Prognostic Meteorological Discussion
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FXCA20 KWBC 271515
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TROPICAL DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1114 AM EDT FRI MAY 27 2016

TROPICAL DISCUSSION FROM MAY 27/12UTC: WEST OVER THE DOMAIN...AT
500 HPA...TROUGH OVER THE WESTERN/CENTRAL USA CONTINUES TO PRESS
AGAINST A RIDGE TO THE SOUTH. UNDER PRESSURE...THE RIDGE IS LOSING
ITS FOOTHOLD OVER MEXICO-CENTRAL AMERICA. AS THE RIDGE WEAKENS
CONDITIONS ARE BECOMING MORE FAVORABLE AND CONDUCIVE FOR
CONVECTION TO DEVELOP. THIS IS PARTICULARLY TRUE ALONG THE SIERRA
MADRE ORIENTAL BETWEEN CENTRAL MEXICO AND TAMAULIPAS...WHERE WE
EXPECT RAINFALL AMOUNTS OF 05-10MM/DAY AND MAXIMA OF 20-30MM/DAY
THROUGH EARLY SUNDAY. OTHER CONVECTION IS TO CLUSTER ALONG THE
CONTINENTAL DIVIDE BETWEEN SOUTHERN CHIAPAS AND NORTHWEST
NICARAGUA. IN THIS AREA EXPECTING RAINFALL AMOUNTS OF 10-15MM/DAY
AND MAXIMA OF 20-30MM...WITH LOCALLY HIGHER AMOUNTS EXPECTED ON
THE GULF OF FONSECA REGION BETWEEN HONDURAS-EL SALVADOR AND
NICARAGUA. IN THIS AREA ENVIRONMENTAL CONDITIONS WILL FAVOR
GENERATION OF MESO SCALE CONVECTIVE SYSTEMS THAT ARE TO TRIGGER
RAINFALL AMOUNTS OF 15-20MM/DAY AND MAXIMA OF 30-60MM.

DEEP TUTT LOW OVER THE BAHAMAS EXTENDS A TROUGH ACROSS THE CENTRAL
CARIBBEAN TO PANAMA/NORTHERN COLOMBIA. HIGHLY AMPLIFIED PATTERN IS
FORECAST TO PERSIST OVER THE NEXT COUPLE OF DAYS...WITH BASE OF
THE TROUGH FORECAST TO SLOWLY PULL DURING THE DAY ON SUNDAY. THE
DEEP MID/UPPER LEVEL TROUGH SUSTAINS AN INDUCED/INVERTED TROUGH IN
THE LOW LEVEL TRADES ACROSS THE CENTRAL CARIBBEAN. THE LOW LEVEL
TROUGH IS TO FAVOR A MOIST ADVECTIVE PATTERN THAT IS TO ENHANCE
CONVERGENCE ACROSS HISPANIOLA-JAMAICA TO EASTERN PORTIONS OF CUBA.
IN THIS AREA EXPECTING RAINFALL AMOUNTS OF 10-15MM/DAY AND MAXIMA
OF 20-40MM IN SCATTERED DEEP CONVECTION. OVER THE
CENTRAL-NORTHWEST BAHAMAS...THE TROUGH ALOFT WILL ENHANCE DIURNAL
CONVECTION TO SUSTAIN RAINFALL AMOUNTS OF 05-10MM/DAY AND MAXIMA
OF 15-20MM. FARTHER SOUTH...THE TROUGH IS TO ALSO INTERACT WITH
THE EASTERN PACIFIC ITCZ TO FAVOR ORGANIZED CONVECTION WITH
RAINFALL AMOUNTS OF 15-20MM/DAY AND MAXIMA OF 35-70MM ACROSS COSTA
RICA-PANAMA-NORTHERN COLOMBIA. THROUGH SUNDAY THIS WILL DECREASE
TO 15-20MM/DAY AND MAXIMA OF 25-50MM. ACROSS VENEZUELA...NEAR
EQUATORIAL TROUGH CONVERGENCE WILL FAVOR RAINFALL AMOUNTS OF
10-15MM/DAY AND MAXIMA OF 20-40MM/DAY. LOCALLY HEAVIER AMOUNTS ARE
EXPECTED THROUGH SATURDAY MORNING WHEN MAXIMA IS TO REACH
25-50MM/DAY ESPECIALLY IN SOUTHERN SLOPES OF CENTRAL VENEZUELA.

