000
AXPZ20 KNHC 271607
TWDEP 

TROPICAL WEATHER DISCUSSION 
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
1605 UTC THU MAY 27 2010

TROPICAL WEATHER DISCUSSION FOR THE EASTERN PACIFIC OCEAN FROM 
THE EQUATOR TO 32N...EAST OF 140W. 

BASED ON 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
1415 UTC.

...SPECIAL FEATURE...
A BROAD AND ELONGATED CYCLONIC GYRE LIES FROM THE GUATEMALA AND 
EL SALVADOR COASTS SW TO NEAR 09N100W...WITH AN EMBEDDED 1006 MB 
LOW PRESSURE CENTER ESTIMATED NEAR 12.5N95W. ALTHOUGH 
SCATTEROMETER PASSES FROM YESTERDAY AND LAST NIGHT IDENTIFIED 
LOW PRESSURE CENTERS FARTHER N ALONG 13.5N...SATELLITE PHOTOS 
THIS MORNING SUGGEST THAT MID LEVEL TURNING IS IMPROVING NEAR 
THIS NEWER ESTIMATED CENTER...AND THE SYSTEM MAY BE BECOMING 
BETTER ORGANIZED. COMPUTER MODEL GUIDANCE ALSO SUGGESTS A BRIEF 
SW DRIFT OF PREVIOUS SURFACE LOWS THAT EVENTUALLY TAKE A 
CYCLONIC TURN AND THEN BEGIN TO MOVE E-NE OVER THE NEXT FEW 
DAYS. NUMEROUS MODERATE TO STRONG CONVECTION LIES WITHIN 240 NM 
NE AND 180 NM SE QUADRANTS...AND WITHIN 360 NM NW SEMICIRCLE. 
WHILE MOST OF THE CONVECTION CURRENTLY LIES OFFSHORE...THIS 
SYSTEM IS EXPECTED TO PRODUCE CONTINUE TO PRODUCE PERIODS OF 
VERY HEAVY RAINFALL LEADING TO FLASH FLOODING AND MUDSLIDES OVER 
PORTIONS OF CENTRAL AMERICA FROM THE TEHUANTEPEC AREA TO 
NICARAGUA DURING THE NEXT FEW DAYS...REGARDLESS OF THE 
DEVELOPMENT OF A TROPICAL CYCLONE OR NOT. THERE IS A MEDIUM 
CHANCE OF THIS SYSTEM BECOMING A TROPICAL CYCLONE OVER THE NEXT 
48 HOURS. 

...ITCZ...
THE INTERTROPICAL CONVERGENCE ZONE AXIS WAS ALONG 13N87W TO 
08N94W TO 07N116W TO 08N134W TO 07N140W. NUMEROUS STRONG 
CONVECTION WAS OCCURRING WITHIN 120 NM EITHER SIDE OF AXIS E OF 
91W. SCATTERED MODERATE TO STRONG CONVECTION WAS WITHIN 60 NM OF 
AXIS BETWEEN 118W AND 126W.

...DISCUSSION...
THE SOUTHERN STREAM 50-70 KT UPPER JET CORE LIES FROM 16N140W TO 
20N110W AND IS TRANSPORTING UPPER LEVEL MOSITURE ASSOCIATED WITH 
ITCZ CONVECTIVE BLOW OFF W OF THE AREA INTO THE REGION W OF 130W 
BETWEEN 11N AND 15N. TO THE NORTH OF THE JET LIES A WEAKENING 
DEEP LAYER TROUGH THAT HAS TRANSPORTED A WEAKENING COLD FRONT 
INTO THE N CENTRAL WATERS FROM 30N119W TO 23N134W. A NEW SURGE 
OF NW SWELL ASSOCIATED WITH THE SYSTEM HAS MOVED INTO N CENTRAL 
WATERS...BRINGING WAVE HEIGHTS TO 8 FT ALONG 30N. A ZONALLY 
ELONGATED SHORTWAVE ALOFT NEAR 20N130W IS BEING PULLED 
NORTHEASTWARD BY THIS TROUGH AND IS EXPECTED TO AMPLIFY THE MID 
TO UPPER LEVEL PATTERN OVER N WATERS DURING THE NEXT 36 HOURS.  
THIS WILL TURN THE UPPER JET MORE NE TO SW...WITH INCREASED 
DIFFLUENCE ALOFT EXPECTED NEAR THE JET INFLECTION POINT AROUND 
120W...MAKING THE AREA OF UPPER DIFFLUENCE NEAR 120W A LIKELY 
CANDIDATE FOR INCREASED ITCZ CONVECTION OVER THE NEXT FEW DAYS.

