Home > Products > Valid Products > PMD

000
FXCA20 KWBC 291646
PMDCA

TROPICAL DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1246 PM EDT FRI MAY 29 2015

AT 15 UTC TROPICAL STORM ANDRES CENTERED NEAR 12.5N 114.6W...WITH
MAXIMUM SUSTAINED WINDS OF 60KT AND MINIMUM CENTRAL PRESSURE OF
994 HPA. THE STORM IS MOVING TO THE WEST-NORTHWEST AT 08KT. SEE
NHC BULLETIN FOR OFFICIAL FORECAST.

DISCUSSION FROM MAY 29/12 UTC: MID-LEVEL RIDGE CENTERS TO THE WEST
OF COLIMA/NAYARIT IN MEXICO. THIS IS STEERING TROPICAL STORM
ANDRES TO THE WEST-NORTHWEST. THE NHC IS FORECASTING THIS STORM TO
BECOME A HURRICANE LATER ON FRIDAY. THIS EVOLUTION IS MODULATING
THE ITCZ TO THE NORTH...YET THE ITCZ IS EXPECTED TO REMAIN FAR
OFFSHORE. STILL...CONVECTIVE INSTABILITY HAS INCREASED
SIGNIFICANTLY ACROSS MOST OF THE SOUTHWESTERN COAST OF MEXICO
WHICH WILL BE EXPERIENCING A WET PATTERN THROUGH THE WEEKEND.
EXPECTING ACCUMULATIONS OF 05-10MM/DAY AND MAXIMA OF 15-25MM/DAY
THROUGH THE PERIOD. SOME ENHANCEMENT IS EXPECTED ACROSS
COLIMA/JALISCO/WESTERN MICHOACAN DURING SUNDAY INTO EARLY MONDAY
WITH ISOLATED MAXIMA OF 20-40MM/DAY.

MOISTURE TRANSPORT FROM THE PACIFIC INTO THE SIERRA MADRE
OCCIDENTAL...UNDER INTERACTION WITH BASE OF UPPER TROUGH
APPROACHING THE REGION DURING SATURDAY...WILL LEAD TO AN INCREASE
IN ACTIVITY ALONG THIS REGION. CONVECTION WILL BUILD INTO THE
MOUNTAINS OF NAYARIT/SINALOA DURING SATURDAY WITH RAINFALL MAXIMA
OF 15MM/DAY. ACTIVITY WILL BUILD FURTHER NORTH INTO THE MOUNTAINS
OF SONORA/WESTERN CHIHUAHUA DURING SUNDAY...YET EXPECTING LIGHT
ACCUMULATIONS AS MID-LEVEL RIDGE BUILDS OVER THE REGION.

NORTHEASTERN MEXICO WILL CONTINUE UNDER THE INFLUENCE OF RAPIDLY
MOVING SHORT WAVE PERTURBATIONS AND ASSOCIATED THUNDERSTORMS. A
WELL DEFINED UPPER TROUGH AND ASSOCIATED FRONT WILL ENTER THE
REGION DURING EARLY SATURDAY. ALTHOUGH THE FRONT WILL REMAIN JUST
TO THE NORTH...EXPECTING ENHANCED LOW-LEVEL MOISTURE CONVERGENCE
ESPECIALLY IN INTERACTION WITH THE MOUNTAINS. COOLER AIR ALONG
MID-UPPER TROUGH AXIS WILL ENHANCE INSTABILITY. UPPER TROUGH WILL
ALSO PROVIDE VENTILATION. THIS WILL LEAD TO A PEAK IN ACTIVITY
DURING SATURDAY INTO EARLY HOURS OF SUNDAY...WHEN EXPECTING
ACCUMULATIONS OF 15-20MM/DAY AND MAXIMA OF 25-50MM WITH THE RISK
OF SEVERE CONVECTION. AMOUNTS WILL START DECREASING AFTERWARDS.

AFOREMENTIONED UPPER TROUGH WILL ALSO PLAY A ROLE IN ENHANCING
ACTIVITY ACROSS THE NORTHWESTERN CARIBBEAN/YUCATAN PENINSULA INTO
EARLY NEXT WEEK. TROUGH IS FORECAST TO DIG ACROSS LOUISIANA/GULF
COAST OF MEXICO DURING SUNDAY...AND FURTHER MORE AS IT MEANDERS
SLOWLY EASTWARD TO EXTEND ALONG THE WESTERN GULF OF
MEXICO-TEHUANTEPEC ON MONDAY. THIS WILL ENTER IN PHASE WITH
MOISTURE SURGE ARRIVING FROM THE CARIBBEAN. FURTHERMORE...THE
DEEPENING OF THE UPPER TROUGH AND VENTILATION TO THE SOUTHEAST OF
THE MAIN AXIS WILL ERODE THE CURRENT SUBSIDENCE INVERSION
ESTABLISHED OVER THE NORTHWESTERN CARIBBEAN/NORTHERN CENTRAL
AMERICA. THIS WILL LEAD TO A WET PATTERN DEVELOPING ACROSS
NORTHERN CENTRAL AMERICA/YUCATAN/GULF OF HONDURAS INTO SUNDAY AND
EARLY NEXT WEEK.

