459
FXCA20 KWBC 231825
PMDCA
TROPICAL DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
224 PM EDT TUE OCT 23 2018
AT 15 UTC HURRICANE WILLA CENTERED NEAR 21.4N 106.9W..WITH MAXIMUM
SUSTAINED WINDS OF 110KT AND MINIMAL CENTRAL PRESSURE OF 966KT.
THE HURRICANE IS MOVING NORTH-NORTHEAST AT 5KT. SEE NHC DISCUSSION
FOR OFFICIAL FORECAST.
TROPICAL DISCUSSION FROM OCT 23/12 UTC: CONSISTENT WITH PREVIOUS
ANALYSIS AND FORECAST...A 500 HPA HIGH OVER THE NORTHERN YUCATAN
ANCHORS A RIDGE THAT EXTENDS FROM EASTERN MEXICO/THE GULF...TO THE
GREATER ANTILLES/NORTHERN CARIBBEAN. THE MID LEVEL RIDGE PATTERN
IS EXPECTED TO PERSIST DURING THE NEXT THREE DAYS. AS IT HOLDS
OVER THE GREATER ANTILLES-NORTHERN CENTRAL AMERICA...THE MID LEVEL
RIDGE PATTERN IS TO SUSTAIN A TRADE WINDS CAP. THE CAP INVERSION
IS TO INHIBIT ORGANIZED DEEP CONVECTION. ACROSS PUERTO RICO AND
JAMAICA...SHALLOW CONVECTION IS TO INITIALLY TRIGGER RAINFALL
AMOUNTS OF 05-10MM/DAY AND MAXIMA OF 15MM. THIS DECREASES TO
00-05MM/DAY AND ISOLATED MAXIMA OF 10MM ON WEDNESDAY AND ONWARD.
THE MID LEVEL RIDGE...AS IT HOLDS...IS STEERING HURRICANE WILLA TO
THE NORTHEAST...WITH THE NHC FORECASTING THE HURRICANE TO LANDFALL
BETWEEN SOUTHERN SINALOA AND NAYARIT LATER TODAY. THIS IS TO THEN
WEAKEN AS IT LIFTS ACROSS DURANGO TO COAHUILA/TAMAULIPAS ON
WEDNESDAY. MEANWHILE...EXPECTING HEAVY RAINFALL AMOUNTS TO AFFECT
SOUTHERN SINALOA-NAYARIT-SOUTHWEST DURANGO...WITH ACCUMULATION
RANGING BETWEEN 150-350MM. DUE TO STRONG TOPOGRAPHICAL
FORCING...EXPECTING LOCALIZED MAXIMA OF AROUND 500MM. ACROSS
EASTERN DURANGO-SOUTHERN COAHUILA-NORTHERN ZACATECAS THIS IS TO
TRIGGER SCATTERED CONVECTION WITH RAINFALL AMOUNTS OF 10-15MM/DAY
AND MAXIMA OF 20-35MM EARLY ON WEDNESDAY.
LATER ON WEDNESDAY...AS THE REMNANTS OF THE CYCLONE LIFT ACROSS
NORTHEAST MEXICO...IT IS TO COMBINE WITH AN AMPLIFYING MID/UPPER
LEVEL TROUGH STREAMING ACROSS TEXAS. MODELS THEN SHOW FORMATION OF
AN EXTRATROPICAL CYCLONE/FRONTAL LOW OVER SOUTH TEXAS/NORTHWEST
GULF OF MEXICO. THE LOW IS TO RAPIDLY INTENSIFY AS IT MIGRATES
ACROSS THE NORTHERN GULF TO THE SOUTHEASTERN USA...DRIVING A FRONT
SOUTH ACROSS NORTHEAST MEXICO TO VERACRUZ/CENTRAL MEXICO LATER ON
THURSDAY. AS IT RACES ACROSS NORTHEAST MEXICO...THIS IS TO SUSTAIN
SCATTERED CONVECTION ACROSS TAMAULIPAS WITH RAINFALL AMOUNTS OF
05-10MM/DAY AND MAXIMA OF 15MM ON WEDNESDAY...INCREASING TO
10-15MM/DAY AND MAXIMA OF 20-40MM ACROSS VERACRUZ ON THURSDAY.
