FXCA20 KWBC 241818
PMDCA

TROPICAL DISCUSSION - INTERNATIONAL DESKS
NWS HYDROMETEOROLOGICAL PREDICTION CENTER CAMP SPRINGS MD
217 PM EDT TUE APR 24 2012

NOTE: THERE IS A RISK OF HEAVY RAINFALL TO AFFECT DOMINICAN
REPUBLIC AND HAITI DURING THE NEXT THREE DAYS...WITH STRONGEST
CONVECTION TO AFFECT NORTHERN SECTIONS OF THE ISLAND DURING TODAY
AND TOMORROW. THIS IS A POTENTIALLY DANGEROUS SITUATION WITH A
RISK FOR FLASH FLOODS AND MUDSLIDES REMAINING THROUGH THURSDAY.

DISCUSSION FROM APR 24/00 UTC: A MID/UPPER RIDGE EXTENDS OVER THE
EASTERN PACIFIC TO THE NORTHEAST INTO CHIHUAHUA/NEW MEXICO. TO THE
NORTHWEST...A MID-UPPER SHORT WAVE TROUGH EXTENDS OFF THE WEST
COAST OF THE UNITED STATES. THE TROUGH IS TO APPROACH BY 48 HRS
AND SUSTAIN LIGHT PRECIPITATION OVER NORTHWESTERN BAJA CALIFORNIA.
EXPECT ACCUMULATIONS OF 05-10MM/DAY AND MAXIMA OF 15MM/DAY. EXPECT
HEAVIEST ALONG THE PACIFIC COAST/WESTERN SLOPES.

TO THE NORTHEAST...A DEEP MID/UPPER TROUGH EXTENDS OVER THE
EASTERN COAST OF THE UNITED STATES. THE TROUGH SUPPORTS TWO
SURFACE FRONTS. ONE EXTENDS ACROSS THE TURKS AND CAICOS-EXTREME
SOUTHEASTERN CUBA-NORTH OF JAMAICA. THE OTHER EXTENDS ALONG THE
NORTHERN BAHAMAS-NORTHERN CUBA-NORTHERN YUCATAN WHILE PROGRESSING
SOUTHEASTWARD. WHILE NORTHERLY WINDS PERSIST...EXPECT SHALLOW
POST-FRONTAL MARINE CONVECTION AND OROGRAPHIC LIFT TO PRODUCE
LIGHT ACCUMULATIONS OVER NORTHERN HONDURAS...WHERE 05-10MM/DAY
WITH MAXIMA OF 15MM/DAY ARE EXPECTED THROUGH THE CYCLE. FURTHER
SOUTH OVER NORTHERN COSTA RICA/NICARAGUA...FAIR WEATHER IS TO
CONTINUE AS BOUNDARY-LAYER REMAINS DRY WITH A FEW SHOWERS
ESPECIALLY ALONG ATLANTIC COAST. EXPECT MOISTURE RETURN BY 72-84
HRS TO PRODUCE LARGER ACCUMULATIONS OVER THE ATLANTIC COAST.
EXPECT 05-10MM/DAY WITH MAXIMA OF 15-25MM/DAY. A DRY PATTERN IS TO
EXTEND ALSO INTO THE WESTERN TWO THIRDS OF CUBA AND THE NORTHERN
AND CENTRAL BAHAMAS...WHERE DRY AIR ADVECTION IS TO CONTINUE
THROUGH THE CYCLE WHILE GRADUALLY WEAKENING.

