Prognostic Meteorological Discussion
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FXCA20 KWBC 271823
PMDCA

TROPICAL DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
223 PM EDT WED MAY 27 2015

DISCUSSION FROM MAY 27/12 UTC: MID LEVEL RIDGE MEANDERS ACROSS
NORTHERN STATES OF MEXICO INTO THE NORTHERN GULF...WHILE ANCHORING
ON A HIGH NEAR 24N 100W. MODELS CONTINUE TO FORECAST THIS PATTERN
TO HOLD ACROSS MEXICO WHILE SHORT WAVE PERTURBATIONS STREAM TO THE
NORTH ACROSS THE SOUTHERN USA. A STRONG PERTURBATION IS TO PULL
ACROSS ARIZONA TO NEW MEXICO THROUGH THURSDAY AFTERNOON...TO THEN
QUICKLY PULL ACROSS TEXAS-NORTHEAST STATES OF MEXICO. THIS IS
LIKELY TO TRIGGER SCATTERED DEEP CONVECTION ACROSS COAHUILA
MEXICO...WHERE WE EXPECT RAINFALL AMOUNTS OF 15-20MM/DAY AND
MAXIMA OF 25-50MM IN POTENTIALLY SEVERE CONVECTION. THROUGH FRIDAY
THE FOCUS OF THE ACTIVITY SHIFTS TO CHIHUAHUA/COAHUILA...WITH
RAINFALL AMOUNTS OF 05-10MM/DAY AND MAXIMA OF 15-20MM. THE MID
LEVEL RIDGE IS TO DELAY...BUT NOT SUPPRESS...DIURNAL CONVECTION ON
THE CENTRAL-SOUTHERN STATES OF MEXICO. IN THIS AREA EXPECTING
RAINFALL AMOUNTS OF 10-15MM/DAY AND MAXIMA OF 20-45MM THROUGH THIS
EVENING. THEREAFTER...EXPECT RAINFALL AMOUNTS OF 05-10MM/DAY AND
MAXIMA OF 20-30MM/DAY. OVER SOUTHERN GUATEMALA MOST EXPECT
SCATTERED DIURNAL CONVECTION TO SUSTAIN RAINFALL AMOUNTS OF
05-10MM/DAY AND MAXIMA OF 15MM.

ALSO AT MID LEVELS...A SHORT WAVE RIDGE IS TO MEANDER OVER THE
WESTERN ATLANTIC/EASTERN USA. DOWNSTREAM FROM THIS AXIS A BROAD
TUTT DOMINATES THE FLOW BETWEEN 70W-50W AND TO THE NORTH OF
15N...WHILE ANCHORING ON A CLOSED LOW NEAR 27N 60W. LATER ON
THURSDAY/EARLY FRIDAY MORNING THE TUTT WILL START TO LIFT WHILE
YIELDING TO A BUILDING CELL OF THE SUBEQUATORIAL RIDGE OVER THE
LESSER ANTILLES/EASTERN CARIBBEAN. AS THE TUTT MEANDERS TO THE
NORTH THIS IS TO ENHANCE DIURNAL CONVECTION ACROSS PUERTO RICO AND
HISPANIOLA... WHERE WE EXPECT RAINFALL AMOUNTS OF 05-10MM/DAY AND
MAXIMA OF 15-30MM. THE TUTT ALOFT ALSO SUSTAINS AN INDUCED TROUGH
IN THE EASTERLY TRADES. AS IT ENTERS THE BASIN THIS IS TO ENHANCE
MOISTURE TRANSPORT/CONVERGENCE AND SUSTAIN AN INCREASE IN
CONVECTION ACROSS THE WESTERN CARIBBEAN ISLES. SEE BELOW FOR
DETAILS.

ALSO...UNDER THE INFLUENCE OF THE MID LEVEL RIDGE TO THE
WEST...THE TUTT BRANCHES TO THE SOUTHWEST TO THE CENTRAL/SOUTHERN
CARIBBEAN. ALONG THIS AXIS CLOSED LOW IS TO FORM TO THE
SOUTH-SOUTHWEST OF JAMAICA EARLY IN THE CYCLE. THROUGH THURSDAY
EVENING THIS LIFTS TO THE NORTHWEST TO THE CAYMAN ISLES/ NORTHWEST
CARIBBEAN...WHERE IT IS TO REMAIN THROUGH FRIDAY EVENING. AS IT
RETROGRESSES ACROSS THE BASIN THIS IS TO THEN PHASE WITH AN UPPER
LEVEL SHORT WAVE TROUGH THAT IS TO MEANDER OVER THE FLORIDA
PENINSULA/WESTERN CUBA. POSITIVE INTERACTION WITH UPPER LEVEL
FEATURE WILL HELP SUSTAIN THE MID LEVEL TROUGH. THE RETROGRESSING
LOW IS TO ENHANCE CONVECTION ACROSS JAMAICA...WITH MOST ACTIVE
EXPECTED ON THURSDAY TO FRIDAY...WITH RAINFALL AMOUNTS OF
10-15MM/DAY AND MAXIMA OF 20-35MM. THE LOW IS TO ALSO ENHANCE
CONVECTION ACROSS THE CAYMAN ISLES AND EASTERN PORTIONS OF
CUBA...WHERE THUNDERSTORMS ARE HIGHLY LIKELY ON THURSDAY. DURING
THAT PERIOD ALSO EXPECTING RAINFALL AMOUNTS OF 10-15MM/DAY AND
MAXIMA OF 20-35MM. LATER IN THE CYCLE...AS THE MID LEVEL LOW
INTERACTS WITH UPPER TROUGH...EXPECTING SCATTERED CONVECTION
ACROSS WESTERN PORTIONS OF CUBA TO SUSTAIN RAINFALL AMOUNTS OF
05-10MM/DAY AND MAXIMA OF 15-25MM.

