Prognostic Meteorological Discussion
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FXCA20 KWBC 241713
PMDCA

TROPICAL DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1213 PM EST WED DEC 24 2014

LAST NO AMENDS. NEXT ON MONDAY DECEMBER 29.

DISCUSSION FROM DECEMBER 24/00UTC: HIGH AMPLITUDE POLAR TROUGH
EXTENDS ACROSS THE CENTRAL USA/MEXICO TO THE EASTERN PACIFIC. THE
TROUGH IS FORECAST TO RAPIDLY WEAKEN THROUGH THURSDAY EVENING AS
IT LIFTS OVER A RIDGE TO THE EAST. EARLY IN THE CYCLE...AS THE
TROUGH MEANDERS OVER MEXICO-EASTERN PACIFIC...IT IS TO SHEAR A
CLOSED LOW TO THE SOUTH-SOUTHWEST OF COLIMA. THIS IS TO GRADUALLY
WEAKEN THROUGH THURSDAY MORNING WHILE SHEARING SHORT WAVE ENERGY
NORTHWARD ACROSS THE SOUTHWEST-CENTRAL STATES. THIS WILL BE ENOUGH
TO TRIGGER ISOLATED TO SCATTERED CONVECTION ACROSS
COLIMA-NAYARIT-SIERRA MADRE DEL SUR...WHERE WE EXPECT RAINFALL
AMOUNTS OF 05-10MM/DAY AND MAXIMA OF 15-25MM. AT LOW LEVELS...THE
TROUGH ALOFT SUSTAINS A SURFACE FRONT THAT MOVES ACROSS CENTRAL
FLORIDA TO THE YUCATAN PENINSULA LATER THIS EVENING. FRONTAL
NORTHERLIES OF 25-30KT ARE TO ACCOMPANY THIS BOUNDARY AS IT ENTERS
SOUTHERN MEXICO/THE YUCATAN. THROUGH THURSDAY MORNING IT IS TO
MOVE ACROSS SOUTH FLORIDA TO THE YUCATAN/BELIZE...AND ON THURSDAY
EVENING IT ENTERS THE NORTHWEST BAHAMAS-WESTERN TIP OF CUBA
TRAILING TO BELIZE. BUT AS THE UPPER TROUGH PULLS...THE FRONT IS
TO STALL AND THEN RETROGRESS ACROSS FLORIDA INTO THE GULF OF
MEXICO DURING THE DAY ON FRIDAY. THE FRONT AND STRONG FRONTAL
NORTHERLIES ARE TO  TRIGGER MODERATE TO HEAVY CONVECTION ACROSS
CHIAPAS/TABASCO-CAMPECHE-NORTHERN OAXACA-SOUTHERN VERACRUZ THROUGH
WEDNESDAY EVENING...WITH ACCUMULATION OF 15-20MM/DAY AND MAXIMA OF
35-70MM/DAY. ACROSS WESTERN CUBA EXPECTING ACCUMULATION OF
15-20MM/DAY AND MAXIMA OF 25-50MM...WITH THE MOST INTENSE TO
CLUSTER OVER YOUTH ISLAND. OVER THE NORTHWEST BAHAMAS THIS IS TO
THEN FAVOR RAINFALL AMOUNTS OF 00-05MM/DAY AND MAXIMA OF 10MM ON
THURSDAY TO FRIDAY. OVER NORTHWEST HONDURAS-NORTHEAST
GUATEMALA...THE FRONTAL NORTHERLIES ARE TO ENHANCE CONVECTIVE
DEVELOPMENT ON WEDNESDAY AFTERNOON TO MIDDAY ON THURSDAY...WITH
RAINFALL AMOUNTS OF 10-15MM/DAY AND MAXIMA OF 20-40MM.

