Prognostic Meteorological Discussion
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FXCA20 KWBC 261540
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TROPICAL DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1139 AM EDT FRI MAY 26 2017

LAST NO AMENDS...NEXT BULLETIN MAY 30.

TROPICAL DISCUSSION FROM MAY 26/12 UTC: POLAR TROUGH EXITED THE
EASTERN USA EARLY IN THE CYCLE...AND THROUGH SATURDAY MORNING IT
IS EXPECTED TO RAPIDLY PULL TO THE NORTHEAST WHILE LIFTING OVER A
BROAD RIDGE TO THE EAST. AT LOW LEVELS ASSOCIATED SURFACE FRONT IS
LOSING UPPER LEVEL SUPPORT...AND IT IS FORECAST TO FRONTOLIZE
LATER TODAY AS IT MEANDERS JUST NORTH OF THE NORTHWEST BAHAMAS.
MEANWHILE...UNDER INFLUENCE OF THE MID/UPPER LEVEL TROUGH...SOME
RESIDUAL CONVECTION IS EXPECTED OVER THE NORTHWEST BAHAMAS AND
WESTERN CUBA DURING THE DAY TODAY...TO FAVOR RAINFALL AMOUNTS OF
05-10MM/DAY AND MAXIMA OF 15MM.

NEXT POLAR TROUGH MOVES ACROSS THE CENTRAL USA ON SUNDAY TO
MONDAY. THE ASSOCIATED FRONT MOVES ACROSS THE CENTRAL USA TO TEXAS
EARLY ON MONDAY MORNING...INTO THE NORTHEAST STATES OF MEXICO
LATER IN THE DAY. AS IT MOVES ACROSS TEXAS THIS WILL SUSTAIN A
PREFRONTAL TROUGH ACROSS NORTHEAST MEXICO... WHERE IT WILL ENHANCE
LOW LEVEL MOISTURE CONVERGENCE. ON SUNDAY THIS WILL RESULT IN
RAINFALL AMOUNTS OF 10-15MM/DAY AND MAXIMA OF 20-35MM. THROUGH
MONDAY ACTIVITY INTENSIFIES ACROSS TAMAULIPAS/VERACRUZ...WITH
RAINFALL AMOUNTS OF 15-20MM/DAY AND MAXIMA OF 40-80MM.

SIMULTANEOUSLY...THE MODELS FORECAST A MID LEVEL RIDGE TO
GRADUALLY BUILD ACROSS THE NORTHERN STATES OF MEXICO/THE GULF TO
THE SOUTHEAST USA...TO ANCHOR AT 500 HPA ON A CLOSED HIGH JUST
SOUTH OF LOUISIANA/MISSISSIPPI LATER ON SATURDAY-SUNDAY. AS THE
RIDGE CONFINES TO THE NORTHERN GULF/NORTHERN STATES OF MEXICO...A
WEAKNESS IN THE HEIGHT FIELD IS TO PERSIST OVER THE SOUTHERN
STATES OF MEXICO/NORTHERN CENTRAL AMERICA... WITH MODELS SHOWING
AN INVERTED TROUGH EXTENDING NORTH FROM THE EASTERN TROPICAL
PACIFIC TO GUATEMALA/SOUTHERN MEXICO DURING THE NEXT 72-84 HRS.
THIS IS TO THEN FAVOR A CONVECTIVELY UNSTABLE AIR MASS DURING THE
NEXT FEW DAYS. THIS...IN COMBINATION WITH TROPICAL WAVES STREAMING
ACROSS THE EASTERN PACIFIC...IS TO SUSTAIN A SURGE IN CONVECTION.
ON THE SOUTHERN STATES OF MEXICO EXPECTING RAINFALL AMOUNTS OF
20-30MM/DAY AND MAXIMA OF 40-80MM EARLY IN THE CYCLE...GRADUALLY
INCREASING TO 35-50MM/DAY AND MAXIMA OF 75-150MM ON SUNDAY TO
MONDAY WHILE GRADUALLY SHIFTING TO GUERRERO/OAXACA AND THE SIERRA
MADRE DEL SUR. ON MONDAY MAXIMA IN THIS AREA WILL PEAK AT
125-250MM. OVER SOUTHERN GUATEMALA-SOUTHERN HONDURAS/EL
SALVADOR-GULF OF FONSECA CONVECTION GRADUALLY BECOMES MORE
ACTIVE/BETTER ORGANIZED...WITH RAINFALL AMOUNTS OF 20-30MM/DAY AND
MAXIMA OF 40-80MM ON FRIDAY TO SATURDAY MORNING. ON SATURDAY
EXPECTING ACCUMULATION OF 15-20MM/DAY AND MAXIMA OF
30-60MM...DECREASING TO 05-10MM/DAY AND MAXIMA OF 15-25MM ON
SUNDAY TO MONDAY. OVER NICARAGUA/NORTHEAST HONDURAS INITIALLY
EXPECTING RAINFALL AMOUNTS OF 10-15MM/DAY AND MAXIMA OF 20-45MM.
THROUGH SUNDAY THIS DECREASES AS A DRYER AIR MASS ENTRAINS FROM
THE EAST. ACROSS COSTA RICA-PANAMA EXPECT RAINFALL AMOUNTS OF
15-20MM/DAY AND MAXIMA OF 30-60MM DURING THE NEXT FOUR DAYS AS
ENHANCED BY THE ITCZ.

