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Eastern North Pacific Tropical Weather Discussion (Text)



000
AXPZ20 KNHC 041605
TWDEP 

TROPICAL WEATHER DISCUSSION                                  
NWS NATIONAL HURRICANE CENTER MIAMI FL                      
1605 UTC WED MAY 04 2016

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
1545 UTC.

...SPECIAL FEATURES...

A LATE SEASON GULF OF TEHUANTEPEC GAP WIND EVENT WILL BE INDUCED
BY A DEVELOPING TIGHT PRES GRADIENT IN THE WAKE OF A COLD FRONT
CURRENTLY MOVING ACROSS THE SW GULF OF MEXICO. THE GRADIENT WILL
INDUCE N TO NE WINDS AT 20-30 KT BEGINNING LATE TONIGHT...AND
INTO THE DAYBREAK HOURS OF THU THROUGH THE ISTHMUS OF
TEHUANTEPEC...AND OUT OVER THE GULF WITHIN 30 NM EITHER SIDE OF
A LINE FROM 16N95W TO 15N95W WITH SEAS LESS THAN 8 FT INITIALLY.
THESE WINDS ARE FORECAST BY MOST NWP MODELS TO FURTHER INCREASE
TO MINIMAL GALE FORCE LATE THU NIGHT INTO FRI MORNING WITH SEAS
BUILDING TO AROUND 12 FT IN AND DOWNSTREAM OF THE GULF. WINDS
ARE EXPECTED TO DIMINISH TO BELOW GALE FORCE LATE FRI MORNING
WITH SEAS SUBSIDING TO 8-10 FT.

...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... 

THE PREVIOUS ANALYZED MONSOON TROUGH HAS WEAKENED TO A TROUGH
THAT EXTENDS FROM 12N87W TO LOW PRES NEAR 08N98W 1009 MB TO
07N105W WHERE BOTH SCATTEROMETER AND MODEL DATA SUGGEST THAT IT
TRANSITIONS TO THE ITCZ AXIS TO 07N105W TO 05N120W TO 05N130W TO
BEYOND 05N140W. NUMEROUS STRONG CONVECTION IS WITHIN 180 NM N
AND 60 NM S OF THE AXIS BETWEEN 115W-119W. SCATTERED MODERATE TO
STRONG CONVECTION IS WITHIN 60 NM OF THE AXIS BETWEEN 119W-130W.
SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS WITHIN 120 NM S
OF THE TROUGH BETWEEN 100W-104W...AND ALSO WITHIN 60 NM OF THE
AXIS BETWEEN 130W-135W.

...DISCUSSION...

THE ATMOSPHERIC MOISTURE CONTENT HAS INCREASED CONSIDERABLY
DURING THE PAST 2-3 DAYS ACROSS THE CENTRAL TROPICAL REGION OF
THE AREA ROUGHLY FROM 04N TO 11N AND BETWEEN 115W-130W AS NOTED
IN THE MOISTURE CONTENT AS DISPLAYED IN THE WATER VAPOR
SATELLITE CHANNEL. THIS IS LEADING TO INCREASING LARGE CLUSTERS
OF CONVECTION AS DESCRIBED ABOVE UNDER ITCZ/MONSOON TROUGH.

