Prognostic Meteorological Discussion
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FXCA20 KWBC 281825
PMDCA

TROPICAL DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
224 PM EDT THU APR 28 2016

TROPICAL DISCUSSION FROM APRIL 28/12UTC: MID/UPPER LEVEL RIDGE
REMAINS WELL ENTRENCHED ACROSS WESTERN PORTIONS OF THE
DOMAIN...ENVELOPING CENTRAL/ SOUTHERN MEXICO-THE GULF AND CENTRAL
AMERICA. THE MID LEVEL AXIS ANCHORS ON A MEANDERING HIGH TO THE
SOUTH-SOUTHWEST OF GUERRERO MEXICO...WHERE IT IS TO REMAIN OVER
THE NEXT FEW DAYS. THROUGH FRIDAY MORNING THE RIDGE TENDS TO BUILD
NORTH ACROSS THE GULF INTO THE CENTRAL USA AS A HIGH AMPLITUDE
TROUGH PROPAGATES ACROSS THE WESTERN USA. BUT IT IS TO THEN
FLATTEN ON SATURDAY AS THE TROUGH RELOCATES TO THE CENTRAL USA.
THE RIDGE ALOFT IS TO INHIBIT DEEP CONVECTIVE DEVELOPMENT ACROSS
MOST OF MEXICO. OVER CENTRAL AMERICA IT WILL BE STRONG ENOUGH TO
DELAY...BUT NOT SUPPRESS...THE ONSET OF AFTERNOON CONVECTION.
ACTIVITY WILL BUILD BETWEEN SOUTHERN CHIAPAS AND WESTERN
NICARAGUA...WITH RAINFALL AMOUNTS OF 05-10MM/DAY AND MAXIMA OF 15.
LOCALLY HIGHER AMOUNTS ARE TO DEVELOP BETWEEN SOUTHEAST
HONDURAS-NORTHWEST NICARAGUA AS LATE EVENING CONVECTION CLUSTERS
ACROSS THE GULF OF FONSECA. IN THIS AREA EXPECTING RAINFALL
AMOUNTS OF 10-15MM/DAY AND MAXIMA OF 20-40MM. THROUGH SATURDAY
AFTERNOON...HOWEVER...THE DAILY MAXIMA WILL DECREASE TO 20-30MM AS
THE TRADE WINDS CAP STRENGTHENS.

UNDER THE STEERING INFLUENCE OF THE RIDGE TO THE WEST...SHORT WAVE
TROUGHS ARE FORECAST TO STREAM ACROSS THE BAHAMAS INTO THE
NORTHERN CARIBBEAN ISLES. ONE MOVES ACROSS HISPANIOLA TO PUERTO
RICO TODAY...WHILE A DEEPER ONE OVER THE SOUTHEAST USA EJECTS
ACROSS THE BAHAMAS TO HISPANIOLA LATER ON FRIDAY. IT REACHES
PUERTO RICO EARLY ON SATURDAY. THE INFLOW OF SHORT WAVE ENERGY
WILL THEN SUSTAIN THE GRADUAL AMPLIFICATION OF A TROUGH ACROSS THE
BAHAMAS-CUBA-HISPANIOLA DURING THE DAY ON SATURDAY. A SUBTROPICAL
JET IS TO GRADUALLY REPOSITION OVER THE NORTHERN CARIBBEAN AS IT
ROUNDS THE BASE OF THE TROUGH. THE TROUGH AND SUBTROPICAL JET
MAXIMA ARE TO SUSTAIN AN UPPER DIVERGENT PATTERN ACROSS
HISPANIOLA-PUERTO RICO-VIRGIN ISLES AND THE NORTHERN LEEWARD
ISLANDS.

