Prognostic Meteorological Discussion
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000
FXCA20 KWBC 281813
PMDCA

TROPICAL DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
212 PM EDT THU MAY 28 2015

AT 15 UTC TROPICAL STORM ANDRES CENTERED NEAR 11.6N 111.3W...WITH
MAXIMUM SUSTAINED WINDS OF 35KT AND MINIMUM CENTRAL PRESSURE OF
1002 HPA. THE STORM IS MOVING TO THE WEST-NORTHWEST AT 12KT. SEE
NHC BULLETIN FOR OFFICIAL FORECAST.

DISCUSSION FROM MAY 28/12 UTC: WEST OVER THE DOMAIN...A 500 HPA
RIDGE EXTENDS ACROSS CENTRAL/NORTHERN MEXICO WHILE ANCHORING ON A
CLOSED HIGH TO THE WEST OF COLIMA/NAYARIT. THE RIDGE IS STEERING
TS ANDRES TO THE WEST-NORTHWEST...WITH THE NHC FORECASTING THIS
STORM TO GRADUALLY STRENGTHEN TO A HURRICANE. ALTHOUGH THIS IS TO
INDUCE THE NORTHWARD MODULATION OF THE EASTERN PACIFIC ITCZ...THE
CONVERGENCE ZONE IS FORECAST TO REMAIN FAR OFFSHORE. A SLIGHT
INCREASE IN MOISTURE...HOWEVER...IS POSSIBLE ALONG THE COAST OF
GUERRERO-COLIMA...WHERE WE EXPECT SCATTERED DIURNAL CONVECTION TO
RESULT IN RAINFALL AMOUNTS OF 10-15MM/DAY AND MAXIMA OF 20-30MM.
ACROSS SOUTHERN CHIAPAS-GUATEMALA THE DIURNAL CONVECTION IS TO
ONLY FAVOR RAINFALL AMOUNTS OF 05-10MM/DAY AND MAXIMA OF 15MM
THROUGH FRIDAY...INCREASING TO 05-10MM/DAY AND MAXIMA OF 15-30MM
ON SATURDAY TO SUNDAY.

SHORT WAVE PERTURBATIONS ARE TO STREAM TO THE NORTH OF THIS
RIDGE...WITH ONE TO PULL ACROSS NEW MEXICO TO TEXAS/NORTHERN
COAHUILA MEXICO EARLY IN THE CYCLE. THIS IS TO THEN LIFT ACROSS
TEXAS...MEANWHILE TRIGGERING SCATTERED DEEP CONVECTION WITH
RAINFALL AMOUNTS OF 15-20MM/DAY AND MAXIMA OF 25-50MM IN
POTENTIALLY SEVERE CONVECTION. AS THE TROUGH PULLS AWAY THE FOCUS
OF THE CONVECTION WILL SHIFT ALONG THE NORTHERN PORTIONS OF THE
SIERRA MADRE ORIENTAL...WHERE WE EXPECT RAINFALL AMOUNTS OF
05-10MM/DAY AND MAXIMA OF 15-20MM.

ANOTHER MID/UPPER LEVEL RIDGE LIES ACROSS THE WESTERN
ATLANTIC/EASTERN USA...WHERE IT IS FORECAST TO HOLD OVER THE NEXT
FEW DAYS. DOWNSTREAM FROM THIS RIDGE A BROAD TUTT DOMINATES THE
FLOW NORTH OF THE ISLANDS WHILE CENTERING ON A CLOSED LOW NEAR 26N
62W. LATER ON THURSDAY/EARLY FRIDAY MORNING THE TUTT WILL START TO
LIFT AS A BROAD CELL OF THE SUBEQUATORIAL RIDGE BUILDS ACROSS THE
TROPICAL ATLANTIC TO THE EASTERN CARIBBEAN. BROAD RIDGE IS TO
REACH MAXIMUM AMPLITUDE LATER DURING THE WEEKEND. AS THE TUTT
PULLS AWAY...A TUTT INDUCED PERTURBATION IS TO PULL ACROSS THE
EASTERN TO THE CENTRAL CARIBBEAN. ON ITS WAKE...A MOIST PLUME IS
TO QUICKLY ADVECT ACROSS THE LESSER ANTILLES TO THE EASTERN
CARIBBEAN...WHERE IT IS TO FEED CONVECTIVE DEVELOPMENT OVER THE
NEXT FEW DAYS. SEE BELOW FOR DETAILS.

