000
AXPZ20 KNHC 270935
TWDEP 

TROPICAL WEATHER DISCUSSION 
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
1005 UTC THU MAY 27 2010

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

BASED ON 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
0715 UTC.

...SPECIAL FEATURE...
A BROAD AREA OF LOW PRESSURE LIES WITHIN A COUPLE HUNDRED MILES 
SOUTH OF THE GULF OF TEHAUNTEPEC WITH A WEAK 1007 MB SURFACE LOW 
IDENTIFIED SOUTH OF THE MEXICO/GUATEMALA BORDER NEAR 13N93W. 
NUMEROUS MODERATE TO STRONG CONVECTION LIES WITHIN 210 NM NE 
QUADRANT AND BETWEEN 120 NM AND 270 NM SE QUADRANT OF THE LOW AS 
WELL AS WITHIN 240 NM W SEMICIRCLE EXCEPT OUT FURTHER TO 360 NM 
W QUADRANT. WHILE MOST OF THE CONVECTION CURRENTLY LIES 
OFFSHORE...THIS SYSTEM IS EXPECTED TO PRODUCE VERY HEAVY 
RAINFALL AND FLOODING OVER PORTIONS OF CENTRAL AMERICA DURING 
THE NEXT FEW DAYS...REGARDLESS OF THE POTENTIAL FOR DEVELOPMENT. 
THERE IS A MEDIUM CHANCE OF THIS SYSTEM BECOMING A TROPICAL 
CYCLONE OVER THE NEXT 48 HOURS. 

...ITCZ...
THE INTERTROPICAL CONVERGENCE ZONE AXIS IS ALONG 10N93W TO 
07N100W TO 06N110W TO 06N121W TO 08N140W. SCATTERED MODERATE 
CONVECTION LIES WITHIN 75 NM N OF THE ITCZ AXIS BETWEEN 118W AND 
123W.

...DISCUSSION...
THE SOUTHERN STREAM 50-70 KT UPPER JET CORE LIES FROM 15N140W TO 
25N105W 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 SENT A DISSIPATING COLD FRONT INTO N 
CENTRAL WATERS FROM 30N121W TO 27N132W. A NEW SURGE OF NW SWELL 
ASSOCIATED WITH THE SYSTEM HAS MOVED INTO N CENTRAL 
WATERS...BRINGING WAVE HEIGHTS TO 8 FT. ZONALLY ELONGATED 
SHORTWAVE ENERGY ALOFT NEAR 20N130W IS BEING PULLED 
NORTHEASTWARD BY THIS TROUGH AND IS EXPECTED TO AMPLIFY THE MID 
TO UPPER LEVEL PATTERN OVER N WATERS. THIS WILL TURN THE UPPER 
JET MORE NE TO SW...WITH INCREASED DIFFLUENCE ALOFT EXPECTED 
NEAR THE JET INFLECTION POINT AROUND 120W...MAKING THE 
INTERSECTION OF THE ITCZ AND THIS AREA OF UPPER DIFFLUENCE NEAR 
120W A CANDIDATE FOR INCREASED CONVECTION OVER THE NEXT FEW DAYS.

THE BROAD CYCLONIC GYRE IN THE MID AND LOW LEVEL 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. THIS GYRE 
CONTINUES TO HOLD THE POOL OF MID TO LOW LEVEL MOISTURE CLOSE TO 
THE COAST OF CENTRAL AMERICA SOUTH OF THE GULF OF TEHUANTEPEC. 
FLOW ALOFT OVER THE REGION WILL REMAIN BROADLY DIFFLUENT OVER 
THE FORECAST PERIOD. THE ABUNDANT MOISTURE WOULD LIKELY BE 
TAPPED INTO BY THE SHORTWAVE ENERGY THAT MOVES OVER CENTRAL 
AMERICA...BRINGING ANOTHER ROUND OF HEAVY RAIN TO THE ALREADY 
WATER LOGGED REGION. THE 0404 UTC ASCAT PASS CONTINUES TO SHOW 
20-25 KT SW WINDS FEEDING INTO THE LOW LEVEL CIRCULATION. THESE 
WINDS ARE EXPECTED TO CONTINUE PRIMARILY SOUTH OF THE LOW 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.

$$
SCHAUER