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FXCA20 KWBC 211827
PMDCA

TROPICAL DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
226 PM EDT TUE MAY 21 2013

DISCUSSION FROM MAY 21/00UTC: MODELS INITIALIZE A MID/UPPER LEVELS
RIDGE WITH AXIS EXPANDING ACROSS CENTRAL/SOUTHERN MEXICO TO
NORTHERN CENTRAL AMERICA. AT 250 HPA THIS RIDGE PATTERN IS
FORECAST TO PERSIST NEARLY UNCHANGED OVER THE NEXT FEW DAYS. AT
500 HPA...THE RIDGE TENDS TO ERODE ACROSS CENTRAL AMERICA WHILE
HOLDING ACROSS THE CENTRAL-SOUTHERN STATES OF MEXICO. ACROSS
CENTRAL-SOUTHERN MEXICO THIS IS FORECAST TO CONTINUE INHIBITING
ORGANIZED DEEP CONVECTION...WITH LATE AFTERNOON CONVECTION TO
GENERALLY LIMIT TO CENTRAL PORTIONS OF MEXICO ALONG THE SIERRA
MADRE WHERE WE EXPECT RAINFALL AMOUNTS OF 05-10MM/DAY AND MAXIMA
OF 15MM. OVER NORTHERN CENTRAL AMERICA...AS THE MID LEVEL RIDGE
PATTERN CONTINUES TO ERODE...EXPECTING CONVECTION ALONG THE
CONTINENTAL DIVIDE TO CLUSTER OVER NORTHERN EL SALVADOR/SOUTHERN
GUATEMALA. IN THIS AREA INITIALLY EXPECT RAINFALL AMOUNTS OF
05-10MM/DAY AND MAXIMA OF 15MM/DAY. THROUGH 60 HRS THIS WILL
INCREASE TO 05-10MM/DAY AND MAXIMA OF 15-30MM/DAY...FORECAST TO
THEN PERSIST THROUGH 84-96 HRS.

THE RIDGE ALOFT...AS IT HOLDS ACROSS CENTRAL AMERICA TO THE
EASTERN PACIFIC...IT IS VENTING ITCZ RELATED CONVECTION. AT LOW
LEVELS...THE CONVERGENCE ZONE ALIGNS ALONG 08N/10N TO SOUTHERN
CENTRAL AMERICA INTO NORTHERN COLOMBIA/NORTHWEST VENEZUELA. A LOW
OVER PANAMA ANCHORS THE CONVERGENCE ZONE NORTH OF ITS
CLIMATOLOGICAL POSITION. THROUGH 36-48 HRS THE LOW BECOMES BETTER
ORGANIZED...THEN STARTS TO PULL WEST ACROSS PANAMA TO COSTA RICA.
AS IT RELOCATES...ORGANIZED CONVECTION IS EXPECTED TO SHIFT ALONG
THE ITCZ FROM COLOMBIA TO PANAMA-COSTA RICA/SOUTHERN NICARAGUA.
ACROSS COSTA RICA/SOUTHERN NICARAGUA EXPECTING RAINFALL AMOUNTS OF
05-10MM/DAY AND MAXIMA OF 15-30MM/DAY THROUGH 36-48 HRS...AND
15-20MM/DAY AND MAXIMA OF 25-50MM AT 48-72 HRS. ACROSS
PANAMA...CONVECTION IS TO INTENSIFY THROUGH 48 HRS...WHEN WE
EXPECT RAINFALL AMOUNT OF 15-20MM/DAY AND MAXIMA OF 25-50MM.
ACROSS NORTHERN COLOMBIA TO NORTHWEST VENEZUELA EXPECTING MOST
ACTIVE DURING THE NEXT 36-48 HRS...WITH RAINFALL AMOUNTS OF
15-30MM/DAY AND MAXIMA OF 35-70MM. THIS WILL DECREASE TO
05-10MM/DAY AND MAXIMA OF 15-20MM/DAY BY 72-84 HRS. OVER MARACAIBO
REGION IN NORTHWEST VENEZUELA TO SANTANDERES IN COLOMBIA INITIALLY
EXPECT RAINFALL AMOUNTS OF 05-10MM/DAY AND MAXIMA OF 15-25MM/DAY.
THROUGH 48 HRS THIS IS TO ALSO INCREASE TO 15-20MM/DAY AND MAXIMA
OF 25-50MM/DAY...THEN DECREASE TO 05-10MM/DAY AND MAXIMA OF
15-20MM AT 72-96 HRS.

