000
AXPZ20 KNHC 160857
TWDEP 

TROPICAL WEATHER DISCUSSION 
NWS NATIONAL HURRICANE CENTER MIAMI FL 
1005 UTC WED OCT 16 2013

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 
0900 UTC.

...SPECIAL FEATURES...

TROPICAL DEPRESSION PRISCILLA NEAR 17.9N 118.6W AT 16/0900 UTC 
OR 574 NM WSW OF THE SOUTHERN TIP OF BAJA CALIFORNIA MOVING WNW 
AT 6 KT. ESTIMATED MINIMUM CENTRAL PRESSURE 1006 MB. MAXIMUM 
SUSTAINED WIND SPEED IS 30 KT WITH GUSTS TO 40 KT. SEE LATEST 
NHC FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMEP1/   
WTPZ21 KNHC FOR MORE DETAILS. NUMEROUS MODERATE AND ISOLATED 
STRONG CONVECTION IS WITHIN 150 NM IN THE NW QUADRANT. PRISCILLA 
IS FORECAST TO BECOME A REMNANT LOW DURING THE NEXT 24 HOURS AS 
IT MOVES INTO AN AREA OF MORE STABLE AND DRIER AIR...COLDER SEA 
SURFACE TEMPERATURES... AND INCREASING WIND SHEAR ALOFT. THE 
REMNANT CIRCULATION IS THEN FORECAST TO COMPLETELY DISSIPATE BY 
EARLY THIS UPCOMING WEEKEND IF NOT SOONER.

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

THE MONSOON TROUGH EXTENDS FROM 13N86W TO LOW PRES NEAR 
09.5N107W TO 10N120W TO 09N140W. NO ITCZ IS PRESENT E OF 140W. 
NO SIGNIFICANT CONVECTION DIRECTLY RELATED TO THE MONSOON   
TROUGH IS NOTED...HOWEVER SCATTERED MODERATE CONVECTION IS N   
OF 07N E OF 80W...INCLUDING THE GULF OF PANAMA...AND WITHIN 60-
90 NM SW OF CENTRAL AMERICA BETWEEN 85W AND 90W.

...DISCUSSION...

A NORTH TO SOUTH UPPER LEVEL RIDGE EXTENDS ACROSS THE NW   
WATERS FROM NEAR 10N136W TO 32N134W. DRY AND STABLE AIR PREVAILS 
S OF 20N W OF 125W...WITH TROPICAL MOISTURE SPREADING FROM THE 
DEEP TROPICS S OF THE HAWAIIAN ISLANDS TO THE NE AROUND THE 
RIDGE N OF 20N W OF 130W. AN UPPER LEVEL TROUGH IS TO THE E OF 
THE RIDGE FROM SOUTHERN CALIFORNIA SW THROUGH 32N121W TO NEAR 
15N130W. DRY AND STABLE AIR IS PRESENT WITHIN 240 NM EITHER SIDE 
OF THE TROUGH AXIS. 

A LARGE AND EXPANSIVE UPPER LEVEL ANTICYCLONE THAT WAS OVER NE 
MEXICO HAS SHIFTED TO THE E OVER THE GULF OF MEXICO NEAR 22N91W 
WITH A RIDGE REACHING TO THE W-SW THROUGH 23N109W TO 16N120W. 
THIS RIDGE IS SUPPORTING THE REMAINING CONVECTION ASSOCIATED 
WITH PRISCILLA WHILE ALSO SHEARING SAID CONVECTION TO THE W-NW 
AWAY FROM THE CENTER. AN INVERTED UPPER TROUGH REACHES FROM 
22N107W TO 09N111W...SHIFTING W. CONVECTIVE DEBRIS IS SPREADING 
TO THE W-NW FROM 06N TO 22N BETWEEN 100W AND 120W WITH THE ABOVE 
MENTIONED ANTICYCLONE INDUCING EASTERLY FLOW ALOFT ACROSS THE 
WATERS E OF 100W.

ELSEWHERE AT THE SURFACE...A RIDGE OF HIGH PRES STRETCHES FROM 
NEAR 32N136W SE TOWARD THE SOUTHERN BAJA CALIFORNIA PENINSULA 
NEAR 25N112W. WEAK 1008 MB LOW PRES IS EMBEDDED IN THE MONSOON 
TROUGH NEAR 09.5N107W WITH ONLY LIGHT TO MODERATE WINDS...4-6 FT 
SEAS...AND LIMITED CONVECTION IN ITS VICINITY. NO DEVELOPMENT OF 
THIS LOW IS ANTICIPATED DURING THE NEXT 48 HOURS AS IT CONTINUES 
WESTWARD AROUND 5-10 KT.

RELATIVELY BENIGN MARINE CONDITIONS PREVAIL OUTSIDE OF THE 
EFFECTS OF PRISCILLA...WITH LIGHT TO MODERATE WINDS AND 4-7 FT 
SEAS DOMINATING THE DISCUSSION WATERS THROUGHOUT AT LEAST THE 
NEXT 48 HOURS. THE MAIN EXCEPTIONS WILL BY IN THE GULF OF 
CALIFORNIA WHERE WINDS WILL OCCASIONALLY INCREASE TO MODERATE  
TO FRESH LEVELS AS THE PRES GRADIENT OVER THAT REGION 
FLUCTUATES... AND IN THE FAR W CENTRAL WATERS N OF THE MONSOON 
TROUGH/ITCZ WHERE MODERATE TO FRESH WINDS ASSOCIATED WITH    
WEAK SURFACE TROUGHING WILL BE.

$$
LEWITSKY