ALSO AT 500 HPA...A SHORT WAVE RIDGE OVER THE WESTERN CARIBBEAN
FAVORS THE SOUTHWARD AMPLIFICATION OF A TUTT ACROSS THE EASTERN
CARIBBEAN ISLES. THE TUTT ANCHORS ON A CLOSED LOW TO THE
EAST-NORTHEAST OF THE NORTHERN LEEWARD ISLANDS. THE TUTT PATTERN
WILL HOLD NEARLY UNCHANGED THROUGH MIDDAY ON SATURDAY...THEN
GRADUALLY FILLS TO AN OPEN TROUGH EARLY ON SUNDAY. REMNANTS OF THE
TUTT WILL THEN LIFT TO THE NORTHEAST AS A SHORT WAVE TROUGH
AMPLIFIES ACROSS THE WESTERN ATLANTIC TO THE NORTHERN CARIBBEAN
ISLES DURING THE WEEKEND. AT LOW LEVELS THE TUTT ALOFT FAVORS THE
GENERATION OF PERTURBATIONS IN THE EASTERLY TRADES...WITH MODEL
ANALYSIS/FORECAST SHOWING A COUPLE OF WAVES STREAMING ACROSS THE
NORTHEAST CARIBBEAN OVER THE NEXT COUPLE OF DAYS. AS THEY MEANDER
WEST THESE ARE TO ENHANCE LOW LEVEL MOISTURE CONVERGENCE. AS A
RESULT...PWAT CONTENT WILL GRADUALLY INCREASE TO AROUND 30-35MM
OVER THE NEXT DAY OR SO. ACROSS THE LEEWARD/VIRGIN ISLES THIS IS
TO FAVOR MOSTLY LIGHT CONVECTION WITH ACCUMULATION OF 00-05MM/DAY
AND MAXIMA OF 10MM. ACROSS PUERTO RICO TO HISPANIOLA THIS WILL
RESULT IN RAINFALL AMOUNTS OF 05-10MM/DAY AND MAXIMA OF
15MM...WITH LOCALIZED MAXIMA OF 75-125MM POSSIBLE AS TUTT ALOFT
ENHANCES EFFECTS OF SEA BREEZE CONVERGENCE OVER WESTERN PUERTO
RICO AND CENTRAL HISPANIOLA.

FARTHER SOUTH...ITCZ RELATED CONVERGENCE OVER THE NORTHERN GUIANAS
WILL SUSTAIN  RAINFALL AMOUNTS OF 05-10MM/DAY AND MAXIMA OF
15-25MM...WITH LOCALLY HIGHER AMOUNTS LIKELY AS TROPICAL WAVES
PROPAGATE ALONG THE ITCZ TO THE NORTH (SEE BELOW). OVER VENEZUELA
AND EASTERN COLOMBIA EXPECTING RAINFALL AMOUNTS OF 10-15MM/DAY AND
MAXIMA OF 20-30MM. THROUGH SUNDAY THE MAXIMA INCREASES TO 20-45MM.
HIGHER AMOUNTS ARE FORECAST ACROSS THE EJE CAFETERO IN
NORTHWESTERN COLOMBIA...WHERE UNDER INFLUENCE OF THE PANAMANIAN
LOW EXPECTING RAINFALL ACCUMULATION OF 15-20MM/DAY AND MAXIMA OF
30-60MM.

TROPICAL/EASTERLY WAVES INITIALIZED AT 12UTC:
INITIAL   24     36     48     60     72     84     96       TYPE
35W      37W    40W    43W    47W    50W    53W     56W      TW
49W      52W    56W    58W    61W    64W    68W     70W      TW
55W      58W    62W    DISSIPATES                            EW
67W      69W    71W    74W    77W    79W    81W     83W      TW
81W      83W    86W    89W    92W    95W    97W     99W      EW
90W      93W    95W    98W   101W    DISSIPATES              EW

TROPICAL WAVE IS INITIALIZED ALONG 35W AND TO THE SOUTH OF 10N.
THE WAVE REACHES EASTERN FRENCH GUIANA/AMAPA IN BRASIL LATER ON
SUNDAY...WHERE IN INTERACTION WITH THE ITCZ IT IS TO TRIGGER
RAINFALL AMOUNTS OF 05-10MM/DAY AND MAXIMA OF 15-25MM. AS IT MOVES
ACROSS SURINAME TO GUIANA ON MONDAY IT INCREASES TO 10-15MM/DAY
AND MAXIMA OF 20-30MM.