A WEAK TUTT-LOW CENTERS TO THE SOUTH OF THE CAYMAN ISLANDS AND IS
INTERACTING WITH AN EAST-WEST FETCH OF CONVECTIVE INSTABILITY THAT
EXTENDS JUST TO THE SOUTH OF CUBA. THIS WILL SUSTAIN ACTIVE
CONVECTION IN THE REGION DURING FRIDAY...WHEN EXPECTING MAXIMA OF
15-25MM/DAY OVER SOUTHEASTERN CUBA...MAXIMA OF 20-35MM/DAY ACROSS
EXTREME WESTERN CUBA...AND MAXIMA OF 15MM/DAY OVER BELIZE/EASTERN
YUCATAN. TUTT WILL GRADUALLY WEAKEN AS IT MEANDERS WESTWARD
TOWARDS THE GULF OF HONDURAS...YET LOCALLY MODERATE AMOUNTS ARE
STILL POSSIBLE. DURING SATURDAY FOCUS OF ACTIVITY WILL EXTEND INTO
NORTHEASTERN YUCATAN WHERE EXPECTING ACCUMULATIONS OF 05-10MM/DAY
AND MAXIMA OF 15-25MM/DAY. HIGHEST AMOUNTS IN THE REGION ARE TO
THEN CONCENTRATE OVER MOST OF NORTHERN YUCATAN DURING SUNDAY INTO
EARLY MONDAY.

TO THE EAST... STRONG PAIR OF TUTT LOWS EXTENDS WELL TO THE NORTH
OF THE GREATER ANTILLES NEAR 28N 61W. THESE ARE INDUCING A PAIR OF
SURFACE TROUGHS...ONE OF WHICH IS CROSSING THE CARIBBEAN EXTENDING
ACROSS HISPANIOLA INTO WESTERN VENEZUELA. ACTIVE CONVECTION IN
NORTHERN SOUTH AMERICA IS ENHANCING THE DEVELOPMENT OF THE
SUBEQUATORIAL RIDGE. AS RIDGE BUILDS WHILE TUTTS WEAKEN AND
MEANDER TO THE NORTH...EXPECTING SOUTHERN TIER OF TUTT-INDUCED
WAVE TO DETACH AND START PROPAGATING WESTWARD ACROSS THE CENTRAL
CARIBBEAN AS EARLY AS SATURDAY MORNING. PRECIPITABLE WATER
ANALYSIS SHOWS A POOL OF DEEP MOISTURE AND DEEP-LAYER CONVECTIVE
INSTABILITY SITTING OVER THE SOUTHEASTERN CARIBBEAN AND NORTHERN
COLOMBIA/VENEZUELA/GUYANA/WINDWARD ISLANDS. THIS MOISTURE POOL IS
FORECAST TO MEANDER WEST/NORTHWESTWARD THROUGH THE CYCLE...LEADING
TO A NOTICEABLE INCREASE IN CONVECTION AND ACCUMULATIONS ACROSS
THE LEEWARD ISLANDS/PUERTO RICO AND THE DOMINICAN REPUBLIC ON
FRIDAY...JAMAICA/HAITI SOUTHEASTERN CUBA AND COSTA RICA ON
SATURDAY...SOUTHEASTERN CUBA/CAYMAN ISLANDS/NICARAGUA/EASTERN
HONDURAS ON SUNDAY...AND ALL OF NORTHERN CENTRAL
AMERICA/BELIZE/YUCATAN AND WESTERN CUBA ON MONDAY. AT UPPER
LEVELS...EXPECTING AN INCREASE IN DIVERGENCE OVER THE
CENTRAL/EASTERN CARIBBEAN INTO THE NORTHEASTERN GREATER ANTILLES
TO PEAK DURING SATURDAY AND SUNDAY IN RESPONSE TO THE
INTENSIFICATION OF THE SUBEQUATORIAL RIDGE. THIS WILL INTERACT
WITH DEEP-LAYER MOISTURE TO ENHANCE THUNDERSTORMS DEVELOPMENT AND
ACCUMULATIONS. ANOTHER SIGNIFICANT FEATURE THAT WILL PLAY AN
IMPORTANT ROLE IN PRECIPITATION IS A TRADE WIND SURGE. THE SURGE
HAS SPEEDS EXCEEDING 20KT AT 950 HPA. THE EDGE OF THE SURGE WILL
EXTEND FROM SOUTHWEST TO NORTHEAST OF A LINE CROSSING
GUADELOUPE/DOMINICA BY FRIDAY EVENING...THE LEEWARD ISLANDS/VIRGIN
ISLANDS BY SATURDAY EVENING...TO EXTEND ALONG JAMAICA-SOUTHERN
HISPANIOLA-PUERTO PLATA/JUST TO THE NORTHWEST OF PUERTO RICO BY
SUNDAY EVENING. THE LEADING EDGE OF THIS SURGE WILL BE ASSOCIATED
WITH AN ENHANCEMENT OF CONVECTION DUE TO ENHANCED LOW-LEVEL
CONVERGENCE. BEHIND THE EDGE OF THIS SURGE HOWEVER...EXPECTING THE
ADVECTION OF A MUCH MORE STABLE AIRMASS THAT WILL LEAD TO A MARKED
DECREASE IN ACTIVITY AS IT MOVES FROM THE TROPICAL NORTH ATLANTIC
INTO CARIBBEAN.

