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Eastern Pacific Tropical Weather Discussion (Text)



000
AXPZ20 KNHC 040242
TWDEP 

TROPICAL WEATHER DISCUSSION                                     
NWS NATIONAL HURRICANE CENTER MIAMI FL                         
0405 UTC SAT JUL 04 2015

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 
0200 UTC. 

...SPECIAL FEATURES... 

BANDS OF CONVECTION AROUND A 1007 MB LOW PRES CENTERED NEAR 
06N120W HAVE BECOME BETTER ORGANIZED ALTHOUGH CLOUD TOPS HAVE 
WARMED SLIGHTLY IN THE PAST SEVERAL HOURS. THE LOW FORMED ALONG 
A WELL DEFINED TROPICAL WAVE IN A LARGE AREA OF CONVECTION THAT 
HAS BEEN FAIRLY PERSISTENT FOR THE PAST COUPLE OF DAYS ALONG THE 
ITCZ BETWEEN 115W AND 135W. AN UPPER ANTICYCLONE HAS FORMED NE 
OF THE LOW LEVEL CENTER IN THE CONTINUOUS OUTFLOW OF THESE 
THUNDERSTORMS. THE LOW LEVEL CENTER IS SOMEWHAT EXPOSED 
CURRENTLY WITH WEAK EASTERLY SHEAR...BUT CONVECTION IS EXPECTED 
TO PERSIST AND TROPICAL CYCLONE DEVELOPMENT IS POSSIBLE OVER THE 
NEXT COUPLE OF DAYS AS THE LOW MOVES SLOWLY W-NW. 

A 1007 MB LOW IS CENTERED NEAR 12N138W IS CURRENTLY STATIONARY 
BUT WILL DRIFT SLOWLY NW THROUGH SAT. AN 18 UTC ASCAT PASS 
INDICATED FRESH WINDS N THE E AND NW QUADRANTS OF THE LOW PRES. 
CONVECTION HAS WEAKENED CONSIDERABLY OVER THE PAST SEVERAL 
HOURS. ENVIRONMENTAL SHEAR AND CONDITIONS ARE MARGINAL FOR 
POSSIBLE TROPICAL CYCLONE DEVELOPMENT OVER THE NEXT COUPLE OF 
DAYS AS THE LOW CONTINUES TO DRIFT SLOWLY NW.

...TROPICAL WAVES...                                     
TROPICAL WAVE ALONG 93W/94W N OF 10N MOVING W AT 10 TO 15 KT. NO 
SIGNIFICANT CONVECTION NOTED DIRECTLY RELATED TO THE WAVE OVER 
THE WATER.

TROPICAL WAVE ALONG 109W/110W FROM 08N TO 14N MOVING W AT 10 TO 
15 KT. THE WAVE SHOWS UP WEAKLY IN REMOTE SENSED DATA BUT IS 
WELL INITIALIZED IN THE LOWER TO MID LEVELS OF THE ATMOSPHERE IN 
GLOBAL MODELS. SCATTERED MODERATE CONVECTION IS NOTED NEAR THE 
WAVE WITHIN 120 NM EITHER SIDE OF THE ITCZ AXIS 107W AND 
113W.

...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH...           
THE MONSOON TROUGH EXTENDS FROM 07N77W TO 06N80W TO 08N85W TO 
10N93W. THE ITCZ EXTENDS FROM 10N93W TO 09N110W TO 13N117W...AND 
FROM LOW PRES NEAR 06N120W 1007 MB TO 09N130W. SCATTERED 
MODERATE CONVECTION NOTED WITHIN 180 NM S OF MONSOON TROUGH E OF 
80W. SCATTERED MODERATE CONVECTION NOTED WITHIN 240 NM EITHER 
SIDE OF ITCZ BETWEEN 95W AND 115W. SCATTERED MODERATE ISOLATED 
STRONG CONVECTION NOTED FROM 06N TO 11N BETWEEN 115W AND 125W. 

...DISCUSSION...                                                
N OF 15N E OF 120W...A RELATIVELY TIGHT PRES GRADIENT IS IN 
PLACE BETWEEN 1005 MB LOW PRES IN THE LOWER COLORADO RIVER 
VALLEY AND WEAK 1017 MB HIGH PRES W OF THE AREA IS ENOUGH TO 
ALLOW FRESH TO STRONG NW WINDS ALONG THE COAST OF BAJA 
CALIFORNIA FROM CABO SAN LAZARO TO PUNTA EUGENIA. THIS IS 
EXPECTED TO DIMINISH LATE THIS EVENING AS THE GRADIENT 
WEAKENS...AND SEAS WILL REMAIN LESS THAN 8 FT. FARTHER SOUTH...A 
SMALL UPPER LOW CENTERED NEAR 12N97W IS SUPPORTING A FEW SHOWERS 
AND THUNDERSTORMS TO ITS SOUTH CLOSER TO THE ITCZ. RECENT 
SCATTEROMETER AND ALTIMETER PASSES INDICATE LIGHT TO MODERATE 
WINDS AND SEAS OF 3 TO 5 FT OVER OPEN WATERS ELSEWHERE N OF 15N 
E OF 120W.

S OF 15N E OF 110W...A 2230 UTC RAPIDSCAT PASS INDICATES 20 TO 
25 KT IN THE GULF OF PAPAGAYO...INDICATIVE OF STRONG TRADE WIND 
FLOW OVER THE SW CARIBBEAN THAT CONTINUES TO PRODUCE STRONG GAP 
WINDS INTO THE GULF OF PAPAGAYO AND OTHER AREAS ALONG THE 
NICARAGUAN COAST. THE MAIN PULSES ARE OCCURRING 
OVERNIGHT...WITH A PLUME OF FRESH SWELL TO 8 FT PROPAGATING AS 
FAR WEST AS 92W DOWNSTREAM DURING THE DAY. THESE CONDITIONS WILL 
START TO ABATE BY 48 HOURS. FRESH GAP WINDS WILL CONTINUE 
THROUGH THE GULF OF PANAMA AS WELL OVER THE NEXT 24 TO 48 HOURS. 
SCATTERED SHOWERS AND THUNDERSTORMS WILL CONTINUE ALONG THE ITCZ 
BETWEEN 90W AND 100W...ENHANCED BY GAP WIND CONVERGENCE TO SOME 
EXTENT. LITTLE CHANGE IS EXPECTED OVER THE NEXT 48 HOURS.

ELSEWHERE...A KELVIN WAVE MOVING THROUGH THE AREA HAS HELPED 
INCREASE LOW LEVEL CONVERGENCE MAKING MUCH OF THE ITCZ REGION 
ACTIVE BETWEEN 90W AND 125W AS NOTED IN THE ITCZ SECTION ABOVE. 
THIS IS RESULTING IN A BREAKDOWN OF THE ITCZ AS EVIDENCED BY THE 
DEVELOPING LOW PRES AREAS NEAR 06N120W AND 13N138W. THE ONLY 
OTHER MAIN WEATHER INFLUENCE AT THE SURFACE IS A WEAK 
SUBTROPICAL RIDGE N OF 20N...SUPPORTING WEAK MODEST TRADE WINDS 
OUTSIDE OF AREAS NEAR THE DEVELOPING LOW PRES AREAS. 

$$
CHRISTENSEN

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Page last modified: Saturday, 04-Jul-2015 02:42:52 UTC