000
AXPZ20 KNHC 241516
TWDEP 

TROPICAL WEATHER DISCUSSION 
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
1605 UTC SAT OCT 24 2009

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 
1415 UTC.


...ITCZ...
THE INTERTROPICAL CONVERGENCE ZONE AXIS EXTENDS FROM 09N86W TO 
08N93W TO 11N113W TO 09N125W TO 10N137W. SCATTERED MODERATE 
CONVECTION LIES WITHIN 1120 NM S OF THE ITCZ AXIS BETWEEN 96W 
AND 99W AND WITHIN 120 NM EITHER SIDE OF THE ITCZ AXIS BETWEEN 
117W AND 133W.

...DISCUSSION...
A LONGWAVE MID TO UPPER LEVEL TROUGH FROM SOUTH TEXAS NEAR 
27N99W THROUGH MEXICO TO 18N110W TO 13N125W WILL REMAIN 
STATIONARY THROUGH THE WEEKEND BEFORE BEING RELOADED BY 
SHORTWAVE ENERGY CURRENTLY PASSING OVER THE NE PACIFIC RIDGE AND 
EXPECTED TO MAKE ITS WAY INTO THE BACKSIDE OF THIS LONGWAVE 
TROUGH LATE SUN OVER THE U.S. WESTERN STATES. THE COLD FRONT AT 
THE SURFACE ASSOCIATED WITH THIS TROUGH LIES OVER THE GULF OF 
MEXICO AND EXTENDS SOUTH INTO THE BAY OF CAMPECHE. ACCORDING TO 
THE 0314 UTC ASCAT PASS...20 KT NW TO N WINDS ARE FUNNELING 
THROUGH THE ISTHMUS OF TEHUANTEPEC INTO THE PACIFIC WITHIN 60 NM 
OF THE GULF OF TEHUANTEPEC. THESE WINDS ARE EXPECTED TO DIMINISH 
AROUND SUNRISE TOMORROW. SW FLOW ON THE EASTERN EDGE OF THE MID 
TO UPPER LEVEL TROUGH AXIS IS TRANSPORTING TROPICAL MOISTURE NE 
INTO MEXICO WITH A LINE OF CIRRUS EVIDENT ON SATELLITE IMAGERY 
WITHIN 150 NM OF LINE FROM 11N113W TO 23N100W. A 1009 MB SURFACE 
LOW LIES NEAR 11N113W...IN THE VICINITY OF THE REAR RIGHT 
QUADRANT ON THE UPPER JET.  DESPITE MODERATE UPPER LEVEL 
DIFFLUENCE NEAR THE LOW...CONVECTION IS NOT WELL ORGANIZED WITH 
ONLY ISOLATED MODERATE CONVECTION FOUND WITHIN 150 NM E AND 180 
NM W QUADRANTS.

RELATIVELY STRONG RIDGING IS IN PLACE IN THE MID TO LOW LEVELS 
OVER N WATERS. NORTHERLY FLOW BETWEEN THE EASTERN EDGE OF THE 
RIDGE AND ENHANCED TROUGHING OVER THE SOUTHERN U.S. PLAINS AND 
NORTHERN MEXICO IS IN THE 20 TO 25 KT RANGE ACCORDING TO THE 
0500 AND 0640 UTC ASCAT PASSES. NE TRADE WINDS ON THE SOUTH SIDE 
OF THE RIDGE AXIS ARE ALSO IN THE 20 TO 25 KT RANGE ACCORDING TO 
THE 0636 UTC ASCAT AND 0354 QUIKSCAT PASSES. NW SWELL 
ORIGINATING OUT OF FORECAST WATERS IS RAISING SIGNIFICANT WAVE 
HEIGHTS TO 8 TO 10 FT N OF 18N AND W OF 115W AND TO THE E OF THE 
AREA OF WINDS OVER 20 KT. THIS SWELL WILL SUBSIDE AS IT TRAVELS 
SE OVER THE NEXT DAY OR TWO. HOWEVER...THE RIDGE AND WINDS WILL 
REMAIN IN PLACE AND RELATIVELY UNCHANGED OVER THE NEXT TWO DAYS. 

CLOSER TO THE COAST...SCATTERED MODERATE CONVECTION CAN BE FOUND 
WITHIN 90 NM OF LOW PRES NEAR 09N86W...EXCEPT WITHIN 210 NM SE 
QUADRANT WHERE THE CONVECTION EXTENDS E OVER COSTA RICA. THIS 
SYSTEM LIES IN A REGION OF STRONG UPPER LEVEL DIFFLUENCE BETWEEN 
THE UPPER RIDGE AXIS EXTENDING FROM AN ANTICYCLONE NEAR 06N97W 
TO 04N82W AND A CARIBBEAN UPPER LOW NEAR 19N79W. THIS AREA OF 
DIFFLUENCE SHOULD SHIFT W WITH THE SURFACE LOW OVER THE NEXT FEW 
DAYS. THE 0312 UTC ASCAT PASS SHOWS S TO SW WINDS TO 20 KT 
FEEDING INTO THE LOW AND EXTENDING W TO NEAR 118W. THESE WINDS 
ARE EXPECTED TO SHIFT W WITH THE LOW AS A WELL.

$$
SCHAUER