IN TERMS OF ACCUMULATIONS...THROUGH EARLY SATURDAY EXPECTING
LARGEST AMOUNTS OVER PUERTO RICO AND DOMINICAN REPUBLIC WITH
MAXIMA OF 20-45MM/DAY. OVER JAMAICA/HAITI AND THE LEEWARD ISLANDS
EXPECTING MAXIMA OF 15MM/DAY. DURING SATURDAY INTO EARLY SUNDAY
EXPECTING LARGEST AMOUNTS OVER JAMAICA AND HAITI WITH MAXIMA OF
25-50MM/DAY. ACROSS PUERTO RICO/EASTERN HISPANIOLA EXPECTING STILL
MAXIMA OF 20-45MM/DAY. OVER THE LEEWARD ISLANDS EXPECTING MAXIMA
OF 15MM/DAY WITH A WEAKENING TREND AFTERWARDS. DURING SUNDAY INTO
EARLY MONDAY EXPECTING FOCUS OF STRONGEST ACTIVITY OVER JAMAICA
WITH MAXIMA OF 25-50MM/DAY. MODERATE AMOUNTS ARE ALSO EXPECTED
OVER HISPANIOLA AND SOUTHEASTERN CUBA/CAYMAN ISLANDS WITH MAXIMA
OF 20-40MM/DAY.

FURTHER SOUTH...SEASONALLY ACTIVE PATTERN OF CONVECTION IS
DOMINATING EXTREME NORTHERN SOUTH AMERICA AIDED BY THE UPPER
DIVERGENT PHASE OF THE MADDEN-JULIAN OSCILLATION. ACTIVITY IS
ORGANIZING ALONG THE ITCZ AND EMBEDDED PERTURBATIONS...WHICH WILL
ROUGHLY EXTEND OVER THE NORTHERN GUIANAS/NORTH-CENTRAL VENEZUELA
INTO NORTH-CENTRAL COLOMBIA THROUGH THE CYCLE. DURING
FRIDAY...TROUGH PROPAGATING ALONG THE ITCZ WILL ENHANCE ACTIVITY
ACROSS FRENCH GUYANA AND SURINAME TO PRODUCE ACCUMULATIONS OF
10-15MM/DAY AND MAXIMA OF 20-40MM/DAY. ANOTHER REGION OF ENHANCED
CONVECTION WILL CONCENTRATE ACROSS EASTERN/CENTRAL VENEZUELA INTO
TRINIDAD WITH MAXIMA OF 25-50MM/DAY. A THIRD REGION OF ENHANCED
ACTIVITY WILL CONCENTRATED OVER NORTHWESTERN VENEZUELA INTO
NORTHERN COLOMBIA WITH MAXIMA OF 40-80MM/DAY. DURING SATURDAY INTO
EARLY SUNDAY ACTIVITY WILL CONCENTRATE ALONG THREE TROUGHS. ONE
WILL EXTEND ACROSS SURINAME TO ENHANCE DEVELOPMENT AND PRODUCE
MAXIMA OF 20-35MM/DAY IN NORTHERN SURINAME AND FRENCH GUIANA. THE
SECOND TROUGH WILL EXTEND ALONG NORTHEASTERN VENEZUELA TO PRODUCE
MAXIMA OF 25-50MM/DAY. A THIRD REGION OF ENHANCED ACTIVITY WILL
EXTEND OVER THE ANDES OF COLOMBIA INTO LAKE MARACAIBO/WESTERN
VENEZUELA WITH MAXIMA OF 25-50MM/DAY. ON SUNDAY INTO
MONDAY...EXPECTING A SLIGHT DECREASE IN MAXIMA. ENHANCED ACTIVITY
WILL CONCENTRATE OVER THE NORTHERN GUIANAS...BUT ESPECIALLY TO THE
WEST ACROSS MOST OF VENEZUELA/GUYANA WHERE EXPECTING MAXIMA OF
25-50MM/DAY. ACROSS SOUTHERN CENTRAL AMERICA...EXPECTING A GRADUAL
INCREASE IN ACTIVITY FROM EAST TO WEST WITH AMOUNTS INCREASING
FROM MAXIMA OF 15-20MM/DAY TO 20-35MM/DAY BY MONDAY MORNING.

