[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 051743
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
105 PM EST MON JAN 05 2009

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

BASED ON 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1715 UTC.

...THE ITCZ...

ITCZ IS CENTERED ALONG 6N10W 2N20W TO EQUATOR AT 30N TO 1S50W.
SCATTERED MODERATE CONVECTION IS WITHIN 100 NM EITHER SIDE OF
AXIS E OF 20W. SIMILAR CONVECTION IS NEAR 3N43W.

...DISCUSSION...

GULF OF MEXICO...
AS OF 1500 UTC...A WEAK SFC LOW HAS DEVELOPED ALONG THE FRONTAL
SYSTEM OVER THE GULF WATERS NEAR 26N96W. A COLD FRONT EXTENDS
FRONT THE LOW SWD ACROSS THE FAR W GULF ENTERING MEXICO JUST N
OF TAMPICO. A STATIONARY FRONT ALSO STRETCHES FROM THE LOW
CENTER TO SE LOUISIANA. A ROPE CLOUD DELINEATES THE LEADING EDGE
OF THE COLD FRONT WHILE DOPPLER RADAR SHOWS SCATTERED SHOWERS
AND ISOLATED TSTMS ALONG THE FRONTAL BOUNDARY. THE FRONT IS
EXPECTED TO DRIFT SE OVER THE NW GULF THROUGH TUE THEN WILL MOVE
RAPIDLY ACROSS THE REGION ON WED REACHING SOUTH FLORIDA AND THE
YUCATAN PENINSULA LATE WED. MODERATE TO STRONG NW-N WINDS OF 20
TO 30 KT WILL FOLLOW THE FRONT. UNTIL THEN...LIGHT TO MODERATE
SE FLOW AND MAINLY FAIR WEATHER WILL LIKELY CONTINUE OVER MUCH
OF THE GULF REGION COURTESY OF A RIDGE AT THE SURFACE AND ALOFT.
TAMPICO REPORTED NLY WINDS OF 20 KT AROUND 1700 UTC INDICATING
THE PASSAGE OF THE COLD FRONT.

CARIBBEAN...
HIGH PRES N OF AREA IS PRODUCING MODERATE TO FRESH TRADE WINDS
ACROSS THE BASIN. A RECENT QSCAT PASS SHOWED THE STRONGEST WINDS
OF 20 TO 30 KT NEAR THE COAST OF COLOMBIA. AN AMPLIFIED
MID-UPPER LEVEL RIDGE DOMINATES THE WEST AND CENTRAL CARIBBEAN
EXTENDING NW FROM AN UPPER HIGH NEAR BLUEFIELDS NICARAGUA. AN
UPPER-LEVEL TROUGH IS OVER THE FAR E CARIBBEAN. UNDER THIS
PATTERN... WIDESPREAD DRY STABLE AIR IS OBSERVED ON WATER VAPOR
IMAGERY... ESPECIALLY WITHIN THE RIDGE. HOWEVER...AS USUAL
LOW-LEVEL INSTABILITY IS PRODUCING PATCHES OF LOW CLOUDS WITH
EMBEDDED LIGHT SHOWERS ACROSS THE AREA. A WEAK SFC TROUGH IS
ALONG 74W. NE WINDS AHEAD OF THIS TROUGH ARE TRANSPORTING SOME
LOW LEVEL MOISTURE WITH ISOLATED TO SCATTERED SHOWERS ACROSS
WESTERN PANAMA AND COSTA RICA. OTHERWISE LITTLE SIGNIFICANT
CHANGE IS EXPECTED OVER THE NEXT COUPLE OF DAYS. A WEAKENING
COLD FRONT IS FORECAST TO APPROACH THE YUCATAN CHANNEL ON THU.

ATLANTIC...
THE MID-UPPER PATTERN IS NEARLY WLY AND QUITE STRONG ACROSS THE
ATLC BASIN...WITH A COUPLE OF WEAK EMBEDDED SHORT WAVE TROUGHS
AND RIDGES. MULTILAYERED CLOUDS WITH EMBEDDED SHOWERS ARE N OF
20N BETWEEN 50W AND 70W...MAINLY AHEAD OF A SHORT WAVE TROUGH
WHICH LIES ALONG 60W/61W. A JET-STREAM BRANCH WITH CORE WINDS OF
90-100 KT IS ON THE WEST SIDE OF THIS TROUGH ENTERING THE AREA
NEAR 31N72W THEN CROSSING JUST N OF THE N LEEWARD ISLANDS INTO
THE TROPICAL N ATLC. AT THE SURFACE...A WEAK LOW-LEVEL TROUGH
HAS DEVELOPED ACROSS THE W ATLC AND THE SE BAHAMAS WITH AXIS
ALONG 74W/75W. VIS SATELLITE IMAGERY REVEALS ISOLATED SHOWERS
EITHER SIDE OF THE TROUGH AXIS. ANOTHER LOW-LEVEL TROUGH EXTENDS
FROM 31N45W TO 23N56W ENHANCING SOME SHOWER ACTIVITY.
OTHERWISE...SFC HIGH PRES COVERS THE FORECAST AREA ANCHORED BY A
1029 MB CENTER NEAR 33N28W AND A 1023 MB NEAR 29N67W. E WINDS OF
15 TO 20 KT ARE BLOWING ACROSS THE PERIPHERY OF THESE HIGHS OVER
THE DEEP TROPICS.

$$
GR





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