NORTH OF THE MID LEVEL RIDGE...OVER THE WESTERN ATLANTIC...POLAR
TROUGH LIES NORTH OF THE ISLANDS. THE TROUGH IS EXPECTED TO
GRADUALLY LIFT TO THE NORTH-NORTHEAST EARLY IN THE CYCLE. AS IT
PULLS AWAY...ASSOCIATED SURFACE FRONT WILL LOSE ITS UPPER LEVEL
SUPPORT...WITH BOUNDARY TO WEAKEN TO A TROUGH AS IT MEANDERS
ACROSS THE NORTHWEST BAHAMAS. THE TROUGH IS TO THEN ENHANCE LOW
LEVEL MOISTURE CONVERGENCE...WITH PWAT CONTENT PEAKING AROUND 50MM
ON WEDNESDAY. OVER THE NORTHWEST BAHAMAS INITIALLY EXPECTING
RAINFALL AMOUNTS OF 05-10MM/DAY AND MAXIMA OF 15-25MM. ON
WEDNESDAY THIS WILL INCREASE TO 10-15MM/DAY AND MAXIMA OF
20-35MM...WHILE ON THURSDAY EXPECTING ADDITIONAL RAINFALL AMOUNTS
OF 05-10MM/DAY AND MAXIMA OF 15MM.
FARTHER TO THE EAST OF THIS FEATURE...A TUTT EXTENDS OVER THE
CENTRAL ATLANTIC...WITH AXIS SOUTH ALONG 60W TO THE ISLAND
CHAIN/NORTHEAST VENEZUELA. THIS TROUGH IS FORECAST TO LIFT TO THE
EAST-NORTHEAST ON WEDNESDAY AS AHEAD OF A DEEPENING MID/UPPER
LEVEL TROUGH TO THE WEST. MEANWHILE...AS IT MEANDERS ACROSS THE
ISLAND CHAIN...THIS IS TO INTERACT WITH THE NEAR EQUATORIAL TROUGH
OVER VENEZUELA-COLOMBIA. IN THIS AREA EXPECTING RAINFALL AMOUNTS
OF 15-20MM/DAY AND MAXIMA OF 25-50MM. ON WEDNESDAY...AS THE TROUGH
PULLS...THIS DECREASES TO 05-10MM/DAY AND MAXIMA OF
15-20MM...WHILE ON THURSDAY THE MAXIMA PEAKS AT 20-30MM.
OVER WESTERN COLOMBIA...UNDER THE INFLUENCE OF THE PANAMANIAN
LOW...MOISTURE IS TO CONVERGE ALONG THE WEST COAST TO THE EJE
CAFETERO. IN THIS AREA EXPECTING RAINFALL AMOUNTS OF 10-15MM/DAY
AND MAXIMA OF 20-40MM/DAY...WITH PEAK IN ACTIVITY ON WEDNESDAY.
OVER COSTA RICA/SOUTHERN NICARAGUA-PANAMA...ITCZ RELATED
CONVERGENCE WILL SUSTAIN RAINFALL AMOUNTS OF 05-10MM/DAY AND
MAXIMA OF 15-25MM/DAY.
TROPICAL/EASTERLY WAVES/TRADE WIND SURGES FROM 00 UTC:
INITIAL 24 36 48 60 72 84 96 TYPE SOF
91W 94W 97W 99W 103W 105W 107W 110W EW 19N
AN EASTERLY WAVE ALONG 91W AND SOUTH OF 19N IS TO TRIGGER ISOLATES
TO SCATTERED CONVECTION AS IT STREAMS ACROSS SOUTHERN TO CENTRAL
MEXICO EARLY IN THE CYCLE...FAVORING RAINFALL AMOUNTS OF
00-05MM/DAY AND MAXIMA OF 10MM. OVER SOUTHWEST MEXICO THIS
INCREASES TO 05-10MM/DAY AND MAXIMA OF 15MM ON WEDNESDAY.
SERNA...IDEAM (COLOMBIA)
TEJADA...AAC (PANAMA)
DAVISON...WPC (USA)
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