TROPICAL/EASTERLY WAVES INITIALIZED AT 12UTC
INITIAL  24     36     48     60     72     84     96        TYPE

CRAIG...TTMS (TRINIDAD AND TOBAGO)
SAMUEL...MDS (SURINAME)
GALVEZ...WPC (USA)


$$







000
FXCA20 KWBC 291242
PMDCA

TROPICAL DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
842 AM EDT FRI MAY 29 2015

PRELIMINARY DISCUSSION FOR PUERTO RICO AND THE USVI FROM MAY 29 AT
06Z. LARGE TUTT EXTENDS WELL TO THE NORTHEAST OF THE ISLANDS
CENTERING IN TWO LOWS ONE AT 27N 64W AND ANOTHER AT 29N 58W. THE
TUTT IS GRADUALLY MEANDERING TO THE NORTH WHILE WEAKENING...AS THE
SUBEQUATORIAL RIDGE TO THE SOUTH BUILDS INTO THE REGION. THIS IS
ENHANCING UPPER DIVERGENCE...WHICH IS FORECAST TO GRADUALLY
INCREASE TO PEAK DURING THE WEEKEND. AT LOW LEVELS...TUTT INDUCED
WAVE EXTENDS ALONG 70W FROM NORTHERN SOUTH AMERICA INTO 25N
CROSSING HISPANIOLA. OVER THE FORECAST AREA...WINDS ARE RATHER
WEAK WITH SPEEDS IN THE ORDER OF 05-10KT AND FROM THE
SOUTH-SOUTHEAST. AS SOUTHEASTERLIES DOMINATE MOST OF THE EASTERN
CARIBBEAN IN THE EASTERN SIDE OF THE TUTT-INDUCED WAVE...A
WIDESPREAD TRANSPORT OF A BROAD AREA OF TROPICAL MOISTURE AND
INSTABILITY IS UNDERWAY. THIS SURGE IN MOISTURE AND INSTABILITY IS
GRADUALLY INCREASING IN MAGNITUDE UNDER UPPER DIVERGENT PATTERN
BETWEEN TUTT AND SUBEQUATORIAL RIDGE. THIS WILL LEAD TO A FAIRLY
WET PATTERN OVER PUERTO RICO AND THE USVI STARTING FRIDAY
AFTERNOON...PEAKING DURING THE WEEKEND AND SLOWLY WANING INTO
EARLY NEXT WEEK.

MODELS SHOW MOISTURE SURGE ARRIVING DURING FRIDAY AFTERNOON...AND
SO WILL THE ASSOCIATED SCATTERED THUNDERSTORMS. AT UPPER
LEVELS...WINDS ARE TO GRADUALLY BACK FROM WESTERLIES DURING FRIDAY
TO SOUTHWESTERLIES DURING SATURDAY/SUNDAY AS THE SUBEQUATORIAL
RIDGE BUILDS INTO THE REGION. THIS WILL LEAD TO AN INCREASE IN
UPPER DIVERGENCE WHICH WILL INTERACT WITH UNSTABLE AIR MASS TO
ENHANCE THE COVERAGE AND INTENSITY OF THUNDERSTORMS. A TRADE WIND
SURGE IS ALSO UNDERWAY. IT IS EXPECTED TO ARRIVE IN THE REGION
DURING SATURDAY AFTERNOON...WHEN WINDS ARE TO INCREASE TO 15-20KT.
WIND SURGE WILL INITIALLY ENHANCE LOW-LEVEL CONVERGENCE AND THUS
RAINFALL AMOUNTS. EVENTUALLY...HOWEVER...THE SURGE WILL DISPLACE
REGION OF HIGHEST INSTABILITY NORTHWESTWARD LEADING TO DRIER
CONDITIONS INTO EARLY NEXT WEEK. IT APPEARS THAT WET SPELL WILL
DEVELOP THIS AFTERNOON...PEAK DURING LATE FRIDAY-SATURDAY AND
START TO WANE DURING LATE SUNDAY AND AFTER. ALL GLOBAL MODELS ARE
CAPTURING THE GENERAL TREND...BUT THEY DIFFER ON THE DISTRIBUTION
AND TIMING OF PRECIPITATION. THE ECMWF HAS A REASONABLE SOLUTION
AS IT SUGGEST THE HEAVIEST RAINFALL AMOUNTS DURING SATURDAY...WHEN
THE TRADE WIND SURGE CONVERGENCE AND UPPER DIVERGENCE ENTER IN
PHASE. THE GFS IS SUGGESTING A WETTER SOLUTION IN TERMS OF
ACCUMULATIONS AND DURATION OF THE WET EVENT...AS IT DOES NOT
DISPLACE THE REGION OF INSTABILITY AND DEEP LAYER MOISTURE TOO FAR
NORTH...LETTING IT LINGER JUST TO THE NORTH OF THE ISLANDS INTO
THE MEDIUM RANGE PERIOD. IT IS ALSO PLACING MORE WEIGHT ON EARLY
MORNING ACCUMULATIONS OVER THE VI AND SOUTHEASTERN PUERTO RICO
INSTEAD OF AFTERNOON THUNDERSTORMS OVER NORTHWESTERN PUERTO RICO.
THE HIGH RESOLUTION MODELS ARE ALSO SHOWING PRECIPITATION PEAKING
IN NORTHWESTERN PUERTO RICO...WITH THE ARW SHOWING A WETTER
SOLUTION AND MORE WIDESPREAD PRECIPITATION THAN THE NMM.

