052
FXCA20 KWBC 071826
PMDCA
TROPICAL DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
225 PM EDT TUE MAY 07 2024
FORECAST BULLETIN 07 MAY 2024 AT 1900 UTC:
THE PRESENCE OF A PERSISTENT ROBUST MID-LEVEL RIDGE IN SOUTHERN
MEXICO WILL CONTINUE TO FAVOR DRY WEATHER CONDITIONS THROUGH THE
FORECAST CYCLE. HOWEVER...THE PERSISTENT RIDGE IS FAVORING THE
PERSISTENCE OF MID/UPPER TROUGH PATTERN ACROSS THE CENTRAL EASTERN
CARIBBEAN. IN AREAS TO THE WEST OF HISPANIOLA...DRY AIR IN THE
MID-TROPOSPHERE WILL LIKELY LIMIT ANY SIGNIFICANT PRECIPITATION
AMOUNTS. HOWEVER...HISPANIOLA...PUERTO RICO AND THE LEEWARD
ISLANDS ARE PRONE TO WETTER CONDITIONS AS THE UPPER DIVERGENT TIER
OF THE UPPER TROUGH INTERACTS WITH A WEAK SURFACE FRONT AND A
MOIST PLUME THAT IS EXCEEDING 50MM IN TERMS OF PRECIPITABLE WATER
AMOUNTS.
REGARDING THE POSITIONS OF THE AFOREMENTIONED FRONT...ON TUESDAY
EXPECT THE BOUNDARY TO CONTINUE EXTENDING ZONALLY ALONG THE
LEEWARD ISLANDS...PUERTO RICO...NORTHERN HISPANIOLA AND SOUTHEAST
CUBA. BY WEDNESDAY EVENING EXPECT A WEAKENING OF THE BOUNDARY IN
AREAS TO THE WEST OF HISPANIOLA WHILE THE FRONT HOLDS IN AREAS TO
THE EAST. BY THURSDAY...EXPECT THE FRONT TO MEANDER NORTHWARD AWAY
FROM THE LEEWARD ISLANDS AND PUERTO RICO WHILE WEAKENING. THROUGH
WEDNESDAY MORNING...EXPECT 15-20MM/DAY AND MAXIMA OF 30-60MM IN
HISPANIOLA...INCLUDING A MARGINAL RISK OF SEVERE CONVECTION. IN
PUERTO RICO AND THE LEEWARD ISLANDS EXPECT GENERALLY MAXIMA OF
20-35MM ALSO WITH A MARGINAL RISK FOR SEVERITY. A SHEAR LINE
STRUCTURE ACROSS THE SOUTHERN LEEWARD ISLANDS WILL FAVOR ISOLATED
MAXIMA OF 15-20MM. ON WEDNESDAY...INTERACTIONS BETWEEN A SHORT
WAVE TROUGH AND THE SURFACE FRONT WILL FAVOR MAXIMA OF 20-45MM IN
THE LEEWARD ISLANDS...WHILE IN PUERTO RICO AND HISPANIOLA EXPECT
MAXIMA OF 20-35MM. NOTE A CONTINUED MARGINAL RISK FOR SEVERE
CONVECTION IN PUERTO RICO AND THE LEEWARD ISLANDS. EXPECT A
NOTICEABLE DECREASE IN THE COVERAGE AND INTENSITY OF CONVECTION ON
THURSDAY.
