Tropical Weather Discussion
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000
AXPZ20 KNHC 312145
TWDEP

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
2205 UTC FRI JUL 31 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
2130 UTC.

...SPECIAL FEATURES...

AT 2100 UTC JUL 31....HURRICANE GUILLERMO WAS CENTERED NEAR
12.7N 134.7W...OR ABOUT 1240 NM...2300 KM ESE OF HILO HAWAII
MOVING WNW OR 285 DEG AT 16 KT. THE ESTIMATED MINIMUM CENTRAL
PRESSURE WAS 970 MB WITH MAXIMUM SUSTAINED WINDS ARE NOW 90 KT
WITH GUSTS TO 110 KT...MAKING GUILLERMO A CATEGORY TWO HURRICANE
ON THE SAFFIR-SIMPSON SCALE.  GUILLERMO IS FORECAST TO INTENSIFY
TO A MAJOR HURRICANE LATER TONIGHT OR SAT...BEFORE BEGINNING A
SLOW WEAKENING TREND THROUGH THE REMAINDER OF THE WEEKEND.
CONVECTIVE ACTIVITY ASSOCIATED WITH THE STORM CONTINUES TO
ORGANIZE WITH AN EYE APPEARING INTERMITTENTLY OVER THE PAST FEW
HOURS. CURRENTLY...NUMEROUS STRONG CONVECTION WAS NOTED WITHIN
90 NM OF CENTER IN THE N SEMICIRCLE AND 75 NM IN THE S
SEMICIRCLE. AN AREA OF SCATTERED STRONG CONVECTION WAS WELL
REMOVED FROM THE CENTER...ABOUT 300 NM IN NE QUADRANT IN AN AREA
FROM 14N TO 17N BETWEEN 128W AND 133W. PLEASE READ THE LATEST
NHC FORECAST/ADVISORY UNDER AWIPS/WMO HEADER MIATCMEP4/WTPZ24
KNHC FOR ADDITIONAL DETAILS.

...TROPICAL WAVES...

A TROPICAL WAVE IS ALONG 100W FROM 17N SOUTHWARD...MOVING
WESTWARD 15 TO 20 KNOTS. SCATTERED MODERATE ISOLATED STRONG
CONVECTION IS FROM 10N TO 13N WITHIN 240 NM E OF WAVE AXIS.

A TROPICAL WAVE IS ALONG 112 FROM 05N TO 13N...MOVING WESTWARD
15 KNOTS. NO SIGNIFICANT CONVECTION IS DIRECTLY ASSOCIATED WITH
THE WAVE.

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

MONSOON TROUGH FROM 07N78W TO 09N100W TO 06N110W. SCATTERED
MODERATE TO STRONG WITHIN 240 NM N OF AXIS BETWEEN 102W AND
110W. SCATTERED MODERATE WITHIN 180-240 NM EITHER SIDE OF AXIS
BETWEEN 90W AND 102W.

...DISCUSSION...

A WEAK SURFACE RIDGE EXTENDS FROM A 1020 MB HIGH PRESSURE
CENTERED NEAR 28N125W TO 18N113W. THE GRADIENT BETWEEN THE RIDGE
AND LOWER PRESSURE ALONG THE MONSOON TROUGH IS FAIRLY WEAK WITH
ONLY MODERATE TRADES NOTED AND SEA HEIGHTS OF 6 TO 7 FEET. THE
GRADIENT BECOMES MORE PRONOUNCED W OF 128W BETWEEN THE RIDGE AND
THE WESTWARD MOVING HURRICANE GUILLERMO. A BROAD SWATH OF 20 TO
30 KT WINDS AND SEAS GREATER THAN 8 FT EXTEND WELL N OF THE
HURRICANE OVER THE EAST PACIFIC FROM 15N TO 20N BETWEEN 125W AND
138W.

A SURFACE HIGH IS EXPECTED TO REMAIN IN PLACE THROUGH SUN.
HOWEVER SOME INCREASE IN THE GRADIENT BETWEEN THE HIGH AND LOWER
SURFACE PRESSURES OVER MEXICO IS FORECAST TO DEVELOP WITHIN 120
NM OF THE COAST OF BAJA CALIFORNIA SAT NIGHT AND SUN WITH NW
WINDS OF 20 TO LOCALLY 25 KT FORECAST TO DEVELOP.

CROSS-EQUATORIAL SWELL WILL INCREASE SEAS TO 7-8 FT ACROSS THE
TROPICS S OF 06N BETWEEN 95-130W TODAY AND CONTINUE N REACHING
ALONG 10N BY SUN.

GAP WINDS...
WINDS IN THE THE GULF OF PAPAGAYO HAVE DROPPED TO AROUND 20 KT
WITH AN AREA OF RESIDUAL 8 FOOT SEAS NOTED FROM 09N TO 12N E OF
90W. THE WINDS AND SEAS ARE FORECAST TO FALL BELOW CRITERIA FOR
THE HIGH SEAS LATER THIS EVENING AND REMAIN SO THROUGH 48 HOURS.

$$
COBB



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