Skip Navigation Links weather.gov 
NOAA logo - Click to go to the NOAA homepage National Weather Service   NWS logo - Click to go to the NWS homepage
The Weather Prediction Center
 
Tropical Discussion
 
(Latest Discussion - Issued 1830Z May 22, 2018)
 
Version Selection
Versions back from latest:  0   1   2   3   4   5   6   7   8   9   10   
 
Abbreviations and acronyms used in this product


TROPICAL DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
230 PM EDT TUE MAY 22 2018

TROPICAL DISCUSSION FROM MAY 22/12 UTC: WEST OVER THE DOMAIN...AT
500 HPA...A HIGH TO THE SOUTHWEST OF COLIMA/NAYARIT MEXICO EXTENDS
A LOW AMPLITUDE RIDGE ACROSS CENTRAL/NORTHERN MEXICO. OVER THE
NEXT FEW DAYS THIS RIDGE IS FORECAST TO BUILD NORTH ACROSS TEXAS
INTO THE CENTRAL USA. AS THE RIDGE BUILDS...IT IS TO STEER A SHORT
WAVE TROUGH ACROSS THE CENTRAL GULF TO THE YUCATAN
PENINSULA...WHERE IT MERGES WITH REMNANTS OF AN OLD PERTURBATION
TO THE EAST. THIS WILL THEN EVOLVE INTO A NEGATIVELY TILTED TROUGH
WITH AXIS SOUTHEAST FROM THE NORTHWEST GULF...ACROSS THE YUCATAN
TO THE WESTERN CARIBBEAN/CENTRAL AMERICA. THIS PATTERN IS TO THEN
HOLD THROUGH FRIDAY MORNING. AT LOW LEVELS...THE DEEPENING TROUGH
WILL INDUCE THE NORTHWARD AMPLIFICATION OF A TROUGH ACROSS THE
WESTERN CARIBBEAN TO THE EASTERN GULF OF MEXICO. THIS IS TO
GRADUALLY BECOME BETTER ORGANIZED LATER IN THE WEEK...WITH THE NHC
MONITORING THIS FEATURE FOR POSSIBILITY OF A TROPICAL/ SUBTROPICAL
CYCLONE FORMING ALONG THIS AXIS BETWEEN THE NORTHWEST
CARIBBEAN-SOUTHEAST GULF OF MEXICO.

MEANWHILE...AS IT MEANDERS OVER THE WESTERN CARIBBEAN...THE TUTT
INDUCED PERTURBATION WILL ENHANCE LOW LEVEL MOISTURE
CONVERGENCE...ACROSS THE NORTHWEST CARIBBEAN ISLES. OVER THE
CAYMAN ISLANDS INITIALLY EXPECTING RAINFALL AMOUNTS OF 35-70MM/DAY
AND MAXIMA OF 150-200MM. ON WEDNESDAY EXPECTING ADDITIONAL
RAINFALL AMOUNTS OF 20-30MM/DAY AND MAXIMA OF 40-80MM...WHILE ON
THURSDAY-FRIDAY EXPECT ACCUMULATION OF 15-20MM/DAY AND MAXIMA OF
25-50MM. OVER WESTERN CUBA HEAVY RAINS ARE TO PERSIST THROUGH THE
END OF THE WEEK. INITIALLY EXPECTING ACCUMULATION OF 35-70MM/DAY
AND MAXIMA OF 15-20MM. ON WEDNESDAY-FRIDAY THIS INCREASES TO
50-100MM/DAY AND MAXIMA OF 150-250MM/DAY. OVER JAMAICA THIS IS TO
FAVOR RAINFALL AMOUNTS OF 10-15MM/DAY AND MAXIMA OF 20-40MM...WITH
MOST ACTIVE TODAY. LATER ON THURSDAY-FRIDAY EXPECTING RAINFALL
AMOUNTS OF 05-10MM/DAY AND MAXIMA OF 15-20MM. THE MEANDERING
TROUGH IS TO ALSO ENHANCE MOISTURE CONVERGENCE ACROSS THE YUCATAN
PENINSULA-BELIZE...WITH RAINFALL AMOUNTS OF 15-20MM/DAY AND MAXIMA
OF 35-70MM. ON WEDNESDAY-THURSDAY EXPECTING ADDITIONAL RAINFALL
AMOUNTS OF 10-15MM/DAY AND MAXIMA OF 20-45MM IN AFTERNOON
CONVECTION...WHILE ON FRIDAY THE MAXIMA IS TO PEAK AT 20-35MM.

