[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 131057
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 AM EDT FRI MAR 13 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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1045 UTC.

...ITCZ...

THE ITCZ AXIS IS CENTERED ALONG 5N8W 2N15W CROSSING THE EQUATOR
NEAR 21W EXTENDING TO 4S30W INTO NE BRAZIL NEAR 6S38W. SCATTERED
MODERATE CONVECTION IS S OF 3N BETWEEN 11W-16W. SCATTERED
MODERATE/ISOLATED STRONG CONVECTION IS S OF 4N BETWEEN 17W-21W.
SCATTERED MODERATE CONVECTION IS FROM 1N-3N BETWEEN 22W-25W.

...DISCUSSION...

GULF OF MEXICO...
INCREASING SOUTHWESTERLY FLOW ALOFT IS PRESENT ACROSS THE
WESTERN GULF REGION. DEEP LAYER ATMOSPHERIC LIFT IN THIS FLOW IS
SUPPORTING A SURFACE STATIONARY FRONT IN THE W GULF THAT EXTENDS
FROM S LOUISIANA NEAR 30N93W TO 24N95W TO THE COAST OF MEXICO
NEAR 21N97W. LOW LEVEL CONVERGENCE AND DEEP LAYER ATMOSPHERIC
LIFT ARE SUPPORTING SCATTERED SHOWERS WITHIN 60 NM EITHER SIDE
OF THIS FRONT. TO THE NW OF THIS FRONT...N SURFACE WINDS OF 15
TO 20 KT ARE OCCURRING OVER THE NW GULF...WHERE A RELATIVELY
COOLER AND DRIER AIRMASS IS IN PLACE. THIS COOLER AIR IS OVER
RELATIVELY WARMER WATERS...RESULTING IN LAYERS OF SCATTERED TO
OVERCAST STRATOCUMULUS CLOUDS TO THE NW OF THE FRONT. TO THE SE
OF THE FRONT...DEEP LAYER DRY AIR IS RESULTING IN GENERALLY FAIR
WEATHER CONDITIONS ACROSS MUCH OF THE CENTRAL AND SE GULF. THE
FRONT IS FORECAST TO MOVE EASTWARD SLIGHTLY BY EARLY
SUNDAY...AND EXTEND FROM THE FLORIDA PANHANDLE TO THE WESTERN
BAY OF CAMPECHE.

CARIBBEAN SEA...
STRONG SURFACE HIGH PRESSURE BUILDING SOUTHWARD OVER THE W
ATLC WILL MAINTAIN MODERATE TO STRONG TRADES OVER MUCH OF THE
CARIBBEAN SEA THROUGH MONDAY. GENERALLY FAIR WEATHER CONDITIONS
ARE OCCURRING ACROSS MUCH OF THE CARIBBEAN REGION...WHERE DEEP
LAYER DRY AIR IS IN PLACE. HOWEVER...THE TRADE WINDS ARE
ADVECTING PATCHES OF LOW LEVEL MOISTURE WESTWARD ACROSS THE
CARIBBEAN...WITH SCATTERED SHOWERS EMBEDDED WITHIN THESE PATCHES
OF LOW LEVEL MOISTURE. THE GREATEST CONCENTRATION OF THESE
SHOWERS IS FROM 18N-21N BETWEEN 78W-83W. ALSO...INCREASED UPPER
LEVEL MOISTURE IS STREAMING NORTHEASTWARD ACROSS PORTIONS OF THE
SE CARIBBEAN.

ATLANTIC OCEAN...
INCREASING SOUTHWESTERLY FLOW ALOFT IS PRESENT ACROSS THE FAR W
ATLC. DEEP LAYER ATMOSPHERIC LIFT IN THIS FLOW IS SUPPORTING A
SURFACE STATIONARY FRONT EXTENDING FROM 31N81W TO 32N77W TO NE
OF THE DISCUSSION AREA. LOW LEVEL CONVERGENCE AND DEEP LAYER
ATMOSPHERIC LIFT ARE SUPPORTING SCATTERED SHOWERS WITHIN 60 NM
EITHER SIDE OF THIS FRONT. TO THE SE OF THIS FRONT...AN UPPER
LEVEL RIDGE IS IN PLACE...WITH A 1026 MB SURFACE HIGH NEAR
31N66W. DEEP LAYER DRY AIR AND ATMOSPHERIC STABILITY IN THE
VICINITY OF THE SURFACE HIGH AND UPPER LEVEL RIDGE ARE RESULTING
IN GENERALLY FAIR WEATHER CONDITIONS TO THE SE OF THE FRONT. AT
14/0600 UTC...THE SURFACE HIGH IS FORECAST TO HAVE DISSIPATED.
FARTHER TO THE E...AN UPPER LEVEL TROUGH IS N OF 20N BETWEEN
32W-46W...WITH AN UPPER LEVEL LOW NEAR 30N49W. THE UPPER LEVEL
LOW AND UPPER LEVEL TROUGH ARE ASSOCIATED WITH A 1000 MB SURFACE
LOW NEAR 29N42W...A DISSIPATING SURFACE COLD FRONT EXTENDING
FROM 18N45W TO 27N36W TO 32N36W TO NW OF THE DISCUSSION
AREA...AND A SURFACE OCCLUDED FRONT EXTENDING FROM 27N44W TO
29N44W TO 32N44W TO NE OF THE DISCUSSION AREA. THE SURFACE LOW
IS ASSOCIATED WITH GALE FORCE WINDS. ATMOSPHERIC INSTABILITY AND
LOW LEVEL CONVERGENCE NEAR THE SURFACE LOW AND SURFACE FRONTS
ARE SUPPORTING SCATTERED SHOWERS AND THUNDERSTORMS N OF 24N
BETWEEN 29W-43W. THIS ACTIVITY IS BEING SUPPORTED BY UPPER LEVEL
DIVERGENCE IN THE NE QUADRANT OF A 130-140 KT UPPER LEVEL JET
MAXIMUM LOCATED S OF THE UPPER LOW. THE SURFACE LOW IS FORECAST
TO BE POSITIONED NEAR 28N37W AS A 1006 MB SURFACE LOW AT 14/0600
UTC. FARTHER TO THE E...SUBSIDENCE ASSOCIATED WITH A SURFACE
RIDGE IS RESULTING IN FAIR WEATHER CONDITIONS ACROSS THE E ATLC.
ACROSS THE TROPICAL ATLC...AN UPPER LEVEL RIDGE IS S OF 15N E OF
54W WITH AN UPPER LEVEL HIGH NEAR 10N23W. UPPER LEVEL DIVERGENCE
ASSOCIATED WITH THE UPPER LEVEL HIGH AND UPPER LEVEL RIDGE IS
ENHANCING THE CONVECTION ASSOCIATED WITH THE ITCZ...AS WELL AS
SCATTERED SHOWERS FROM 1N-5N BETWEEN 1W-8W.

$$
COHEN




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