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Prognostic Meteorological Discussion
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FXCA20 KWBC 221846
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TROPICAL DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
246 PM EDT WED MAY 22 2013

DISCUSSION FROM MAY 22/00UTC: SHORT WAVE MID/UPPER TROUGH ACROSS
THE BAHAMAS WILL CONTINUE ENHANCING CONVECTION AND ACCUMULATIONS
ACROSS THE REGION SOUTHWARD INTO EASTERN CUBA/JAMAICA/HISPANIOLA.
THE TROUGH IS FORECAST TO EXIT RAPIDLY WHILE A BROADER TROUGH
REORGANIZES TO THE NORTHWEST. EXITING TROUGH WILL LEAD TO A
GRADUAL DECREASE IN ACCUMULATIONS. THE TROUGH WILL EXTEND ACROSS
THE BAHAMAS INTO HAITI/CENTRAL CARIBBEAN BY 24 HRS...AND TO THE
EAST OF THE BAHAMAS BY 48 HRS. ON DAY 01...EXPECTING HEAVIEST
ACCUMULATIONS OVER THE NORTHERN AND CENTRAL BAHAMAS WITH AMOUNTS
OF 10-15MM/DAY AND MAXIMA OF 20-35MM. OVER SOUTHEASTERN CUBA AND
JAMAICA...EXPECTING 05-10MM/DAY AND MAXIMA OF 15-30MM. EXPECTING
HIGHER AMOUNTS OVER HISPANIOLA IN INTERACTION WITH EASTERLY WAVE
AND DEEP MOIST AIRMASS IN PLACE. EXPECTING ACCUMULATIONS OF
15-30MM/DAY AND MAXIMA OF 40-80MM. BY 36-60 HRS...EXPECTING
HEAVIEST AMOUNTS OVER HISPANIOLA WITH ACCUMULATIONS OF 15-20MM/DAY
AND MAXIMA OF 25-50MM. OVER JAMAICA...EXPECTING 10-15MM/DAY AND
MAXIMA OF 20-35MM. OVER THE BAHAMAS EXPECTING A SHARP DECREASE
WITH STILL THE POSSIBILITY FOR ISOLATED HEAVY THUNDERSTORMS AND
MAXIMA OF 20-35.

DEEP POOL OF PWAT IN THE CARIBBEAN WILL CONTINUE SUSTAINING ACTIVE
CONVECTION ACROSS THE CENTRAL LESSER ANTILLES INTO PUERTO RICO.
THESE ARE INTERACTING WITH UPPER TROUGH OVER THE CENTRAL
CARIBBEAN. OVER PUERTO RICO...EXPECTING MOST ACTIVE TODAY WITH
ACCUMULATIONS OF 15-20MM/DAY AND MAXIMA OF 25-50MM. A SURGE IN
CONVECTION IS EXPECTED ON DAY 03 ASSOCIATED WITH AN INCREASE IN
PWAT AND LOW-LEVEL CONVERGENCE. MODELS DISAGREE IN AMOUNTS WITH
THIS NEW SURGE IN CONVECTION. SO FAR EXPECTING ACCUMULATIONS OF
10-15MM/DAY WITH MAXIMA OF 20-40MM. ACROSS THE LESSER
ANTILLES...ENHANCED TRADE WIND CONVERGENCE AND PRECIPITABLE WATER
WILL SUSTAIN ACTIVE PATTERN OF CONVECTION WITH ACCUMULATIONS OF
05-10MM/DAY AND MAXIMA OF 15-20MM...WITH A SLIGHT INCREASE TOWARDS
LATE CYCLE.

ACROSS MEXICO...MID-UPPER RIDGE IS TO MEANDER OVER
CENTRAL/SOUTHERN MEXICO THROUGH THE CYCLE. THIS WILL LIMIT THE
INTENSITY COVERAGE OF DIURNAL CONVECTION. STILL...DIURNAL
THUNDERSTORMS ARE EXPECTED ACROSS THE EJE VOLCANICO AND ESPECIALLY
THE SIERRA MADRE ORIENTAL WITH ISOLATED ACCUMULATIONS OF
05-10MM/DAY AND ISOLATED MAXIMA OF 15MM. ACROSS NORTHERN CENTRAL
AMERICA...DIURNAL CONVECTION IS FINALLY BECOMING MORE ACTIVE.
MODELS CONTINUE SHOWING CONVECTIVE INSTABILITY BEING SUFFICIENTLY
LARGE TO SUSTAIN MODERATE TO A FEW STRONG DIURNAL THUNDERSTORMS.
IN ADDITION...SUBSIDENCE CAP WILL REMAIN WEAK. EXPECTING HEAVIEST
ACROSS GUATEMALA TO PRODUCE ACCUMULATIONS OF 15-20MM/DAY AND
MAXIMA OF 30-60MM. OVER NORTHERN EL SALVADOR/HONDURAS/NORTHWESTERN
NICARAGUA EXPECTING 10-15MM/DAY AND MAXIMA OF 20-35MM. ON DAYS
02-03 EXPECTING ACCUMULATIONS TO DECREASE TO 10-15MM/DAY AND
ISOLATED MAXIMA OF 20-40MM/DAY IN DIURNAL CONVECTION. ISOLATED
HIGHER AMOUNTS ARE ALWAYS POSSIBLE IN INTERACTION WITH OROGRAPHY.