SATELLITE IMAGERY ALSO SHOWS ANOTHER TUTT LOW NEAR THE CAYMAN
ISLANDS. THIS EXTENDS A SHORT WAVE TROUGH TO THE SOUTHERN
CARIBBEAN/CENTRAL AMERICA. TUTT PATTERN IS FORECAST TO HOLD OVER
THE NEXT FEW DAYS WITH UPPER LEVEL AXIS TO STRETCH FROM SOUTH
FLORIDA...ACROSS WESTERN CUBA TO THE WESTERN/CENTRAL CARIBBEAN. AT
LOW LEVELS...THE TUTT PATTERN ALOFT CONTINUES TO INTERACT WITH THE
PANAMANIAN LOW/TROUGH...SUSTAINING NORTHWARD AMPLIFICATION OF THE
TROUGH INTO THE CENTRAL CARIBBEAN. THIS...IN-TURN...SUSTAINS A
MOIST SURGE ACROSS THE CENTRAL CARIBBEAN. THIS IS TO FEED
CONVECTIVE DEVELOPMENT ACROSS JAMAICA-CUBA AND THE CAYMAN ISLANDS.
MOST ACTIVE IS EXPECTED ON THURSDAY AND SATURDAY...WHEN IT IS TO
FAVOR RAINFALL AMOUNTS OF 15-20MM/DAY AND MAXIMA OF 25-50MM. THE
UPPER TROUGH IS TO ALSO ENHANCE DIURNAL CONVECTION ACROSS WESTERN
PORTIONS OF CUBA...WHERE IT IS TO SUSTAIN RAINFALL AMOUNTS OF
05-10MM/DAY AND MAXIMA OF 15-25MM.

ALSO...AS THE PANAMANIAN LOW DEEPENS...THIS WILL SUSTAIN THE
NORTHWARD MODULATION OF THE EASTERN PACIFIC ITCZ ACROSS COLOMBIA
INTO THE AZUERO PENINSULA IN PANAMA. UNDER FAVORABLE MJO
CONDITIONS ORGANIZED DEEP CONVECTION IS EXPECTED THROUGH
FRIDAY...WITH RAINFALL AMOUNTS OF 20-40MM/DAY AND MAXIMA OF
50-100MM. THROUGH SUNDAY THIS WILL DECREASE TO 15-20MM/DAY AND
MAXIMA OF 25-50MM. 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 40-80MM. 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
65W      68W    71W    72W    73W    74W    75W    77W     TUTT
INDCD.

THE TUTT INDUCED TROUGH MOVES ACROSS PUERTO RICO TO THE DOMINICAN
REPUBLIC EARLY IN THE CYCLE...WITH LOW LEVEL WINDS VEERING TO THE
SOUTHEAST AS IT RELOCATES ACROSS THE BASIN. THIS IS TO MEANDER
WEST TO THE CENTRAL CARIBBEAN...WHERE IT MERGES INTO AMPLIFYING
PANAMANIAN TROUGH. THE VEERING WINDS WILL SUSTAIN A SURGE IN PWAT
AMOUNTS AS DEEP ITCZ MOISTURE ADVECTS ACROSS THE LESSER ANTILLES.
EARLY IN THE CYCLE...IN POSSIBLE ECHO TRAINING...MODERATE TO HEAVY
CONVECTION IS FORECAST TO AFFECT THE WINDWARD ISLES WITH RAINFALL
AMOUNTS OF 15-30MM/DAY AND MAXIMA OF 50-100MM. NOTE THAT LOCALIZED
MAXIMA IN EXCESS OF FORECAST GUIDANCE IS HIGHLY POSSIBLE. ACROSS
THE FRENCH-LEEWARD/VIRGIN ISLES THIS IS TO THEN FAVOR RAINFALL
AMOUNTS OF 10-15MM/DAY AND MAXIMA OF 20-40MM. HIGH MOISTURE
CONTENT IS TO PERSIST THROUGH SATURDAY MORNING...WITH RAPID
EROSION EXPECTED DURING THE DAY AS A TRADE WINDS SURGE ENTERS THE
BASIN. OVER PUERTO RICO AND HISPANIOLA INITIALLY EXPECTING
RAINFALL AMOUNTS OF 10-15MM/DAY AND MAXIMA OF 20-45MM. ACROSS
HAITI-JAMAICA THIS INCREASES TO 15-20MM/DAY AND MAXIMA OF 25-50MM
DURING THE DAY ON SATURDAY. THIS IS TO ALSO FAVOR AN INCREASE IN
CONVECTION ACROSS EASTERN-CENTRAL VENEZUELA...WHERE WE EXPECT
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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