East Pacific Tropical Weather Discussion

000
AXPZ20 KNHC 061616
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
1605 UTC SAT OCT 06 2012

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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
1500 UTC.

...SPECIAL FEATURE...

THE EMBEDDED SURFACE LOW PRESSURE ALONG THE MONSOON TROUGH NEAR 
14N118.7W HAS RECENTLY BEEN UPGRADED TO TROPICAL DEPRESSION 
FIFTEEN-E. THIS NEWLY CLASSIFIED T.D. HAS MAXIMUM SUSTAINED WINDS
30 KT GUSTS 40 KT AND WAS MOVING W OR 280 DEG AT 9 KT. ESTIMATED 
CENTRAL MINIMUM PRESSURE IS 1006 MB. CONVECTION ASSOCIATED WITH 
THIS LOW HAS BEEN IMPROVING OVERNIGHT...WITH A LARGE CLUSTER 
ACROSS THE NW SEMICIRCLE OF THE LOW BECOMING MORE OF A CURVED 
BAND THIS MORNING...WITH DEFINITIVE MID LEVEL CYCLONIC TURNING 
OVER OR JUST TO THE W OF THE SURFACE CENTER. A 0452 UTC ASCAT 
PASS LAST NIGHT SHOWED AN ELONGATED NE TO SW ALIGNED TROUGH... 
INDICATING THE POSITION OF THE MONSOON TROUGH...WITH SHARP 
CYCLONIC TURNING NEAR 13.8N116W...BUT DID NOT SUGGEST A CLOSED 
CIRCULATION. THE CONVECTIVE BANDING HAS IMPROVED CONSIDERABLY 
SINCE THAT TIME...AND A TROPICAL DEPRESSION HAS FORMED THIS 
MORNING. SCATTERED TO NUMEROUS MODERATE TO STRONG CONVECTION WAS 
OCCURRING WITHIN 270 NM NE AND 180 NM SW SEMICIRCLES...WHILE  
SCATTERED MODERATE ISOLATED STRONG CONVECTION WAS ELSEWHERE 
WITHIN 360 NM SW QUADRANT. THE T.D. REMAINS UNDERNEATH AN UPPER 
LEVEL RIDGE...SANDWICHED BETWEEN TWO UPPER LEVEL HIGHS...AND IS 
IN A MARGINALLY FAVORABLE UPPER LEVEL ENVIRONMENT. COMPUTER 
MODEL GUIDANCE SUGGESTS THAT THE T.D. WILL MOVE WNW TO NW DURING 
THE NEXT COUPLE OF DAYS...AND HAS ONLY 36-48 HOURS FOR IMPROVED 
ORGANIZATION AND STRENGTHENING BEFORE REACHING COOLER SST'S AND 
MORE STABLE UPPER LEVEL CONDITIONS. THE T.D. IS FORECAST TO 
STRENGTHEN TO A TROPICAL STORM WITHIN 24 HOURS.

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

MONSOON TROUGH EXTENDS FROM 10N75W TO 08.5N97W TO 10N107W WHERE 
IT FRACTURES...THEN RESUMES FROM 17N111W THROUGH THE T.D. 
FIFTEEN-E AT 14N118.7W THROUGH LOW PRES NEAR 08.5N124W 1008 MB 
TO 08N128W...WHERE IT TRANSITIONS TO ITCZ...CONTINUING ON TO 
09.5N134W TO BEYOND 07N140W. SCATTERED MODERATE ISOLATED STRONG 
CONVECTION NOTED WITHIN 180 NM S OF THE TROUGH E OF 107W.

...DISCUSSION...

AS MENTIONED ABOVE...TWO UPPER LEVEL ANTICYCLONES STRADDLE THE 
NEW T.D....AND FORM AN UPPER LEVEL RIDGE N OF 10N EXTENDING 
BETWEEN 104W AND 132W. T.D. FIFTEEN-E HAS FORMED FROM A DEEP 
LAYERED EASTERLY WAVE...AND MIDDLE LEVEL CYCLONIC TURNING CAN 
STILL BE SEEN SURROUNDING THE T.D. IN WATER VAPOR IMAGERY. BROAD 
UPPER BLOCKING PATTERN PERSISTS ACROSS THE REGION THIS 
MORNING...WITH LITTLE CHANGES EXPECTED UNTIL THE RIDGE BEGINS TO 
FLATTEN MONDAY THROUGH TUESDAY. 

ELSEWHERE AT THE LOW LEVELS...BROAD BUT WEAK SURFACE RIDGING 
COVERS THE DISCUSSION AREA N OF 18N W OF 118W WITH AN ASSOCIATED 
1018 MB HIGH CENTER AT 29N128W. SOUTHWESTERLY LOW LEVEL 
MONSOONAL WINDS AT 15-20 KT...ALONG WITH CROSS EQUATORIAL S 
SWELL...CONTINUES TO RESULT IN AN AREA OF SEAS 6-8 FT IN THE 
AREA BOUNDED FROM 08N TO 10N BETWEEN 114W-120W. WINDS WILL 
DIMINISH TO 15 KT AND SEAS WILL SUBSIDE TO 4-7 FT ON SUN.

NW WINDS OCCURRING E OF THE SURFACE RIDGE WILL INCREASE TO 
20-25 KT OVER THE AREA N OF 28N E OF 118W TO THE NORTHERN 
PORTION OF THE BAJA CALIFORNIA PENINSULA THIS AFTERNOON...AS THE 
MODERATE GRADIENT TIGHTENS...AND PERSIST THROUGH EARLY TUE. THIS 
GRADIENT IS THEN FORECAST TO RELAX AFTER TUE. LONG PERIOD 
SOUTHERN HEMISPHERIC S TO SW SWELLS ARE FORECAST BY WAVE MODEL 
GUIDANCE TO SPREAD ACROSS THE ENTIRE AREA E OF 120W INTO EARLY 
NEXT WEEK. THESE SWELLS ARE EXPECTED TO CULMINATE IN 4-5 FT SEAS 
ALONG MUCH OF THE COAST OF MEXICO INCLUDING THE SOUTHERN PORTION 
OF THE BAJA CALIFORNIA PENINSULA...AND THE SOUTHERN TIER OF THE 
GULF OF MEXICO.

GAP WINDS...NW TO N WINDS OF 20-25 KT WERE DEPICTED OVERNIGHT BY 
A 0308 UTC ASCAT PASS THROUGH THE GULF OF TEHUANTEPEC AND 
DOWNSTREAM TO THE S FOR SOME 120 NM. THESE WINDS AREA EXPECTED 
TO BRIEFLY DIMINISH THIS AFTERNOON....THEN INCREASE AGAIN TO 
20-25 KT STARTING LATE TONIGHT AND LAST THROUGH EARLY THIS WEEK 
AS HIGH PRES RIDGES SWD ACROSS CENTRAL AND SOUTHEASTERN MEXICO.

$$
STRIPLING