ACTIVE CONVECTION WILL PERSIST OVER SOUTHERN CENTRAL AMERICA IN
ASSOCIATION WITH DEEP AND LARGE MOISTURE POOL ACROSS SOUTHERN
CARIBBEAN/EASTERN PACIFIC AND AN ITCZ TO THE NORTH OF ITS
CLIMATOLOGICAL POSITION. THIS WILL SUSTAIN NUMEROUS SHOWERS AND
THUNDERSTORMS ACROSS COSTA RICA AND PANAMA THROUGH THE CYCLE.
EXPECTING AMOUNTS OF 15-20MM/DAY AND MAXIMA OF 30-60MM/DAY THROUGH
60 HRS AND A SLIGHT DECREASE ON DAY 02. AS BEST MOISTURE POOL
MOVES WESTWARD...EXPECTING AN INCREASE OVER COSTA RICA/PACIFIC
COAST OF NICARAGUA/GULF OF FONSECA TO PRODUCE ACCUMULATIONS OF
15-20MM/DAY AND MAXIMA OF 35-70MM.

OVER NORTHERN SOUTH AMERICA...ACTIVE CONVECTION WILL PERSIST
ACROSS NORTHERN COLOMBIA/NORTHWESTERN VENEZUELA EARLY IN THE
CYCLE...IN ASSOCIATION WITH AN EASTERLY WAVE AND DEEP MOISTURE
POOL. AMOUNTS WILL START DECREASING TOWARDS MID/LATE CYCLE AS
DRIER AIR MASS MOVES INTO THE REGION. IN TERMS OF
ACCUMULATIONS...EXPECTING HEAVIEST THROUGH 36 HRS ACROSS NORTHERN
COLOMBIA/NORTHWESTERN VENEZUELA WITH AMOUNTS OF 15-30MM/DAY AND
MAXIMA OF 35-70MM WITH A DECREASING TREND AFTERWARDS.

FURTHER EAST...SUBSIDENCE INVERSION ASSOCIATED WITH MID-LEVEL
RIDGE WILL ESTABLISH A TRANSIENT QUIET PATTERN ACROSS NORTHEASTERN
VENEZUELA INTO THE NORTHERN GUIANAS. DRY AND STABLE AIRMASS WILL
GRADUALLY MAKE IT WESTWARD LEADING TO A DECREASE IN ACCUMULATIONS
OVER VENEZUELA THROUGH THE CYCLE. AN ARRIVING TROPICAL WAVE AND
ASSOCIATED MOISTURE SURGE WILL PRODUCE AN INCREASE OVER THE
GUIANAS BY LATE CYCLE. EXPECTING AMOUNTS INCREASING TO 05-10MM/DAY
AND MAXIMA OF 15-20MM.

TROPICAL/EASTERLY WAVES INITIALIZED AT 12UTC

INITIAL 24   36   48   60   72   84   TYPE
40W     43W  46W  49W  52W  55W  58W   TW
74W     76W  79W  82W  85W  87W  89W   EW

TROPICAL WAVE ALONG 40W IS TO ENTER FRENCH GUIANA LATE ON DAY
02...WHERE IT IS TO FAVOR RAINFALL AMOUNTS OF 05-10MM/DAY AND
MAXIMA OF 15-20MM/DAY.

AN EASTERLY WAVE ALONG 74W 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 30-60MM/DAY...INCREASING TO MAXIMA OF
35-70MM/DAY ONCE IT GETS OVER COSTA RICA. LOCALLY HEAVY AMOUNTS
ARE ALSO EXPECTED IN NICARAGUA. WAVE WILL INTERACT WITH REGION OF
ENHANCED TRADE WIND MOISTURE CONVERGENCE AND ENHANCE ACCUMULATIONS
ACROSS JAMAICA AS WELL.

BLENMAN...BMS (BARBADOS)
MCKENZIE...BDM (BAHAMAS)
DAVISON/GALVEZ...WPC (USA)
$$
National Weather Service Weather Forecast Office