TO THE EAST OVER JAMAICA-HISPANIOLA AND THE TURKS AND CAICOS...AN
ACTIVE PATTERN WILL PERSIST THROUGH THE CYCLE. MOST OF THE
ACTIVITY IS TO CONCENTRATE NEAR PRE-FRONTAL CONFLUENCE ZONE AND
SHEAR LINE. ALTHOUGH THIS REGION HAS PROGRESSED INTO EASTERN
HISPANIOLA...IT IS FORECAST TO RETROGRESS SLOWLY LEAVING REGION OF
STRONGEST LOW-LEVEL CONVERGENCE OVER THE ISLAND THROUGH 48 HRS. A
SECONDARY SHEAR-LINE IS TO DEVELOP OVER PUERTO RICO BY 48 HRS
PROVIDING TRANSIENT SYNOPTIC FORCING AT LOW-LEVELS...TO THEN
DISSIPATE. A STRENGHTENING OF THE EASTERLIES IS TO PUSH LOW-LEVEL
TROUGH WESTWARD AFTER 60 HRS PRODUCING AN INCREASE IN
PRECIPITATION OVER JAMAICA AND EASTERN CUBA. THE CONCERN OVER
HISPANIOLA REMAINS HIGH. BOUNDARY-LAYER MOISTURE IS TO REMAIN HIGH
THROUGH THE NEXT THREE DAYS WITH PWAT IN EXCESS OF 50MM.
SOUTH/SOUTHEASTERLY WINDS ARE TO ENHANCE LOW-LEVEL CONVERGENCE IN
THE NORTHERN SECTIONS OF THE ISLAND...WHILE NORTHERLY WINDS REACH
THE NORTHERN COAST. THE CONVERGENCE WILL BE ENHANCED BY DIURNAL
CYCLE OF BREEZES AND OROGRAPHY. MID/UPPER DYNAMICS ARE ALSO TO
BECOME MORE FAVORABLE UNDER DIVERGENT PATTERN IN THE RIGHT
ENTRANCE OF AN UPPER-LEVEL JET MAXIMA. OVER SOUTHERN
HISPANIOLA...EXPECT ACCUMULATIONS OF 15-20MM/DAY WITH MAXIMA OF
30-60MM/DAY THROUGH 36 HRS. OVER NORTHERN HISPANIOLA...EXPECT
HEAVIER PRECIPITATION WITH ACCUMULATIONS OF 25-50MM/DAY WITH
MAXIMA OF 75-150MM/DAY THROUGH 36 HRS. NOTE THAT HIGH RESOLUTION
VERSIONS OF THE WRF MODEL ARE SHOWING LOCALIZED MAXIMA IN EXCESS
OF 200MM/DAY. BY 36-60 HRS...AMOUNTS ARE TO DECREASE TO
10-15MM/DAY WITH MAXIMA OF 20-30MM/DAY OVER SOUTHERN PORTIONS OF
THE ISLAND. OVER THE NORTHERN TIER EXPECT 15-20MM/DAY WITH MAXIMA
OF 25-50MM/DAY BY 36-60 HRS. BY 60-84 HRS...EXPECT FURTHER
DECREASE WITH 10-15MM/DAY AND MAXIMA OF 20-30MM/DAY OVER CENTRAL
AND NORTHERN PORTIONS OF THE ISLAND. THIS IS A POTENTIALLY
DANGEROUS SITUATION AND SHOULD BE CLOSELY MONITORED AS THE RISK
FOR LOCAL FLOODING AND MUDSLIDES IS HIGH. OVER EXTREME
SOUTHEASTERN CUBA...EXPECT ACCUMULATIONS OF 05-10MM/DAY WITH
MAXIMA OF 15MM/DAY THROUGH 60 HRS. THESE ARE TO INCREASE TO
10-15MM/DAY AND MAXIMA OF 20-30MM/DAY BY 60-84 HRS AS SHEAR LINE
PROGRESSES WESTWARD AHEAD OF STRENGTHENING EASTERLIES. OVER
JAMAICA EXPECT 05-10MM/DAY WITH MAXIMA OF 15-20MM/DAY THROUGH 36
HRS...INCREASING TO 10-15MM/DAY WITH MAXIMA OF 20-30MM/DAY BY
60-84 HRS.