A TROPICAL WAVE IS INITIALIZED ALONG 49W AND TO THE SOUTH OF 17N.
IT MOVES ACROSS FRENCH GUIANA TO SURINAME LATER TODAY/EARLY
SATURDAY MORNING...TO FAVOR RAINFALL AMOUNTS OF 05-10MM/DAY AND
MAXIMA OF 15-25MM. ACTIVITY THEN SPREADS INTO EASTERN
VENEZUELA/SOUTHERN WINDWARD ISLES ON SATURDAY-SUNDAY MORNING.
ACROSS VENEZUELA IT WILL SUSTAIN RAINFALL AMOUNTS OF 10-15MM/DAY
AND MAXIMA OF 20-30MM...WHILE OVER TRINIDAD AND THE WINDWARD ISLES
EXPECTING ACCUMULATION OF 05-10MM/DAY AND MAXIMA OF 15MM. THIS IS
TO THEN INTERACT WITH DEEPENING TROUGH OVER THE NORTHEAST
CARIBBEAN TO SUSTAIN A PLUME OF TROPICAL MOISTURE ACROSS THE
ISLAND CHAIN ON SUNDAY-MONDAY...WHERE IT WILL RESULT IN RAINFALL
AMOUNTS OF 05-10MM/DAY AND MAXIMA OF 15-25MM. THROUGH MONDAY THIS
INCREASES TO 10-15MM/DAY AND MAXIMA OF 20-45MM...WITH MOST INTENSE
OVER THE FRENCH AND LEEWARD ISLANDS.

AN EASTERLY WAVE ALONG 55W AND SOUTH OF 14N MOVES ACROSS SURINAME
TO GUYANA EARLY IN THE CYCLE...TO TRIGGER RAINFALL AMOUNTS OF
10-15MM/DAY AND MAXIMA OF 20-35MM. AS IT ENTERS EASTERN VENEZUELA
ON SATURDAY THE WAVE IS FORECAST TO DISSIPATE.

A TROPICAL WAVE ALONG 67W AND TO THE SOUTH OF 07N CONTINUES TO
INTERACT WITH THE NEAR EQUATORIAL TROUGH OVER VENEZUELA-COLOMBIA.
THIS IS TO TRIGGER RAINFALL AMOUNTS OF 10-15MM/DAY AND MAXIMA OF
20-35MM. ON SUNDAY IT IS TO THEN INTERACT WITH THE PANAMANIAN LOW
TO ENHANCE CONVECTION ACROSS NORTHWEST COLOMBIA/THE DARIEN IN
EASTERN PANAMA TO FAVOR RAINFALL AMOUNTS OF 15-20MM/DAY AND MAXIMA
OF 30-60MM.

AN EASTERLY WAVE ALONG 81W IS TO ENHANCE ITCZ RELATED CONVECTION
ACROSS PANAMA-COSTA RICA DURING THE NEXT 24-36 HRS...TO FAVOR
RAINFALL AMOUNTS OF 15-20MM/DAY AND MAXIMA OF 30-60MM. OVER EL
SALVADOR/SOUTHERN HONDURAS IT IS TO ALSO TRIGGER RAINFALL AMOUNTS
OF 15-20MM/DAY AND MAXIMA OF 30-60MM ON SATURDAY TO SUNDAY...WHILE
ACROSS CHIAPAS IT WILL SUSTAIN ACCUMULATION OF 25-50MM/DAY AND
MAXIMA OF 75-150MM. OVER GUERRERO OAXACA THIS INCREASES TO
50-75MM/DAY AND MAXIMA OF 125-250MM.

EASTERLY WAVE ALONG 90W AND TO THE SOUTH OF 14N WILL SUSTAIN
ORGANIZED CONVECTION ACROSS SOUTHERN MEXICO...TO TRIGGER RAINFALL
AMOUNTS OF 20-30MM/DAY AND MAXIMA OF 40-80MM. OVER GUERRERO/OAXACA
IT IS TO THEN SUSTAIN RAINFALL AMOUNTS OF 10-15MM/DAY AND MAXIMA
OF 20-45MM ON SATURDAY TO SUNDAY...WITH WAVE TO DISSIPATE LATER ON
SUNDAY.

GAJADHAR...SLMS (SAINT LUCIA)
SUBRATH-ALI...TTMS (TRINIDAD AND TOBAGO)
DAVISON/GALVEZ...WPC (USA)
$$




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