TROPICAL DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
242 PM EDT THU MAY 16 2013

NOTE: TROPICAL DESK PRODUCTS WILL BE AVAILABLE AGAIN ON MONDAY MAY
20TH 2013.

DISCUSSION FROM MAY 16/00UTC: A 500 HPA HIGH LIES OVER
SOUTHWESTERN MEXICO-NORTHERN CENTRAL AMERICA INTO THE WESTERN
CARIBBEAN. RIDGE IS FORECAST TO HOLD AND CONTINUE FAVORING A
SUBSIDENCE CAP WHILE INHIBITING ORGANIZED DEEP CONVECTION.
HOWEVER...IT WILL STILL ALLOW WIDELY SCATTERED LATE AFTERNOON
CONVECTION ACROSS HIGHER ELEVATIONS. MOST ACTIVE IS EXPECTED ALONG
THE HIGH ELEVATIONS OF THE SIERRA MADRE ORIENTAL/CENTRAL MEXICO
WITH ACCUMULATIONS OF 05-10MM/DAY AND MAXIMA OF 15MM THROUGH THE
PERIOD. THIS WILL ALSO BE THE CASE IN THE CONTINENTAL DIVIDE
ACROSS GUATEMALA/EL SALVADOR/HONDURAS...WITH A LIGHTER AMOUNTS
EARLIER IN THE CYCLE.

TO THE EAST...A MID/UPPER LEVEL TROUGH DOMINATES THE NORTHEASTERN
CARIBBEAN. THE UPPER CONVERGENT TIER OF THIS TROUGH IS AFFECTING
THE NORTHERN ANTILLES SUSTAINING A SUBSIDENCE CAP AND LEADING TO
GENERALLY LIGHT ACCUMULATIONS IN SHALLOW CONVECTION. MOST ACTIVE
REMAINS TO THE SOUTH OF HISPANIOLA INTO THE NORTHEASTERN
CARIBBEAN...AS A REGION OF LOW-LEVEL TRADE WIND CONVERGENCE HAS
BEEN INTERACTING WITH UPPER TROUGH...ENHANCING SHOWERS AND
THUNDERSTORMS. THIS HAS LEAD TO A MOIST AIRMASS THAT WILL ENHANCE
ACTIVITY ACROSS THE DOMINICAN REPUBLIC...HAITI...JAMAICA AND
SOUTHEASTERN CUBA/SOUTHERN BAHAMAS LATER IN THE CYCLE.
ACROSS JAMAICA...EXPECTING MOST ACTIVE THROUGH 36 HRS WHEN
SCATTERED CONVECTION WILL PRODUCE ACCUMULATIONS OF 10-15MM/DAY AND
MAXIMA OF 20-35MM. AMOUNTS ARE TO DECREASE AFTERWARDS AS DEEPER
MOISTURE/CONVECTIVE INSTABILITY CONCENTRATE FURTHER NORTH ACROSS
CUBA/SOUTHERN BAHAMAS. ACROSS CUBA...EXPECTING AN INCREASING
TREND. EXPECTING INITIAL ACCUMULATIONS OF 05-10MM/DAY AND ISOLATED
MAXIMA OF 15MM/DAY. BY LATE CYCLE EXPECTING DIURNAL CONVECTION
ACROSS THE ENTIRE ISLAND TO PRODUCE ACCUMULATIONS OF 05-10MM/DAY
AND MAXIMA OF 15-20MM IN NORTH-CENTRAL PARTS...AND MAXIMA OF
20-35MM ACROSS THE SOUTHEASTERN TIER. ACROSS THE CENTRAL/SOUTHEAST
BAHAMAS...EXPECTING SHOWERS TO BECOME MORE WIDESPREAD TOWARDS LATE
CYCLE WITH ACCUMULATIONS OF 05-10MM/DAY AND MAXIMA OF 15MM.

