000
AXPZ20 KNHC 172148
TWDEP
TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
2205 UTC THU APR 17 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
2145 UTC.
...SPECIAL FEATURE...
GALE WARNING FOR THE GULF OF TEHUANTEPEC...N-NE SWELL FROM
YESTERDAYS STORM/GALE EVENT IN THE GULF OF TEHUANTEPEC WILL
CONTINUE TO PROPAGATE SW MIXING WITH LONG-PERIOD CROSS
EQUATORIAL S SWELL. SEAS WILL FINALLY SUBSIDE BELOW 8 FT NEAR
07N104W LATE TONIGHT. A SURFACE LOW WILL FORM ALONG A NORTHWARD
DRIFTING WARM FRONT OVER THE NE GULF OF MEXICO EARLY TONIGHT. AS
THE LOW LIFTS OUT TO THE NE IT WILL MOVE THE SOUTHERN END OF THE
FRONT E AGAIN AS A COLD FRONT WITH NORTHERLY FLOW INCREASING
ACROSS THE WESTERN GULF OF MEXICO. NORTHERLY FLOW WILL INCREASE
TO 20-25 KT IN THE GULF OF MEXICO ON FRI EVENING WITH A MINIMAL
GALE CONDITIONS EXPECTED BY MIDNIGHT AND CONTINUING THROUGH
SUNRISE ON SAT...THEN QUICKLY DIMINISHING THROUGHOUT THE DAY ON
SAT WITH ONLY 15-20 KT N WINDS EXPECTED ON SAT EVENING. THE
NORTHERLY DRAINAGE FLOW WILL INCREASE AGAIN TO 20-25 KT LATE SAT
NIGHT THROUGH SUNRISE ON SUN. THE NOCTURNAL MAXIMUM SHOULD ONLY
NE 15-20 KT EACH NIGHT FROM SUN NIGHT THROUGH THU NIGHT.
...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH...
THE EPAC MONSOON TROUGH EXTENDS SW FROM THE COAST OF COSTA RICA
AT 10N85W TO 06N90W WHERE SCATTEROMETER WINDS INDICATE A
TRANSITION TO AN ITCZ AXIS...WHICH CONTINUES WSW TO 05N101W TO
05N114W TO BEYOND 03N140W.
SCATTERED MODERATE ISOLATED STRONG CONVECTION IS NOTED ALONG
THE MONSOON TROUGH AND THE EASTERN SEGMENT OF THE ITCZ WITHIN
60 NM EITHER SIDE OF LINES FROM 05.5N82W TO 04.5N99W AND
FROM 10N91W TO 05.5N95W. SIMILAR CONVECTION IS NOTED OVER AND
TO THE N OF THE ITCZ WITHIN 60 NM EITHER SIDE OF A LINE FROM
08N103W TO 04N108W AND WITHIN 180 NM EITHER SIDE OF A LINE
FROM 04N122W TO 06N140W.
...DISCUSSION...
AN UPPER CYCLONE IS OVER THE NORTHERN PORTION OF THE DISCUSSION
AREA AT 31N125W WITH AN UPPER TROUGH EXTENDING SW TO BEYOND
25N140W AND ACCOMPANIED BY DRY UPPER AIR. A SHORTWAVE TROUGH IS
SWINGING E ACROSS THE CENTRAL CONUS WITH THE TROUGH AXIS
EXTENDING S ACROSS CENTRAL OF MEXICO TO A BASE AT 22N103W. A
BAND OF VERY DRY UPPER AIR FOLLOW THE TROUGH AXIS ACROSS NW OLD
MEXICO.
AN UPPER LEVEL ANTICYCLONE IS CENTERED AT 08N129W WITH AN UPPER
RIDGE EXTENDING N-NE BETWEEN THE TWO UPPER TROUGHS TO A SHARP
CREST OVER THE NORTHERN GULF OF CALIFORNIA. AN UPPER RIDGE ALSO
EXTENDS W FROM THE ANTICYCLONE ACROSS THE DEEP TROPICS TO BEYOND
13N140W WITH UPPER DIFFLUENCE S OF THIS RIDGE ENHANCING THE
CONVECTION ALONG THE WESTERN SEGMENT OF THE ITCZ AS PREVIOUSLY
DESCRIBED. A RIDGE ALSO EXTENDS E-NE FROM THE ANTICYCLONE TO A
FAIRLY SHARP CREST AT 14N109W. DRY UPPER AIR WITHIN THE
ANTICYCLONIC ENVELOPE IS SUPPRESSING CONVECTION ACROSS THE
TROPICS FROM 06-17N BETWEEN 107-127W...EXCEPT FOR A THIN LINE OF
MODERATE CONVECTION FROM 02N116W TO 03N120W. DENSE UPPER
MOISTURE IS ADVECTED E ALONG THE N PERIPHERY OF THIS UPPER
ANTICYCLONE...WITHIN 180 NM EITHER SIDE OF A LINE FROM 16N140W
TO 25N116W TO OVER THE GULF OF MEXICO AT 24N96W WHERE THE
MOISTURE TURNS NE AHEAD OF THE SHORTWAVE OVER THE CENTRAL CONUS.
AN UPPER TROUGH IS DISSIPATING OVER THE TROPICAL PACIFIC FROM
16N95W TO 03N113W. THIS TROUGH SEPARATES THE BROAD ANTICYCLONIC
FLOW ALREADY MENTIONED OVER THE NW PORTION FROM ANTICYCLONIC
FLOW OVER THE DISCUSSION AREA TO THE S OF 15N E OF 94W
ASSOCIATED WITH AN UPPER ANTICYCLONE OVER THE SW CARIBBEAN NEAR
10N80W. UPPER DIFFLUENCE ALONG THE SOUTHERN PERIPHERY OF THE
ANTICYCLONE IS SUPPORTING THE CONVECTION ALONG THE MONSOON
TROUGH AND THE EASTERN SEGMENT OF THE ITCZ AS PREVIOUSLY
DESCRIBED.
A SURFACE HIGH PRES RIDGE EXTENDS FROM 31N140W TO NEAR 16N102W.
NE TRADES ARE ENHANCED TO 15-20 KT BETWEEN THE RIDGE AND 05N TO
THE W OF 122W...WITH SEAS OF 6-8 FT IN MIXED LONG PERIOD NW AND
NE SWELL AND STILL MIXING WITH LONG PERIOD CROSS-EQUATORIAL SE
SWELL. THIS AFFECTED AREA S OF THE RIDGE WILL SHRINK WESTWARD
OVER THE NEXT FEW DAYS. NE WINDS OF 15-20 KT NE OF THE RIDGE
WILL SPREAD SE ACROSS THE WATERS N OF 28N BETWEEN 120-130W WITH
SEAS OF 6-9 FT IN MIXED N AND LONG PERIOD S SWELL. THE SEAS WILL
SUBSIDE BEFORE REACHING THE PACIFIC WATERS ALONG THE BAJA
PENINSULA WITH SEAS OF 4-7 FT EXPECTED TILL EARLY MON. GUIDANCE
SHOWS A NEW BATCH OF NW SWELL ARRIVING AT 30N140W LATE SAT AND
REACHING THE NW COAST OF THE BAJA PENINSULA IN THE FORM COMBINED
SEAS OF 6-9 FT ON MON.
$$
NELSON
