TROPICAL DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
402 PM EDT FRI SEP 20 2019

AT 18 UTC HURRICANE JERRY CENTERED NEAR 19.2N 61.2W...WITH MAXIMUM
SUSTAINED WINDS OF 70KT AND CENTRAL PRESSURE OF 990 HPA. THE TS IS
MOVING TO THE WEST-NORTHWEST AT 15KT.

AT 18 UTC HURRICANE LORENA CENTERED NEAR 22.9N 109.4W... WITH
MAXIMUM SUSTAINED WINDS OF 65KT AND CENTRAL PRESSURE OF 987 HPA.
THE STORM IS MOVING TO THE WEST AT 05KT.

AT 18 UTC TROPICAL STORM MARIO CENTERED NEAR 17.9N 110.1W...WITH
MAXIMUM SUSTAINED WINDS OF 55KT AND CENTRAL PRESSURE OF 994 HPA.
THE STORM IS MOVING TO THE NORTH-NORTHEAST AT 04KT.

TROPICAL DISCUSSION FROM SEP 20/12 UTC: NORTHWEST IN THE
DOMAIN...AN UPPER RIDGE CENTERS OVER THE EASTERN PACIFIC INTO
NORTHERN MEXICO AND SOUTH TEXAS. THIS UPPER RIDGE IS STRENGTHENING
OVER WESTERN MEXICO/SOUTHERN GULF OF CALIFORNIA BY THE LATENT HEAT
PRODUCED BY THE CONVECTION OF HURRICANES LORENA AND MARIO. THE
RIDGE IS FORECAST TO SLOWLY MEANDER NORTHEASTWARD...TO CENTER ON A
HIGH OVER SOUTH TEXAS BY SUNDAY EVENING AND INTO MONDAY. THIS WILL
ALLOW THE ARRIVAL OF A TUTT FROM THE GULF OF MEXICO INTO CENTRAL
PARTS OF THE COUNTRY ON MONDAY. AT LOW-LEVELS...SOUTHWESTERLY
WINDS ASSOCIATED WITH THE ITCZ AND HURRICANES LORENA AND MARIO ARE
TRANSPORTING TROPICAL MOISTURE INTO THE GULF OF CALIFORNIA AND THE
SIERRA MADRE OCCIDENTAL. THIS WILL SUSTAIN A SEASONALLY ACTIVE
PATTERN OF AFTERNOON/EVENING CONVECTION IN THE REGION ON A DAILY
BASIS. LARGEST ACCUMULATIONS ARE EXPECTED...HOWEVER...IN EXTREME
SOUTHERN BAJA CALIFORNIA AS HURRICANE LORENA CROSSES THE REGION ON
FRIDAY. THROUGH EARLY SATURDAY...EXPECTING ACCUMULATIONS OF
25-50MM/DAY AND MAXIMA OF 100-150MM. ALONG NORTHERN SINALOA AND
SOUTHERN SONORA EXPECTING 15-20MM/DAY AND MAXIMA OF 25-50MM. BY
SATURDAY-EARLY SUNDAY EXPECTING 15-30MM/DAY AND MAXIMA OF 40-80MM
IN THE CENTRAL GULF OF CALIFORNIA. IN NORTHERN MEXICO...UNDER THE
INFLUENCE OF AN ENHANCED DIVERGENT PATTERN AS AN UPPER TROUGH
MOVES FROM THE WEST...EXPECTING 10-15MM/DAY AND MAXIMA OF 20-40MM.
BY SUNDAY-MONDAY...LARGEST ACCUMULATIONS ARE EXPECTED IN CENTRAL
BAJA CALIFORNIA WHERE AMOUNTS ARE FORECAST TO REACH 15-20MM/DAY
AND MAXIMA OF 25-50MM. IN THE SIERRA MADRE OCCIDENTAL EXPECTING
10-15MM/DAY AND MAXIMA OF 20-40MM.