WE LEAN TOWARDS THE ECMWF SOLUTION AND THE NMM ONE...WHICH DO SHOW
SCATTERED THUNDERSTORM ARRIVING AND DEVELOPING DURING FRIDAY
AFTERNOON INTO EARLY MORNING HOURS ON SUNDAY...AND STRONGER BUT
LESS WIDESPREAD THUNDERSTORMS  ACROSS NORTHWESTERN PUERTO RICO
DURING SATURDAY AFTERNOON. EXPECTING LOCALIZED ACCUMULATIONS OF
2-3 INCHES IN STRONGEST STORMS...WHILE SCATTERED SHOWERS AND
THUNDERSTORMS ARE TO PRODUCE AMOUNTS BETWEEN HALF AND ONE INCH/DAY
ELSEWHERE.

CRAIG...TTMS (TRINIDAD AND TOBAGO)
SAMUEL...MDS (SURINAME)
GALVEZ...WPC (USA)
$$







000
FXCA20 KWBC 291242
PMDCA

TROPICAL DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
842 AM EDT FRI MAY 29 2015

PRELIMINARY DISCUSSION FOR PUERTO RICO AND THE USVI FROM MAY 29 AT
06Z. LARGE TUTT EXTENDS WELL TO THE NORTHEAST OF THE ISLANDS
CENTERING IN TWO LOWS ONE AT 27N 64W AND ANOTHER AT 29N 58W. THE
TUTT IS GRADUALLY MEANDERING TO THE NORTH WHILE WEAKENING...AS THE
SUBEQUATORIAL RIDGE TO THE SOUTH BUILDS INTO THE REGION. THIS IS
ENHANCING UPPER DIVERGENCE...WHICH IS FORECAST TO GRADUALLY
INCREASE TO PEAK DURING THE WEEKEND. AT LOW LEVELS...TUTT INDUCED
WAVE EXTENDS ALONG 70W FROM NORTHERN SOUTH AMERICA INTO 25N
CROSSING HISPANIOLA. OVER THE FORECAST AREA...WINDS ARE RATHER
WEAK WITH SPEEDS IN THE ORDER OF 05-10KT AND FROM THE
SOUTH-SOUTHEAST. AS SOUTHEASTERLIES DOMINATE MOST OF THE EASTERN
CARIBBEAN IN THE EASTERN SIDE OF THE TUTT-INDUCED WAVE...A
WIDESPREAD TRANSPORT OF A BROAD AREA OF TROPICAL MOISTURE AND
INSTABILITY IS UNDERWAY. THIS SURGE IN MOISTURE AND INSTABILITY IS
GRADUALLY INCREASING IN MAGNITUDE UNDER UPPER DIVERGENT PATTERN
BETWEEN TUTT AND SUBEQUATORIAL RIDGE. THIS WILL LEAD TO A FAIRLY
WET PATTERN OVER PUERTO RICO AND THE USVI STARTING FRIDAY
AFTERNOON...PEAKING DURING THE WEEKEND AND SLOWLY WANING INTO
EARLY NEXT WEEK.

MODELS SHOW MOISTURE SURGE ARRIVING DURING FRIDAY AFTERNOON...AND
SO WILL THE ASSOCIATED SCATTERED THUNDERSTORMS. AT UPPER
LEVELS...WINDS ARE TO GRADUALLY BACK FROM WESTERLIES DURING FRIDAY
TO SOUTHWESTERLIES DURING SATURDAY/SUNDAY AS THE SUBEQUATORIAL
RIDGE BUILDS INTO THE REGION. THIS WILL LEAD TO AN INCREASE IN
UPPER DIVERGENCE WHICH WILL INTERACT WITH UNSTABLE AIR MASS TO
ENHANCE THE COVERAGE AND INTENSITY OF THUNDERSTORMS. A TRADE WIND
SURGE IS ALSO UNDERWAY. IT IS EXPECTED TO ARRIVE IN THE REGION
DURING SATURDAY AFTERNOON...WHEN WINDS ARE TO INCREASE TO 15-20KT.
WIND SURGE WILL INITIALLY ENHANCE LOW-LEVEL CONVERGENCE AND THUS
RAINFALL AMOUNTS. EVENTUALLY...HOWEVER...THE SURGE WILL DISPLACE
REGION OF HIGHEST INSTABILITY NORTHWESTWARD LEADING TO DRIER
CONDITIONS INTO EARLY NEXT WEEK. IT APPEARS THAT WET SPELL WILL
DEVELOP THIS AFTERNOON...PEAK DURING LATE FRIDAY-SATURDAY AND
START TO WANE DURING LATE SUNDAY AND AFTER. ALL GLOBAL MODELS ARE
CAPTURING THE GENERAL TREND...BUT THEY DIFFER ON THE DISTRIBUTION
AND TIMING OF PRECIPITATION. THE ECMWF HAS A REASONABLE SOLUTION
AS IT SUGGEST THE HEAVIEST RAINFALL AMOUNTS DURING SATURDAY...WHEN
THE TRADE WIND SURGE CONVERGENCE AND UPPER DIVERGENCE ENTER IN
PHASE. THE GFS IS SUGGESTING A WETTER SOLUTION IN TERMS OF
ACCUMULATIONS AND DURATION OF THE WET EVENT...AS IT DOES NOT
DISPLACE THE REGION OF INSTABILITY AND DEEP LAYER MOISTURE TOO FAR
NORTH...LETTING IT LINGER JUST TO THE NORTH OF THE ISLANDS INTO
THE MEDIUM RANGE PERIOD. IT IS ALSO PLACING MORE WEIGHT ON EARLY
MORNING ACCUMULATIONS OVER THE VI AND SOUTHEASTERN PUERTO RICO
INSTEAD OF AFTERNOON THUNDERSTORMS OVER NORTHWESTERN PUERTO RICO.
THE HIGH RESOLUTION MODELS ARE ALSO SHOWING PRECIPITATION PEAKING
IN NORTHWESTERN PUERTO RICO...WITH THE ARW SHOWING A WETTER
SOLUTION AND MORE WIDESPREAD PRECIPITATION THAN THE NMM.

