Tropical Weather Discussion
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000
AXPZ20 KNHC 052154
TWDEP

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
2205 UTC TUE MAY 05 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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY
THROUGH 2145 UTC.

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

SCATTEROMETER WINDS INDICATE THAT THE MONSOON TROUGH FORMS NEAR
06N90W AND EXTEND S SW TO AN EMBEDDED 1010 MB LOW PRESSURE AT
05N98W...AND THEN CONTINUES W TO 05N107W WHERE SCATTEROMETER
WINDS INDICATE A TRANSITION TO AN ITCZ. THE ITCZ EXTENDS NW TO
AN EMBEDDED TROUGH AT 10N121W...THEN TURNS SW TO BEYOND
04.5N140W. THE ITCZ EMBEDDED TROUGH IS ANALYZED FROM 07N121W TO
13N120W. SCATTERED MODERATE ISOLATED STRONG CONVECTION IS NOTED
NEAR THE EASTERN PORTION OF THE MONSOON TROUGH...WITHIN 240 NM
OF 04N89W. SIMILAR CONVECTION IS OBSERVED S OF THE EMBEDDED LOW
PRESSURE...WITHIN 120 NM EITHER SIDE OF A LINE FROM 01N95W TO
05N108W. SCATTERED MODERATE ISOLATED STRONG CONVECTION IS
FLARING N OF THE ITCZ AND EXTENDS SW ALONG THE EMBEDDED TROUGH
WITHIN 90 NM EITHER SIDE OF A LINE FROM 11N111W TO 11N119W TO
07N125W. ISOLATED CELLS OF MODERATE CONVECTION ARE NOTED
ELSEWHERE FROM 02S-10N BETWEEN 84-137W.

A 1009 MB LOW PRESSURE CENTER IS ANALYZED ALONG THE CARIBBEAN
COAST OF COLOMBIA NEAR 11N75.5W WITH A TROUGH EXTENDING SW
ACROSS THE COLOMBIA/PANAMA BORDER TO A BASE OVER THE TROPICAL
PACIFIC NEAR 06N79W. SCATTERED MODERATE CONVECTION OCCASIONALLY
FLARES WITHIN 45 NM EITHER SIDE OF THIS TROUGH.

...DISCUSSION...

AN UPPER CYCLONE IS OBSERVED AT 35N124W WITH AN UPPER TROUGH
EXTENDING SSW TO BASE AT 23N127W. AN UPPER ANTICYCLONE IS
CENTERED NEAR 11N114W WITH AN UPPER RIDGE EXTENDING W ACROSS THE
TROPICAL PACIFIC TO BEYOND 08N140W. AN UPPER RIDGE ALSO EXTENDS
E FROM THE ANTICYCLONE TO A FAIRLY SHARP CREST OVER COASTAL
NORTHERN COSTA RICA. SOME UPPER MOISTURE IS ROTATING
CYCLONICALLY AROUND THE UPPER CYCLONE AND WILL PASS NE ACROSS
SOUTHERN CALIFORNIA TONIGHT. OTHERWISE VERY DRY UPPER AIR IS
INDICATED OVER THE NORTHERN PORTION OF THE DISCUSSION AREA
INCLUDING NORTHERN MEXICO...ROUGHLY N OF A LINE FROM 28N110W TO
21N140W. UPPER DIFFLUENCE ALONG THE PREVIOUSLY DESCRIBED WESTERN
TROPICAL RIDGE IS ENHANCING CONVECTION ALONG THE ITCZ AND ITS
EMBEDDED TROUGH ALSO PREVIOUSLY DESCRIBED. THE RESULTANT DEBRIS
MOISTURE IS ADVECTED N FROM THE ITCZ BETWEEN 110W AND 120W. THIS
MOISTURE MERGES AT 20N110W WITH A TROPICAL PLUME ORIGINATING IN
THE CENTRAL PACIFIC THAT STREAMS ENE ACROSS THE DISCUSSION AREA
WITHIN 150 NM EITHER SIDE OF A LINE FROM 17N140W TO ACROSS
SOUTHERN BAJA AND CENTRAL MEXICO. UPPER DIFFLUENCE ALONG THE
EASTERN TROPICAL RIDGE IS ENHANCING CONVECTION OVER AND TO THE S
OF THE MONSOON TROUGH AS PREVIOUSLY DESCRIBED...WITH THE UPPER
DEBRIS MOISTURE ADVECTED S ACROSS THE EQUATOR BETWEEN 85-118W.

ELSEWHERE AT THE LOW LEVELS A SURFACE RIDGE EXTENDS FROM 32N137W
TO 16N104W. A SURFACE TROUGH EMBEDDED IN THE ITCZ FROM 07N121W
TO 13N120W IS FORECAST TO SHIFT W FROM 05N131W TO 14N126W ON WED
AND FROM 04N134W TO 13N129W ON THU. THE GRADIENT IS EXPECTED TO
TIGHTEN SW OF THE RIDGE AXIS OVER THE NEXT FEW DAYS INCREASING
THE NE TRADES TO 20-25 KT BETWEEN THE TROUGH AND THE RIDGE WITH
SEAS BUILDING 7-10 FT IN THE NE WINDS WAVES THAT WILL MIX WITH
LONG PERIOD SW AND NW SWELL. ALTHOUGH THE TROUGH WILL MOVE W OF
140W ON FRI...EXPECT THE FRESH NE TRADES TO CONTINUE THROUGH THE
UPCOMING WEEKEND ACROSS THE TROPICAL WATERS BETWEEN 08-19W WITH
EMBEDDED PATCHES OF STRONG TRADES. FRESH NW-N WINDS ARE EXPECTED
ACROSS THE SUBTROPICAL WATERS NE OF THE RIDGE INTO THE UPCOMING
WEEKEND. LONG PERIOD NW SWELL WILL PROPAGATE S INTO THE
DISCUSSION AREA AND MIX WITH LONG PERIOD SOUTHERLY SWELL DRIVING
THE COMBINED SEAS TO 7-10 FT ACROSS THE WATERS N OF 28N BETWEEN
116-128W THROUGH THU NIGHT...THEN GRADUALLY SUBSIDING THEREAFTER.

ANOTHER BATCH OF LONG PERIOD SW SWELL WILL CROSS THE EQUATOR
BETWEEN 92-120W ON SUN NIGHT REACHING ALONG 03N ON MON.

GULF OF CALIFORNIA...A SURFACE LOW WILL MOVE E OVER THE FAR
NORTHERN GULF OF CALIFORNIA TONIGHT WHERE IT WILL MEANDER
THROUGH FRI. THE GRADIENT WILL SUPPORT S-SW 20-25 KT PULSES
WITHIN ABOUT 90 NM S OF THE CENTER. AS THE LOW MOVES E ON THU
NIGHT THE GRADIENT MAY BRIEFLY SUPPORT NW-N 20-25 KT WINDS OVER
THE NW QUADRANT AS WELL. THE BRIEF STRONG PULSES WITH LIMITED
FETCH SHOULD ONLY ALLOW SEAS TO BUILD TO 7 FT.

$$
NELSON


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