TO THE SOUTH...THE SUBEQUATORIAL RIDGE CONTINUES TO PROVIDE
VENTILATION FOR DEEP CONVECTION IN NORTHERN SOUTH AMERICA AND
SOUTHERN CENTRAL AMERICA. ADDITIONAL FORCING FOR ASCENT IS
OCCURRING IN THE BASE OF THE MID-LEVEL TROUGH LOCATED IN THE
CENTRAL CARIBBEAN. THIS...IN COMBINATION WITH EASTERLY WAVES
PROPAGATING INTO COLOMBIA WILL FAVOR A SEASONALLY ACTIVE
CONVECTIVE REGIME AND MODERATE TO LOCALLY HEAVY PRECIPITATION
AMOUNTS IN COLOMBIA AND SOUTHERN CENTRAL AMERICA DURING THE
FORECAST CYCLE. MODELS CONTINUE RESOLVING A STREGTHENING OF THE
PANAMANIAN LOW CIRCULATION. THEY DO DIFFER IN RESOLVING THE
PRECISE EVOLUTION...BUT THEY ARE SUGGESTING A WEAK CENTRAL
AMERICAN GYRE (CAG) - LIKE CIRCULATION DEVELOPING NEAR PANAMA
WEDNESDAY...WHICH IS THEN FORECAST TO MEANDER WEST INTO THE
EASTERN PACIFIC BY FRIDAY. THE PRESENCE OF THE PERSISTENT
MID-LEVEL RIDGE OVER MEXICO AND WEST CENTRAL AMERICA WILL LIKELY
LIMIT THE MIGRATION OF HEAVY RAIN PRODUCING CELLS INTO AREAS WEST
AND NORTH OF NICARAGUA...LIMITING THE WETTER POTENTIAL TO COSTA
RICA AND PANAMA. IN TERMS OF ACCUMULATION...THE HEAVIEST
PERCIPITATION THROUGH WEDNESDAY MRONING IS EXPECTED IN WESTERN
COLOMBIA AND THE DARIEN...WHERE EXPECT MAXIMA OF 50-100MM AND A
RISK FOR MCS FORMATION. IN NORTHERN COLOMBIA...AN EASTERLY WAVE
WILL TRIGGER MAXIMA OF 30-60MM. BY WEDNESDAY THROUGH EARLY
THURSDAY EXPECT MAXIMA OF 50-100MM DEVELOPING IN WESTERN
PANAMA...WHILE IN EASTERN PANAMA AND WESTERN COLOMBIA EXPECT
MAXIMA OF 40-80MM. BY THURSDAY...AN APPROACHING EASTERLY WAVE WILL
AID WITH THE ENHANCEMENT OF ONSHORE FLOW INTO THE MAGDALENA MEDIO.
THIS WILL ENHANCE THE RISK FOR NOCTURNAL MCS FORMATION AND
POTENTIAL MAXIMA OF 75-125MM. IN NORTHWEST COLOMBIA...CONTINUED
ONSHORE FLOW WILL FAVOR MAXIMA OF 30-60MM. IN SOUTHERN COSTA RICA
AND MOST OF PANAMA...INTERACTIONS WITH A DISSIPATING EASTERLY WAVE
AND THE ENHANCED PANAMANIAN LOW WILL FAVOR MAXIMA GENERALLY IN THE
20-40MM/DAY RANGE. NOTE THAT THERE IS SIGNIFICANT UNCERTAINTY ON
THE PRECISE EVOLUTION OF THE PANAMANIAN LOW/WEAK CAG IN SOUTHERN
CENTRAL AMERICA BY THURSDAY/FRIDAY...THUS THE LATTER FORECAST IS
PRONE TO ADJUSTMENTS.
OTHER REGIONS WHERE MODERATE PRECIPITATION IS EXPECTED ARE ALONG
THE ITCZ/NET IN NORTHERN SOUTH AMERICA...WHERE PROPAGATING
EASTERLY WAVES WILL ALSO PLAY A ROLE. GIVEN ENHANCEMENT OF UPPER
DIVERGENT ALONG THE SOUTHERN PERIPHERY OF A CELL OF THE
SUBEQUATORIAL RIDGE...EXPECT PERIODS WITH MAXIMA EXCEEDING 2
INCHES/50MM FROM NORTHERN BRAZIL AND FRENCH GUIANA INTO SOUTHERN
VENEZUELA.
GALVEZ/CLARKE/LEDESMA...WPC (USA)
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