A WEAK 1015 MB LOW IS JUST N OF THE AREA AT 31N28W WITH A
DISSIPATING OCCLUDED FRONT TO 30N127W. IT THEN TRANSITIONS TO A
COLD FRONT TO 24N130W TO 21N140W. FRESH TO STRONG NLY WINDS
PREVAIL W OF THE FRONT WITH SEAS IN THE RANGE OF 8-10 FT...
EXCEPT FOR 10-12 FT SEAS ATTRIBUTED TO NW SWELL N OF 27N AND W
OF THE FRONT TO 135W. THE LOW PRES IS FORECAST TO REMAIN WEAK AS
MOVES SE TO NEAR 30N122W BY EARLY IN THU WITH THE ASSOCIATED
COLD FRONT DISSIPATING TO NEAR 25N125W AND TO NEAR 20N130W WHERE
IT IS TO BECOME DISSIPATING TO 20N140W. FRESH N WINDS ARE
FORECAST TO SHRINK IN COVERAGE AT THAT TIME TO N OF 26N BETWEEN
128W-135W WITH SEAS OF 9-10 FT. SEAS ELSEWHERE W OF THE FRONT
ARE EXPECTED TO BE 8-9 FT IN NW SWELL ALSO AT THAT TIME...EXCEPT
FOR SEAS OF LESS THAN 8 FT NW OF LINE FROM 32N136W TO 27N140W.
THE LOW IS FORECAST TO DISSIPATE BY EARLY ON FRI...WITH FRONTAL
REMNANTS FROM NEAR 32N116W TO 23N124W. AS NW SWELL ENERGY
DISSIPATES GOING INTO EARLY FRI...THE SEAS WILL RESPOND BY
LOWERING TO 8-9 FT N OF ABOUT 24N AND BETWEEN 122W-133W. 

A RIDGE DOMINATES THE REMAINDER OF THE FORECAST WATERS N OF 15N
W OF 110W. THE PRES GRADIENT BETWEEN THIS RIDGE AND LOWER
PRESSURE IN THE VICINITY OF THE ITCZ IS SUPPORTING MODERATE TO
LOCALLY FRESH TRADES MAINLY FROM 07N TO 15N W OF 120W. HIGH
PRESSURE BUILDING BEHIND THE FRONT WILL BRING SOME INCREASE IN
THE TRADE WIND FLOW OVER THE WEST-CENTRAL WATERS TODAY. MARINE
GUIDANCE SUGGESTS MODERATE TO FRESH TRADE WINDS AND SEAS OF 7-8
FT THROUGH FRI. 

THE WEAK LOW PRES OF 1009 MB ON THE MONSOON TROUGH NEAR 08N98W
IS MOVING WESTWARD. FIRST VISIBLE IMAGERY FROM THIS MORNING
SHOWS THAT THE ASSOCIATED CYCLONIC CIRCULATION IS BROAD AND
DISORGANIZED. CONVECTION DIRECTLY TIED TO THE LOW REMAINS
MINIMAL AS STRONGER CONVECTION IS TO ITS W IN ASSOCIATION WITH
THE MONSOON TROUGH. THE LOW IS FORECAST TO DISSIPATE IN 24
HOURS. 

GULF OF CALIFORNIA...A SURFACE TROUGH WILL DEVELOP OVER SOUTHERN
CALIFORNIA AND NORTHERN BAJA TONIGHT AND THU. A TIGHTENING PRES
GRADIENT BETWEEN THE TROUGH AND THE STRONG HIGH PRES RIDGING TO
ITS W ACROSS THE OCEANIC AREA WILL INCREASE S-SW WINDS AHEAD OF
THE TROUGH TO THE 20-TO 25 KT RANGE BEGINNING LATE TONIGHT.
THESE WINDS ARE FORECAST TO BRIEFLY DIMINISH TO 15-20 KT BY
EARLY THU AFTERNOON...THEN START UP AGAIN LATE ON THU NIGHT IN
RESPONSE TO ANOTHER TIGHTENING OF THE PRES GRADIENT AS THE HIGH
PRES NUDGES EASTWARD TOWARDS BAJA CALIFORNIA. MODEL GUIDANCE 
SUGGEST THAT S-SW WINDS INCREASE TO 20-30 KT ALSO LATE ON 
THU NIGHT...AND DIMINISH BACK TO 20-25 KT TOWARD DAYBREAK ON FRI.
MAX SEAS ARE EXPECTED TO REACH AROUND 6 FT THU NIGHT BEFORE 
SUBSIDING TO 5 FT FRI. 

$$ 
AGUIRRE

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Page last modified: Wednesday, 04-May-2016 16:05:51 UTC