THE BROAD AND ELONGATED CYCLONIC GYRE IN THE MID AND LOW LEVELS 
OVER THE FAR E PORTIONS...AND SUPPORTING THE SYSTEM NOTED IN THE 
SPECIAL FEATURES SECTION IS ALSO FORECAST TO BECOME ORIENTED 
MORE NE TO SW OVER THE NEXT FEW DAYS WITH MUCH OF THE FORECAST 
GUIDANCE SHOWING SOME OF THE SHORTWAVE ENERGY SHEDDING E AWAY 
FROM THE GYRE INTO THE CARIBBEAN...AS THE SWLY FLOW ON THE S 
SIDE OF THE TROUGH AXIS REMAINS DOMINANT. THIS GYRE CONTINUES TO 
HOLD THE POOL OF HIGH LEVELS OF MID TO LOW LEVEL MOISTURE WITHIN 
THE GYRE AND EXTENDING OVER CENTRAL AMERICA SOUTH OF THE GULF OF 
TEHUANTEPEC. DEEP CONVECTION WILL PERSIST ACROSS THE VERY MOIST 
AND UNSTABLE REGION FOR THE NEXT COUPLE OF DAYS AND HELP TO 
MAINTAIN BROAD ANTICYCLONIC AND DIFFLUENT UPPER LEVEL FLOW OVER 
THE GYRE. PULSING MODERATE TO STRONG CONVECTION YIELDING HEAVY 
TO TORRENTIAL RAINS WILL AFFECT THIS ALREADY WATER LOGGED REGION 
THROUGH SAT EVENING...MAINTAINING HIGH FLASH FLOOD AND MUDSLIDE 
POTENTIAL ALONG THE WRN SLOPES OF THESE MOUNTAINOUS COUNTRIES.  
THE 0404 UTC ASCAT PASS CONTINUED TO SHOW 20-25 KT SW WINDS 
FEEDING INTO THE LOW LEVEL CIRCULATION. THESE WINDS ARE EXPECTED 
TO CONTINUE PRIMARILY SOUTH OF THE TROUGH OVER THE NEXT FEW 
DAYS. THIS PERSISTENT SW WIND COUPLED WITH SW SWELL HAS ALLOWED 
FOR SIGNIFICANT WAVE HEIGHTS TO REACH 12 FEET IN ASSOCIATION 
WITH THIS SYSTEM. WHILE THE SW SWELL IS FORECAST TO SUBSIDE OVER 
THE NEXT TWO DAYS...ANY FURTHER DEVELOPMENT OF THE SYSTEM WOULD 
LIKELY HOLD THE MAXIMUM WAVE HEIGHT TO AROUND 12 FT.

AT THE SURFACE...A 1024 MB SURFACE HIGH LIES NEAR 28N149W AND 
SPROUTS A RIDGE SOUTHEASTWARD THROUGH FORECAST WATERS FROM 
25N140W TO NEAR 19N113W. THIS HIGH WILL BE FORCED NORTHEASTWARD 
OVER THE NEXT FEW DAYS AHEAD OF A DEEP LAYER TROUGH OVER THE 
CENTRAL NORTH PACIFIC AND THE RIDGE AXIS WILL SHIFT E AS A 
RESULT. THE AREA OF FRESH TO STRONG NE TRADE WINDS FOUND W OF 
130W BETWEEN 10N AND 17N WILL DIMINISH A NOTCH AND SHRINK W 
TODAY AS THE WEAKENED HIGH SLIDES NE BUT IS EXPECTED TO EXPAND 
AGAIN TO 130W FRI AS THE HIGH BECOMES REINVIGORATED UNDER AN 
INCREASINGLY MORE AMPLIFIED DEEP LAYER PATTERN. MEANWHILE...NW 
WINDS BETWEEN THE RIDGE AXIS AND THE TROUGHING OVER THE SW U.S. 
AND ON THE LEE SIDE OF THE SIERRA MADRE OCCIDENTAL IS EXPECTED 
TO CONTINUE TO BE STRONG ENOUGH TO GENERATE 20 KT NW WINDS ALONG 
THE W COAST OF BAJA CALIFORNIA THROUGH TODAY...WITH THE AREA OF 
WINDS EXPECTED TO EXPAND AND WIND SPEED EXPECTED TO INCREASE TO 
25 KT ON FRI AS THE SURFACE HIGH BUILDS.

$$
STRIPLING