Hurricane Advisories Hurricane advisories

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
0405 UTC TUE MAY 15 2012

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 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
0215 UTC.

...SPECIAL FEATURE...
NEWLY UPGRADED TROPICAL STORM ALETTA WAS LOCATED NEAR 10.5N
108.5W 1004 MB AT 0300 UTC MAY 15 MOVING W OR 280 DEG AT 10 KT.
MAXIMUM SUSTAINED WINDS 35 KT GUSTS 45 KT. CONVECTION HAS
INCREASE THIS EVENING NEAR THE CENTER OF ALETTA...WITH
THUNDERSTORM TOPS COOLING. THE IMPROVED SATELLITE PRESENTATION
SUGGEST THE SYSTEM HAS INCREASED TO TROPICAL STORM STRENGTH. THE
CORE OF ALETTA IS SMALL AND EXPECTED TO MOVE WEST TO WEST
NORTHWEST OVER THE NEXT 48 HOURS. AFTER THAT...ADVERSE UPPER
LEVEL WINDS TO THE WEST ARE EXPECTED TO WEAKEN THIS SYSTEM
RATHER QUICKLY...SO THERE IS A SHORT WINDOW OF OPPORTUNITY FOR
THIS SYSTEM TO FURTHER INTENSIFY. WINDS ARE EXPECTED TO INCREASE
AND PEAK NEAR 45 KT TUE NIGHT OR EARLY WED MORNING...BEFORE
WEAKENING COMMENCES.

...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH...
MONSOON TROUGH EXTENDS FROM 07N76W TO 10.5N85W TO LOW PRES NEAR
08N92W 1007 MB TO 12N102W...WHERE T.S. ALETA HAS SEPARATED FROM
TROUGH...THEN TROUGH RESUMES FROM NEAR 09N105W TO 07N112W TO LOW
PRES NEAR 07N123W 1008 MB TO 05N125W...THEN TRANSITIONS TO ITCZ
CONTINUING ON TO BEYOND 03N140W. SCATTERED TO LOCALLY NUMEROUS
MODERATE TO STRONG CONVECTION IS NOTED WITHIN 120 NM EITHER SIDE
OF TROUGH BETWEEN 81W AND 87W. SCATTERED TO NUMEROUS MODERATE TO
STRONG CONVECTION NOTED WITHIN 150 NM N AND 30 NM S OF TROUGH
BETWEEN 95W AND 102W. SCATTERED MODERATE CONVECTION NOTED WITHIN
150 NM N OF ITCZ W OF 136W.

...DISCUSSION...
ALOFT...FLAT MID/UPPER LEVEL RIDGE IS HOLDING ITS POSITION N OF
20N ALONG ABOUT 125W N TO 31N WHILE SHORTWAVE ENERGY WITHIN A
SHARP LONGWAVE TROUGH PERSISTING W OF 140W SHIFTS NE THROUGH
TROUGH. TROPICAL RIDGING TO THE SE CONTINUES ALONG AND N OF THE
MONSOON TROUGH...WITH UPPER ANTICYCLONE CENTERED NEAR
12N88W...AND HAS SHIFTED SLIGHTLY WWD PAST 24 HOURS IN RESPONSE
TO WWD SHIFTING DEEP CONVECTIVE OUTBURST CURRENTLY BETWEEN 88W
AND 96W...ALTHOUGH CONVECTION HAS DIMINISHED PAST COUPLE OF
HOURS THERE. LIGHT ANTICYCLONIC SHEAR ALONG S SIDE OF RIDGE
PROVIDING FAVORABLE ENVIRONMENT FOR DEEP CONVECTIVE GROWTH.
RIDGE EXTENDS NE ACROSS W CARIB TO BEYOND THE BAHAMAS...AND W-NW
TO NEAR 17N116W.

AT LOWER LEVELS...HIGH PRES CENTER 1024 MB AT 28N131W EXTENDS
RIDGE SE TO NEAR 18N110W. PRES GRADIENT BETWEEN CENTER AND WEAK
LOW PRES OVER SOUTHERN CALIFORNIA IS MAINTAINING FRESH TO STRONG
NW BREEZE TO 25 KT ALONG BAJA CALIFORNIA W COAST S TO 24N WITH
SEAS TO 9 FT. THIS HIGH PRES IS FORECAST TO SHIFT NW AND
REORGANIZE JUST N OF AREA DURING THE 48 HOURS...AND WILL
MAINTAIN FRESH TO STRONG NWLY WINDS ACROSS BAJA CALIFORNIA NORTE
N OF 28N INTO THE WEEKEND.

STATIONARY FRONT OVER THE ERN BAY OF CAMPECHE AND A WAVE LIKE
FEATURE ALONG ABOUT 92W IN THE EPAC ARE COMBINING TO MAINTAIN
STRONG NLY WINDS ACROSS CHIVELA PASS AND EXITING THROUGH GULF OF
TEHUANTEPEC. WINDS HAVE DROPPED FROM GALE FORCE TO 30 KT LATE
THIS AFTERNOON AND EVENING...AND WILL DIMINISH TO A NARROW PLUME
OF 20-25 KT BY TUE AFTERNOON...AND THEN BLOW AROUND 20 KT
CONFINED JUST TO THE BAY THROUGH 48 HOURS.

FRESH ELY WINDS OVER GULF OF PAPAGAYO HAVE DIMINISHED TO LESS
THAN 20 KT THIS EVENING.

THE WAVE LIKE DISTURBANCE ALONG ABOUT 92W HAS SHOWN SOME MIDDLE
LEVEL CYCLONIC TURNING IN SATELLITE IMAGERY THIS AFTERNOON AND
EVENING. THIS FEATURE IS EXPECTED TO CONTINUE TO PRODUCE ACTIVE
CONVECTION FOR THE NEXT FEW DAYS AS IT SHIFTS SLOWLY WWD.

$$
STRIPLING