-30MM.

WEATHER CONDITIONS ACROSS NORTHERN SOUTH AMERICA WILL ALSO BE
INFLUENCE BY PERTURBATION IN THE TRADES. DURING THURSDAY...STRONG
MOISTURE CONVERGENCE WILL PRODUCE LARGEST AMOUNTS ACROSS
NORTHEASTERN VENEZUELA INTO TRINIDAD AND WINDWARD ISLANDS...WHERE
EXPECTING MAXIMA OF 25-50MM/DAY. OTHER ACTIVE REGION WILL BE
WESTERN COLOMBIA WHERE EXPECTING MAXIMA OF 30-60MM/DAY. ACROSS
WESTERN VENEZUELA AND THE LAKE MARACAIBO REGION...SEASONAL
CONVECTION WILL LEAD TO MAXIMA OF 15-25MM. ON FRIDAY-EARLY
SATURDAY...STRONG CONVECTION WILL CONCENTRATE ACROSS CENTRAL
VENEZUELA AND INCLUDING COASTAL REGIONS...WHERE EXPECTING MAXIMA
OF 25-50MM/DAY. ACROSS NORTHERN/WESTERN COLOMBIA AND WESTERN
VENEZUELA EXPECTING SIMILAR AMOUNTS. DURING SATURDAY-EARLY
SUNDAY...EXPECTING LARGEST AMOUNTS ACROSS WESTERN VENEZUELA AND
EASTERN/NORTHERN COLOMBIA...WITH ACCUMULATIONS OF 15-20MM/DAY AND
MAXIMA OF 35-70MM. SIMILAR AMOUNTS ARE EXPECTED ACROSS NORTHERN
COLOMBIA AND THE LAKE MARACAIBO REGION.

TROPICAL/EASTERLY WAVES INITIALIZED AT 12UTC
INITIAL  24     36     48     60     72     84     96     TYPE
56W     60W    65W    69W    73W    75W    78W   DISS      TW
97W     98W    101W   103W   106W   108W  109W   110W      TW

A LARGE TROPICAL WAVE IS INITIALIZED AT 56W. THIS WAVE HAS A
MOISTURE POOL WITH PWAT EXCEEDING 65MM AND IS MOVING VERY RAPIDLY
INTO THE EASTERN CARIBBEAN. THE WAVE WILL CROSS THE LEEWARD
ISLANDS/VI TODAY WHERE IT WILL LEAD TO ISOLATED MAXIMA OF
50-100MM/DAY. THE WAVE WILL ALSO ENHANCE ACTIVITY ACROSS
NORTHEASTERN VENEZUELA AND GUYANA. DURING FRIDAY...WAVE WILL CROSS
INTO HISPANIOLA AND CENTRAL VENEZUELA. IT WILL LEAD TO MAXIMUM
ACCUMULATIONS OF 75-125MM/DAY ACROSS NORTHWESTERN PUERTO RICO AND
EASTERN/NORTHEASTERN DOMINICAN REPUBLIC...AND THE CORDILLERA
CENTRAL. DURING SATURDAY INTO SUNDAY...WAVE WILL CONCENTRATE OVER
HISPANIOLA AND THE TURKS AND CAICOS...AND WESTERN
VENEZUELA/EASTERN COLOMBIA. LARGEST AMOUNTS ARE EXPECTED ACROSS
THE TURKS AND CAICOS/SOUTHEASTERN BAHAMAS WITH MAXIMA OF
50-100MM/DAY. ACROSS HISPANIOLA...EXPECTING MAXIMA OF 25-50MM/DAY
IN THE SOUTHERN SLOPES OF THE DOMINICAN REPUBLIC. ACROSS NORTHERN
COLOMBIA/WESTERN VENEZUELA EXPECTING MAXIMA OF 35-70MM/DAY.

TROPICAL WAVE ALONG 97W HAS FORMED A BROAD CIRCULATION ACROSS THE
PACIFIC. THIS WAVE WILL CONTINUE ENHANCING ACTIVITY ACROSS
SOUTHERN MEXICO AS IT PROGRESSES WESTWARD.

VALVERDE...IMN (COSTA RICA)
MEDINA...ONAMET (REPUBLICA DOMINICANA)
DAVISON...WPC(USA)
GALVEZ...WPC(USA)