000
AXPZ20 KNHC 240949
TWDEP 

TROPICAL WEATHER DISCUSSION                                      
NWS NATIONAL HURRICANE CENTER MIAMI FL                         
1005 UTC WED SEP 24 2014

TROPICAL WEATHER DISCUSSION FOR THE EASTERN PACIFIC OCEAN FROM 
THE EQUATOR TO 32N...EAST OF 140W. THE FOLLOWING INFORMATION IS 
BASED ON SATELLITE IMAGERY...WEATHER OBSERVATIONS...RADAR...AND 
METEOROLOGICAL ANALYSIS.

BASED ON 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
0945 UTC.

...SPECIAL FEATURES...
 
A 1007 MB SURFACE LOW PRESSURE IS EMBEDDED IN THE MONSOON TROUGH 
NEAR 15N103W...AND IS MOVING W-NW AT 10 KT. AN UPPER LEVEL 
ANTICYCLONE IS CENTERED NEAR THE PACIFIC COAST OF THE BAJA 
CALIFORNIA PENINSULA AT 28N115W...WITH ITS ANTICYCLONIC ENVELOPE 
COVERING THE DISCUSSION AREA N OF 10N BETWEEN 99-122W. 
ASSOCIATED NE WIND SHEAR IS EXPOSING THE LOW LEVEL CENTER WITH 
SCATTERED MODERATE ISOLATED STRONG CONVECTION CURRENTLY OBSERVED 
WITHIN 240 NM OVER THE SW QUADRANT OF CENTER. ENVIRONMENTAL 
CONDITIONS ARE EXPECTED TO BECOME MORE FAVORABLE FOR THIS 
SURFACE LOW TO STRENGTHEN IN THE NEXT FEW DAYS...WITH A HIGH 
POSSIBILITY OF TROPICAL CYCLONE FORMATION. THE FORECAST 
POSITIONS FROM THE OFFICIAL MARINE GRIDS LOW ARE NEAR 14N106W 
1006 MB LATE TONIGHT...AND NEAR 16N109W 1004 MB LATE THU 
NIGHT...NEAR 17N111W LATE FRI NIGHT...NEAR 19N114W LATE SAT 
NIGHT...NEAR 22N117W LATE SUN NIGHT. THESE POSITIONS ARE LIKELY 
TO CHANGE AS MODEL GUIDANCE UPDATES. 

...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH...

THE MONSOON TROUGH EXTENDS W ACROSS NORTHERN PANAMA TO THE  
PACIFIC COAST OF COSTA AT 09N83W...THEN CONTINUES NW PARALLELING 
THE COAST TO 16N97W...THEN TURNS SW THROUGH AN EMBEDDED LOW 
PRESSURE AT 15N103W...THEN CONTINUES W TO 14N111W...THEN SW TO 
07N122W WHERE SCATTEROMETER WINDS INDICATE A TRANSITION TO AN 
ITCZ...WHICH CONTINUES W TO 06N131W THEN NW TO BEYOND 08N140W. 

SCATTERED MODERATE ISOLATED STRONG CONVECTION IS OBSERVED ALONG 
THE MONSOON TROUGH WITHIN 150 NM OF THE COAST OF CENTRAL AMERICA 
AND MEXICO FROM 86-96W...AND ALSO MOVED OFF THE MEXICAN COAST 
WITHIN 90 NM EITHER SIDE OF A LINE FROM 23N105W TO 18N108W. 
ISOLATED MODERATE TO STRONG CONVECTION IS NOTED WITHIN 45 NM 
EITHER SIDE OF A LINE OF FROM 04N77W TO 07N88W TO 11N95W.

...DISCUSSION...   

THE REMNANTS OF FORMER TROPICAL CYCLONE POLO ARE ANALYZED AS A 
1008 MB LOW PRESSURE NEAR 25N116W. WINDS HAVE DIMINISHED TO 10-
15 KT WITHIN ABOUT 120 NM W OF THE CENTER...WITH SEAS OF 5-7 FT. 
THE LOW IS FORECAST TO MOVE SW AND WEAKEN TO A OPEN TROUGH FROM 
16N116W TO 20N118W ON THU.  

A WEAK COLD FRONT EXTENDS FROM 32N130W TO 26N140W ACCOMPANIED BY 
ONLY A SW-W-NW 10-15 KT WIND SHIFT. NW SWELLS ARE MIXING WITH 
LONG PERIOD SE SWELL ACROSS THE DISCUSSION WATERS NW OF THE 
FRONT...RESULTING IN COMBINED SEAS OF 7-11 FT. THE FRONT IS 
EXPECTED TO WASH OUT FROM 32N120W TO 23N134W LATE THU...BUT 
BUILDING HIGH PRESSURE IN ITS WAKE WILL INCREASE THE NORTHERLY 
FLOW TO 15-20 KT ALONG THE PACIFIC COAST OF THE BAJA PENINSULA 
TO THE N OF 30N LATE THU...WITH THESE CONDITIONS SPREADING AS 
FAR S AS 27N ON FRI AFTERNOON...WITH THE GRADIENT BEGINNING TO 
RELAX FRI NIGHT. SEAS WILL BUILD TO 7-10 FT IN MIXING LONG 
PERIOD NW AND SE SWELL ACROSS THE DISCUSSION WATERS NW OF A LINE 
FROM 29N115W TO 16N140W THU NIGHT...THEN GRADUALLY SUBSIDE OVER 
THE WEEKEND.      

$$
NELSON