000
AXPZ20 KNHC 210340
TWDEP 

TROPICAL WEATHER DISCUSSION    
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
0405 UTC WED MAR 21 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 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY
THROUGH 0315 UTC.

...ITCZ...

ITCZ IS CENTERED ALONG...7N77W 4N93W 5N101W 2N118W 4N130W 
3N140W. SCATTERED MODERATE ISOLATED STRONG CONVECTION IS NOTED 
WITHIN 15 NM EITHER SIDE OF LINE 6N92W 5N102W 4N109W AND WITHIN 
150 NM EITHER SIDE OF LINE 5N122W 7N136W.

...DISCUSSION...

A PAIR OF MID TO UPPER LEVEL TROUGHS ARE SWEEPING THROUGH THE NW 
PORTION OF THE DISCUSSION AREA WITH THEIR MEAN AXIS ALONG 
32N124W 21N140W. A THIN BAND OF MOISTURE LIES BETWEEN THE TWO 
TROUGHS WITHIN 30 NM EITHER SIDE OF LINE 31N121W 24N135W... 
OTHERWISE DRY UPPER AIR IS NOTED NW OF LINE 17N140W 31N112W. 

AN UPPER LEVEL ANTICYCLONE IS NEAR 5N120W WITH ITS ENVELOPE OF 
ANTICYCLONIC FLOW DOMINATING THE REMAINDER OF THE AREA W OF 
105W. ANOTHER UPPER TROUGH EXTENDS SW ACROSS THE E PORTION OF 
THE AREA...ROUGHLY ALONG 30N101W 14N109W 2N107W. A MOISTURE 
PLUME...ORIGINATING FROM ITCZ CONVECTION BETWEEN 135W AND 
155W...LIES ALONG THE W PERIPHERY OF THE UPPER RIDGE...WITHIN 
300 NM EITHER SIDE OF LINE FROM 8N145W 20N122W TO BEYOND 32N109W 
BUT APPEARS TO SOMEWHAT EVAPORATE N OF 32N OVER ARIZONA. DRY 
UPPER AIR IS TRAPPED ELSEWHERE UNDER THE UPPER RIDGE...AND 
EXTENDS E ACROSS THE REMAINDER OF THE DISCUSSION AREA. UPPER 
DIFFLUENCE OVER THE DEEP TROPICS E OF 107W IS ENHANCING 
CONVECTION ALONG THE ITCZ...WITH ONLY A THIN MOISTURE PLUME 
NOTED MOVING NE ACROSS COSTA RICA. 

AT THE SURFACE...A RIDGE EXTENDS SE INTO THE AREA ALONG 32N142W 
20N105W BRIDGING THROUGH A DISSIPATING COLD FRONT THAT LIES 
ALONG 32N123W 24N130W ACCOMPANIED BY SCATTERED TO LOCALLY BROKEN 
LOW CLOUDS AND ISOLATED SHOWERS ROUGHLY WITHIN 60 NM NW OF THE 
FRONT.

GAP WINDS...SURFACE OBSERVATIONS REPORT N WINDS AT 15-20 KT 
SURROUNDING THE GULF OF TEHUANTEPEC. HIGH RESOLUTION MODELS 
SUGGEST NLY SURGES 20 TO 25 KT THROUGH 48 HOURS...SO INTRODUCED 
INTO TEXT AND GRAPHICAL FORECASTS. TIGHT PRES GRADIENT OVER THE 
W CARIBBEAN IS SPILLING ACROSS CENTRAL AMERICA AT 20-25 KT INTO 
AND DOWNSTREAM OF THE GULF OF PAPAGAYO. LATEST MODEL GUIDANCE 
INDICATES LITTLE CHANGE THROUGH 42 HOURS THEN GRADIENT RELAXES 
SUPPORTING AT 20 KT.

$$
NELSON