TO THE EAST...OVER PUERTO RICO...A SUBSIDENCE INVERSION IS
ESTABLISHING AS MID/UPPER RIDGE OVER NORTHERN VENEZUELA RELOCATES
OVER THE NORTHEASTERN CARIBBEAN THROUGH THE CYCLE. BOUNDARY-LAYER
WINDS ARE TO REMAIN WEAK WHILE GRADUALLY SHIFTING FROM
SOUTH/SOUTHEASTERLIES TO EASTERLIES. ACCORDINGLY...EXPECT DIURNAL
BREEZES TO DOMINATE LOW-LEVEL CIRCULATION PATTERNS. ALTHOUGH
MODELS ARE SHOWING A PERSISTENT SUBSIDENCE INVERSION DURING THE
FOLLOWING DAYS...THEY ARE ALSO SUGGESTING A TRANSIENT EROSION BY
42-60 HRS. THIS WILL COINCIDE WITH THE DEVELOPMENT OF A TRANSIENT
SHEAR LINE ACROSS THE ISLAND. ACCORDINGLY...EXPECT A SURGE IN
CONVECTION TO AFFECT MOSTLY AREAS OVER AND NORTHWEST OF THE
CENTRAL CORDILLERA WEDNESDAY AFTERNOON WITH ACCUMULATIONS OF
10-15MM/DAY AND LOCALIZED MAXIMA OF 20-30MM/DAY. OTHERWISE...LIGHT
AND SHALLOW CONVECTION IS EXPECTED...AS A DRIER PATTERN
ESTABLISHES TOWARDS THE WEEKEND. EAST OVER THE MINOR
ANTILLES...EXPECT GENERALLY FAIR WEATHER DURING THE CYCLE WITH
WIDELY ISOLATED CONVECTION.

OVER EASTERN PANAMA/WESTERN COLOMBIA...EXPECT AN ACTIVE PATTERN TO
CONTINUE THROUGH THE CYCLE AS PRE-FRONTAL TROUGH REMAINS OVER THE
REGION AND TROUGH/LOW SOUTH OF PANAMA REMAIN WELL DEFINED.
PERSISTENT LOW-LEVEL ONSHORE FLOW ACROSS THE CHOCO/WESTERN ANDES
IS TO SUSTAIN ACCUMULATIONS OF 15-20MM/DAY AND MAXIMA OF
25-50MM/DAY THROUGH 36 HRS. AMOUNTS ARE TO INCREASE TO 15-20MM/DAY
WITH MAXIMA OF 35-70MM/DAY BY 60-84 HRS. OVER THE CARIBBEAN COAST
OF COLOMBIA AND NORTHERN ANDES...EXPECT ACTIVE PATTERN TO CONTINUE
WHILE PRE-FRONTAL TROUGH ENHANCES CONVERGENCE.
FURTHERMORE...EXPECT A SURGE IN THE EASTERLY TRADES TO INTENSIFY
THE WESTWARD MEANDERING TROUGH AND ESTABLISH A SURFACE LOW WEST OF
CARTAGENA BY 60-84 HRS. AS THE SURFACE LOW ESTABLISHES...EXPECT
ONSHORE FLOW TO PEAK DURING FRIDAY ENHANCING CONVECTIVE
DEVELOPMENT EVEN MORE. INITIALLY...EXPECT ACCUMULATIONS OF
10-15MM/DAY WITH MAXIMA OF 20-30MM/DAY THROUGH 36 HRS GRADUALLY
INCREASING TO 15-20MM/DAY WITH MAXIMA OF 35-70MM/DAY BY 60-84 HRS.
OVER THE COLOMBIAN LLANOS...EXPECT MOST WIDESPREAD CONVECTION TO
INCREASE LATER IN THE CYCLE TO 10-15MM/DAY WITH MAXIMA OF
20-35MM/DAY BY 60-84 HRS. OVER NORTHERN AND EASTERN
VENEZUELA...EXPECT DRIER PATTERN TO CONTINUE AS DRIER AIR MASS IS
ADVECTED FROM THE EAST AND SUBSIDENCE INVERSION PERSISTS. THIS IS
TO FAVOR GENERALLY FAIR WEATHER WITH ISOLATED CONVECTION DURING
THE CYCLE. OVER THE GUIANAS...HOWEVER...A WETTER PATTERN IS
ESTABLISHING AS WEAK EASTERLY WAVE MOVES IN. EXPECT ACCUMULATIONS
TO GRADUALLY INCREASE TO PEAK BY 36-60 HRS WHEN ACCUMULATIONS OF
15-20MM/DAY WITH LOCALIZED MAXIMA OF 30-60MM/DAY ARE EXPECTED.

MARINERO...DGOA/MARN (EL SALVADOR)
SOLORZANO...SMN (HONDURAS)
DAVISON...HPC (USA)
GALVEZ...HPC (USA)
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