AT LOW LEVELS...UNDER INFLUENCE OF THE BROAD MID/UPPER TROUGH OVER
THE WESTERN ATLANTIC...AN INDUCED/INVERTED TROUGH IS TO EXTEND
NORTH ALONG 75W/77W. A RIDGE LIES OVER THE TROPICAL ATLANTIC TO
THE EAST OF THE LESSER ANTILLES...WITH THE MSG DUST PRODUCT
SHOWING A SAHARAN AIR LAYER (SAL)/DUST PROPAGATING ACROSS THE
TROPICAL ATLANTIC TO JUST EAST OF THE LESSER ANTILLES EARLY THIS
MORNING. THE SAL IS TO REMAIN MOSTLY TO THE EAST OF THE
ISLANDS...WHILE THE TROUGH/RIDGE FAVORS A MOIST ADVECTIVE PATTERN
ACROSS THE CENTRAL CARIBBEAN INTO PUERTO RICO-DOMINICAN REPUBLIC.
IN THIS AREA THE PWAT CONTENT IS TO PEAK AROUND 50MM OVER THE NEXT
FEW DAYS. ALSO...AT 700 HPA...A WEST-SOUTHWESTERLY FLOW IS
EXPECTED THROUGH SATURDAY EVENING...ADDING SHEAR TO THE MIX. THIS
COMBINES WITH INFLOW OF MID LEVEL VORTICES AND FAVORABLE JET
DYNAMICS TO SUSTAIN ENVIRONMENTAL CONDITIONS THAT ARE TO REMAIN
HIGHLY FAVORABLE AND CONDUCIVE TO ORGANIZED DEEP CONVECTION.
ACROSS PUERTO RICO AND HISPANIOLA EXPECTING RAINFALL AMOUNTS OF
15-20MM/DAY AND MAXIMA OF 35-70MM/DAY THROUGH SATURDAY MORNING. ON
SATURDAY TO SUNDAY THIS WILL INCREASE TO 25-50MM/DAY AND MAXIMA OF
75-125MM.

SOUTH OVER THE DOMAIN...THE EASTERN PACIFIC ITCZ LIES NORTH OF ITS
CLIMATOLOGICAL POSITION ALONG 08N/09N INTO SOUTHERN CENTRAL
AMERICA/NORTHERN SOUTH AMERICA. THIS IS ENHANCING LOW LEVEL
MOISTURE CONVERGENCE ACROSS PANAMA AND COSTA RICA...WHERE WE
EXPECT RAINFALL AMOUNTS OF 05-10MM/DAY AND MAXIMA OF 15-25MM. MOST
ACTIVE IS TO CLUSTER ALONG THE CONTINENTAL DIVIDE. OVER NORTHWEST
COLOMBIA TO NORTHWEST VENEZUELA EXPECTING RAINFALL AMOUNTS OF
10-15MM/DAY AND MAXIMA OF 20-35MM THROUGH FRIDAY MORNING...AND
MAXIMA OF 20-40MM THEREAFTER. ON THE CAUCA/CAUCA VALLEY TO THE
SOUTHWEST EXPECTING RAINFALL AMOUNTS OF 05-10MM/DAY AND MAXIMA OF
15-20MM. OVER NORTHERN VENEZUELA ITCZ/NET RELATED CONVECTION WILL
SUSTAIN RAINFALL AMOUNTS OF 10-15MM/DAY AND MAXIMA OF 20-40MM.
THROUGH SATURDAY THIS WILL INCREASE TO 25-50MM/DAY AND MAXIMA OF
75-100MM CLUSTERING TO THE NORTHWEST. ACTIVITY IS TO ALSO SPREAD
NORTH INTO THE ABC ISLES ON FRIDAY...WITH ACCUMULATION OF
05-10MM/DAY AND MAXIMA OF 15MM...INCREASING TO 10-15MM/DAY AND
MAXIMA OF 20-40MM ON SATURDAY. OVER SOUTHERN COLOMBIA-AMAZONAS IN
VENEZUELA...A SOUTHERN HEMISPHERE PREFRONTAL SHEAR LINE WILL FAVOR
RAINFALL AMOUNTS OF 25-50MM/DAY AND MAXIMA OF 75-150MM THROUGH
FRIDAY MORNING. ON FRIDAY TO SATURDAY THE FOCUS OF THE HEAVY
CONVECTION SHIFTS NORTH TO PIEDEMONTE LLANERO IN COLOMBIA-CENTRAL
VENEZUELA/RORAIMA HIGHLANDS...WITH RAINFALL AMOUNTS OF 25-50MM/DAY
AND MAXIMA OF 75-125MM. ON SATURDAY TO SUNDAY THIS DECREASES TO
10-15MM/DAY AND MAXIMA OF 20-45MM.

TROPICAL/EASTERLY WAVES INITIALIZED AT 12UTC.
INITIAL    24    36    48    60    72    84    96         TYPE
NONE

CARDOS...SMN (MEXICO)
CABANERIT...INAMEH (VENEZUELA)
DAVISON/GALVEZ...WPC (USA)
$$




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