000
AXPZ20 KNHC 120249
TWDEP 

TROPICAL WEATHER DISCUSSION      
NWS NATIONAL HURRICANE CENTER MIAMI FL
0405 UTC SAT MAY 12 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 
0200 UTC.

...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH...
MONSOON TROUGH EXTENDS FROM 08N77W TO 10N93W TO LOW PRES AT 
09N106W TO 10.5N109W TO LOW PRES AT 08N113.5W TO 05N122W THEN 
TRANSITIONS TO ITCZ TO THE EQUATOR AT 139W. SCATTERED MODERATE 
TO STRONG CONVECTION S OF TROUGH TO 03N E OF 92W...AND N OF 
TROUGH TO 14N S OF TROUGH TO 04N BETWEEN 92W AND 103W.

ALOFT...
DEEP LAYERED CYCLONE SPINNING NEAR 29N138.5W HAS BEGUN TO LIFT 
NE LATE THIS AFTERNOON AND EVENING AS FORECAST...AND IS CLIPPING 
FAR NW CORNER OF BASIN. ASSOCIATED SURFACE LOW NEAR 28N139W 1015 
MB DRIFTING NE....WHILE ASSOCIATED MID TO UPPER TROUGH EXTENDING 
SW TO A POINT SE OF THE BIG ISLAND OF HAWAII. SECOND VIGOROUS 
CYCLONE OVER N CENTRAL TEXAS CONTINUES TO MOVE SLOWLY E. MID TO 
UPPER SHORTWAVE TROUGH TO THE SW...EXTENDING FROM NW MEXICO TO 
NEAR 15N117W AND MOVING SOMEWHAT IN TANDEM WITH CYCLONE...BUT 
HAS YET TO COME IN PHASE WITH IT. DRY AIR AND SUBSIDENCE WITHIN 
SOUTHERN END OF TROUGH BEGINNING TO IMPINGE UPON NW PORTIONS OF 
ACTIVE CONVECTION IN MONSOON TROUGH...AND SECOND LOW ALONG 
MONSOON TROUGH DESCRIBED ABOVE. BROAD RIDGE BETWEEN CYCLONES 
SHIFTING SLOWLY EWD BETWEEN 20N-30N...BEHIND SHORTWAVE 
TROUGH...AND CURRENTLY ALONG 122W THERE. S OF THESE FEATURES 
LIES TWO TROPICAL RIDGES...ONE CENTERED ON COLLAPSING UPPER 
LEVEL ANTICYCLONE NEAR 07N128W AND EXTENDING N-NE...AND MERGING 
WITH RIDGE DESCRIBED ABOVE...AND A SECOND BROAD RIDGE CENTERED 
ON UPPER ANTICYCLONE NEAR 13N89W EXTENDING N ACROSS MUCH OF THE 
GULF OF MEXICO...AND SPANNING BETWEEN 70W AND 114W. DEEP 
CONVECTION PULSING ALONG AND S OF THE MONSOONAL TROUGH CONTINUES 
TO INDUCE DIVERGENT FLOW ALONG THE S SIDE OF RIDGE BETWEEN 
05N-10N AND IS AIDING IN MAINTAINING THIS PERSISTENT RIDGING 
ALOFT. RIDGING ALOFT ACROSS W PORTIONS OF THE TROPICS IS 
BUILDING NE AND HELPING TO PUSH EWD THE SHORTWAVE TROUGH 
TRAILING SW INTO THE TROPICS. THIS TROUGH IS FORECAST TO 
CONTINUE TO DRIFT E DURING THE WEEKEND AND WEEKEND...BUT NOT 
MAKE IT EWD PAST 110W. IT IS LIKELY TO HAVE A NEGATIVE INFLUENCE 
ON THE CONVECTION IN THE W END OF THE MONSOON TROUGH...AND THE 
LOW CENTER ALONG 113.5W DURING THAT TIME. 

AT LOWER LEVELS...TWO AREAS OF ACTIVE CONVECTION HAVE EVOLVED IN 
THE PAST 24 HOURS...WITH LOW TO MID LEVEL CYCLONIC TURNING 
INDICATED IN SATELLITE IMAGERY...ONE NEAR 08N113.5W AND A SECOND 
NEAR 09N106W. COMPUTER MODEL GUIDANCE HAS NOT BEEN IN AGREEMENT 
THAT PAST SEVERAL RUNS ON THE EVOLUTION OF THESE TWO AREAS OF 
LOW PRESSURE. RECENTLY...CONVECTION ASSOCIATED WITH THE 
WESTERN-MOST LOW HAS DIMINISHED...AS DRIER LOW TO MID LEVEL AIR 
IS SLOWLY REACHING NEAR THIS FEATURE FROM THE NW. MEANWHILE... 
THE MORE EASTERN LOW DOES NOT APPEAR AS WELL ORGANIZED IN 
SATELLITE IMAGERY...AND A PARTIAL 1646 UTC ASCAT PASS DID NOT 
SUGGEST A WELL DEFINED CENTER WITH SIGNIFICANT WINDS. GLOBAL 
MODELS SUGGEST SOME POTENTIAL FOR THIS LOW TO STRENGTHEN AS IT 
LIFTS NW TO N DURING THE NEXT 48 HOURS...AND THE GFS HAS BEEN 
VERY INSISTENT DURING THE PAST SEVERAL RUNS THAT THIS LOW WILL 
INTENSIFY. THIS SYSTEM IS BEING MONITORED FOR POTENTIAL TROPICAL 
CYCLONE DEVELOPMENT...AS IT PRESENTLY COVERED IN OUR OUR HIGH 
SEAS FORECAST UNDER AWIPS HEADER MIAHSFEP2.

ELSEWHERE AT THE LOWER LEVELS...
A WEAK 1018 MB HIGH PRES CENTER HAS DEVELOP JUST NW OF THE AREA 
NEAR 26N128W AND EXTENDS RIDGE SE TO NEAR 16N104W. DUE TO WEAK 
PRES GRADIENT ACROSS W PORTIONS OF THE BASIN...NE TRADEWINDS 
REMAIN BELOW 20 KT N OF THE ITCZ BUT ARE EXPECTED TO INCREASE TO 
20 KT ACROSS FAR W PORTIONS W OF 137W BY 24 HOURS. THE HIGH WILL 
SINK SLIGHTLY SE AND STRENGTHEN TO 1022 MB OVER THE WEEKEND AND 
INDUCE GRADIENT WINDS TO 20 KT ALONG THE W COAST OF BAJA 
CALIFORNIA.   

LONG PERIOD SWELLS YIELDING SEAS UP TO 10 FT PRODUCED BY 
PREVIOUS GALE EVENT WELL N OF BASIN WILL CONTINUE TO AFFECT THE 
WATERS N OF 24N W OF 119W WITH SEAS EXPECTED TO SUBSIDE BELOW 8 
FT BY SAT NIGHT. 

WEAK TROUGH MOVING W ACROSS THE BAY OF CAMPECHE IS EXPECTED TO 
FORCE NLY WINDS ACROSS ISTHMUS INTO GULF OF TEHUANTEPEC BY SUN 
MORNING TO PRODUCE WINDS 20 TO 25 KT...THAT MAY PERSIST THROUGH 
TUE. 

$$
STRIPLING