Prognostic Meteorological Discussion
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FXCA20 KWBC 261856
PMDCA

TROPICAL DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
256 PM EDT THU MAR 26 2015

DISCUSSION FROM MARCH 26/00 UTC:  LARGE LONG WAVE TROUGH CROSSING
THE PLAINS OF THE USA WILL BE THE FEATURE OF INTEREST FOR THE NEXT
SEVERAL DAYS. THIS TROUGH IS AMPLIFYING AS IT MOVES ACROSS THE
CENTRAL USA. THE ROBUST TROUGH IS SUSTAINING A POLAR HIGH AT
LOW-LEVELS AND IS ORGANIZING A FAST MOVING COLD FRONT. THE FRONT
AND ASSOCIATED CONVECTION WILL AFFECT MOST OF THE GULF OF MEXICO
BASIN-BAHAMAS AND THE GREATER ANTILLES INTO EARLY NEXT WEEK.

MODELS SHOW THE FRONT EXTENDING INTO NORTHERN VERACRUZ ON THURSDAY
EVENING...GULF OF CAMPECHE DURING FRIDAY MORNING...EXTREME
NORTHWESTERN BAHAMAS-NORTHERN YUCATAN-GULF OF CAMPECHE ON FRIDAY
EVENING WHEN TAIL WILL START TO BECOME ILL-DEFINED. ON SATURDAY
EVENING THE FRONT WILL EXTEND ACROSS THE CENTRAL AREAS OF THE
BAHAMAS-CUBA-YUCATAN. A 25-35KT NORTES EVENT WILL DEVELOP DURING
THURSDAY/FRIDAY...AND A TEHUANTEPECER JET DURING FRIDAY LASTING
INTO SATURDAY. FOCUS FOR LARGEST RAINFALL AMOUNTS WILL CONCENTRATE
ACROSS THE EASTERN/NORTHEASTERN SLOPES OF SOUTHEASTERN MEXICO ON
THURSDAY MIGRATING SOUTHEAST INTO NORTHERN
GUATEMALA/CHIAPAS/BELIZE/YUCATAN ON FRIDAY. BY THURSDAY INTO EARLY
FRIDAY EXPECTING AMOUNTS OF 20-40MM/DAY AND MAXIMA OF 50-100MM/DAY
ACROSS CENTRAL AND NORTHERN VERACRUZ. IN SOUTHERN VERACRUZ
EXPECTING MAXIMA OF 25-50MM/DAY. ACROSS TAMAULIPAS EXPECTING
ACCUMULATIONS OF 10-15MM/DAY AND ISOLATED MAXIMA OF 20-30MM/DAY.
BY FRIDAY INTO EARLY SATURDAY EXPECTING AMOUNTS OF 15-30MM/DAY AND
MAXIMA OF 40-80MM FROM CHIAPAS/SOUTHEASTERN VERACRUZ INTO
NORTHWESTERN HONDURAS/BELIZE/NORTHERN GUATEMALA. ACROSS THE
YUCATAN PENINSULA...PRE-FRONTAL/FRONTAL THUNDERSTORMS ARE TO
PRODUCE MAXIMA OF 20-40MM/DAY. LIGHT RAIN SHOWERS AND ISOLATED
THUNDERSTORMS WILL ALSO DEVELOP ACROSS SOUTHERN GUATEMALA/WESTERN
EL SALVADOR ON FRIDAY AFTERNOON TO PRODUCE ISOLATED MAXIMA OF
15MM. BY SATURDAY INTO EARLY SUNDAY EXPECTING AMOUNTS OF
15-20MM/DAY AND ISOLATED MAXIMA OF 35-70MM/DAY IN THE SAME REGION.

FRONT WILL ALSO ENHANCE ACTIVITY TO THE EAST ACROSS CUBA AND THE
BAHAMAS. THE ECMWF AND GFS MODELS ARE IN BETTER AGREEMENT THAN
YESTERDAY WITH RESPECT TO THE SPEED OF THE FRONT. THEY NOW SHOW IT
STALLING IN NORTHERN HISPANIOLA-SOUTHEASTERN CUBA-CAYMAN ISLANDS
DURING MONDAY AS IT WEAKENS. LARGEST AMOUNTS WILL ARRIVE AND
SPREAD DURING FRIDAY TO PRODUCE ACCUMULATIONS OF 10-15MM/DAY AND
MAXIMA OF 20-25MM/DAY INTO EARLY SATURDAY MORNING. AMOUNTS WILL
MIGRATE TO THE SOUTHEAST INTO SUNDAY WITH MOST WIDESPREAD ACTIVITY
LIKELY AFFECTING SOUTHEASTERN/CENTRAL CUBA...CENTRAL AND
SOUTHEASTERN BAHAMAS/TURKS AND CAICOS...AND THE CAYMAN ISLANDS
WHERE MAXIMA WILL REACH 15-30MM/DAY.

