000
AXPZ20 KNHC 171518
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
1605 UTC SAT NOV 17 2007

TROPICAL WEATHER DISCUSSION FOR THE EASTERN PACIFIC OCEAN FROM 
THE EQUATOR TO 32N...EAST OF 140W. 

BASED ON 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
1500 UTC.

...ITCZ...

ITCZ AXIS IS CENTERED ALONG 7N77W 5N85W 8N105W 9N125W 9N140W. 
SCATTERED MODERATE/ISOLATED STRONG CONVECTION FROM 3N-7N E OF 
81W. SCATTERED MODERATE WITHIN 45 NM OF AXIS BETWEEN 101W-112W 
AND W OF 123W.

...DISCUSSION...

E OF 105W...
A DEEP LONGWAVE TROUGH WHICH HAS SET UP OVER FAR WESTERN MEXICO 
AND THE ADJACENT WATERS HAS ESSENTIALLY BROKEN DOWN THE UPPER 
RIDGE WHICH WAS LOCATED OVER SE MEXICO AND CENTRAL AMERICA... 
WITH BROAD SW/W FLOW STREAMING FROM THE FAR E PACIFIC WATERS 
INTO THE W CARIBBEAN. HOWEVER...A WELL-DEFINED MID-LEVEL RIDGE 
IS STILL ANCHORED ALONG 18N E OF 105W AND IS PRODUCING MODERATE 
SUBSIDENCE OVER MUCH OF THE REGION...BECOMING STRONGER S OF 7N 
TOWARDS THE EQUATOR. FAIRLY DRY LOW-LEVEL AIR N OF THE ITCZ HAS 
KEPT SKIES MOSTLY CLOUD-FREE WITH THE EXCEPTION OF SCATTERED 
SHOWERS/TSTMS ON THE WINDWARD/EASTERN SIDES OF COSTA RICA AND 
PANAMA. BROKEN STRATOCUMULUS IN STREAMERS LIE S OF THE ITCZ DUE 
TO HIGHER MOISTURE VALUES AND INSTABILITY OVER COOLER OCEAN 
WATERS.

A 1236 UTC QUIKSCAT PASS INDICATED THAT THE GALE HAS ENDED 
WITHIN THE GULF OF TEHUANTEPEC AND WINDS ARE NO HIGHER THAN 
ABOUT 25 KT. WINDS WILL RAPIDLY DIMINISH TODAY AND COULD BE 
BELOW 20 KT BY THIS EVENING...ALTHOUGH DIURNAL EFFECTS COULD 
CAUSE BRIEF INCREASES IN WIND SPEEDS ESPECIALLY SUN MORNING. 
ANOTHER SURGE BEGINS OVERNIGHT SUN INTO MON AND WINDS WILL ONCE 
AGAIN INCREASE TO 25 TO 30 KT...POSSIBLY REACHING NEAR GALE 
CONDITIONS.

W OF 105W...
A DEEP-LAYERED TROUGH AXIS IS SWINGING ACROSS NW MEXICO FROM THE 
TEXAS/NEW MEXICO BORDER TO SRN BAJA CALIFORNIA...AND HAS COME 
INTO PHASE WITH ANOTHER UPPER TROUGH LOCATED DEEPER WITHIN THE 
TROPICS ALONG 110W. MODERATE/STRONG SUBSIDENCE ASSOCIATED WITH 
THE NRN PART OF THE TROUGH IS PUSHING ACROSS MUCH OF NW MEXICO 
AND THE BAJA PENINSULA AND IS PROVIDING AN EFFICIENT CAP TO THE 
MARINE LAYER W OF BAJA...WITH COASTAL FOG/STRATUS BANKED OVER 
THE W COAST N OF 26N. W OF THE TROUGH...A NE/SW ORIENTED UPPER 
RIDGE EXTENDS FROM 28N140W TO 30N130W AND IS PROVIDING 
ADDITIONAL SUBSIDENCE N OF 24 ON THE CUSP OF A 50 KT WESTERLY 
SUBTROPICAL JET. THE JET ORIGINATES FROM A LARGE CUT-OFF LOW 
LOCATED ABOUT 300 NM SE OF THE BIG ISLAND OF HAWAII...AND BROAD 
DIFFLUENCE E OF THE LOW IS PRODUCING WIDESPREAD MID/HIGH LEVEL 
CLOUDINESS LYING WITHIN A BELT BETWEEN 9N-24N FLOWING E TOWARDS 
MEXICO. MODEL GUIDANCE HAS BEEN SUGGESTING THAT SURFACE LOW PRES 
MAY DEVELOP BENEATH THIS AREA OF DIVERGENCE OVER THE NEXT 48 HRS 
OR SO BUT IT IS EXPECTED TO REMAIN W OF 140W AND MAY ONLY 
INCREASE WINDS A BIT OVER THE FAR WRN PART OF THE DISCUSSION 
AREA.

$$
BERG