000
AXPZ20 KNHC 210922
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
1005 UTC THU SEP 21 2006

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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
0845 UTC.

...ITCZ...
AXIS ALONG 9N80W 8N93W 10N109W 7N127W 7N140W. SCATTERED MODERATE 
TO STRONG CONVECTION WITHIN 45 NM OF 5N78W. ISOLATED MODERATE 
NEAR 7N87W 10N92W 7N100W 7N108W AND 7N117W. SCATTERED MODERATE 
WITHIN 45 NM OF 7N124W 14N129W AND 7N136W.

OTHER SCATTERED MODERATE CONVECTION N OF 10N BETWEEN 88W AND 95W 
AND WITHIN 45 NM OF 17N106W.

...TROPICAL WAVES...

TROPICAL WAVE 135W S OF 17N MOVING W 10 TO 12 KT. FLAIR UP OF 
CONVECTION ALONG THE ITCZ PAST FEW HOURS NOW BEGINNING TO 
WEAKEN.  

TROPICAL LOWS...

 A 1010 MB LOW NEAR 17N106W IS MOVING W 10 KT. SCATTERED 
MODERATE CONVECTION N AND S OF THE CENTER. SOME POSSIBLE 
CYCLONIC ROTATION IN MID CLOUDS BUT NO ORGANIZATION TO THE 
CONVECTION. 

A 1012 MB LOW...REMNANTS OF TROPICAL DEPRESSION MIRIAM IS 
LOCATED ABOUT 100 NM W OF THE LOWER BAJA COAST. THE LOW IS 
MOVING SE 10 KT.   

...DISCUSSION...

A STRONG SHORTWAVE TROUGH WAS MOVING OVER THE SW US TONIGHT AND 
WILL BRUSH NRN MEXICO AND WEAKEN A ALREADY WEAK MID LEVEL RIDGE. 
A WEAK UPPER LOW WAS LOCATED NEAR 27N130W AND WATER VAPOR 
IMAGERY SHOWS VERY DRY AIR IN IT'S CIRCULATION. A STRONG MID 
LEVEL RIDGE LIES NW OF THE REGION. ON THE SURFACE TONIGHT THE 
PACIFIC RIDGE EXTENDS OVER THE NW PORTION FROM 30N135W TO 
12N110W. NE TRADES TO 20 KT WERE MAINLY N OF 15N AND W OF 130W. 
GAP WINDS REMAIN LIGHT WHILE CROSS EQUATORIAL SLY WINDS WERE 
STRONGEST S OF 7N BETWEEN 105W AND 130W ACCORDING TO QUIKSCAT 
AND SSMI PASSES.

LATER DAY 1 THE MID LEVEL RIDGE RUPTURES ALONG 100W ACCORDING TO 
THE GFS MODEL AS THE STRONG SHORTWAVE PASSES BY TO THE N. THE 
CUTOFF LOW MOVES TO NEAR 25N130W VIRTUALLY STATIONARY AND CAUGHT 
IN A LARGE FLAT RIDGE. ON THE SURFACE LITTLE CHANGE TO THE 
PACIFIC RIDGE OR NE TRADES. WINDS ALONG THE BAJA COAST REMAIN 
LIGHT NWLY THANKS TO A WEAK PRESSURE GRADIENT. GAP WINDS REMAIN 
LIGHT AND CROSS EQUATORIAL SLY WINDS S OF 5N WILL BE STRONGEST W 
OF 110W.

FOR DAY 2 THE SECOND IN A SERIES OF STRONG SHORTWAVE TROUGHS 
WILL DROP SE OVER THE SW US DEPRESSING THE MID LEVEL RIDGE THAT 
CONTINUES OVER MEXICO. THE RIDGE EXTENDS WSW TO NEAR 16N130W AND 
IS TRYING TO JOIN UP WITH THE MID LEVEL RIDGE NW OF THE AREA. 
THE CUTOFF LOW DRIFTS NE TO NEAR 27N129W INFLUENCED BY THE 
STRONG TROUGH OVER THE CONTINENTAL US. ON THE SURFACE DAY 2 THE 
PACIFIC RIDGE IS FORECAST TO WEAKEN SOME WITH A DECREASE IN NE 
TRADES W OF 130W. THE GFS MODEL SHOWS SURFACE PRESSURES LOWERING 
OFF THE S CA COAST. THIS WILL TIGHTEN THE PRESSURE GRADIENT 
BETWEEN 120W AND 130W WITH NLY WINDS INCREASING N OF 28N TO 20 
KT AND N SWELL INCREASING TO 9 FT. GAP WINDS WILL REMAIN LIGHT 
AND CROSS EQUATORIAL SLY WINDS SHOULD BE LIGHT TO MODERATE S OF 
6N BETWEEN 100W AND 130W.

$$
RRG