WE LEAN TOWARDS THE ECMWF SOLUTION AND THE NMM ONE...WHICH DO SHOW
SCATTERED THUNDERSTORM ARRIVING AND DEVELOPING DURING FRIDAY
AFTERNOON INTO EARLY MORNING HOURS ON SUNDAY...AND STRONGER BUT
LESS WIDESPREAD THUNDERSTORMS  ACROSS NORTHWESTERN PUERTO RICO
DURING SATURDAY AFTERNOON. EXPECTING LOCALIZED ACCUMULATIONS OF
2-3 INCHES IN STRONGEST STORMS...WHILE SCATTERED SHOWERS AND
THUNDERSTORMS ARE TO PRODUCE AMOUNTS BETWEEN HALF AND ONE INCH/DAY
ELSEWHERE.

CRAIG...TTMS (TRINIDAD AND TOBAGO)
SAMUEL...MDS (SURINAME)
GALVEZ...WPC (USA)
$$






000
FXCA20 KWBC 291242
PMDCA

TROPICAL DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
842 AM EDT FRI MAY 29 2015

PRELIMINARY DISCUSSION FOR PUERTO RICO AND THE USVI FROM MAY 29 AT
06Z. LARGE TUTT EXTENDS WELL TO THE NORTHEAST OF THE ISLANDS
CENTERING IN TWO LOWS ONE AT 27N 64W AND ANOTHER AT 29N 58W. THE
TUTT IS GRADUALLY MEANDERING TO THE NORTH WHILE WEAKENING...AS THE
SUBEQUATORIAL RIDGE TO THE SOUTH BUILDS INTO THE REGION. THIS IS
ENHANCING UPPER DIVERGENCE...WHICH IS FORECAST TO GRADUALLY
INCREASE TO PEAK DURING THE WEEKEND. AT LOW LEVELS...TUTT INDUCED
WAVE EXTENDS ALONG 70W FROM NORTHERN SOUTH AMERICA INTO 25N
CROSSING HISPANIOLA. OVER THE FORECAST AREA...WINDS ARE RATHER
WEAK WITH SPEEDS IN THE ORDER OF 05-10KT AND FROM THE
SOUTH-SOUTHEAST. AS SOUTHEASTERLIES DOMINATE MOST OF THE EASTERN
CARIBBEAN IN THE EASTERN SIDE OF THE TUTT-INDUCED WAVE...A
WIDESPREAD TRANSPORT OF A BROAD AREA OF TROPICAL MOISTURE AND
INSTABILITY IS UNDERWAY. THIS SURGE IN MOISTURE AND INSTABILITY IS
GRADUALLY INCREASING IN MAGNITUDE UNDER UPPER DIVERGENT PATTERN
BETWEEN TUTT AND SUBEQUATORIAL RIDGE. THIS WILL LEAD TO A FAIRLY
WET PATTERN OVER PUERTO RICO AND THE USVI STARTING FRIDAY
AFTERNOON...PEAKING DURING THE WEEKEND AND SLOWLY WANING INTO
EARLY NEXT WEEK.

