[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 130519
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 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 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
0445 UTC.

...ITCZ...

THE ITCZ AXIS IS CENTERED ALONG 4N7W 3N15W CROSSING THE EQUATOR
NEAR 22W EXTENDING TO 5S30W INTO NE BRAZIL NEAR 6S39W. SCATTERED
MODERATE CONVECTION IS FROM 1N-3N BETWEEN 10W-12W. SCATTERED
MODERATE/ISOLATED STRONG CONVECTION IS S OF 3N BETWEEN 13W-20W.

...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 COLD FRONT THAT EXTENDS FROM S LOUISIANA
NEAR 30N93W TO 26N95W TO THE W GULF NEAR 22N97W...AND A SURFACE
STATIONARY FRONT THAT EXTENDS FROM 22N97W TO THE COAST OF MEXICO
NEAR 22N98W. LOW LEVEL CONVERGENCE AND DEEP LAYER ATMOSPHERIC
LIFT ARE SUPPORTING SCATTERED SHOWERS WITHIN 60 NM EITHER SIDE
OF THE SURFACE COLD AND STATIONARY FRONTS. TO THE NW OF THESE
FRONTS...N AND NE SURFACE WINDS OF 15 TO 20 KT ARE OCCURRING...
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 FRONTS. TO THE SE OF THE FRONTS...DEEP LAYER DRY AIR IS
RESULTING IN GENERALLY FAIR WEATHER CONDITIONS ACROSS MUCH OF
THE CENTRAL AND SE GULF. THE COLD FRONT IS FORECAST TO MOVE
EASTWARD ACROSS THE MIDDLE GULF SAT THROUGH SUN AND EXTEND FROM
THE FLORIDA PANHANDLE TO THE WESTERN BAY OF CAMPECHE BY MONDAY
AND THEN DISSIPATE ON TUESDAY.

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 15N-18N BETWEEN 76W-80W. 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 31N82W TO 31N78W TO
32N74W 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 31N68W. 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 14/0000 UTC...THE SURFACE HIGH IS FORECAST
TO HAVE DISSIPATED. FARTHER TO THE E...AN UPPER LEVEL TROUGH IS
N OF 23N BETWEEN 35W-52W...WITH AN UPPER LEVEL LOW NEAR 30N42W.
THE UPPER LEVEL LOW AND UPPER LEVEL TROUGH ARE ASSOCIATED WITH A
1000 MB SURFACE LOW NEAR 29N43W...A DISSIPATING SURFACE COLD
FRONT EXTENDING FROM 18N45W TO 27N37W TO 32N37W TO NW OF THE
DISCUSSION AREA...AND A SURFACE OCCLUDED FRONT EXTENDING FROM
31N44W TO 32N43W TO NE OF THE DISCUSSION AREA. ATMOSPHERIC
INSTABILITY AND LOW LEVEL CONVERGENCE NEAR THE SURFACE LOW AND
SURFACE FRONTS ARE SUPPORTING SCATTERED SHOWERS AND
THUNDERSTORMS N OF 22N BETWEEN 32W-44W. 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
1005 MB SURFACE LOW AT 14/0000 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 52W WITH AN UPPER
LEVEL HIGH NEAR 10N25W. 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 2W-7W.

$$
COHEN




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