000
AXPZ20 KNHC 201619
TWDEP 

TROPICAL WEATHER DISCUSSION    
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
1605 UTC FRI APR 20 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 9N86W 7N95W 9N105W 7N115W 6N125W 
4N130W 2N140W. SCATTERED MODERATE CONVECTION IS WITHIN 90 NM
EITHER SIDE OF THE AXIS BETWEEN 94W-97W...ALSO BETWEEN 110W-118W 
WITHIN...AND WITHIN 30 NM EITHER SIDE OF THE AXIS BETWEEN 
129W-131W. SCATTERED MODERATE/ISOLATED STRONG CONVECTION EXISTS
FROM 4N-9N E OF 86W.

...DISCUSSION...

A DEEP LAYERED CYCLONIC CIRCULATION LOCATED N OF THE AREA JUST
OFF THE SRN CALIFORNIA COAST APPROACHING LAOS ANGELES IS DIVING 
SEWD AROUND 25-30 KT. A DEEP LAYERED TROUGH EXTENDS SW FROM THE
CIRCULATION CENTER SW THROUGH 26N124W 24N130W TO A WEAKENING 
MID/UPPER LEVEL CYCLONIC CIRCULATION NEAR 23N139W. THE TROUGH IS 
SWINGING EWD TOWARDS NRN BAJA CALIFORNIA...AND IS FORECAST TO 
MOVE E OF THE DISCUSSION AREA THROUGH SAT NIGHT. MID/UPPER LEVEL 
RIDGING IS W OF THE AREA IS TILTING EWD WITH TIME...AND IS 
BEGINNING TO INTRUDE INTO THE FAR WRN PORTION OF THE AREA N OF 
THE TROUGH W OF 131W. A 270 NM SWATH OF MODERATE SUBSIDENCE AND 
ASSOCIATED DRY AIR IS NOTED TO THE S OF THE TROUGH. THE RIDGE IS 
FORECAST TO FILL IN ACROSS THE NRN PORTION OF THE AREA N OF 19N 
W OF 120W ONCE THE TROUGH EXITS THE AREA. A SUBTROPICAL JET 
STREAM BRANCH EXTENDS INTO THE REGION THROUGH 15N140W AND 
CONTINUES ENE THROUGH 19N130W 21N120W TO JUST S OF THE SRN TIP 
OF BAJA CALIFORNIA AND NEWD ACROSS NW MEXICO. MAXIMUM JET CORE 
WINDS AS INDICATED BY SATELLITE DERIVED WINDS ARE IN THE 70-100 
KT RANGE.

OVER THE ERN SECTION...THE FLOW BECOMES DIFFLUENT E OF 105W.
THIS FLOW PATTERN IS AIDING ITCZ CONVECTION BETWEEN 94W-97W...AND
IS ALSO ADVECTING SCATTERED TO BROKEN MID TO HIGH LEVEL CLOUDS
NEWD FROM THE ITCZ ACROSS CENTRAL AMERICA. BROAD MID/UPPER LEVEL
RIDGING E OF THE DIFFLUENT FLOW PATTERN COVERS THE NRN PART OF S 
AMERICA AND MUCH OF THE WRN CARIBBEAN AND CENTRAL AMERICAN LAND 
BASIN. THE FLOW BETWEEN BOTH THE RIDGE AND THE DIFFLUENCE IS 
IS ALSO SPREADING HIGH LEVEL DEBRIS CLOUDINESS NWD TOWARDS 
THE SE PORTION OF CENTRAL AMERICA. A WEAK UPPER LEVEL CYCLONIC
CIRCULATION MOVING SWD ABOUT 15 KT IS NOTED NEAR 2N104W.

AT THE SFC...THE SURFACE REFLECTION OF THE DEEP-LAYERED TROUGH
MENTIONED ABOVE IS SEEN AS COLD FRONT MOVING ESE 20-25 KT 
EXTENDING FROM 30N124W TO 30N136W. THE FRONT IS FOLLOWED BY NW 
WINDS OF 20-25 KT BETWEEN 124W-131W. A 1027 MB HIGH CENTER IS 
ANALYZED NW OF THE DISCUSSION AREA NEAR 32N146W WITH A RIDGE 
EXTENDING SEWD THROUGH 27N138W 24N129W TO 23N119W. HIGH PRES 
COVERS THE AREA N OF 16N W OF 121W. THE PRES GRADIENT RESULTING 
FROM THE RIDGE IS RESULTING IN TRADES OF 20-25 KT FROM 8N-23N W 
OF 125W. NW WINDS OF 20 KT RESULTING BETWEEN THE PRES DIFFERENCE 
BETWEEN THE HIGH AND BROAD LOW PRES OVER MEXICO ARE EVIDENT N OF 
26N E OF 120W TO THE COAST OF BAJA CALIFORNIA. THESE WINDS 
SHOULD SLOWLY DECREASE IN AREAL COVERAGE THROUGH THE NEXT 48 HRS 
AS THE HIGH SLOWLY MOVES E AND WEAKENS.

$$
AGUIRRE