IN THE CARIBBEAN...A SYSTEM OF CONCERN IS HURRICANE JERRY (SE NHC
FOR TRACK AND INTENSITY). JERRY IS FORECAST TO PASS NORTH OF THE
LEEWARD ISLANDS LATE ON FRIDAY AND WELL NORTH OF PUERTO RICO AND
THE VI ON SATURDAY. EXTREME RAINFALL FROM THE SYSTEM WILL NOT
IMPACT THE ISLANDS DIRECTLY. FEEDER BAND
CONVECTION...HOWEVER...WILL SUSTAIN ACCUMULATIONS OF 15-20MM/DAY
AND MAXIMA OF 25-50MM. ISOLATED HIGHER AMOUNTS ARE EXPECTED IN THE
NORTHERN LEEWARDS.

ANOTHER REGION OF INTEREST IN THE CARIBBEAN ARE
HISPANIOLA/JAMAICA/CUBA AND THE BAHAMAS. AT UPPER LEVELS...AN
ELONGATED TROUGH EXTENDS ACROSS THE NORTHWEST BAHAMAS INTO
HONDURAS. THIS TROUGH IS INTERACTING WITH A MOIST PLUME THAT
EXTENDS ACROSS THE CENTRAL CARIBBEAN INTO HISPANIOLA. THIS PLUME
ORIGINATED FROM A TROPICAL WAVE...BUT HAS NOW STALLED IN THE
REGION AS IT IS INTERACTING WITH THE UPPER TROUGH. ALSO AT LOW
LEVELS...A SURFACE FRONT HAS FORMED ACROSS THE NORTH ATLANTIC AND
EXTENDS ACROSS THE EXTREME NORTHWEST BAHAMAS INTO THE FLORIDA
STRAIT. THE FRONT IS AN ADDITIONAL SOURCE OF LOW-LEVEL MOISTURE
CONVERGENCE...AND IS SUSTAINING SCATTERED DEEP CONVECTION IN THE
BAHAMAS AS IT INTERACTS WITH THE UPPER TROUGH. THE EXPECTED
EVOLUTION IS FOR THE UPPER TROUGH TO SLOWLY MEANDER WESTWARD TO
EXTEND ACROSS THE EASTERN GULF OF MEXICO INTO THE YUCATAN
PENINSULA BY SUNDAY EVENING. THIS WILL ALLOW FOR THE MOIST PLUME
AND ASSOCIATED CONVECTION TO MEANDER SLOWLY WESTWARD AS
WELL...MAINTAIN AN ACTIVE PATTERN OF DEEP CONVECTION AND GUSTY
WINDS IN THE BAHAMAS AND PARTS OF CUBA. UNDER THE PRESENCE OF COLD
AIR ALOFT...ENHANCED INSTABILITY...UPPER JET DYNAMICS AND STRONG
15-25KT TRADES...EXPECTING PERIODS WITH ISOLATED SEVERE CONVECTION
AND LARGE RAINFALL RATES. IN TERMS OF ACCUMULATIONS...ON
FRIDAY...LARGEST AMOUNTS ARE EXPECTED IN SOUTHERN HISPANIOLA WHERE
EXPECTING 25-50MM/DAY AND MAXIMA OF 75-125MM. IN THE BAHAMAS
EXPECTING 15-20MM/DAY AND MAXIMA OF 25-50MM WITH THE RISK OF
ISOLATED SEVERE CONVECTION. IN CUBA AND JAMAICA EXPECTING
10-15MM/DAY AND MAXIMA OF 20-40MM. BY SATURDAY INTO
SUNDAY...EXPECTING LARGEST ACCUMULATIONS IN THE CENTRAL BAHAMAS
WHERE EXPECTING MAXIMA OF 15-20MM/DAY AND MAXIMA OF 35-70MM. IN
CUBA...JAMAICA AND HISPANIOLA EXPECTING 10-15MM/DAY AND MAXIMA OF
20-40MM. BY SUNDAY-MONDAY...LARGEST AMOUNTS ARE EXPECTED IN CUBA
AND THE NORTHERN BAHAMAS...WHERE AMOUNTS WILL REACH 15-20MM/DAY
AND MAXIMA OF 30-60MM. IN HISPANIOLA...A FEEDER BAND IN
ASSOCIATION WITH JERRY WILL STIMULATE CONVECTION TO SUSTAIN
15-20MM/DAY AND MAXIMA OF 30-60MM.