IN THE CARIBBEAN BASIN...MID-UPPER RIDGE WILL CONTINUE DOMINATING
MOST OF THE REGION. THE RIDGE IS SUSTAINING A STRONG SUBSIDENCE
CAP...WHICH IS PARTICULARLY STRONG ACROSS THE NORTHERN CARIBBEAN.
IN THE SOUTHERN CARIBBEAN...CAP IS WEAKER BUT PRESENT AND THE
DOMINANT LIMITING FACTOR IS THE DRY AIR PRESENT AT MID-LEVELS. TWO
WEAK AND WEAKENING EASTERLY WAVES CAN BE FOUND (SEE BELOW).
YET...ENHANCEMENT WILL BE LIMITED BY DRY AIR ENTRAINMENT. TO THE
SOUTHEAST...A MOISTURE PLUME HAS ESTABLISHED ALONG THE GUIANAS.
THIS WILL CONTINUE SUSTAINING CURRENTLY WETTER PATTERN ACROSS
FRENCH GUYANA AND MOSTLY SOUTH-CENTRAL SURINAME AND SOUTH-CENTRAL
GUYANA THROUGH FRIDAY...WITH A DRYING TREND AFTERWARDS. LARGEST
AMOUNTS WILL BE FOUND IN REGIONS OF ATLANTIC ITCZ CONVERGENCE
ALONG FRENCH GUIANA WITH MAXIMA IN THE 25-50MM/DAY RANGE THROUGH
EARLY FRIDAY...DECREASING TO MAXIMA OF 20-35MM/DAY AFTER.

ACROSS NORTHWESTERN SOUTH AMERICA...CONVECTION IS SLOWLY
ACTIVATING ACROSS COLOMBIA. EXPECTING A GRADUAL INCREASE IN
PRECIPITABLE WATER AND VENTILATION TO FAVOR A NORTHWARD EXPANSION
OF DIURNAL SHOWERS AND THUNDERSTORMS FROM THE CENTRAL ANDES INTO
PARTS OF THE CARIBBEAN COASTAL PLAINS AND EASTERN PANAMA.
EXPECTING MAXIMA IN THE 15-25MM/DAY RANGE THROUGH EARLY SATURDAY.
AN INCREASE IN AMOUNTS IS EXPECTED AFTERWARDS WITH MAXIMA REACHING
25-50MM/DAY.

ISOLATED CONVECTION IS ALSO EXPECTED IN COSTA RICA IN ASSOCIATION
WITH SEASONAL WARM WATER POOL TO THE SOUTH. EXPECTING LIGHT
RAINFALL AMOUNTS WHILE THE REGION STAYS UNDER THE INFLUENCE OF THE
MID-LEVEL RIDGE.

TROPICAL/EASTERLY WAVES INITIALIZED AT 12UTC
INITIAL  24     36     48     60     72     84     96        TYPE
69W     72W    75W     DISSIPATES                            EW
61W     64W    66W    68W    70W     DISSIPATES              EW

EASTERLY WAVE INITIALIZED AT 69W IS WEAKENING AS IT MOVES ACROSS
THE CENTRAL CARIBBEAN. THIS WAVE IS ENHANCING SHOWERS OVER OPEN
WATERS OF THE CARIBBEAN. ALTHOUGH ACTIVITY IS WEAKENING...IT WILL
STILL SLIGHTLY ENHANCE ACCUMULATIONS IN JAMAICA ON FRIDAY-SATURDAY
TO PRODUCE MAXIMA OF 10MM/DAY.

ANOTHER EASTERLY WAVE HAS FORMED AT 61W. THIS WAVE WILL ENHANCE
ACCUMULATIONS SLIGHTLY ACROSS THE WINDWARD ISLANDS ON THURSDAY TO
PRODUCE MAXIMA OF 10MM. IT WILL THEN WEAKEN AS IT MOVES ACROSS THE
SOUTHERN CARIBBEAN.

CRAIG...TTMS (TRINIDAD AND TOBAGO)
NANDA...MDS (SURINAME)
GALVEZ...WPC (USA)
$$




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