[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 171815
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
105 PM EST SAT DEC 17 2005

TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL
AMERICA...GULF OF MEXICO...CARIBBEAN SEA...NORTHEASTERN SECTIONS
OF SOUTH AMERICA...AND ATLANTIC OCEAN TO THE AFRICAN COAST FROM
THE EQUATOR TO 32N. THE FOLLOWING INFORMATION IS BASED ON
SATELLITE IMAGERY...WEATHER OBSERVATIONS...RADAR...AND
METEOROLOGICAL ANALYSIS.

BASED ON 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1115 UTC.

...ITCZ...

ITCZ 8N10W 6N20W 4N30W 3N40W 2N50W. SCATTERED MODERATE TO
ISOLATED STRONG SHOWERS AND THUNDERSTORMS FROM 5N TO 9N
BETWEEN 32W AND 37W. ISOLATED TO WIDELY SCATTERED MODERATE
SHOWERS/LOCALLY STRONG THUNDERSTORMS ELSEWHERE FROM 3N TO 10N
BETWEEN 20W AND 60W.

...DISCUSSION...

THE GULF OF MEXICO...
A MIDDLE TO UPPER LEVEL TROUGH IS ALONG 100W NOW NORTH OF 20N
RIGHT OVER TEXAS. THE SUBTROPICAL JET RIDES ALONG THE EASTERN
SIDE OF THE TROUGH FROM NORTHEASTERN MEXICO ALONG THE TEXAS COAST
TOWARD THE SOUTHERN APPALACHIAN MOUNTAINS WITH CORE SPEEDS OF AT
LEAST 100 KT IN THE GULF WATERS. THIS IS PRODUCING MODERATE
UPPER LEVEL SOUTHWESTERLY FLOW OVER THE GULF WATERS. THE COLD
FRONT WHICH PUSHED THROUGH THE AREA DURING THE PAST COUPLE OF
DAYS HAS BEEN MOVING NORTHWESTWARD AS A WARM FRONT. IT NOW RUNS
FROM LAKE OKEECHOBEE TO THE EASTERN GULF WATERS...TO THE CENTRAL
GULF...TO A 1012 MB WEST CENTRAL GULF OF MEXICO LOW PRESSURE
CENTER. A STATIONARY FRONT EXTENDS FROM THE LOW CENTER TO THE
ISTHMUS OF TEHUANTEPEC. FAIR SKIES ARE SOUTH OF 25N81W 24N88W
21N91W. THE STATIONARY FRONT EXTENDS S OF THE LOW INTO THE BAY
OF CAMPECHE SEPARATING COOL CONTINENTAL AIR OVER MEXICO FROM
WARM TROPICAL AIR OVER THE GULF. SCATTERED MODERATE TO STRONG
SHOWERS AND THUNDERSTORMS ARE IN THE NORTH CENTRAL GULF WATERS
NORTH OF 24N BETWEEN 86W AND 95W. THE FRONT WILL CONTINUE TO
LIFT TO THE NORTH TODAY AND THEN BECOME STATIONARY THIS EVENING
FROM NORTH FLORIDA TO THE WESTERN GULF...THEN MOVE LITTLE DURING
THE NEXT FEW DAYS. THIS WILL ENHANCE THE CHANCES FOR SHOWERS
OVER THE GULF WATERS AND FLORIDA AT LEAST UNTIL THURSDAY.

THE CARIBBEAN SEA...
AN UPPER LEVEL ANTICYCLONE IS CENTERED NEAR EASTERN PANAMA AND
NORTHWESTERN COLOMBIA. A RIDGE EXTENDS NORTHWARD TO THE WINDWARD
PASSAGE AND THEN NORTHEASTWARD INTO THE WESTERN ATLANTIC OCEAN.
MIDDLE TO UPPER LEVEL DRY AIR DOMINATES THE ENTIRE AREA BENEATH
THE ANTICYCLONE. HIGH LEVEL CLOUDS ARE CURVING ANTICYCLONICALLY
FROM GUATEMALA/EL SALVADOR/HONDURAS INTO THE CARIBBEAN SEA WEST
OF 80W...WITH A COMPARATIVELY SMALLER AMOUNT OF HIGH CLOUDS EVEN
REACHING THE WATERS BETWEEN 70W AND 80W. LITTLE CHANGE IS
EXPECTED IN THE OVERALL PATTERN EXCEPT THAT AN INCREASE IN
MOISTURE ACROSS THE NORTHWESTERN CARIBBEAN SEA BEGINNING SUNDAY
NIGHT MAY RAISE THE CHANCE FOR SHOWERS.