THE CARIBBEAN TROUGH IS TO ALSO PRESS AGAINST A MID LEVEL RIDGE
OVER THE EASTERN CARIBBEAN. UNDER PRESSURE FROM THIS TROUGH THE
RIDGE IS TO COLLAPSE LATER TODAY. LOW LEVEL WINDS ARE TO THEN VEER
TO THE SOUTHEAST UNDER INFLUENCE OF INDUCED/INVERTED TROUGH OVER
THE CENTRAL CARIBBEAN AND A BUILDING RIDGE TO THE EAST OF THE
ISLAND CHAIN. THE LONG FETCH SOUTHEASTERLY FLOW WILL ADVECT DEEP
TROPICAL MOISTURE ACROSS THE ISLAND CHAIN TO PUERTO RICO/VIRGIN
ISLES STARTING EARLY ON SATURDAY. THIS PATTERN IS TO THEN HOLD
THROUGH THE MEDIUM RANGE PERIOD. ALTHOUGH GLOBAL MODELS AGREE ON
THE MOIST ADVECTIVE PATTERN THEY DIVERGE ON WHAT IMPACT IT IS
GOING TO HAVE ACROSS THE FORECAST AREA...WITH THE EUROPEAN MODELS
DOWNPLAYING POTENTIAL FOR ORGANIZED CONVECTION. TAKING INTO
ACCOUNT TOPOGRAPHICAL FORCING AND IMPROVING MJO ENVIRONMENTAL
CONDITIONS WE ARE LEANING TOWARDS A WETTER SOLUTION. AS A
RESULT...OVER THE LESSER ANTILLES WE FORECAST RAINFALL AMOUNTS OF
05-10MM/DAY AND MAXIMA OF 15-20MM BY SATURDAY-SUNDAY. ON ACROSS
PUERTO RICO/VIRGIN ISLANDS HIGHER AMOUNTS ARE EXPECTED...WITH
ACCUMULATION OF 10-15MM/DAY AND MAXIMA OF 20-35MM.

TROPICAL/EASTERLY WAVES INITIALIZED AT 12UTC.
INITIAL    24    36    48    60    72    84    96         TYPE
44W        46W   48W   50W   52W   54W   56W   58W        EW
72W        75W   78W   DISSIPATES                         TW

A WEAK WAVE IN THE EASTERLY TRADES IS INITIALIZED ALONG 44W. THE
PERTURBATION IS FORECAST TO ENTER FRENCH GUIANA ON SATURDAY
EVENING...TO FAVOR LIGHT TO MODERATE CONVECTION WITH ACCUMULATION
OF 05-10MM/DAY AND MAXIMA OF 15-20MM. ON SUNDAY IT WILL PULL
ACROSS SURINAME WHERE IT IS TO THEN TRIGGER RAINFALL AMOUNTS OF
05-10MM/DAY AND MAXIMA OF 15-20MM.

AN ILL ORGANIZED TROPICAL WAVE EXTENDS ALONG 72W. THIS IS
INTERACTING WITH THE CARIBBEAN TUTT AND THE INDUCED TROUGH IN THE
LOW LEVEL EASTERLY TRADES. AS A RESULT...THE WAVE IS FORECAST TO
DISSIPATE DURING THE DAY ON SATURDAY. MEANWHILE...ACROSS WESTERN
COLOMBIA TO PANAMA THIS WILL RESULT IN RAINFALL AMOUNTS OF
15-20MM/DAY AND MAXIMA OF 35-70MM.

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

$$




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