[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 062322
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
705 PM EST SAT DEC 06 2008

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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
2245 UTC.

...THE ITCZ...
THE ITCZ AXIS IS ANALYZED ALONG 7N10W 5N21W 3N32W 4N45W INTO N
BRAZIL NEAR 2N55W. SCATTERED MODERATE CONVECTION IS FROM 1N-6N
BETWEEN 18W-26W. SIMILAR CONVECTION IS FROM 1N-4N BETWEEN
27W-35W.

...DISCUSSION...

GULF OF MEXICO...
STRONG WESTERLY AND SOUTHWESTERLY FLOW ALOFT COVERS THE GULF
REGION IN THE BASE OF A VIGOROUS AND DEEP TROUGH OVER THE E
CONUS THAT EXTENDS ACROSS THE N GULF. AN ASSOCIATED SURFACE
STATIONARY FRONT IS PRESENT ACROSS THE GULF REGION...EXTENDING
FROM THE N FLORIDA PENINSULA NEAR 29N82W TO A 1016 MB SURFACE
LOW NEAR 29N85W TO 25N92W TO A 1018 MB SURFACE LOW IN THE BAY OF
CAMPECHE 21N95W. LOW LEVEL CONVERGENCE IN THE VICINITY OF THE
SURFACE LOWS AND STATIONARY FRONT...COMBINED WITH ATMOSPHERIC
LIFT IN MOIST WESTERLY AND SOUTHWESTERLY FLOW ALOFT...IS
SUPPORTING SCATTERED SHOWERS WITHIN 60 NM EITHER SIDE OF THE
FRONT. FOR LOCATIONS N AND W OF THE FRONT...THE NORTHERLY
COMPONENT OF THE SURFACE WINDS IS ADVECTING A RELATIVELY COOLER
AND DRIER AIRMASS ACROSS THE N AND W GULF REGION. DURING THE
NEXT DAY...THE APPROACH OF A STRONG MID/UPPER-LEVEL JET
MAXIMUM...CURRENTLY OVER THE PLAINS OF THE CONUS...WILL HELP
PUSH MUCH OF THE FRONT SOUTHWARD AS A COLD FRONT. DEEP LAYER DRY
AIR AND CONFLUENT FLOW ALOFT ARE INHIBITING DEEP CONVECTION OVER
THE SE GULF...WHERE GENERALLY FAIR WEATHER PREVAILS.

CARIBBEAN SEA...
AN UPPER RIDGE AXIS IS OVER THE LEEWARD AND WINDWARD ISLANDS...
WITH SOUTHERLY AND SOUTHWESTERLY FLOW ALOFT TO THE W OF THE
RIDGE AXIS COVERING MUCH OF THE CARIBBEAN. AS A RESULT...
MID/UPPER LEVEL MOISTURE IS STREAMING ACROSS THE W CARIBBEAN...
WITH SCATTERED SHOWERS OVER THE SW CARIBBEAN S OF 13N W OF 76W.
THIS ACTIVITY IS BEING ENHANCED BY LOW LEVEL CONVERGENCE IN THE
VICINITY OF A 1009 MB SURFACE LOW IN NW COLOMBIA NEAR 8N76W.
FAIR WEATHER PERSISTS ACROSS MUCH OF THE E CARIBBEAN...WHERE
STABLE ATMOSPHERIC CONDITIONS AND DEEP LAYER DRY AIR ARE
INHIBITING DEEP CONVECTION. NE TO E SURFACE WINDS OF 15 TO 20
KT...EXCEPT TO 25 KT ALONG THE COAST OF COLOMBIA...ARE PRESENT
ACROSS THE CARIBBEAN.

ATLANTIC OCEAN...
A VIGOROUS AND DEEP TROUGH IS PRESENT OVER THE E CONUS AND
N GULF...WITH STRONG SOUTHWESTERLY FLOW ALOFT ACROSS THE W ATLC.
A SURFACE STATIONARY FRONT EXTENDS FROM THE N FLORIDA PENINSULA
NEAR 29N82W TO 30N80W TO A NEWLY-DEVELOPED 1014 MB SURFACE LOW
NEAR 32N78W TO NE OF THE DISCUSSION AREA. THIS NEWLY-DEVELOPED
SURFACE LOW IS BEING SUPPORTED BY STRONG ATMOSPHERIC LIFT
ASSOCIATED WITH UPPER LEVEL DIVERGENCE IN THE VICINITY OF A 110
TO 120 KT UPPER LEVEL JET MAXIMUM OVER THE W ATLC. LOW LEVEL
CONVERGENCE IS SUPPORTING SCATTERED SHOWERS WITHIN 60 NM EITHER
SIDE OF THE STATIONARY FRONT. THIS ACTIVITY IS BEING ENHANCED BY
THE UPPER LEVEL DIVERGENCE ASSOCIATED WITH THE UPPER LEVEL JET
MAXIMUM OVER THE W ATLC. TO THE E OF THE STATIONARY FRONT...A
NEWLY-DEVELOPED SURFACE TROUGH...EXTENDING FROM 28N72W TO THE
BAHAMAS NEAR 23N75W TO NE OF CUBA NEAR 20N74W...IS ADDED TO THE
06/2100 UTC SURFACE ANALYSIS. A RECENT ASCAT PASS INDICATES
CYCLONIC CURVATURE IN THE LOW LEVEL WIND FIELD NEAR THIS SURFACE
TROUGH. LOW LEVEL CONVERGENCE IS SUPPORTING SCATTERED SHOWERS
WITHIN 60 NM EITHER SIDE OF THIS SURFACE TROUGH. FARTHER TO THE
E...AN UPPER RIDGE AXIS EXTENDS FROM THE LEEWARD AND WINDWARD
ISLANDS TO 29N61W... AND AN UPPER TROUGH AXIS EXTENDS FROM
16N40W TO 25N40W TO 32N38W TO NE OF THE DISCUSSION AREA. THIS
UPPER TROUGH IS ASSOCIATED WITH A 1014 MB SURFACE LOW NEAR
26N46W...A 1015 MB SURFACE LOW NEAR 26N35W...A SURFACE TROUGH
EXTENDING FROM 30N43W TO 24N44W TO 20N51W...AND A SURFACE TROUGH
EXTENDING FROM 21N39W TO 18N42W TO 14N43W. LOW LEVEL CONVERGENCE
NEAR THESE SURFACE LOWS AND SURFACE TROUGHS IS SUPPORTING
SCATTERED SHOWERS N OF 14N BETWEEN 31W-45W. OVER THE TROPICAL
ATLC...AN UPPER RIDGE IS S OF 10N BETWEEN THE AFRICAN COAST AND
51W...WITH AN UPPER HIGH NEAR 6N24W AND AN UPPER HIGH NEAR
4N48W. UPPER LEVEL DIVERGENCE ASSOCIATED WITH THE UPPER RIDGE
AND UPPER HIGHS IS ENHANCING THE CONVECTION ASSOCIATED WITH THE
ITCZ.

$$
COHEN


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