THE ATLANTIC OCEAN...
UPPER LEVEL ANTICYCLONIC FLOW COVERS THE ATLANTIC WATERS NORTH
OF 20N WEST OF 55W. A NORTHEAST-TO-SOUTHWEST ORIENTED UPPER
LEVEL RIDGE IS ALONG THE LINE FROM 32N68W TO THE CENTRAL
BAHAMAS. A JET STREAM STILL IS RIDING AROUND THE NORTHERN
SIDE OFF THE U.S.A. MIDDLE ATLANTIC COAST. THE COLD FRONT WHICH
MOVED INTO THE WESTERN ATLANTIC YESTERDAY HAS LIFTED NORTHWARD
AS A WARM FRONT. A STATIONARY FRONT CONNECTS THE SOUTHERN POINT
OF A COLD FRONT NEAR 32N69W TO THE EASTERN POINT OF THE WARM
FRONT NEAR 30N78W. A TROUGH MARKS A ROPE CLOUD FEATURE ON
VISIBLE SATELLITE IMAGERY ALONG 31N69W 30N71W 28N73W. STRONG
SUBSIDENCE ASSOCIATED WITH THE UPPER RIDGE ONLY HAS ALLOWED
ISOLATED OVERRUNNING SHOWERS ALONG THE EASTERN COAST OF FLORIDA.
SURFACE HIGH PRESSURE IS IN CONTROL OVER MUCH OF THE WESTERN AND
CENTRAL ATLANTIC BETWEEN 50W AND 70W WITH SCATTERED/BROKEN
STRATOCUMULUS COVERING THE AREA. A LARGE AND ELONGATED UPPER LOW
IS LOCATED SOUTHWEST OF THE AZORES NEAR 30N36W WITH A TROUGH
EXTENDING TO 22N48W AND TO THE LESSER ANTILLES. THE SUBTROPICAL
JET TO THE SE OF THE TROUGH EXTENDS FROM 13N50W NORTHEASTERN TO
SOUTHERN MOROCCO WITH CORE SPEEDS NEAR 110 KT. THIS IS PRODUCING
A BROKEN BAND OF HIGH CIRRUS OVER THE TROPICS AND SPREADING
ACROSS THE CAPE VERDE ISLANDS TO WEST AFRICA. A SURFACE
TROUGH...POSSIBLY A LATE SEASON TROPICAL WAVE...LIES ALONG
43W/44W SOUTH OF 12N AND MOVING WEST 10 TO 15 KT. ANY
PRECIPITATION APPEARS TO BE MORE THAN ANYTHING WITH THE ITCZ.
HIGH CLOUDS ARE LIFTING TO THE NORTHEAST WITH THE UPPER LEVEL
SOUTHWESTERLY WIND FLOW...BETWEEN 36W AND 44W. POSSIBLE SHOWERS
ARE FOUND FROM 10N TO 13N BETWEEN 40W AND 50W...NOT TOO PRECISE.
A 1012 MB LOW PRESSURE CENTER IS NEAR 28N35W...AND A 1013 MB LOW
PRESSURE CENTER IS NEAR 27N23W. SCATTERED MODERATE SHOWERS AND
POSSIBLE THUNDERSTORMS ARE FOUND FROM 29N TO 33N BETWEEN 32W AND
37W. SCATTERED MODERATE SHOWERS TO ISOLATED STRONG THUNDERSTORMS
ARE FOUND FROM 27N TO 31N BETWEEN 22W AND 32W. A LINE OF BROKEN
LOW TO MIDDLE LEVEL CLOUDS MARKS A SURFACE TROUGH FROM THE
1012 MB LOW CENTER TO 24N40W 26N43W 30N45W. THE LOW AND TROUGH
ARE EXPECTED TO CONSOLIDATE DURING THE NEXT FEW DAYS AND LIFT
NORTHEASTWARD TOWARD THE MADEIRA ISLANDS...THEN DROP SOUTHWARD
TOWARD THE CANARY ISLANDS BY WEDNESDAY.

$$
MT

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