FINALLY...A PERTURBATION IN THE TRADES WILL ARRIVE INTO THE
WINDWARD ISLANDS LATE ON SATURDAY. THIS WILL SUSTAIN LOCALLY HEAVY
RAINFALL. EXPECTING MAXIMA RAMPING UP TO 35-70MM/DAY BY
SATURDAY/SUNDAY. THIS WILL PEAK ON SUNDAY TO MONDAY...WHEN MAXIMA
WILL REACH 75-100MM/DAY.

IN CENTRAL AMERICA...CONVECTION IS FORECAST TO ACTIVATE THROUGH
THE CYCLE. THE AFOREMENTIONED UPPER TROUGH MEANDERING FROM THE
GULF OF HONDURAS ON FRIDAY TOWARDS CHIAPAS/TABASCO ON
SUNDAY...WILL DRAW THE ITCZ NORTHWARD INTO THE GULF OF FONSECA AND
ALONG THE WEST COAST OF NICARAGUA AND COSTA RICA BY SUNDAY. THIS
WILL ENHANCE THE CONVERGENCE OF WESTERLY WINDS AND PRECIPITATION.
THE GDI AND RAINFALL FORECASTS FROM MODELS AGREE ON THIS.
YET...THE MODEL FORECAST RAINFALL AMOUNTS APPEAR STILL A BIT
CONSERVATIVE. BY FRIDAY THROUGH EARLY SATURDAY EXPECTING
25-50MM/DAY AND MAXIMA OF 75-125MM IN SOUTHERN COSTA RICA/WESTERN
PANAMA. ACROSS WESTERN NICARAGUA INTO CHIAPAS EXPECTING
10-15MM/DAY AND MAXIMA OF 20-40MM. ISOLATED LARGER AMOUNTS ARE
EXPECTED IN THE GULF OF FONSECA REGION. BY
SATURDAY-SUNDAY...EXPECTING MAXIMA OF 50-100MM/DAY IN WESTERN
PANAMA AND WESTER COSTA RICA. IN THE GULF OF FONSECA REGION
EXPECTING MAXIMA OF 40-80MM. BY SUNDAY-MONDAY...LARGEST AMOUNTS
WILL CLUSTER IN THE GULF OF FONSECA REGION AND INTO SOUTHERN
GUATEMALA WHERE EXPECTING MAXIMA OF 50-100MM. IN COSTA RICA AN
PANAMA EXPECTING 15-20MM/DAY AND ISOLATED MAXIMA OF 30-60MM.

IN NORTHERN SOUTH AMERICA...MOST ACTIVE WILL BE INITIALLY IN
COLOMBIA. A MESOSCALE CONVECTIVE SYSTEM HAS FORMED EAST OF THE
ANDES AND WILL SUSTAIN MAXIMA OF 75-125MM IN CENTRAL COLOMBIA ON
FRIDAY. HOWEVER...CONVECTION WILL CONTINUE TO BE STIMULATED IN THE
LAKE MARACAIBO REGION...SANTANDERES...AND CHOCO/VALLE DEL CAUCA
WHERE EXPECTING 15-30MM/DAY AND MAXIMA OF 40-80MM THROUGH EARLY
SATURDAY. BY SATURDAY-SUNDAY EXPECTING SIMILAR AMOUNTS FROM LAKE
MARACAIBO INTO THE EJE CAFETERO AND CHOCO. EAST OF THE
ANDES...EXPECTING A DECREASE TO 10-15MM/DAY AND MAXIMA OF 20-40MM.

TROPICAL/EASTERLY WAVES/TRADE WIND SURGES FROM 00 UTC:
INITIAL 24    36    48    60    72    84    96     TYPE    SOF
51W    53W   55W   57W   59W   61W   63W   64W     EW     19N

A PERTURBATION IN THE ITCZ/EASTERLY WAVE IS PROPAGATING NORTH OF
THE GUIANAS ON FRIDAY...AND IS FORECAST TO REACH GUYANA ON
SATURDAY...AND TRINIDAD AND TOBAGO/NORTHEASTERN VENEZUELA ON
SUNDAY. THIS WILL SUSTAIN HEAVY RAINFALL ESPECIALLY IN THE
WINDWARD ISLANDS FROM SATURDAY THROUGH MONDAY. THE NHC IS
MONITORING THIS PERTURBATION FOR DEVELOPMENT.

AMPARO...ONAMET (DOMINICAN REPUBLIC)
USECHE...IDEAM (COLOMBIA)
GALVEZ...WPC (USA)