MODELS SHOW MOISTURE SURGE ARRIVING DURING FRIDAY AFTERNOON...AND
SO WILL THE ASSOCIATED SCATTERED THUNDERSTORMS. AT UPPER
LEVELS...WINDS ARE TO GRADUALLY BACK FROM WESTERLIES DURING FRIDAY
TO SOUTHWESTERLIES DURING SATURDAY/SUNDAY AS THE SUBEQUATORIAL
RIDGE BUILDS INTO THE REGION. THIS WILL LEAD TO AN INCREASE IN
UPPER DIVERGENCE WHICH WILL INTERACT WITH UNSTABLE AIR MASS TO
ENHANCE THE COVERAGE AND INTENSITY OF THUNDERSTORMS. A TRADE WIND
SURGE IS ALSO UNDERWAY. IT IS EXPECTED TO ARRIVE IN THE REGION
DURING SATURDAY AFTERNOON...WHEN WINDS ARE TO INCREASE TO 15-20KT.
WIND SURGE WILL INITIALLY ENHANCE LOW-LEVEL CONVERGENCE AND THUS
RAINFALL AMOUNTS. EVENTUALLY...HOWEVER...THE SURGE WILL DISPLACE
REGION OF HIGHEST INSTABILITY NORTHWESTWARD LEADING TO DRIER
CONDITIONS INTO EARLY NEXT WEEK. IT APPEARS THAT WET SPELL WILL
DEVELOP THIS AFTERNOON...PEAK DURING LATE FRIDAY-SATURDAY AND
START TO WANE DURING LATE SUNDAY AND AFTER. ALL GLOBAL MODELS ARE
CAPTURING THE GENERAL TREND...BUT THEY DIFFER ON THE DISTRIBUTION
AND TIMING OF PRECIPITATION. THE ECMWF HAS A REASONABLE SOLUTION
AS IT SUGGEST THE HEAVIEST RAINFALL AMOUNTS DURING SATURDAY...WHEN
THE TRADE WIND SURGE CONVERGENCE AND UPPER DIVERGENCE ENTER IN
PHASE. THE GFS IS SUGGESTING A WETTER SOLUTION IN TERMS OF
ACCUMULATIONS AND DURATION OF THE WET EVENT...AS IT DOES NOT
DISPLACE THE REGION OF INSTABILITY AND DEEP LAYER MOISTURE TOO FAR
NORTH...LETTING IT LINGER JUST TO THE NORTH OF THE ISLANDS INTO
THE MEDIUM RANGE PERIOD. IT IS ALSO PLACING MORE WEIGHT ON EARLY
MORNING ACCUMULATIONS OVER THE VI AND SOUTHEASTERN PUERTO RICO
INSTEAD OF AFTERNOON THUNDERSTORMS OVER NORTHWESTERN PUERTO RICO.
THE HIGH RESOLUTION MODELS ARE ALSO SHOWING PRECIPITATION PEAKING
IN NORTHWESTERN PUERTO RICO...WITH THE ARW SHOWING A WETTER
SOLUTION AND MORE WIDESPREAD PRECIPITATION THAN THE NMM.

WE LEAN TOWARDS THE ECMWF SOLUTION AND THE NMM ONE...WHICH DO SHOW
SCATTERED THUNDERSTORM ARRIVING AND DEVELOPING DURING FRIDAY
AFTERNOON INTO EARLY MORNING HOURS ON SUNDAY...AND STRONGER BUT
LESS WIDESPREAD THUNDERSTORMS  ACROSS NORTHWESTERN PUERTO RICO
DURING SATURDAY AFTERNOON. EXPECTING LOCALIZED ACCUMULATIONS OF
2-3 INCHES IN STRONGEST STORMS...WHILE SCATTERED SHOWERS AND
THUNDERSTORMS ARE TO PRODUCE AMOUNTS BETWEEN HALF AND ONE INCH/DAY
ELSEWHERE.

CRAIG...TTMS (TRINIDAD AND TOBAGO)
SAMUEL...MDS (SURINAME)
GALVEZ...WPC (USA)
$$







000
FXCA20 KWBC 291242
PMDCA

TROPICAL DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
842 AM EDT FRI MAY 29 2015

PRELIMINARY DISCUSSION FOR PUERTO RICO AND THE USVI FROM MAY 29 AT
06Z. LARGE TUTT EXTENDS WELL TO THE NORTHEAST OF THE ISLANDS
CENTERING IN TWO LOWS ONE AT 27N 64W AND ANOTHER AT 29N 58W. THE
TUTT IS GRADUALLY MEANDERING TO THE NORTH WHILE WEAKENING...AS THE
SUBEQUATORIAL RIDGE TO THE SOUTH BUILDS INTO THE REGION. THIS IS
ENHANCING UPPER DIVERGENCE...WHICH IS FORECAST TO GRADUALLY
INCREASE TO PEAK DURING THE WEEKEND. AT LOW LEVELS...TUTT INDUCED
WAVE EXTENDS ALONG 70W FROM NORTHERN SOUTH AMERICA INTO 25N
CROSSING HISPANIOLA. OVER THE FORECAST AREA...WINDS ARE RATHER
WEAK WITH SPEEDS IN THE ORDER OF 05-10KT AND FROM THE
SOUTH-SOUTHEAST. AS SOUTHEASTERLIES DOMINATE MOST OF THE EASTERN
CARIBBEAN IN THE EASTERN SIDE OF THE TUTT-INDUCED WAVE...A
WIDESPREAD TRANSPORT OF A BROAD AREA OF TROPICAL MOISTURE AND
INSTABILITY IS UNDERWAY. THIS SURGE IN MOISTURE AND INSTABILITY IS
GRADUALLY INCREASING IN MAGNITUDE UNDER UPPER DIVERGENT PATTERN
BETWEEN TUTT AND SUBEQUATORIAL RIDGE. THIS WILL LEAD TO A FAIRLY
WET PATTERN OVER PUERTO RICO AND THE USVI STARTING FRIDAY
AFTERNOON...PEAKING DURING THE WEEKEND AND SLOWLY WANING INTO
EARLY NEXT WEEK.

