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000
AXPZ20 KNHC 091559 CCA
TWDEP

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
1605 UTC MON NOV 09 2009

REMOVED TROPICAL LOW SECTION.

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

BASED ON 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1500 UTC.

...ITCZ...

THE INTERTROPICAL CONVERGENCE ZONE IS ALONG THE LINE...07N77W TO
07N105W TO 10N115W TO 08N140W. SCATTERED MODERATE WITH ISOLATED
STRONG CONVECTION IS WITHIN 100 NM OF THE POINT 10.5N112.5W.
SCATTERED MODERATE CONVECTION IS WITHIN 60 NM OF THE POINT
09.5N116W AND ALSO THE POINT 14N116W. SCATTERED MODERATE WITH
ISOLATED STRONG CONVECTION IS WITHIN 100 NM OF THE POINT
11N121.5W.

...DISCUSSION...

A MOSTLY UPPER TROUGH EXTENDS ACROSS THE AREA WITH AN AXIS FROM
SOUTHERN TEXAS ACROSS MEXICO TO SOUTHERN BAJA CALIFORNIA TO
18N130W THEN SOUTH TO THE ITCZ NEAR 135W. NORTH AND WEST OF THIS
TROUGH AXIS TO A LINE FROM THE BIG BEND OF THE RIO GRANDE TO
22N140W THE ATMOSPHERE IS DRY AND CLOUD FREE IN THE MIDDLE AND
UPPER LEVELS. NORTH OF THIS DRY AREA SOME UPPER MOISTURE IS
PRESENT WITH SOME THIN SCATTERED UPPER CLOUDS. THROUGHOUT MOST
OF THIS AREA NORTH OF THE TROUGH AXIS THE LOWER LEVELS ARE
COVERED BY BROKEN TO OVERCAST STRATOCUMULUS CLOUDS. A DRY MIDDLE
AND UPPER LAYER AREA IS OVER NORTHERN MEXICO NORTH OF 28.5N. W
OF 105W SOUTH OF A LINE FROM 20N105W TO 20N123W TO THE ITCZ AT
140W A PLUME OF UPPER MOISTURE IS BEING ADVECTED NORTHEASTWARD
FROM ITCZ CONVECTION MULTI LEVEL BROKEN TO OVERCAST CLOUDS WITH
SOME EMBEDDED CONVECTION. THE CONVECTION IS CONFINED TO SOUTH OF
15N.

A SHARP MOSTLY UPPER TROUGH CONTINUES FROM THE WESTERN GULF OF
MEXICO ACROSS THE EASTERN PART OF THE ISTHMUS OF TEHUANTEPEC
ALONG ABOUT 91W CONTINUING TO THE ITCZ NEAR 91W. THE AREA OVER
THE OCEAN AND MEXICO WEST OF THE TROUGH AXIS TO 105W IS DRY AND
CLOUD FREE IN THE MIDDLE AND UPPER LEVELS. OVER SOUTHERN
GUATEMALA SOME LOW TO MIDDLE CLOUDS WITH SOME EMBEDDED LOW
TOPPED CONVECTION IS NOTED. THIS CONVECTION IS ASSOCIATED WITH A
WEAK LOW THAT HAS BEEN OFF THE COAST OF GUATEMALA FOR THE LAST
SEVERAL DAYS AND IS FORECAST TO CONTINUE TO SLOWLY WEAKEN.

LOW NEAR 10N122W WITH A CENTRAL PRESSURE OF 1007 MB IS MOVING
SLOWLY WEST. CONVECTION HAS BEEN OCCASIONALLY DEVELOPING NEAR
THE LOW. THE LOW IS NEAR THE ITCZ AND THIS IS NOT A FAVORABLE
CONDITION FOR DEVELOPMENT. THE COMPUTER MODELS WEAKEN THE SYSTEM
AS IT SLOWLY MOVES WEST.

ANOTHER LOW NEAR THE ITCZ IS LOCATED NEAR 10N113W WITH A CENTRAL
PRESSURE OF 1007 MB. THIS FEATURE HAS ALSO OCCASIONALLY HAD
CONVECTION DEVELOP NEAR THE CENTER BUT HAS NOT BEEN ORGANIZED BY
THE LOW LEVEL CIRCULATION. THE LOW IS FORECAST TO TRANSITION TO
A TROUGH TODAY AND DRIFT WEST.

REMAINDER OF THE MIDDLE AND UPPER LEVELS IS BROAD ANTICYCLONIC
FLOW.

MODERATE SURFACE RIDGE IS NORTH OF 15N WEST OF 110W. ELSEWHERE
BESIDES THE LOWS MENTIONED ABOVE A BROAD TROUGH IS ANALYZED AT
THE SURFACE.

WINDS IN THE GULF OF TEHUANTEPEC REGION ARE FORECAST TO INCREASE
THIS EVENING AND TONIGHT AND TO REACH GALE FORCE TUESDAY.

$$
LL





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