000
AXPZ20 KNHC 041535
TWDEP 

TROPICAL WEATHER DISCUSSION 
NWS NATIONAL HURRICANE CENTER MIAMI FL
1605 UTC WED JUL 04 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 
1430 UTC.

...SPECIAL FEATURE... 
TROPICAL DEPRESSION FOUR-E CENTERED NEAR 13.1N 107.1W AT 04/1500 
UTC MOVING WNW 13 KT. ESTIMATED MINIMUM CENTRAL PRES IS 1006 MB. 
MAXIMUM SUSTAINED WIND SPEED IS 30 KT GUST TO 40 KT. SEA LATEST 
NHC FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMEP4/WTPZ24 
KNHC FOR MORE DETAILS. SCATTEROMETER DATA SHOWED AN AREA OF 
25-30 KT WINDS TO THE E AND SE OF THE CENTER WITH ISOLATED 35-40 
KT WIND BARBS IN THE AREA OF STRONG CONVECTION. THE DEPRESSION 
IS FORECAST TO REACH TROPICAL STORM STRENGTH NEAR 13.8N 108.4W 
TONIGHT AND LIKELY HURRICANE STATUS BY SAT MORNING. NUMEROUS 
MODERATE SCATTERED STRONG CONVECTION IS NOTED WITHIN 180 NM SW 
SEMICIRCLE DUE TO MODERATE NORTHEASTERLY SHEAR.

...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH...
MONSOON TROUGH AXIS IS FROM 09N85W TO 10N110W THEN RESUMES W OF 
TROPICAL DEPRESSION FOUR-E AT 10N121W TO 07N128W. ITCZ AXIS IS 
FROM 07N128W TO 05N140W. SCATTERED MODERATE TO STRONG CONVECTION 
IS NOTED EITHER SIDE OF THE MONSOON TROUGH FROM 04N TO 10N 
BETWEEN 86W AND 96W. SIMILAR CONVECTION IS ALSO OBSERVED FROM 
10N TO 12N BETWEEN 91W AND 96W.

...DISCUSSION...
TROPICAL DEPRESSION FOUR-E IS MOVING AROUND THE SOUTHERN EDGE OF 
A MID-LEVEL RIDGE OVER NORTHERN MEXICO AND THE CENTRAL UNITED 
STATES. THE RIDGE IS FORECAST TO STRENGTHEN AND BUILD WESTWARD 
DURING THE LATTER PART OF THE WEEK. AS A RESULT...THE CYCLONE IS 
EXPECTED TO TURN WESTWARD IN A COUPLE OF DAYS. ANOTHER 
ANTICYCLONIC CIRCULATION IS NOTED NEAR 14N132W. IN BETWEEN... 
THERE IS A TROUGH EXTENDING FROM 22N118W TO 13N125W. SW TO W 
UPPER-LEVEL FLOW DOMINATES ROUGHLY THE AREA N OF 20N W OF 120W. 
STRONG SUBSIDENCE AND THE IMPLIED DRY AIR MASS COVERS THE AREA 
NW OF LINE FROM 20N110W TO 10N140W. 

A RIDGE DOMINATES THE NW CORNER OF THE FORECAST REGION. THE MOST 
RECENT SCATTEROMETER PASS SHOWS AN AREA OF 20 KT NE WINDS ON THE 
SOUTHERN PERIPHERY OF THE RIDGE FROM 19N TO 23N W OF 134W. 
TRADES ARE EXPECTED TO PERSIST OVER THE NEXT COUPLE OF DAYS IN A 
RELATIVE SMALL AREA FROM 11N-13N TO 18N W OF 137W WITH SEAS TO 8 
FT.

A SURFACE TROUGH EXTENDS FROM 16N116W TO 10N121W. SCATTERED 
MODERATE CONVECTION CAN BE FOUND WITHIN 90 NM EITHER SIDE OF THE 
TROUGH AXIS.

THE MONSOON TROUGH IS VERY ACTIVE E OF 100W. A LARGE AREA OF 
DISTURBED WEATHER IS EMBEDDED IN THE TROUGH W OF COSTA RICA AND 
EXTENDS WESTWARD OVER THE PACIFIC OCEAN FOR SEVERAL HUNDRED 
MILES AS PREVIOUSLY DESCRIBED. ENVIRONMENTAL CONDITIONS ARE 
EXPECTED TO BE CONDUCIVE FOR GRADUAL DEVELOPMENT OF THIS 
DISTURBANCE OVER THE NEXT FEW DAYS. CURRENTLY...THIS SYSTEM HAS 
A LOW CHANCE OF BECOMING A TROPICAL CYCLONE DURING THE NEXT 48 
HOURS AS IT MOVES WESTWARD AT ABOUT 10 MPH.

ELY WINDS OF 20 KT WITH SEAS TO 8 FT CONTINUE ACROSS THE GULF OF 
PAPAGAYO AND ARE FORECAST TO INCREASE TO 20-25 KT BY FRI MORNING 
WITH SEAS TO 9 FT.

$$
GR