MID/UPPER LEVEL RIDGE TO THE EAST EXTENDS ACROSS THE CARIBBEAN
BASIN TO THE WESTERN ATLANTIC. AT 500 HPA IT IS TO ANCHOR ON A
CLOSED HIGH OVER THE TURKS AND CAICOS/SOUTHEAST BAHAMAS EARLY IN
THE CYCLE...THAT IS TO MEANDER TO THE NORTHWEST BAHAMAS LATER THIS
WEEK. AS IT PERSISTS...THE RIDGE IS TO SUSTAIN A SUBSIDENCE CAP
ACROSS THE CARIBBEAN BASIN-NORTHERN SOUTH AMERICA. IN THIS
PATTERN...FAIR WEATHER CONDITIONS ARE TO PREVAIL ACROSS MOST OF
THE CARIBBEAN-NORTHERN SOUTH AMERICA. AT LOW LEVELS...A HIGH
PRESSURE RIDGE TO THE SOUTH-SOUTHEAST OF BERMUDA SUSTAINS A BRISK
EASTERLY FLOW ACROSS THE CARIBBEAN BASIN. OVER THE NORTHERN
CARIBBEAN THE 850 HPA WINDS ARE TO PEAK AT 20-25KT...WHILE OVER
THE SOUTHERN CARIBBEAN EXPECTING WINDS OF 30-35KT. THIS RAPIDLY
EXPANDS ACROSS NICARAGUA INTO THE EASTERN PACIFIC THROUGH FRIDAY
MORNING...WITH WINDS PEAKING AT 40-45KT. IN A NORTHEASTERLY COOL
ADVECTIVE PATTERN...THIS RIDGE IS TO FAVOR EARLY MORNING SHALLOW
CONVECTION ACROSS THE LEEWARD-VIRGIN ISLES-PUERTO RICO INTO
EASTERN HISPANIOLA...WITH RAINFALL AMOUNTS OF 00-05MM/DAY AND
ISOLATED MAXIMA OF 10MM.

AS THE TRADES SURGE ACROSS THE SOUTHERN CARIBBEAN-CENTRAL
AMERICA...THIS IS TO FAVOR MOISTURE CONVERGENCE ON THE CARIBBEAN
PLAINS OF NICARAGUA...TO RESULT IN RAINFALL AMOUNTS OF 05-10MM/DAY
AND MAXIMA OF 15MM. OTHER CONVECTION IS EXPECTED TO THE SOUTH
ALONG THE ANDEAN REGION AND WESTERN PLAINS OF COLOMBIA...WITH
RAINFALL AMOUNTS OF 00-05MM/DAY AND MAXIMA OF 10MM. LOCALLY HIGHER
AMOUNTS ARE EXPECTED ON THE CAUCA VALLEY...WHERE ITCZ CONVERGENCE
IS TO FAVOR MAXIMA OF 15MM.

DOWNSTREAM FROM THE SUBTROPICAL RIDGE...OVER THE ATLANTIC...A LONG
WAVE TROUGH EXTENDS SOUTH ALONG 40W/45W TO AMAPA IN BRASIL/AMAZON
RIVER DELTA REGION. THE GUIANAS ARE TO REMAIN ON THE CONVERGENT
SIDE OF THIS TROUGH AND THE BROAD RIDGE TO THE WEST. AT LOW
LEVELS...THE ITCZ IS TO MEANDER WEST ACROSS THE SOUTHERN GUIANAS
TO SOUTHERN AMAZONAS IN VENEZUELA. IN A MID/UPPER CONVERGENT
PATTERN THIS IS TO ONLY FAVOR SHALLOW CONVECTION...WITH MOST
ACTIVE ALONG THE NORTHERN GUIANAS TO RESULT IN RAINFALL AMOUNTS OF
05-10MM/DAY AND MAXIMA OF 15MM. SIMILAR AMOUNTS ARE EXPECTED
ACROSS TRINIDAD/TOBAGO-NORTHEAST VENEZUELA...WHERE SHEAR LINE
CONFLUENCE IS TO PERSIST OVER THE NEXT FEW DAYS. THE SHEAR LINE IS
TO SUSTAIN LOW LEVEL MOISTURE CONVERGENCE TO FAVOR RAINFALL
AMOUNTS OF 05-10MM/DAY AND MAXIMA OF 10MM.

TROPICAL/EASTERLY WAVES INITIALIZED AT 12UTC
INITIAL  24     36     48     60     72     84     96     TYPE

NONE.

JN BAPTISTE...MS (SAINT LUCIA)
NANDA...MDS (SURINAME)
DAVISON...WPC (USA)
$$




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