IN A DEEP LAYER SOUTH-SOUTHWESTERLY FLOW...THE LOW/MID LEVEL
TROUGH SUSTAINS THE NORTHWARD MODULATION OF THE ITCZ ACROSS
SOUTHERN NICARAGUA/COSTA RICA TO THE SOUTHERN CARIBBEAN-NORTHERN
COLOMBIA. AS THE TROUGH BECOMES BETTER ORGANIZED...A MOIST
SOUTHWESTERLY FLOW IS TO ESTABLISH ACROSS NICARAGUA TO GULF OF
FONSECA/EL SALVADOR ON THURSDAY. THIS WILL FAVOR A GRADUAL
INCREASE IN DIURNAL CONVECTION AS MOISTURE CONVERGES ALONG THE
CONTINENTAL DIVIDE. EARLY IN THE CYCLE EXPECTING RAINFALL AMOUNTS
OF 10-15MM/DAY AND MAXIMA OF 20-40MM/DAY. ON THURSDAY-FRIDAY THIS
INCREASES TO 20-30MM/DAY AND MAXIMA OF 50-100MM/DAY. OVER SOUTHERN
NICARAGUA/COSTA RICA...ALONG THE ITCZ...EXPECTING RAINFALL AMOUNTS
OF 15-20MM/DAY AND MAXIMA OF 30-60MM. THIS WANES ON
WEDNESDAY...WITH ACCUMULATION OF 10-15MM/DAY AND MAXIMA OF
20-35MM...WHILE ON THURSDAY IT SURGES TO 15-20MM/DAY AND MAXIMA OF
30-60MM. ACROSS EASTERN NICARAGUA/NORTHEAST HONDURAS INITIALLY
EXPECTING RAINFALL AMOUNTS OF 20-30MM/DAY AND MAXIMA OF 40-80MM.
ON WEDNESDAY AND ONWARD EXPECTING ADDITIONAL RAINFALL AMOUNTS OF
10-15MM/DAY AND MAXIMA OF 20-35MM/DAY. OVER NORTHERN
COLOMBIA/NORTHWEST VENEZUELA...MEANWHILE...THIS WILL RESULT IN
RAINFALL AMOUNTS OF 20-30MM/DAY AND MAXIMA OF 40-80MM. ON
WEDNESDAY MAXIMA PEAKS AT 35-70...WHILE ON THURSDAY-FRIDAY
EXPECTING ACCUMULATION OF 10-15MM/DAY AND MAXIMA OF 20-35MM. ON
THE ANDEAN REGION/WESTERN COASTAL PLAINS OF COLOMBIA EXPECTING
RAINFALL AMOUNTS OF 05-10MM/DAY AND MAXIMA OF 15-20MM. ON
THURSDAY...UNDER INFLUENCE OF A TROPICAL WAVE...THIS INCREASES TO
10-15MM/DAY AND MAXIMA OF 20-35MM. ON THE PIEDEMONTE
LLANERO/AMAZONIA IN EASTERN COLOMBIA-AMAZONIA IN SOUTHERN
VENEZUELA EXPECTING RAINFALL AMOUNTS OF 20-30MM/DAY AND MAXIMA OF
40-80MM. THROUGH THURSDAY/FRIDAY THIS DECREASES TO 15-20MM/DAY AND
MAXIMA OF 30-60MM.

A MID/UPPER LEVEL RIDGE LIES TO THE EAST...DOMINATING THE FLOW
OVER THE WESTERN ATLANTIC WHILE ANCHORING ON A 500 HPA HIGH NEAR
30N 68W. POLAR TROUGH EXITING THE EASTERN USA ON WEDNESDAY IS TO
THEN PRESS AGAINST THIS AXIS...LEADING TO GRADUAL EROSION OF MID
LEVEL RIDGE PATTERN ON WEDNESDAY-THURSDAY. A TUTT TO THE EAST
ORIGINATES ON A CLOSED LOW NEAR 22N 58W...WITH AXIS TRAILING TO
THE EASTERN CARIBBEAN-NORTHERN VENEZUELA. AS THE RIDGE TO THE WEST
WEAKENS...THE TUTT IS FORECAST TO GRADUALLY PULL TO THE NORTHEAST.
MEANWHILE...THE MEANDERING MID/UPPER LEVEL TROUGH IS TO FAVOR AN
ELEVATED TRADE WINDS CAP ACROSS THE NORTHEAST CARIBBEAN ISLES. AT
LOW LEVELS...BROAD RIDGE IS TO DOMINATE THE FLOW ACROSS THE
ATLANTIC BASIN-CARIBBEAN SEA...WHILE CENTERING AT 850 HPA ON A
MEANDERING CLOSED HIGH NEAR 30N 50W. ACROSS THE EASTERN-CENTRAL
CARIBBEAN THIS FAVORS A TIGHT GRADIENT AND BRISK EASTERLY
TRADES...FORECAST TO PEAK AT 15-20KT OVER THE NEXT COUPLE OF DAYS.
THIS WILL ADVECT A PLUME OF SHALLOW MOISTURE ACROSS THE NORTHEAST
CARIBBEAN LATER TODAY...WHERE IT IS EXPECTED TO PERSIST THROUGH
THE END OF THE WEEK. SLIGHTLY STRONGER WINDS ARE EXPECTED OVER THE
ABC ISLES/OFF THE COAST OF COLOMBIA...WITH WINDS PEAKING AT
20-25KT. OVER PUERTO RICO-HISPANIOLA SHALLOW DIURNAL CONVECTION IS
TO RESULT IN RAINFALL AMOUNTS OF 05-10MM/DAY AND MAXIMA OF
15-20MM. THROUGH THURSDAY THIS INCREASES TO 10-15MM/DAY AND MAXIMA
OF 20-45MM. OVER THE VIRGIN ISLES AND THE LESSER ANTILLES ISLES
EXPECTING RAINFALL AMOUNTS OF 05-10MM/DAY AND MAXIMA OF 15MM/DAY
DURING THE NEXT TWO DAYS...WITH LESSER AMOUNTS OF THURSDAY AS A
DRYER AIR MASS ENTRAINS FROM THE EAST.