DOWNSTREAM FROM THE UPPER LEVEL RIDGE...OVER THE BAHAMAS-NORTHERN
CARIBBEAN ISLANDS...THE MODEL GUIDANCE SHOWS LOW AMPLITUDE TROUGH
ENVELOPING THE NORTHERN CARIBBEAN ISLES OVER THE NEXT FEW
DAYS...WHILE AT MID LEVELS UNDER INFLUENCE OF AN INVERTED TROUGH A
DISORGANIZED MEANDERING FLOW IS TO PREVAIL. SUBTROPICAL JET MAXIMA
ARE TO ROUND THE BASE OF THE MEANDERING TROUGH...SUSTAINING
PERIODS OF ENHANCED DIVERGENCE ALOFT ACROSS THE NORTHERN CARIBBEAN
ISLANDS. THE LOW LEVEL FLOW PATTERN...IN-CONTRAST...APPEARS BETTER
ORGANIZED WITH A BROAD CELL OF THE SUBTROPICAL RIDGE TO DOMINATE
THE WESTERN ATLANTIC-CARIBBEAN BASIN. UNDER INFLUENCE OF THIS
RIDGE...A MOIST EAST-SOUTHEAST FLOW IS TO PREVAIL ACROSS THE
FRENCH/LEEWARD ISLANDS INTO PUERTO RICO/HISPANIOLA DURING THE NEXT
FEW DAYS. IN THIS AREA PWAT IS TO PEAK AT 55-60MM BY 30-36
HRS...WITH HIGH VALUES TO THEN PERSIST THROUGH THE END OF THE
WEEK.

MOST ACTIVE ACROSS THE NORTHWEST BAHAMAS IS TO RESULT IN RAINFALL
AMOUNTS OF 10-15MM/DAY AND MAXIMA OF 20-35MM...WHILE OVER THE
CENTRAL TO SOUTHEAST BAHAMAS EXPECT MAXIMA TO PEAK AT 15-20MM ON
DAY 02. OVER CUBA...EXPECTING  RAINFALL AMOUNTS OF 05-10MM/DAY AND
MAXIMA OF 15-20MM/DAY. ACROSS HISPANIOLA EXPECT RAINFALL AMOUNTS
OF 05-10MM/DAY AND MAXIMA OF 15-20MM/DAY THROUGH 24 HRS...AND
15-20MM/DAY AND MAXIMA OF 25-50MM/DAY THEREAFTER. ACROSS PUERTO
RICO TO VIRGIN ISLES EXPECT RAINFALL AMOUNTS OF 05-10MM/DAY AND
MAXIMA OF 15-30MM/DAY THROUGH 36 HRS...AND 15-20MM/DAY AND MAXIMA
OF 25-50MM/DAY AT 36-60 HRS. AS MOISTURE SURGES ACROSS THE
FRENCH/LEEWARD ISLES...EXPECTING ACCUMULATION OF 05-10MM/DAY AND
MAXIMA OF 15MM OVER THE NEXT FEW DAYS.

FARTHER EAST...OVER THE TROPICAL ATLANTIC...THE ITCZ MEANDERS WEST
ALONG 05N INTO THE GUIANAS...WHERE IT IS FORECAST TO REMAIN OVER
THE NEXT FEW DAYS. AS IT PERSISTS...EXPECTING ORGANIZED DEEP
CONVECTION TO SUSTAIN RAINFALL AMOUNTS OF 05-10MM/DAY AND MAXIMA
OF 15-20MM/DAY. THROUGH 48 HRS THIS DECREASES TO 00-05MM/DAY AND
MAXIMA OF 10MM.

TROPICAL/EASTERLY WAVES INITIALIZED AT 12UTC

INITIAL 24   36   48   60   72   84   TYPE
31W     33W  36W  39W  42W  46W  49W   TW
68W     72W  75W  78W  80W  82W  84W   EW

TROPICAL WAVE ALONG 31W IS TO ENTER FRENCH GUIANA BY 72-84
HRS...WHERE IT IS TO FAVOR RAINFALL AMOUNTS OF 05-10MM/DAY AND
MAXIMA OF 15-20MM/DAY.

AN EASTERLY WAVE ALONG 68W IS TO INTERACT WITH THE NEAR EQUATORIAL
TROUGH OVER NORTHWEST VENEZUELA/NORTHERN COLOMBIA TO SUSTAIN
RAINFALL AMOUNTS OF 15-30MM/DAY AND MAXIMA OF 35-70MM/DAY. ACROSS
PANAMA/COSTA RICA IT IS TO THEN SUSTAIN RAINFALL AMOUNTS OF
15-20MM/DAY AND MAXIMA OF 25-50MM/DAY...WHILE OVER EASTERN
NICARAGUA EXPECTING RAINFALL AMOUNTS OF 05-10MM/DAY AND MAXIMA OF
15-20MM. OVER JAMAICA IT IS TO RESULT IN RAINFALL AMOUNTS OF
05-10MM/DAY AND MAXIMA OF 15-20MM/DAY BY 36-60 HRS...TO SPREAD
ACROSS THE CAYMAN ISLES THROUGH 72 HRS.

BLENMAN...BMS (BARBADOS)
MCKENZIE...BDM (BAHAMAS)
DAVISON/GALVEZ...WPC (USA)
$$