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AXPZ20 KNHC 240945
TWDEP

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
1005 UTC TUE NOV 24 2009

TROPICAL WEATHER DISCUSSION FOR THE EASTERN PACIFIC OCEAN FROM
THE EQUATOR TO 32N...EAST OF 140W.

BASED ON 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
0815 UTC.

...ITCZ...
AXIS ANALYZED FROM 08N82W TO 08N85W TO 06N91W TO 07N117W TO
06N123W TO 08N136W TO 07N140W. SCATTERED MODERATE ISOLATED
STRONG CONVECTION WAS WITHIN 80 NM OF AXIS FROM 106W TO 108W.
SCATTERED MODERATE CONVECTION WAS WITHIN 250 NM S OF AXIS E OF
87W.

...DISCUSSION...
A BROAD MID-UPPER LEVEL RIDGE PREVAILS ACROSS MUCH OF THE
FORECAST AREA. AN UPPER LEVEL TROUGH HAS ENTERED THE NW PART OF
THE FORECAST AREA WITH AXIS EXTENDING FROM 30N134W TO 22N140W.
ON THE EAST SIDE OF THE RIDGE AN UPPER LEVEL TROUGH IS FOUND
FROM CENTRAL TEXAS TO 20N102W. SUBSIDENCE IS OCCURRING IN BROAD
MID-UPPER CONVERGENCE ON BACK SIDE OF TROUGH ACROSS MOST OF NE
PORTIONS OF THE AREA. CONVECTION IS ALSO LIMITED ALONG THE ITCZ
W OF 87W...WHERE THERE IS ONLY ONLY WEAK CONVERGENT FLOW. THE
ONLY AREA OF CONVECTION W OF 87W IS NEAR 107W DUE TO A LOW LEVEL
TROUGH. THE LACK OF CONVECTION IN THE ITCZ WILL RESULT IN WEAKER
UPPER LEVEL RIDGING...AND ALLOW FOR THE UPPER LEVEL TROUGH JUST
ENTERING THE NW PORTION OF THE AREA TO MOVE ACROSS THE THE
FORECAST AREA...WITH THE TROUGH EVENTUALLY REACHING THE BAJA
PENINSULA AND INTENSIFYING BY EARLY THU.

...AT THE SURFACE...
HIGH PRESSURE 1027 MB CENTERED NEAR 36N131W MAINTAINS FRESH TO
STRONG TRADEWIND FLOW ACROSS MUCH OF THE W PORTION OF THE
AREA...WITH SEAS 9 TO 12 FT IN MIXED NW AND NE SWELLS. HIGH
PRESSURE WILL REMAIN N OF THE AREA...WHILE WEAKENING AND
EVENTUALLY DISSIPATING BY WED NIGHT. THE EASTWARD SHIFT OF THE
HIGH PRESSURE CENTER OVER THE PAST 24 HOURS HAS TIGHTENED THE
PRESSURE GRADIENT INTO GULF OF CALIFORNIA YIELDING A FRESH NORTH
BREEZE TO THE BASIN N OF 28N AS INDICATED IN ASCAT. LARGE LONG
PERIOD NW SWELL CONTINUES TO SPREAD S AND SE ACROSS MOST OF THE
EPAC W OF 115W. E OF 115W...SEAS WILL GENERALLY REMAIN 4 TO 6 FT
IN A MERGING LONG PERIOD SW AND NW SWELL. ANOTHER ROUND OF EVEN
LARGER LONG PERIOD NW SWELLS WILL MOVE INTO THE NW PORTION OF
THE AREA WED NIGHT...WITH SEAS REACHING NEAR 16 FT.

NLY GAP WINDS THROUGH THE GULF OF TEHUANTEPEC ARE FORECAST TO
BEGIN TONIGHT WITH WINDS NEAR 20 KT THROUGH WED MORNING BEFORE
BEGINNING TO INCREASE AND EXPAND IN AREAL COVERAGE AS ANOTHER
FRONTAL SYSTEM SINKS S ACROSS THE GULF OF MEXICO. GALE
CONDITIONS ARE EXPECTED IN THE GULF OF TEHUANTEPEC WED NIGHT.

$$

AL




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