000
AXPZ20 KNHC 142110
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
2205 UTC MON SEP 14 2009

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

BASED ON 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
2000 UTC.

...SPECIAL FEATURES...

A DEEP LAYER TROUGH IS CENTERED ALONG 110W TO 115W BETWEEN 05N 
AND 20N WITH A 1008 MB SURFACE LOW FOUND AT 16N107W. THE 1216 
UTC AND 1356 UTC QUIKSCAT PASSES SHOW AN AREA OF S TO SW FLOW IN 
THE 20 TO 25 KT RANGE S OF THE ITCZ TOWARD THE LOW FROM 102W TO 
120W...FEEDING TROPICAL MOISTURE INTO THE CIRCULATION. AN AREA 
OF NUMEROUS MODERATE TO STRONG CONVECTION CAN BE FOUND WITHIN 
120 NM N QUADRANT OF THE LOW AND ELSEWHERE FROM 13N TO 18N 
BETWEEN 107W AND 112W. THIS SYSTEM IS UNDER A MODERATELY 
DIFFLUENT PATTERN BETWEEN THE UPPER LEVEL ANTICYCLONE CENTERED 
NEAR 20N110W AND THE NW EDGE OF THE BROAD UPPER TROUGH TO THE 
SE. DEEP CONVECTION IS EXPECTED TO BE SUSTAINED UNDER  
PERSISTENT UPPER LEVEL DIFFLUENCE AS THE SYSTEM TRACKS 
WESTWARD...MAKING THE ENVIRONMENTAL CONDITIONS FAVORABLE FOR 
THIS LOW TO POSSIBLY BECOME A TROPICAL CYCLONE OVER THE NEXT 48 
HOURS.

...TROPICAL WAVES...

A TROPICAL WAVE IS ANALYZED ALONG 103W N OF 06N TO THE MEXICAN 
COAST MOVING W AT 15 KT. SCATTERED MODERATE CONVECTION 
ASSOCIATED WITH THE WAVE CAN BE FOUND WITHIN 90 NM EITHER SIDE 
OF THE ITCZ AXIS E OF THE WAVE TO 99W.

A TROPICAL WAVE IS ANALYZED FROM 17N115W TO 06N117W MOVING W 10 
KT. SCATTERED MODERATE CONVECTION CAN BE FOUND WITHIN 180 NM E 
OF THE WAVE AXIS N FROM 14N TO 17N.

...THE ITCZ...

THE INTERTROPICAL CONVERGENCE ZONE IS ALONG THE LINE 07N77W TO 
05N85W TO 15N102W TO 11N120W TO 06N140W. SCATTERED MODERATE 
CONVECTION CAN BE FOUND WITHIN 90 NM EITHER SIDE OF THE ITCZ 
AXIS BETWEEN 99W AND 103W. SCATTERED MODERATE WITH ISOLATED 
STRONG CONVECTION CAN ALSO BE FOUND WITHIN 90 NM N AND 150 NM S 
OF THIS ITCZ AXIS BETWEEN 126W AND 136W.

...DISCUSSION...

N OF 20N....THE HIGHLY AMPLIFIED DEEP LAYER TROUGH CURRENTLY 
OVER THE WESTERN CONTINENTAL U.S. IS TURNING NEGATIVE TILT. THE 
SOUTHERN EDGE OF MID TO UPPER LEVEL TROUGH IS LIFTING NE TOWARD 
UTAH ALLOWING RIDGING TO BUILD OVER FORECAST WATERS TO ITS S AND 
DISSIPATING THE SURFACE COLD FRONT THAT CURRENTLY LIES FROM  
30N121W TO 27N130W. MUCH OF THE AREA E OF 130W IS CURRENTLY DRY 
AND CLOUD FREE IN THE MIDDLE AND UPPER LEVELS WITH OVERCAST 
STRATOCUMULUS FOUND MAINLY S OF THE FRONT BETWEEN 115W AND 125W. 
ON TUESDAY...A STRONG MIDDLE LATITUDE TROUGH WILL APPROACH NW 
FORECAST WATERS. THIS TROUGH WILL LIFT THE REMNANT LOW OF 
LINDA...CURRENTLY NEAR 20N136W...NORTHWESTWARD AND BRING SW 
SHEAR OVER THE SYSTEM THAT SHOULD DISSIPATE THE LOW LEVEL 
CIRCULATION TO A TROUGH. UNFORTUNATELY...THE SCATTEROMETER 
PASSES FROM THIS MORNING AND THIS AFTERNOON MISSED THE REMNANTS 
OF LINDA...BUT THE EARLIER 0250 UTC QUIKSCAT PASS SHOWED WINDS 
STILL OVER 20 KT IN THE NW QUADRANT OF THE REMNANT LOW.

S OF 20N...ASIDE FROM THE AFOREMENTIONED SPECIAL FEATURE...THE 
TWO TROPICAL WAVES...AND THE CONVECTION ALONG THE 
ITCZ...CONDITIONS ARE RELATIVELY QUIET OVER THE REMAINDER OF THE 
AREA. SCATTERED MODERATE CONVECTION CAN BE FOUND FROM 09N TO 12N 
BETWEEN 88W AND 90W. THIS CONVECTION LIES IN AN AREA OF UPPER 
LEVEL DIFFLUENCE ON THE EASTERN SIDE OF AN INVERTED TROUGH ALONG 
91W WITH A 40 KT UPPER LEVEL NORTHEASTERLY JET ON ITS WESTERN 
SIDE. THE UPPER JET EXTENDS ACROSS GUATEMALA SW TO 00N105W. THE 
SHEAR INDUCED BY THIS JET IS INHIBITING CONVECTION ALONG THE 
ITCZ BETWEEN 90W AND THE EASTERN TROPICAL WAVE.

$$
SCHAUER CLARK