FURTHERMORE...THE MEANDERING MID LEVEL TROUGH IS TO INDUCED THE
NORTHWARD AMPLIFICATION OF THE PANAMANIAN LOW/TROUGH ACROSS THE
ISTHMUS INTO THE CENTRAL CARIBBEAN ON WEDNESDAY TO THURSDAY. THE
DEEPENING TROUGH IS TO ENHANCE MOIST INFLOW ACROSS THE WESTERN
COASTAL PLAINS OF COLOMBIA INTO THE ANDEAN REGION WHILE ALSO
INDUCING THE NORTHWARD MODULATION OF THE EASTERN PACIFIC ITCZ INTO
NORTHWEST COLOMBIA AND EASTERN PANAMA. ACROSS WESTERN COLOMBIA TO
EASTERN PANAMA EXPECTING RAINFALL AMOUNTS OF 15-20MM/DAY AND
MAXIMA OF 35-70MM. CONVECTION IS TO PEAK ON THURSDAY TO FRIDAY
WHEN WE EXPECT RAINFALL AMOUNTS OF 20-30MM/DAY AND MAXIMA OF
40-80MM/DAY. THIS IS TO ALSO FAVOR A SURGE IN ACTIVITY ACROSS
NORTHWEST VENEZUELA ON THURSDAY THROUGH FRIDAY...WHERE WE EXPECT
RAINFALL AMOUNTS OF 15-20MM/DAY AND MAXIMA OF 25-50MM. OVER
WESTERN PANAMA-COSTA RICA TO SOUTHERN NICARAGUA...
MEANWHILE...EXPECTING RAINFALL AMOUNTS OF 05-10MM/DAY AND MAXIMA
OF 15-20MM IN A DIURNAL PATTERN.

TROPICAL/EASTERLY WAVES INITIALIZED AT 12UTC
INITIAL  24     36     48     60     72     84     96        TYPE
60W      63W    65W    67W    70W    72W    73W    74W    TUTT
INDCD.

THE TUTT INDUCED TROUGH IS TO SLOWLY MOVE WEST ACROSS THE LEEWARD
ISLES DURING THE DAY ON WEDNESDAY...AND ACROSS PUERTO RICO TO THE
DOMINICAN REPUBLIC LATER ON THURSDAY. AS THE LOW LEVEL WINDS VEER
TO THE SOUTHEAST THIS IS TO ENHANCE ITCZ MOISTURE ADVECTION ACROSS
THE ISLAND CHAIN TO THE EASTERN CARIBBEAN. DEEP MOISTURE OVER THE
ISLAND CHAIN IS TO GRADUALLY EBB THROUGH SATURDAY...WHEN A TRADE
WINDS SURGE ENTERS THE ISLAND CHAIN/EASTERN CARIBBEAN.
HOWEVER...HIGH MOISTURE CONTENT VALUES ARE TO PERSIST OVER PUERTO
RICO-HISPANIOLA THROUGH MONDAY. AS THE MOISTURE SURGES ACROSS THE
ISLAND CHAIN EXPECTING SCATTERED CONVECTION ACROSS THE
LEEWARD/VIRGIN ISLES TO SUSTAIN RAINFALL AMOUNTS OF 05-10MM/DAY
AND MAXIMA OF 15-30MM. OVER PUERTO RICO AND HISPANIOLA THIS IS TO
THEN FAVOR RAINFALL AMOUNTS OF 10-15MM/DAY AND MAXIMA OF 20-45MM
IN ORGANIZED CONVECTION ON FRIDAY TO SATURDAY.

OTHER CONVECTION TO THE SOUTH IS EXPECTED AS THE TUTT/INDUCED
TROUGH INTERACT WITH THE ATLANTIC ITCZ...SUSTAINING A MOIST SURGE
ACROSS THE NORTHERN GUIANAS/ORINOCO DELTA REGION IN VENEZUELA
LATER TODAY INTO THE WINDWARD ISLES/EASTERN VENEZUELA EARLY ON
THURSDAY MORNING. ACROSS THE NORTHERN GUIANAS INITIALLY EXPECTING
RAINFALL AMOUNTS OF 05-10MM/DAY AND MAXIMA OF 15-30MM. DAILY
MAXIMA DECREASE TO 15MM THROUGH SATURDAY MORNING. THROUGH THE DAY
ON THURSDAY THE FOCUS OF THE CONVECTION SHIFTS FROM NORTHERN
GUYANA TO NORTHEAST VENEZUELA AND THE SOUTHERN WINDWARD
ISLES...WITH RAINFALL AMOUNTS OF 10-15MM/DAY AND MAXIMA OF
20-40MM. OVER CENTRAL-WESTERN VENEZUELA THIS IS TO THEN FAVOR
RAINFALL AMOUNTS OF 10-15MM/DAY AND MAXIMA OF 20-40MM.

CRAIG...TTMS (TRINIDAD AND TOBAGO)
SAMUEL...MDS (SURINAME)
DAVISON...WPC (USA)
$$




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