Eastern Pacific Tropical Weather Discussion

000
AXPZ20 KNHC 182148
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
2205 UTC FRI APR 18 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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
2345 UTC. 

...SPECIAL FEATURE...

GALE WARNING FOR THE GULF OF TEHUANTEPEC... 

A SURFACE LOW OVER THE NE GULF OF MEXICO WILL DRAG THE SOUTHERN 
END OF A COLD FRONT E THROUGH THE S-CENTRAL GULF OF MEXICO 
TONIGHT. NORTHERLY FLOW WILL INCREASE ACROSS THE WESTERN GULF OF 
MEXICO IN THE WAKE OF THIS FRONT WITH NORTHERLY 20-25 KT WINDS 
SURGING INTO THE GULF OF TEHUANTEPEC THIS EVENING. THE GRADIENT 
WILL TIGHTEN FURTHER WITH MINIMAL GALE CONDITIONS EXPECTED BY 
MIDNIGHT TONIGHT WITH THESE MINIMAL GALE CONDITIONS CONTINUING 
THROUGH SUNRISE ON SAT. WINDS WILL QUICKLY DIMINISH THROUGHOUT 
THE DAY ON SAT WITH ONLY N-NE 20-25 KT WINDS EXPECTED ON SAT 
EVENING THROUGH SUNRISE ON SUN. THE NOCTURNAL MAXIMUM DRAINAGE 
SHOULD ONLY MAX 15-20 KT EACH NIGHT FROM SUN NIGHT THROUGH WED 
NIGHT. 

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

THE EPAC MONSOON TROUGH EXTENDS SW FROM THE COAST OF PANAMA AT 
08N82W TO 06N90W WHERE SCATTEROMETER WINDS INDICATE A TRANSITION 
TO AN ITCZ AXIS...WHICH CONTINUES W TO 07N97W...THEN DIPS SW TO 
05N111W...THEN WIGGLES WESTWARD TO BEYOND 06N140W.

SCATTERED MODERATE ISOLATED STRONG CONVECTION IS DECAYING ALONG
THE COLOMBIAN COAST WITHIN 75 NM OF 05.5N78W. SIMILAR 
CONVECTION IS NOTED ALONG THE MONSOON TROUGH AND ITCZ AXIS 
WITHIN 150 NM EITHER SIDE OF A LINE FROM 07.5N84W TO 03N107W AND
WITHIN 120 NM EITHER SIDE OF A LINE FROM 08N120W TO 04.5N132W. 
ISOLATED MODERATE TO STRONG CONVECTION IS ALSO NOTED ALONG THE 
WESTERN PORTION OF THE ITCZ WITHIN THE AREA BOUNDED BY 02-77N 
BETWEEN 135-140W. 

A PERSISTENT MID-UPPER TROUGH NOW HAS A SURFACE REFLECTION 
EXTENDING FROM 14N107W TO 02N111W. ISOLATED MODERATE TO STRONG 
CONVECTION IS FLARING WITHIN 90 NM EITHER SIDE OF A LINE FROM 
13N108W TO 03N110W TO 04N117W.

...DISCUSSION...                                                

AN UPPER CYCLONE HAS MOVED EASTWARD ACROSS THE NORTHERN PORTION 
OF THE DISCUSSION AREA OVER THE PAST FEW DAYS AND IS NOW MOVING 
E ACROSS THE NORTHERN BAJA CALIFORNIA PENINSULA. A MID TO UPPER 
TROUGH EXTENDING TO THE SW HAS AMPLIFIED TO A BASE NEAR 
17N127W. DENSE UPPER DEBRIS MOISTURE THAT ORIGINATED IN THE 
CENTRAL PACIFIC IS NOW CONCENTRATED TO THE E OF THE TROUGH AXIS 
AND SPREADING E ACROSS NORTHERN MEXICO WITH SIGNIFICANT MOISTURE 
ALSO SPREADING N ACROSS SOUTHERN CALIFORNIA...ARIZONA...NEW 
MEXICO AND EXTREME W TEXAS. SOME OF THIS MOISTURE WILL SPREAD E 
ACROSS THE WESTERN GULF OF MEXICO TONIGHT.         

AN UPPER LEVEL ANTICYCLONE IS CENTERED JUST W OF THE AREA AT 
08N141W WITH A RIDGE EXTENDING E ACROSS THE TROPICS TO A CREST
NEAR 06N113W. UPPER DIFFLUENCE UNDER THIS RIDGE HAS ENHANCED THE 
INCREASE IN CONVECTION ALONG THE ITCZ TO THE W OF 115W. THE 
PREVIOUSLY DESCRIBED SURFACE TROUGH FROM 14N107W TO 02N111W IS 
UNDER AN UPPER TROUGH THAT IS QUASI-STATIONARY FROM 04-15N 
BETWEEN 100-112W. THIS UPPER TROUGH SEPARATES THE ANTICYCLONIC 
FLOW JUST DESCRIBED OVER THE WESTERN PORTION FROM ANOTHER 
TROPICAL ANTICYCLONE OVER THE SE PORTION ASSOCIATED WITH AN 
UPPER RIDGE EXTENDING W OFF THE COAST OF COLOMBIA ALONG 07N TO 
THE E OF 100W. THIS UPPER RIDGE IS IN PHASE WITH THE LOWER LEVER 
MONSOON TROUGH AND ITCZ...AND IS SUPPORTING THE INCREASE IN 
CONVECTION. SOME OF THE RESULTANT DEBRIS MOISTURE IS ADVECTED NE 
ACROSS CENTRAL AMERICA...THEN TURNS E-NE ACROSS THE CENTRAL 
CARIBBEAN.

A SURFACE HIGH PRESSURE RIDGE EXTENDS FROM 29N140W TO NEAR 
18N105W. NE TRADES ARE ENHANCED TO 15-20 KT BETWEEN THE RIDGE 
AND 07N TO THE W OF 122W...WITH SEAS OF 6-8 FT IN MIXED LONG 
PERIOD NW AND NE SWELL WITH ADDITIONAL LONG PERIOD CROSS-
EQUATORIAL SE SWELL. THIS AFFECTED AREA S OF THE RIDGE WILL 
PERSIST THROUGH THE WEEKEND. NW TO N 15 KT WINDS TO THE NE OF 
THE RIDGE WILL CONTINUE TO THE PACIFIC COAST OF THE BAJA 
CALIFORNIA PENINSULA WITH SEAS OF 4-5 FT. A NEW BATCH OF NW 
SWELL WILL ARRIVE AT 30N140W SAT NIGHT...AND CONTINUE TO 
PROPAGATE E REACHING THE NW COAST OF THE BAJA PENINSULA IN THE 
FORM COMBINED SEAS OF 6-9 FT ON MON. SEAS OF 8-9 FT IS EXPECTED 
ACROSS THE DISCUSSION WATERS N OF 20N BETWEEN 112W-135W ON TUE.

$$
NELSON