MODELS SHOW MOISTURE SURGE ARRIVING DURING FRIDAY AFTERNOON...AND
SO WILL THE ASSOCIATED SCATTERED THUNDERSTORMS. AT UPPER
LEVELS...WINDS ARE TO GRADUALLY BACK FROM WESTERLIES DURING FRIDAY
TO SOUTHWESTERLIES DURING SATURDAY/SUNDAY AS THE SUBEQUATORIAL
RIDGE BUILDS INTO THE REGION. THIS WILL LEAD TO AN INCREASE IN
UPPER DIVERGENCE WHICH WILL INTERACT WITH UNSTABLE AIR MASS TO
ENHANCE THE COVERAGE AND INTENSITY OF THUNDERSTORMS. A TRADE WIND
SURGE IS ALSO UNDERWAY. IT IS EXPECTED TO ARRIVE IN THE REGION
DURING SATURDAY AFTERNOON...WHEN WINDS ARE TO INCREASE TO 15-20KT.
WIND SURGE WILL INITIALLY ENHANCE LOW-LEVEL CONVERGENCE AND THUS
RAINFALL AMOUNTS. EVENTUALLY...HOWEVER...THE SURGE WILL DISPLACE
REGION OF HIGHEST INSTABILITY NORTHWESTWARD LEADING TO DRIER
CONDITIONS INTO EARLY NEXT WEEK. IT APPEARS THAT WET SPELL WILL
DEVELOP THIS AFTERNOON...PEAK DURING LATE FRIDAY-SATURDAY AND
START TO WANE DURING LATE SUNDAY AND AFTER. ALL GLOBAL MODELS ARE
CAPTURING THE GENERAL TREND...BUT THEY DIFFER ON THE DISTRIBUTION
AND TIMING OF PRECIPITATION. THE ECMWF HAS A REASONABLE SOLUTION
AS IT SUGGEST THE HEAVIEST RAINFALL AMOUNTS DURING SATURDAY...WHEN
THE TRADE WIND SURGE CONVERGENCE AND UPPER DIVERGENCE ENTER IN
PHASE. THE GFS IS SUGGESTING A WETTER SOLUTION IN TERMS OF
ACCUMULATIONS AND DURATION OF THE WET EVENT...AS IT DOES NOT
DISPLACE THE REGION OF INSTABILITY AND DEEP LAYER MOISTURE TOO FAR
NORTH...LETTING IT LINGER JUST TO THE NORTH OF THE ISLANDS INTO
THE MEDIUM RANGE PERIOD. IT IS ALSO PLACING MORE WEIGHT ON EARLY
MORNING ACCUMULATIONS OVER THE VI AND SOUTHEASTERN PUERTO RICO
INSTEAD OF AFTERNOON THUNDERSTORMS OVER NORTHWESTERN PUERTO RICO.
THE HIGH RESOLUTION MODELS ARE ALSO SHOWING PRECIPITATION PEAKING
IN NORTHWESTERN PUERTO RICO...WITH THE ARW SHOWING A WETTER
SOLUTION AND MORE WIDESPREAD PRECIPITATION THAN THE NMM.

WE LEAN TOWARDS THE ECMWF SOLUTION AND THE NMM ONE...WHICH DO SHOW
SCATTERED THUNDERSTORM ARRIVING AND DEVELOPING DURING FRIDAY
AFTERNOON INTO EARLY MORNING HOURS ON SUNDAY...AND STRONGER BUT
LESS WIDESPREAD THUNDERSTORMS  ACROSS NORTHWESTERN PUERTO RICO
DURING SATURDAY AFTERNOON. EXPECTING LOCALIZED ACCUMULATIONS OF
2-3 INCHES IN STRONGEST STORMS...WHILE SCATTERED SHOWERS AND
THUNDERSTORMS ARE TO PRODUCE AMOUNTS BETWEEN HALF AND ONE INCH/DAY
ELSEWHERE.

CRAIG...TTMS (TRINIDAD AND TOBAGO)
SAMUEL...MDS (SURINAME)
GALVEZ...WPC (USA)
$$






    US Dept of Commerce
    National Oceanic and Atmospheric Administration
    National Weather Service
    1325 East West Highway
    Silver Spring, MD 20910
    Page Author: NWS Internet Services Team
Disclaimer
Information Quality
Credits
Glossary
Privacy Policy
Freedom of Information Act (FOIA)
About Us
Career Opportunities