THE TROUGH ALOFT CONTINUES TO PRESS AGAINST A CELL OF THE
SUBEQUATORIAL RIDGE TO THE SOUTH. DURING THE NEXT FEW DAYS THE
UPPER LEVEL RIDGE IS TO CONFINE TO AREA EAST OF 50W WHILE
CENTERING ON A CLOSED HIGH NEAR 10N 35W. THIS RIDGE IS VENTING
DIURNAL CONVECTION ACROSS THE GUIANAS. IN THIS AREA INITIALLY
EXPECTING RAINFALL AMOUNTS OF 05-10MM/DAY AND MAXIMA OF 15-20MM
ALONG THE COAST...WHILE ALONG THE NEAR EQUATORIAL TROUGH TO THE
SOUTH EXPECTING RAINFALL AMOUNTS OF 15-20MM/DAY AND MAXIMA OF
25-50MM. THROUGH THURSDAY MORNING...UNDER INFLUENCE OF A TROPICAL
WAVE...ACTIVITY TO THE NORTH INCREASES TO 15-20MM/DAY AND MAXIMA
OF 25-50MM. ON THURSDAY-FRIDAY THIS WILL FAVOR ADDITIONAL RAINFALL
AMOUNTS OF 15-20MM/DAY AND MAXIMA OF 30-60MM.

TROPICAL/EASTERLY WAVES/TRADE WIND SURGES INITIALIZED AT 12UTC:
INITIAL 24    36    48    60    72    84    96        TYPE      
SOF
40W     42W   44W   47W   50W   52W   54W   56W        TW       
14N
67W     69W   72W   74W   76W   78W   80W   82W        TW       
15N
86W     87W   88W   88W   88W   87W   88W   87W     TUTT INDCD  
26N

A TROPICAL WAVE ALONG 40W AND SOUTH OF 14N ENTERS FRENCH GUIANA
EARLY ON THURSDAY MORNING...TO FAVOR RAINFALL AMOUNTS OF
15-20MM/DAY AND MAXIMA OF 25-50MM. THIS IS TO QUICKLY SPREAD
ACROSS SURINAME DURING THE DAY. THROUGH FRIDAY THIS INCREASES TO
15-20MM/DAY AND MAXIMA OF 30-60MM.

A TROPICAL WAVE ALONG 67W AND SOUTH OF 15N...AS IT MOVES TO
WESTERN VENEZUELA/ EASTERN COLOMBIA LATER TODAY...IS TO SUSTAIN
RAINFALL AMOUNTS OF 20-30MM/DAY AND MAXIMA OF 40-80MM. ON
WEDNESDAY IT IS TO THEN ENHANCE ITCZ/NET CONVECTION ACROSS
NORTHERN COLOMBIA TO FAVOR RAINFALL AMOUNTS OF 15-20MM/DAY AND
MAXIMA OF 35-70MM...WHILE ON THE ANDEAN REGION TO THE WEST
EXPECTING RAINFALL AMOUNTS OF 05-10MM/DAY AND MAXIMA OF 15-20MM.
ON THURSDAY...ACTIVITY OVER NORTHERN COLOMBIA AND PANAMA WILL
RESULT IN RAINFALL AMOUNTS OF 10-15MM/DAY AND MAXIMA OF 20-35MM.
AS IT MOVES TO COSTA RICA ON FRIDAY...IN INTERACTION WITH THE
ITCZ...EXPECTING RAINFALL AMOUNTS OF 20-30MM/DAY AND MAXIMA OF
40-80MM.

THE TUTT OVER THE GULF/WESTERN CARIBBEAN SUSTAINS AN INDUCED
TROUGH IN THE EASTERLY TRADES WITH AXIS ALONG 86W TO 26N. SEE
ABOVE FOR DETAILS/RAINFALL AMOUNTS.

HUDSON...MS (JAMAICA)
NIXON...BDM (THE BAHAMAS)
DAVISON...WPC (USA)