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AXPZ20 KNHC 281533
TWDEP

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
1605 UTC THU MAY 28 2015

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 1530 UTC.


...SPECIAL FEATURE...

CONVECTION ASSOCIATED WITH TROPICAL DEPRESSION ONE-E HAS BECOME BETTER ORGANIZED AND THE SYSTEM HAS BEEN UPGRADED TO TROPICAL STORM ANDRES. ANDRES WAS CENTERED NEAR 11.6N 110.3W AT 1500 UTC MAY 28 WITH MAXIMUM SUSTAINED WINDS OF 35 KT WITH GUSTS TO 45 KT. THE MINIMUM CENTRAL PRESSURE WAS 1002 MB. ANDRES IS MOVING WNW OR 295 DEG AT 12 KT. NUMEROUS STRONG CONVECTION WAS NOTED WITHIN 90 NM IN THE SOUTHERN AND 75 NM IN THE NORTHERN SEMICIRCLES OF ANDRES. SCATTERED MODERATE TO STRONG WITHIN 45-60- NM EITHER SIDE OF A LINE FROM 11N118W TO 09N116W TO 08N113W. SCATTERED MODERATE ISOLATED STRONG ELSEWHERE WITHIN 360 NM N AND 180 NM S SEMICIRCLES OF CENTER.

ANDRES IS FORECAST TO STRENGTHEN FURTHER OVER THE NEXT 24 TO 48 HOURS...REACHING HURRICANE INTENSITY SOMETIME ON FRI AND MAINTAINING HURRICANE INTENSITY THROUGH THE WEEKEND. ANDRES IS FORECAST TO TRACK S OF A MID TO UPPER RIDGE FOR A COUPLE OF DAYS...THEN TURN MORE TO TOWARDS THE N-NW. REFER TO LATEST NHC PUBLIC/FORECAST ADVISORIES UNDER AWIPS/WMO HEADERS MIATCPEP1/MIATCMEP1 AND WTPZ31/WTPZ21 KNHC FOR MORE DETAILS.


...TROPICAL WAVES/LOWS...

A TROPICAL WAVE EXTENDS FROM FROM 05-14N ALONG 98W/99W AND HAS BEEN PROGRESSING W AT 10 KT OVER THE PAST 24 HOURS. CURRENTLY ISOLATED MODERATE TO STRONG CONVECTION IS OBSERVED WITHIN 30 NM OF WAVE AXIS AT 07N. THE WAVE IS FORECAST TO CONTINUE W TODAY AND GRADUALLY LOSE IDENTITY AS IT BECOMES ABSORBED INTO THE BROADER CYCLONIC CIRCULATION ASSOCIATED WITH TROPICAL STORM ANDRES.

A 1007 MB SURFACE LOW PRESSURE IS ANALYZED NEAR 08N123W WITH SCATTERED MODERATE ISOLATED STRONG WITHIN 240 NM W AND NW QUADRANTS OF THE LOW PRES. MARGINAL PRESSURE GRADIENT BETWEEN LOW PRES AND RIDGE OF HIGH PRES TO THE N IS SUPPORTING NE TRADES OF 15-20 KT ROUGHLY FROM 11-18N BETWEEN 115-130W WITH COMBINED SEAS OF 6-8 FT PRIMARILY DUE TO LONG PERIOD SOUTHERLY SWELL. THE LOW IS FORECAST TO DRIFT TO NEAR 09N124W FRI...AND THEN DISSIPATE LATE FRI.

A 1008 MB LOW PRES IS ANALYZED NEAR 11N133W WITH SCATTERED MODERATE TO STRONG CONVECTION WITHIN 120 NM OF CENTER. A STRONGER PRESSURE GRADIENT BETWEEN THIS LOW AND HIGH PRES TO THE N IS MAINTAINING NE-E 20-25 KT TRADES WITHIN 360 NM OF THE NW SEMICIRCLE OF CENTER WITH COMBINED SEAS TO 9 FT. THE LOW IS FORECAST TO CONTINUE WSW TO NEAR 10N137W FRI AND NEAR 09N140W ON ON SAT.


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

CURRENTLY THERE IS NOT A WELL DEFINED MONSOON TROUGH OR ITCZ. A SURFACE LOW OVER NW COLOMBIA HAS AN ASSOCIATED TRAILING TROUGH SW ACROSS NE COLOMBIA AND ACROSS THE EPAC THROUGH 07N77W TO 07N85W. SCATTERED MODERATE ISOLATED STRONG CONVECTION IS FLARING WITHIN 120 NM OF THE TROUGH.


...DISCUSSION...

AN UPPER CYCLONE IS OBSERVED NW OF THE AREA NEAR 37N150W WITH AN UPPER TROUGH EXTENDING S TO 17N150W. ASSOCIATED SURFACE FRONTS ARE ROTATING E INTO THE FAR NW PORTION OF THE DISCUSSION AREA. THE NEXT COLD FRONT WILL REACH ALONG A POSITION FROM 32N136W TO 27N140W ON FRI...AND FROM 32N128W TO 25N140W ON SUN BUT ONLY BE ACCOMPANIED BY A 5-10 KT SW-W-NW WIND SHIFT ACROSS THE DISCUSSION WATERS. A SHORTWAVE RIDGE EXTENDS N FROM THE TROPICS ALONG 125W. UPPER DEBRIS MOISTURE IS MOVING ACROSS THE RIDGE AND SPILLING SE OVER SOUTHERN CALIFORNIA. OTHERWISE...THE UPPER LEVELS APPEAR VERY DRY ACROSS THE SUBTROPICAL PORTION.

AN UPPER ANTICYCLONE IS CENTERED OVER THE TROPICS NEAR 14N103W WITH AN UPPER RIDGE EXTENDING WESTWARD TO BEYOND 10N140W. AN UPPER RIDGE ALSO EXTENDS E TO A CREST EASTWARD TO 10N90W. THE ASSOCIATED UPPER DIFFLUENCE IS ENHANCING CONVECTION ASSOCIATED WITH TROPICAL STORM ANDRES AND PROVIDING A FAVORABLE ENVIRONMENT FOR INTENSIFICATION...REFER TO THE SPECIAL FEATURES SECTION ABOVE FOR ADDITIONAL INFORMATION ON ANDRES.

GULF OF TEHUANTEPEC...EXPECT A BRIEF NORTHERLY SURGES TO 20-25 KT AT TIMES OF DIURNALLY DRIVEN DRAINAGE FLOW THROUGH THE NEXT 36 HOURS BEFORE WINDS DROP BELOW 20 KT ALTOGETHER. SEAS ARE EXPECTED TO REMAIN BELOW 8 FT THROUGH THE NEXT 48 HOURS. THE PATTERN WILL REPEAT AGAIN LATE TONIGHT.

GULF OF PAPAGAYO...ENE WINDS OF 20-25 KT HAVE DIMINISHED AFTER THE PEAK DIURNAL . ANY PULSES FORECAST THROUGH FRI SHOULD ONLY BE IN THE 15-20 KT RANGE.

$$ COBB

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