FURTHER EAST...CONVERGENT TIER OF UPPER TROUGH WILL START
DECREASING ACCUMULATIONS OVER PUERTO RICO/VI AND THE LEEWARD
ISLANDS TODAY AS SUBSIDENCE CAP STRENGTHENS. STILL...SOME DIURNAL
THUNDERSTORMS WILL PRODUCE LOCAL ACCUMULATIONS OF 05-10MM/DAY AND
MAXIMA OF 15-30MM OVER PUERTO RICO...DECREASING AFTERWARDS. A WEAK
UPPER JET MAXIMA WILL ENHANCE UPPER DIVERGENCE OVER THE NORTHERN
FRENCH ANTILLES/LEEWARDS EARLY IN THE CYCLE. YET...LOW-LEVEL
MOISTURE CONVERGENCE IS DECREASING...SO THE EFFECTS OF THE JET ON
PRECIPITATION WILL BE LIMITED. EXPECTING ACCUMULATIONS OF
05-10MM/DAY WITH ISOLATED MAXIMA OF 15MM. DRIER CONDITIONS ARE TO
PREVAIL FURTHER SOUTH ACROSS THE WINDWARD ISLANDS/BARBADOS UNDER
INFLUENCE OF MID-LEVEL RIDGE. EXPECTING ISOLATED LIGHT RAIN
SHOWERS INCREASING IN COVERAGE/INTENSITY TOWARDS LATE CYCLE.

OVER THE EASTERN PACIFIC...THE PANAMANIAN LOW CONTINUES TO
DOMINATE THE LOW LEVEL CIRCULATION OFF THE COAST OF COLOMBIA. THIS
IS INCREASING CONVECTION ACROSS EXTREME NORTHWESTERN COLOMBIA INTO
PANAMA. LOW WILL HOLD THROUGH MID CYCLE WHILE SLOWLY MOVING
WESTWARD AND WEAKENING. IN THE MEAN TIME...THE GULF OF PANAMA WILL
CONTINUE BEING THE FOCUS FOR THE GENERATION OF MESOSCALE
CONVECTIVE SYSTEMS. THIS WILL LEAD TO AN INCREASE IN ACCUMULATIONS
ACROSS COSTA RICA/WESTERN PANAMA TOWARDS LATE CYCLE...AND A
DECREASE IN WESTERN COLOMBIA. ACROSS PANAMA EXPECTING MODERATE
CONVECTION TO RESULT IN RAINFALL AMOUNTS OF 10-15MM/DAY AND MAXIMA
OF 20-35MM THROUGH 36 HRS...DECREASING GRADUALLY AFTERWARDS.
ACROSS COSTA RICA...EXPECTING AMOUNTS GRADUALLY INCREASING TO
PRODUCE 10-15MM/DAY AND ISOLATED MAXIMA OF 20-35MM BY LATE CYCLE.

ACROSS COLOMBIA...EXPECTING A DECREASING TREND AS PANAMANIAN LOW
MOVES AWAY AND EVENTUALLY DISSIPATES. DIURNAL CONVECTION WILL
STILL BE FAVORED. ANY DIURNAL CONVECTION WILL PRODUCE
ACCUMULATIONS OF 10-15MM/DAY AND ISOLATED MAXIMA OF 20-45MM ACROSS
WESTERN COLOMBIA/EJE CAFETERO THROUGH 36 HRS...GRADUALLY
DECREASING TO 05-10MM/DAY AND MAXIMA OF 15-25MM ON DAY 03. ACTIVE
CONVECTION IS TO PERSIST ACROSS THE EASTERN PLAINS OF COLOMBIA
INTO THE SOUTHERN TIER OF VENEZUELA. EXPECTING ACCUMULATIONS OF
10-15MM/DAY AND MAXIMA OF 20-35MM/DAY. ENHANCEMENT IS EXPECTED IN
COLOMBIA ON DAY 02 ASSOCIATED WITH SOUTHERLY SURGE ARRIVING FROM
PERU/ECUADOR.

TO THE EAST...MOST ACTIVE REMAINS ACROSS THE GUIANAS IN
ASSOCIATION WITH ACTIVE ATLANTIC ITCZ. MID-LEVEL RIDGE TO THE
NORTH WILL SUSTAIN LESS ACTIVE PATTERN ACROSS NORTHERN VENEZUELA
INTO TRINIDAD/TOBAGO AND NORTHERN GUIANA THROUGH 36-48 HRS.
MOISTURE SURGE ALONG ITCZ WILL HOWEVER COMPETE WITH UPPER RIDGE BY
MID-LATE CYCLE LEADING TO AN INCREASE IN ACCUMULATIONS. BY DAY
03...AMOUNTS ARE TO INCREASE IN EASTERN VENEZUELA/NORTHERN
GUIANA/NORTHERN SURINAME TO PRODUCE 10-15MM/DAY AND MAXIMA OF
20-40MM. FURTHER SOUTH ACROSS FRENCH GUIANA/SOUTHERN
SURINAME...EXPECTING A DECREASING TREND WITH HEAVIEST
ACCUMULATIONS TODAY REACHING 10-15MM/DAY AND MAXIMA OF 20-45MM.

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