000
AXPZ20 KNHC 271546
TWDEP 

TROPICAL WEATHER DISCUSSION     
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
1605 UTC SAT JAN 27 2007

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 
1515 UTC.

...ITCZ...

ITCZ AXIS IS CENTERED ALONG 2N78W 8N88W 2N100W 8N135W 7N140W. NO 
SIGNIFICANT CONVECTION.

...DISCUSSION...

FAIRLY ZONAL BUT SLIGHTLY CYCLONIC FLOW IN THE MID/UPPER LEVELS 
EXTENDS ACROSS A GOOD CHUNK OF THE PACIFIC WATERS...ANCHORED BY 
A CUT-OFF AND NEARLY STATIONARY UPPER LOW JUST OFFSHORE SAN 
FRANCISCO CALIFORNIA. ONE EMBEDDED SHORTWAVE TROUGH HAS MOVED 
ACROSS NRN MEXICO AND IS NOW ALONG 102W MOVING INTO THE 
S/CENTRAL PLAINS OF THE UNITED STATES. THIS FEATURE HAS CLEARED 
THE SKIES OVER NRN MEXICO...GENERALLY NW OF A LINE FROM ISLAS 
TRES MARIAS TO MONTERREY/LAREDO. FARTHER W...A WEAK RIDGE IS 
LOCATED ALONG 130W AND IMMEDIATELY PRECEDES A DEEP-LAYERED 
CLOSED LOW MOVING INTO THE AREA NEAR 26N140W. A 1010 MB SURFACE 
LOW IS ASSOCIATED WITH THIS FEATURE NEAR 26N141W AND A COLD 
FRONT EXTENDS FROM 28N140W 25N138W 21N140W. SCATTERED MODERATE 
CONVECTION HAS DEVELOPED WITHIN 75 NM OF THE FRONT FROM 
22N-28N...AND THIS ACTIVITY IS LIKELY TO CONTINUE AS THE LOW 
DRIFTS SE AND WEAKENS. THE SUBTROPICAL JET IS STILL QUITE ACTIVE 
ACROSS THE SRN PERIPHERY OF THE UPPER HEIGHT GRADIENT EXTENDING 
FROM 10N140W NEWD INTO CENTRAL MEXICO. SLIGHT DIFFLUENCE ALOFT 
ON THE SE SIDE OF THE JET IS PRODUCING INCREASED CLOUDINESS AND 
POSSIBLE SHOWERS FROM 10N-20N BETWEEN 102W-112W BUT THERE IS NO 
DEEP CONVECTION.

FARTHER E...A MID-LEVEL RIDGE AXIS IS ALIGNED ALONG THE N COAST 
OF SOUTH AMERICA EXTENDING W ALONG 12N TO 105W AND COVERING MUCH 
OF CENTRAL AMERICA AND THE ADJACENT WATERS WITH MODERATE/STRONG 
SUBSIDENCE. A DISTURBANCE EMBEDDED WITHIN THE ITCZ HAS PULLED 
THE AXIS RATHER FAR TO THE N FOR THIS TIME OF YEAR...NEARLY TO 
THE NICOYA PENINSULA OF COSTA RICA. INCREASED LOW-LEVEL 
CONVERGENCE NEAR THE DISTURBANCE HAS CAUSED MORE 
CLOUDINESS/SHOWERS BETWEEN 85W-95W. INFRARED AND WATER VAPOR 
IMAGERY SHOW A SHARP LINEAR BOUNDARY EXTENDING FROM JUST S OF 
THE EQUATOR NEAR 3S106W NEWD ACROSS NICARAGUA INTO THE W 
CARIBBEAN AND MOVING SE AT 25-30 KT (ABOUT 14 M/S). THE BOUNDARY 
IS PROBABLY A GRAVITY WAVE GENERATED BY THE SUBTROPICAL JET 
(SINCE IT IS PARALLEL TO THE JET AXIS) AND IT HAS BEEN CREATING 
A THIN VEIL OF CIRRUS WHILE ALSO LIGHTENING THE SUBSIDENCE AS IT 
PROPAGATES SE.

A GALE WARNING HAS BEEN ISSUED FOR THE GULF OF TEHUANTEPEC WITH 
WINDS INCREASING TO 35 KT IN 30 HRS (BY SUN AFTERNOON) IN 
RESPONSE TO HIGH PRES BUILDING OVER THE WRN GULF OF MEXICO. THIS 
LOOKS LIKE IT WILL BE A BRIEF (24 HRS OR SO) BUT POSSIBLY STRONG 
EVENT WITH WINDS PEAKING AT 45 KT SUN NIGHT.

$$
BERG