000
AXPZ20 KNHC 140959
TWDEP 

TROPICAL WEATHER DISCUSSION 
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
1005 UTC TUE OCT 13 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 
0845 UTC.

...SPECIAL FEATURE... 

AT 0900 UTC PATRICIA WAS DOWNGRADED TO A TROPICAL DEPRESSION... 
LOCATED NEAR 22.8N 109.7W OR ABOUT 15 NM S OF THE SOUTHERN TIP 
OF BAJA CALIFORNIA...MOVING WNW OR 300 DEG AT 5 KT. MAXIMUM 
SUSTAINED WINDS WERE 25 KT GUSTS TO 35 KT. ESTIMATED MINIMUM 
CENTRAL PRESSURE WAS 1006 MB. A VERY SMALL AND ISOLATED AREA OF 
WEAK TO MODERATE CONVECTION HAS FLARED ON AND OFF DURING THE 
PAST FEW HOURS. AN OVERNIGHT QUIKSCAT PASS SHOWED 25 TO 30 KT 
WINDS WITHIN 45 NM OF THE CENTER OF PATRICIA IN ALL BUT THE NE 
QUADRANTS. THE REMNANTS OF PATRICIA ARE EXPECTED TO CONTINUE TO 
GRADUALLY WEAKEN...AND BECOME A REMNANT LOW WITHIN 12 HOURS... 
AND DISSIPATED WITHIN 48 HOURS WHILE IT MOVES WESTWARD. SEE THE 
LAT NHC FORECAST ADVISORY UNDER AWIPS/WMO HEADERS 
MIATCMEP4/WTPZ24 KNHC FOR MORE DETAILS.

...TROPICAL WAVES...

A TROPICAL WAVE WAS ANALYZED ALONG 95W MOVING WEST 15 KT. A 1009 
MB SURFACE LOW PREVIOUSLY ATTRIBUTED TO THIS WAVE WAS ANALYZED 
NEAR 07.5N90W. THIS LOW WAS MOVING SLOWLY WEST AROUND 5 KT. 
SATELLITE IMAGERY AND AN OVERNIGHT QUIKSCAT PASS INDICATE A 
BROAD AND ELONGATED CYCLONIC CIRCULATION ACROSS THE AREA THAT 
WAS DEVELOPING PRIOR TO THE ARRIVAL OF THE WAVE. SCATTERED 
MODERATE CONVECTION OCCURRING BETWEEN 95W AND THE COAST OF COSTA 
RICA IS SHOWING SIGNS OF ROTATING NW ALONG THIS ELONGATED TROUGH 
AXIS. SATELLITE IMAGERY SUGGESTS MORE THAN ONE MID LEVEL 
CYCLONIC CIRCULATION WITHIN THIS BROAD CIRCULATION. GLOBAL 
MODELS CONTINUE TO FORECAST THIS GYRE TO SHIFT WNW WITH A LOW 
GRADUALLY BECOMING BETTER ORGANIZED WITHIN 3 DAYS...AND THIS 
SYSTEM DOES SHOW POTENTIAL TO EVENTUALLY DEVELOP INTO A TROPICAL 
CYCLONE IN A FEW DAYS. 

...ITCZ...

THE INTERTROPICAL CONVERGENCE ZONE WAS ALONG 07N79W TO 09N82W TO 
08.5N89W TO 07N98W TO 08N103W TO 13N110W TO 12N120W TO 14N135W. 
SCATTERED MODERATE CONVECTION WAS FROM 06N TO 12N E OF 95W. 
ISOLATED TO SCATTERED MODERATE CONVECTION WAS WITHIN 180 NM OF 
AXIS BETWEEN 101W AND 110W. SCATTERED MODERATE CONVECTION WAS 
WITHIN 90 NM S AND 180 NM S OF AXIS W OF 114W.

...DISCUSSION...

A LARGE DEEP LAYERED LOW PRESSURE SYSTEM WAS ALONG THE PACIFIC 
NW COAST OF N AMERICA...YIELDING A STRONG SW TO W JET MOVING 
INTO CENTRAL AND SRN CALIFORNIA AND JUST N OF THE AREA. S OF 
THIS...AN ELONGATED RIDGE EXTENDED FROM THE ACTIVE ITCZ S OF THE 
HAWAIIAN ISLANDS NE THROUGH 16N126W TO THE GULF OF MEXICO. A 
WEAKENING MID TO UPPER TROUGH EXTENDED FROM 30N102W TO 
22N117W...JUST TO THE NW OF TROPICAL DEPRESSION PATRICIA. THE 
CONTINENTAL PORTION OF THIS TROUGH IS PULLING AWAY FROM PATRICIA 
AND WILL MOVE NE OF THE AREA THIS MORNING. STEERING FLOW FOR 
PATRICIA WILL BE DOMINATED BY THE RIDGE TO ITS NW THE REMAINDER 
OF THE PERIOD. A 1018 MB HIGH PRES CURRENTLY LIES NEAR 26N121W 
WILL MIGRATE N-NW OVER THE PERIOD AND STRENGTHEN AS THE DEEP 
LAYER TROUGH OVER THE EASTERN PACIFIC PRIMARILY N OF FORECAST 
WATERS PASSES INTO THE WESTERN U.S. ALLOWING DEEP LAYER RIDGING 
TO BUILD ACROSS N WATERS. THE PRES GRADIENT ALONG THE COAST OF 
THE BAJA PENINSULA WILL BUILD BETWEEN THIS RIDGE AND PATRICIA 
ALLOWING FOR WINDS TO PERSIST AROUND 20 KT THROUGH 48 HOUR WHILE 
GRADUALLY SHIFTING N. THE TROUGHING WELL NORTH OF THE AREA IS 
BRINGING NW SWELL INTO THE REGION...WITH SEAS EXPECTED TO REACH 
15-16 FT OVER N WATERS WED. AS THE RIDGING BUILDS W OVER THE 
NEXT FEW DAYS...EXPECT EASTERLY FLOW TO INCREASE W OF 125W 
PRIMARILY FROM 13N TO 20N BETWEEN THE RIDGE AXIS AND THE 
ENHANCED TROUGHING OVER W WATERS EMBEDDED IN THE ITCZ.

TRADE WIND FLOW ACROSS THE SW CARIBBEAN HAS BEGUN TO DIMINISH 
AND WINDS IN THE GULF OF PAPAGAYO HAVE DROPPED BELOW 20 KT 
OVERNIGHT. FURTHER SOUTH...INCREASED SW FLOW OF 20-25 KT S OF 
THE ITCZ IS AIDING IN PERSISTENT CONVECTION AND THE MAINTENANCE 
OF A CYCLONIC GYRE ACROSS THE FAR EPAC. GLOBAL MODELS SHOW SLOW 
AND GRADUAL DEVELOPMENT AND IMPROVED ORGANIZATION OF THE 1009 MB 
SURFACE LOW AS IT MOVES WNW ACROSS THIS REGION OVER THE NEXT 
SEVERAL DAYS. 

$$
STRIPLING